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//===--- Backend.cpp - Interface to LLVM backend technologies -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "clang/Frontend/ASTConsumers.h"
#include "clang/CodeGen/ModuleBuilder.h"
#include "clang/Frontend/CompileOptions.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/DeclGroup.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/Module.h"
#include "llvm/ModuleProvider.h"
#include "llvm/PassManager.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/Assembly/PrintModulePass.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/CodeGen/RegAllocRegistry.h"
#include "llvm/CodeGen/SchedulerRegistry.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Timer.h"
#include "llvm/System/Path.h"
#include "llvm/System/Program.h"
#include "llvm/Target/SubtargetFeature.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetMachineRegistry.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/IPO.h"
using namespace clang;
using namespace llvm;
namespace {
class VISIBILITY_HIDDEN BackendConsumer : public ASTConsumer {
BackendAction Action;
CompileOptions CompileOpts;
llvm::raw_ostream *AsmOutStream;
ASTContext *Context;
Timer LLVMIRGeneration;
Timer CodeGenerationTime;
llvm::OwningPtr<CodeGenerator> Gen;
llvm::Module *TheModule;
llvm::TargetData *TheTargetData;
mutable llvm::ModuleProvider *ModuleProvider;
mutable FunctionPassManager *CodeGenPasses;
mutable PassManager *PerModulePasses;
mutable FunctionPassManager *PerFunctionPasses;
FunctionPassManager *getCodeGenPasses() const;
PassManager *getPerModulePasses() const;
FunctionPassManager *getPerFunctionPasses() const;
void CreatePasses();
/// AddEmitPasses - Add passes necessary to emit assembly or LLVM
/// IR.
///
/// \return True on success. On failure \arg Error will be set to
/// a user readable error message.
bool AddEmitPasses(std::string &Error);
void EmitAssembly();
public:
BackendConsumer(BackendAction action, Diagnostic &Diags,
const LangOptions &langopts, const CompileOptions &compopts,
const std::string &infile, llvm::raw_ostream* OS) :
Action(action),
CompileOpts(compopts),
AsmOutStream(OS),
LLVMIRGeneration("LLVM IR Generation Time"),
CodeGenerationTime("Code Generation Time"),
Gen(CreateLLVMCodeGen(Diags, infile, compopts)),
TheModule(0), TheTargetData(0), ModuleProvider(0),
CodeGenPasses(0), PerModulePasses(0), PerFunctionPasses(0) {
// Enable -time-passes if -ftime-report is enabled.
llvm::TimePassesIsEnabled = CompileOpts.TimePasses;
}
~BackendConsumer() {
delete TheTargetData;
delete ModuleProvider;
delete CodeGenPasses;
delete PerModulePasses;
delete PerFunctionPasses;
}
virtual void Initialize(ASTContext &Ctx) {
Context = &Ctx;
if (CompileOpts.TimePasses)
LLVMIRGeneration.startTimer();
Gen->Initialize(Ctx);
TheModule = Gen->GetModule();
ModuleProvider = new ExistingModuleProvider(TheModule);
TheTargetData = new llvm::TargetData(Ctx.Target.getTargetDescription());
if (CompileOpts.TimePasses)
LLVMIRGeneration.stopTimer();
}
virtual void HandleTopLevelDecl(DeclGroupRef D) {
PrettyStackTraceDecl CrashInfo(*D.begin(), SourceLocation(),
Context->getSourceManager(),
"LLVM IR generation of declaration");
if (CompileOpts.TimePasses)
LLVMIRGeneration.startTimer();
Gen->HandleTopLevelDecl(D);
if (CompileOpts.TimePasses)
LLVMIRGeneration.stopTimer();
}
virtual void HandleTranslationUnit(ASTContext &C) {
{
PrettyStackTraceString CrashInfo("Per-file LLVM IR generation");
if (CompileOpts.TimePasses)
LLVMIRGeneration.startTimer();
Gen->HandleTranslationUnit(C);
if (CompileOpts.TimePasses)
LLVMIRGeneration.stopTimer();
}
// EmitAssembly times and registers crash info itself.
EmitAssembly();
// Force a flush here in case we never get released.
