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[clang] Fix missing contract flag in sqrt intrinsic
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The fp options specified through pragma are already encoded in Expr.

This patch takes the same approach used by clang codegen to emit
fastmath flags for fadd insts, basically use RAII to set the
current fastmath flags in IRBuilder, which is then used to emit
sqrt intrinsic.

Fixes: #64653
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yxsamliu committed Aug 24, 2023
1 parent 7b27167 commit 63f0833
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Showing 2 changed files with 44 additions and 8 deletions.
2 changes: 1 addition & 1 deletion clang/lib/CodeGen/CGBuiltin.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -495,8 +495,8 @@ static Value *emitUnaryMaybeConstrainedFPBuiltin(CodeGenFunction &CGF,
unsigned ConstrainedIntrinsicID) {
llvm::Value *Src0 = CGF.EmitScalarExpr(E->getArg(0));

CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, E);
if (CGF.Builder.getIsFPConstrained()) {
CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, E);
Function *F = CGF.CGM.getIntrinsic(ConstrainedIntrinsicID, Src0->getType());
return CGF.Builder.CreateConstrainedFPCall(F, { Src0 });
} else {
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50 changes: 43 additions & 7 deletions clang/test/CodeGen/fp-contract-fast-pragma.cpp
Original file line number Diff line number Diff line change
@@ -1,19 +1,30 @@
// RUN: %clang_cc1 -O3 -triple %itanium_abi_triple -emit-llvm -o - %s | FileCheck %s
// RUN: %clang_cc1 -O3 -triple %itanium_abi_triple \
// RUN: -emit-llvm -o - %s \
// RUN: | FileCheck -check-prefixes=COMMON,CHECK %s
// RUN: %clang_cc1 -fexperimental-strict-floating-point \
// RUN: -ffp-exception-behavior=strict -O3 \
// RUN: -triple %itanium_abi_triple -emit-llvm -o - %s \
// RUN: | FileCheck -check-prefixes=COMMON,STRICT %s

// Is FP_CONTRACT honored in a simple case?
float fp_contract_1(float a, float b, float c) {
// CHECK: _Z13fp_contract_1fff
// COMMON: _Z13fp_contract_1fff
// CHECK: %[[M:.+]] = fmul contract float %a, %b
// CHECK-NEXT: fadd contract float %[[M]], %c
// STRICT: %[[M:.+]] = tail call contract float @llvm.experimental.constrained.fmul.f32(float %a, float %b, metadata !"round.tonearest", metadata !"fpexcept.strict")
// STRICT-NEXT: tail call contract float @llvm.experimental.constrained.fadd.f32(float %[[M]], float %c, metadata !"round.tonearest", metadata !"fpexcept.strict")

#pragma clang fp contract(fast)
return a * b + c;
}

// Is FP_CONTRACT state cleared on exiting compound statements?
float fp_contract_2(float a, float b, float c) {
// CHECK: _Z13fp_contract_2fff
// COMMON: _Z13fp_contract_2fff
// CHECK: %[[M:.+]] = fmul float %a, %b
// CHECK-NEXT: fadd float %[[M]], %c
// STRICT: %[[M:.+]] = tail call float @llvm.experimental.constrained.fmul.f32(float %a, float %b, metadata !"round.tonearest", metadata !"fpexcept.strict")
// STRICT-NEXT: tail call float @llvm.experimental.constrained.fadd.f32(float %[[M]], float %c, metadata !"round.tonearest", metadata !"fpexcept.strict")
{
#pragma clang fp contract(fast)
}
Expand All @@ -31,9 +42,11 @@ T template_muladd(T a, T b, T c) {
}

float fp_contract_3(float a, float b, float c) {
// CHECK: _Z13fp_contract_3fff
// COMMON: _Z13fp_contract_3fff
// CHECK: %[[M:.+]] = fmul contract float %a, %b
// CHECK-NEXT: fadd contract float %[[M]], %c
// STRICT: %[[M:.+]] = tail call contract float @llvm.experimental.constrained.fmul.f32(float %a, float %b, metadata !"round.tonearest", metadata !"fpexcept.strict")
// STRICT-NEXT: tail call contract float @llvm.experimental.constrained.fadd.f32(float %[[M]], float %c, metadata !"round.tonearest", metadata !"fpexcept.strict")
return template_muladd<float>(a, b, c);
}

Expand All @@ -46,24 +59,47 @@ class fp_contract_4 {
};

template class fp_contract_4<int>;
// CHECK: _ZN13fp_contract_4IiE6methodEfff
// COMMON: _ZN13fp_contract_4IiE6methodEfff
// CHECK: %[[M:.+]] = fmul contract float %a, %b
// CHECK-NEXT: fadd contract float %[[M]], %c
// STRICT: %[[M:.+]] = tail call contract float @llvm.experimental.constrained.fmul.f32(float %a, float %b, metadata !"round.tonearest", metadata !"fpexcept.strict")
// STRICT-NEXT: tail call contract float @llvm.experimental.constrained.fadd.f32(float %[[M]], float %c, metadata !"round.tonearest", metadata !"fpexcept.strict")

// Check file-scoped FP_CONTRACT
#pragma clang fp contract(fast)
float fp_contract_5(float a, float b, float c) {
// CHECK: _Z13fp_contract_5fff
// COMMON: _Z13fp_contract_5fff
// CHECK: %[[M:.+]] = fmul contract float %a, %b
// CHECK-NEXT: fadd contract float %[[M]], %c
// STRICT: %[[M:.+]] = tail call contract float @llvm.experimental.constrained.fmul.f32(float %a, float %b, metadata !"round.tonearest", metadata !"fpexcept.strict")
// STRICT-NEXT: tail call contract float @llvm.experimental.constrained.fadd.f32(float %[[M]], float %c, metadata !"round.tonearest", metadata !"fpexcept.strict")
return a * b + c;
}

// Verify that we can handle multiple flags on the same pragma
#pragma clang fp contract(fast) contract(off)
float fp_contract_6(float a, float b, float c) {
// CHECK: _Z13fp_contract_6fff
// COMMON: _Z13fp_contract_6fff
// CHECK: %[[M:.+]] = fmul float %a, %b
// CHECK-NEXT: fadd float %[[M]], %c
// STRICT: %[[M:.+]] = tail call float @llvm.experimental.constrained.fmul.f32(float %a, float %b, metadata !"round.tonearest", metadata !"fpexcept.strict")
// STRICT-NEXT: tail call float @llvm.experimental.constrained.fadd.f32(float %[[M]], float %c, metadata !"round.tonearest", metadata !"fpexcept.strict")
return a * b + c;
}


#pragma clang fp contract(fast)
float fp_contract_7(float a) {
// COMMON: _Z13fp_contract_7f
// CHECK: tail call contract float @llvm.sqrt.f32(float %a)
// STRICT: tail call contract float @llvm.experimental.constrained.sqrt.f32(float %a, metadata !"round.tonearest", metadata !"fpexcept.strict")
return __builtin_sqrtf(a);
}

float fp_contract_8(float a) {
// COMMON: _Z13fp_contract_8f
// CHECK: tail call float @llvm.sqrt.f32(float %a)
// STRICT: tail call float @llvm.experimental.constrained.sqrt.f32(float %a, metadata !"round.tonearest", metadata !"fpexcept.strict")
#pragma clang fp contract(off)
return __builtin_sqrtf(a);
}

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