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llvm-6502/lib/LTO/LTOCodeGenerator.cpp
Peter Collingbourne 3fcf5a99cb Make the C++ LTO API easier to use from C++ clients. 
Start using C++ types such as StringRef and MemoryBuffer in the C++ LTO
API. In doing so, clarify the ownership of the native object file: the caller
now owns it, not the LTOCodeGenerator. The C libLTO library has been modified
to use a derived class of LTOCodeGenerator that owns the object file.

Differential Revision: http://reviews.llvm.org/D10114

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238776 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-01 20:08:30 +00:00

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//===-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/ADT/StringExtras.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/Config/config.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/InitializePasses.h"
#include "llvm/LTO/LTOModule.h"
#include "llvm/Linker/Linker.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.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/raw_ostream.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Transforms/ObjCARC.h"
#include <system_error>
using namespace llvm;
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()), IRLinker(new Module("ld-temp.o", Context)) {
initializeLTOPasses();
}
LTOCodeGenerator::LTOCodeGenerator(std::unique_ptr<LLVMContext> Context)
: OwnedContext(std::move(Context)), Context(*OwnedContext),
IRLinker(new Module("ld-temp.o", *OwnedContext)) {
initializeLTOPasses();
}
void LTOCodeGenerator::destroyMergedModule() {
if (OwnedModule) {
assert(IRLinker.getModule() == &OwnedModule->getModule() &&
"The linker's module should be the same as the owned module");
delete OwnedModule;
OwnedModule = nullptr;
} else if (IRLinker.getModule())
IRLinker.deleteModule();
}
LTOCodeGenerator::~LTOCodeGenerator() {
destroyMergedModule();
delete TargetMach;
TargetMach = nullptr;
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);
initializeInstructionCombiningPassPass(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);
initializeMergedLoadStoreMotionPass(R);
initializeGVNPass(R);
initializeMemCpyOptPass(R);
initializeDCEPass(R);
initializeCFGSimplifyPassPass(R);
}
bool LTOCodeGenerator::addModule(LTOModule *mod) {
assert(&mod->getModule().getContext() == &Context &&
"Expected module in same context");
bool ret = IRLinker.linkInModule(&mod->getModule());
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::setModule(LTOModule *Mod) {
assert(&Mod->getModule().getContext() == &Context &&
"Expected module in same context");
// Delete the old merged module.
destroyMergedModule();
AsmUndefinedRefs.clear();
OwnedModule = Mod;
IRLinker.setModule(&Mod->getModule());
const std::vector<const char*> &Undefs = Mod->getAsmUndefinedRefs();
for (int I = 0, E = Undefs.size(); I != E; ++I)
AsmUndefinedRefs[Undefs[I]] = 1;
}
void LTOCodeGenerator::setTargetOptions(TargetOptions options) {
Options = options;
}
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:
case LTO_CODEGEN_PIC_MODEL_DEFAULT:
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::error_code EC;
tool_output_file Out(path, EC, sys::fs::F_None);
if (EC) {
errMsg = "could not open bitcode file for writing: ";
errMsg += path;
return false;
}
// write bitcode to it
WriteBitcodeToFile(IRLinker.getModule(), Out.os(), ShouldEmbedUselists);
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::compileOptimizedToFile(const char **name,
std::string &errMsg) {
// make unique temp .o file to put generated object file
SmallString<128> Filename;
int FD;
std::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 = compileOptimized(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;
}
std::unique_ptr<MemoryBuffer>
LTOCodeGenerator::compileOptimized(std::string &errMsg) {
const char *name;
if (!compileOptimizedToFile(&name, errMsg))
return nullptr;
// read .o file into memory buffer
ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
MemoryBuffer::getFile(name, -1, false);
if (std::error_code EC = BufferOrErr.getError()) {
errMsg = EC.message();
sys::fs::remove(NativeObjectPath);
return nullptr;
}
// remove temp files
sys::fs::remove(NativeObjectPath);
return std::move(*BufferOrErr);
}
bool LTOCodeGenerator::compile_to_file(const char **name,
bool disableInline,
bool disableGVNLoadPRE,
bool disableVectorization,
std::string &errMsg) {
if (!optimize(disableInline, disableGVNLoadPRE,
disableVectorization, errMsg))
return false;
return compileOptimizedToFile(name, errMsg);
}
std::unique_ptr<MemoryBuffer>
LTOCodeGenerator::compile(bool disableInline, bool disableGVNLoadPRE,
bool disableVectorization, std::string &errMsg) {
if (!optimize(disableInline, disableGVNLoadPRE,
disableVectorization, errMsg))
return nullptr;
return compileOptimized(errMsg);
}
bool LTOCodeGenerator::determineTarget(std::string &errMsg) {
if (TargetMach)
return true;
std::string TripleStr = IRLinker.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)
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;
case LTO_CODEGEN_PIC_MODEL_DEFAULT:
// RelocModel is already the default, so leave it that way.