if (AsmOutStream)
AsmOutStream->flush();
}
virtual void HandleTagDeclDefinition(TagDecl *D) {
PrettyStackTraceDecl CrashInfo(D, SourceLocation(),
Context->getSourceManager(),
"LLVM IR generation of declaration");
Gen->HandleTagDeclDefinition(D);
}
virtual void CompleteTentativeDefinition(VarDecl *D) {
Gen->CompleteTentativeDefinition(D);
}
};
}
FunctionPassManager *BackendConsumer::getCodeGenPasses() const {
if (!CodeGenPasses) {
CodeGenPasses = new FunctionPassManager(ModuleProvider);
CodeGenPasses->add(new TargetData(*TheTargetData));
}
return CodeGenPasses;
}
PassManager *BackendConsumer::getPerModulePasses() const {
if (!PerModulePasses) {
PerModulePasses = new PassManager();
PerModulePasses->add(new TargetData(*TheTargetData));
}
return PerModulePasses;
}
FunctionPassManager *BackendConsumer::getPerFunctionPasses() const {
if (!PerFunctionPasses) {
PerFunctionPasses = new FunctionPassManager(ModuleProvider);
PerFunctionPasses->add(new TargetData(*TheTargetData));
}
return PerFunctionPasses;
}
bool BackendConsumer::AddEmitPasses(std::string &Error) {
if (Action == Backend_EmitNothing)
return true;
if (Action == Backend_EmitBC) {
getPerModulePasses()->add(createBitcodeWriterPass(*AsmOutStream));
} else if (Action == Backend_EmitLL) {
getPerModulePasses()->add(createPrintModulePass(AsmOutStream));
} else {
bool Fast = CompileOpts.OptimizationLevel == 0;
// Create the TargetMachine for generating code.
const TargetMachineRegistry::entry *TME =
TargetMachineRegistry::getClosestStaticTargetForModule(*TheModule, Error);
if (!TME) {
Error = std::string("Unable to get target machine: ") + Error;
return false;
}
std::string FeaturesStr;
if (CompileOpts.CPU.size() || CompileOpts.Features.size()) {
SubtargetFeatures Features;
Features.setCPU(CompileOpts.CPU);
for (std::vector<std::string>::iterator
it = CompileOpts.Features.begin(),
ie = CompileOpts.Features.end(); it != ie; ++it)
Features.AddFeature(*it);
FeaturesStr = Features.getString();
}
TargetMachine *TM = TME->CtorFn(*TheModule, FeaturesStr);
// Set register scheduler & allocation policy.
RegisterScheduler::setDefault(createDefaultScheduler);
RegisterRegAlloc::setDefault(Fast ? createLocalRegisterAllocator :
createLinearScanRegisterAllocator);
// From llvm-gcc:
// If there are passes we have to run on the entire module, we do codegen
// as a separate "pass" after that happens.
// FIXME: This is disabled right now until bugs can be worked out. Reenable
// this for fast -O0 compiles!
FunctionPassManager *PM = getCodeGenPasses();
CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
switch (CompileOpts.OptimizationLevel) {
default: break;
case 0: OptLevel = CodeGenOpt::None; break;
case 3: OptLevel = CodeGenOpt::Aggressive; break;
}
// Normal mode, emit a .s file by running the code generator.
// Note, this also adds codegenerator level optimization passes.
switch (TM->addPassesToEmitFile(*PM, *AsmOutStream,
TargetMachine::AssemblyFile, OptLevel)) {
default:
case FileModel::Error:
Error = "Unable to interface with target machine!\n";
return false;
case FileModel::AsmFile:
break;
}
if (TM->addPassesToEmitFileFinish(*CodeGenPasses, 0, OptLevel)) {
Error = "Unable to interface with target machine!\n";
return false;
}
}
return true;
}
void BackendConsumer::CreatePasses() {
// In -O0 if checking is disabled, we don't even have per-function passes.
if (CompileOpts.VerifyModule)
getPerFunctionPasses()->add(createVerifierPass());
if (CompileOpts.OptimizationLevel > 0) {
FunctionPassManager *PM = getPerFunctionPasses();
PM->add(createCFGSimplificationPass());
if (CompileOpts.OptimizationLevel == 1)
PM->add(createPromoteMemoryToRegisterPass());
else
PM->add(createScalarReplAggregatesPass());
PM->add(createInstructionCombiningPass());
}
// For now we always create per module passes.
PassManager *PM = getPerModulePasses();
if (CompileOpts.OptimizationLevel > 0) {
if (CompileOpts.UnitAtATime)
PM->add(createRaiseAllocationsPass()); // call %malloc -> malloc inst
PM->add(createCFGSimplificationPass()); // Clean up disgusting code
PM->add(createPromoteMemoryToRegisterPass()); // Kill useless allocas
if (CompileOpts.UnitAtATime) {
PM->add(createGlobalOptimizerPass()); // Optimize out global vars
PM->add(createGlobalDCEPass()); // Remove unused fns and globs
PM->add(createIPConstantPropagationPass()); // IP Constant Propagation
PM->add(createDeadArgEliminationPass()); // Dead argument elimination
}
PM->add(createInstructionCombiningPass()); // Clean up after IPCP & DAE
PM->add(createCFGSimplificationPass()); // Clean up after IPCP & DAE
if (CompileOpts.UnitAtATime) {
PM->add(createPruneEHPass()); // Remove dead EH info
PM->add(createFunctionAttrsPass()); // Set readonly/readnone attrs
}
if (CompileOpts.InlineFunctions)
PM->add(createFunctionInliningPass()); // Inline small functions
else
PM->add(createAlwaysInlinerPass()); // Respect always_inline
if (CompileOpts.OptimizationLevel > 2)
PM->add(createArgumentPromotionPass()); // Scalarize uninlined fn args
if (CompileOpts.SimplifyLibCalls)
PM->add(createSimplifyLibCallsPass()); // Library Call Optimizations
PM->add(createInstructionCombiningPass()); // Cleanup for scalarrepl.
