RuntimeLibcalls: Really move default libcall handling to tablegen #148780

arsenm · 2025-07-15T05:22:53Z

Hack in the default setting so it's consistently generated like
the other cases. Maintain a list of targets where this applies.
The alternative would require new infrastructure to sort the system
library initialization in some way.

I wanted the unhandled target case to be treated as a fatal
error, but it turns out there's a hack in IRSymtab using
RuntimeLibcalls, which will fail out in many tests that
do not have a triple set. Many of the failures are simply
running llvm-as with no triple, which probably should not
depend on knowing an accurate set of calls.

arsenm · 2025-07-15T05:23:13Z

RuntimeLibcalls: Really move default libcall handling to tablegen #148780 : 2 dependent PRs (#148782 , #150869 ) 👈 (View in Graphite)
RuntimeLibcalls: Stop opting out of exp10 #148604
RuntimeLibcalls: Mostly move x86 configuration into tablegen #148575
RuntimeLibcalls: Invert handling of 64-bit only libcalls #148571
RuntimeLibcalls: Remove __muloti4 from default libcall set #148562
main

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llvmbot · 2025-07-15T05:23:28Z

@llvm/pr-subscribers-tablegen
@llvm/pr-subscribers-llvm-ir

@llvm/pr-subscribers-backend-x86

Author: Matt Arsenault (arsenm)

Changes

Hack in the default setting so it's consistently generated like
the other cases. Maintain a list of targets where this applies.
The alternative would require new infrastructure to sort the system
library initialization in some way.

I wanted the unhandled target case to be treated as a fatal
error, but it turns out there's a hack in IRSymtab using
RuntimeLibcalls, which will fail out in many tests that
do not have a triple set. Many of the failures are simply
running llvm-as with no triple, which probably should not
depend on knowing an accurate set of calls.

Full diff: https://github.com/llvm/llvm-project/pull/148780.diff

5 Files Affected:

(modified) llvm/include/llvm/IR/RuntimeLibcalls.h (-5)
(modified) llvm/include/llvm/IR/RuntimeLibcalls.td (+33-3)
(modified) llvm/lib/IR/RuntimeLibcalls.cpp (+3-39)
(modified) llvm/test/TableGen/RuntimeLibcallEmitter.td (+1-13)
(modified) llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp (+5-30)

diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.h b/llvm/include/llvm/IR/RuntimeLibcalls.h
index 85db45e27e912..7f04a7f4ab5fd 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.h
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.h
@@ -128,9 +128,6 @@ struct RuntimeLibcallsInfo {
   }
 
 private:
-  static const RTLIB::LibcallImpl
-      DefaultLibcallImpls[RTLIB::UNKNOWN_LIBCALL + 1];
-
   /// Stores the implementation choice for each each libcall.
   RTLIB::LibcallImpl LibcallImpls[RTLIB::UNKNOWN_LIBCALL + 1] = {
       RTLIB::Unsupported};
@@ -178,8 +175,6 @@ struct RuntimeLibcallsInfo {
     return hasSinCos(TT) || TT.isPS();
   }
 
-  LLVM_ABI void initDefaultLibCallImpls();
-
   /// Generated by tablegen.
   void setTargetRuntimeLibcallSets(const Triple &TT,
                                    FloatABI::ABIType FloatABI);
diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.td b/llvm/include/llvm/IR/RuntimeLibcalls.td
index 8ab63bd3d6b93..af339e2a55cf2 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.td
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.td
@@ -1581,7 +1581,9 @@ def HexagonSystemLibrary
     (add (sub DefaultLibcallImpls32,
     __adddf3, __divsf3, __udivsi3, __udivdi3,
     __umoddi3, __divdf3, __muldf3, __divsi3, __subdf3, sqrtf,
-    __divdi3, __umodsi3, __moddi3, __modsi3), HexagonLibcalls)>;
+    __divdi3, __umodsi3, __moddi3, __modsi3), HexagonLibcalls,
+    LibmHasSinCosF32, LibmHasSinCosF64, LibmHasSinCosF128,
+    exp10f, exp10, exp10l_f128)>;
 
