diff --git a/CHANGELOG.md b/CHANGELOG.md
index a44aedcefe0..7d997e70255 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,19 @@ full changeset diff at the end of each section.
 Current Trunk
 -------------
 
+ - StackIR is now handled entirely during binary writing. This is mostly not
+   noticeable, except that:
+   - Text output no longer notes `(; has Stack IR ;)` (as Stack IR only exists
+     during binary writing).
+   - `--generate-stack-ir`, `--optimize-stack-ir`, and `--print-stack-ir` are
+     now flags and not passes. That means the order of operations may seem
+     different, as they apply during binary writing (or, if no binary is written
+     but we were still asked to print StackIR, `wasm-opt` does it at the very
+     end).
+   - Whether to generate, optimize, and print StackIR is now noted as part of
+     the PassOptions. As a result `BinaryenModulePrintStackIR` and similar APIs
+     do not receive an `optimize` flag, as they read the PassOption
+     `optimizeStackIR` instead.
  - The new, standards-compliant text parser is now the default. `wasm-opt` has a
    `--deprecated-wat-parser` flag that will switch back to using the old text
    parser, but that option will go away soon.
diff --git a/src/binaryen-c.cpp b/src/binaryen-c.cpp
index f27f6e2c89c..1c9a5be0e76 100644
--- a/src/binaryen-c.cpp
+++ b/src/binaryen-c.cpp
@@ -5590,8 +5590,8 @@ void BinaryenModulePrint(BinaryenModuleRef module) {
   std::cout << *(Module*)module;
 }
 
-void BinaryenModulePrintStackIR(BinaryenModuleRef module, bool optimize) {
-  wasm::printStackIR(std::cout, (Module*)module, optimize);
+void BinaryenModulePrintStackIR(BinaryenModuleRef module) {
+  wasm::printStackIR(std::cout, (Module*)module, globalPassOptions);
 }
 
 void BinaryenModulePrintAsmjs(BinaryenModuleRef module) {
@@ -5737,7 +5737,7 @@ static BinaryenBufferSizes writeModule(BinaryenModuleRef module,
                                        char* sourceMap,
                                        size_t sourceMapSize) {
   BufferWithRandomAccess buffer;
-  WasmBinaryWriter writer((Module*)module, buffer);
+  WasmBinaryWriter writer((Module*)module, buffer, globalPassOptions);
   writer.setNamesSection(globalPassOptions.debugInfo);
   std::ostringstream os;
   if (sourceMapUrl) {
@@ -5778,12 +5778,11 @@ size_t BinaryenModuleWriteText(BinaryenModuleRef module,
 
 size_t BinaryenModuleWriteStackIR(BinaryenModuleRef module,
                                   char* output,
-                                  size_t outputSize,
-                                  bool optimize) {
+                                  size_t outputSize) {
   // use a stringstream as an std::ostream. Extract the std::string
   // representation, and then store in the output.
   std::stringstream ss;
-  wasm::printStackIR(ss, (Module*)module, optimize);
+  wasm::printStackIR(ss, (Module*)module, globalPassOptions);
 
   const auto temp = ss.str();
   const auto ctemp = temp.c_str();
@@ -5808,7 +5807,7 @@ BinaryenModuleAllocateAndWriteResult
 BinaryenModuleAllocateAndWrite(BinaryenModuleRef module,
                                const char* sourceMapUrl) {
   BufferWithRandomAccess buffer;
-  WasmBinaryWriter writer((Module*)module, buffer);
+  WasmBinaryWriter writer((Module*)module, buffer, globalPassOptions);
   writer.setNamesSection(globalPassOptions.debugInfo);
   std::ostringstream os;
   if (sourceMapUrl) {
@@ -5842,13 +5841,12 @@ char* BinaryenModuleAllocateAndWriteText(BinaryenModuleRef module) {
   return output;
 }
 
-char* BinaryenModuleAllocateAndWriteStackIR(BinaryenModuleRef module,
-                                            bool optimize) {
+char* BinaryenModuleAllocateAndWriteStackIR(BinaryenModuleRef module) {
   std::ostringstream os;
   bool colors = Colors::isEnabled();
 
   Colors::setEnabled(false); // do not use colors for writing
-  wasm::printStackIR(os, (Module*)module, optimize);
+  wasm::printStackIR(os, (Module*)module, globalPassOptions);
   Colors::setEnabled(colors); // restore colors state
 
   auto str = os.str();
diff --git a/src/binaryen-c.h b/src/binaryen-c.h
index bc63e963ae1..595086d6a25 100644
--- a/src/binaryen-c.h
+++ b/src/binaryen-c.h
@@ -2984,8 +2984,7 @@ BINARYEN_API BinaryenModuleRef BinaryenModuleParse(const char* text);
 BINARYEN_API void BinaryenModulePrint(BinaryenModuleRef module);
 
 // Print a module to stdout in stack IR text format. Useful for debugging.
-BINARYEN_API void BinaryenModulePrintStackIR(BinaryenModuleRef module,
-                                             bool optimize);
+BINARYEN_API void BinaryenModulePrintStackIR(BinaryenModuleRef module);
 
 // Print a module to stdout in asm.js syntax.
 BINARYEN_API void BinaryenModulePrintAsmjs(BinaryenModuleRef module);
@@ -3126,8 +3125,7 @@ BINARYEN_API size_t BinaryenModuleWriteText(BinaryenModuleRef module,
 //         outputSize
 BINARYEN_API size_t BinaryenModuleWriteStackIR(BinaryenModuleRef module,
                                                char* output,
-                                               size_t outputSize,
-                                               bool optimize);
+                                               size_t outputSize);
 
 typedef struct BinaryenBufferSizes {
   size_t outputBytes;
@@ -3173,7 +3171,7 @@ BINARYEN_API char* BinaryenModuleAllocateAndWriteText(BinaryenModuleRef module);
 // char* with malloc(), and expects the user to free() them manually
 // once not needed anymore.
 BINARYEN_API char*
-BinaryenModuleAllocateAndWriteStackIR(BinaryenModuleRef module, bool optimize);
+BinaryenModuleAllocateAndWriteStackIR(BinaryenModuleRef module);
 
 // Deserialize a module from binary form, assuming the MVP feature set.
 BINARYEN_API BinaryenModuleRef BinaryenModuleRead(char* input,
diff --git a/src/ir/module-utils.cpp b/src/ir/module-utils.cpp
index 8d9e88d182b..e169f0ff1ea 100644
--- a/src/ir/module-utils.cpp
+++ b/src/ir/module-utils.cpp
@@ -69,9 +69,6 @@ Function* copyFunction(Function* func,
   ret->base = func->base;
   ret->noFullInline = func->noFullInline;
   ret->noPartialInline = func->noPartialInline;
-
-  // TODO: copy Stack IR
-  assert(!func->stackIR);
   return out.addFunction(std::move(ret));
 }
 
diff --git a/src/js/binaryen.js-post.js b/src/js/binaryen.js-post.js
index 1461420bb61..dfde2d7effe 100644
--- a/src/js/binaryen.js-post.js
+++ b/src/js/binaryen.js-post.js
@@ -2688,8 +2688,8 @@ function wrapModule(module, self = {}) {
     if (textPtr) _free(textPtr);
     return text;
   };
-  self['emitStackIR'] = function(optimize) {
-    let textPtr = Module['_BinaryenModuleAllocateAndWriteStackIR'](module, optimize);
+  self['emitStackIR'] = function() {
+    let textPtr = Module['_BinaryenModuleAllocateAndWriteStackIR'](module);
     let text = UTF8ToString(textPtr);
     if (textPtr) _free(textPtr);
     return text;
diff --git a/src/pass.h b/src/pass.h
index 2c2fa06190c..ab060309b4b 100644
--- a/src/pass.h
+++ b/src/pass.h
@@ -219,6 +219,16 @@ struct PassOptions {
   bool closedWorld = false;
   // Whether to try to preserve debug info through, which are special calls.
   bool debugInfo = false;
+  // Whether to generate StackIR during binary writing. This is on by default
+  // in -O2 and above.
+  bool generateStackIR = false;
+  // Whether to optimize StackIR during binary writing. How we optimize depends
+  // on other optimization flags like optimizeLevel. This is on by default in
+  // -O2 and above.
+  bool optimizeStackIR = false;
+  // Whether to print StackIR during binary writing, and if so to what stream.
+  // This is mainly useful for debugging.
+  std::optional<std::ostream*> printStackIR;
   // Whether we are targeting JS. In that case we want to avoid emitting things
   // in the optimizer that do not translate well to JS, or that could cause us
   // to need extra lowering work or even a loop (where we optimize to something
diff --git a/src/passes/CMakeLists.txt b/src/passes/CMakeLists.txt
index 1e5540ab047..72fa02b62e4 100644
--- a/src/passes/CMakeLists.txt
+++ b/src/passes/CMakeLists.txt
@@ -87,7 +87,6 @@ set(passes_SOURCES
   PrintFunctionMap.cpp
   RoundTrip.cpp
   SetGlobals.cpp
-  StackIR.cpp
   SignaturePruning.cpp
   SignatureRefining.cpp
   SignExtLowering.cpp
diff --git a/src/passes/Metrics.cpp b/src/passes/Metrics.cpp
index d2e072a6f99..1778eb9bd09 100644
--- a/src/passes/Metrics.cpp
+++ b/src/passes/Metrics.cpp
@@ -94,7 +94,7 @@ struct Metrics
       printCounts("global");
       // compute binary info, so we know function sizes
       BufferWithRandomAccess buffer;
-      WasmBinaryWriter writer(module, buffer);
+      WasmBinaryWriter writer(module, buffer, getPassOptions());
       writer.write();
       // print for each function
       Index binaryIndex = 0;
@@ -108,14 +108,14 @@ struct Metrics
       });
       // print for each export how much code size is due to it, i.e.,
       // how much the module could shrink without it.
-      auto sizeAfterGlobalCleanup = [](Module* module) {
+      auto sizeAfterGlobalCleanup = [&](Module* module) {
         PassRunner runner(module,
                           PassOptions::getWithDefaultOptimizationOptions());
         runner.setIsNested(true);
         runner.addDefaultGlobalOptimizationPostPasses(); // remove stuff
         runner.run();
         BufferWithRandomAccess buffer;
-        WasmBinaryWriter writer(module, buffer);
+        WasmBinaryWriter writer(module, buffer, getPassOptions());
         writer.write();
         return buffer.size();
       };
diff --git a/src/passes/Monomorphize.cpp b/src/passes/Monomorphize.cpp
index f8ee4a6e63a..012f247504b 100644
--- a/src/passes/Monomorphize.cpp
+++ b/src/passes/Monomorphize.cpp
@@ -151,11 +151,6 @@ struct Monomorphize : public Pass {
     // monomorphizing.
 
     // Create a new function with refined parameters as a copy of the original.
-    // (Note we must clear stack IR on the original: atm we do not have the
-    // ability to copy stack IR, so we'd hit an internal error. But as we will
-    // be optimizing the function anyhow, we'd be throwing away stack IR later
-    // so this isn't a problem.)
-    func->stackIR.reset();
     auto refinedTarget = Names::getValidFunctionName(*module, target);
     auto* refinedFunc = ModuleUtils::copyFunction(func, *module, refinedTarget);
     TypeUpdating::updateParamTypes(refinedFunc, refinedTypes, *module);
diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 1ecf382d94c..99c86cec472 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -109,11 +109,11 @@ struct PrintSExpression : public UnifiedExpressionVisitor<PrintSExpression> {
   const char* maybeSpace;
   const char* maybeNewLine;
 
-  bool full = false;    // whether to not elide nodes in output when possible
-                        // (like implicit blocks) and to emit types
-  bool stackIR = false; // whether to print stack IR if it is present
-                        // (if false, and Stack IR is there, we just
-                        // note it exists)
+  // Whether to not elide nodes in output when possible (like implicit blocks)
+  // and to emit types.
+  bool full = false;
+  // If present, it contains StackIR that we will print.
+  std::optional<ModuleStackIR> moduleStackIR;
 
   Module* currModule = nullptr;
   Function* currFunction = nullptr;
@@ -268,7 +268,9 @@ struct PrintSExpression : public UnifiedExpressionVisitor<PrintSExpression> {
 
   void setFull(bool full_) { full = full_; }
 
-  void setStackIR(bool stackIR_) { stackIR = stackIR_; }
+  void generateStackIR(const PassOptions& options) {
+    moduleStackIR.emplace(*currModule, options);
+  }
 
   void setDebugInfo(bool debugInfo_) { debugInfo = debugInfo_; }
 
@@ -2978,9 +2980,6 @@ void PrintSExpression::visitDefinedFunction(Function* curr) {
     o << " (type ";
     printHeapType(curr->type) << ')';
   }
-  if (!stackIR && curr->stackIR && !minify) {
-    o << " (; has Stack IR ;)";
-  }
   if (curr->getParams().size() > 0) {
     Index i = 0;
     for (const auto& param : curr->getParams()) {
@@ -3007,7 +3006,13 @@ void PrintSExpression::visitDefinedFunction(Function* curr) {
     o << maybeNewLine;
   }
   // Print the body.
-  if (!stackIR || !curr->stackIR) {
+  StackIR* stackIR = nullptr;
+  if (moduleStackIR) {
+    stackIR = moduleStackIR->getStackIROrNull(curr);
+  }
+  if (stackIR) {
+    printStackIR(stackIR, *this);
+  } else {
     // It is ok to emit a block here, as a function can directly contain a
     // list, even if our ast avoids that for simplicity. We can just do that
     // optimization here..
@@ -3021,9 +3026,6 @@ void PrintSExpression::visitDefinedFunction(Function* curr) {
       printFullLine(curr->body);
     }
     assert(controlFlowDepth == 0);
-  } else {
-    // Print the stack IR.
-    printStackIR(curr->stackIR.get(), *this);
   }
   if (currFunction->epilogLocation.size()) {
     // Print last debug location: mix of decIndent and printDebugLocation
@@ -3430,14 +3432,12 @@ class PrintStackIR : public Printer {
   void run(Module* module) override {
     PrintSExpression print(o);
     print.setDebugInfo(getPassOptions().debugInfo);
-    print.setStackIR(true);
     print.currModule = module;
+    print.generateStackIR(getPassOptions());
     print.visitModule(module);
   }
 };
 
-Pass* createPrintStackIRPass() { return new PrintStackIR(); }
-
 static std::ostream& printExpression(Expression* expression,
                                      std::ostream& o,
                                      bool minify,
@@ -3602,12 +3602,9 @@ static std::ostream& printStackIR(StackIR* ir, PrintSExpression& printer) {
   return o;
 }
 
-std::ostream& printStackIR(std::ostream& o, Module* module, bool optimize) {
-  wasm::PassRunner runner(module);
-  runner.add("generate-stack-ir");
-  if (optimize) {
-    runner.add("optimize-stack-ir");
-  }
+std::ostream&
+printStackIR(std::ostream& o, Module* module, const PassOptions& options) {
+  wasm::PassRunner runner(module, options);
   runner.add(std::make_unique<PrintStackIR>(&o));
   runner.run();
   return o;
@@ -3659,9 +3656,4 @@ std::ostream& operator<<(std::ostream& o, wasm::StackInst& inst) {
   return wasm::printStackInst(&inst, o);
 }
 
