Files
clang-p2996/llvm/lib/Target/DirectX/DXILPrepare.cpp
Finn Plummer a8ef75e758 [DirectX] Strip dx.rootsignatures metadata during dxil-prepare (#145746)
The `dx.rootsignatures` metadata is not recognized in DXIL, so failure
to remove this will cause validation errors.

This metadata is parsed (within `RootSignatureAnalysisWrapper`) into its
binary format. As such, once it has been used to construct the binary
form, it can be safely discarded without loss of information.

This pr ensures that the dxil prepare pass will depend and preserve on
the root signature analysis so that it runs before the metadata is
removed.

- Update `DXILPrepare.cpp` to preserve and depend on
`RootSignatureAnalysisWrapper`
- Update test to demonstrate order is correct
- Provide test-case to demonstrate the metadata is removed

Resolves https://github.com/llvm/llvm-project/issues/145437.

----------

Co-authored-by: Justin Bogner <mail@justinbogner.com>
2025-06-25 14:06:46 -07:00

325 lines
12 KiB
C++

//===- DXILPrepare.cpp - Prepare LLVM Module for DXIL encoding ------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file This file contains pases and utilities to convert a modern LLVM
/// module into a module compatible with the LLVM 3.7-based DirectX Intermediate
/// Language (DXIL).
//===----------------------------------------------------------------------===//
#include "DXILRootSignature.h"
#include "DXILShaderFlags.h"
#include "DirectX.h"
#include "DirectXIRPasses/PointerTypeAnalysis.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Analysis/DXILMetadataAnalysis.h"
#include "llvm/Analysis/DXILResource.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/AttributeMask.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Module.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/VersionTuple.h"
#define DEBUG_TYPE "dxil-prepare"
using namespace llvm;
using namespace llvm::dxil;
namespace {
constexpr bool isValidForDXIL(Attribute::AttrKind Attr) {
return is_contained({Attribute::Alignment,
Attribute::AlwaysInline,
Attribute::Builtin,
Attribute::ByVal,
Attribute::InAlloca,
Attribute::Cold,
Attribute::Convergent,
Attribute::InlineHint,
Attribute::InReg,
Attribute::JumpTable,
Attribute::MinSize,
Attribute::Naked,
Attribute::Nest,
Attribute::NoAlias,
Attribute::NoBuiltin,
Attribute::NoDuplicate,
Attribute::NoImplicitFloat,
Attribute::NoInline,
Attribute::NonLazyBind,
Attribute::NonNull,
Attribute::Dereferenceable,
Attribute::DereferenceableOrNull,
Attribute::Memory,
Attribute::NoRedZone,
Attribute::NoReturn,
Attribute::NoUnwind,
Attribute::OptimizeForSize,
Attribute::OptimizeNone,
Attribute::ReadNone,
Attribute::ReadOnly,
Attribute::Returned,
Attribute::ReturnsTwice,
Attribute::SExt,
Attribute::StackAlignment,
Attribute::StackProtect,
Attribute::StackProtectReq,
Attribute::StackProtectStrong,
Attribute::SafeStack,
Attribute::StructRet,
Attribute::SanitizeAddress,
Attribute::SanitizeThread,
Attribute::SanitizeMemory,
Attribute::UWTable,
Attribute::ZExt},
Attr);
}
static void collectDeadStringAttrs(AttributeMask &DeadAttrs, AttributeSet &&AS,
const StringSet<> &LiveKeys,
bool AllowExperimental) {
for (auto &Attr : AS) {
if (!Attr.isStringAttribute())
continue;
StringRef Key = Attr.getKindAsString();
if (LiveKeys.contains(Key))
continue;
if (AllowExperimental && Key.starts_with("exp-"))
continue;
DeadAttrs.addAttribute(Key);
}
}
