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Merged
merged 1 commit into from
Mar 11, 2025
Merged

Reland "[clang] Lower modf builtin using llvm.modf intrinsic" #130761

merged 1 commit into from
Mar 11, 2025

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@MacDue MacDue commented Mar 11, 2025

Reverts c40f0fe

Original description:
This updates the existing modf[f|l] builtin to be lowered via the llvm.modf.* intrinsic (rather than directly to a library call).

The Windows 32-bit x86 missing modff symbol issue should have been solved in: #130636.

@MacDue MacDue added the skip-precommit-approval PR for CI feedback, not intended for review label Mar 11, 2025
@llvmbot llvmbot added clang Clang issues not falling into any other category backend:X86 clang:codegen IR generation bugs: mangling, exceptions, etc. labels Mar 11, 2025
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llvmbot commented Mar 11, 2025 •
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@llvm/pr-subscribers-clang-codegen

@llvm/pr-subscribers-backend-x86

Author: Benjamin Maxwell (MacDue)

Changes

Reverts c40f0fe

Original description:
This updates the existing modf[f|l] builtin to be lowered via the llvm.modf.* intrinsic (rather than directly to a library call).

The Windows 32-bit x86 missing modff symbol issue should have been solved in: #130636.

Full diff: https://github.com/llvm/llvm-project/pull/130761.diff

6 Files Affected:

  • (modified) clang/lib/CodeGen/CGBuiltin.cpp (+27)
  • (modified) clang/test/CodeGen/X86/math-builtins.c (+25-7)
  • (modified) clang/test/CodeGen/aix-builtin-mapping.c (+1-1)
  • (modified) clang/test/CodeGen/builtin-attributes.c (+8-3)
  • (modified) clang/test/CodeGen/math-builtins-long.c (+3-3)
  • (modified) clang/test/CodeGen/math-libcalls.c (+6-6)
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 167bd6e4695c1..ba78de049ce96 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -859,6 +859,24 @@ static void emitSincosBuiltin(CodeGenFunction &CGF, const CallExpr *E,
   StoreCos->setMetadata(LLVMContext::MD_noalias, AliasScopeList);
 }
 
+static llvm::Value *emitModfBuiltin(CodeGenFunction &CGF, const CallExpr *E,
+                                    llvm::Intrinsic::ID IntrinsicID) {
+  llvm::Value *Val = CGF.EmitScalarExpr(E->getArg(0));
+  llvm::Value *IntPartDest = CGF.EmitScalarExpr(E->getArg(1));
+
+  llvm::Value *Call =
+      CGF.Builder.CreateIntrinsic(IntrinsicID, {Val->getType()}, Val);
+
+  llvm::Value *FractionalResult = CGF.Builder.CreateExtractValue(Call, 0);
+  llvm::Value *IntegralResult = CGF.Builder.CreateExtractValue(Call, 1);
+
+  QualType DestPtrType = E->getArg(1)->getType()->getPointeeType();
+  LValue IntegralLV = CGF.MakeNaturalAlignAddrLValue(IntPartDest, DestPtrType);
+  CGF.EmitStoreOfScalar(IntegralResult, IntegralLV);
+
+  return FractionalResult;
+}
+
 /// EmitFAbs - Emit a call to @llvm.fabs().
 static Value *EmitFAbs(CodeGenFunction &CGF, Value *V) {
   Function *F = CGF.CGM.getIntrinsic(Intrinsic::fabs, V->getType());
@@ -4120,6 +4138,15 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BI__builtin_frexpf128:
   case Builtin::BI__builtin_frexpf16:
     return RValue::get(emitFrexpBuiltin(*this, E, Intrinsic::frexp));
+  case Builtin::BImodf:
+  case Builtin::BImodff:
+  case Builtin::BImodfl:
+  case Builtin::BI__builtin_modf:
+  case Builtin::BI__builtin_modff:
+  case Builtin::BI__builtin_modfl:
+    if (Builder.getIsFPConstrained())
+      break; // TODO: Emit constrained modf intrinsic once one exists.
+    return RValue::get(emitModfBuiltin(*this, E, Intrinsic::modf));
   case Builtin::BI__builtin_isgreater:
   case Builtin::BI__builtin_isgreaterequal:
   case Builtin::BI__builtin_isless:
diff --git a/clang/test/CodeGen/X86/math-builtins.c b/clang/test/CodeGen/X86/math-builtins.c
index 481d3c043683e..8a85d1f6c3a76 100644
--- a/clang/test/CodeGen/X86/math-builtins.c
+++ b/clang/test/CodeGen/X86/math-builtins.c
@@ -38,6 +38,24 @@ void foo(double *d, float f, float *fp, long double *l, int *i, const char *c) {
 // NO__ERRNO-NEXT: [[FREXP_F128_0:%.+]] = extractvalue { fp128, i32 } [[FREXP_F128]], 0
 
