DXContainerGlobals.cpp

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//===- DXContainerGlobals.cpp - DXContainer global generator pass ---------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// DXContainerGlobalsPass implementation.
//
//===----------------------------------------------------------------------===//
 
#include "DXILShaderFlags.h"
#include "DirectX.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/DXContainer.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Constants.h"
#include "llvm/InitializePasses.h"
#include "llvm/MC/DXContainerPSVInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/MD5.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
 
using namespace llvm;
using namespace llvm::dxil;
using namespace llvm::mcdxbc;
 
namespace {
class DXContainerGlobals : public llvm::ModulePass {
 
  GlobalVariable *buildContainerGlobal(Module &M, Constant *Content,
                                       StringRef Name, StringRef SectionName);
  GlobalVariable *getFeatureFlags(Module &M);
  GlobalVariable *computeShaderHash(Module &M);
  GlobalVariable *buildSignature(Module &M, Signature &Sig, StringRef Name,
                                 StringRef SectionName);
  void addSignature(Module &M, SmallVector<GlobalValue *> &Globals);
 
public:
  static char ID; // Pass identification, replacement for typeid
  DXContainerGlobals() : ModulePass(ID) {
    initializeDXContainerGlobalsPass(*PassRegistry::getPassRegistry());
  }
 
  StringRef getPassName() const override {
    return "DXContainer Global Emitter";
  }
 
  bool runOnModule(Module &M) override;
 
  void getAnalysisUsage(AnalysisUsage &AU) const override {
    AU.setPreservesAll();
    AU.addRequired<ShaderFlagsAnalysisWrapper>();
  }
};
 
} // namespace
 
bool DXContainerGlobals::runOnModule(Module &M) {
  llvm::SmallVector<GlobalValue *> Globals;
  Globals.push_back(getFeatureFlags(M));
  Globals.push_back(computeShaderHash(M));
  addSignature(M, Globals);
  appendToCompilerUsed(M, Globals);
  return true;
}
 
GlobalVariable *DXContainerGlobals::getFeatureFlags(Module &M) {
  const uint64_t FeatureFlags =
      static_cast<uint64_t>(getAnalysis<ShaderFlagsAnalysisWrapper>()
                                .getShaderFlags()
                                .getFeatureFlags());
 
  Constant *FeatureFlagsConstant =
      ConstantInt::get(M.getContext(), APInt(64, FeatureFlags));
  return buildContainerGlobal(M, FeatureFlagsConstant, "dx.sfi0", "SFI0");
}
 
GlobalVariable *DXContainerGlobals::computeShaderHash(Module &M) {
  auto *DXILConstant =
      cast<ConstantDataArray>(M.getNamedGlobal("dx.dxil")->getInitializer());
  MD5 Digest;
  Digest.update(DXILConstant->getRawDataValues());
  MD5::MD5Result Result = Digest.final();
 
  dxbc::ShaderHash HashData = {0, {0}};
  // The Hash's IncludesSource flag gets set whenever the hashed shader includes
  // debug information.
  if (M.debug_compile_units_begin() != M.debug_compile_units_end())
    HashData.Flags = static_cast<uint32_t>(dxbc::HashFlags::IncludesSource);
 
  memcpy(reinterpret_cast<void *>(&HashData.Digest), Result.data(), 16);
  if (sys::IsBigEndianHost)
    HashData.swapBytes();
  StringRef Data(reinterpret_cast<char *>(&HashData), sizeof(dxbc::ShaderHash));
 
  Constant *ModuleConstant =
      ConstantDataArray::get(M.getContext(), arrayRefFromStringRef(Data));
  return buildContainerGlobal(M, ModuleConstant, "dx.hash", "HASH");
}
 
GlobalVariable *DXContainerGlobals::buildContainerGlobal(
    Module &M, Constant *Content, StringRef Name, StringRef SectionName) {
  auto *GV = new llvm::GlobalVariable(
      M, Content->getType(), true, GlobalValue::PrivateLinkage, Content, Name);
  GV->setSection(SectionName);
  GV->setAlignment(Align(4));
  return GV;
}
 
GlobalVariable *DXContainerGlobals::buildSignature(Module &M, Signature &Sig,
                                                   StringRef Name,
                                                   StringRef SectionName) {
  SmallString<256> Data;
  raw_svector_ostream OS(Data);
  Sig.write(OS);
  Constant *Constant =
      ConstantDataArray::getString(M.getContext(), Data, /*AddNull*/ false);
  return buildContainerGlobal(M, Constant, Name, SectionName);
}
 
void DXContainerGlobals::addSignature(Module &M,
                                      SmallVector<GlobalValue *> &Globals) {
  // FIXME: support graphics shader.
  //  see issue https://github.com/llvm/llvm-project/issues/90504.
 
  Signature InputSig;
  Globals.emplace_back(buildSignature(M, InputSig, "dx.isg1", "ISG1"));
 
  Signature OutputSig;
  Globals.emplace_back(buildSignature(M, OutputSig, "dx.osg1", "OSG1"));
}
 
char DXContainerGlobals::ID = 0;
INITIALIZE_PASS_BEGIN(DXContainerGlobals, "dxil-globals",
                      "DXContainer Global Emitter", false, true)
INITIALIZE_PASS_DEPENDENCY(ShaderFlagsAnalysisWrapper)
INITIALIZE_PASS_END(DXContainerGlobals, "dxil-globals",
                    "DXContainer Global Emitter", false, true)
 
ModulePass *llvm::createDXContainerGlobalsPass() {
  return new DXContainerGlobals();
}