 //===----------------------------------------------------------------------===//
 // Lanai Runtime Libcalls
@@ -2128,8 +2130,12 @@ def __memcpy_4 : RuntimeLibcallImpl<MEMCPY_ALIGN_4>;
 
 def isXCore : RuntimeLibcallPredicate<"TT.getArch() == Triple::xcore">;
 def XCoreSystemLibrary
-    : SystemRuntimeLibrary<isXCore, (add DefaultRuntimeLibcallImpls,
-                                        __memcpy_4)>;
+    : SystemRuntimeLibrary<isXCore,
+    (add DefaultRuntimeLibcallImpls,
+         exp10f, exp10, exp10l_f128,
+         __memcpy_4,
+         LibcallImpls<(add LibmF128Libcalls, LibmF128FiniteLibcalls), isGNUEnvironment>
+)>;
 
 //===----------------------------------------------------------------------===//
 // ZOS Runtime Libcalls
@@ -2246,3 +2252,27 @@ def WasmSystemLibrary
            CompilerRTOnlyInt64Libcalls, CompilerRTOnlyInt128Libcalls,
            exp10f, exp10,
            emscripten_return_address)>;
+
+//===----------------------------------------------------------------------===//
+// Legacy Default Runtime Libcalls
+//===----------------------------------------------------------------------===//
+
+// TODO: Should make every target explicit.
+def isDefaultLibcallArch : RuntimeLibcallPredicate<[{
+  TT.isMIPS() || TT.isLoongArch() || TT.isVE() || TT.isBPF() ||
+  TT.getArch() == Triple::csky || TT.getArch() == Triple::arc ||
+  TT.getArch() == Triple::m68k ||  TT.getArch() == Triple::xtensa ||
+  (TT.isSystemZ() && !TT.isOSzOS()) ||
+  TT.isSPIRV() || TT.isDXIL()
+}]>;
+
+
+def isArch64Bit : RuntimeLibcallPredicate<[{TT.isArch64Bit()}]>;
+def LegacyDefaultSystemLibrary
+    : SystemRuntimeLibrary<isDefaultLibcallArch,
+      (add DefaultRuntimeLibcallImpls,
+         LibmHasSinCosF32, LibmHasSinCosF64, LibmHasSinCosF128,
+         exp10f, exp10, exp10l_f128,
+         __powisf2, __powidf2, __powitf2_f128,
+         LibcallImpls<(add Int128RTLibcalls), isArch64Bit>
+)>;
diff --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp
index e3e62726f54bc..b389ab0187d2a 100644
--- a/llvm/lib/IR/RuntimeLibcalls.cpp
+++ b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -8,6 +8,9 @@
 
 #include "llvm/IR/RuntimeLibcalls.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "runtime-libcalls-info"
 
 using namespace llvm;
 using namespace RTLIB;
@@ -62,12 +65,6 @@ static void setARMLibcallNames(RuntimeLibcallsInfo &Info, const Triple &TT,
     Info.setLibcallImplCallingConv(Impl, CallingConv::ARM_AAPCS);
 }
 
-void RTLIB::RuntimeLibcallsInfo::initDefaultLibCallImpls() {
-  std::memcpy(LibcallImpls, DefaultLibcallImpls, sizeof(LibcallImpls));
-  static_assert(sizeof(LibcallImpls) == sizeof(DefaultLibcallImpls),
-                "libcall array size should match");
-}
-
 /// Set default libcall names. If a target wants to opt-out of a libcall it
 /// should be placed here.
 void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
@@ -76,10 +73,6 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
                                        EABI EABIVersion, StringRef ABIName) {
   setTargetRuntimeLibcallSets(TT, FloatABI);
 
-  // Early exit for targets that have fully ported to tablegen.
-  if (TT.isAMDGPU() || TT.isNVPTX() || TT.isWasm())
-    return;
-
   if (TT.isX86() || TT.isVE() || TT.isARM() || TT.isThumb()) {
     if (ExceptionModel == ExceptionHandling::SjLj)
       setLibcallImpl(RTLIB::UNWIND_RESUME, RTLIB::_Unwind_SjLj_Resume);
@@ -92,46 +85,17 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
     // FIXME: What about other targets?
     setLibcallImpl(RTLIB::FPEXT_F16_F32, RTLIB::__extendhfsf2);
     setLibcallImpl(RTLIB::FPROUND_F32_F16, RTLIB::__truncsfhf2);
-
-    if (!darwinHasExp10(TT)) {
-      setLibcallImpl(RTLIB::EXP10_F32, RTLIB::Unsupported);
-      setLibcallImpl(RTLIB::EXP10_F64, RTLIB::Unsupported);
-    }
   }
 
   if (TT.isOSOpenBSD()) {
     setLibcallImpl(RTLIB::STACKPROTECTOR_CHECK_FAIL, RTLIB::Unsupported);
   }
 
