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[SPIRV] Handle ptrcast between array and vector types #166418

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Nov 12, 2025
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[SPIRV] Handle ptrcast between array and vector types #166418

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3abe11e
[SPIRV] Handle ptrcast between array and vector types
s-perron Oct 30, 2025
3c0e197
Changes from code review.
s-perron Nov 8, 2025
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80 changes: 80 additions & 0 deletions llvm/lib/Target/SPIRV/SPIRVLegalizePointerCast.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,81 @@ class SPIRVLegalizePointerCast : public FunctionPass {
return LI;
}

// Loads elements from an array and constructs a vector.
Value *loadVectorFromArray(IRBuilder<> &B, FixedVectorType *TargetType,
Value *Source) {
// Load each element of the array.
SmallVector<Value *, 4> LoadedElements;
for (unsigned i = 0; i < TargetType->getNumElements(); ++i) {
// Create a GEP to access the i-th element of the array.
SmallVector<Type *, 2> Types = {Source->getType(), Source->getType()};
SmallVector<Value *, 4> Args;
Args.push_back(B.getInt1(false));
Args.push_back(Source);
Args.push_back(B.getInt32(0));
Args.push_back(ConstantInt::get(B.getInt32Ty(), i));
auto *ElementPtr = B.CreateIntrinsic(Intrinsic::spv_gep, {Types}, {Args});
GR->buildAssignPtr(B, TargetType->getElementType(), ElementPtr);

// Load the value from the element pointer.
Value *Load = B.CreateLoad(TargetType->getElementType(), ElementPtr);
buildAssignType(B, TargetType->getElementType(), Load);
LoadedElements.push_back(Load);
}

// Build the vector from the loaded elements.
Value *NewVector = PoisonValue::get(TargetType);
buildAssignType(B, TargetType, NewVector);

for (unsigned i = 0; i < TargetType->getNumElements(); ++i) {
Value *Index = B.getInt32(i);
SmallVector<Type *, 4> Types = {TargetType, TargetType,
TargetType->getElementType(),
Index->getType()};
SmallVector<Value *> Args = {NewVector, LoadedElements[i], Index};
NewVector = B.CreateIntrinsic(Intrinsic::spv_insertelt, {Types}, {Args});
buildAssignType(B, TargetType, NewVector);
}
return NewVector;
}

// Stores elements from a vector into an array.
void storeArrayFromVector(IRBuilder<> &B, Value *SrcVector,
Value *DstArrayPtr, ArrayType *ArrTy,
Align Alignment) {
auto *VecTy = cast<FixedVectorType>(SrcVector->getType());

// Ensure the element types of the array and vector are the same.
assert(VecTy->getElementType() == ArrTy->getElementType() &&
"Element types of array and vector must be the same.");

for (unsigned i = 0; i < VecTy->getNumElements(); ++i) {
// Create a GEP to access the i-th element of the array.
SmallVector<Type *, 2> Types = {DstArrayPtr->getType(),
DstArrayPtr->getType()};
SmallVector<Value *, 4> Args;
Args.push_back(B.getInt1(false));
Args.push_back(DstArrayPtr);
Args.push_back(B.getInt32(0));
Args.push_back(ConstantInt::get(B.getInt32Ty(), i));
auto *ElementPtr = B.CreateIntrinsic(Intrinsic::spv_gep, {Types}, {Args});
GR->buildAssignPtr(B, ArrTy->getElementType(), ElementPtr);

// Extract the element from the vector and store it.
Value *Index = B.getInt32(i);
SmallVector<Type *, 3> EltTypes = {VecTy->getElementType(), VecTy,
Index->getType()};
SmallVector<Value *, 2> EltArgs = {SrcVector, Index};
Value *Element =
B.CreateIntrinsic(Intrinsic::spv_extractelt, {EltTypes}, {EltArgs});
buildAssignType(B, VecTy->getElementType(), Element);

Types = {Element->getType(), ElementPtr->getType()};
Args = {Element, ElementPtr, B.getInt16(2), B.getInt8(Alignment.value())};
B.CreateIntrinsic(Intrinsic::spv_store, {Types}, {Args});
}
}