 
+// NO__ERRNO: [[MODF_F64:%.+]] = call { double, double } @llvm.modf.f64(double %{{.+}})
+// NO__ERRNO-NEXT: [[MODF_F64_FP:%.+]] = extractvalue { double, double } [[MODF_F64]], 0
+// NO__ERRNO-NEXT: [[MODF_F64_IP:%.+]] = extractvalue { double, double } [[MODF_F64]], 1
+// NO__ERRNO-NEXT: store double [[MODF_F64_IP]], ptr %{{.+}}, align 8
+
+// NO__ERRNO: [[MODF_F32:%.+]] = call { float, float } @llvm.modf.f32(float %{{.+}})
+// NO__ERRNO-NEXT: [[MODF_F32_FP:%.+]] = extractvalue { float, float } [[MODF_F32]], 0
+// NO__ERRNO-NEXT: [[MODF_F32_IP:%.+]] = extractvalue { float, float } [[MODF_F32]], 1
+// NO__ERRNO-NEXT: store float [[MODF_F32_IP]], ptr %{{.+}}, align 4
+
+// NO__ERRNO: [[MODF_F80:%.+]] = call { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80 %{{.+}})
+// NO__ERRNO-NEXT: [[MODF_F80_FP:%.+]] = extractvalue { x86_fp80, x86_fp80 } [[MODF_F80]], 0
+// NO__ERRNO-NEXT: [[MODF_F80_IP:%.+]] = extractvalue { x86_fp80, x86_fp80 } [[MODF_F80]], 1
+// NO__ERRNO-NEXT: store x86_fp80 [[MODF_F80_IP]], ptr %{{.+}}, align 16
+
+// NO__ERRNO: call fp128 @modff128(fp128 noundef %{{.+}}, ptr noundef %{{.+}})
+
+
 // NO__ERRNO: [[SINCOS_F64:%.+]] = call { double, double } @llvm.sincos.f64(double %{{.+}})
 // NO__ERRNO-NEXT: [[SINCOS_F64_0:%.+]] = extractvalue { double, double } [[SINCOS_F64]], 0
 // NO__ERRNO-NEXT: [[SINCOS_F64_1:%.+]] = extractvalue { double, double } [[SINCOS_F64]], 1
@@ -158,13 +176,13 @@ void foo(double *d, float f, float *fp, long double *l, int *i, const char *c) {
 