PM->add(createJumpThreadingPass()); // Thread jumps.
PM->add(createCFGSimplificationPass()); // Merge & remove BBs
PM->add(createScalarReplAggregatesPass()); // Break up aggregate allocas
PM->add(createInstructionCombiningPass()); // Combine silly seq's
PM->add(createCondPropagationPass()); // Propagate conditionals
PM->add(createTailCallEliminationPass()); // Eliminate tail calls
PM->add(createCFGSimplificationPass()); // Merge & remove BBs
PM->add(createReassociatePass()); // Reassociate expressions
PM->add(createLoopRotatePass()); // Rotate Loop
PM->add(createLICMPass()); // Hoist loop invariants
PM->add(createLoopUnswitchPass(CompileOpts.OptimizeSize ? true : false));
// PM->add(createLoopIndexSplitPass()); // Split loop index
PM->add(createInstructionCombiningPass());
PM->add(createIndVarSimplifyPass()); // Canonicalize indvars
PM->add(createLoopDeletionPass()); // Delete dead loops
if (CompileOpts.UnrollLoops)
PM->add(createLoopUnrollPass()); // Unroll small loops
PM->add(createInstructionCombiningPass()); // Clean up after the unroller
PM->add(createGVNPass()); // Remove redundancies
PM->add(createMemCpyOptPass()); // Remove memcpy / form memset
PM->add(createSCCPPass()); // Constant prop with SCCP
// Run instcombine after redundancy elimination to exploit opportunities
// opened up by them.
PM->add(createInstructionCombiningPass());
PM->add(createCondPropagationPass()); // Propagate conditionals
PM->add(createDeadStoreEliminationPass()); // Delete dead stores
PM->add(createAggressiveDCEPass()); // Delete dead instructions
PM->add(createCFGSimplificationPass()); // Merge & remove BBs
if (CompileOpts.UnitAtATime) {
PM->add(createStripDeadPrototypesPass()); // Get rid of dead prototypes
PM->add(createDeadTypeEliminationPass()); // Eliminate dead types
}
if (CompileOpts.OptimizationLevel > 1 && CompileOpts.UnitAtATime)
PM->add(createConstantMergePass()); // Merge dup global constants
} else {
PM->add(createAlwaysInlinerPass());
}
}
/// EmitAssembly - Handle interaction with LLVM backend to generate
/// actual machine code.
void BackendConsumer::EmitAssembly() {
// Silently ignore if we weren't initialized for some reason.
if (!TheModule || !TheTargetData)
return;
TimeRegion Region(CompileOpts.TimePasses ? &CodeGenerationTime : 0);
// Make sure IR generation is happy with the module. This is
// released by the module provider.
Module *M = Gen->ReleaseModule();
if (!M) {
// The module has been released by IR gen on failures, do not
// double free.
ModuleProvider->releaseModule();
TheModule = 0;
return;
}
assert(TheModule == M && "Unexpected module change during IR generation");
CreatePasses();
std::string Error;
if (!AddEmitPasses(Error)) {
// FIXME: Don't fail this way.
llvm::cerr << "ERROR: " << Error << "\n";
::exit(1);
}
// Run passes. For now we do all passes at once, but eventually we
// would like to have the option of streaming code generation.
if (PerFunctionPasses) {
PrettyStackTraceString CrashInfo("Per-function optimization");
PerFunctionPasses->doInitialization();
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (!I->isDeclaration())
PerFunctionPasses->run(*I);
PerFunctionPasses->doFinalization();
}
if (PerModulePasses) {
PrettyStackTraceString CrashInfo("Per-module optimization passes");
PerModulePasses->run(*M);
}
if (CodeGenPasses) {
PrettyStackTraceString CrashInfo("Code generation");
CodeGenPasses->doInitialization();
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (!I->isDeclaration())
CodeGenPasses->run(*I);
CodeGenPasses->doFinalization();
}
}
ASTConsumer *clang::CreateBackendConsumer(BackendAction Action,
Diagnostic &Diags,
const LangOptions &LangOpts,
const CompileOptions &CompileOpts,
const std::string& InFile,
llvm::raw_ostream* OS) {
return new BackendConsumer(Action, Diags, LangOpts, CompileOpts, InFile, OS);
}