-std::ostream& operator<<(std::ostream& o, wasm::StackIR& ir) {
-  wasm::PrintSExpression printer(o);
-  return wasm::printStackIR(&ir, printer);
-}
-
 } // namespace std
diff --git a/src/passes/RoundTrip.cpp b/src/passes/RoundTrip.cpp
index b930b195cf9..129b89ac818 100644
--- a/src/passes/RoundTrip.cpp
+++ b/src/passes/RoundTrip.cpp
@@ -41,7 +41,7 @@ struct RoundTrip : public Pass {
     // to tell the builder which features to build with.
     auto features = module->features;
     // Write, clear, and read the module
-    WasmBinaryWriter(module, buffer).write();
+    WasmBinaryWriter(module, buffer, getPassOptions()).write();
     ModuleUtils::clearModule(*module);
     auto input = buffer.getAsChars();
     WasmBinaryReader parser(*module, features, input);
diff --git a/src/passes/StackIR.cpp b/src/passes/StackIR.cpp
deleted file mode 100644
index 24b4fcbe844..00000000000
--- a/src/passes/StackIR.cpp
+++ /dev/null
@@ -1,505 +0,0 @@
-/*
- * Copyright 2018 WebAssembly Community Group participants
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-//
-// Operations on Stack IR.
-//
-
-#include "ir/iteration.h"
-#include "ir/local-graph.h"
-#include "pass.h"
-#include "wasm-stack.h"
-#include "wasm.h"
-
-namespace wasm {
-
-// Generate Stack IR from Binaryen IR
-
-struct GenerateStackIR : public WalkerPass<PostWalker<GenerateStackIR>> {
-  bool isFunctionParallel() override { return true; }
-
-  std::unique_ptr<Pass> create() override {
-    return std::make_unique<GenerateStackIR>();
-  }
-
-  bool modifiesBinaryenIR() override { return false; }
-
-  void doWalkFunction(Function* func) {
-    StackIRGenerator stackIRGen(*getModule(), func);
-    stackIRGen.write();
-    func->stackIR = std::make_unique<StackIR>();
-    func->stackIR->swap(stackIRGen.getStackIR());
-  }
-};
-
-Pass* createGenerateStackIRPass() { return new GenerateStackIR(); }
-
-// Optimize
-
-class StackIROptimizer {
-  Function* func;
-  PassOptions& passOptions;
-  StackIR& insts;
-  FeatureSet features;
-
-public:
-  StackIROptimizer(Function* func,
-                   PassOptions& passOptions,
-                   FeatureSet features)
-    : func(func), passOptions(passOptions), insts(*func->stackIR.get()),
-      features(features) {
-    assert(func->stackIR);
-  }
-
-  void run() {
-    dce();
-    // FIXME: local2Stack is currently rather slow (due to localGraph),
-    //        so for now run it only when really optimizing
-    if (passOptions.optimizeLevel >= 3 || passOptions.shrinkLevel >= 1) {
-      local2Stack();
-    }
-    removeUnneededBlocks();
-    dce();
-    vacuum();
-  }
-
-private:
-  // Passes.
-
-  // Remove unreachable code.
-  void dce() {
-    bool inUnreachableCode = false;
-    for (Index i = 0; i < insts.size(); i++) {
-      auto* inst = insts[i];
-      if (!inst) {
-        continue;
-      }
-      if (inUnreachableCode) {
-        // Does the unreachable code end here?
-        if (isControlFlowBarrier(inst)) {
-          inUnreachableCode = false;
-        } else {
-          // We can remove this.
-          removeAt(i);
-        }
-      } else if (inst->type == Type::unreachable) {
-        inUnreachableCode = true;
-      }
-    }
-  }
-
-  // Remove obviously-unneeded code.
-  void vacuum() {
-    // In the wasm binary format a nop is never needed. (In Binaryen IR, in
-    // comparison, it is necessary e.g. in a function body or an if arm.)
-    //
-    // It is especially important to remove nops because we add nops when we
-    // read wasm into Binaryen IR. That is, this avoids a potential increase in
-    // code size.
-    for (Index i = 0; i < insts.size(); i++) {
-      auto*& inst = insts[i];
-      if (inst && inst->origin->is<Nop>()) {
-        inst = nullptr;
-      }
-    }
-  }
-
-  // If ordered properly, we can avoid a local.set/local.get pair,
-  // and use the value directly from the stack, for example
-  //    [..produce a value on the stack..]
-  //    local.set $x
-  //    [..much code..]
-  //    local.get $x
-  //    call $foo ;; use the value, foo(value)
-  // As long as the code in between does not modify $x, and has
-  // no control flow branching out, we can remove both the set
-  // and the get.
-  void local2Stack() {
-    // We use the localGraph to tell us if a get-set pair is indeed
-    // a set that is read by that get, and only that get. Note that we run
-    // this on the Binaryen IR, so we are assuming that no previous opt
-    // has changed the interaction of local operations.
-    // TODO: we can do this a lot faster, as we just care about linear
-    //       control flow.
-    LocalGraph localGraph(func);
-    localGraph.computeSetInfluences();
-    // We maintain a stack of relevant values. This contains:
-    //  * a null for each actual value that the value stack would have
-    //  * an index of each LocalSet that *could* be on the value
-    //    stack at that location.
-    const Index null = -1;
-    std::vector<Index> values;
-    // We also maintain a stack of values vectors for control flow,
-    // saving the stack as we enter and restoring it when we exit.
-    std::vector<std::vector<Index>> savedValues;
-#ifdef STACK_OPT_DEBUG
-    std::cout << "func: " << func->name << '\n' << insts << '\n';
-#endif
-    for (Index instIndex = 0; instIndex < insts.size(); instIndex++) {
-      auto* inst = insts[instIndex];
-      if (!inst) {
-        continue;
-      }
-      // First, consume values from the stack as required.
-      auto consumed = getNumConsumedValues(inst);
-#ifdef STACK_OPT_DEBUG
-      std::cout << "  " << instIndex << " : " << *inst << ", " << values.size()
-                << " on stack, will consume " << consumed << "\n    ";
-      for (auto s : values)
-        std::cout << s << ' ';
-      std::cout << '\n';
-#endif
-      // TODO: currently we run dce before this, but if we didn't, we'd need
-      //       to handle unreachable code here - it's ok to pop multiple values
-      //       there even if the stack is at size 0.
-      while (consumed > 0) {
-        assert(values.size() > 0);
-        // Whenever we hit a possible stack value, kill it - it would
-        // be consumed here, so we can never optimize to it.
-        while (values.back() != null) {
-          values.pop_back();
-          assert(values.size() > 0);
-        }
-        // Finally, consume the actual value that is consumed here.
-        values.pop_back();
-        consumed--;
-      }
-      // After consuming, we can see what to do with this. First, handle
-      // control flow.
-      if (isControlFlowBegin(inst)) {
-        // Save the stack for when we end this control flow.
-        savedValues.push_back(values); // TODO: optimize copies
-        values.clear();
-      } else if (isControlFlowEnd(inst)) {
-        assert(!savedValues.empty());
-        values = savedValues.back();
-        savedValues.pop_back();
-      } else if (isControlFlow(inst)) {
-        // Otherwise, in the middle of control flow, just clear it
-        values.clear();
-      }
-      // This is something we should handle, look into it.
-      if (inst->type.isConcrete()) {
-        bool optimized = false;
-        // Do not optimize multivalue locals, since those will be better
-        // optimized when they are visited in the binary writer and this
-        // optimization would intefere with that one.
-        if (auto* get = inst->origin->dynCast<LocalGet>();
-            get && inst->type.isSingle()) {
-          // Use another local to clarify what instIndex means in this scope.
-          auto getIndex = instIndex;
-
-          // This is a potential optimization opportunity! See if we
-          // can reach the set.
-          if (values.size() > 0) {
-            Index j = values.size() - 1;
-            while (1) {
-              // If there's an actual value in the way, we've failed.
-              auto setIndex = values[j];
-              if (setIndex == null) {
-                break;
-              }
-              auto* set = insts[setIndex]->origin->cast<LocalSet>();
-              if (set->index == get->index) {
-                // This might be a proper set-get pair, where the set is
-                // used by this get and nothing else, check that.
-                auto& sets = localGraph.getSetses[get];
-                if (sets.size() == 1 && *sets.begin() == set) {
-                  auto& setInfluences = localGraph.setInfluences[set];
-                  // If this has the proper value of 1, also do the potentially-
-                  // expensive check of whether we can remove this pair at all.
-                  if (setInfluences.size() == 1 &&
-                      canRemoveSetGetPair(setIndex, getIndex)) {
-                    assert(*setInfluences.begin() == get);
-                    // Do it! The set and the get can go away, the proper
-                    // value is on the stack.
-#ifdef STACK_OPT_DEBUG
-                    std::cout << "  stackify the get\n";
-#endif
-                    insts[setIndex] = nullptr;
-                    insts[getIndex] = nullptr;
-                    // Continuing on from here, replace this on the stack
-                    // with a null, representing a regular value. We
-                    // keep possible values above us active - they may
-                    // be optimized later, as they would be pushed after
-                    // us, and used before us, so there is no conflict.
-                    values[j] = null;
-                    optimized = true;
-                    break;
-                  }
-                }
-              }
-              // We failed here. Can we look some more?
-              if (j == 0) {
-                break;
-              }
-              j--;
-            }
-          }
-        }
-        if (!optimized) {
-          // This is an actual regular value on the value stack.
-          values.push_back(null);
-        }
-      } else if (inst->origin->is<LocalSet>() && inst->type == Type::none) {
-        // This set is potentially optimizable later, add to stack.
-        values.push_back(instIndex);
-      }
-    }
-  }
-
-  // There may be unnecessary blocks we can remove: blocks
-  // without branches to them are always ok to remove.
-  // TODO: a branch to a block in an if body can become
-  //       a branch to that if body
-  void removeUnneededBlocks() {
-    for (auto*& inst : insts) {
-      if (!inst) {
-        continue;
-      }
-      if (auto* block = inst->origin->dynCast<Block>()) {
-        if (!BranchUtils::BranchSeeker::has(block, block->name)) {
-          // TODO optimize, maybe run remove-unused-names
-          inst = nullptr;
-        }
-      }
-    }
-  }
-
-  // Utilities.
-
-  // A control flow "barrier" - a point where stack machine
-  // unreachability ends.
-  bool isControlFlowBarrier(StackInst* inst) {
-    switch (inst->op) {
-      case StackInst::BlockEnd:
-      case StackInst::IfElse:
-      case StackInst::IfEnd:
-      case StackInst::LoopEnd:
-      case StackInst::Catch:
-      case StackInst::CatchAll:
-      case StackInst::Delegate:
-      case StackInst::TryEnd:
-      case StackInst::TryTableEnd: {
-        return true;
-      }
-      default: { return false; }
-    }
-  }
-
-  // A control flow beginning.
-  bool isControlFlowBegin(StackInst* inst) {
-    switch (inst->op) {
-      case StackInst::BlockBegin:
-      case StackInst::IfBegin:
-      case StackInst::LoopBegin:
-      case StackInst::TryBegin:
-      case StackInst::TryTableBegin: {
-        return true;
-      }
-      default: { return false; }
-    }
-  }
-
-  // A control flow ending.
-  bool isControlFlowEnd(StackInst* inst) {
-    switch (inst->op) {
-      case StackInst::BlockEnd:
-      case StackInst::IfEnd:
-      case StackInst::LoopEnd:
-      case StackInst::TryEnd:
-      case StackInst::Delegate:
-      case StackInst::TryTableEnd: {
-        return true;
-      }
-      default: { return false; }
-    }
-  }
-
-  bool isControlFlow(StackInst* inst) { return inst->op != StackInst::Basic; }
-
-  // Remove the instruction at index i. If the instruction
-  // is control flow, and so has been expanded to multiple
-  // instructions, remove them as well.
-  void removeAt(Index i) {
-    auto* inst = insts[i];
-    insts[i] = nullptr;
-    if (inst->op == StackInst::Basic) {
-      return; // that was it
-    }
-    auto* origin = inst->origin;
-    while (1) {
-      i++;
-      assert(i < insts.size());
-      inst = insts[i];
-      insts[i] = nullptr;
-      if (inst && inst->origin == origin && isControlFlowEnd(inst)) {
-        return; // that's it, we removed it all
-      }
-    }
-  }
-
-  Index getNumConsumedValues(StackInst* inst) {
-    if (isControlFlow(inst)) {
-      // If consumes 1; that's it.
-      if (inst->op == StackInst::IfBegin) {
-        return 1;
-      }
-      return 0;
-    }
-    // Otherwise, for basic instructions, just count the expression children.
-    return ChildIterator(inst->origin).children.size();
-  }
-
-  // Given a pair of a local.set and local.get, see if we can remove them
-  // without breaking validation. Specifically, we must keep sets of non-
-  // nullable locals that dominate a get until the end of the block, such as
-  // here:
-  //
-  //  local.set 0    ;; Can we remove
-  //  local.get 0    ;; this pair?
-  //  if
-  //    local.set 0
-  //  else
-  //    local.set 0
-  //  end
-  //  local.get 0    ;; This get poses a problem.
-  //
-  // Logically the 2nd&3rd sets ensure a value is applied to the local before we
-  // read it, but the validation rules only track each set until the end of its
-  // scope, so the 1st set (before the if, in the pair) is necessary.
-  //
-  // The logic below is related to LocalStructuralDominance, but sharing code
-  // with it is difficult as this uses StackIR and not BinaryenIR, and it checks
-  // a particular set/get pair.
-  //
-  // We are given the indexes of the set and get instructions in |insts|.
-  bool canRemoveSetGetPair(Index setIndex, Index getIndex) {
-    // The set must be before the get.
-    assert(setIndex < getIndex);
-
-    auto* set = insts[setIndex]->origin->cast<LocalSet>();
-    auto localType = func->getLocalType(set->index);
-    // Note we do not need to handle tuples here, as the parent ignores them
-    // anyhow (hence we can check non-nullability instead of non-
-    // defaultability).
-    assert(localType.isSingle());
-    if (func->isParam(set->index) || !localType.isNonNullable()) {
-      // This local cannot pose a problem for validation (params are always
-      // initialized, and it is ok if nullable locals are uninitialized).
-      return true;
-    }
-
-    // Track the depth (in block/if/loop/etc. scopes) relative to our starting
-    // point. Anything less deep than that is not interesting, as we can only
-    // help things at our depth or deeper to validate.
-    Index currDepth = 0;
-
-    // Look for a different get than the one in getIndex (since that one is
-    // being removed) which would stop validating without the set. While doing
-    // so, note other sets that ensure validation even if our set is removed. We
-    // track those in this stack of booleans, one for each scope, which is true
-    // if another sets covers us and ours is not needed.
-    //
-    // We begin in the current scope and with no other set covering us.
-    std::vector<bool> coverStack = {false};
-
-    // Track the total number of covers as well, for quick checking below.
-    Index covers = 0;
-
-    // TODO: We could look before us as well, but then we might end up scanning
-    //       much of the function every time.
-    for (Index i = setIndex + 1; i < insts.size(); i++) {
-      auto* inst = insts[i];
-      if (!inst) {
-        continue;
-      }
-      if (isControlFlowBegin(inst)) {
-        // A new scope begins.
-        currDepth++;
-        coverStack.push_back(false);
-      } else if (isControlFlowEnd(inst)) {
-        if (currDepth == 0) {
-          // Less deep than the start, so we found no problem.
-          return true;
-        }
-        currDepth--;
-
-        if (coverStack.back()) {
-          // A cover existed in the scope which ended.
-          covers--;
-        }
-        coverStack.pop_back();
-      } else if (isControlFlowBarrier(inst)) {
-        // A barrier, like the else in an if-else, not only ends a scope but
-        // opens a new one.
-        if (currDepth == 0) {
-          // Another scope with the same depth begins, but ours ended, so stop.
-          return true;
-        }
-
-        if (coverStack.back()) {
-          // A cover existed in the scope which ended.
-          covers--;
-        }
-        coverStack.back() = false;
-      } else if (auto* otherSet = inst->origin->dynCast<LocalSet>()) {
-        // We are covered in this scope henceforth.
-        if (otherSet->index == set->index) {
-          if (!coverStack.back()) {
-            covers++;
-            if (currDepth == 0) {
-              // We have a cover at depth 0, so everything from here on out
-              // will be covered.
-              return true;
-            }
-            coverStack.back() = true;
-          }
-        }
-      } else if (auto* otherGet = inst->origin->dynCast<LocalGet>()) {
-        if (otherGet->index == set->index && i != getIndex && !covers) {
-          // We found a get that might be a problem: it uses the same index, but
-          // is not the get we were told about, and no other set covers us.
-          return false;
-        }
-      }
-    }
-
-    // No problem.
-    return true;
-  }
-};
-
-struct OptimizeStackIR : public WalkerPass<PostWalker<OptimizeStackIR>> {
-  bool isFunctionParallel() override { return true; }
-
-  std::unique_ptr<Pass> create() override {
-    return std::make_unique<OptimizeStackIR>();
-  }
-
-  bool modifiesBinaryenIR() override { return false; }
-
-  void doWalkFunction(Function* func) {
-    if (!func->stackIR) {
-      return;
-    }
-    StackIROptimizer(func, getPassOptions(), getModule()->features).run();
-  }
-};
-
-Pass* createOptimizeStackIRPass() { return new OptimizeStackIR(); }
-
-} // namespace wasm
diff --git a/src/passes/pass.cpp b/src/passes/pass.cpp
index 4a4a9c558a8..c5a2bcc55e2 100644
--- a/src/passes/pass.cpp
+++ b/src/passes/pass.cpp
@@ -178,8 +178,6 @@ void PassRegistry::registerPasses() {
   registerPass("generate-global-effects",
                "generate global effect info (helps later passes)",
                createGenerateGlobalEffectsPass);
-  registerPass(
-    "generate-stack-ir", "generate Stack IR", createGenerateStackIRPass);
   registerPass(
     "global-refining", "refine the types of globals", createGlobalRefiningPass);
   registerPass(
@@ -321,8 +319,6 @@ void PassRegistry::registerPasses() {
   registerPass("optimize-instructions",
                "optimizes instruction combinations",
                createOptimizeInstructionsPass);
-  registerPass(
-    "optimize-stack-ir", "optimize Stack IR", createOptimizeStackIRPass);
 // Outlining currently relies on LLVM's SuffixTree, which we can't rely upon
 // when building Binaryen for Emscripten.
 #ifndef SKIP_OUTLINING
@@ -369,9 +365,6 @@ void PassRegistry::registerPasses() {
   registerPass(
     "symbolmap", "(alias for print-function-map)", createPrintFunctionMapPass);
 
-  registerPass("print-stack-ir",
-               "print out Stack IR (useful for internal debugging)",
-               createPrintStackIRPass);
   registerPass("propagate-globals-globally",
                "propagate global values to other globals (useful for tests)",
                createPropagateGlobalsGloballyPass);
@@ -736,15 +729,9 @@ void PassRunner::addDefaultGlobalOptimizationPostPasses() {
   }
   // may allow more inlining/dae/etc., need --converge for that
   addIfNoDWARFIssues("directize");
-  // perform Stack IR optimizations here, at the very end of the
-  // optimization pipeline
-  if (options.optimizeLevel >= 2 || options.shrinkLevel >= 1) {
-    addIfNoDWARFIssues("generate-stack-ir");
-    addIfNoDWARFIssues("optimize-stack-ir");
-  }
 }
 
-static void dumpWasm(Name name, Module* wasm) {
+static void dumpWasm(Name name, Module* wasm, const PassOptions& options) {
   static int counter = 0;
   std::string numstr = std::to_string(counter++);
   while (numstr.size() < 3) {
@@ -757,7 +744,7 @@ static void dumpWasm(Name name, Module* wasm) {
 #endif
   fullName += numstr + "-" + name.toString();
   Colors::setEnabled(false);
-  ModuleWriter writer;
+  ModuleWriter writer(options);
   writer.setDebugInfo(true);
   writer.writeBinary(*wasm, fullName + ".wasm");
 }
@@ -780,7 +767,7 @@ void PassRunner::run() {
       padding = std::max(padding, pass->name.size());
     }
     if (passDebug >= 3 && !isNested) {
-      dumpWasm("before", wasm);
+      dumpWasm("before", wasm, options);
     }
     for (auto& pass : passes) {
       // ignoring the time, save a printout of the module before, in case this
@@ -824,7 +811,7 @@ void PassRunner::run() {
         }
       }
       if (passDebug >= 3) {
-        dumpWasm(pass->name, wasm);
+        dumpWasm(pass->name, wasm, options);
       }
     }
     std::cerr << "[PassRunner] " << what << " took " << totalTime.count()
@@ -908,100 +895,6 @@ void PassRunner::doAdd(std::unique_ptr<Pass> pass) {
 
 void PassRunner::clear() { passes.clear(); }
 
-// Checks that the state is valid before and after a
-// pass runs on a function. We run these extra checks when
-// pass-debug mode is enabled.
-struct AfterEffectFunctionChecker {
-  Function* func;
-  Name name;
-
-  // Check Stack IR state: if the main IR changes, there should be no
-  // stack IR, as the stack IR would be wrong.
-  bool beganWithStackIR;
-  size_t originalFunctionHash;
-
-  // In the creator we can scan the state of the module and function before the
-  // pass runs.
-  AfterEffectFunctionChecker(Function* func) : func(func), name(func->name) {
-    beganWithStackIR = func->stackIR != nullptr;
-    if (beganWithStackIR) {
-      originalFunctionHash = FunctionHasher::hashFunction(func);
-    }
-  }
-
-  // This is called after the pass is run, at which time we can check things.
-  void check() {
-    assert(func->name == name); // no global module changes should have occurred
-    if (beganWithStackIR && func->stackIR) {
-      auto after = FunctionHasher::hashFunction(func);
-      if (after != originalFunctionHash) {
-        Fatal() << "[PassRunner] PASS_DEBUG check failed: had Stack IR before "
-                   "and after the pass ran, and the pass modified the main IR, "
-                   "which invalidates Stack IR - pass should have been marked "
-                   "'modifiesBinaryenIR'";
-      }
-    }
-  }
-};
-
-// Runs checks on the entire module, in a non-function-parallel pass.
-// In particular, in such a pass functions may be removed or renamed, track
-// that.
-struct AfterEffectModuleChecker {
-  Module* module;
-
-  std::vector<AfterEffectFunctionChecker> checkers;
-
-  bool beganWithAnyStackIR;
-
-  AfterEffectModuleChecker(Module* module) : module(module) {
-    for (auto& func : module->functions) {
-      checkers.emplace_back(func.get());
-    }
-    beganWithAnyStackIR = hasAnyStackIR();
-  }
-
-  void check() {
-    if (beganWithAnyStackIR && hasAnyStackIR()) {
-      // If anything changed to the functions, that's not good.
-      if (checkers.size() != module->functions.size()) {
-        error();
-      }
-      for (Index i = 0; i < checkers.size(); i++) {
-        // Did a pointer change? (a deallocated function could cause that)
-        if (module->functions[i].get() != checkers[i].func ||
-            module->functions[i]->body != checkers[i].func->body) {
-          error();
-        }
-        // Did a name change?
-        if (module->functions[i]->name != checkers[i].name) {
-          error();
-        }
-      }
-      // Global function state appears to not have been changed: the same
-      // functions are there. Look into their contents.
-      for (auto& checker : checkers) {
-        checker.check();
-      }
-    }
-  }
-
-  void error() {
-    Fatal() << "[PassRunner] PASS_DEBUG check failed: had Stack IR before and "
-               "after the pass ran, and the pass modified global function "
-               "state - pass should have been marked 'modifiesBinaryenIR'";
-  }
-
-  bool hasAnyStackIR() {
-    for (auto& func : module->functions) {
-      if (func->stackIR) {
-        return true;
-      }
-    }
-    return false;
-  }
-};
-
 void PassRunner::runPass(Pass* pass) {
   assert(!pass->isFunctionParallel());
 
