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[AMDGPU] Split struct kernel arguments #133786

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[AMDGPU] Split struct kernel arguments #133786

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9 changes: 9 additions & 0 deletions llvm/lib/Target/AMDGPU/AMDGPU.h
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,15 @@ struct AMDGPUPromoteKernelArgumentsPass
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
};

ModulePass *createAMDGPUSplitKernelArgumentsPass();
void initializeAMDGPUSplitKernelArgumentsPass(PassRegistry &);
extern char &AMDGPUSplitKernelArgumentsID;

struct AMDGPUSplitKernelArgumentsPass
: PassInfoMixin<AMDGPUSplitKernelArgumentsPass> {
PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
};

ModulePass *createAMDGPULowerKernelAttributesPass();
void initializeAMDGPULowerKernelAttributesPass(PassRegistry &);
extern char &AMDGPULowerKernelAttributesID;
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33 changes: 30 additions & 3 deletions llvm/lib/Target/AMDGPU/AMDGPUHSAMetadataStreamer.cpp
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Expand Up @@ -357,17 +357,38 @@ void MetadataStreamerMsgPackV4::emitKernelArg(const Argument &Arg,
Align ArgAlign;
std::tie(ArgTy, ArgAlign) = getArgumentTypeAlign(Arg, DL);

// Assuming the argument is not split from struct-type argument by default,
// unless we find it in function attribute amdgpu-argument-mapping.
unsigned OriginalArgIndex = ~0U;
uint64_t OriginalArgOffset = 0;
Attribute Attr =
Func->getAttributes().getParamAttr(ArgNo, "amdgpu-original-arg");
if (Attr.isValid()) {
StringRef MappingStr = Attr.getValueAsString();
SmallVector<StringRef, 2> Elements;
MappingStr.split(Elements, ':');
if (Elements.size() == 2) {
if (Elements[0].getAsInteger(10, OriginalArgIndex))
report_fatal_error(
"Invalid original argument index in amdgpu-original-arg attribute");
if (Elements[1].getAsInteger(10, OriginalArgOffset))
report_fatal_error("Invalid original argument offset in "
"amdgpu-original-arg attribute");
}
}

emitKernelArg(DL, ArgTy, ArgAlign,
getValueKind(ArgTy, TypeQual, BaseTypeName), Offset, Args,
PointeeAlign, Name, TypeName, BaseTypeName, ActAccQual,
AccQual, TypeQual);
PointeeAlign, Name, TypeName, BaseTypeName, ActAccQual, AccQual,
TypeQual, OriginalArgIndex, OriginalArgOffset);
}

void MetadataStreamerMsgPackV4::emitKernelArg(
const DataLayout &DL, Type *Ty, Align Alignment, StringRef ValueKind,
unsigned &Offset, msgpack::ArrayDocNode Args, MaybeAlign PointeeAlign,
StringRef Name, StringRef TypeName, StringRef BaseTypeName,
StringRef ActAccQual, StringRef AccQual, StringRef TypeQual) {
StringRef ActAccQual, StringRef AccQual, StringRef TypeQual,
unsigned OriginalArgIndex, uint64_t OriginalArgOffset) {
auto Arg = Args.getDocument()->getMapNode();

if (!Name.empty())
Expand Down Expand Up @@ -409,6 +430,12 @@ void MetadataStreamerMsgPackV4::emitKernelArg(
Arg[".is_pipe"] = Arg.getDocument()->getNode(true);
}

// Add original argument index and offset to the metadata
if (OriginalArgIndex != ~0U) {
Arg[".original_arg_index"] = Arg.getDocument()->getNode(OriginalArgIndex);
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@shiltian shiltian Jun 9, 2025

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Honestly, I agree with @arsenm that this is indeed an ABI breaking change, even though the ABI change seems to be transparent to end users.

Arg[".original_arg_offset"] = Arg.getDocument()->getNode(OriginalArgOffset);
}

Args.push_back(Arg);
}

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4 changes: 3 additions & 1 deletion llvm/lib/Target/AMDGPU/AMDGPUHSAMetadataStreamer.h
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Expand Up @@ -116,7 +116,9 @@ class LLVM_EXTERNAL_VISIBILITY MetadataStreamerMsgPackV4
MaybeAlign PointeeAlign = std::nullopt,
StringRef Name = "", StringRef TypeName = "",
StringRef BaseTypeName = "", StringRef ActAccQual = "",
StringRef AccQual = "", StringRef TypeQual = "");
StringRef AccQual = "", StringRef TypeQual = "",
unsigned OriginalArgIndex = ~0U,
uint64_t OriginalArgOffset = 0);

void emitHiddenKernelArgs(const MachineFunction &MF, unsigned &Offset,
msgpack::ArrayDocNode Args) override;
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1 change: 1 addition & 0 deletions llvm/lib/Target/AMDGPU/AMDGPUPassRegistry.def
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Expand Up @@ -30,6 +30,7 @@ MODULE_PASS("amdgpu-printf-runtime-binding", AMDGPUPrintfRuntimeBindingPass())
MODULE_PASS("amdgpu-remove-incompatible-functions", AMDGPURemoveIncompatibleFunctionsPass(*this))
MODULE_PASS("amdgpu-sw-lower-lds", AMDGPUSwLowerLDSPass(*this))
MODULE_PASS("amdgpu-unify-metadata", AMDGPUUnifyMetadataPass())
MODULE_PASS("amdgpu-split-kernel-arguments", AMDGPUSplitKernelArgumentsPass())
#undef MODULE_PASS

#ifndef MODULE_PASS_WITH_PARAMS
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