-  // Skip default manual processing for targets that have been mostly ported to
-  // tablegen for now. Eventually the rest of this should be deleted.
-  if (TT.isX86() || TT.isAArch64() || TT.isWasm() || TT.isPPC())
-    return;
-
   if (TT.isARM() || TT.isThumb()) {
     setARMLibcallNames(*this, TT, FloatABI, EABIVersion);
     return;
   }
 
-  if (hasSinCos(TT)) {
-    setLibcallImpl(RTLIB::SINCOS_F32, RTLIB::sincosf);
-    setLibcallImpl(RTLIB::SINCOS_F64, RTLIB::sincos);
-    setLibcallImpl(RTLIB::SINCOS_F128, RTLIB::sincos_f128);
-  }
-
-  setLibcallImpl(RTLIB::EXP10_F32, RTLIB::exp10f);
-  setLibcallImpl(RTLIB::EXP10_F64, RTLIB::exp10);
-  setLibcallImpl(RTLIB::EXP10_F128, RTLIB::exp10l_f128);
-
-  // These libcalls are only available in compiler-rt, not libgcc.
-  if (TT.isArch64Bit()) {
-    setLibcallImpl(RTLIB::SHL_I128, RTLIB::__ashlti3);
-    setLibcallImpl(RTLIB::SRL_I128, RTLIB::__lshrti3);
-    setLibcallImpl(RTLIB::SRA_I128, RTLIB::__ashrti3);
-    setLibcallImpl(RTLIB::MUL_I128, RTLIB::__multi3);
-    setLibcallImpl(RTLIB::MULO_I64, RTLIB::__mulodi4);
-  }
-
   if (TT.getArch() == Triple::ArchType::msp430) {
     setLibcallImplCallingConv(RTLIB::__mspabi_mpyll,
                               CallingConv::MSP430_BUILTIN);
diff --git a/llvm/test/TableGen/RuntimeLibcallEmitter.td b/llvm/test/TableGen/RuntimeLibcallEmitter.td
index a0061afab1db0..61c0468fbb7a1 100644
--- a/llvm/test/TableGen/RuntimeLibcallEmitter.td
+++ b/llvm/test/TableGen/RuntimeLibcallEmitter.td
@@ -104,18 +104,6 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
 // CHECK-NEXT: #endif
 
 // CHECK: #ifdef GET_INIT_RUNTIME_LIBCALL_NAMES
-// CHECK-NEXT: const RTLIB::LibcallImpl llvm::RTLIB::RuntimeLibcallsInfo::DefaultLibcallImpls[RTLIB::UNKNOWN_LIBCALL + 1] = {
-// CHECK-NEXT:   RTLIB::Unsupported, // RTLIB::BZERO
-// CHECK-NEXT:   RTLIB::Unsupported, // RTLIB::CALLOC
-// CHECK-NEXT:   RTLIB::Unsupported, // RTLIB::MEMCPY
-// CHECK-NEXT:   RTLIB::Unsupported, // RTLIB::MEMSET
-// CHECK-NEXT:   RTLIB::__ashlsi3, // RTLIB::SHL_I32
-// CHECK-NEXT:   RTLIB::sqrtl_f80, // RTLIB::SQRT_F80
-// CHECK-NEXT:   RTLIB::sqrtl_f128, // RTLIB::SQRT_F128
-// CHECK-NEXT:   RTLIB::__lshrdi3, // RTLIB::SRL_I64
-// CHECK-NEXT:   RTLIB::Unsupported
-// CHECK-NEXT: };
-// CHECK-EMPTY:
 // CHECK-NEXT: const char *const llvm::RTLIB::RuntimeLibcallsInfo::LibCallImplNames[RTLIB::NumLibcallImpls] = {
 // CHECK-NEXT: nullptr, // RTLIB::Unsupported
 // CHECK-NEXT: "___memcpy", // RTLIB::___memcpy
@@ -236,7 +224,7 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
 // CHECK-EMPTY:
 // CHECK-NEXT:   return;
 // CHECK-NEXT: }
-// CHECK-NEXT:  initDefaultLibCallImpls();
+// CHECK-NEXT:  LLVM_DEBUG(dbgs() << "no system runtime library applied to target \'" << TT.str() << "\'\n");
 // CHECK-NEXT: }
 // CHECK-EMPTY:
 // CHECK: #endif
diff --git a/llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp b/llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp
index 68bd1b5c9cb21..11f2075263a94 100644
--- a/llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp
+++ b/llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp
@@ -307,29 +307,6 @@ void RuntimeLibcallEmitter::emitGetInitRuntimeLibcallNames(
     raw_ostream &OS) const {
   // TODO: Emit libcall names as string offset table.
 
