From 7ede371e87943216817f58dcb523195046926335 Mon Sep 17 00:00:00 2001
From: Erik Eckstein <eeckstein@apple.com>
Date: Mon, 1 Jul 2024 11:49:05 +0200
Subject: [PATCH 1/2] MandatoryPerformanceOptimizations: don't crash with empty
 global-init-once functions

Instead ignore empty global-init-once functions

https://github.com/swiftlang/swift/issues/73487
rdar://130041582
---
 .../ModulePasses/MandatoryPerformanceOptimizations.swift     | 3 +++
 test/SILOptimizer/mandatory_performance_optimizations.sil    | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/SwiftCompilerSources/Sources/Optimizer/ModulePasses/MandatoryPerformanceOptimizations.swift b/SwiftCompilerSources/Sources/Optimizer/ModulePasses/MandatoryPerformanceOptimizations.swift
index 0d206bbe6362f..7236991c8e410 100644
--- a/SwiftCompilerSources/Sources/Optimizer/ModulePasses/MandatoryPerformanceOptimizations.swift
+++ b/SwiftCompilerSources/Sources/Optimizer/ModulePasses/MandatoryPerformanceOptimizations.swift
@@ -355,6 +355,9 @@ private extension Value {
 private extension Function {
   /// Analyzes the global initializer function and returns global it initializes (from `alloc_global` instruction).
   func getInitializedGlobal() -> GlobalVariable? {
+    if !isDefinition {
+      return nil
+    }
     for inst in self.entryBlock.instructions {
       switch inst {
       case let agi as AllocGlobalInst:
diff --git a/test/SILOptimizer/mandatory_performance_optimizations.sil b/test/SILOptimizer/mandatory_performance_optimizations.sil
index 4564548dc5f46..15f622954f5b7 100644
--- a/test/SILOptimizer/mandatory_performance_optimizations.sil
+++ b/test/SILOptimizer/mandatory_performance_optimizations.sil
@@ -167,6 +167,11 @@ bb0:
   return %6 : $()
 }
 
+// Check that we don't crash on global init-once declarations.
+
+// CHECK-LABEL: sil [global_init_once_fn] [no_locks] @external_global_init_once : $@convention(c) () -> ()
+sil [global_init_once_fn] [no_locks] @external_global_init_once : $@convention(c) () -> ()
+
 sil @yield_int_value : $@convention(thin) @yield_once () -> (@yields Int32) {
 bb0:
   %0 = integer_literal $Builtin.Int32, 10

From d4de1a0472b5d5beb85a1a0544378a81d10fe408 Mon Sep 17 00:00:00 2001
From: Erik Eckstein <eeckstein@apple.com>
Date: Mon, 1 Jul 2024 11:49:17 +0200
Subject: [PATCH 2/2] Deserializer: fix a crash with global variables and
 cross-module-optimization

In case of cross-module-optimizations it can happen that a private global variable is changed to public,
but it's declaration is not available in the module file.
---
 lib/Serialization/DeserializeSIL.cpp               | 14 +++++++++++++-
 .../Inputs/cross-module/cross-module.swift         |  6 ++++++
 test/SILOptimizer/cross-module-optimization.swift  |  7 +++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/lib/Serialization/DeserializeSIL.cpp b/lib/Serialization/DeserializeSIL.cpp
index 439f35245545e..e5713a7cced81 100644
--- a/lib/Serialization/DeserializeSIL.cpp
+++ b/lib/Serialization/DeserializeSIL.cpp
@@ -3642,11 +3642,23 @@ SILGlobalVariable *SILDeserializer::readGlobalVar(StringRef Name) {
     return nullptr;
   }
 
+  VarDecl *globalDecl = nullptr;
+  if (dID) {
+    llvm::Expected<Decl *> d = MF->getDeclChecked(dID);
+    if (d) {
+      globalDecl = cast<VarDecl>(d.get());
+    } else {
+      // This can happen with cross-module-optimizations, if the linkage of a
+      // private global variable is changed to public.
+      consumeError(d.takeError());
+    }
+  }
+
   auto Ty = MF->getType(TyID);
   SILGlobalVariable *v = SILGlobalVariable::create(
       SILMod, linkage.value(), SerializedKind_t(serializedKind),
       Name.str(), getSILType(Ty, SILValueCategory::Object, nullptr),
-      std::nullopt, dID ? cast<VarDecl>(MF->getDecl(dID)) : nullptr);
+      std::nullopt, globalDecl);
   v->setLet(IsLet);
   globalVarOrOffset.set(v, true /*isFullyDeserialized*/);
   v->setDeclaration(IsDeclaration);
diff --git a/test/SILOptimizer/Inputs/cross-module/cross-module.swift b/test/SILOptimizer/Inputs/cross-module/cross-module.swift
index 1b657b0622e00..063fc76a2caa0 100644
--- a/test/SILOptimizer/Inputs/cross-module/cross-module.swift
+++ b/test/SILOptimizer/Inputs/cross-module/cross-module.swift
@@ -287,6 +287,12 @@ public func callCImplementationOnly<T>(_ t: T) -> Int {
 
 public let globalLet = 529387
 
+private var privateVar = Int.random(in: 0..<100)
+
+public func getRandom() -> Int {
+  return privateVar
+}
+
 public struct StructWithClosure {
   public static let c = { (x: Int) -> Int in return x }
 }
diff --git a/test/SILOptimizer/cross-module-optimization.swift b/test/SILOptimizer/cross-module-optimization.swift
index b74417195c875..7514aba5de3f3 100644
--- a/test/SILOptimizer/cross-module-optimization.swift
+++ b/test/SILOptimizer/cross-module-optimization.swift
@@ -165,6 +165,12 @@ func testImplementationOnly() {
   // CHECK-SIL2: } // end sil function '$s4Main22testImplementationOnlyyyF'
 }
 
+@inline(never)
+func testPrivateVar() {
+  // CHECK-OUTPUT: {{[0-9]+}}
+  print(getRandom())
+}
+
 testNestedTypes()
 testClass()
 testError()
@@ -175,4 +181,5 @@ testKeypath()
 testMisc()
 testGlobal()
 testImplementationOnly()
+testPrivateVar()