break;
}
// Construct LTOModule, hand over ownership of module and target. Use MAttr as
// the default set of features.
SubtargetFeatures Features(MAttr);
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";
else if (Triple.getArch() == llvm::Triple::aarch64)
MCpu = "cyclone";
}
CodeGenOpt::Level CGOptLevel;
switch (OptLevel) {
case 0:
CGOptLevel = CodeGenOpt::None;
break;
case 1:
CGOptLevel = CodeGenOpt::Less;
break;
case 2:
CGOptLevel = CodeGenOpt::Default;
break;
case 3:
CGOptLevel = CodeGenOpt::Aggressive;
break;
}
TargetMach = march->createTargetMachine(TripleStr, MCpu, FeatureStr, Options,
RelocModel, CodeModel::Default,
CGOptLevel);
return true;
}
void LTOCodeGenerator::
applyRestriction(GlobalValue &GV,
ArrayRef<StringRef> Libcalls,
std::vector<const char*> &MustPreserveList,
SmallPtrSetImpl<GlobalValue*> &AsmUsed,
Mangler &Mangler) {
// There are no restrictions to apply to declarations.
if (GV.isDeclaration())
return;
// There is nothing more restrictive than private linkage.
if (GV.hasPrivateLinkage())
return;
SmallString<64> Buffer;
TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);
if (MustPreserveSymbols.count(Buffer))
MustPreserveList.push_back(GV.getName().data());
if (AsmUndefinedRefs.count(Buffer))
AsmUsed.insert(&GV);
// Conservatively append user-supplied runtime library functions to
// llvm.compiler.used. These could be internalized and deleted by
// optimizations like -globalopt, causing problems when later optimizations
// add new library calls (e.g., llvm.memset => memset and printf => puts).
// Leave it to the linker to remove any dead code (e.g. with -dead_strip).
if (isa<Function>(GV) &&
std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
AsmUsed.insert(&GV);
}
static void findUsedValues(GlobalVariable *LLVMUsed,
SmallPtrSetImpl<GlobalValue*> &UsedValues) {
if (!LLVMUsed) 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);
}
// Collect names of runtime library functions. User-defined functions with the
// same names are added to llvm.compiler.used to prevent them from being
// deleted by optimizations.
static void accumulateAndSortLibcalls(std::vector<StringRef> &Libcalls,
const TargetLibraryInfo& TLI,
const Module &Mod,
const TargetMachine &TM) {
// TargetLibraryInfo has info on C runtime library calls on the current
// target.
for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
I != E; ++I) {
LibFunc::Func F = static_cast<LibFunc::Func>(I);
if (TLI.has(F))
Libcalls.push_back(TLI.getName(F));
}
SmallPtrSet<const TargetLowering *, 1> TLSet;
for (const Function &F : Mod) {
const TargetLowering *Lowering =
TM.getSubtargetImpl(F)->getTargetLowering();
if (Lowering && TLSet.insert(Lowering).second)
// TargetLowering has info on library calls that CodeGen expects to be
// available, both from the C runtime and compiler-rt.
for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
I != E; ++I)
if (const char *Name =
Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
Libcalls.push_back(Name);
}
array_pod_sort(Libcalls.begin(), Libcalls.end());
Libcalls.erase(std::unique(Libcalls.begin(), Libcalls.end()),
Libcalls.end());
}
void LTOCodeGenerator::applyScopeRestrictions() {
if (ScopeRestrictionsDone || !ShouldInternalize)
return;
Module *mergedModule = IRLinker.getModule();
// Start off with a verification pass.
