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-rw-r--r--llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp8
-rw-r--r--llvm/lib/Target/SPIRV/SPIRVLegalizePointerCast.cpp9
-rw-r--r--llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp3
-rw-r--r--llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp61
4 files changed, 51 insertions, 30 deletions
diff --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index 3fea21e..3f0424f 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -3151,6 +3151,14 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
return selectInsertElt(ResVReg, ResType, I);
case Intrinsic::spv_gep:
return selectGEP(ResVReg, ResType, I);
+ case Intrinsic::spv_bitcast: {
+ Register OpReg = I.getOperand(2).getReg();
+ SPIRVType *OpType =
+ OpReg.isValid() ? GR.getSPIRVTypeForVReg(OpReg) : nullptr;
+ if (!GR.isBitcastCompatible(ResType, OpType))
+ report_fatal_error("incompatible result and operand types in a bitcast");
+ return selectOpWithSrcs(ResVReg, ResType, I, {OpReg}, SPIRV::OpBitcast);
+ }
case Intrinsic::spv_unref_global:
case Intrinsic::spv_init_global: {
MachineInstr *MI = MRI->getVRegDef(I.getOperand(1).getReg());
diff --git a/llvm/lib/Target/SPIRV/SPIRVLegalizePointerCast.cpp b/llvm/lib/Target/SPIRV/SPIRVLegalizePointerCast.cpp
index 6e444c9..65dffc7 100644
--- a/llvm/lib/Target/SPIRV/SPIRVLegalizePointerCast.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVLegalizePointerCast.cpp
@@ -73,16 +73,23 @@ class SPIRVLegalizePointerCast : public FunctionPass {
// Returns the loaded value.
Value *loadVectorFromVector(IRBuilder<> &B, FixedVectorType *SourceType,
FixedVectorType *TargetType, Value *Source) {
- assert(TargetType->getNumElements() <= SourceType->getNumElements());
LoadInst *NewLoad = B.CreateLoad(SourceType, Source);
buildAssignType(B, SourceType, NewLoad);
Value *AssignValue = NewLoad;
if (TargetType->getElementType() != SourceType->getElementType()) {
+ const DataLayout &DL = B.GetInsertBlock()->getModule()->getDataLayout();
+ [[maybe_unused]] TypeSize TargetTypeSize =
+ DL.getTypeSizeInBits(TargetType);
+ [[maybe_unused]] TypeSize SourceTypeSize =
+ DL.getTypeSizeInBits(SourceType);
+ assert(TargetTypeSize == SourceTypeSize);
AssignValue = B.CreateIntrinsic(Intrinsic::spv_bitcast,
{TargetType, SourceType}, {NewLoad});
buildAssignType(B, TargetType, AssignValue);
+ return AssignValue;
}
+ assert(TargetType->getNumElements() < SourceType->getNumElements());
SmallVector<int> Mask(/* Size= */ TargetType->getNumElements());
for (unsigned I = 0; I < TargetType->getNumElements(); ++I)
Mask[I] = I;
diff --git a/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp b/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
index f7cdfcb..db036a5 100644
--- a/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
@@ -613,8 +613,7 @@ static void collectOtherInstr(MachineInstr &MI, SPIRV::ModuleAnalysisInfo &MAI,
<< FinalFlags << "\n";
MachineInstr *OrigMINonConst = const_cast<MachineInstr *>(OrigMI);
MachineOperand &OrigFlagsOp = OrigMINonConst->getOperand(2);
- OrigFlagsOp =
- MachineOperand::CreateImm(static_cast<unsigned>(FinalFlags));
+ OrigFlagsOp = MachineOperand::CreateImm(FinalFlags);
return; // Merge done, so we found a duplicate; don't add it to MAI.MS
}
}
diff --git a/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp b/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp
index db6f2d6..d538009 100644
--- a/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp
@@ -192,31 +192,43 @@ static void buildOpBitcast(SPIRVGlobalRegistry *GR, MachineIRBuilder &MIB,
.addUse(OpReg);
}
-// We do instruction selections early instead of calling MIB.buildBitcast()
-// generating the general op code G_BITCAST. When MachineVerifier validates
-// G_BITCAST we see a check of a kind: if Source Type is equal to Destination
-// Type then report error "bitcast must change the type". This doesn't take into
-// account the notion of a typed pointer that is important for SPIR-V where a
-// user may and should use bitcast between pointers with different pointee types
-// (https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpBitcast).