@@ -1009,20 +902,12 @@ void PassRunner::runPass(Pass* pass) {
     return;
   }
 
-  std::unique_ptr<AfterEffectModuleChecker> checker;
-  if (getPassDebug()) {
-    checker = std::unique_ptr<AfterEffectModuleChecker>(
-      new AfterEffectModuleChecker(wasm));
-  }
   // Passes can only be run once and we deliberately do not clear the pass
   // runner after running the pass, so there must not already be a runner here.
   assert(!pass->getPassRunner());
   pass->setPassRunner(this);
   pass->run(wasm);
   handleAfterEffects(pass);
-  if (getPassDebug()) {
-    checker->check();
-  }
 }
 
 void PassRunner::runPassOnFunction(Pass* pass, Function* func) {
@@ -1051,21 +936,12 @@ void PassRunner::runPassOnFunction(Pass* pass, Function* func) {
     bodyBefore << *func->body << '\n';
   }
 
-  std::unique_ptr<AfterEffectFunctionChecker> checker;
-  if (passDebug) {
-    checker = std::make_unique<AfterEffectFunctionChecker>(func);
-  }
-
   // Function-parallel passes get a new instance per function
   auto instance = pass->create();
   instance->setPassRunner(this);
   instance->runOnFunction(wasm, func);
   handleAfterEffects(pass, func);
 
-  if (passDebug) {
-    checker->check();
-  }
-
   if (extraFunctionValidation) {
     if (!WasmValidator().validate(func, *wasm, WasmValidator::Minimal)) {
       Fatal() << "Last nested function-parallel pass (" << pass->name
@@ -1095,10 +971,6 @@ void PassRunner::handleAfterEffects(Pass* pass, Function* func) {
     return;
   }
 
-  // If Binaryen IR is modified, Stack IR must be cleared - it would
-  // be out of sync in a potentially dangerous way.
-  func->stackIR.reset(nullptr);
-
   if (pass->requiresNonNullableLocalFixups()) {
     TypeUpdating::handleNonDefaultableLocals(func, *wasm);
   }
diff --git a/src/passes/passes.h b/src/passes/passes.h
index 8695539b3ef..ac3e1ef299b 100644
--- a/src/passes/passes.h
+++ b/src/passes/passes.h
@@ -54,7 +54,6 @@ Pass* createFunctionMetricsPass();
 Pass* createGenerateDynCallsPass();
 Pass* createGenerateI64DynCallsPass();
 Pass* createGenerateGlobalEffectsPass();
-Pass* createGenerateStackIRPass();
 Pass* createGlobalRefiningPass();
 Pass* createGlobalStructInferencePass();
 Pass* createGlobalTypeOptimizationPass();
@@ -103,7 +102,6 @@ Pass* createOptimizeAddedConstantsPropagatePass();
 Pass* createOptimizeInstructionsPass();
 Pass* createOptimizeCastsPass();
 Pass* createOptimizeForJSPass();
-Pass* createOptimizeStackIRPass();
 // Outlining currently relies on LLVM's SuffixTree, which we can't rely upon
 // when building Binaryen for Emscripten.
 #ifdef __EMSCRIPTEN__
@@ -123,7 +121,6 @@ Pass* createPrinterPass();
 Pass* createPrintCallGraphPass();
 Pass* createPrintFeaturesPass();
 Pass* createPrintFunctionMapPass();
-Pass* createPrintStackIRPass();
 Pass* createPropagateGlobalsGloballyPass();
 Pass* createRemoveNonJSOpsPass();
 Pass* createRemoveImportsPass();
diff --git a/src/tools/optimization-options.h b/src/tools/optimization-options.h
index 0a47d9f709e..8772edd29d3 100644
--- a/src/tools/optimization-options.h
+++ b/src/tools/optimization-options.h
@@ -26,6 +26,17 @@
 namespace wasm {
 
 struct OptimizationOptions : public ToolOptions {
+  void parse(int argc, const char* argv[]) {
+    ToolOptions::parse(argc, argv);
+
+    // After parsing the arguments, update defaults based on the optimize/shrink
+    // levels.
+    if (passOptions.optimizeLevel >= 2 || passOptions.shrinkLevel >= 1) {
+      passOptions.generateStackIR = true;
+      passOptions.optimizeStackIR = true;
+    }
+  }
+
   static constexpr const char* DEFAULT_OPT_PASSES = "O";
   static constexpr const int OS_OPTIMIZE_LEVEL = 2;
   static constexpr const int OS_SHRINK_LEVEL = 1;
diff --git a/src/tools/tool-options.h b/src/tools/tool-options.h
index 6d68ff3c1ec..599b3b22cc3 100644
--- a/src/tools/tool-options.h
+++ b/src/tools/tool-options.h
@@ -151,7 +151,35 @@ struct ToolOptions : public Options {
         Options::Arguments::Zero,
         [this](Options*, const std::string&) {
           passOptions.closedWorld = true;
-        });
+        })
+      .add("--generate-stack-ir",
+           "",
+           "generate StackIR during writing",
+           ToolOptionsCategory,
+           Options::Arguments::Zero,
+           [&](Options* o, const std::string& arguments) {
+             passOptions.generateStackIR = true;
+           })
+      .add("--optimize-stack-ir",
+           "",
+           "optimize StackIR during writing",
+           ToolOptionsCategory,
+           Options::Arguments::Zero,
+           [&](Options* o, const std::string& arguments) {
+             // Also generate StackIR, to have something to optimize.
+             passOptions.generateStackIR = true;
+             passOptions.optimizeStackIR = true;
+           })
+      .add("--print-stack-ir",
+           "",
+           "print StackIR during writing",
+           ToolOptionsCategory,
+           Options::Arguments::Zero,
+           [&](Options* o, const std::string& arguments) {
+             // Also generate StackIR, to have something to print.
+             passOptions.generateStackIR = true;
+             passOptions.printStackIR = &std::cout;
+           });
   }
 
   ToolOptions& addFeature(FeatureSet::Feature feature,
diff --git a/src/tools/wasm-as.cpp b/src/tools/wasm-as.cpp
index 311605326b5..a767e6908e4 100644
--- a/src/tools/wasm-as.cpp
+++ b/src/tools/wasm-as.cpp
@@ -129,7 +129,7 @@ int main(int argc, const char* argv[]) {
   if (options.debug) {
     std::cerr << "writing..." << std::endl;
   }
-  ModuleWriter writer;
+  ModuleWriter writer(options.passOptions);
   writer.setBinary(true);
   writer.setDebugInfo(debugInfo);
   if (sourceMapFilename.size()) {
diff --git a/src/tools/wasm-ctor-eval.cpp b/src/tools/wasm-ctor-eval.cpp
index 4018be0e72a..d3f7980848d 100644
--- a/src/tools/wasm-ctor-eval.cpp
+++ b/src/tools/wasm-ctor-eval.cpp
@@ -1491,7 +1491,7 @@ int main(int argc, const char* argv[]) {
     if (options.debug) {
       std::cout << "writing..." << std::endl;
     }
-    ModuleWriter writer;
+    ModuleWriter writer(options.passOptions);
     writer.setBinary(emitBinary);
     writer.setDebugInfo(debugInfo);
     writer.write(wasm, options.extra["output"]);
diff --git a/src/tools/wasm-emscripten-finalize.cpp b/src/tools/wasm-emscripten-finalize.cpp
index a19d2732808..6b4e994ac83 100644
--- a/src/tools/wasm-emscripten-finalize.cpp
+++ b/src/tools/wasm-emscripten-finalize.cpp
@@ -279,7 +279,7 @@ int main(int argc, const char* argv[]) {
 
   if (writeOutput) {
     Output output(outfile, emitBinary ? Flags::Binary : Flags::Text);
-    ModuleWriter writer;
+    ModuleWriter writer(options.passOptions);
     writer.setDebugInfo(debugInfo);
     // writer.setSymbolMap(symbolMap);
     writer.setBinary(emitBinary);
diff --git a/src/tools/wasm-merge.cpp b/src/tools/wasm-merge.cpp
index 8e8e2d80d82..449f0cfdb40 100644
--- a/src/tools/wasm-merge.cpp
+++ b/src/tools/wasm-merge.cpp
@@ -752,7 +752,7 @@ Input source maps can be specified by adding an -ism option right after the modu
 
   // Output.
   if (options.extra.count("output") > 0) {
-    ModuleWriter writer;
+    ModuleWriter writer(options.passOptions);
     writer.setBinary(emitBinary);
     writer.setDebugInfo(debugInfo);
     if (outputSourceMapFilename.size()) {
diff --git a/src/tools/wasm-metadce.cpp b/src/tools/wasm-metadce.cpp
index 1b429a72331..3014702062f 100644
--- a/src/tools/wasm-metadce.cpp
+++ b/src/tools/wasm-metadce.cpp
@@ -600,7 +600,7 @@ int main(int argc, const char* argv[]) {
   graph.apply();
 
   if (options.extra.count("output") > 0) {
-    ModuleWriter writer;
+    ModuleWriter writer(options.passOptions);
     writer.setBinary(emitBinary);
     writer.setDebugInfo(debugInfo);
     if (outputSourceMapFilename.size()) {
diff --git a/src/tools/wasm-opt.cpp b/src/tools/wasm-opt.cpp
index 32f9f1aaddb..cb6d0bcec56 100644
--- a/src/tools/wasm-opt.cpp
+++ b/src/tools/wasm-opt.cpp
@@ -35,6 +35,7 @@
 #include "wasm-interpreter.h"
 #include "wasm-io.h"
 #include "wasm-s-parser.h"
+#include "wasm-stack.h"
 #include "wasm-validator.h"
 #include "wasm2c-wrapper.h"
 
@@ -347,7 +348,7 @@ int main(int argc, const char* argv[]) {
 
   if (extraFuzzCommand.size() > 0 && options.extra.count("output") > 0) {
     BYN_TRACE("writing binary before opts, for extra fuzz command...\n");
-    ModuleWriter writer;
+    ModuleWriter writer(options.passOptions);
     writer.setBinary(emitBinary);
     writer.setDebugInfo(options.passOptions.debugInfo);
     writer.write(wasm, options.extra["output"]);
@@ -379,7 +380,7 @@ int main(int argc, const char* argv[]) {
       // size no longer decreasing.
       auto getSize = [&]() {
         BufferWithRandomAccess buffer;
-        WasmBinaryWriter writer(&wasm, buffer);
+        WasmBinaryWriter writer(&wasm, buffer, options.passOptions);
         writer.write();
         return buffer.size();
       };
@@ -402,11 +403,6 @@ int main(int argc, const char* argv[]) {
     runner.add("translate-to-new-eh");
     // Perform Stack IR optimizations here, at the very end of the
     // optimization pipeline.
-    if (options.passOptions.optimizeLevel >= 2 ||
-        options.passOptions.shrinkLevel >= 1) {
-      runner.addIfNoDWARFIssues("generate-stack-ir");
-      runner.addIfNoDWARFIssues("optimize-stack-ir");
-    }
     runner.run();
     if (options.passOptions.validate) {
       bool valid = WasmValidator().validate(wasm, options.passOptions);
@@ -420,6 +416,10 @@ int main(int argc, const char* argv[]) {
     results.check(wasm);
   }
 
+  if (options.passOptions.printStackIR) {
+    printStackIR(std::cout, &wasm, options.passOptions);
+  }
+
   if (options.extra.count("output") == 0) {
     if (!options.quiet) {
       std::cerr << "warning: no output file specified, not emitting output\n";
@@ -428,7 +428,7 @@ int main(int argc, const char* argv[]) {
   }
 
   BYN_TRACE("writing...\n");
-  ModuleWriter writer;
+  ModuleWriter writer(options.passOptions);
   writer.setBinary(emitBinary);
   writer.setDebugInfo(options.passOptions.debugInfo);
   if (outputSourceMapFilename.size()) {
diff --git a/src/tools/wasm-reduce.cpp b/src/tools/wasm-reduce.cpp
index 094338beab7..ac5b7722bd3 100644
--- a/src/tools/wasm-reduce.cpp
+++ b/src/tools/wasm-reduce.cpp
@@ -401,7 +401,7 @@ struct Reducer
 
   bool writeAndTestReduction(ProgramResult& out) {
     // write the module out
-    ModuleWriter writer;
+    ModuleWriter writer(toolOptions.passOptions);
     writer.setBinary(binary);
     writer.setDebugInfo(debugInfo);
     writer.write(*getModule(), test);
@@ -1368,7 +1368,7 @@ int main(int argc, const char* argv[]) {
     if (resultOnInvalid == expected) {
       // Try it on a valid input.
       Module emptyModule;
-      ModuleWriter writer;
+      ModuleWriter writer(options.passOptions);
       writer.setBinary(true);
       writer.write(emptyModule, test);
       ProgramResult resultOnValid(command);
diff --git a/src/tools/wasm-split/wasm-split.cpp b/src/tools/wasm-split/wasm-split.cpp
index bea3ddce71b..d7dc19d677a 100644
--- a/src/tools/wasm-split/wasm-split.cpp
+++ b/src/tools/wasm-split/wasm-split.cpp
@@ -91,7 +91,7 @@ void adjustTableSize(Module& wasm, int initialSize) {
 void writeModule(Module& wasm,
                  std::string filename,
                  const WasmSplitOptions& options) {
-  ModuleWriter writer;
+  ModuleWriter writer(options.passOptions);
   writer.setBinary(options.emitBinary);
   writer.setDebugInfo(options.passOptions.debugInfo);
   if (options.emitModuleNames) {
diff --git a/src/wasm-binary.h b/src/wasm-binary.h
index 6c1230b7bea..b5aa83960bb 100644
--- a/src/wasm-binary.h
+++ b/src/wasm-binary.h
@@ -1270,8 +1270,10 @@ class WasmBinaryWriter {
   };
 
 public:
-  WasmBinaryWriter(Module* input, BufferWithRandomAccess& o)
-    : wasm(input), o(o), indexes(*input) {
+  WasmBinaryWriter(Module* input,
+                   BufferWithRandomAccess& o,
+                   const PassOptions& options)
+    : wasm(input), o(o), options(options), indexes(*input) {
     prepare();
   }
 
@@ -1384,6 +1386,8 @@ class WasmBinaryWriter {
 private:
   Module* wasm;
   BufferWithRandomAccess& o;
+  const PassOptions& options;
+
   BinaryIndexes indexes;
   ModuleUtils::IndexedHeapTypes indexedTypes;
   std::unordered_map<Signature, uint32_t> signatureIndexes;
diff --git a/src/wasm-io.h b/src/wasm-io.h
index ae66c39320d..e5cad9a23ff 100644
--- a/src/wasm-io.h
+++ b/src/wasm-io.h
@@ -22,6 +22,7 @@
 #define wasm_wasm_io_h
 
 #include "parsing.h"
+#include "pass.h"
 #include "support/file.h"
 #include "wasm.h"
 
@@ -85,6 +86,8 @@ class ModuleReader : public ModuleIOBase {
 };
 
 class ModuleWriter : public ModuleIOBase {
+  const PassOptions& options;
+
   bool binary = true;
 
   // TODO: Remove `emitModuleName`. See the comment in wasm-binary.h
@@ -97,7 +100,9 @@ class ModuleWriter : public ModuleIOBase {
 public:
   // Writing defaults to not storing the names section. Storing it is a user-
   // observable fact that must be opted into.
-  ModuleWriter() { setDebugInfo(false); }
+  ModuleWriter(const PassOptions& options) : options(options) {
+    setDebugInfo(false);
+  }
 
   void setBinary(bool binary_) { binary = binary_; }
   void setSymbolMap(std::string symbolMap_) { symbolMap = symbolMap_; }
diff --git a/src/wasm-stack.h b/src/wasm-stack.h
index 5858d6f88df..ae453f9de3e 100644
--- a/src/wasm-stack.h
+++ b/src/wasm-stack.h
@@ -18,6 +18,7 @@
 #define wasm_stack_h
 
 #include "ir/branch-utils.h"
+#include "ir/module-utils.h"
 #include "ir/properties.h"
 #include "pass.h"
 #include "support/insert_ordered.h"
@@ -85,6 +86,8 @@ class StackInst {
   Type type;
 };
 
+using StackIR = std::vector<StackInst*>;
+
 class BinaryInstWriter : public OverriddenVisitor<BinaryInstWriter> {
 public:
   BinaryInstWriter(WasmBinaryWriter& parent,
@@ -468,44 +471,24 @@ class BinaryenIRToBinaryWriter
   bool sourceMap;
 };
 
-// Binaryen IR to stack IR converter
-// Queues the expressions linearly in Stack IR (SIR)
-class StackIRGenerator : public BinaryenIRWriter<StackIRGenerator> {
-public:
-  StackIRGenerator(Module& module, Function* func)
-    : BinaryenIRWriter<StackIRGenerator>(func), module(module) {}
-
-  void emit(Expression* curr);
-  void emitScopeEnd(Expression* curr);
-  void emitHeader() {}
-  void emitIfElse(If* curr) {
-    stackIR.push_back(makeStackInst(StackInst::IfElse, curr));
-  }
-  void emitCatch(Try* curr, Index i) {
-    stackIR.push_back(makeStackInst(StackInst::Catch, curr));
-  }
-  void emitCatchAll(Try* curr) {
-    stackIR.push_back(makeStackInst(StackInst::CatchAll, curr));
-  }
-  void emitDelegate(Try* curr) {
-    stackIR.push_back(makeStackInst(StackInst::Delegate, curr));
-  }
-  void emitFunctionEnd() {}
-  void emitUnreachable() {
-    stackIR.push_back(makeStackInst(Builder(module).makeUnreachable()));
-  }
-  void emitDebugLocation(Expression* curr) {}
-
-  StackIR& getStackIR() { return stackIR; }
+// Binaryen IR to stack IR converter for an entire module. Generates all the
+// StackIR in parallel, and then allows querying for the StackIR of individual
+// functions.
+class ModuleStackIR {
+  ModuleUtils::ParallelFunctionAnalysis<StackIR> analysis;
 