// Replaces the load instruction to get rid of the ptrcast used as source
// operand.
void transformLoad(IRBuilder<> &B, LoadInst *LI, Value *CastedOperand,
Expand Down Expand Up @@ -154,6 +229,8 @@ class SPIRVLegalizePointerCast : public FunctionPass {
// - float v = s.m;
else if (SST && SST->getTypeAtIndex(0u) == ToTy)
Output = loadFirstValueFromAggregate(B, ToTy, OriginalOperand, LI);
else if (SAT && DVT && SAT->getElementType() == DVT->getElementType())
Output = loadVectorFromArray(B, DVT, OriginalOperand);
else
llvm_unreachable("Unimplemented implicit down-cast from load.");

Expand Down Expand Up @@ -288,6 +365,7 @@ class SPIRVLegalizePointerCast : public FunctionPass {
auto *S_VT = dyn_cast<FixedVectorType>(FromTy);
auto *D_ST = dyn_cast<StructType>(ToTy);
auto *D_VT = dyn_cast<FixedVectorType>(ToTy);
auto *D_AT = dyn_cast<ArrayType>(ToTy);

B.SetInsertPoint(BadStore);
if (D_ST && isTypeFirstElementAggregate(FromTy, D_ST))
Expand All @@ -296,6 +374,8 @@ class SPIRVLegalizePointerCast : public FunctionPass {
storeVectorFromVector(B, Src, Dst, Alignment);
else if (D_VT && !S_VT && FromTy == D_VT->getElementType())
storeToFirstValueAggregate(B, Src, Dst, D_VT, Alignment);
else if (D_AT && S_VT && S_VT->getElementType() == D_AT->getElementType())
storeArrayFromVector(B, Src, Dst, D_AT, Alignment);
else
llvm_unreachable("Unsupported ptrcast use in store. Please fix.");

Expand Down
54 changes: 54 additions & 0 deletions llvm/test/CodeGen/SPIRV/pointers/load-store-vec-from-array.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,54 @@
; RUN: llc -O0 -verify-machineinstrs -mtriple=spirv-unknown-vulkan %s -o - | FileCheck %s
; RUN: %if spirv-tools %{ llc -O0 -verify-machineinstrs -mtriple=spirv-unknown-vulkan %s -o - -filetype=obj | spirv-val %}

; CHECK-DAG: [[FLOAT:%[0-9]+]] = OpTypeFloat 32
; CHECK-DAG: [[VEC4FLOAT:%[0-9]+]] = OpTypeVector [[FLOAT]] 4
; CHECK-DAG: [[UINT_TYPE:%[0-9]+]] = OpTypeInt 32 0
; CHECK-DAG: [[UINT4:%[0-9]+]] = OpConstant [[UINT_TYPE]] 4
; CHECK-DAG: [[ARRAY4FLOAT:%[0-9]+]] = OpTypeArray [[FLOAT]] [[UINT4]]
; CHECK-DAG: [[PTR_ARRAY4FLOAT:%[0-9]+]] = OpTypePointer Private [[ARRAY4FLOAT]]
; CHECK-DAG: [[G_IN:%[0-9]+]] = OpVariable [[PTR_ARRAY4FLOAT]] Private
; CHECK-DAG: [[G_OUT:%[0-9]+]] = OpVariable [[PTR_ARRAY4FLOAT]] Private
; CHECK-DAG: [[UINT0:%[0-9]+]] = OpConstant [[UINT_TYPE]] 0
; CHECK-DAG: [[UINT1:%[0-9]+]] = OpConstant [[UINT_TYPE]] 1
; CHECK-DAG: [[UINT2:%[0-9]+]] = OpConstant [[UINT_TYPE]] 2
; CHECK-DAG: [[UINT3:%[0-9]+]] = OpConstant [[UINT_TYPE]] 3
; CHECK-DAG: [[PTR_FLOAT:%[0-9]+]] = OpTypePointer Private [[FLOAT]]
; CHECK-DAG: [[UNDEF_VEC:%[0-9]+]] = OpUndef [[VEC4FLOAT]]