   __builtin_modf(f,d);       __builtin_modff(f,fp);      __builtin_modfl(f,l); __builtin_modff128(f,l);
 
-// NO__ERRNO: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE:#[0-9]+]]
-// NO__ERRNO: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
-// NO__ERRNO: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]
-// NO__ERRNO: declare fp128 @modff128(fp128 noundef, ptr noundef) [[NOT_READNONE]]
-// HAS_ERRNO: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE]]
-// HAS_ERRNO: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
-// HAS_ERRNO: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]
+// NO__ERRNO: declare { double, double } @llvm.modf.f64(double) [[READNONE_INTRINSIC]]
+// NO__ERRNO: declare { float, float } @llvm.modf.f32(float) [[READNONE_INTRINSIC]]
+// NO__ERRNO: declare { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80) [[READNONE_INTRINSIC]]
+// NO__ERRNO: declare fp128 @modff128(fp128 noundef, ptr noundef) [[NOT_READNONE:#[0-9]+]]
+// HAS_ERRNO: declare { double, double } @llvm.modf.f64(double) [[READNONE_INTRINSIC]]
+// HAS_ERRNO: declare { float, float } @llvm.modf.f32(float) [[READNONE_INTRINSIC]]
+// HAS_ERRNO: declare { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80) [[READNONE_INTRINSIC]]
 // HAS_ERRNO: declare fp128 @modff128(fp128 noundef, ptr noundef) [[NOT_READNONE]]
 
   __builtin_nan(c);        __builtin_nanf(c);       __builtin_nanl(c); __builtin_nanf128(c);
diff --git a/clang/test/CodeGen/aix-builtin-mapping.c b/clang/test/CodeGen/aix-builtin-mapping.c
index a79218c6f1d8b..cc1cc1a44f32c 100644
--- a/clang/test/CodeGen/aix-builtin-mapping.c
+++ b/clang/test/CodeGen/aix-builtin-mapping.c
@@ -17,6 +17,6 @@ int main()
   returnValue = __builtin_ldexpl(1.0L, 1);
 }
 
-// CHECK: %call = call double @modf(double noundef 1.000000e+00, ptr noundef %DummyLongDouble) #3
+// CHECK: %{{.+}} = call { double, double } @llvm.modf.f64(double 1.000000e+00)
 // CHECK: %{{.+}} = call { double, i32 } @llvm.frexp.f64.i32(double 0.000000e+00)
 // CHECK: %{{.+}} = call double @llvm.ldexp.f64.i32(double 1.000000e+00, i32 1)
diff --git a/clang/test/CodeGen/builtin-attributes.c b/clang/test/CodeGen/builtin-attributes.c
index e5b0faccfd23f..506b165fcf36e 100644
--- a/clang/test/CodeGen/builtin-attributes.c
+++ b/clang/test/CodeGen/builtin-attributes.c
@@ -24,6 +24,11 @@ char* f2(char* a, char* b) {
   return __builtin_strstr(a, b);
 }
 
+// Note: Use asm label to disable intrinsic lowering of modf.
+double modf(double x, double*) asm("modf");
+float modff(float x, float*) asm("modff");
+long double modfl(long double x, long double*) asm("modfl");
+
 // frexp is NOT readnone. It writes to its pointer argument.
 //
 // CHECK: f3
@@ -55,9 +60,9 @@ int f3(double x) {
   frexp(x, &e);
   frexpf(x, &e);
   frexpl(x, &e);
-  __builtin_modf(x, &e);
-  __builtin_modff(x, &e);
-  __builtin_modfl(x, &e);
+  modf(x, &e);
+  modff(x, &e);
+  modfl(x, &e);
   __builtin_remquo(x, x, &e);
   __builtin_remquof(x, x, &e);
   __builtin_remquol(x, x, &e);
diff --git a/clang/test/CodeGen/math-builtins-long.c b/clang/test/CodeGen/math-builtins-long.c
index 183349e0f0173..87e64a2eaa1c3 100644
--- a/clang/test/CodeGen/math-builtins-long.c
+++ b/clang/test/CodeGen/math-builtins-long.c
@@ -58,9 +58,9 @@ void foo(long double f, long double *l, int *i, const char *c) {
   // PPCF128: call fp128 @ldexpf128(fp128 noundef %{{.+}}, {{(signext)?.+}})
   __builtin_ldexpl(f,f);
 