legacy::PassManager passes;
passes.add(createVerifierPass());
// mark which symbols can not be internalized
Mangler Mangler(TargetMach->getDataLayout());
std::vector<const char*> MustPreserveList;
SmallPtrSet<GlobalValue*, 8> AsmUsed;
std::vector<StringRef> Libcalls;
TargetLibraryInfoImpl TLII(Triple(TargetMach->getTargetTriple()));
TargetLibraryInfo TLI(TLII);
accumulateAndSortLibcalls(Libcalls, TLI, *mergedModule, *TargetMach);
for (Module::iterator f = mergedModule->begin(),
e = mergedModule->end(); f != e; ++f)
applyRestriction(*f, Libcalls, MustPreserveList, AsmUsed, Mangler);
for (Module::global_iterator v = mergedModule->global_begin(),
e = mergedModule->global_end(); v != e; ++v)
applyRestriction(*v, Libcalls, MustPreserveList, AsmUsed, Mangler);
for (Module::alias_iterator a = mergedModule->alias_begin(),
e = mergedModule->alias_end(); a != e; ++a)
applyRestriction(*a, Libcalls, 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 (auto *GV : AsmUsed) {
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::optimize(bool DisableInline,
bool DisableGVNLoadPRE,
bool DisableVectorization,
std::string &errMsg) {
if (!this->determineTarget(errMsg))
return false;
Module *mergedModule = IRLinker.getModule();
// Mark which symbols can not be internalized
this->applyScopeRestrictions();
// Instantiate the pass manager to organize the passes.
legacy::PassManager passes;
// Add an appropriate DataLayout instance for this module...
mergedModule->setDataLayout(*TargetMach->getDataLayout());
passes.add(
createTargetTransformInfoWrapperPass(TargetMach->getTargetIRAnalysis()));
Triple TargetTriple(TargetMach->getTargetTriple());
PassManagerBuilder PMB;
PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
PMB.LoopVectorize = !DisableVectorization;
PMB.SLPVectorize = !DisableVectorization;
if (!DisableInline)
PMB.Inliner = createFunctionInliningPass();
PMB.LibraryInfo = new TargetLibraryInfoImpl(TargetTriple);
PMB.OptLevel = OptLevel;
PMB.VerifyInput = true;
PMB.VerifyOutput = true;
PMB.populateLTOPassManager(passes);
// Run our queue of passes all at once now, efficiently.
passes.run(*mergedModule);
return true;
}
bool LTOCodeGenerator::compileOptimized(raw_pwrite_stream &out,
std::string &errMsg) {
if (!this->determineTarget(errMsg))
return false;
Module *mergedModule = IRLinker.getModule();
legacy::PassManager codeGenPasses;
// 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 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()));
}
}
void LTOCodeGenerator::parseCodeGenDebugOptions() {
// if options were requested, set them
if (!CodegenOptions.empty())
cl::ParseCommandLineOptions(CodegenOptions.size(),
const_cast<char **>(&CodegenOptions[0]));
}
void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI,
void *Context) {
((LTOCodeGenerator *)Context)->DiagnosticHandler2(DI);
}
void LTOCodeGenerator::DiagnosticHandler2(const DiagnosticInfo &DI) {
// Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
lto_codegen_diagnostic_severity_t Severity;
switch (DI.getSeverity()) {
case DS_Error:
Severity = LTO_DS_ERROR;
break;
case DS_Warning:
Severity = LTO_DS_WARNING;
break;
case DS_Remark:
Severity = LTO_DS_REMARK;
break;
case DS_Note:
Severity = LTO_DS_NOTE;
break;
}
// Create the string that will be reported to the external diagnostic handler.
std::string MsgStorage;
raw_string_ostream Stream(MsgStorage);
DiagnosticPrinterRawOStream DP(Stream);
DI.print(DP);
Stream.flush();
// If this method has been called it means someone has set up an external
// diagnostic handler. Assert on that.
assert(DiagHandler && "Invalid diagnostic handler");
(*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
}
void
LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
void *Ctxt) {
this->DiagHandler = DiagHandler;
this->DiagContext = Ctxt;
if (!DiagHandler)
return Context.setDiagnosticHandler(nullptr, nullptr);
// Register the LTOCodeGenerator stub in the LLVMContext to forward the
// diagnostic to the external DiagHandler.
Context.setDiagnosticHandler(LTOCodeGenerator::DiagnosticHandler, this,
/* RespectFilters */ true);
}
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