-private:
-  StackInst* makeStackInst(StackInst::Op op, Expression* origin);
-  StackInst* makeStackInst(Expression* origin) {
-    return makeStackInst(StackInst::Basic, origin);
+public:
+  ModuleStackIR(Module& wasm, const PassOptions& options);
+
+  // Get StackIR for a function, if it exists. (This allows some functions to
+  // have it and others not, if we add such capability in the future.)
+  StackIR* getStackIROrNull(Function* func) {
+    auto iter = analysis.map.find(func);
+    if (iter == analysis.map.end()) {
+      return nullptr;
+    }
+    return &iter->second;
   }
-
-  Module& module;
-  StackIR stackIR; // filled in write()
 };
 
 // Stack IR to binary writer
@@ -514,10 +497,11 @@ class StackIRToBinaryWriter {
   StackIRToBinaryWriter(WasmBinaryWriter& parent,
                         BufferWithRandomAccess& o,
                         Function* func,
+                        StackIR& stackIR,
                         bool sourceMap = false,
                         bool DWARF = false)
     : parent(parent), writer(parent, o, func, sourceMap, DWARF), func(func),
-      sourceMap(sourceMap) {}
+      stackIR(stackIR), sourceMap(sourceMap) {}
 
   void write();
 
@@ -527,11 +511,47 @@ class StackIRToBinaryWriter {
   WasmBinaryWriter& parent;
   BinaryInstWriter writer;
   Function* func;
+  StackIR& stackIR;
   bool sourceMap;
 };
 
-std::ostream& printStackIR(std::ostream& o, Module* module, bool optimize);
+// Stack IR optimizer
+class StackIROptimizer {
+  Function* func;
+  StackIR& insts;
+  const PassOptions& passOptions;
+  FeatureSet features;
+
+public:
+  StackIROptimizer(Function* func,
+                   StackIR& insts,
+                   const PassOptions& passOptions,
+                   FeatureSet features);
+
+  void run();
+
+private:
+  void dce();
+  void vacuum();
+  void local2Stack();
+  void removeUnneededBlocks();
+  bool isControlFlowBarrier(StackInst* inst);
+  bool isControlFlowBegin(StackInst* inst);
+  bool isControlFlowEnd(StackInst* inst);
+  bool isControlFlow(StackInst* inst);
+  void removeAt(Index i);
+  Index getNumConsumedValues(StackInst* inst);
+  bool canRemoveSetGetPair(Index setIndex, Index getIndex);
+};
+
+// Generate and emit StackIR.
+std::ostream&
+printStackIR(std::ostream& o, Module* module, const PassOptions& options);
 
 } // namespace wasm
 
+namespace std {
+std::ostream& operator<<(std::ostream& o, wasm::StackInst& inst);
+} // namespace std
+
 #endif // wasm_stack_h
diff --git a/src/wasm.h b/src/wasm.h
index d852950e8b3..ebc7b908d60 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -2136,14 +2136,6 @@ struct BinaryLocations {
   std::unordered_map<Function*, FunctionLocations> functions;
 };
 
-// Forward declarations of Stack IR, as functions can contain it, see
-// the stackIR property.
-// Stack IR is a secondary IR to the main IR defined in this file (Binaryen
-// IR). See wasm-stack.h.
-class StackInst;
-
-using StackIR = std::vector<StackInst*>;
-
 class Function : public Importable {
 public:
   HeapType type = HeapType(Signature()); // parameters and return value
@@ -2153,16 +2145,6 @@ class Function : public Importable {
   // The body of the function
   Expression* body = nullptr;
 
-  // If present, this stack IR was generated from the main Binaryen IR body,
-  // and possibly optimized. If it is present when writing to wasm binary,
-  // it will be emitted instead of the main Binaryen IR.
-  //
-  // Note that no special care is taken to synchronize the two IRs - if you
-  // emit stack IR and then optimize the main IR, you need to recompute the
-  // stack IR. The Pass system will throw away Stack IR if a pass is run
-  // that declares it may modify Binaryen IR.
-  std::unique_ptr<StackIR> stackIR;
-
   // local names. these are optional.
   std::unordered_map<Index, Name> localNames;
   std::unordered_map<Name, Index> localIndices;
@@ -2511,8 +2493,6 @@ std::ostream& operator<<(std::ostream& o, wasm::Function& func);
 std::ostream& operator<<(std::ostream& o, wasm::Expression& expression);
 std::ostream& operator<<(std::ostream& o, wasm::ModuleExpression pair);
 std::ostream& operator<<(std::ostream& o, wasm::ShallowExpression expression);
-std::ostream& operator<<(std::ostream& o, wasm::StackInst& inst);
-std::ostream& operator<<(std::ostream& o, wasm::StackIR& ir);
 
 } // namespace std
 
diff --git a/src/wasm/CMakeLists.txt b/src/wasm/CMakeLists.txt
index d5b4f674741..e01be3b6a79 100644
--- a/src/wasm/CMakeLists.txt
+++ b/src/wasm/CMakeLists.txt
@@ -11,6 +11,7 @@ set(wasm_SOURCES
   wasm-ir-builder.cpp
   wasm-s-parser.cpp
   wasm-stack.cpp
+  wasm-stack-opts.cpp
   wasm-type.cpp
   wasm-validator.cpp
   ${wasm_HEADERS}
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index d4fda5915b1..7e90dfde4d3 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -392,6 +392,12 @@ void WasmBinaryWriter::writeFunctions() {
   if (importInfo->getNumDefinedFunctions() == 0) {
     return;
   }
+
+  std::optional<ModuleStackIR> moduleStackIR;
+  if (options.generateStackIR) {
+    moduleStackIR.emplace(*wasm, options);
+  }
+
   BYN_TRACE("== writeFunctions\n");
   auto sectionStart = startSection(BinaryConsts::Section::Code);
   o << U32LEB(importInfo->getNumDefinedFunctions());
@@ -405,10 +411,14 @@ void WasmBinaryWriter::writeFunctions() {
     size_t sizePos = writeU32LEBPlaceholder();
     size_t start = o.size();
     BYN_TRACE("writing" << func->name << std::endl);
-    // Emit Stack IR if present, and if we can
-    if (func->stackIR) {
+    // Emit Stack IR if present.
+    StackIR* stackIR = nullptr;
+    if (moduleStackIR) {
+      stackIR = moduleStackIR->getStackIROrNull(func);
+    }
+    if (stackIR) {
       BYN_TRACE("write Stack IR\n");
-      StackIRToBinaryWriter writer(*this, o, func, sourceMap, DWARF);
+      StackIRToBinaryWriter writer(*this, o, func, *stackIR, sourceMap, DWARF);
       writer.write();
       if (debugInfo) {
         funcMappedLocals[func->name] = std::move(writer.getMappedLocals());
diff --git a/src/wasm/wasm-io.cpp b/src/wasm/wasm-io.cpp
index a24122bd8d6..10b84bb4dd0 100644
--- a/src/wasm/wasm-io.cpp
+++ b/src/wasm/wasm-io.cpp
@@ -149,7 +149,7 @@ void ModuleWriter::writeText(Module& wasm, std::string filename) {
 
 void ModuleWriter::writeBinary(Module& wasm, Output& output) {
   BufferWithRandomAccess buffer;
-  WasmBinaryWriter writer(&wasm, buffer);
+  WasmBinaryWriter writer(&wasm, buffer, options);
   // if debug info is used, then we want to emit the names section
   writer.setNamesSection(debugInfo);
   if (emitModuleName) {
diff --git a/src/wasm/wasm-stack-opts.cpp b/src/wasm/wasm-stack-opts.cpp
new file mode 100644
index 00000000000..eac423fbd18
--- /dev/null
+++ b/src/wasm/wasm-stack-opts.cpp
@@ -0,0 +1,456 @@
+/*
+ * Copyright 2018 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//
+// Operations on Stack IR.
+//
+
+#include "ir/iteration.h"
+#include "ir/local-graph.h"
+#include "pass.h"
+#include "wasm-stack.h"
+#include "wasm.h"
+
+namespace wasm {
+
+StackIROptimizer::StackIROptimizer(Function* func,
+                                   StackIR& insts,
+                                   const PassOptions& passOptions,
+                                   FeatureSet features)
+  : func(func), insts(insts), passOptions(passOptions), features(features) {}
+
+void StackIROptimizer::run() {
+  dce();
+  // FIXME: local2Stack is currently rather slow (due to localGraph),
+  //        so for now run it only when really optimizing
+  if (passOptions.optimizeLevel >= 3 || passOptions.shrinkLevel >= 1) {
+    local2Stack();
+  }
+  removeUnneededBlocks();
+  dce();
+  vacuum();
+}
+
+// Remove unreachable code.
+void StackIROptimizer::dce() {
+  bool inUnreachableCode = false;
+  for (Index i = 0; i < insts.size(); i++) {
+    auto* inst = insts[i];
+    if (!inst) {
+      continue;
+    }
+    if (inUnreachableCode) {
+      // Does the unreachable code end here?
+      if (isControlFlowBarrier(inst)) {
+        inUnreachableCode = false;
+      } else {
+        // We can remove this.
+        removeAt(i);
+      }
+    } else if (inst->type == Type::unreachable) {
+      inUnreachableCode = true;
+    }
+  }
+}
+
+// Remove obviously-unneeded code.
+void StackIROptimizer::vacuum() {
+  // In the wasm binary format a nop is never needed. (In Binaryen IR, in
+  // comparison, it is necessary e.g. in a function body or an if arm.)
+  //
+  // It is especially important to remove nops because we add nops when we
+  // read wasm into Binaryen IR. That is, this avoids a potential increase in
+  // code size.
+  for (Index i = 0; i < insts.size(); i++) {
+    auto*& inst = insts[i];
+    if (inst && inst->origin->is<Nop>()) {
+      inst = nullptr;
+    }
+  }
+}
+
+// If ordered properly, we can avoid a local.set/local.get pair,
+// and use the value directly from the stack, for example
+//    [..produce a value on the stack..]
+//    local.set $x
+//    [..much code..]
+//    local.get $x
+//    call $foo ;; use the value, foo(value)
+// As long as the code in between does not modify $x, and has
+// no control flow branching out, we can remove both the set
+// and the get.
+void StackIROptimizer::local2Stack() {
+  // We use the localGraph to tell us if a get-set pair is indeed
+  // a set that is read by that get, and only that get. Note that we run
+  // this on the Binaryen IR, so we are assuming that no previous opt
+  // has changed the interaction of local operations.
+  // TODO: we can do this a lot faster, as we just care about linear
+  //       control flow.
+  LocalGraph localGraph(func);
+  localGraph.computeSetInfluences();
+  // We maintain a stack of relevant values. This contains:
+  //  * a null for each actual value that the value stack would have
+  //  * an index of each LocalSet that *could* be on the value
+  //    stack at that location.
+  const Index null = -1;
+  std::vector<Index> values;
+  // We also maintain a stack of values vectors for control flow,
+  // saving the stack as we enter and restoring it when we exit.
+  std::vector<std::vector<Index>> savedValues;
+#ifdef STACK_OPT_DEBUG
+  std::cout << "func: " << func->name << '\n' << insts << '\n';
+#endif
+  for (Index instIndex = 0; instIndex < insts.size(); instIndex++) {
+    auto* inst = insts[instIndex];
+    if (!inst) {
+      continue;
+    }
+    // First, consume values from the stack as required.
+    auto consumed = getNumConsumedValues(inst);
+#ifdef STACK_OPT_DEBUG
+    std::cout << "  " << instIndex << " : " << *inst << ", " << values.size()
+              << " on stack, will consume " << consumed << "\n    ";
+    for (auto s : values)
+      std::cout << s << ' ';
+    std::cout << '\n';
+#endif
+    // TODO: currently we run dce before this, but if we didn't, we'd need
+    //       to handle unreachable code here - it's ok to pop multiple values
+    //       there even if the stack is at size 0.
+    while (consumed > 0) {
+      assert(values.size() > 0);
+      // Whenever we hit a possible stack value, kill it - it would
+      // be consumed here, so we can never optimize to it.
+      while (values.back() != null) {
+        values.pop_back();
+        assert(values.size() > 0);
+      }
+      // Finally, consume the actual value that is consumed here.
+      values.pop_back();
+      consumed--;
+    }
+    // After consuming, we can see what to do with this. First, handle
+    // control flow.
+    if (isControlFlowBegin(inst)) {
+      // Save the stack for when we end this control flow.
+      savedValues.push_back(values); // TODO: optimize copies
+      values.clear();
+    } else if (isControlFlowEnd(inst)) {
+      assert(!savedValues.empty());
+      values = savedValues.back();
+      savedValues.pop_back();
+    } else if (isControlFlow(inst)) {
+      // Otherwise, in the middle of control flow, just clear it
+      values.clear();
+    }
+    // This is something we should handle, look into it.
+    if (inst->type.isConcrete()) {
+      bool optimized = false;
+      // Do not optimize multivalue locals, since those will be better
+      // optimized when they are visited in the binary writer and this
+      // optimization would intefere with that one.
+      if (auto* get = inst->origin->dynCast<LocalGet>();
+          get && inst->type.isSingle()) {
+        // Use another local to clarify what instIndex means in this scope.
+        auto getIndex = instIndex;
+
+        // This is a potential optimization opportunity! See if we
+        // can reach the set.
+        if (values.size() > 0) {
+          Index j = values.size() - 1;
+          while (1) {
+            // If there's an actual value in the way, we've failed.
+            auto setIndex = values[j];
+            if (setIndex == null) {
+              break;
+            }
+            auto* set = insts[setIndex]->origin->cast<LocalSet>();
+            if (set->index == get->index) {
+              // This might be a proper set-get pair, where the set is
+              // used by this get and nothing else, check that.
+              auto& sets = localGraph.getSetses[get];
+              if (sets.size() == 1 && *sets.begin() == set) {
+                auto& setInfluences = localGraph.setInfluences[set];
+                // If this has the proper value of 1, also do the potentially-
+                // expensive check of whether we can remove this pair at all.
+                if (setInfluences.size() == 1 &&
+                    canRemoveSetGetPair(setIndex, getIndex)) {
+                  assert(*setInfluences.begin() == get);
+                  // Do it! The set and the get can go away, the proper
+                  // value is on the stack.
+#ifdef STACK_OPT_DEBUG
+                  std::cout << "  stackify the get\n";
+#endif
+                  insts[setIndex] = nullptr;
+                  insts[getIndex] = nullptr;
+                  // Continuing on from here, replace this on the stack
+                  // with a null, representing a regular value. We
+                  // keep possible values above us active - they may
+                  // be optimized later, as they would be pushed after
+                  // us, and used before us, so there is no conflict.
+                  values[j] = null;
+                  optimized = true;
+                  break;
+                }
+              }
+            }
+            // We failed here. Can we look some more?
+            if (j == 0) {
+              break;
+            }
+            j--;
+          }
+        }
+      }
+      if (!optimized) {
+        // This is an actual regular value on the value stack.
+        values.push_back(null);
+      }
+    } else if (inst->origin->is<LocalSet>() && inst->type == Type::none) {
+      // This set is potentially optimizable later, add to stack.
+      values.push_back(instIndex);
+    }
+  }
+}
+
+// There may be unnecessary blocks we can remove: blocks
+// without branches to them are always ok to remove.
+// TODO: a branch to a block in an if body can become
+//       a branch to that if body
+void StackIROptimizer::removeUnneededBlocks() {
+  for (auto*& inst : insts) {
+    if (!inst) {
+      continue;
+    }
+    if (auto* block = inst->origin->dynCast<Block>()) {
+      if (!BranchUtils::BranchSeeker::has(block, block->name)) {
+        // TODO optimize, maybe run remove-unused-names
+        inst = nullptr;
+      }
+    }
+  }
+}
+
+// A control flow "barrier" - a point where stack machine
+// unreachability ends.
+bool StackIROptimizer::isControlFlowBarrier(StackInst* inst) {
+  switch (inst->op) {
+    case StackInst::BlockEnd:
+    case StackInst::IfElse:
+    case StackInst::IfEnd:
+    case StackInst::LoopEnd:
+    case StackInst::Catch:
+    case StackInst::CatchAll:
+    case StackInst::Delegate:
+    case StackInst::TryEnd:
+    case StackInst::TryTableEnd: {
+      return true;
+    }
+    default: {
+      return false;
+    }
+  }
+}
+
+// A control flow beginning.
+bool StackIROptimizer::isControlFlowBegin(StackInst* inst) {
+  switch (inst->op) {
+    case StackInst::BlockBegin:
+    case StackInst::IfBegin:
+    case StackInst::LoopBegin:
+    case StackInst::TryBegin:
+    case StackInst::TryTableBegin: {
+      return true;
+    }
+    default: {
+      return false;
+    }
+  }
+}
+
+// A control flow ending.
+bool StackIROptimizer::isControlFlowEnd(StackInst* inst) {
+  switch (inst->op) {
+    case StackInst::BlockEnd:
+    case StackInst::IfEnd:
+    case StackInst::LoopEnd:
+    case StackInst::TryEnd:
+    case StackInst::Delegate:
+    case StackInst::TryTableEnd: {
+      return true;
+    }
+    default: {
+      return false;
+    }
+  }
+}
+
+bool StackIROptimizer::isControlFlow(StackInst* inst) {
+  return inst->op != StackInst::Basic;
+}
+
+// Remove the instruction at index i. If the instruction
+// is control flow, and so has been expanded to multiple
+// instructions, remove them as well.
+void StackIROptimizer::removeAt(Index i) {
+  auto* inst = insts[i];
+  insts[i] = nullptr;
+  if (inst->op == StackInst::Basic) {
+    return; // that was it
+  }
+  auto* origin = inst->origin;
+  while (1) {
+    i++;
+    assert(i < insts.size());
+    inst = insts[i];
+    insts[i] = nullptr;
+    if (inst && inst->origin == origin && isControlFlowEnd(inst)) {
+      return; // that's it, we removed it all
+    }
+  }
+}
+
+Index StackIROptimizer::getNumConsumedValues(StackInst* inst) {
+  if (isControlFlow(inst)) {
+    // If consumes 1; that's it.
+    if (inst->op == StackInst::IfBegin) {
+      return 1;
+    }
+    return 0;
+  }
+  // Otherwise, for basic instructions, just count the expression children.
+  return ChildIterator(inst->origin).children.size();
+}
+
+// Given a pair of a local.set and local.get, see if we can remove them
+// without breaking validation. Specifically, we must keep sets of non-
+// nullable locals that dominate a get until the end of the block, such as
+// here:
+//
+//  local.set 0    ;; Can we remove
+//  local.get 0    ;; this pair?
+//  if
+//    local.set 0
+//  else
+//    local.set 0
+//  end
+//  local.get 0    ;; This get poses a problem.
+//
+// Logically the 2nd&3rd sets ensure a value is applied to the local before we
+// read it, but the validation rules only track each set until the end of its
+// scope, so the 1st set (before the if, in the pair) is necessary.
+//
+// The logic below is related to LocalStructuralDominance, but sharing code
+// with it is difficult as this uses StackIR and not BinaryenIR, and it checks
+// a particular set/get pair.
+//
+// We are given the indexes of the set and get instructions in |insts|.
+bool StackIROptimizer::canRemoveSetGetPair(Index setIndex, Index getIndex) {
+  // The set must be before the get.
+  assert(setIndex < getIndex);
+
+  auto* set = insts[setIndex]->origin->cast<LocalSet>();
+  auto localType = func->getLocalType(set->index);
+  // Note we do not need to handle tuples here, as the parent ignores them
+  // anyhow (hence we can check non-nullability instead of non-
+  // defaultability).
+  assert(localType.isSingle());
+  if (func->isParam(set->index) || !localType.isNonNullable()) {
+    // This local cannot pose a problem for validation (params are always
+    // initialized, and it is ok if nullable locals are uninitialized).
+    return true;
+  }
+
+  // Track the depth (in block/if/loop/etc. scopes) relative to our starting
+  // point. Anything less deep than that is not interesting, as we can only
+  // help things at our depth or deeper to validate.
+  Index currDepth = 0;
+
+  // Look for a different get than the one in getIndex (since that one is
+  // being removed) which would stop validating without the set. While doing
+  // so, note other sets that ensure validation even if our set is removed. We
+  // track those in this stack of booleans, one for each scope, which is true
+  // if another sets covers us and ours is not needed.
+  //
+  // We begin in the current scope and with no other set covering us.
+  std::vector<bool> coverStack = {false};
+
+  // Track the total number of covers as well, for quick checking below.
+  Index covers = 0;
+
+  // TODO: We could look before us as well, but then we might end up scanning
+  //       much of the function every time.
+  for (Index i = setIndex + 1; i < insts.size(); i++) {
+    auto* inst = insts[i];
+    if (!inst) {
+      continue;
+    }
+    if (isControlFlowBegin(inst)) {
+      // A new scope begins.
+      currDepth++;
+      coverStack.push_back(false);
+    } else if (isControlFlowEnd(inst)) {
+      if (currDepth == 0) {
+        // Less deep than the start, so we found no problem.
+        return true;
+      }
+      currDepth--;
+
+      if (coverStack.back()) {
+        // A cover existed in the scope which ended.
+        covers--;
+      }
+      coverStack.pop_back();
+    } else if (isControlFlowBarrier(inst)) {
+      // A barrier, like the else in an if-else, not only ends a scope but
+      // opens a new one.
+      if (currDepth == 0) {
+        // Another scope with the same depth begins, but ours ended, so stop.
+        return true;
+      }
+
+      if (coverStack.back()) {
+        // A cover existed in the scope which ended.
+        covers--;
+      }
+      coverStack.back() = false;
+    } else if (auto* otherSet = inst->origin->dynCast<LocalSet>()) {
+      // We are covered in this scope henceforth.
+      if (otherSet->index == set->index) {
+        if (!coverStack.back()) {
+          covers++;
+          if (currDepth == 0) {
+            // We have a cover at depth 0, so everything from here on out
+            // will be covered.
+            return true;
+          }
+          coverStack.back() = true;
+        }
+      }
+    } else if (auto* otherGet = inst->origin->dynCast<LocalGet>()) {
+      if (otherGet->index == set->index && i != getIndex && !covers) {
+        // We found a get that might be a problem: it uses the same index, but
+        // is not the get we were told about, and no other set covers us.
+        return false;
+      }
+    }
+  }
+
+  // No problem.
+  return true;
+}
+
+} // namespace wasm
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 1ed60abedc0..3cdd1f71814 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -2737,6 +2737,45 @@ int32_t BinaryInstWriter::getBreakIndex(Name name) { // -1 if not found
   WASM_UNREACHABLE("break index not found");
 }
 