-  // F80: call x86_fp80 @modfl(x86_fp80 noundef %{{.+}}, ptr noundef %{{.+}})
-  // PPC: call ppc_fp128 @modfl(ppc_fp128 noundef %{{.+}}, ptr noundef %{{.+}})
-  // X86F128: call fp128 @modfl(fp128 noundef %{{.+}}, ptr noundef %{{.+}})
+  // F80: call { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80 %{{.+}})
+  // PPC: call { ppc_fp128, ppc_fp128 } @llvm.modf.ppcf128(ppc_fp128 %{{.+}})
+  // X86F128: call { fp128, fp128 } @llvm.modf.f128(fp128 %{{.+}})
   // PPCF128: call fp128 @modff128(fp128 noundef %{{.+}}, ptr noundef %{{.+}})
   __builtin_modfl(f,l);
 
diff --git a/clang/test/CodeGen/math-libcalls.c b/clang/test/CodeGen/math-libcalls.c
index 14fdee77f4d78..ad297828f48ed 100644
--- a/clang/test/CodeGen/math-libcalls.c
+++ b/clang/test/CodeGen/math-libcalls.c
@@ -83,12 +83,12 @@ void foo(double *d, float f, float *fp, long double *l, int *i, const char *c) {
 
   modf(f,d);       modff(f,fp);      modfl(f,l);
 
-  // NO__ERRNO: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE]]
-  // NO__ERRNO: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
-  // NO__ERRNO: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]
-  // HAS_ERRNO: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE]]
-  // HAS_ERRNO: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
-  // HAS_ERRNO: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]
+  // NO__ERRNO: declare { double, double } @llvm.modf.f64(double) [[READNONE_INTRINSIC]]
+  // NO__ERRNO: declare { float, float } @llvm.modf.f32(float) [[READNONE_INTRINSIC]]
+  // NO__ERRNO: declare { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80) [[READNONE_INTRINSIC]]
+  // HAS_ERRNO: declare { double, double } @llvm.modf.f64(double) [[READNONE_INTRINSIC]]
+  // HAS_ERRNO: declare { float, float } @llvm.modf.f32(float) [[READNONE_INTRINSIC]]
+  // HAS_ERRNO: declare { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80) [[READNONE_INTRINSIC]]
   // HAS_MAYTRAP: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE]]
   // HAS_MAYTRAP: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
   // HAS_MAYTRAP: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]

@llvmbot
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llvmbot commented Mar 11, 2025

@llvm/pr-subscribers-clang

Author: Benjamin Maxwell (MacDue)

Changes

Reverts c40f0fe

Original description:
This updates the existing modf[f|l] builtin to be lowered via the llvm.modf.* intrinsic (rather than directly to a library call).

The Windows 32-bit x86 missing modff symbol issue should have been solved in: #130636.

Full diff: https://github.com/llvm/llvm-project/pull/130761.diff

6 Files Affected:

  • (modified) clang/lib/CodeGen/CGBuiltin.cpp (+27)
  • (modified) clang/test/CodeGen/X86/math-builtins.c (+25-7)
  • (modified) clang/test/CodeGen/aix-builtin-mapping.c (+1-1)
  • (modified) clang/test/CodeGen/builtin-attributes.c (+8-3)
  • (modified) clang/test/CodeGen/math-builtins-long.c (+3-3)
  • (modified) clang/test/CodeGen/math-libcalls.c (+6-6)
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 167bd6e4695c1..ba78de049ce96 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -859,6 +859,24 @@ static void emitSincosBuiltin(CodeGenFunction &CGF, const CallExpr *E,
   StoreCos->setMetadata(LLVMContext::MD_noalias, AliasScopeList);
 }
 