-// It's important for correct lowering in SPIR-V, because interpretation of the
-// data type is not left to instructions that utilize the pointer, but encoded
-// by the pointer declaration, and the SPIRV target can and must handle the
-// declaration and use of pointers that specify the type of data they point to.
-// It's not feasible to improve validation of G_BITCAST using just information
-// provided by low level types of source and destination. Therefore we don't
-// produce G_BITCAST as the general op code with semantics different from
-// OpBitcast, but rather lower to OpBitcast immediately. As for now, the only
-// difference would be that CombinerHelper couldn't transform known patterns
-// around G_BUILD_VECTOR. See discussion
-// in https://github.com/llvm/llvm-project/pull/110270 for even more context.
-static void selectOpBitcasts(MachineFunction &MF, SPIRVGlobalRegistry *GR,
- MachineIRBuilder MIB) {
+// We lower G_BITCAST to OpBitcast here to avoid a MachineVerifier error.
+// The verifier checks if the source and destination LLTs of a G_BITCAST are
+// different, but this check is too strict for SPIR-V's typed pointers, which
+// may have the same LLT but different SPIRVType (e.g. pointers to different
+// pointee types). By lowering to OpBitcast here, we bypass the verifier's
+// check. See discussion in https://github.com/llvm/llvm-project/pull/110270
+// for more context.
+//
+// We also handle the llvm.spv.bitcast intrinsic here. If the source and
+// destination SPIR-V types are the same, we lower it to a COPY to enable
+// further optimizations like copy propagation.
+static void lowerBitcasts(MachineFunction &MF, SPIRVGlobalRegistry *GR,
+ MachineIRBuilder MIB) {
SmallVector<MachineInstr *, 16> ToErase;
for (MachineBasicBlock &MBB : MF) {
for (MachineInstr &MI : MBB) {
+ if (isSpvIntrinsic(MI, Intrinsic::spv_bitcast)) {
+ Register DstReg = MI.getOperand(0).getReg();
+ Register SrcReg = MI.getOperand(2).getReg();
+ SPIRVType *DstType = GR->getSPIRVTypeForVReg(DstReg);
+ assert(
+ DstType &&
+ "Expected destination SPIR-V type to have been assigned already.");
+ SPIRVType *SrcType = GR->getSPIRVTypeForVReg(SrcReg);
+ assert(SrcType &&
+ "Expected source SPIR-V type to have been assigned already.");
+ if (DstType == SrcType) {
+ MIB.setInsertPt(*MI.getParent(), MI);
+ MIB.buildCopy(DstReg, SrcReg);
+ ToErase.push_back(&MI);
+ continue;
+ }
+ }
+
if (MI.getOpcode() != TargetOpcode::G_BITCAST)
continue;
+
MIB.setInsertPt(*MI.getParent(), MI);
buildOpBitcast(GR, MIB, MI.getOperand(0).getReg(),
MI.getOperand(1).getReg());
@@ -237,16 +249,11 @@ static void insertBitcasts(MachineFunction &MF, SPIRVGlobalRegistry *GR,
SmallVector<MachineInstr *, 10> ToErase;
for (MachineBasicBlock &MBB : MF) {
for (MachineInstr &MI : MBB) {
- if (!isSpvIntrinsic(MI, Intrinsic::spv_bitcast) &&
- !isSpvIntrinsic(MI, Intrinsic::spv_ptrcast))
+ if (!isSpvIntrinsic(MI, Intrinsic::spv_ptrcast))
continue;
assert(MI.getOperand(2).isReg());
MIB.setInsertPt(*MI.getParent(), MI);
ToErase.push_back(&MI);
- if (isSpvIntrinsic(MI, Intrinsic::spv_bitcast)) {
- MIB.buildBitcast(MI.getOperand(0).getReg(), MI.getOperand(2).getReg());
- continue;
- }
Register Def = MI.getOperand(0).getReg();
Register Source = MI.getOperand(2).getReg();
Type *ElemTy = getMDOperandAsType(MI.getOperand(3).getMetadata(), 0);
@@ -1089,7 +1096,7 @@ bool SPIRVPreLegalizer::runOnMachineFunction(MachineFunction &MF) {
removeImplicitFallthroughs(MF, MIB);
insertSpirvDecorations(MF, GR, MIB);
insertInlineAsm(MF, GR, ST, MIB);
- selectOpBitcasts(MF, GR, MIB);
+ lowerBitcasts(MF, GR, MIB);
return true;
}
generated by cgit v1.1 at 2025-11-01 07:18:25 +0000