Move LTO support library to a component, allowing it to be tested

more reliably across platforms. Patch by Tom Roeder! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191343 91177308-0d34-0410-b5e6-96231b3b80d8
2025-06-19 03:24:09 +00:00 · 2013-09-24 23:52:22 +00:00
parent 85509802eb
commit cc48854d5d
20 changed files with 136 additions and 59 deletions
--- a/lib/LTO/LTOCodeGenerator.cpp
+++ b/lib/LTO/LTOCodeGenerator.cpp
@ -0,0 +1,453 @@
+//===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Link Time Optimization library. This library is
+// intended to be used by linker to optimize code at link time.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/LTO/LTOCodeGenerator.h"
+#include "llvm/LTO/LTOModule.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Analysis/Passes.h"
+#include "llvm/Analysis/Verifier.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Config/config.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Linker.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/SubtargetFeature.h"
+#include "llvm/PassManager.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FormattedStream.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Signals.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/ToolOutputFile.h"
+#include "llvm/Support/system_error.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/Mangler.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/PassManagerBuilder.h"
+#include "llvm/Transforms/ObjCARC.h"
+using namespace llvm;
+
+static cl::opt<bool>
+DisableOpt("disable-opt", cl::init(false),
+  cl::desc("Do not run any optimization passes"));
+
+static cl::opt<bool>
+DisableInline("disable-inlining", cl::init(false),
+  cl::desc("Do not run the inliner pass"));
+
+static cl::opt<bool>
+DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
+  cl::desc("Do not run the GVN load PRE pass"));
+
+const char* LTOCodeGenerator::getVersionString() {
+#ifdef LLVM_VERSION_INFO
+  return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
+#else
+  return PACKAGE_NAME " version " PACKAGE_VERSION;
+#endif
+}
+
+LTOCodeGenerator::LTOCodeGenerator()
+    : Context(getGlobalContext()), Linker(new Module("ld-temp.o", Context)),
+      TargetMach(NULL), EmitDwarfDebugInfo(false), ScopeRestrictionsDone(false),
+      CodeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC), NativeObjectFile(NULL) {
+  initializeLTOPasses();
+}
+
+LTOCodeGenerator::~LTOCodeGenerator() {
+  delete TargetMach;
+  delete NativeObjectFile;
+  delete Linker.getModule();
+
+  for (std::vector<char *>::iterator I = CodegenOptions.begin(),
+                                     E = CodegenOptions.end();
+       I != E; ++I)
+    free(*I);
+}
+
+// Initialize LTO passes. Please keep this funciton in sync with
+// PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
+// passes are initialized. 
+//
+void LTOCodeGenerator::initializeLTOPasses() {
+  PassRegistry &R = *PassRegistry::getPassRegistry();
+
+  initializeInternalizePassPass(R);
+  initializeIPSCCPPass(R);
+  initializeGlobalOptPass(R);
+  initializeConstantMergePass(R);
+  initializeDAHPass(R);
+  initializeInstCombinerPass(R);
+  initializeSimpleInlinerPass(R);
+  initializePruneEHPass(R);
+  initializeGlobalDCEPass(R);
+  initializeArgPromotionPass(R);
+  initializeJumpThreadingPass(R);
+  initializeSROAPass(R);
+  initializeSROA_DTPass(R);
+  initializeSROA_SSAUpPass(R);
+  initializeFunctionAttrsPass(R);
+  initializeGlobalsModRefPass(R);
+  initializeLICMPass(R);
+  initializeGVNPass(R);
+  initializeMemCpyOptPass(R);
+  initializeDCEPass(R);
+  initializeCFGSimplifyPassPass(R);
+}
+
+bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {
+  bool ret = Linker.linkInModule(mod->getLLVVMModule(), &errMsg);
+
+  const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
+  for (int i = 0, e = undefs.size(); i != e; ++i)
+    AsmUndefinedRefs[undefs[i]] = 1;
+
+  return !ret;
+}
+
+void LTOCodeGenerator::setDebugInfo(lto_debug_model debug) {
+  switch (debug) {
+  case LTO_DEBUG_MODEL_NONE:
+    EmitDwarfDebugInfo = false;
+    return;
+
+  case LTO_DEBUG_MODEL_DWARF:
+    EmitDwarfDebugInfo = true;
+    return;
+  }
+  llvm_unreachable("Unknown debug format!");
+}
+
+void LTOCodeGenerator::setCodePICModel(lto_codegen_model model) {
+  switch (model) {
+  case LTO_CODEGEN_PIC_MODEL_STATIC:
+  case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
+  case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
+    CodeModel = model;
+    return;
+  }
+  llvm_unreachable("Unknown PIC model!");
+}
+
+bool LTOCodeGenerator::writeMergedModules(const char *path,
+                                          std::string &errMsg) {
+  if (!determineTarget(errMsg))
+    return false;
+
+  // mark which symbols can not be internalized
+  applyScopeRestrictions();
+
+  // create output file
+  std::string ErrInfo;
+  tool_output_file Out(path, ErrInfo, sys::fs::F_Binary);
+  if (!ErrInfo.empty()) {