+static llvm::Value *emitModfBuiltin(CodeGenFunction &CGF, const CallExpr *E,
+                                    llvm::Intrinsic::ID IntrinsicID) {
+  llvm::Value *Val = CGF.EmitScalarExpr(E->getArg(0));
+  llvm::Value *IntPartDest = CGF.EmitScalarExpr(E->getArg(1));
+
+  llvm::Value *Call =
+      CGF.Builder.CreateIntrinsic(IntrinsicID, {Val->getType()}, Val);
+
+  llvm::Value *FractionalResult = CGF.Builder.CreateExtractValue(Call, 0);
+  llvm::Value *IntegralResult = CGF.Builder.CreateExtractValue(Call, 1);
+
+  QualType DestPtrType = E->getArg(1)->getType()->getPointeeType();
+  LValue IntegralLV = CGF.MakeNaturalAlignAddrLValue(IntPartDest, DestPtrType);
+  CGF.EmitStoreOfScalar(IntegralResult, IntegralLV);
+
+  return FractionalResult;
+}
+
 /// EmitFAbs - Emit a call to @llvm.fabs().
 static Value *EmitFAbs(CodeGenFunction &CGF, Value *V) {
   Function *F = CGF.CGM.getIntrinsic(Intrinsic::fabs, V->getType());
@@ -4120,6 +4138,15 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BI__builtin_frexpf128:
   case Builtin::BI__builtin_frexpf16:
     return RValue::get(emitFrexpBuiltin(*this, E, Intrinsic::frexp));
+  case Builtin::BImodf:
+  case Builtin::BImodff:
+  case Builtin::BImodfl:
+  case Builtin::BI__builtin_modf:
+  case Builtin::BI__builtin_modff:
+  case Builtin::BI__builtin_modfl:
+    if (Builder.getIsFPConstrained())
+      break; // TODO: Emit constrained modf intrinsic once one exists.
+    return RValue::get(emitModfBuiltin(*this, E, Intrinsic::modf));
   case Builtin::BI__builtin_isgreater:
   case Builtin::BI__builtin_isgreaterequal:
   case Builtin::BI__builtin_isless:
diff --git a/clang/test/CodeGen/X86/math-builtins.c b/clang/test/CodeGen/X86/math-builtins.c
index 481d3c043683e..8a85d1f6c3a76 100644
--- a/clang/test/CodeGen/X86/math-builtins.c
+++ b/clang/test/CodeGen/X86/math-builtins.c
@@ -38,6 +38,24 @@ void foo(double *d, float f, float *fp, long double *l, int *i, const char *c) {
 // NO__ERRNO-NEXT: [[FREXP_F128_0:%.+]] = extractvalue { fp128, i32 } [[FREXP_F128]], 0
 
 
+// NO__ERRNO: [[MODF_F64:%.+]] = call { double, double } @llvm.modf.f64(double %{{.+}})
+// NO__ERRNO-NEXT: [[MODF_F64_FP:%.+]] = extractvalue { double, double } [[MODF_F64]], 0
+// NO__ERRNO-NEXT: [[MODF_F64_IP:%.+]] = extractvalue { double, double } [[MODF_F64]], 1
+// NO__ERRNO-NEXT: store double [[MODF_F64_IP]], ptr %{{.+}}, align 8
+
+// NO__ERRNO: [[MODF_F32:%.+]] = call { float, float } @llvm.modf.f32(float %{{.+}})
+// NO__ERRNO-NEXT: [[MODF_F32_FP:%.+]] = extractvalue { float, float } [[MODF_F32]], 0
+// NO__ERRNO-NEXT: [[MODF_F32_IP:%.+]] = extractvalue { float, float } [[MODF_F32]], 1
+// NO__ERRNO-NEXT: store float [[MODF_F32_IP]], ptr %{{.+}}, align 4
+
+// NO__ERRNO: [[MODF_F80:%.+]] = call { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80 %{{.+}})
+// NO__ERRNO-NEXT: [[MODF_F80_FP:%.+]] = extractvalue { x86_fp80, x86_fp80 } [[MODF_F80]], 0
+// NO__ERRNO-NEXT: [[MODF_F80_IP:%.+]] = extractvalue { x86_fp80, x86_fp80 } [[MODF_F80]], 1
+// NO__ERRNO-NEXT: store x86_fp80 [[MODF_F80_IP]], ptr %{{.+}}, align 16
+
+// NO__ERRNO: call fp128 @modff128(fp128 noundef %{{.+}}, ptr noundef %{{.+}})
+
+
 // NO__ERRNO: [[SINCOS_F64:%.+]] = call { double, double } @llvm.sincos.f64(double %{{.+}})
 // NO__ERRNO-NEXT: [[SINCOS_F64_0:%.+]] = extractvalue { double, double } [[SINCOS_F64]], 0
 // NO__ERRNO-NEXT: [[SINCOS_F64_1:%.+]] = extractvalue { double, double } [[SINCOS_F64]], 1
@@ -158,13 +176,13 @@ void foo(double *d, float f, float *fp, long double *l, int *i, const char *c) {
 
