c8b3d79961
This PR introduces a Metadata Node Kind allowlist. The purpose is to prevent newer Metadata Node Kinds to be used and inserted into the outputted DXIL module. Only the metadata kinds that are accepted in the DXIL Validator are on the allowlist. The Github DXC validator doesn't support these newer Metadata Node Kinds, so we need to filter them out. We introduce this restrictive allowlist into LLVM and strip all metadata that isn't found in the list. The accompanying test would add the `llvm.loop.mustprogress` metadata node kind, but thanks to the allowlist, filters it out, and so the whitelist is proven to work. The test also has two separate metadata kinds that are on the allowlist, and remain after the DXIL Prepare pass.
283 lines
10 KiB
C++
283 lines
10 KiB
C++
//===- DXILPrepare.cpp - Prepare LLVM Module for DXIL encoding ------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file This file contains pases and utilities to convert a modern LLVM
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/// module into a module compatible with the LLVM 3.7-based DirectX Intermediate
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/// Language (DXIL).
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//===----------------------------------------------------------------------===//
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#include "DXILShaderFlags.h"
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#include "DirectX.h"
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#include "DirectXIRPasses/PointerTypeAnalysis.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringSet.h"
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#include "llvm/Analysis/DXILMetadataAnalysis.h"
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#include "llvm/Analysis/DXILResource.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/IR/AttributeMask.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Module.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/VersionTuple.h"
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#define DEBUG_TYPE "dxil-prepare"
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using namespace llvm;
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using namespace llvm::dxil;
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namespace {
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constexpr bool isValidForDXIL(Attribute::AttrKind Attr) {
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return is_contained({Attribute::Alignment,
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Attribute::AlwaysInline,
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Attribute::Builtin,
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Attribute::ByVal,
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Attribute::InAlloca,
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Attribute::Cold,
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Attribute::Convergent,
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Attribute::InlineHint,
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Attribute::InReg,
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Attribute::JumpTable,
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Attribute::MinSize,
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Attribute::Naked,
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Attribute::Nest,
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Attribute::NoAlias,
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Attribute::NoBuiltin,
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Attribute::NoDuplicate,
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Attribute::NoImplicitFloat,
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Attribute::NoInline,
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Attribute::NonLazyBind,
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Attribute::NonNull,
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Attribute::Dereferenceable,
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Attribute::DereferenceableOrNull,
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Attribute::Memory,
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Attribute::NoRedZone,
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Attribute::NoReturn,
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Attribute::NoUnwind,
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Attribute::OptimizeForSize,
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Attribute::OptimizeNone,
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Attribute::ReadNone,
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Attribute::ReadOnly,
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Attribute::Returned,
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Attribute::ReturnsTwice,
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Attribute::SExt,
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Attribute::StackAlignment,
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Attribute::StackProtect,
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Attribute::StackProtectReq,
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Attribute::StackProtectStrong,
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Attribute::SafeStack,
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Attribute::StructRet,
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Attribute::SanitizeAddress,
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Attribute::SanitizeThread,
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Attribute::SanitizeMemory,
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Attribute::UWTable,
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Attribute::ZExt},
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Attr);
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}
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static void collectDeadStringAttrs(AttributeMask &DeadAttrs, AttributeSet &&AS,
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const StringSet<> &LiveKeys,
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bool AllowExperimental) {
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for (auto &Attr : AS) {
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if (!Attr.isStringAttribute())
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continue;
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StringRef Key = Attr.getKindAsString();
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if (LiveKeys.contains(Key))
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continue;
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if (AllowExperimental && Key.starts_with("exp-"))
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continue;
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DeadAttrs.addAttribute(Key);
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}
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}
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static void removeStringFunctionAttributes(Function &F,
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bool AllowExperimental) {
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AttributeList Attrs = F.getAttributes();
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const StringSet<> LiveKeys = {"waveops-include-helper-lanes",
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"fp32-denorm-mode"};
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// Collect DeadKeys in FnAttrs.
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AttributeMask DeadAttrs;
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collectDeadStringAttrs(DeadAttrs, Attrs.getFnAttrs(), LiveKeys,
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AllowExperimental);
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collectDeadStringAttrs(DeadAttrs, Attrs.getRetAttrs(), LiveKeys,
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AllowExperimental);
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F.removeFnAttrs(DeadAttrs);
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F.removeRetAttrs(DeadAttrs);
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}
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static void cleanModuleFlags(Module &M) {
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NamedMDNode *MDFlags = M.getModuleFlagsMetadata();
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if (!MDFlags)
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return;
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SmallVector<llvm::Module::ModuleFlagEntry> FlagEntries;
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M.getModuleFlagsMetadata(FlagEntries);
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bool Updated = false;
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for (auto &Flag : FlagEntries) {
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// llvm 3.7 only supports behavior up to AppendUnique.
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if (Flag.Behavior <= Module::ModFlagBehavior::AppendUnique)
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continue;
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Flag.Behavior = Module::ModFlagBehavior::Warning;
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Updated = true;
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}
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if (!Updated)
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return;
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MDFlags->eraseFromParent();
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for (auto &Flag : FlagEntries)
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M.addModuleFlag(Flag.Behavior, Flag.Key->getString(), Flag.Val);
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}
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class DXILPrepareModule : public ModulePass {
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static Value *maybeGenerateBitcast(IRBuilder<> &Builder,
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PointerTypeMap &PointerTypes,
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Instruction &Inst, Value *Operand,
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Type *Ty) {
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// Omit bitcasts if the incoming value matches the instruction type.