+// Queues the expressions linearly in Stack IR (SIR)
+class StackIRGenerator : public BinaryenIRWriter<StackIRGenerator> {
+public:
+  StackIRGenerator(Module& module, Function* func)
+    : BinaryenIRWriter<StackIRGenerator>(func), module(module) {}
+
+  void emit(Expression* curr);
+  void emitScopeEnd(Expression* curr);
+  void emitHeader() {}
+  void emitIfElse(If* curr) {
+    stackIR.push_back(makeStackInst(StackInst::IfElse, curr));
+  }
+  void emitCatch(Try* curr, Index i) {
+    stackIR.push_back(makeStackInst(StackInst::Catch, curr));
+  }
+  void emitCatchAll(Try* curr) {
+    stackIR.push_back(makeStackInst(StackInst::CatchAll, curr));
+  }
+  void emitDelegate(Try* curr) {
+    stackIR.push_back(makeStackInst(StackInst::Delegate, curr));
+  }
+  void emitFunctionEnd() {}
+  void emitUnreachable() {
+    stackIR.push_back(makeStackInst(Builder(module).makeUnreachable()));
+  }
+  void emitDebugLocation(Expression* curr) {}
+
+  StackIR& getStackIR() { return stackIR; }
+
+private:
+  StackInst* makeStackInst(StackInst::Op op, Expression* origin);
+  StackInst* makeStackInst(Expression* origin) {
+    return makeStackInst(StackInst::Basic, origin);
+  }
+
+  Module& module;
+  StackIR stackIR; // filled in write()
+};
+
 void StackIRGenerator::emit(Expression* curr) {
   StackInst* stackInst = nullptr;
   if (curr->is<Block>()) {
@@ -2798,6 +2837,22 @@ StackInst* StackIRGenerator::makeStackInst(StackInst::Op op,
   return ret;
 }
 
+ModuleStackIR::ModuleStackIR(Module& wasm, const PassOptions& options)
+  : analysis(wasm, [&](Function* func, StackIR& stackIR) {
+      if (func->imported()) {
+        return;
+      }
+
+      StackIRGenerator stackIRGen(wasm, func);
+      stackIRGen.write();
+      stackIR = std::move(stackIRGen.getStackIR());
+
+      if (options.optimizeStackIR) {
+        StackIROptimizer optimizer(func, stackIR, options, wasm.features);
+        optimizer.run();
+      }
+    }) {}
+
 void StackIRToBinaryWriter::write() {
   if (func->prologLocation.size()) {
     parent.writeDebugLocation(*func->prologLocation.begin());
@@ -2805,7 +2860,7 @@ void StackIRToBinaryWriter::write() {
   writer.mapLocalsAndEmitHeader();
   // Stack to track indices of catches within a try
   SmallVector<Index, 4> catchIndexStack;
-  for (auto* inst : *func->stackIR) {
+  for (auto* inst : stackIR) {
     if (!inst) {
       continue; // a nullptr is just something we can skip
     }
diff --git a/test/binaryen.js/hello-world.js.txt b/test/binaryen.js/hello-world.js.txt
index 3f9296adfcc..70c94764a53 100644
--- a/test/binaryen.js/hello-world.js.txt
+++ b/test/binaryen.js/hello-world.js.txt
@@ -16,7 +16,7 @@ optimized:
 (module
  (type $0 (func (param i32 i32) (result i32)))
  (export "adder" (func $adder))
- (func $adder (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+ (func $adder (param $0 i32) (param $1 i32) (result i32)
   (i32.add
    (local.get $0)
    (local.get $1)
diff --git a/test/binaryen.js/low-memory-unused.js.txt b/test/binaryen.js/low-memory-unused.js.txt
index 99c68225904..d9b10a3f629 100644
--- a/test/binaryen.js/low-memory-unused.js.txt
+++ b/test/binaryen.js/low-memory-unused.js.txt
@@ -32,7 +32,7 @@
  (type $0 (func (param i32) (result i32)))
  (memory $0 1)
  (export "test" (func $test))
- (func $test (; has Stack IR ;) (param $0 i32) (result i32)
+ (func $test (param $0 i32) (result i32)
   (i32.load
    (i32.add
     (local.get $0)
@@ -48,7 +48,7 @@
  (type $0 (func (param i32) (result i32)))
  (memory $0 1)
  (export "test" (func $test))
- (func $test (; has Stack IR ;) (param $0 i32) (result i32)
+ (func $test (param $0 i32) (result i32)
   (i32.load offset=128
    (local.get $0)
   )
diff --git a/test/binaryen.js/optimize-levels.js.txt b/test/binaryen.js/optimize-levels.js.txt
index ed928fbef15..4e2902079b3 100644
--- a/test/binaryen.js/optimize-levels.js.txt
+++ b/test/binaryen.js/optimize-levels.js.txt
@@ -38,7 +38,7 @@ shrinkLevel=1
 (module
  (type $i (func (param i32) (result i32)))
  (export "test" (func $test))
- (func $test (; has Stack IR ;) (param $0 i32) (result i32)
+ (func $test (param $0 i32) (result i32)
   (local.get $0)
  )
 )
@@ -60,7 +60,7 @@ shrinkLevel=1
 (module
  (type $i (func (param i32) (result i32)))
  (export "test" (func $test))
- (func $test (; has Stack IR ;) (param $0 i32) (result i32)
+ (func $test (param $0 i32) (result i32)
   (local.get $0)
  )
 )
diff --git a/test/binaryen.js/sieve.js.txt b/test/binaryen.js/sieve.js.txt
index 46e5d3b398c..e04b0bfe175 100644
--- a/test/binaryen.js/sieve.js.txt
+++ b/test/binaryen.js/sieve.js.txt
@@ -62,7 +62,7 @@ optimized:
  (type $0 (func (param i32) (result i32)))
  (memory $0 1 100)
  (export "sieve" (func $sieve))
- (func $sieve (; has Stack IR ;) (param $0 i32) (result i32)
+ (func $sieve (param $0 i32) (result i32)
   (local $1 i32)
   (if
    (i32.lt_u
diff --git a/test/binaryen.js/stackir.js b/test/binaryen.js/stackir.js
index d797aa6d818..dd503a53da4 100644
--- a/test/binaryen.js/stackir.js
+++ b/test/binaryen.js/stackir.js
@@ -26,4 +26,5 @@ console.log("=== default ===");
 console.log(module.emitStackIR());
 
 console.log("=== optimize ==="); // should omit the second block
-console.log(module.emitStackIR(true));
+binaryen.setOptimizeLevel(2);
+console.log(module.emitStackIR());
diff --git a/test/example/c-api-kitchen-sink.c b/test/example/c-api-kitchen-sink.c
index e5b614becbe..66cf43290f7 100644
--- a/test/example/c-api-kitchen-sink.c
+++ b/test/example/c-api-kitchen-sink.c
@@ -2008,12 +2008,17 @@ void test_binaries() {
   BinaryenModuleWriteText(module, buffer, 1024);
   printf("module s-expr printed (in memory):\n%s\n", buffer);
 
-  // writ the s-expr representation to a pointer which is managed by the
+  // write the s-expr representation to a pointer which is managed by the
   // caller
   char* text = BinaryenModuleAllocateAndWriteText(module);
   printf("module s-expr printed (in memory, caller-owned):\n%s\n", text);
   free(text);
 
+  // write StackIR
+  text = BinaryenModuleAllocateAndWriteStackIR(module);
+  printf("module s-expr printed (StackIR):\n%s\n", text);
+  free(text);
+
   BinaryenModuleDispose(module);
 }
 
diff --git a/test/example/c-api-kitchen-sink.txt b/test/example/c-api-kitchen-sink.txt
index 8bdf1ba52ea..fe784a453aa 100644
--- a/test/example/c-api-kitchen-sink.txt
+++ b/test/example/c-api-kitchen-sink.txt
@@ -3140,6 +3140,16 @@ module s-expr printed (in memory, caller-owned):
  )
 )
 
+module s-expr printed (StackIR):
+(module
+ (type $0 (func (param i32 i32) (result i32)))
+ (func $adder (param $0 i32) (param $1 i32) (result i32)
+  local.get $0
+  local.get $1
+  i32.add
+ )
+)
+
 (module
  (type $0 (func (param i32)))
  (type $1 (func))
diff --git a/test/example/relooper-fuzz.txt b/test/example/relooper-fuzz.txt
index 1030fac320d..e4c3f6db4ce 100644
--- a/test/example/relooper-fuzz.txt
+++ b/test/example/relooper-fuzz.txt
@@ -311,7 +311,7 @@
  (memory $0 1 1)
  (export "mem" (memory $0))
  (start $main)
- (func $check (; has Stack IR ;) (result i32)
+ (func $check (result i32)
   (if
    (i32.eq
     (i32.load
@@ -348,7 +348,7 @@
    )
   )
  )
- (func $main (; has Stack IR ;)
+ (func $main
   (local $0 i32)
   (local $1 i32)
   (i32.store
diff --git a/test/example/relooper-fuzz1.txt b/test/example/relooper-fuzz1.txt
index 3cdb12e69f1..675d5104260 100644
--- a/test/example/relooper-fuzz1.txt
+++ b/test/example/relooper-fuzz1.txt
@@ -293,7 +293,7 @@
  (memory $0 1 1)
  (export "mem" (memory $0))
  (start $main)
- (func $check (; has Stack IR ;) (result i32)
+ (func $check (result i32)
   (if
    (i32.eq
     (i32.load
@@ -330,7 +330,7 @@
    )
   )
  )
- (func $main (; has Stack IR ;)
+ (func $main
   (local $0 i32)
   (i32.store
    (i32.const 8)
diff --git a/test/lit/help/wasm-as.test b/test/lit/help/wasm-as.test
index bf12fc1cf57..09e5b7c9da2 100644
--- a/test/lit/help/wasm-as.test
+++ b/test/lit/help/wasm-as.test
@@ -126,6 +126,12 @@
 ;; CHECK-NEXT:                                        them and pass them back in, but not
 ;; CHECK-NEXT:                                        inspect their contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                  generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                  optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                     print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm-ctor-eval.test b/test/lit/help/wasm-ctor-eval.test
index bbf8e1daa3c..e511ef0b9a2 100644
--- a/test/lit/help/wasm-ctor-eval.test
+++ b/test/lit/help/wasm-ctor-eval.test
@@ -133,6 +133,12 @@
 ;; CHECK-NEXT:                                        them and pass them back in, but not
 ;; CHECK-NEXT:                                        inspect their contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                  generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                  optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                     print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm-dis.test b/test/lit/help/wasm-dis.test
index f1f8283c8a4..2dffcc945d9 100644
--- a/test/lit/help/wasm-dis.test
+++ b/test/lit/help/wasm-dis.test
@@ -119,6 +119,12 @@
 ;; CHECK-NEXT:                                        them and pass them back in, but not
 ;; CHECK-NEXT:                                        inspect their contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                  generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                  optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                     print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm-emscripten-finalize.test b/test/lit/help/wasm-emscripten-finalize.test
index 8666c2ea122..a4ba48b1608 100644
--- a/test/lit/help/wasm-emscripten-finalize.test
+++ b/test/lit/help/wasm-emscripten-finalize.test
@@ -161,6 +161,12 @@
 ;; CHECK-NEXT:                                        them and pass them back in, but not
 ;; CHECK-NEXT:                                        inspect their contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                  generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                  optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                     print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm-merge.test b/test/lit/help/wasm-merge.test
index 997923256ef..c87be5edf1a 100644
--- a/test/lit/help/wasm-merge.test
+++ b/test/lit/help/wasm-merge.test
@@ -149,6 +149,12 @@
 ;; CHECK-NEXT:                                        them and pass them back in, but not
 ;; CHECK-NEXT:                                        inspect their contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                  generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                  optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                     print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm-metadce.test b/test/lit/help/wasm-metadce.test
index 4d706dc0f1d..f0889eb81f7 100644
--- a/test/lit/help/wasm-metadce.test
+++ b/test/lit/help/wasm-metadce.test
@@ -174,6 +174,12 @@
 ;; CHECK-NEXT:                                        them and pass them back in, but not
 ;; CHECK-NEXT:                                        inspect their contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                  generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                  optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                     print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm-opt.test b/test/lit/help/wasm-opt.test
index f7ee47c09f6..f6497618e65 100644
--- a/test/lit/help/wasm-opt.test
+++ b/test/lit/help/wasm-opt.test
@@ -182,8 +182,6 @@
 ;; CHECK-NEXT:                                                 without JavaScript BigInt
 ;; CHECK-NEXT:                                                 support).
 ;; CHECK-NEXT:
-;; CHECK-NEXT:   --generate-stack-ir                           generate Stack IR
-;; CHECK-NEXT:
 ;; CHECK-NEXT:   --global-refining                             refine the types of globals
 ;; CHECK-NEXT:
 ;; CHECK-NEXT:   --gsi                                         globally optimize struct values
@@ -333,8 +331,6 @@
 ;; CHECK-NEXT:   --optimize-j2cl                               optimizes J2CL specific
 ;; CHECK-NEXT:                                                 constructs.
 ;; CHECK-NEXT:
-;; CHECK-NEXT:   --optimize-stack-ir                           optimize Stack IR
-;; CHECK-NEXT:
 ;; CHECK-NEXT:   --outlining                                   outline instructions
 ;; CHECK-NEXT:
 ;; CHECK-NEXT:   --pick-load-signs                             pick load signs based on their
@@ -369,9 +365,6 @@
 ;; CHECK-NEXT:   --print-minified                              print in minified s-expression
 ;; CHECK-NEXT:                                                 format
 ;; CHECK-NEXT:
-;; CHECK-NEXT:   --print-stack-ir                              print out Stack IR (useful for
-;; CHECK-NEXT:                                                 internal debugging)
-;; CHECK-NEXT:
 ;; CHECK-NEXT:   --propagate-debug-locs                        propagate debug location from
 ;; CHECK-NEXT:                                                 parents or previous siblings to
 ;; CHECK-NEXT:                                                 child nodes
@@ -746,6 +739,12 @@
 ;; CHECK-NEXT:                                                 in, but not inspect their
 ;; CHECK-NEXT:                                                 contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                           generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                           optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                              print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm-reduce.test b/test/lit/help/wasm-reduce.test
index e28894e4acf..a98b8a1995b 100644
--- a/test/lit/help/wasm-reduce.test
+++ b/test/lit/help/wasm-reduce.test
@@ -155,6 +155,12 @@
 ;; CHECK-NEXT:                                        them and pass them back in, but not
 ;; CHECK-NEXT:                                        inspect their contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                  generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                  optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                     print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm-split.test b/test/lit/help/wasm-split.test
index e7b287fcc01..fcd919ea88d 100644
--- a/test/lit/help/wasm-split.test
+++ b/test/lit/help/wasm-split.test
@@ -235,6 +235,12 @@
 ;; CHECK-NEXT:                                        them and pass them back in, but not
 ;; CHECK-NEXT:                                        inspect their contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                  generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                  optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                     print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/help/wasm2js.test b/test/lit/help/wasm2js.test
index 4b0330db6a1..13e93c33b92 100644
--- a/test/lit/help/wasm2js.test
+++ b/test/lit/help/wasm2js.test
@@ -132,8 +132,6 @@
 ;; CHECK-NEXT:                                                 without JavaScript BigInt
 ;; CHECK-NEXT:                                                 support).
 ;; CHECK-NEXT:
-;; CHECK-NEXT:   --generate-stack-ir                           generate Stack IR
-;; CHECK-NEXT:
 ;; CHECK-NEXT:   --global-refining                             refine the types of globals
 ;; CHECK-NEXT:
 ;; CHECK-NEXT:   --gsi                                         globally optimize struct values
@@ -283,8 +281,6 @@
 ;; CHECK-NEXT:   --optimize-j2cl                               optimizes J2CL specific
 ;; CHECK-NEXT:                                                 constructs.
 ;; CHECK-NEXT:
-;; CHECK-NEXT:   --optimize-stack-ir                           optimize Stack IR
-;; CHECK-NEXT:
 ;; CHECK-NEXT:   --outlining                                   outline instructions
 ;; CHECK-NEXT:
 ;; CHECK-NEXT:   --pick-load-signs                             pick load signs based on their
@@ -319,9 +315,6 @@
 ;; CHECK-NEXT:   --print-minified                              print in minified s-expression
 ;; CHECK-NEXT:                                                 format
 ;; CHECK-NEXT:
-;; CHECK-NEXT:   --print-stack-ir                              print out Stack IR (useful for
-;; CHECK-NEXT:                                                 internal debugging)
-;; CHECK-NEXT:
 ;; CHECK-NEXT:   --propagate-debug-locs                        propagate debug location from
 ;; CHECK-NEXT:                                                 parents or previous siblings to
 ;; CHECK-NEXT:                                                 child nodes
@@ -696,6 +689,12 @@
 ;; CHECK-NEXT:                                                 in, but not inspect their
 ;; CHECK-NEXT:                                                 contents or call them.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --generate-stack-ir                           generate StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --optimize-stack-ir                           optimize StackIR during writing
+;; CHECK-NEXT:
+;; CHECK-NEXT:   --print-stack-ir                              print StackIR during writing
+;; CHECK-NEXT:
 ;; CHECK-NEXT:
 ;; CHECK-NEXT: General options:
 ;; CHECK-NEXT: ----------------
diff --git a/test/lit/passes/O.wast b/test/lit/passes/O.wast
index 7affbb8b7c9..baba79ee0c5 100644
--- a/test/lit/passes/O.wast
+++ b/test/lit/passes/O.wast
@@ -20,7 +20,7 @@
 
