llvm/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp

//===- ThinLTOBitcodeWriter.cpp - Bitcode writing pass for ThinLTO --------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/ModuleSummaryAnalysis.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Analysis/TypeMetadataUtils.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Object/ModuleSymbolTable.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/FunctionAttrs.h"
#include "llvm/Transforms/IPO/FunctionImport.h"
#include "llvm/Transforms/IPO/LowerTypeTests.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
usingnamespacellvm;

namespace {

// Determine if a promotion alias should be created for a symbol name.
static bool allowPromotionAlias(const std::string &Name) { … }

// Promote each local-linkage entity defined by ExportM and used by ImportM by
// changing visibility and appending the given ModuleId.
void promoteInternals(Module &ExportM, Module &ImportM, StringRef ModuleId,
                      SetVector<GlobalValue *> &PromoteExtra) { … }

// Promote all internal (i.e. distinct) type ids used by the module by replacing
// them with external type ids formed using the module id.
//
// Note that this needs to be done before we clone the module because each clone
// will receive its own set of distinct metadata nodes.
void promoteTypeIds(Module &M, StringRef ModuleId) { … }

// Drop unused globals, and drop type information from function declarations.
// FIXME: If we made functions typeless then there would be no need to do this.
void simplifyExternals(Module &M) { … }

static void
filterModule(Module *M,
             function_ref<bool(const GlobalValue *)> ShouldKeepDefinition) { … }

void forEachVirtualFunction(Constant *C, function_ref<void(Function *)> Fn) { … }

// Clone any @llvm[.compiler].used over to the new module and append
// values whose defs were cloned into that module.
static void cloneUsedGlobalVariables(const Module &SrcM, Module &DestM,
                                     bool CompilerUsed) { … }

#ifndef NDEBUG
static bool enableUnifiedLTO(Module &M) {
  bool UnifiedLTO = false;
  if (auto *MD =
          mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("UnifiedLTO")))
    UnifiedLTO = MD->getZExtValue();
  return UnifiedLTO;
}
#endif

// If it's possible to split M into regular and thin LTO parts, do so and write
// a multi-module bitcode file with the two parts to OS. Otherwise, write only a
// regular LTO bitcode file to OS.
void splitAndWriteThinLTOBitcode(
    raw_ostream &OS, raw_ostream *ThinLinkOS,
    function_ref<AAResults &(Function &)> AARGetter, Module &M) { … }

// Check if the LTO Unit splitting has been enabled.
bool enableSplitLTOUnit(Module &M) { … }

// Returns whether this module needs to be split because it uses type metadata.
bool hasTypeMetadata(Module &M) { … }

bool writeThinLTOBitcode(raw_ostream &OS, raw_ostream *ThinLinkOS,
                         function_ref<AAResults &(Function &)> AARGetter,
                         Module &M, const ModuleSummaryIndex *Index) { … }

} // anonymous namespace
extern bool WriteNewDbgInfoFormatToBitcode;
PreservedAnalyses
llvm::ThinLTOBitcodeWriterPass::run(Module &M, ModuleAnalysisManager &AM) { … }