-  OS << "const RTLIB::LibcallImpl "
-        "llvm::RTLIB::RuntimeLibcallsInfo::"
-        "DefaultLibcallImpls[RTLIB::UNKNOWN_LIBCALL + 1] = {\n";
-
-  for (const RuntimeLibcall &LibCall : RuntimeLibcallDefList) {
-    auto I = LibCallToDefaultImpl.find(&LibCall);
-    if (I == LibCallToDefaultImpl.end()) {
-      OS << "  RTLIB::Unsupported,";
-    } else {
-      const RuntimeLibcallImpl *LibCallImpl = I->second;
-      OS << "  ";
-      LibCallImpl->emitEnumEntry(OS);
-      OS << ',';
-    }
-
-    OS << " // ";
-    LibCall.emitEnumEntry(OS);
-    OS << '\n';
-  }
-
-  OS << "  RTLIB::Unsupported\n"
-        "};\n\n";
-
   // Emit the implementation names
   OS << "const char *const llvm::RTLIB::RuntimeLibcallsInfo::"
         "LibCallImplNames[RTLIB::NumLibcallImpls] = {\n"
@@ -528,13 +505,11 @@ void RuntimeLibcallEmitter::emitSystemRuntimeLibrarySetCalls(
     TopLevelPredicate.emitEndIf(OS);
   }
 
-  // Fallback to the old default set for manual table entries.
-  //
-  // TODO: Remove this when targets have switched to using generated tables by
-  // default.
-  OS << "  initDefaultLibCallImpls();\n";
-
-  OS << "}\n\n";
+  // FIXME: This should be a fatal error. A few contexts are improperly relying
+  // on RuntimeLibcalls constructed with fully unknown triples.
+  OS << "  LLVM_DEBUG(dbgs() << \"no system runtime library applied to target "
+        "\\'\" << TT.str() << \"\\'\\n\");\n"
+        "}\n\n";
 }
 
 void RuntimeLibcallEmitter::run(raw_ostream &OS) {

llvm/include/llvm/IR/RuntimeLibcalls.td

nikic

Is dropping sincos on AVR here intentional?

arsenm · 2025-08-03T15:22:03Z

Is dropping sincos on AVR here intentional?

Yes, I had a PR to add baseline tests and apparently there's no Linux or gnu system to worry about

arsenm · 2025-08-03T15:31:34Z

AVR also has the strange reuse of the f64 names for the f32 sin and cos

Hack in the default setting so it's consistently generated like the other cases. Maintain a list of targets where this applies. The alternative would require new infrastructure to sort the system library initialization in some way. I wanted the unhandled target case to be treated as a fatal error, but it turns out there's a hack in IRSymtab using RuntimeLibcalls, which will fail out in many tests that do not have a triple set. Many of the failures are simply running llvm-as with no triple, which probably should not depend on knowing an accurate set of calls.

tgross35 · 2025-08-03T16:47:01Z

AVR also has the strange reuse of the f64 names for the f32 sin and cos

I haven’t looked but would guess this platform and MSP have pretty much the same issue as f128 on 32-bit/x86, since float and double are the same size. If there was a way to indicate that a C23 math library was available (from the other PR threads), some of this could be resolved by always emitting sqrtf32 and sqrtf64 for binary32 and binary64 float.