   ;; CHECK:      (export "end-if-else-call" (func $end-if-else-call))
 
-  ;; CHECK:      (func $ret (; has Stack IR ;) (result i32)
+  ;; CHECK:      (func $ret (result i32)
   ;; CHECK-NEXT:  (drop
   ;; CHECK-NEXT:   (call $ret)
   ;; CHECK-NEXT:  )
@@ -50,7 +50,7 @@
       (unreachable)
     )
   )
-  ;; CHECK:      (func $if-0-unreachable-to-none (; has Stack IR ;) (param $0 i64)
+  ;; CHECK:      (func $if-0-unreachable-to-none (param $0 i64)
   ;; CHECK-NEXT:  (unreachable)
   ;; CHECK-NEXT: )
   (func $if-0-unreachable-to-none (export "waka") (param $var$0 i64)
@@ -68,7 +68,7 @@
     )
    )
   )
-  ;; CHECK:      (func $many-selects (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $many-selects (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (select
   ;; CHECK-NEXT:   (i32.const -1073741824)
   ;; CHECK-NEXT:   (select
@@ -112,7 +112,7 @@
    )
    (local.get $0)
   )
-  ;; CHECK:      (func $end-if-else (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $end-if-else (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (select
   ;; CHECK-NEXT:   (i32.const 1)
   ;; CHECK-NEXT:   (local.get $0)
@@ -130,7 +130,7 @@
     )
     (local.get $x)
   )
-  ;; CHECK:      (func $end-if-else-call (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $end-if-else-call (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (if (result i32)
   ;; CHECK-NEXT:   (local.get $0)
   ;; CHECK-NEXT:   (then
diff --git a/test/lit/passes/O1_skip.wast b/test/lit/passes/O1_skip.wast
index 2cefecdcf98..54d6a684377 100644
--- a/test/lit/passes/O1_skip.wast
+++ b/test/lit/passes/O1_skip.wast
@@ -46,7 +46,7 @@
 )
 ;; CHECK:      (export "foo" (func $foo))
 
-;; CHECK:      (func $foo (; has Stack IR ;) (param $p i32)
+;; CHECK:      (func $foo (param $p i32)
 ;; CHECK-NEXT:  (local $x i32)
 ;; CHECK-NEXT:  (local $y i32)
 ;; CHECK-NEXT:  (call $log
diff --git a/test/lit/passes/O3_Oz.wast b/test/lit/passes/O3_Oz.wast
index 48345663e65..cc129c964ce 100644
--- a/test/lit/passes/O3_Oz.wast
+++ b/test/lit/passes/O3_Oz.wast
@@ -14,7 +14,7 @@
 
   ;; CHECK:      (export "export" (func $export))
 
-  ;; CHECK:      (func $export (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $export (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (i32.add
   ;; CHECK-NEXT:   (local.tee $0
   ;; CHECK-NEXT:    (i32.add
diff --git a/test/lit/passes/O3_inline-functions-with-loops_flexible-inline-max-function-size=30.wast b/test/lit/passes/O3_inline-functions-with-loops_flexible-inline-max-function-size=30.wast
index 7037baf7d2d..830008e2fc6 100644
--- a/test/lit/passes/O3_inline-functions-with-loops_flexible-inline-max-function-size=30.wast
+++ b/test/lit/passes/O3_inline-functions-with-loops_flexible-inline-max-function-size=30.wast
@@ -22,7 +22,7 @@
 
   ;; CHECK:      (export "memory" (memory $memory))
 
-  ;; CHECK:      (func $fib (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $fib (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (if
   ;; CHECK-NEXT:   (i32.le_s
   ;; CHECK-NEXT:    (local.get $0)
@@ -76,7 +76,7 @@
       )
     )
   )
-  ;; CHECK:      (func $looped (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $looped (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (loop $L0
   ;; CHECK-NEXT:   (if
   ;; CHECK-NEXT:    (i32.ge_s
@@ -123,7 +123,7 @@
     )
   )
 
-  ;; CHECK:      (func $t1 (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $t1 (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (local.set $0
   ;; CHECK-NEXT:   (i32.add
   ;; CHECK-NEXT:    (local.get $0)
@@ -157,7 +157,7 @@
       )
     )
   )
-  ;; CHECK:      (func $t2 (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $t2 (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (call $fib
   ;; CHECK-NEXT:   (local.get $0)
   ;; CHECK-NEXT:  )
@@ -168,7 +168,7 @@
     )
   )
 
-  ;; CHECK:      (func $t3 (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $t3 (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (call $fib
   ;; CHECK-NEXT:   (i32.add
   ;; CHECK-NEXT:    (local.get $0)
diff --git a/test/lit/passes/O4_disable-bulk-memory.wast b/test/lit/passes/O4_disable-bulk-memory.wast
index 0cafb1d5da5..d75258a9640 100644
--- a/test/lit/passes/O4_disable-bulk-memory.wast
+++ b/test/lit/passes/O4_disable-bulk-memory.wast
@@ -9,7 +9,7 @@
  (global $global$0 (mut i32) (i32.const 10))
  ;; CHECK:      (export "func_59_invoker" (func $0))
  (export "func_59_invoker" (func $0))
- ;; CHECK:      (func $0 (; has Stack IR ;)
+ ;; CHECK:      (func $0
  ;; CHECK-NEXT:  (unreachable)
  ;; CHECK-NEXT: )
  (func $0 (; 0 ;) (type $0)
@@ -226,7 +226,7 @@
   )
   (local.get $0)
  )
- ;; CHECK:      (func $~lib/allocator/arena/__memory_allocate (; has Stack IR ;) (param $0 i32) (result i32)
+ ;; CHECK:      (func $~lib/allocator/arena/__memory_allocate (param $0 i32) (result i32)
  ;; CHECK-NEXT:  (local $1 i32)
  ;; CHECK-NEXT:  (local $2 i32)
  ;; CHECK-NEXT:  (local $3 i32)
@@ -569,7 +569,7 @@
   )
   (local.get $0)
  )
- ;; CHECK:      (func $assembly/index/Body#constructor (; has Stack IR ;) (param $0 f64) (param $1 f64) (param $2 f64) (param $3 f64) (param $4 f64) (param $5 f64) (param $6 f64) (result i32)
+ ;; CHECK:      (func $assembly/index/Body#constructor (param $0 f64) (param $1 f64) (param $2 f64) (param $3 f64) (param $4 f64) (param $5 f64) (param $6 f64) (result i32)
  ;; CHECK-NEXT:  (local $7 i32)
  ;; CHECK-NEXT:  (f64.store
  ;; CHECK-NEXT:   (local.tee $7
@@ -1299,7 +1299,7 @@
    (local.get $5)
   )
  )
- ;; CHECK:      (func $assembly/index/init (; has Stack IR ;)
+ ;; CHECK:      (func $assembly/index/init
  ;; CHECK-NEXT:  (local $0 i32)
  ;; CHECK-NEXT:  (local $1 i32)
  ;; CHECK-NEXT:  (local $2 i32)
@@ -1873,7 +1873,7 @@
    )
   )
  )
- ;; CHECK:      (func $assembly/index/NBodySystem#advance (; has Stack IR ;) (param $0 i32)
+ ;; CHECK:      (func $assembly/index/NBodySystem#advance (param $0 i32)
  ;; CHECK-NEXT:  (local $1 i32)
  ;; CHECK-NEXT:  (local $2 f64)
  ;; CHECK-NEXT:  (local $3 i32)
@@ -2723,7 +2723,7 @@
   )
   (local.get $7)
  )
- ;; CHECK:      (func $assembly/index/step (; has Stack IR ;) (result f64)
+ ;; CHECK:      (func $assembly/index/step (result f64)
  ;; CHECK-NEXT:  (local $0 f64)
  ;; CHECK-NEXT:  (local $1 i32)
  ;; CHECK-NEXT:  (local $2 i32)
@@ -2933,7 +2933,7 @@
    (global.get $global$5)
   )
  )
- ;; CHECK:      (func $assembly/index/bench (; has Stack IR ;) (param $0 i32)
+ ;; CHECK:      (func $assembly/index/bench (param $0 i32)
  ;; CHECK-NEXT:  (local $1 i32)
  ;; CHECK-NEXT:  (block $label$1
  ;; CHECK-NEXT:   (loop $label$2
@@ -2985,7 +2985,7 @@
    )
   )
  )
- ;; CHECK:      (func $assembly/index/getBody (; has Stack IR ;) (param $0 i32) (result i32)
+ ;; CHECK:      (func $assembly/index/getBody (param $0 i32) (result i32)
  ;; CHECK-NEXT:  (local $1 i32)
  ;; CHECK-NEXT:  (if (result i32)
  ;; CHECK-NEXT:   (i32.lt_u
@@ -3065,7 +3065,7 @@
    )
   )
  )
- ;; CHECK:      (func $start (; has Stack IR ;)
+ ;; CHECK:      (func $start
  ;; CHECK-NEXT:  (global.set $global$0
  ;; CHECK-NEXT:   (i32.const 104)
  ;; CHECK-NEXT:  )
@@ -3076,7 +3076,7 @@
  (func $start (; 26 ;) (type $0)
   (call $start:assembly/index)
  )
- ;; CHECK:      (func $null (; has Stack IR ;)
+ ;; CHECK:      (func $null
  ;; CHECK-NEXT:  (nop)
  ;; CHECK-NEXT: )
  (func $null (; 27 ;) (type $0)
diff --git a/test/lit/passes/O_fast-math.wast b/test/lit/passes/O_fast-math.wast
index 722f44a05c4..a964edc993f 100644
--- a/test/lit/passes/O_fast-math.wast
+++ b/test/lit/passes/O_fast-math.wast
@@ -37,7 +37,7 @@
 
  ;; CHECK:      (export "abs_sub_zero2" (func $abs_sub_zero2))
 
- ;; CHECK:      (func $div (; has Stack IR ;) (result f32)
+ ;; CHECK:      (func $div (result f32)
  ;; CHECK-NEXT:  (f32.const -nan:0x23017a)
  ;; CHECK-NEXT: )
  (func $div (export "div") (result f32)
@@ -46,7 +46,7 @@
    (f32.const 1)
   )
  )
- ;; CHECK:      (func $mul1 (; has Stack IR ;) (result f32)
+ ;; CHECK:      (func $mul1 (result f32)
  ;; CHECK-NEXT:  (f32.const -nan:0x34546d)
  ;; CHECK-NEXT: )
  (func $mul1 (export "mul1") (result f32)
@@ -55,7 +55,7 @@
    (f32.const 1)
   )
  )
- ;; CHECK:      (func $mul2 (; has Stack IR ;) (result f32)
+ ;; CHECK:      (func $mul2 (result f32)
  ;; CHECK-NEXT:  (f32.const nan:0x400000)
  ;; CHECK-NEXT: )
  (func $mul2 (export "mul2") (result f32)
@@ -100,7 +100,7 @@
    (f32.const -0)
   )
  )
- ;; CHECK:      (func $mul_neg_one1 (; has Stack IR ;) (param $0 f32) (result f32)
+ ;; CHECK:      (func $mul_neg_one1 (param $0 f32) (result f32)
  ;; CHECK-NEXT:  (f32.neg
  ;; CHECK-NEXT:   (local.get $0)
  ;; CHECK-NEXT:  )
@@ -111,7 +111,7 @@
    (f32.const -1)
   )
  )
- ;; CHECK:      (func $mul_neg_one2 (; has Stack IR ;) (param $0 f64) (result f64)
+ ;; CHECK:      (func $mul_neg_one2 (param $0 f64) (result f64)
  ;; CHECK-NEXT:  (f64.neg
  ;; CHECK-NEXT:   (local.get $0)
  ;; CHECK-NEXT:  )
@@ -122,7 +122,7 @@
    (f64.const -1)
   )
  )
- ;; CHECK:      (func $abs_sub_zero1 (; has Stack IR ;) (param $0 f32) (result f32)
+ ;; CHECK:      (func $abs_sub_zero1 (param $0 f32) (result f32)
  ;; CHECK-NEXT:  (f32.abs
  ;; CHECK-NEXT:   (local.get $0)
  ;; CHECK-NEXT:  )
@@ -136,7 +136,7 @@
    )
   )
  )
- ;; CHECK:      (func $abs_sub_zero2 (; has Stack IR ;) (param $0 f64) (result f64)
+ ;; CHECK:      (func $abs_sub_zero2 (param $0 f64) (result f64)
  ;; CHECK-NEXT:  (f64.abs
  ;; CHECK-NEXT:   (local.get $0)
  ;; CHECK-NEXT:  )
diff --git a/test/lit/passes/Oz.wast b/test/lit/passes/Oz.wast
index 8c1db3083b7..eab5a95afd6 100644
--- a/test/lit/passes/Oz.wast
+++ b/test/lit/passes/Oz.wast
@@ -37,7 +37,7 @@
 
   ;; CHECK:      (export "precompute-simd" (func $precompute-simd))
 
-  ;; CHECK:      (func $basics (type $0) (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+  ;; CHECK:      (func $basics (type $0) (param $0 i32) (param $1 i32) (result i32)
   ;; CHECK-NEXT:  (i32.add
   ;; CHECK-NEXT:   (local.tee $0
   ;; CHECK-NEXT:    (i32.add
@@ -59,7 +59,7 @@
     )
     (i32.add (local.get $x2) (local.get $y2))
   )
-  ;; CHECK:      (func $8 (type $2) (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (result i32)
+  ;; CHECK:      (func $8 (type $2) (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (result i32)
   ;; CHECK-NEXT:  (i32.store
   ;; CHECK-NEXT:   (local.tee $0
   ;; CHECK-NEXT:    (i32.add
@@ -131,7 +131,7 @@
     )
   )
 
-  ;; CHECK:      (func $9 (type $1) (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $9 (type $1) (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (i32.mul
   ;; CHECK-NEXT:   (local.get $0)
   ;; CHECK-NEXT:   (i32.const -4)
@@ -147,7 +147,7 @@
     )
   )
 
-  ;; CHECK:      (func $10 (type $1) (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $10 (type $1) (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (i32.shl
   ;; CHECK-NEXT:   (local.get $0)
   ;; CHECK-NEXT:   (i32.const 31)
@@ -163,7 +163,7 @@
     )
   )
 
-  ;; CHECK:      (func $11 (type $1) (; has Stack IR ;) (param $0 i32) (result i32)
+  ;; CHECK:      (func $11 (type $1) (param $0 i32) (result i32)
   ;; CHECK-NEXT:  (if
   ;; CHECK-NEXT:   (local.get $0)
   ;; CHECK-NEXT:   (then
@@ -201,7 +201,7 @@
     )
     (i32.const 0)
   )
-  ;; CHECK:      (func $12 (type $0) (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+  ;; CHECK:      (func $12 (type $0) (param $0 i32) (param $1 i32) (result i32)
   ;; CHECK-NEXT:  (if
   ;; CHECK-NEXT:   (local.get $0)
   ;; CHECK-NEXT:   (then
@@ -239,7 +239,7 @@
     )
     (i32.const 0)
   )
-  ;; CHECK:      (func $13 (type $0) (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+  ;; CHECK:      (func $13 (type $0) (param $0 i32) (param $1 i32) (result i32)
   ;; CHECK-NEXT:  (if
   ;; CHECK-NEXT:   (select
   ;; CHECK-NEXT:    (local.get $1)
@@ -268,7 +268,7 @@
     (i32.const 0)
   )
 
-  ;; CHECK:      (func $14 (type $0) (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+  ;; CHECK:      (func $14 (type $0) (param $0 i32) (param $1 i32) (result i32)
   ;; CHECK-NEXT:  (if
   ;; CHECK-NEXT:   (select
   ;; CHECK-NEXT:    (i32.const 0)
@@ -297,7 +297,7 @@
     (i32.const 0)
   )
 
-  ;; CHECK:      (func $precompute-simd (type $3) (; has Stack IR ;) (result v128)
+  ;; CHECK:      (func $precompute-simd (type $3) (result v128)
   ;; CHECK-NEXT:  (v128.const i32x4 0x00000000 0x00000000 0x00000000 0x00000000)
   ;; CHECK-NEXT: )
   (func $precompute-simd (export "precompute-simd") (result v128)
diff --git a/test/lit/passes/asyncify_mod-asyncify-always-and-only-unwind_O.wast b/test/lit/passes/asyncify_mod-asyncify-always-and-only-unwind_O.wast
index 99ac2c05f66..ec31a4118e7 100644
--- a/test/lit/passes/asyncify_mod-asyncify-always-and-only-unwind_O.wast
+++ b/test/lit/passes/asyncify_mod-asyncify-always-and-only-unwind_O.wast
@@ -42,7 +42,7 @@
 
   ;; CHECK:      (export "asyncify_get_state" (func $asyncify_get_state))
 
-  ;; CHECK:      (func $calls-import (; has Stack IR ;)
+  ;; CHECK:      (func $calls-import
   ;; CHECK-NEXT:  (local $0 i32)
   ;; CHECK-NEXT:  (call $import)
   ;; CHECK-NEXT:  (i32.store
@@ -76,7 +76,7 @@
     (drop (i32.eqz (i32.const 17)))
   )
 )
-;; CHECK:      (func $asyncify_start_unwind (; has Stack IR ;) (param $0 i32)
+;; CHECK:      (func $asyncify_start_unwind (param $0 i32)
 ;; CHECK-NEXT:  (global.set $__asyncify_state
 ;; CHECK-NEXT:   (i32.const 1)
 ;; CHECK-NEXT:  )
@@ -98,7 +98,7 @@
 ;; CHECK-NEXT:  )
 ;; CHECK-NEXT: )
 