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auto It = PointerTypes.find(Operand);
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if (It != PointerTypes.end())
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if (cast<TypedPointerType>(It->second)->getElementType() == Ty)
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return nullptr;
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// Insert bitcasts where we are removing the instruction.
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Builder.SetInsertPoint(&Inst);
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// This code only gets hit in opaque-pointer mode, so the type of the
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// pointer doesn't matter.
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PointerType *PtrTy = cast<PointerType>(Operand->getType());
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return Builder.Insert(
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CastInst::Create(Instruction::BitCast, Operand,
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Builder.getPtrTy(PtrTy->getAddressSpace())));
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}
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static std::array<unsigned, 6> getCompatibleInstructionMDs(llvm::Module &M) {
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return {M.getMDKindID("dx.nonuniform"),
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M.getMDKindID("dx.controlflow.hints"),
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M.getMDKindID("dx.precise"),
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llvm::LLVMContext::MD_range,
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llvm::LLVMContext::MD_alias_scope,
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llvm::LLVMContext::MD_noalias};
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}
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public:
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bool runOnModule(Module &M) override {
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PointerTypeMap PointerTypes = PointerTypeAnalysis::run(M);
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AttributeMask AttrMask;
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for (Attribute::AttrKind I = Attribute::None; I != Attribute::EndAttrKinds;
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I = Attribute::AttrKind(I + 1)) {
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if (!isValidForDXIL(I))
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AttrMask.addAttribute(I);
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}
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const dxil::ModuleMetadataInfo MetadataInfo =
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getAnalysis<DXILMetadataAnalysisWrapperPass>().getModuleMetadata();
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VersionTuple ValVer = MetadataInfo.ValidatorVersion;
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bool SkipValidation = ValVer.getMajor() == 0 && ValVer.getMinor() == 0;
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// construct allowlist of valid metadata node kinds
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std::array<unsigned, 6> DXILCompatibleMDs = getCompatibleInstructionMDs(M);
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for (auto &F : M.functions()) {
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F.removeFnAttrs(AttrMask);
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F.removeRetAttrs(AttrMask);
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// Only remove string attributes if we are not skipping validation.
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// This will reserve the experimental attributes when validation version
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// is 0.0 for experiment mode.
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removeStringFunctionAttributes(F, SkipValidation);
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for (size_t Idx = 0, End = F.arg_size(); Idx < End; ++Idx)
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F.removeParamAttrs(Idx, AttrMask);
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for (auto &BB : F) {
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IRBuilder<> Builder(&BB);
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for (auto &I : make_early_inc_range(BB)) {
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I.dropUnknownNonDebugMetadata(DXILCompatibleMDs);
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if (I.getOpcode() == Instruction::FNeg) {
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Builder.SetInsertPoint(&I);
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Value *In = I.getOperand(0);
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Value *Zero = ConstantFP::get(In->getType(), -0.0);
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I.replaceAllUsesWith(Builder.CreateFSub(Zero, In));
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I.eraseFromParent();
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continue;
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}
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// Emtting NoOp bitcast instructions allows the ValueEnumerator to be
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// unmodified as it reserves instruction IDs during contruction.
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if (auto LI = dyn_cast<LoadInst>(&I)) {
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if (Value *NoOpBitcast = maybeGenerateBitcast(
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Builder, PointerTypes, I, LI->getPointerOperand(),
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LI->getType())) {
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LI->replaceAllUsesWith(
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Builder.CreateLoad(LI->getType(), NoOpBitcast));
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LI->eraseFromParent();
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}
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continue;
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}
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if (auto SI = dyn_cast<StoreInst>(&I)) {
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if (Value *NoOpBitcast = maybeGenerateBitcast(
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Builder, PointerTypes, I, SI->getPointerOperand(),
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SI->getValueOperand()->getType())) {
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SI->replaceAllUsesWith(
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Builder.CreateStore(SI->getValueOperand(), NoOpBitcast));
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SI->eraseFromParent();
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}
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continue;
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}
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if (auto GEP = dyn_cast<GetElementPtrInst>(&I)) {
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if (Value *NoOpBitcast = maybeGenerateBitcast(
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Builder, PointerTypes, I, GEP->getPointerOperand(),
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GEP->getSourceElementType()))
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GEP->setOperand(0, NoOpBitcast);
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continue;
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}
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if (auto *CB = dyn_cast<CallBase>(&I)) {
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CB->removeFnAttrs(AttrMask);
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CB->removeRetAttrs(AttrMask);
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for (size_t Idx = 0, End = CB->arg_size(); Idx < End; ++Idx)
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CB->removeParamAttrs(Idx, AttrMask);
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continue;
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}
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}
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}
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}
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// Remove flags not for DXIL.
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cleanModuleFlags(M);
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return true;
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}
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DXILPrepareModule() : ModulePass(ID) {}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addRequired<DXILMetadataAnalysisWrapperPass>();
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AU.addPreserved<ShaderFlagsAnalysisWrapper>();
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AU.addPreserved<DXILMetadataAnalysisWrapperPass>();
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AU.addPreserved<DXILResourceWrapperPass>();
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}
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static char ID; // Pass identification.
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};
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char DXILPrepareModule::ID = 0;
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} // end anonymous namespace
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INITIALIZE_PASS_BEGIN(DXILPrepareModule, DEBUG_TYPE, "DXIL Prepare Module",
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false, false)
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INITIALIZE_PASS_DEPENDENCY(DXILMetadataAnalysisWrapperPass)
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INITIALIZE_PASS_END(DXILPrepareModule, DEBUG_TYPE, "DXIL Prepare Module", false,
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false)
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ModulePass *llvm::createDXILPrepareModulePass() {
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return new DXILPrepareModule();
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}
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