lib/Frontend/CodeGenAction.cpp

//===--- CodeGenAction.cpp - LLVM Code Generation Frontend Action ---------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "clang/Frontend/CodeGenAction.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclGroup.h"
#include "clang/CodeGen/ModuleBuilder.h"
#include "clang/Frontend/ASTConsumers.h"
#include "clang/Frontend/BackendUtil.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/FrontendDiagnostic.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/Support/IRReader.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/Timer.h"
using namespace clang;
using namespace llvm;

namespace {
  class BackendConsumer : public ASTConsumer {
    Diagnostic &Diags;
    BackendAction Action;
    const CodeGenOptions &CodeGenOpts;
    const TargetOptions &TargetOpts;
    llvm::raw_ostream *AsmOutStream;
    ASTContext *Context;

    Timer LLVMIRGeneration;

    llvm::OwningPtr<CodeGenerator> Gen;

    llvm::OwningPtr<llvm::Module> TheModule;

  public:
    BackendConsumer(BackendAction action, Diagnostic &_Diags,
                    const CodeGenOptions &compopts,
                    const TargetOptions &targetopts, bool TimePasses,
                    const std::string &infile, llvm::raw_ostream *OS,
                    LLVMContext &C) :
      Diags(_Diags),
      Action(action),
      CodeGenOpts(compopts),
      TargetOpts(targetopts),
      AsmOutStream(OS),
      LLVMIRGeneration("LLVM IR Generation Time"),
      Gen(CreateLLVMCodeGen(Diags, infile, compopts, C)) {
      llvm::TimePassesIsEnabled = TimePasses;
    }

    llvm::Module *takeModule() { return TheModule.take(); }

    virtual void Initialize(ASTContext &Ctx) {
      Context = &Ctx;

      if (llvm::TimePassesIsEnabled)
        LLVMIRGeneration.startTimer();

      Gen->Initialize(Ctx);

      TheModule.reset(Gen->GetModule());

      if (llvm::TimePassesIsEnabled)
        LLVMIRGeneration.stopTimer();
    }

    virtual void HandleTopLevelDecl(DeclGroupRef D) {
      PrettyStackTraceDecl CrashInfo(*D.begin(), SourceLocation(),
                                     Context->getSourceManager(),
                                     "LLVM IR generation of declaration");

      if (llvm::TimePassesIsEnabled)
        LLVMIRGeneration.startTimer();

      Gen->HandleTopLevelDecl(D);

      if (llvm::TimePassesIsEnabled)
        LLVMIRGeneration.stopTimer();
    }

    virtual void HandleTranslationUnit(ASTContext &C) {
      {
        PrettyStackTraceString CrashInfo("Per-file LLVM IR generation");
        if (llvm::TimePassesIsEnabled)
          LLVMIRGeneration.startTimer();

        Gen->HandleTranslationUnit(C);

        if (llvm::TimePassesIsEnabled)
          LLVMIRGeneration.stopTimer();
      }

      // Silently ignore if we weren't initialized for some reason.
      if (!TheModule)
        return;

      // 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.
        TheModule.take();
        return;
      }

      assert(TheModule.get() == M &&
             "Unexpected module change during IR generation");

      // Install an inline asm handler so that diagnostics get printed through
      // our diagnostics hooks.
      LLVMContext &Ctx = TheModule->getContext();
      void *OldHandler = Ctx.getInlineAsmDiagnosticHandler();
      void *OldContext = Ctx.getInlineAsmDiagnosticContext();
      Ctx.setInlineAsmDiagnosticHandler((void*)(intptr_t)InlineAsmDiagHandler,
                                        this);

      EmitBackendOutput(Diags, CodeGenOpts, TargetOpts,
                        TheModule.get(), Action, AsmOutStream);
      
