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Desugar complex element types for promoted complex division #168943

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Desugar complex element types for promoted complex division #168943

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Desugar complex element types for promoted complex division
zahiraam Nov 20, 2025
39e7c46
Addressed review comments
zahiraam Nov 21, 2025
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2 changes: 1 addition & 1 deletion clang/lib/CodeGen/CGExprComplex.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -320,7 +320,7 @@ class ComplexExprEmitter
QualType getPromotionType(FPOptionsOverride Features, QualType Ty,
bool IsComplexDivisor) {
if (auto *CT = Ty->getAs<ComplexType>()) {
QualType ElementType = CT->getElementType();
QualType ElementType = CT->getElementType().getCanonicalType();
bool IsFloatingType = ElementType->isFloatingType();
bool IsComplexRangePromoted = CGF.getLangOpts().getComplexRange() ==
LangOptions::ComplexRangeKind::CX_Promoted;
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2 changes: 1 addition & 1 deletion clang/lib/Sema/SemaExpr.cpp
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Expand Up @@ -10726,7 +10726,7 @@ static void DetectPrecisionLossInComplexDivision(Sema &S, QualType DivisorTy,
if (!CT)
return;

QualType ElementType = CT->getElementType();
QualType ElementType = CT->getElementType().getCanonicalType();
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@efriedma-quic efriedma-quic Nov 21, 2025

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Should we just do this in GetHigherPrecisionFPType()?

I guess it doesn't matter that much either way, since it only has two callers.

bool IsComplexRangePromoted = S.getLangOpts().getComplexRange() ==
LangOptions::ComplexRangeKind::CX_Promoted;
if (!ElementType->isFloatingType() || !IsComplexRangePromoted)
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52 changes: 52 additions & 0 deletions clang/test/CodeGen/promoted-complex-div.c
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Expand Up @@ -81,3 +81,55 @@ _Complex double divf(_Complex double a, _Complex double b) {

return a / b; // nopromotion-warning{{excess precision is requested but the target does not support excess precision which may result in observable differences in complex division behavior}}
}

// This test ensures that Clang does not crash when complex element types
// require desugaring under -complex-range=promoted. Previously, a sugared
// typedef element type (e.g., 'typedef double a') caused a crash during
// complex range evaluation in both Sema and CodeGen.
typedef double a;
_Complex double *b;
// CHECK-LABEL: define dso_local void @DivideByComplexZero
void DivideByComplexZero() {
// CHECK: fpext double {{.*}} to x86_fp80
// CHECK: fpext double {{.*}} to x86_fp80
// CHECK: fmul x86_fp80
// CHECK: fmul x86_fp80
// CHECK: fadd x86_fp80
// CHECK: fmul x86_fp80
// CHECK: fmul x86_fp80
// CHECK: fsub x86_fp80
// CHECK: fdiv x86_fp80
// CHECK: fdiv x86_fp80
// CHECK: fptrunc x86_fp80
// CHECK: fptrunc x86_fp80

// NOX87: call double @llvm.fabs.f64(double {{.*}})
// NOX87-NEXT: call double @llvm.fabs.f64(double {{.*}}
// NOX87-NEXT: fcmp ugt double {{.*}}, {{.*}}
// NOX87-NEXT: br i1 {{.*}}, label
// NOX87: abs_rhsr_greater_or_equal_abs_rhsi:
// NOX87-NEXT: fmul double
// NOX87-NEXT: fadd double
// NOX87-NEXT: fdiv double
// NOX87-NEXT: fmul double
// NOX87-NEXT: fsub double
// NOX87-NEXT: fdiv double
// NOX87-NEXT: br label {{.*}}
// NOX87: abs_rhsr_less_than_abs_rhsi:
// NOX87-NEXT: fmul double
// NOX87-NEXT: fadd double
// NOX87-NEXT: fdiv double
// NOX87-NEXT: fmul double
// NOX87-NEXT: fsub double
// NOX87-NEXT: fdiv double
// NOX87-NEXT: br label {{.*}}
// NOX87: complex_div:
// NOX87-NEXT: phi double
// NOX87-NEXT: phi double
// NOX87-NEXT: getelementptr inbounds nuw { double, double }, ptr {{.*}}, i32 0, i32 0
// NOX87-NEXT: getelementptr inbounds nuw { double, double }, ptr {{.*}}, i32 0, i32 1
// NOX87-NEXT: store double
// NOX87-NEXT: store double

*b /= 1.0iF * (a)0;
}