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[HLSL] Add an lvalue to rvalue cast when appropriate for HLSLElementwiseCast and HLSLAggregateSplatCast #163828

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Merged
merged 1 commit into from
Oct 16, 2025
Merged

[HLSL] Add an lvalue to rvalue cast when appropriate for HLSLElementwiseCast and HLSLAggregateSplatCast #163828

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3 changes: 3 additions & 0 deletions clang/lib/Sema/SemaCast.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2927,6 +2927,8 @@ bool CastOperation::CheckHLSLCStyleCast(CheckedConversionKind CCK) {
SrcExpr = Self.ImpCastExprToType(
SrcExpr.get(), Self.Context.getArrayParameterType(SrcTy),
CK_HLSLArrayRValue, VK_PRValue, nullptr, CCK);
else
SrcExpr = Self.DefaultLvalueConversion(SrcExpr.get());
Kind = CK_HLSLElementwiseCast;
return true;
}
Expand All @@ -2935,6 +2937,7 @@ bool CastOperation::CheckHLSLCStyleCast(CheckedConversionKind CCK) {
// If the relative order of this and the HLSLElementWise cast checks
// are changed, it might change which cast handles what in a few cases
if (Self.HLSL().CanPerformAggregateSplatCast(SrcExpr.get(), DestType)) {
SrcExpr = Self.DefaultLvalueConversion(SrcExpr.get());
const VectorType *VT = SrcTy->getAs<VectorType>();
// change splat from vec1 case to splat from scalar
if (VT && VT->getNumElements() == 1)
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7 changes: 4 additions & 3 deletions clang/test/SemaHLSL/Language/AggregateSplatCasts.hlsl
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Expand Up @@ -3,8 +3,9 @@
// splat from vec1 to vec
// CHECK-LABEL: call1
// CHECK: CStyleCastExpr {{.*}} 'int3':'vector<int, 3>' <HLSLAggregateSplatCast>
// CHECK-NEXT: ImplicitCastExpr {{.*}} 'int' lvalue <FloatingToIntegral> part_of_explicit_cast
// CHECK-NEXT: ImplicitCastExpr {{.*}} 'float' lvalue <HLSLVectorTruncation> part_of_explicit_cast
// CHECK-NEXT: ImplicitCastExpr {{.*}} 'int' <FloatingToIntegral> part_of_explicit_cast
// CHECK-NEXT: ImplicitCastExpr {{.*}} 'float' <HLSLVectorTruncation> part_of_explicit_cast
// CHECK-NEXT: ImplicitCastExpr {{.*}} 'float1':'vector<float, 1>' <LValueToRValue> part_of_explicit_cast
// CHECK-NEXT: DeclRefExpr {{.*}} 'float1':'vector<float, 1>' lvalue Var {{.*}} 'A' 'float1':'vector<float, 1>'
export void call1() {
float1 A = {1.0};
Expand All @@ -21,7 +22,7 @@ struct S {
// splat from scalar to aggregate
// CHECK-LABEL: call2
// CHECK: CStyleCastExpr {{.*}} 'S' <HLSLAggregateSplatCast>
// CHECK-NEXt: IntegerLiteral {{.*}} 'int' 5
// CHECK-NEXT: IntegerLiteral {{.*}} 'int' 5
export void call2() {
S s = (S)5;
}
24 changes: 24 additions & 0 deletions clang/test/SemaHLSL/Language/ElementwiseCasts.hlsl
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Expand Up @@ -21,3 +21,27 @@ export void call2() {
float B[1] = {1.0};
B = (float[1])A;
}

struct S {
int A;
float F;
};

// cast from a struct
// CHECK-LABEL: call3
// CHECK: CStyleCastExpr {{.*}} 'int[2]' <HLSLElementwiseCast>
// CHECK-NEXT: DeclRefExpr {{.*}} 'S' lvalue Var {{.*}} 'SS' 'S'
export void call3() {
S SS = {1,1.0};
int A[2] = (int[2])SS;
}

// cast from a vector
// CHECK-LABEL: call4
// CHECK: CStyleCastExpr {{.*}} 'float[3]' <HLSLElementwiseCast>
// CHECK-NEXT: ImplicitCastExpr {{.*}} 'int3':'vector<int, 3>' <LValueToRValue> part_of_explicit_cast
// CHECK-NEXT: DeclRefExpr {{.*}} 'int3':'vector<int, 3>' lvalue Var {{.*}} 'A' 'int3'
export void call4() {
int3 A = {1,2,3};
float B[3] = (float[3])A;
}