================
@@ -1101,3 +1111,236 @@ std::optional<LValue>
CGHLSLRuntime::emitResourceArraySubscriptExpr(
}
return CGF.MakeAddrLValue(TmpVar, ResultTy, AlignmentSource::Decl);
}
+
+std::optional<LValue> CGHLSLRuntime::emitBufferArraySubscriptExpr(
+ const ArraySubscriptExpr *E, CodeGenFunction &CGF,
+ llvm::function_ref<llvm::Value *(bool Promote)> EmitIdxAfterBase) {
+ // Find the element type to index by first padding the element type per HLSL
+ // buffer rules, and then padding out to a 16-byte register boundary if
+ // necessary.
+ llvm::Type *LayoutTy =
+ HLSLBufferLayoutBuilder(CGF.CGM).layOutType(E->getType());
+ uint64_t LayoutSizeInBits =
+ CGM.getDataLayout().getTypeSizeInBits(LayoutTy).getFixedValue();
+ CharUnits ElementSize = CharUnits::fromQuantity(LayoutSizeInBits / 8);
+ CharUnits RowAlignedSize = ElementSize.alignTo(CharUnits::fromQuantity(16));
+ if (RowAlignedSize > ElementSize) {
+ llvm::Type *Padding = CGM.getTargetCodeGenInfo().getHLSLPadding(
+ CGM, RowAlignedSize - ElementSize);
+ assert(Padding && "No padding type for target?");
+ LayoutTy = llvm::StructType::get(CGF.getLLVMContext(), {LayoutTy, Padding},
+ /*isPacked=*/true);
+ }
+
+ // If the layout type doesn't introduce any padding, we don't need to do
+ // anything special.
+ llvm::Type *OrigTy = CGF.CGM.getTypes().ConvertTypeForMem(E->getType());
+ if (LayoutTy == OrigTy)
+ return std::nullopt;
+
+ LValueBaseInfo EltBaseInfo;
+ TBAAAccessInfo EltTBAAInfo;
+ Address Addr =
+ CGF.EmitPointerWithAlignment(E->getBase(), &EltBaseInfo, &EltTBAAInfo);
+ llvm::Value *Idx = EmitIdxAfterBase(/*Promote*/ true);
+
+ // Index into the object as-if we have an array of the padded element type,
+ // and then dereference the element itself to avoid reading padding that may
+ // be past the end of the in-memory object.
+ SmallVector<llvm::Value *, 2> Indices;
+ Indices.push_back(Idx);
+ Indices.push_back(llvm::ConstantInt::get(Idx->getType(), 0));
+
+ llvm::Value *GEP = CGF.Builder.CreateGEP(LayoutTy, Addr.emitRawPointer(CGF),
+ Indices, "cbufferidx");
+ Addr = Address(GEP, Addr.getElementType(), RowAlignedSize, KnownNonNull);
----------------
s-perron wrote:
I was trying the example below, and I'm getting an error when compiling for
spir-v. It complains that the GEP is not valid. This is coming from the
verifier. It does not fail for DXIL. Do you know anything about this?
```
Invalid indices for GEP pointer type!
%cbufferidx = getelementptr <{ <3 x float>, target("spirv.Padding", 4) }>,
ptr addrspace(12) @myArray, i64 %idxprom, i64 0
fatal error: error in backend: Broken module found, compilation aborted!
```
```
cbuffer MyCBuffer : register(b0)
{
// An array of 3 elements. This should be represented in IR
// as a struct containing an array of 2 elements and a final
// separate element to handle cbuffer padding rules.
float3 myArray[3];
};
RWStructuredBuffer<float3> output : register(u0);
[numthreads(8, 1, 1)]
void main(uint3 dispatchThreadID : SV_DispatchThreadID)
{
// Access the array with a variable index to ensure
// the compiler generates GEPs for indexing.
uint index = dispatchThreadID.x % 3;
output[dispatchThreadID.x] = myArray[index];
}
```
https://github.com/llvm/llvm-project/pull/167404
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