   __builtin_modf(f,d);       __builtin_modff(f,fp);      __builtin_modfl(f,l); __builtin_modff128(f,l);
 
-// NO__ERRNO: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE:#[0-9]+]]
-// NO__ERRNO: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
-// NO__ERRNO: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]
-// NO__ERRNO: declare fp128 @modff128(fp128 noundef, ptr noundef) [[NOT_READNONE]]
-// HAS_ERRNO: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE]]
-// HAS_ERRNO: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
-// HAS_ERRNO: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]
+// NO__ERRNO: declare { double, double } @llvm.modf.f64(double) [[READNONE_INTRINSIC]]
+// NO__ERRNO: declare { float, float } @llvm.modf.f32(float) [[READNONE_INTRINSIC]]
+// NO__ERRNO: declare { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80) [[READNONE_INTRINSIC]]
+// NO__ERRNO: declare fp128 @modff128(fp128 noundef, ptr noundef) [[NOT_READNONE:#[0-9]+]]
+// HAS_ERRNO: declare { double, double } @llvm.modf.f64(double) [[READNONE_INTRINSIC]]
+// HAS_ERRNO: declare { float, float } @llvm.modf.f32(float) [[READNONE_INTRINSIC]]
+// HAS_ERRNO: declare { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80) [[READNONE_INTRINSIC]]
 // HAS_ERRNO: declare fp128 @modff128(fp128 noundef, ptr noundef) [[NOT_READNONE]]
 
   __builtin_nan(c);        __builtin_nanf(c);       __builtin_nanl(c); __builtin_nanf128(c);
diff --git a/clang/test/CodeGen/aix-builtin-mapping.c b/clang/test/CodeGen/aix-builtin-mapping.c
index a79218c6f1d8b..cc1cc1a44f32c 100644
--- a/clang/test/CodeGen/aix-builtin-mapping.c
+++ b/clang/test/CodeGen/aix-builtin-mapping.c
@@ -17,6 +17,6 @@ int main()
   returnValue = __builtin_ldexpl(1.0L, 1);
 }
 
-// CHECK: %call = call double @modf(double noundef 1.000000e+00, ptr noundef %DummyLongDouble) #3
+// CHECK: %{{.+}} = call { double, double } @llvm.modf.f64(double 1.000000e+00)
 // CHECK: %{{.+}} = call { double, i32 } @llvm.frexp.f64.i32(double 0.000000e+00)
 // CHECK: %{{.+}} = call double @llvm.ldexp.f64.i32(double 1.000000e+00, i32 1)
diff --git a/clang/test/CodeGen/builtin-attributes.c b/clang/test/CodeGen/builtin-attributes.c
index e5b0faccfd23f..506b165fcf36e 100644
--- a/clang/test/CodeGen/builtin-attributes.c
+++ b/clang/test/CodeGen/builtin-attributes.c
@@ -24,6 +24,11 @@ char* f2(char* a, char* b) {
   return __builtin_strstr(a, b);
 }
 
