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[NFC][hlsl][Sema] Simplify CBuffer Legacy Size Calculation Control Flow #127921

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Merged
merged 1 commit into from
Feb 20, 2025
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[NFC][hlsl][Sema] Simplify CBuffer Legacy Size Calculation Control Flow #127921

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32 changes: 19 additions & 13 deletions clang/lib/Sema/SemaHLSL.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -176,9 +176,9 @@ Decl *SemaHLSL::ActOnStartBuffer(Scope *BufferScope, bool CBuffer,
// https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-packing-rules
static unsigned calculateLegacyCbufferSize(const ASTContext &Context,
QualType T) {
unsigned Size = 0;
constexpr unsigned CBufferAlign = 16;
if (const RecordType *RT = T->getAs<RecordType>()) {
unsigned Size = 0;
const RecordDecl *RD = RT->getDecl();
for (const FieldDecl *Field : RD->fields()) {
QualType Ty = Field->getType();
Expand All @@ -191,22 +191,28 @@ static unsigned calculateLegacyCbufferSize(const ASTContext &Context,
Size = llvm::alignTo(Size, FieldAlign);
Size += FieldSize;
}
} else if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
if (unsigned ElementCount = AT->getSize().getZExtValue()) {
unsigned ElementSize =
calculateLegacyCbufferSize(Context, AT->getElementType());
unsigned AlignedElementSize = llvm::alignTo(ElementSize, CBufferAlign);
Size = AlignedElementSize * (ElementCount - 1) + ElementSize;
}
} else if (const VectorType *VT = T->getAs<VectorType>()) {
return Size;
}

if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
unsigned ElementCount = AT->getSize().getZExtValue();
if (ElementCount == 0)
return 0;

unsigned ElementSize =
calculateLegacyCbufferSize(Context, AT->getElementType());
unsigned AlignedElementSize = llvm::alignTo(ElementSize, CBufferAlign);
return AlignedElementSize * (ElementCount - 1) + ElementSize;
}

if (const VectorType *VT = T->getAs<VectorType>()) {
unsigned ElementCount = VT->getNumElements();
unsigned ElementSize =
calculateLegacyCbufferSize(Context, VT->getElementType());
Size = ElementSize * ElementCount;
} else {
Size = Context.getTypeSize(T) / 8;
return ElementSize * ElementCount;
}
return Size;

return Context.getTypeSize(T) / 8;
}

// Validate packoffset:
Expand Down