@G_in = internal addrspace(10) global [4 x float] zeroinitializer
@G_out = internal addrspace(10) global [4 x float] zeroinitializer

define spir_func void @main() {
entry:
; CHECK: [[GEP0:%[0-9]+]] = OpAccessChain [[PTR_FLOAT]] [[G_IN]] [[UINT0]]
; CHECK-NEXT: [[LOAD0:%[0-9]+]] = OpLoad [[FLOAT]] [[GEP0]]
; CHECK-NEXT: [[GEP1:%[0-9]+]] = OpAccessChain [[PTR_FLOAT]] [[G_IN]] [[UINT1]]
; CHECK-NEXT: [[LOAD1:%[0-9]+]] = OpLoad [[FLOAT]] [[GEP1]]
; CHECK-NEXT: [[GEP2:%[0-9]+]] = OpAccessChain [[PTR_FLOAT]] [[G_IN]] [[UINT2]]
; CHECK-NEXT: [[LOAD2:%[0-9]+]] = OpLoad [[FLOAT]] [[GEP2]]
; CHECK-NEXT: [[GEP3:%[0-9]+]] = OpAccessChain [[PTR_FLOAT]] [[G_IN]] [[UINT3]]
; CHECK-NEXT: [[LOAD3:%[0-9]+]] = OpLoad [[FLOAT]] [[GEP3]]
; CHECK-NEXT: [[VEC_INSERT0:%[0-9]+]] = OpCompositeInsert [[VEC4FLOAT]] [[LOAD0]] [[UNDEF_VEC]] 0
; CHECK-NEXT: [[VEC_INSERT1:%[0-9]+]] = OpCompositeInsert [[VEC4FLOAT]] [[LOAD1]] [[VEC_INSERT0]] 1
; CHECK-NEXT: [[VEC_INSERT2:%[0-9]+]] = OpCompositeInsert [[VEC4FLOAT]] [[LOAD2]] [[VEC_INSERT1]] 2
; CHECK-NEXT: [[VEC:%[0-9]+]] = OpCompositeInsert [[VEC4FLOAT]] [[LOAD3]] [[VEC_INSERT2]] 3
%0 = load <4 x float>, ptr addrspace(10) @G_in, align 64

; CHECK-NEXT: [[GEP_OUT0:%[0-9]+]] = OpAccessChain [[PTR_FLOAT]] [[G_OUT]] [[UINT0]]
; CHECK-NEXT: [[VEC_EXTRACT0:%[0-9]+]] = OpCompositeExtract [[FLOAT]] [[VEC]] 0
; CHECK-NEXT: OpStore [[GEP_OUT0]] [[VEC_EXTRACT0]]
; CHECK-NEXT: [[GEP_OUT1:%[0-9]+]] = OpAccessChain [[PTR_FLOAT]] [[G_OUT]] [[UINT1]]
; CHECK-NEXT: [[VEC_EXTRACT1:%[0-9]+]] = OpCompositeExtract [[FLOAT]] [[VEC]] 1
; CHECK-NEXT: OpStore [[GEP_OUT1]] [[VEC_EXTRACT1]]
; CHECK-NEXT: [[GEP_OUT2:%[0-9]+]] = OpAccessChain [[PTR_FLOAT]] [[G_OUT]] [[UINT2]]
; CHECK-NEXT: [[VEC_EXTRACT2:%[0-9]+]] = OpCompositeExtract [[FLOAT]] [[VEC]] 2
; CHECK-NEXT: OpStore [[GEP_OUT2]] [[VEC_EXTRACT2]]
; CHECK-NEXT: [[GEP_OUT3:%[0-9]+]] = OpAccessChain [[PTR_FLOAT]] [[G_OUT]] [[UINT3]]
; CHECK-NEXT: [[VEC_EXTRACT3:%[0-9]+]] = OpCompositeExtract [[FLOAT]] [[VEC]] 3
; CHECK-NEXT: OpStore [[GEP_OUT3]] [[VEC_EXTRACT3]]
store <4 x float> %0, ptr addrspace(10) @G_out, align 64

; CHECK-NEXT: OpReturn
ret void
}