-;; CHECK:      (func $asyncify_stop_unwind (; has Stack IR ;)
+;; CHECK:      (func $asyncify_stop_unwind
 ;; CHECK-NEXT:  (global.set $__asyncify_state
 ;; CHECK-NEXT:   (i32.const 0)
 ;; CHECK-NEXT:  )
@@ -117,7 +117,7 @@
 ;; CHECK-NEXT:  )
 ;; CHECK-NEXT: )
 
-;; CHECK:      (func $asyncify_start_rewind (; has Stack IR ;) (param $0 i32)
+;; CHECK:      (func $asyncify_start_rewind (param $0 i32)
 ;; CHECK-NEXT:  (global.set $__asyncify_state
 ;; CHECK-NEXT:   (i32.const 2)
 ;; CHECK-NEXT:  )
@@ -139,6 +139,6 @@
 ;; CHECK-NEXT:  )
 ;; CHECK-NEXT: )
 
-;; CHECK:      (func $asyncify_get_state (; has Stack IR ;) (result i32)
+;; CHECK:      (func $asyncify_get_state (result i32)
 ;; CHECK-NEXT:  (global.get $__asyncify_state)
 ;; CHECK-NEXT: )
diff --git a/test/lit/passes/asyncify_mod-asyncify-never-unwind_O.wast b/test/lit/passes/asyncify_mod-asyncify-never-unwind_O.wast
index 38a54ea80e3..eefdabe3438 100644
--- a/test/lit/passes/asyncify_mod-asyncify-never-unwind_O.wast
+++ b/test/lit/passes/asyncify_mod-asyncify-never-unwind_O.wast
@@ -41,7 +41,7 @@
 
   ;; CHECK:      (export "asyncify_get_state" (func $asyncify_get_state))
 
-  ;; CHECK:      (func $calls-import (; has Stack IR ;)
+  ;; CHECK:      (func $calls-import
   ;; CHECK-NEXT:  (if
   ;; CHECK-NEXT:   (i32.or
   ;; CHECK-NEXT:    (i32.eqz
@@ -95,7 +95,7 @@
     (drop (i32.eqz (i32.const 17)))
   )
 )
-;; CHECK:      (func $asyncify_start_unwind (; has Stack IR ;) (param $0 i32)
+;; CHECK:      (func $asyncify_start_unwind (param $0 i32)
 ;; CHECK-NEXT:  (global.set $__asyncify_state
 ;; CHECK-NEXT:   (i32.const 1)
 ;; CHECK-NEXT:  )
@@ -117,7 +117,7 @@
 ;; CHECK-NEXT:  )
 ;; CHECK-NEXT: )
 
-;; CHECK:      (func $asyncify_stop_unwind (; has Stack IR ;)
+;; CHECK:      (func $asyncify_stop_unwind
 ;; CHECK-NEXT:  (global.set $__asyncify_state
 ;; CHECK-NEXT:   (i32.const 0)
 ;; CHECK-NEXT:  )
@@ -136,7 +136,7 @@
 ;; CHECK-NEXT:  )
 ;; CHECK-NEXT: )
 
-;; CHECK:      (func $asyncify_start_rewind (; has Stack IR ;) (param $0 i32)
+;; CHECK:      (func $asyncify_start_rewind (param $0 i32)
 ;; CHECK-NEXT:  (global.set $__asyncify_state
 ;; CHECK-NEXT:   (i32.const 2)
 ;; CHECK-NEXT:  )
@@ -158,6 +158,6 @@
 ;; CHECK-NEXT:  )
 ;; CHECK-NEXT: )
 
-;; CHECK:      (func $asyncify_get_state (; has Stack IR ;) (result i32)
+;; CHECK:      (func $asyncify_get_state (result i32)
 ;; CHECK-NEXT:  (global.get $__asyncify_state)
 ;; CHECK-NEXT: )
diff --git a/test/lit/passes/flatten_dfo_O3_enable-threads.wast b/test/lit/passes/flatten_dfo_O3_enable-threads.wast
index 34142b73f58..3e2dfb5395b 100644
--- a/test/lit/passes/flatten_dfo_O3_enable-threads.wast
+++ b/test/lit/passes/flatten_dfo_O3_enable-threads.wast
@@ -28,7 +28,7 @@
 
  ;; CHECK:      (export "dfo-tee-get" (func $dfo-tee-get))
 
- ;; CHECK:      (func $one (; has Stack IR ;)
+ ;; CHECK:      (func $one
  ;; CHECK-NEXT:  (block $label$3
  ;; CHECK-NEXT:   (br_if $label$3
  ;; CHECK-NEXT:    (i32.load
@@ -56,7 +56,7 @@
   )
   (unreachable)
  )
- ;; CHECK:      (func $two (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+ ;; CHECK:      (func $two (param $0 i32) (param $1 i32) (result i32)
  ;; CHECK-NEXT:  (i32.const 0)
  ;; CHECK-NEXT: )
  (func $two (export "two") (param $var$0 i32) (param $var$1 i32) (result i32)
@@ -110,7 +110,7 @@
   (nop)
   (i32.const 0)
  )
- ;; CHECK:      (func $use-var (; has Stack IR ;) (param $0 i64) (param $1 i32) (result f64)
+ ;; CHECK:      (func $use-var (param $0 i64) (param $1 i32) (result f64)
  ;; CHECK-NEXT:  (loop $label$8
  ;; CHECK-NEXT:   (br_if $label$8
  ;; CHECK-NEXT:    (local.get $1)
@@ -184,7 +184,7 @@
   )
   (unreachable)
  )
- ;; CHECK:      (func $bad1 (; has Stack IR ;)
+ ;; CHECK:      (func $bad1
  ;; CHECK-NEXT:  (i32.store
  ;; CHECK-NEXT:   (i32.const 1)
  ;; CHECK-NEXT:   (i32.const -16384)
@@ -236,7 +236,7 @@
    )
   )
  )
- ;; CHECK:      (func $only-dfo (; has Stack IR ;) (param $0 f64) (result f64)
+ ;; CHECK:      (func $only-dfo (param $0 f64) (result f64)
  ;; CHECK-NEXT:  (local $1 i32)
  ;; CHECK-NEXT:  (loop $label$1
  ;; CHECK-NEXT:   (br $label$1)
@@ -270,7 +270,7 @@
    (br $label$1)
   )
  )
- ;; CHECK:      (func $dfo-tee-get (; has Stack IR ;) (result i32)
+ ;; CHECK:      (func $dfo-tee-get (result i32)
  ;; CHECK-NEXT:  (i32.const 1)
  ;; CHECK-NEXT: )
  (func $dfo-tee-get (export "dfo-tee-get") (result i32)
diff --git a/test/lit/passes/flatten_simplify-locals-nonesting_dfo_O3.wast b/test/lit/passes/flatten_simplify-locals-nonesting_dfo_O3.wast
index 142fabeea14..2c033e0fe2c 100644
--- a/test/lit/passes/flatten_simplify-locals-nonesting_dfo_O3.wast
+++ b/test/lit/passes/flatten_simplify-locals-nonesting_dfo_O3.wast
@@ -25,7 +25,7 @@
 
  ;; CHECK:      (export "only-dfo" (func $only-dfo))
 
- ;; CHECK:      (func $if-select (; has Stack IR ;)
+ ;; CHECK:      (func $if-select
  ;; CHECK-NEXT:  (nop)
  ;; CHECK-NEXT: )
  (func $if-select (export "if-select")
@@ -47,7 +47,7 @@
    )
   )
  )
- ;; CHECK:      (func $unreachable-body-update-zext (; has Stack IR ;) (result f64)
+ ;; CHECK:      (func $unreachable-body-update-zext (result f64)
  ;; CHECK-NEXT:  (unreachable)
  ;; CHECK-NEXT: )
  (func $unreachable-body-update-zext (export "unreachable-body-update-zext") (result f64)
@@ -61,7 +61,7 @@
   )
   (f64.const -9223372036854775808)
  )
- ;; CHECK:      (func $ssa-const (; has Stack IR ;) (param $0 i32) (param $1 f64) (param $2 f64) (result i32)
+ ;; CHECK:      (func $ssa-const (param $0 i32) (param $1 f64) (param $2 f64) (result i32)
  ;; CHECK-NEXT:  (unreachable)
  ;; CHECK-NEXT: )
  (func $ssa-const (export "ssa-const") (param $var$0 i32) (param $var$1 f64) (param $var$2 f64) (result i32)
@@ -99,7 +99,7 @@
    )
   )
  )
- ;; CHECK:      (func $if-nothing (; has Stack IR ;) (param $0 i64)
+ ;; CHECK:      (func $if-nothing (param $0 i64)
  ;; CHECK-NEXT:  (unreachable)
  ;; CHECK-NEXT: )
  (func $if-nothing (export "if-nothing") (param $var$0 i64)
@@ -130,7 +130,7 @@
    (unreachable)
   )
  )
- ;; CHECK:      (func $only-dfo (; has Stack IR ;) (param $0 f64) (result i32)
+ ;; CHECK:      (func $only-dfo (param $0 f64) (result i32)
  ;; CHECK-NEXT:  (local $1 i32)
  ;; CHECK-NEXT:  (loop $label$1
  ;; CHECK-NEXT:   (if
diff --git a/test/lit/passes/global-effects-O.wast b/test/lit/passes/global-effects-O.wast
index c24159eace4..c7ba0678186 100644
--- a/test/lit/passes/global-effects-O.wast
+++ b/test/lit/passes/global-effects-O.wast
@@ -56,13 +56,13 @@
   ;; CHECK_1:      (func $main (type $0)
   ;; CHECK_1-NEXT:  (nop)
   ;; CHECK_1-NEXT: )
-  ;; CHECK_3:      (func $main (type $0) (; has Stack IR ;)
+  ;; CHECK_3:      (func $main (type $0)
   ;; CHECK_3-NEXT:  (nop)
   ;; CHECK_3-NEXT: )
-  ;; CHECK_s:      (func $main (type $0) (; has Stack IR ;)
+  ;; CHECK_s:      (func $main (type $0)
   ;; CHECK_s-NEXT:  (nop)
   ;; CHECK_s-NEXT: )
-  ;; CHECK_O:      (func $main (type $0) (; has Stack IR ;)
+  ;; CHECK_O:      (func $main (type $0)
   ;; CHECK_O-NEXT:  (nop)
   ;; CHECK_O-NEXT: )
   (func $main
@@ -119,7 +119,7 @@
   ;; CHECK_1-NEXT:   (local.get $0)
   ;; CHECK_1-NEXT:  )
   ;; CHECK_1-NEXT: )
-  ;; CHECK_3:      (func $pointless-work (type $1) (; has Stack IR ;) (result i32)
+  ;; CHECK_3:      (func $pointless-work (type $1) (result i32)
   ;; CHECK_3-NEXT:  (local $0 i32)
   ;; CHECK_3-NEXT:  (loop $loop (result i32)
   ;; CHECK_3-NEXT:   (br_if $loop
@@ -136,7 +136,7 @@
   ;; CHECK_3-NEXT:   (local.get $0)
   ;; CHECK_3-NEXT:  )
   ;; CHECK_3-NEXT: )
-  ;; CHECK_s:      (func $pointless-work (type $1) (; has Stack IR ;) (result i32)
+  ;; CHECK_s:      (func $pointless-work (type $1) (result i32)
   ;; CHECK_s-NEXT:  (local $0 i32)
   ;; CHECK_s-NEXT:  (loop $loop (result i32)
   ;; CHECK_s-NEXT:   (br_if $loop
@@ -153,7 +153,7 @@
   ;; CHECK_s-NEXT:   (local.get $0)
   ;; CHECK_s-NEXT:  )
   ;; CHECK_s-NEXT: )
-  ;; CHECK_O:      (func $pointless-work (type $1) (; has Stack IR ;) (result i32)
+  ;; CHECK_O:      (func $pointless-work (type $1) (result i32)
   ;; CHECK_O-NEXT:  (local $0 i32)
   ;; CHECK_O-NEXT:  (loop $loop (result i32)
   ;; CHECK_O-NEXT:   (br_if $loop
diff --git a/test/lit/passes/gto_and_cfp_in_O.wast b/test/lit/passes/gto_and_cfp_in_O.wast
index a723038eb2f..b1e9a47df50 100644
--- a/test/lit/passes/gto_and_cfp_in_O.wast
+++ b/test/lit/passes/gto_and_cfp_in_O.wast
@@ -26,7 +26,7 @@
 
   ;; OPEN_WORLD:      (export "main" (func $main))
 
-  ;; OPEN_WORLD:      (func $by-ref (type $1) (; has Stack IR ;)
+  ;; OPEN_WORLD:      (func $by-ref (type $1)
   ;; OPEN_WORLD-NEXT:  (struct.set $struct 1
   ;; OPEN_WORLD-NEXT:   (global.get $glob)
   ;; OPEN_WORLD-NEXT:   (i32.const 200)
@@ -49,10 +49,10 @@
 
   ;; CHECK:      (export "main" (func $main))
 
-  ;; CHECK:      (func $main (type $0) (; has Stack IR ;) (result i32)
+  ;; CHECK:      (func $main (type $0) (result i32)
   ;; CHECK-NEXT:  (i32.const 100)
   ;; CHECK-NEXT: )
-  ;; OPEN_WORLD:      (func $main (type $2) (; has Stack IR ;) (result i32)
+  ;; OPEN_WORLD:      (func $main (type $2) (result i32)
   ;; OPEN_WORLD-NEXT:  (struct.get $struct 1
   ;; OPEN_WORLD-NEXT:   (global.get $glob)
   ;; OPEN_WORLD-NEXT:  )
diff --git a/test/lit/passes/type-ssa_and_merging.wast b/test/lit/passes/type-ssa_and_merging.wast
index 670de31ac45..8928820bfcd 100644
--- a/test/lit/passes/type-ssa_and_merging.wast
+++ b/test/lit/passes/type-ssa_and_merging.wast
@@ -33,7 +33,7 @@
 
   ;; NOP:      (export "main2" (func $main2))
 
-  ;; NOP:      (func $main1 (type $2) (; has Stack IR ;) (result i32)
+  ;; NOP:      (func $main1 (type $2) (result i32)
   ;; NOP-NEXT:  (call $get-a-1
   ;; NOP-NEXT:   (struct.new $A
   ;; NOP-NEXT:    (i32.const 42)
@@ -57,7 +57,7 @@
     )
   )
 
-  ;; NOP:      (func $main2 (type $2) (; has Stack IR ;) (result i32)
+  ;; NOP:      (func $main2 (type $2) (result i32)
   ;; NOP-NEXT:  (call $get-a-2
   ;; NOP-NEXT:   (struct.new $A
   ;; NOP-NEXT:    (i32.const 1337)
@@ -77,7 +77,7 @@
     )
   )
 
-  ;; NOP:      (func $get-a-1 (type $0) (; has Stack IR ;) (param $0 (ref $A)) (result i32)
+  ;; NOP:      (func $get-a-1 (type $0) (param $0 (ref $A)) (result i32)
   ;; NOP-NEXT:  (if
   ;; NOP-NEXT:   (call $import)
   ;; NOP-NEXT:   (then
@@ -119,7 +119,7 @@
     (struct.get $A 0 (local.get 0))
   )
 