+// Note: Use asm label to disable intrinsic lowering of modf.
+double modf(double x, double*) asm("modf");
+float modff(float x, float*) asm("modff");
+long double modfl(long double x, long double*) asm("modfl");
+
 // frexp is NOT readnone. It writes to its pointer argument.
 //
 // CHECK: f3
@@ -55,9 +60,9 @@ int f3(double x) {
   frexp(x, &e);
   frexpf(x, &e);
   frexpl(x, &e);
-  __builtin_modf(x, &e);
-  __builtin_modff(x, &e);
-  __builtin_modfl(x, &e);
+  modf(x, &e);
+  modff(x, &e);
+  modfl(x, &e);
   __builtin_remquo(x, x, &e);
   __builtin_remquof(x, x, &e);
   __builtin_remquol(x, x, &e);
diff --git a/clang/test/CodeGen/math-builtins-long.c b/clang/test/CodeGen/math-builtins-long.c
index 183349e0f0173..87e64a2eaa1c3 100644
--- a/clang/test/CodeGen/math-builtins-long.c
+++ b/clang/test/CodeGen/math-builtins-long.c
@@ -58,9 +58,9 @@ void foo(long double f, long double *l, int *i, const char *c) {
   // PPCF128: call fp128 @ldexpf128(fp128 noundef %{{.+}}, {{(signext)?.+}})
   __builtin_ldexpl(f,f);
 
-  // F80: call x86_fp80 @modfl(x86_fp80 noundef %{{.+}}, ptr noundef %{{.+}})
-  // PPC: call ppc_fp128 @modfl(ppc_fp128 noundef %{{.+}}, ptr noundef %{{.+}})
-  // X86F128: call fp128 @modfl(fp128 noundef %{{.+}}, ptr noundef %{{.+}})
+  // F80: call { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80 %{{.+}})
+  // PPC: call { ppc_fp128, ppc_fp128 } @llvm.modf.ppcf128(ppc_fp128 %{{.+}})
+  // X86F128: call { fp128, fp128 } @llvm.modf.f128(fp128 %{{.+}})
   // PPCF128: call fp128 @modff128(fp128 noundef %{{.+}}, ptr noundef %{{.+}})
   __builtin_modfl(f,l);
 
diff --git a/clang/test/CodeGen/math-libcalls.c b/clang/test/CodeGen/math-libcalls.c
index 14fdee77f4d78..ad297828f48ed 100644
--- a/clang/test/CodeGen/math-libcalls.c
+++ b/clang/test/CodeGen/math-libcalls.c
@@ -83,12 +83,12 @@ void foo(double *d, float f, float *fp, long double *l, int *i, const char *c) {
 
   modf(f,d);       modff(f,fp);      modfl(f,l);
 
-  // NO__ERRNO: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE]]
-  // NO__ERRNO: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
-  // NO__ERRNO: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]
-  // HAS_ERRNO: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE]]
-  // HAS_ERRNO: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
-  // HAS_ERRNO: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]
+  // NO__ERRNO: declare { double, double } @llvm.modf.f64(double) [[READNONE_INTRINSIC]]
+  // NO__ERRNO: declare { float, float } @llvm.modf.f32(float) [[READNONE_INTRINSIC]]
+  // NO__ERRNO: declare { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80) [[READNONE_INTRINSIC]]
+  // HAS_ERRNO: declare { double, double } @llvm.modf.f64(double) [[READNONE_INTRINSIC]]
+  // HAS_ERRNO: declare { float, float } @llvm.modf.f32(float) [[READNONE_INTRINSIC]]
+  // HAS_ERRNO: declare { x86_fp80, x86_fp80 } @llvm.modf.f80(x86_fp80) [[READNONE_INTRINSIC]]
   // HAS_MAYTRAP: declare double @modf(double noundef, ptr noundef) [[NOT_READNONE]]
   // HAS_MAYTRAP: declare float @modff(float noundef, ptr noundef) [[NOT_READNONE]]
   // HAS_MAYTRAP: declare x86_fp80 @modfl(x86_fp80 noundef, ptr noundef) [[NOT_READNONE]]

@MacDue MacDue merged commit fb397ab into main Mar 11, 2025
14 of 15 checks passed
@MacDue MacDue deleted the revert-127987-revert-126750-modf_builtin branch March 11, 2025 14:55
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backend:X86 clang:codegen IR generation bugs: mangling, exceptions, etc. clang Clang issues not falling into any other category skip-precommit-approval PR for CI feedback, not intended for review
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@MacDue @llvmbot