+    errMsg = "could not open bitcode file for writing: ";
+    errMsg += path;
+    return false;
+  }
+
+  // write bitcode to it
+  WriteBitcodeToFile(Linker.getModule(), Out.os());
+  Out.os().close();
+
+  if (Out.os().has_error()) {
+    errMsg = "could not write bitcode file: ";
+    errMsg += path;
+    Out.os().clear_error();
+    return false;
+  }
+
+  Out.keep();
+  return true;
+}
+
+bool LTOCodeGenerator::compile_to_file(const char** name, std::string& errMsg) {
+  // make unique temp .o file to put generated object file
+  SmallString<128> Filename;
+  int FD;
+  error_code EC = sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filename);
+  if (EC) {
+    errMsg = EC.message();
+    return false;
+  }
+
+  // generate object file
+  tool_output_file objFile(Filename.c_str(), FD);
+
+  bool genResult = generateObjectFile(objFile.os(), errMsg);
+  objFile.os().close();
+  if (objFile.os().has_error()) {
+    objFile.os().clear_error();
+    sys::fs::remove(Twine(Filename));
+    return false;
+  }
+
+  objFile.keep();
+  if (!genResult) {
+    sys::fs::remove(Twine(Filename));
+    return false;
+  }
+
+  NativeObjectPath = Filename.c_str();
+  *name = NativeObjectPath.c_str();
+  return true;
+}
+
+const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg) {
+  const char *name;
+  if (!compile_to_file(&name, errMsg))
+    return NULL;
+
+  // remove old buffer if compile() called twice
+  delete NativeObjectFile;
+
+  // read .o file into memory buffer
+  OwningPtr<MemoryBuffer> BuffPtr;
+  if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) {
+    errMsg = ec.message();
+    sys::fs::remove(NativeObjectPath);
+    return NULL;
+  }
+  NativeObjectFile = BuffPtr.take();
+
+  // remove temp files
+  sys::fs::remove(NativeObjectPath);
+
+  // return buffer, unless error
+  if (NativeObjectFile == NULL)
+    return NULL;
+  *length = NativeObjectFile->getBufferSize();
+  return NativeObjectFile->getBufferStart();
+}
+
+bool LTOCodeGenerator::determineTarget(std::string &errMsg) {
+  if (TargetMach != NULL)
+    return true;
+
+  // if options were requested, set them
+  if (!CodegenOptions.empty())
+    cl::ParseCommandLineOptions(CodegenOptions.size(),
+                                const_cast<char **>(&CodegenOptions[0]));
+
+  std::string TripleStr = Linker.getModule()->getTargetTriple();
+  if (TripleStr.empty())
+    TripleStr = sys::getDefaultTargetTriple();
+  llvm::Triple Triple(TripleStr);
+
+  // create target machine from info for merged modules
+  const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
+  if (march == NULL)
+    return false;
+
+  // The relocation model is actually a static member of TargetMachine and
+  // needs to be set before the TargetMachine is instantiated.
+  Reloc::Model RelocModel = Reloc::Default;
+  switch (CodeModel) {
+  case LTO_CODEGEN_PIC_MODEL_STATIC:
+    RelocModel = Reloc::Static;
+    break;
+  case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
+    RelocModel = Reloc::PIC_;
+    break;
+  case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
+    RelocModel = Reloc::DynamicNoPIC;
+    break;
+  }
+
+  // construct LTOModule, hand over ownership of module and target
+  SubtargetFeatures Features;
+  Features.getDefaultSubtargetFeatures(Triple);
+  std::string FeatureStr = Features.getString();
+  // Set a default CPU for Darwin triples.
+  if (MCpu.empty() && Triple.isOSDarwin()) {
+    if (Triple.getArch() == llvm::Triple::x86_64)
+      MCpu = "core2";
+    else if (Triple.getArch() == llvm::Triple::x86)
+      MCpu = "yonah";
+  }
+  TargetOptions Options;
+  LTOModule::getTargetOptions(Options);
+  TargetMach = march->createTargetMachine(TripleStr, MCpu, FeatureStr, Options,
+                                          RelocModel, CodeModel::Default,
+                                          CodeGenOpt::Aggressive);
+  return true;
+}
+
+void LTOCodeGenerator::
+applyRestriction(GlobalValue &GV,
+                 std::vector<const char*> &MustPreserveList,
+                 SmallPtrSet<GlobalValue*, 8> &AsmUsed,
+                 Mangler &Mangler) {
+  SmallString<64> Buffer;
+  Mangler.getNameWithPrefix(Buffer, &GV, false);
+
+  if (GV.isDeclaration())
+    return;
+  if (MustPreserveSymbols.count(Buffer))
+    MustPreserveList.push_back(GV.getName().data());
+  if (AsmUndefinedRefs.count(Buffer))
+    AsmUsed.insert(&GV);
+}
+
+static void findUsedValues(GlobalVariable *LLVMUsed,
+                           SmallPtrSet<GlobalValue*, 8> &UsedValues) {
+  if (LLVMUsed == 0) return;
+
+  ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
+  for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
+    if (GlobalValue *GV =
+        dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
+      UsedValues.insert(GV);
+}
+
+void LTOCodeGenerator::applyScopeRestrictions() {
+  if (ScopeRestrictionsDone)
+    return;
+  Module *mergedModule = Linker.getModule();
+
+  // Start off with a verification pass.