      Ctx.setInlineAsmDiagnosticHandler(OldHandler, OldContext);
    }

    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);
    }

    virtual void HandleVTable(CXXRecordDecl *RD, bool DefinitionRequired) {
      Gen->HandleVTable(RD, DefinitionRequired);
    }

    static void InlineAsmDiagHandler(const llvm::SMDiagnostic &SM,void *Context,
                                     unsigned LocCookie) {
      SourceLocation Loc = SourceLocation::getFromRawEncoding(LocCookie);
      ((BackendConsumer*)Context)->InlineAsmDiagHandler2(SM, Loc);
    }

    void InlineAsmDiagHandler2(const llvm::SMDiagnostic &,
                               SourceLocation LocCookie);
  };
}

/// ConvertBackendLocation - Convert a location in a temporary llvm::SourceMgr
/// buffer to be a valid FullSourceLoc.
static FullSourceLoc ConvertBackendLocation(const llvm::SMDiagnostic &D,
                                            SourceManager &CSM) {
  // Get both the clang and llvm source managers.  The location is relative to
  // a memory buffer that the LLVM Source Manager is handling, we need to add
  // a copy to the Clang source manager.
  const llvm::SourceMgr &LSM = *D.getSourceMgr();

  // We need to copy the underlying LLVM memory buffer because llvm::SourceMgr
  // already owns its one and clang::SourceManager wants to own its one.
  const MemoryBuffer *LBuf =
  LSM.getMemoryBuffer(LSM.FindBufferContainingLoc(D.getLoc()));

  // Create the copy and transfer ownership to clang::SourceManager.
  llvm::MemoryBuffer *CBuf =
  llvm::MemoryBuffer::getMemBufferCopy(LBuf->getBuffer(),
                                       LBuf->getBufferIdentifier());
  FileID FID = CSM.createFileIDForMemBuffer(CBuf);

  // Translate the offset into the file.
  unsigned Offset = D.getLoc().getPointer()  - LBuf->getBufferStart();
  SourceLocation NewLoc =
  CSM.getLocForStartOfFile(FID).getFileLocWithOffset(Offset);
  return FullSourceLoc(NewLoc, CSM);
}


/// InlineAsmDiagHandler2 - This function is invoked when the backend hits an
/// error parsing inline asm.  The SMDiagnostic indicates the error relative to
/// the temporary memory buffer that the inline asm parser has set up.
void BackendConsumer::InlineAsmDiagHandler2(const llvm::SMDiagnostic &D,
                                            SourceLocation LocCookie) {
  // There are a couple of different kinds of errors we could get here.  First,
  // we re-format the SMDiagnostic in terms of a clang diagnostic.

  // Strip "error: " off the start of the message string.
  llvm::StringRef Message = D.getMessage();
  if (Message.startswith("error: "))
    Message = Message.substr(7);

  // There are two cases: the SMDiagnostic could have a inline asm source
  // location or it might not.  If it does, translate the location.
  FullSourceLoc Loc;
  if (D.getLoc() != SMLoc())
    Loc = ConvertBackendLocation(D, Context->getSourceManager());
  Diags.Report(Loc, diag::err_fe_inline_asm).AddString(Message);

  // This could be a problem with no clang-level source location information.
  // In this case, LocCookie is invalid.  If there is source level information,
  // print an "generated from" note.
  if (LocCookie.isValid())
    Diags.Report(FullSourceLoc(LocCookie, Context->getSourceManager()),
                 diag::note_fe_inline_asm_here);
}

//

CodeGenAction::CodeGenAction(unsigned _Act) : Act(_Act) {}

CodeGenAction::~CodeGenAction() {}

bool CodeGenAction::hasIRSupport() const { return true; }

void CodeGenAction::EndSourceFileAction() {
  // If the consumer creation failed, do nothing.
  if (!getCompilerInstance().hasASTConsumer())
    return;

  // Steal the module from the consumer.
  BackendConsumer *Consumer = static_cast<BackendConsumer*>(
    &getCompilerInstance().getASTConsumer());