-  ;; NOP:      (func $get-a-2 (type $0) (; has Stack IR ;) (param $0 (ref $A)) (result i32)
+  ;; NOP:      (func $get-a-2 (type $0) (param $0 (ref $A)) (result i32)
   ;; NOP-NEXT:  (if
   ;; NOP-NEXT:   (call $import)
   ;; NOP-NEXT:   (then
diff --git a/test/passes/O.bin.txt b/test/passes/O.bin.txt
index d35a4d11c64..3302ebcc710 100644
--- a/test/passes/O.bin.txt
+++ b/test/passes/O.bin.txt
@@ -5,7 +5,7 @@
  (export "fac-iter" (func $2))
  (export "fac-iter-named" (func $3))
  (export "fac-opt" (func $4))
- (func $0 (; has Stack IR ;) (param $0 i64) (result i64)
+ (func $0 (param $0 i64) (result i64)
   (if (result i64)
    (i64.eqz
     (local.get $0)
@@ -26,7 +26,7 @@
    )
   )
  )
- (func $1 (; has Stack IR ;) (param $0 i64) (result i64)
+ (func $1 (param $0 i64) (result i64)
   (if (result i64)
    (i64.eqz
     (local.get $0)
@@ -47,10 +47,10 @@
    )
   )
  )
- (func $2 (; has Stack IR ;) (param $0 i64) (result i64)
+ (func $2 (param $0 i64) (result i64)
   (unreachable)
  )
- (func $3 (; has Stack IR ;) (param $0 i64) (result i64)
+ (func $3 (param $0 i64) (result i64)
   (local $1 i64)
   (local.set $1
    (i64.const 1)
@@ -81,7 +81,7 @@
   )
   (local.get $1)
  )
- (func $4 (; has Stack IR ;) (param $0 i64) (result i64)
+ (func $4 (param $0 i64) (result i64)
   (local $1 i64)
   (local.set $1
    (i64.const 1)
diff --git a/test/passes/O1_print-stack-ir.txt b/test/passes/O1_print-stack-ir.txt
index 0a64713d378..d6cececfca8 100644
--- a/test/passes/O1_print-stack-ir.txt
+++ b/test/passes/O1_print-stack-ir.txt
@@ -28,25 +28,16 @@
  (type $0 (func (param i32) (result i32)))
  (export "stacky-help" (func $stacky-help))
  (func $stacky-help (param $0 i32) (result i32)
-  (i32.add
-   (call $stacky-help
-    (i32.const 0)
-   )
-   (block (result i32)
-    (local.set $0
-     (call $stacky-help
-      (i32.const 1)
-     )
-    )
-    (drop
-     (call $stacky-help
-      (i32.const 2)
-     )
-    )
-    (i32.eqz
-     (local.get $0)
-    )
-   )
-  )
+  i32.const 0
+  call $stacky-help
+  i32.const 1
+  call $stacky-help
+  local.set $0
+  i32.const 2
+  call $stacky-help
+  drop
+  local.get $0
+  i32.eqz
+  i32.add
  )
 )
diff --git a/test/passes/O2_precompute-propagate_print-stack-ir.txt b/test/passes/O2_precompute-propagate_print-stack-ir.txt
index b0789141a81..119d1cafb71 100644
--- a/test/passes/O2_precompute-propagate_print-stack-ir.txt
+++ b/test/passes/O2_precompute-propagate_print-stack-ir.txt
@@ -15,10 +15,8 @@
  (export "func" (func $func))
  (func $func (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i64) (result i64)
   (local $4 i32)
-  (local.set $3
-   (i64.const 2147483647)
-  )
-  (nop)
-  (i64.const 2147483647)
+  i64.const 2147483647
+  local.set $3
+  i64.const 2147483647
  )
 )
diff --git a/test/passes/O2_print-stack-ir.txt b/test/passes/O2_print-stack-ir.txt
index cdfccc3d467..d6cececfca8 100644
--- a/test/passes/O2_print-stack-ir.txt
+++ b/test/passes/O2_print-stack-ir.txt
@@ -2,23 +2,6 @@
  (type $0 (func (param i32) (result i32)))
  (export "stacky-help" (func $stacky-help))
  (func $stacky-help (param $0 i32) (result i32)
-  i32.const 0
-  call $stacky-help
-  i32.const 1
-  call $stacky-help
-  local.set $0
-  i32.const 2
-  call $stacky-help
-  drop
-  local.get $0
-  i32.eqz
-  i32.add
- )
-)
-(module
- (type $0 (func (param i32) (result i32)))
- (export "stacky-help" (func $stacky-help))
- (func $stacky-help (; has Stack IR ;) (param $0 i32) (result i32)
   (i32.add
    (call $stacky-help
     (i32.const 0)
@@ -41,3 +24,20 @@
   )
  )
 )
+(module
+ (type $0 (func (param i32) (result i32)))
+ (export "stacky-help" (func $stacky-help))
+ (func $stacky-help (param $0 i32) (result i32)
+  i32.const 0
+  call $stacky-help
+  i32.const 1
+  call $stacky-help
+  local.set $0
+  i32.const 2
+  call $stacky-help
+  drop
+  local.get $0
+  i32.eqz
+  i32.add
+ )
+)
diff --git a/test/passes/O3_low-memory-unused_metrics.txt b/test/passes/O3_low-memory-unused_metrics.txt
index 547eb1673ed..fd9245adc2a 100644
--- a/test/passes/O3_low-memory-unused_metrics.txt
+++ b/test/passes/O3_low-memory-unused_metrics.txt
@@ -42,7 +42,7 @@ total
  (import "env" "memset" (func $fimport$97 (param i32 i32 i32) (result i32)))
  (import "env" "memcpy" (func $fimport$98 (param i32 i32 i32) (result i32)))
  (export "deflate" (func $0))
- (func $0 (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+ (func $0 (param $0 i32) (param $1 i32) (result i32)
   (local $2 i32)
   (local $3 i32)
   (local $4 i32)
diff --git a/test/passes/O3_print-stack-ir.txt b/test/passes/O3_print-stack-ir.txt
index 569c49966ea..18aa4053fd9 100644
--- a/test/passes/O3_print-stack-ir.txt
+++ b/test/passes/O3_print-stack-ir.txt
@@ -2,21 +2,6 @@
  (type $0 (func (param i32) (result i32)))
  (export "stacky-help" (func $stacky-help))
  (func $stacky-help (param $0 i32) (result i32)
-  i32.const 0
-  call $stacky-help
-  i32.const 1
-  call $stacky-help
-  i32.const 2
-  call $stacky-help
-  drop
-  i32.eqz
-  i32.add
- )
-)
-(module
- (type $0 (func (param i32) (result i32)))
- (export "stacky-help" (func $stacky-help))
- (func $stacky-help (; has Stack IR ;) (param $0 i32) (result i32)
   (i32.add
    (call $stacky-help
     (i32.const 0)
@@ -39,3 +24,18 @@
   )
  )
 )
+(module
+ (type $0 (func (param i32) (result i32)))
+ (export "stacky-help" (func $stacky-help))
+ (func $stacky-help (param $0 i32) (result i32)
+  i32.const 0
+  call $stacky-help
+  i32.const 1
+  call $stacky-help
+  i32.const 2
+  call $stacky-help
+  drop
+  i32.eqz
+  i32.add
+ )
+)
diff --git a/test/passes/Os_print-stack-ir_all-features_disable-gc.txt b/test/passes/Os_print-stack-ir_all-features_disable-gc.txt
index 569c49966ea..18aa4053fd9 100644
--- a/test/passes/Os_print-stack-ir_all-features_disable-gc.txt
+++ b/test/passes/Os_print-stack-ir_all-features_disable-gc.txt
@@ -2,21 +2,6 @@
  (type $0 (func (param i32) (result i32)))
  (export "stacky-help" (func $stacky-help))
  (func $stacky-help (param $0 i32) (result i32)
-  i32.const 0
-  call $stacky-help
-  i32.const 1
-  call $stacky-help
-  i32.const 2
-  call $stacky-help
-  drop
-  i32.eqz
-  i32.add
- )
-)
-(module
- (type $0 (func (param i32) (result i32)))
- (export "stacky-help" (func $stacky-help))
- (func $stacky-help (; has Stack IR ;) (param $0 i32) (result i32)
   (i32.add
    (call $stacky-help
     (i32.const 0)
@@ -39,3 +24,18 @@
   )
  )
 )
+(module
+ (type $0 (func (param i32) (result i32)))
+ (export "stacky-help" (func $stacky-help))
+ (func $stacky-help (param $0 i32) (result i32)
+  i32.const 0
+  call $stacky-help
+  i32.const 1
+  call $stacky-help
+  i32.const 2
+  call $stacky-help
+  drop
+  i32.eqz
+  i32.add
+ )
+)
diff --git a/test/passes/Oz_fuzz-exec_all-features.txt b/test/passes/Oz_fuzz-exec_all-features.txt
index c46085be11c..b69b9728cca 100644
--- a/test/passes/Oz_fuzz-exec_all-features.txt
+++ b/test/passes/Oz_fuzz-exec_all-features.txt
@@ -81,7 +81,7 @@
  (export "static-casts" (func $static-casts))
  (export "static-br_on_cast" (func $br_on_cast))
  (export "static-br_on_cast_fail" (func $static-br_on_cast_fail))
- (func $structs (type $void_func) (; has Stack IR ;)
+ (func $structs (type $void_func)
   (local $0 i32)
   (call $log
    (i32.const 0)
@@ -98,7 +98,7 @@
    (i32.const 100)
   )
  )
- (func $arrays (type $void_func) (; has Stack IR ;)
+ (func $arrays (type $void_func)
   (local $0 (ref $bytes))
   (local.set $0
    (array.new $bytes
@@ -139,12 +139,12 @@
    )
   )
  )
- (func $br_on_cast (type $void_func) (; has Stack IR ;)
+ (func $br_on_cast (type $void_func)
   (call $log
    (i32.const 3)
   )
  )
- (func $br_on_failed_cast-1 (type $void_func) (; has Stack IR ;)
+ (func $br_on_failed_cast-1 (type $void_func)
   (local $0 (ref $struct))
   (local.set $0
    (struct.new_default $struct)
@@ -166,7 +166,7 @@
    )
   )
  )
- (func $br_on_failed_cast-2 (type $void_func) (; has Stack IR ;)
+ (func $br_on_failed_cast-2 (type $void_func)
   (call $log
    (i32.const 1)
   )
@@ -174,15 +174,15 @@
    (i32.const 999)
   )
  )
- (func $cast-null-anyref-to-gc (type $void_func) (; has Stack IR ;)
+ (func $cast-null-anyref-to-gc (type $void_func)
   (call $log
    (i32.const 0)
   )
  )
- (func $br-on_non_null (type $void_func) (; has Stack IR ;)
+ (func $br-on_non_null (type $void_func)
   (nop)
  )
- (func $br-on_non_null-2 (type $void_func) (; has Stack IR ;)
+ (func $br-on_non_null-2 (type $void_func)
   (drop
    (block
     (call $log
@@ -192,7 +192,7 @@
    )
   )
  )
- (func $cast-on-func (type $void_func) (; has Stack IR ;)
+ (func $cast-on-func (type $void_func)
   (call $log
    (i32.const 0)
   )
@@ -204,7 +204,7 @@
   )
   (unreachable)
  )
- (func $init-array-packed (type $int_func) (; has Stack IR ;) (result i32)
+ (func $init-array-packed (type $int_func) (result i32)
   (array.get_u $bytes
    (array.new $bytes
     (i32.const -43)
@@ -213,7 +213,7 @@
    (i32.const 10)
   )
  )
- (func $array-copy (type $void_func) (; has Stack IR ;)
+ (func $array-copy (type $void_func)
   (local $0 (ref $bytes))
   (local $1 (ref $bytes))
   (array.set $bytes
@@ -268,7 +268,7 @@
    )
   )
  )
- (func $array.new_fixed (type $void_func) (; has Stack IR ;)
+ (func $array.new_fixed (type $void_func)
   (local $0 i32)
   (local $1 i32)
   (local.set $0
@@ -287,12 +287,12 @@
    (i32.const 50)
   )
  )
- (func $array.new_fixed-packed (type $void_func) (; has Stack IR ;)
+ (func $array.new_fixed-packed (type $void_func)
   (call $log
    (i32.const 8)
   )
  )
- (func $static-casts (type $void_func) (; has Stack IR ;)
+ (func $static-casts (type $void_func)
   (call $log
    (i32.const 1)
   )
@@ -312,7 +312,7 @@
    (i32.const 1)
   )
  )
- (func $static-br_on_cast_fail (type $void_func) (; has Stack IR ;)
+ (func $static-br_on_cast_fail (type $void_func)
   (call $log
    (i32.const -2)
   )
@@ -380,7 +380,7 @@ ignoring comparison of ExecutionResults!
 (module
  (type $0 (func (result i32)))
  (export "foo" (func $foo))
- (func $foo (type $0) (; has Stack IR ;) (result i32)
+ (func $foo (type $0) (result i32)
   (i32.const 0)
  )
 )
diff --git a/test/passes/converge_O3_metrics.bin.txt b/test/passes/converge_O3_metrics.bin.txt
index bd977b342de..312e67fe794 100644
--- a/test/passes/converge_O3_metrics.bin.txt
+++ b/test/passes/converge_O3_metrics.bin.txt
@@ -46,13 +46,13 @@ total
  (elem $0 (i32.const 0) $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $___stdout_write $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $__ZNSt3__211__stdoutbufIcE6xsputnEPKci $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $__ZNSt3__211__stdoutbufIcE8overflowEi)
  (export "_main" (func $_main))
  (export "_malloc" (func $_malloc))
- (func $b0 (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (param $4 i32) (param $5 i32) (param $6 i32) (result i32)
+ (func $b0 (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (param $4 i32) (param $5 i32) (param $6 i32) (result i32)
   (i32.const 0)
  )
- (func $_malloc (; has Stack IR ;) (param $0 i32) (result i32)
+ (func $_malloc (param $0 i32) (result i32)
   (i32.const 0)
  )
- (func $_main (; has Stack IR ;) (result i32)
+ (func $_main (result i32)
   (local $0 i32)
   (local $1 i32)
   (local.set $0
@@ -157,7 +157,7 @@ total
   )
   (i32.const 0)
  )
- (func $___stdout_write (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+ (func $___stdout_write (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
   (global.set $global$0
    (i32.const 32)
   )
@@ -187,7 +187,7 @@ total
   )
   (i32.const 1)
  )
- (func $__ZNSt3__211__stdoutbufIcE8overflowEi (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+ (func $__ZNSt3__211__stdoutbufIcE8overflowEi (param $0 i32) (param $1 i32) (result i32)
   (i32.store8
    (i32.const 0)
    (local.get $1)
@@ -212,7 +212,7 @@ total
   )
   (i32.const 0)
  )
- (func $__ZNSt3__211__stdoutbufIcE6xsputnEPKci (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+ (func $__ZNSt3__211__stdoutbufIcE6xsputnEPKci (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
   (drop
    (call_indirect (type $0)
     (i32.const 0)
@@ -277,13 +277,13 @@ total
  (elem $0 (i32.const 0) $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $___stdout_write $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $__ZNSt3__211__stdoutbufIcE6xsputnEPKci $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $__ZNSt3__211__stdoutbufIcE8overflowEi)
  (export "_main" (func $_main))
  (export "_malloc" (func $_malloc))
- (func $b0 (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (param $4 i32) (param $5 i32) (param $6 i32) (result i32)
+ (func $b0 (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (param $4 i32) (param $5 i32) (param $6 i32) (result i32)
   (i32.const 0)
  )
- (func $_malloc (; has Stack IR ;) (param $0 i32) (result i32)
+ (func $_malloc (param $0 i32) (result i32)
   (i32.const 0)
  )
- (func $_main (; has Stack IR ;) (result i32)
+ (func $_main (result i32)
   (local $0 i32)
   (local $1 i32)
   (local.set $0
@@ -388,7 +388,7 @@ total
   )
   (i32.const 0)
  )
- (func $___stdout_write (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+ (func $___stdout_write (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
   (i32.store
    (i32.const 8)
    (local.get $1)
@@ -413,7 +413,7 @@ total
   )
   (i32.const 1)
  )
- (func $__ZNSt3__211__stdoutbufIcE8overflowEi (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+ (func $__ZNSt3__211__stdoutbufIcE8overflowEi (param $0 i32) (param $1 i32) (result i32)
   (i32.store8
    (i32.const 0)
    (local.get $1)
@@ -438,7 +438,7 @@ total
   )
   (i32.const 0)
  )
- (func $__ZNSt3__211__stdoutbufIcE6xsputnEPKci (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+ (func $__ZNSt3__211__stdoutbufIcE6xsputnEPKci (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
   (drop
    (call_indirect (type $0)
     (i32.const 0)
@@ -503,13 +503,13 @@ total
  (elem $0 (i32.const 0) $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $___stdout_write $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $__ZNSt3__211__stdoutbufIcE6xsputnEPKci $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $b0 $__ZNSt3__211__stdoutbufIcE8overflowEi)
  (export "_main" (func $_main))
  (export "_malloc" (func $_malloc))
- (func $b0 (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (param $4 i32) (param $5 i32) (param $6 i32) (result i32)
+ (func $b0 (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (param $4 i32) (param $5 i32) (param $6 i32) (result i32)
   (i32.const 0)
  )
- (func $_malloc (; has Stack IR ;) (param $0 i32) (result i32)
+ (func $_malloc (param $0 i32) (result i32)
   (i32.const 0)
  )
- (func $_main (; has Stack IR ;) (result i32)
+ (func $_main (result i32)
   (local $0 i32)
   (local $1 i32)
   (local.set $0
@@ -614,7 +614,7 @@ total
   )
   (i32.const 0)
  )
- (func $___stdout_write (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+ (func $___stdout_write (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
   (i32.store
    (i32.const 8)
    (local.get $1)
@@ -639,7 +639,7 @@ total
   )
   (i32.const 1)
  )
- (func $__ZNSt3__211__stdoutbufIcE8overflowEi (; has Stack IR ;) (param $0 i32) (param $1 i32) (result i32)
+ (func $__ZNSt3__211__stdoutbufIcE8overflowEi (param $0 i32) (param $1 i32) (result i32)
   (i32.store8
    (i32.const 0)
    (local.get $1)
@@ -664,7 +664,7 @@ total
   )
   (i32.const 0)
  )
- (func $__ZNSt3__211__stdoutbufIcE6xsputnEPKci (; has Stack IR ;) (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+ (func $__ZNSt3__211__stdoutbufIcE6xsputnEPKci (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
   (drop
    (call_indirect (type $0)
     (i32.const 0)
diff --git a/test/passes/fuzz-exec_O.txt b/test/passes/fuzz-exec_O.txt
index 7bdf8d252d1..d636cc765ea 100644
--- a/test/passes/fuzz-exec_O.txt
+++ b/test/passes/fuzz-exec_O.txt
@@ -8,7 +8,7 @@
  (memory $0 1 1)
  (export "func_0" (func $func_0))
  (export "func_1" (func $func_1))
- (func $func_0 (; has Stack IR ;) (result i64)
+ (func $func_0 (result i64)
   (block $label$0 (result i64)
    (br_if $label$0
     (i64.const 1234)
@@ -18,7 +18,7 @@
    )
   )
  )
- (func $func_1 (; has Stack IR ;) (result i32)
+ (func $func_1 (result i32)
   (i32.load16_s offset=22 align=1
    (i32.const -1)
   )
@@ -59,7 +59,7 @@
  (export "add4" (func $div))
  (export "sub1" (func $div))
  (export "sub2" (func $div))
- (func $div (; has Stack IR ;) (result f32)
+ (func $div (result f32)
   (f32.const nan:0x400000)
  )
 )
diff --git a/test/passes/remove-unused-brs_generate-stack-ir_print-stack-ir.txt b/test/passes/remove-unused-brs_generate-stack-ir_print-stack-ir.txt
index c9cacca3978..2eb5aa7da4e 100644
--- a/test/passes/remove-unused-brs_generate-stack-ir_print-stack-ir.txt
+++ b/test/passes/remove-unused-brs_generate-stack-ir_print-stack-ir.txt
@@ -1,23 +1,6 @@
 (module
  (type $0 (func (param i64)))
  (func $0 (param $var$0 i64)
-  block $label$1
-   block $label$2
-    loop $label$3
-     block $label$4
-      unreachable
-     end
-     unreachable
-    end
-    unreachable
-   end
-   unreachable
-  end
- )
-)
-(module
- (type $0 (func (param i64)))
- (func $0 (; has Stack IR ;) (param $var$0 i64)
   (block $label$1
    (br_if $label$1
     (block $label$2
@@ -34,3 +17,20 @@
   )
  )
 )
+(module
+ (type $0 (func (param i64)))
+ (func $0 (param $var$0 i64)
+  block $label$1
+   block $label$2
+    loop $label$3
+     block $label$4
+      unreachable
+     end
+     unreachable
+    end
+    unreachable
+   end
+   unreachable
+  end
+ )
+)
diff --git a/test/unit/test_stack_ir.py b/test/unit/test_stack_ir.py
index 78086d0ccee..191d7eaec29 100644
--- a/test/unit/test_stack_ir.py
+++ b/test/unit/test_stack_ir.py
@@ -7,13 +7,16 @@ class StackIRTest(utils.BinaryenTestCase):
     # test that stack IR opts make a difference.
     def test_stack_ir_opts(self):
         path = self.input_path('stack_ir.wat')
-        opt = shared.run_process(shared.WASM_OPT + [path, '-O', '--generate-stack-ir', '--optimize-stack-ir', '--print-stack-ir', '-o', 'a.wasm'], capture_output=True).stdout
-        nonopt = shared.run_process(shared.WASM_OPT + [path, '-O', '--generate-stack-ir', '--print-stack-ir', '-o', 'b.wasm'], capture_output=True).stdout
+        shared_args = shared.WASM_OPT + [path, '--print-stack-ir']
+        # optimize level 2 will only run some of the stack IR opts. level 3 does
+        # noticeably more.
+        nonopt = shared.run_process(shared_args + ['-o', 'nonopt.wasm', '--optimize-level=2'], capture_output=True).stdout
+        yesopt = shared.run_process(shared_args + ['-o', 'yesopt.wasm', '--optimize-level=3'], capture_output=True).stdout
         # see a difference in the printed stack IR (the optimizations let us
         # remove a pair of local.set/get)
-        self.assertNotEqual(opt, nonopt)
-        self.assertLess(len(opt), len(nonopt))
+        self.assertNotEqual(yesopt, nonopt)
+        self.assertLess(len(yesopt), len(nonopt))
         # see a difference in the actual emitted wasm binary.
-        opt_size = os.path.getsize('a.wasm')
-        nonopt_size = os.path.getsize('b.wasm')
-        self.assertLess(opt_size, nonopt_size)
+        yesopt_size = os.path.getsize('yesopt.wasm')
+        nonopt_size = os.path.getsize('nonopt.wasm')
+        self.assertLess(yesopt_size, nonopt_size)