Not that many people are using f64/f128 on AVR, some of the math routines are the entire flash space…

arsenm · 2025-08-03T16:51:49Z

AVR also has the strange reuse of the f64 names for the f32 sin and cos

I haven’t looked but would guess this platform and MSP have pretty much the same issue as f128 on 32-bit/x86, since float and double are the same size.

I'm not really sure what the issue is. The implementation is very underdeveloped if it's that broad. The starting state only bothered to handle sin and cos

nikic

LGTM. Looks like the behavior changes on AVR, MSP430 and XCore are intentional.

tgross35 · 2025-08-04T17:42:20Z

I'm not really sure what the issue is. The implementation is very underdeveloped if it's that broad. The starting state only bothered to handle sin and cos

There is no issue in the PR here, this looks fine. The problem is when trying to use LLVM's double which AIUI is always f64, but platform double on AVR is f32. So llvm.*.f64 calls symbol sqrt with a f64, but that's a f32 symbol on the platform https://llvm.godbolt.org/z/f6sdP4MxT. (Basically the same problem as with f128 using long double symbols). The only way to resolve it is to lower LLVM's double math to C23 sqrtf64 rather than sqrt on AVR.

Underdeveloped is accurate here, it's not relevant for a whole lot of users.

arsenm added backend:X86 llvm:ir labels Jul 15, 2025 — with Graphite App

This was referenced Jul 15, 2025

RuntimeLibcalls: Remove __muloti4 from default libcall set #148562

Merged

RuntimeLibcalls: Invert handling of 64-bit only libcalls #148571

Merged

RuntimeLibcalls: Mostly move x86 configuration into tablegen #148575

Merged

arsenm mentioned this pull request Jul 15, 2025

RuntimeLibcalls: Stop opting out of exp10 #148604

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arsenm requested review from DanielKristofKiss, dpaoliello, efriedma-quic, nikic and RKSimon July 15, 2025 05:23

arsenm marked this pull request as ready for review July 15, 2025 05:23

llvmbot added the tablegen label Jul 15, 2025

arsenm commented Jul 15, 2025

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arsenm force-pushed the users/arsenm/runtime-libcalls/use-tablegen-default-handling branch from 14d4d03 to ef419d6 Compare July 15, 2025 06:19

arsenm force-pushed the users/arsenm/runtime-libcalls/stop-opt-out-exp10 branch from a64799d to c35ac3c Compare July 15, 2025 06:19

This was referenced Jul 15, 2025

RuntimeLibcalls: Remove darwin override of half convert libcalls #148782

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RuntimeLibcalls: Move __stack_chk_fail config to tablegen #148789

Merged

RuntimeLibcalls: Remove target check for sjlj config #148792

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arsenm force-pushed the users/arsenm/runtime-libcalls/stop-opt-out-exp10 branch from c35ac3c to 465db65 Compare July 15, 2025 07:20

arsenm force-pushed the users/arsenm/runtime-libcalls/use-tablegen-default-handling branch from ef419d6 to f5462a6 Compare July 15, 2025 07:20

arsenm force-pushed the users/arsenm/runtime-libcalls/stop-opt-out-exp10 branch from 465db65 to 9c031f5 Compare July 28, 2025 02:43

arsenm force-pushed the users/arsenm/runtime-libcalls/use-tablegen-default-handling branch from f5462a6 to 5843fba Compare July 28, 2025 02:43

This was referenced Jul 28, 2025

RuntimeLibcalls: Add bitset for available libcalls #150869

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RuntimeLibcalls: Move __stack_smash_handler config to tablegen #150870

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arsenm force-pushed the users/arsenm/runtime-libcalls/stop-opt-out-exp10 branch from 9c031f5 to b1c46d2 Compare August 3, 2025 00:41

arsenm force-pushed the users/arsenm/runtime-libcalls/use-tablegen-default-handling branch from 5843fba to a8d3505 Compare August 3, 2025 00:41

Base automatically changed from users/arsenm/runtime-libcalls/stop-opt-out-exp10 to main August 3, 2025 15:08

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arsenm force-pushed the users/arsenm/runtime-libcalls/use-tablegen-default-handling branch from a8d3505 to 744161e Compare August 3, 2025 16:32

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arsenm merged commit b2f0ffd into main Aug 3, 2025
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