+  PassManager passes;
+  passes.add(createVerifierPass());
+
+  // mark which symbols can not be internalized
+  MCContext MContext(TargetMach->getMCAsmInfo(), TargetMach->getRegisterInfo(),
+                     NULL);
+  Mangler Mangler(MContext, TargetMach);
+  std::vector<const char*> MustPreserveList;
+  SmallPtrSet<GlobalValue*, 8> AsmUsed;
+
+  for (Module::iterator f = mergedModule->begin(),
+         e = mergedModule->end(); f != e; ++f)
+    applyRestriction(*f, MustPreserveList, AsmUsed, Mangler);
+  for (Module::global_iterator v = mergedModule->global_begin(),
+         e = mergedModule->global_end(); v !=  e; ++v)
+    applyRestriction(*v, MustPreserveList, AsmUsed, Mangler);
+  for (Module::alias_iterator a = mergedModule->alias_begin(),
+         e = mergedModule->alias_end(); a != e; ++a)
+    applyRestriction(*a, MustPreserveList, AsmUsed, Mangler);
+
+  GlobalVariable *LLVMCompilerUsed =
+    mergedModule->getGlobalVariable("llvm.compiler.used");
+  findUsedValues(LLVMCompilerUsed, AsmUsed);
+  if (LLVMCompilerUsed)
+    LLVMCompilerUsed->eraseFromParent();
+
+  if (!AsmUsed.empty()) {
+    llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(Context);
+    std::vector<Constant*> asmUsed2;
+    for (SmallPtrSet<GlobalValue*, 16>::const_iterator i = AsmUsed.begin(),
+           e = AsmUsed.end(); i !=e; ++i) {
+      GlobalValue *GV = *i;
+      Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
+      asmUsed2.push_back(c);
+    }
+
+    llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
+    LLVMCompilerUsed =
+      new llvm::GlobalVariable(*mergedModule, ATy, false,
+                               llvm::GlobalValue::AppendingLinkage,
+                               llvm::ConstantArray::get(ATy, asmUsed2),
+                               "llvm.compiler.used");
+
+    LLVMCompilerUsed->setSection("llvm.metadata");
+  }
+
+  passes.add(createInternalizePass(MustPreserveList));
+
+  // apply scope restrictions
+  passes.run(*mergedModule);
+
+  ScopeRestrictionsDone = true;
+}
+
+/// Optimize merged modules using various IPO passes
+bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
+                                          std::string &errMsg) {
+  if (!this->determineTarget(errMsg))
+    return false;
+
+  Module *mergedModule = Linker.getModule();
+
+  // Mark which symbols can not be internalized
+  this->applyScopeRestrictions();
+
+  // Instantiate the pass manager to organize the passes.
+  PassManager passes;
+
+  // Start off with a verification pass.
+  passes.add(createVerifierPass());
+
+  // Add an appropriate DataLayout instance for this module...
+  passes.add(new DataLayout(*TargetMach->getDataLayout()));
+  TargetMach->addAnalysisPasses(passes);
+
+  // Enabling internalize here would use its AllButMain variant. It
+  // keeps only main if it exists and does nothing for libraries. Instead
+  // we create the pass ourselves with the symbol list provided by the linker.
+  if (!DisableOpt)
+    PassManagerBuilder().populateLTOPassManager(passes,
+                                              /*Internalize=*/false,
+                                              !DisableInline,
+                                              DisableGVNLoadPRE);
+
+  // Make sure everything is still good.
+  passes.add(createVerifierPass());
+
+  PassManager codeGenPasses;
+
+  codeGenPasses.add(new DataLayout(*TargetMach->getDataLayout()));
+  TargetMach->addAnalysisPasses(codeGenPasses);
+
+  formatted_raw_ostream Out(out);
+
+  // If the bitcode files contain ARC code and were compiled with optimization,
+  // the ObjCARCContractPass must be run, so do it unconditionally here.
+  codeGenPasses.add(createObjCARCContractPass());
+
+  if (TargetMach->addPassesToEmitFile(codeGenPasses, Out,
+                                      TargetMachine::CGFT_ObjectFile)) {
+    errMsg = "target file type not supported";
+    return false;
+  }
+
+  // Run our queue of passes all at once now, efficiently.
+  passes.run(*mergedModule);
+
+  // Run the code generator, and write assembly file
+  codeGenPasses.run(*mergedModule);
+
+  return true;
+}
+
+/// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
+/// LTO problems.
+void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) {
+  for (std::pair<StringRef, StringRef> o = getToken(options);
+       !o.first.empty(); o = getToken(o.second)) {
+    // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add
+    // that.
+    if (CodegenOptions.empty())
+      CodegenOptions.push_back(strdup("libLLVMLTO"));
+    CodegenOptions.push_back(strdup(o.first.str().c_str()));
+  }
+}