  TheModule.reset(Consumer->takeModule());
}

llvm::Module *CodeGenAction::takeModule() {
  return TheModule.take();
}

static raw_ostream *GetOutputStream(CompilerInstance &CI,
                                    llvm::StringRef InFile,
                                    BackendAction Action) {
  switch (Action) {
  case Backend_EmitAssembly:
    return CI.createDefaultOutputFile(false, InFile, "s");
  case Backend_EmitLL:
    return CI.createDefaultOutputFile(false, InFile, "ll");
  case Backend_EmitBC:
    return CI.createDefaultOutputFile(true, InFile, "bc");
  case Backend_EmitNothing:
    return 0;
  case Backend_EmitMCNull:
  case Backend_EmitObj:
    return CI.createDefaultOutputFile(true, InFile, "o");
  }

  assert(0 && "Invalid action!");
  return 0;
}

ASTConsumer *CodeGenAction::CreateASTConsumer(CompilerInstance &CI,
                                              llvm::StringRef InFile) {
  BackendAction BA = static_cast<BackendAction>(Act);
  llvm::OwningPtr<llvm::raw_ostream> OS(GetOutputStream(CI, InFile, BA));
  if (BA != Backend_EmitNothing && !OS)
    return 0;

  return new BackendConsumer(BA, CI.getDiagnostics(),
                             CI.getCodeGenOpts(), CI.getTargetOpts(),
                             CI.getFrontendOpts().ShowTimers, InFile, OS.take(),
                             CI.getLLVMContext());
}

void CodeGenAction::ExecuteAction() {
  // If this is an IR file, we have to treat it specially.
  if (getCurrentFileKind() == IK_LLVM_IR) {
    BackendAction BA = static_cast<BackendAction>(Act);
    CompilerInstance &CI = getCompilerInstance();
    raw_ostream *OS = GetOutputStream(CI, getCurrentFile(), BA);
    if (BA != Backend_EmitNothing && !OS)
      return;

    bool Invalid;
    SourceManager &SM = CI.getSourceManager();
    const llvm::MemoryBuffer *MainFile = SM.getBuffer(SM.getMainFileID(),
                                                      &Invalid);
    if (Invalid)
      return;

    // FIXME: This is stupid, IRReader shouldn't take ownership.
    llvm::MemoryBuffer *MainFileCopy =
      llvm::MemoryBuffer::getMemBufferCopy(MainFile->getBuffer(),
                                           getCurrentFile().c_str());

    llvm::SMDiagnostic Err;
    TheModule.reset(ParseIR(MainFileCopy, Err, CI.getLLVMContext()));
    if (!TheModule) {
      // Translate from the diagnostic info to the SourceManager location.
      SourceLocation Loc = SM.getLocation(
        SM.getFileEntryForID(SM.getMainFileID()), Err.getLineNo(),
        Err.getColumnNo() + 1);

      // Get a custom diagnostic for the error. We strip off a leading
      // diagnostic code if there is one.
      llvm::StringRef Msg = Err.getMessage();
      if (Msg.startswith("error: "))
        Msg = Msg.substr(7);
      unsigned DiagID = CI.getDiagnostics().getCustomDiagID(Diagnostic::Error,
                                                            Msg);

      CI.getDiagnostics().Report(FullSourceLoc(Loc, SM), DiagID);
      return;
    }

    EmitBackendOutput(CI.getDiagnostics(), CI.getCodeGenOpts(),
                      CI.getTargetOpts(), TheModule.get(),
                      BA, OS);
    return;
  }

  // Otherwise follow the normal AST path.
  this->ASTFrontendAction::ExecuteAction();
}

//

EmitAssemblyAction::EmitAssemblyAction()
  : CodeGenAction(Backend_EmitAssembly) {}

EmitBCAction::EmitBCAction() : CodeGenAction(Backend_EmitBC) {}

EmitLLVMAction::EmitLLVMAction() : CodeGenAction(Backend_EmitLL) {}

EmitLLVMOnlyAction::EmitLLVMOnlyAction() : CodeGenAction(Backend_EmitNothing) {}

EmitCodeGenOnlyAction::EmitCodeGenOnlyAction() : CodeGenAction(Backend_EmitMCNull) {}

EmitObjAction::EmitObjAction() : CodeGenAction(Backend_EmitObj) {}