static void removeStringFunctionAttributes(Function &F,
bool AllowExperimental) {
AttributeList Attrs = F.getAttributes();
const StringSet<> LiveKeys = {"waveops-include-helper-lanes",
"fp32-denorm-mode"};
// Collect DeadKeys in FnAttrs.
AttributeMask DeadAttrs;
collectDeadStringAttrs(DeadAttrs, Attrs.getFnAttrs(), LiveKeys,
AllowExperimental);
collectDeadStringAttrs(DeadAttrs, Attrs.getRetAttrs(), LiveKeys,
AllowExperimental);
F.removeFnAttrs(DeadAttrs);
F.removeRetAttrs(DeadAttrs);
}
static void cleanModuleFlags(Module &M) {
NamedMDNode *MDFlags = M.getModuleFlagsMetadata();
if (!MDFlags)
return;
SmallVector<llvm::Module::ModuleFlagEntry> FlagEntries;
M.getModuleFlagsMetadata(FlagEntries);
bool Updated = false;
for (auto &Flag : FlagEntries) {
// llvm 3.7 only supports behavior up to AppendUnique.
if (Flag.Behavior <= Module::ModFlagBehavior::AppendUnique)
continue;
Flag.Behavior = Module::ModFlagBehavior::Warning;
Updated = true;
}
if (!Updated)
return;
MDFlags->eraseFromParent();
for (auto &Flag : FlagEntries)
M.addModuleFlag(Flag.Behavior, Flag.Key->getString(), Flag.Val);
}
class DXILPrepareModule : public ModulePass {
static Value *maybeGenerateBitcast(IRBuilder<> &Builder,
PointerTypeMap &PointerTypes,
Instruction &Inst, Value *Operand,
Type *Ty) {
// Omit bitcasts if the incoming value matches the instruction type.
auto It = PointerTypes.find(Operand);
if (It != PointerTypes.end()) {
auto *OpTy = cast<TypedPointerType>(It->second)->getElementType();
if (OpTy == Ty)
return nullptr;
}
Type *ValTy = Operand->getType();
// Also omit the bitcast for matching global array types
if (auto *GlobalVar = dyn_cast<GlobalVariable>(Operand))
ValTy = GlobalVar->getValueType();
if (auto *AI = dyn_cast<AllocaInst>(Operand))
ValTy = AI->getAllocatedType();
if (auto *ArrTy = dyn_cast<ArrayType>(ValTy)) {
Type *ElTy = ArrTy->getElementType();
if (ElTy == Ty)
return nullptr;
}
// finally, drill down GEP instructions until we get the array
// that is being accessed, and compare element types
if (ConstantExpr *GEPInstr = dyn_cast<ConstantExpr>(Operand)) {
while (GEPInstr->getOpcode() == Instruction::GetElementPtr) {
Value *OpArg = GEPInstr->getOperand(0);
if (ConstantExpr *NewGEPInstr = dyn_cast<ConstantExpr>(OpArg)) {
GEPInstr = NewGEPInstr;
continue;
}
if (auto *GlobalVar = dyn_cast<GlobalVariable>(OpArg))
ValTy = GlobalVar->getValueType();
if (auto *AI = dyn_cast<AllocaInst>(Operand))
ValTy = AI->getAllocatedType();
if (auto *ArrTy = dyn_cast<ArrayType>(ValTy)) {
Type *ElTy = ArrTy->getElementType();
if (ElTy == Ty)
return nullptr;
}
break;
}
}
// Insert bitcasts where we are removing the instruction.
Builder.SetInsertPoint(&Inst);
// This code only gets hit in opaque-pointer mode, so the type of the
// pointer doesn't matter.
PointerType *PtrTy = cast<PointerType>(Operand->getType());
return Builder.Insert(
CastInst::Create(Instruction::BitCast, Operand,
Builder.getPtrTy(PtrTy->getAddressSpace())));
}
static std::array<unsigned, 6> getCompatibleInstructionMDs(llvm::Module &M) {
return {M.getMDKindID("dx.nonuniform"),
M.getMDKindID("dx.controlflow.hints"),
M.getMDKindID("dx.precise"),
llvm::LLVMContext::MD_range,
llvm::LLVMContext::MD_alias_scope,
llvm::LLVMContext::MD_noalias};
}
public:
bool runOnModule(Module &M) override {
PointerTypeMap PointerTypes = PointerTypeAnalysis::run(M);
AttributeMask AttrMask;
