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[Clang] Fix clang to emit llvm-ir for fadd/fsub atomics #162679

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[Clang] Fix clang to emit llvm-ir for fadd/fsub atomics #162679

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e654aa7
[LLVM] Fix clang to emit llvm-ir for fadd/fsub atomics
Amichaxx Oct 6, 2025
653b974
clang format
Amichaxx Oct 9, 2025
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21 changes: 16 additions & 5 deletions clang/lib/CodeGen/CGExprScalar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3847,7 +3847,16 @@ LValue ScalarExprEmitter::EmitCompoundAssignLValue(
llvm::PHINode *atomicPHI = nullptr;
if (const AtomicType *atomicTy = LHSTy->getAs<AtomicType>()) {
QualType type = atomicTy->getValueType();
if (!type->isBooleanType() && type->isIntegerType() &&
const bool isFloat = type->isFloatingType();
const bool isInteger = type->isIntegerType();

bool isPowerOfTwo = false;
if (isFloat || isInteger) {
llvm::Type *IRTy = CGF.ConvertType(type);
uint64_t StoreBits = CGF.CGM.getDataLayout().getTypeStoreSizeInBits(IRTy);
isPowerOfTwo = llvm::isPowerOf2_64(StoreBits);
}
if (!type->isBooleanType() && (isInteger || isFloat) && isPowerOfTwo &&
!(type->isUnsignedIntegerType() &&
CGF.SanOpts.has(SanitizerKind::UnsignedIntegerOverflow)) &&
CGF.getLangOpts().getSignedOverflowBehavior() !=
Expand All @@ -3862,12 +3871,14 @@ LValue ScalarExprEmitter::EmitCompoundAssignLValue(
case BO_ShrAssign:
break;
case BO_AddAssign:
AtomicOp = llvm::AtomicRMWInst::Add;
Op = llvm::Instruction::Add;
AtomicOp =
isFloat ? llvm::AtomicRMWInst::FAdd : llvm::AtomicRMWInst::Add;
Op = isFloat ? llvm::Instruction::FAdd : llvm::Instruction::Add;
break;
case BO_SubAssign:
AtomicOp = llvm::AtomicRMWInst::Sub;
Op = llvm::Instruction::Sub;
AtomicOp =
isFloat ? llvm::AtomicRMWInst::FSub : llvm::AtomicRMWInst::Sub;
Op = isFloat ? llvm::Instruction::FSub : llvm::Instruction::Sub;
break;
case BO_AndAssign:
AtomicOp = llvm::AtomicRMWInst::And;
Expand Down
61 changes: 61 additions & 0 deletions clang/test/CodeGen/aarch64-lsfe-atomics.c
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@@ -0,0 +1,61 @@
// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 6
// RUN: %clang_cc1 %s -emit-llvm -o - -triple=aarch64-linux-gnu | FileCheck %s --check-prefix=CHECK-LLVM

_Atomic(float) f;
_Atomic(double) d;

// CHECK-LLVM-LABEL: define dso_local void @test_float_add(
// CHECK-LLVM-SAME: float noundef [[VAL:%.*]]) #[[ATTR0:[0-9]+]] {
// CHECK-LLVM-NEXT: [[ENTRY:.*:]]
// CHECK-LLVM-NEXT: [[VAL_ADDR:%.*]] = alloca float, align 4
// CHECK-LLVM-NEXT: store float [[VAL]], ptr [[VAL_ADDR]], align 4
// CHECK-LLVM-NEXT: [[TMP0:%.*]] = load float, ptr [[VAL_ADDR]], align 4
// CHECK-LLVM-NEXT: [[TMP1:%.*]] = atomicrmw fadd ptr @f, float [[TMP0]] seq_cst, align 4
// CHECK-LLVM-NEXT: [[TMP2:%.*]] = fadd float [[TMP1]], [[TMP0]]
// CHECK-LLVM-NEXT: ret void
//
void test_float_add(float val) {
f += val;
}

// CHECK-LLVM-LABEL: define dso_local void @test_double_add(
// CHECK-LLVM-SAME: double noundef [[VAL:%.*]]) #[[ATTR0]] {
// CHECK-LLVM-NEXT: [[ENTRY:.*:]]
// CHECK-LLVM-NEXT: [[VAL_ADDR:%.*]] = alloca double, align 8
// CHECK-LLVM-NEXT: store double [[VAL]], ptr [[VAL_ADDR]], align 8
// CHECK-LLVM-NEXT: [[TMP0:%.*]] = load double, ptr [[VAL_ADDR]], align 8
// CHECK-LLVM-NEXT: [[TMP1:%.*]] = atomicrmw fadd ptr @d, double [[TMP0]] seq_cst, align 8
// CHECK-LLVM-NEXT: [[TMP2:%.*]] = fadd double [[TMP1]], [[TMP0]]
// CHECK-LLVM-NEXT: ret void
//
void test_double_add(double val) {
d += val;
}

// CHECK-LLVM-LABEL: define dso_local void @test_float_sub(
// CHECK-LLVM-SAME: float noundef [[VAL:%.*]]) #[[ATTR0]] {
// CHECK-LLVM-NEXT: [[ENTRY:.*:]]
// CHECK-LLVM-NEXT: [[VAL_ADDR:%.*]] = alloca float, align 4
// CHECK-LLVM-NEXT: store float [[VAL]], ptr [[VAL_ADDR]], align 4
// CHECK-LLVM-NEXT: [[TMP0:%.*]] = load float, ptr [[VAL_ADDR]], align 4
// CHECK-LLVM-NEXT: [[TMP1:%.*]] = atomicrmw fsub ptr @f, float [[TMP0]] seq_cst, align 4
// CHECK-LLVM-NEXT: [[TMP2:%.*]] = fsub float [[TMP1]], [[TMP0]]
// CHECK-LLVM-NEXT: ret void
//
void test_float_sub(float val) {
f -= val;
}

// CHECK-LLVM-LABEL: define dso_local void @test_double_sub(
// CHECK-LLVM-SAME: double noundef [[VAL:%.*]]) #[[ATTR0]] {
// CHECK-LLVM-NEXT: [[ENTRY:.*:]]
// CHECK-LLVM-NEXT: [[VAL_ADDR:%.*]] = alloca double, align 8
// CHECK-LLVM-NEXT: store double [[VAL]], ptr [[VAL_ADDR]], align 8
// CHECK-LLVM-NEXT: [[TMP0:%.*]] = load double, ptr [[VAL_ADDR]], align 8
// CHECK-LLVM-NEXT: [[TMP1:%.*]] = atomicrmw fsub ptr @d, double [[TMP0]] seq_cst, align 8
// CHECK-LLVM-NEXT: [[TMP2:%.*]] = fsub double [[TMP1]], [[TMP0]]
// CHECK-LLVM-NEXT: ret void
//
void test_double_sub(double val){
d -= val;
}