for (Attribute::AttrKind I = Attribute::None; I != Attribute::EndAttrKinds;
I = Attribute::AttrKind(I + 1)) {
if (!isValidForDXIL(I))
AttrMask.addAttribute(I);
}
const dxil::ModuleMetadataInfo MetadataInfo =
getAnalysis<DXILMetadataAnalysisWrapperPass>().getModuleMetadata();
VersionTuple ValVer = MetadataInfo.ValidatorVersion;
bool SkipValidation = ValVer.getMajor() == 0 && ValVer.getMinor() == 0;
// construct allowlist of valid metadata node kinds
std::array<unsigned, 6> DXILCompatibleMDs = getCompatibleInstructionMDs(M);
for (auto &F : M.functions()) {
F.removeFnAttrs(AttrMask);
F.removeRetAttrs(AttrMask);
// Only remove string attributes if we are not skipping validation.
// This will reserve the experimental attributes when validation version
// is 0.0 for experiment mode.
removeStringFunctionAttributes(F, SkipValidation);
for (size_t Idx = 0, End = F.arg_size(); Idx < End; ++Idx)
F.removeParamAttrs(Idx, AttrMask);
for (auto &BB : F) {
IRBuilder<> Builder(&BB);
for (auto &I : make_early_inc_range(BB)) {
I.dropUnknownNonDebugMetadata(DXILCompatibleMDs);
// Emtting NoOp bitcast instructions allows the ValueEnumerator to be
// unmodified as it reserves instruction IDs during contruction.
if (auto LI = dyn_cast<LoadInst>(&I)) {
if (Value *NoOpBitcast = maybeGenerateBitcast(
Builder, PointerTypes, I, LI->getPointerOperand(),
LI->getType())) {
LI->replaceAllUsesWith(
Builder.CreateLoad(LI->getType(), NoOpBitcast));
LI->eraseFromParent();
}
continue;
}
if (auto SI = dyn_cast<StoreInst>(&I)) {
if (Value *NoOpBitcast = maybeGenerateBitcast(
Builder, PointerTypes, I, SI->getPointerOperand(),
SI->getValueOperand()->getType())) {
SI->replaceAllUsesWith(
Builder.CreateStore(SI->getValueOperand(), NoOpBitcast));
SI->eraseFromParent();
}
continue;
}
if (auto GEP = dyn_cast<GetElementPtrInst>(&I)) {
if (Value *NoOpBitcast = maybeGenerateBitcast(
Builder, PointerTypes, I, GEP->getPointerOperand(),
GEP->getSourceElementType()))
GEP->setOperand(0, NoOpBitcast);
continue;
}
if (auto *CB = dyn_cast<CallBase>(&I)) {
CB->removeFnAttrs(AttrMask);
CB->removeRetAttrs(AttrMask);
for (size_t Idx = 0, End = CB->arg_size(); Idx < End; ++Idx)
CB->removeParamAttrs(Idx, AttrMask);
continue;
}
}
}
}
// Remove flags not for DXIL.
cleanModuleFlags(M);
// dx.rootsignatures will have been parsed from its metadata form as its
// binary form as part of the RootSignatureAnalysisWrapper, so safely
// remove it as it is not recognized in DXIL
if (NamedMDNode *RootSignature = M.getNamedMetadata("dx.rootsignatures"))
RootSignature->eraseFromParent();
return true;
}
DXILPrepareModule() : ModulePass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<DXILMetadataAnalysisWrapperPass>();
AU.addRequired<RootSignatureAnalysisWrapper>();
AU.addPreserved<RootSignatureAnalysisWrapper>();
AU.addPreserved<ShaderFlagsAnalysisWrapper>();
AU.addPreserved<DXILMetadataAnalysisWrapperPass>();
AU.addPreserved<DXILResourceWrapperPass>();
}
static char ID; // Pass identification.
};
char DXILPrepareModule::ID = 0;
} // end anonymous namespace
INITIALIZE_PASS_BEGIN(DXILPrepareModule, DEBUG_TYPE, "DXIL Prepare Module",
false, false)
INITIALIZE_PASS_DEPENDENCY(DXILMetadataAnalysisWrapperPass)
INITIALIZE_PASS_DEPENDENCY(RootSignatureAnalysisWrapper)
INITIALIZE_PASS_END(DXILPrepareModule, DEBUG_TYPE, "DXIL Prepare Module", false,
false)
ModulePass *llvm::createDXILPrepareModulePass() {
return new DXILPrepareModule();
}