lib/Target/X86/X86AsmPrinter.cpp

//===-- X86AsmPrinter.cpp - Convert X86 LLVM IR to X86 assembly -----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file the shared super class printer that converts from our internal
// representation of machine-dependent LLVM code to Intel and AT&T format
// assembly language.
// This printer is the output mechanism used by `llc'.
//
//===----------------------------------------------------------------------===//

#include "X86ATTAsmPrinter.h"
#include "X86IntelAsmPrinter.h"
#include "X86.h"
#include "llvm/Module.h"
#include "llvm/Type.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Support/Mangler.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
using namespace x86;

Statistic<> llvm::x86::EmittedInsts("asm-printer",
                                    "Number of machine instrs printed");

enum AsmWriterFlavorTy { att, intel };
cl::opt<AsmWriterFlavorTy>
AsmWriterFlavor("x86-asm-syntax",
                cl::desc("Choose style of code to emit from X86 backend:"),
                cl::values(
                           clEnumVal(att,   "  Emit AT&T-style assembly"),
                           clEnumVal(intel, "  Emit Intel-style assembly"),
                           clEnumValEnd),
                cl::init(att));

/// doInitialization
bool X86SharedAsmPrinter::doInitialization(Module &M) {
  bool forCygwin = false;
  forDarwin = false;
  forELF    = false;
  bool forWin32 = false;
  const std::string& TT = M.getTargetTriple();
  if (TT.length() > 5) {
    forCygwin = TT.find("cygwin") != std::string::npos ||
                TT.find("mingw")  != std::string::npos;
    forDarwin = TT.find("darwin") != std::string::npos;
    if (!forDarwin && !forCygwin)
      forELF = true;
  } else if (TT.empty()) {
#if defined(__CYGWIN__) || defined(__MINGW32__)
    forCygwin = true;
#elif defined(__APPLE__)
    forDarwin = true;
#elif defined(_WIN32)
    forWin32 = true;
#else
    forELF = true;
#endif
  }

  if (forDarwin) {
    AlignmentIsInBytes = false;
    GlobalPrefix = "_";
    Data64bitsDirective = 0;       // we can't emit a 64-bit unit
    ZeroDirective = "\t.space\t";  // ".space N" emits N zeros.
    PrivateGlobalPrefix = "L";     // Marker for constant pool idxs
    ConstantPoolSection = "\t.const\n";
    LCOMMDirective = "\t.lcomm\t";
    COMMDirectiveTakesAlignment = false;
  } else if (forCygwin) {
    GlobalPrefix = "_";
    COMMDirectiveTakesAlignment = false;
  } else if (forWin32) {
    GlobalPrefix = "_";
  }  
  
  return AsmPrinter::doInitialization(M);
}

bool X86SharedAsmPrinter::doFinalization(Module &M) {
  const TargetData &TD = TM.getTargetData();

  // Print out module-level global variables here.
  for (Module::const_global_iterator I = M.global_begin(),
         E = M.global_end(); I != E; ++I)
    if (I->hasInitializer()) {   // External global require no code
      O << "\n\n";
      std::string name = Mang->getValueName(I);
      Constant *C = I->getInitializer();
      unsigned Size = TD.getTypeSize(C->getType());
      unsigned Align = TD.getTypeAlignmentShift(C->getType());

      switch (I->getLinkage()) {
      default: assert(0 && "Unknown linkage type!");
      case GlobalValue::LinkOnceLinkage:
      case GlobalValue::WeakLinkage:   // FIXME: Verify correct for weak.
        if (C->isNullValue()) {
          O << COMMDirective << name << "," << Size;
          if (COMMDirectiveTakesAlignment)
            O << "," << (1 << Align);
          O << "\t\t# ";
          WriteAsOperand(O, I, true, true, &M);
          O << "\n";
          continue;
        }
        
        // Nonnull linkonce -> weak
        O << "\t.weak " << name << "\n";
        O << "\t.section\t.llvm.linkonce.d." << name << ",\"aw\",@progbits\n";
        SwitchSection("", I);
        break;
      case GlobalValue::InternalLinkage:
        if (C->isNullValue()) {
          if (LCOMMDirective) {
            O << LCOMMDirective << name << "," << Size << "," << Align;
            continue;
          } else {
            SwitchSection(".bss", I);
            O << "\t.local " << name << "\n";
            O << COMMDirective << name << "," << Size;
            if (COMMDirectiveTakesAlignment)
              O << "," << (1 << Align);
            O << "\t\t# ";
            WriteAsOperand(O, I, true, true, &M);
            O << "\n";
            continue;
          }
        }
        SwitchSection(C->isNullValue() ? ".bss" : ".data", I);
        break;
      case GlobalValue::AppendingLinkage:
        // FIXME: appending linkage variables should go into a section of
        // their name or something.  For now, just emit them as external.
      case GlobalValue::ExternalLinkage:
        SwitchSection(C->isNullValue() ? ".bss" : ".data", I);
        // If external or appending, declare as a global symbol
        O << "\t.globl " << name << "\n";
        break;
      }

      EmitAlignment(Align);
      if (forELF) {
        O << "\t.type " << name << ",@object\n";
        O << "\t.size " << name << "," << Size << "\n";
      }
      O << name << ":\t\t\t\t# ";
      WriteAsOperand(O, I, true, true, &M);
      O << " = ";
      WriteAsOperand(O, C, false, false, &M);
      O << "\n";
      EmitGlobalConstant(C);
    }

  if (forDarwin) {
    SwitchSection("", 0);
    // Output stubs for external global variables
    if (GVStubs.begin() != GVStubs.end())
      O << "\t.non_lazy_symbol_pointer\n";
    for (std::set<std::string>::iterator i = GVStubs.begin(), e = GVStubs.end();
         i != e; ++i) {
      O << "L" << *i << "$non_lazy_ptr:\n";
      O << "\t.indirect_symbol " << *i << "\n";
      O << "\t.long\t0\n";
    }

    // Output stubs for dynamically-linked functions
    unsigned j = 1;
    for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end();
         i != e; ++i, ++j) {
      O << "\t.symbol_stub\n";
      O << "L" << *i << "$stub:\n";
      O << "\t.indirect_symbol " << *i << "\n";
      O << "\tjmp\t*L" << j << "$lz\n";
      O << "L" << *i << "$stub_binder:\n";
      O << "\tpushl\t$L" << j << "$lz\n";
      O << "\tjmp\tdyld_stub_binding_helper\n";
      O << "\t.section __DATA, __la_sym_ptr3,lazy_symbol_pointers\n";
      O << "L" << j << "$lz:\n";
      O << "\t.indirect_symbol " << *i << "\n";
      O << "\t.long\tL" << *i << "$stub_binder\n";
    }

    O << "\n";

    // Output stubs for link-once variables
    if (LinkOnceStubs.begin() != LinkOnceStubs.end())
      O << ".data\n.align 2\n";
    for (std::set<std::string>::iterator i = LinkOnceStubs.begin(),
         e = LinkOnceStubs.end(); i != e; ++i) {
      O << "L" << *i << "$non_lazy_ptr:\n"
        << "\t.long\t" << *i << '\n';
    }
  }

  AsmPrinter::doFinalization(M);
  return false; // success
}

/// createX86CodePrinterPass - Returns a pass that prints the X86 assembly code
/// for a MachineFunction to the given output stream, using the given target
/// machine description.
///
FunctionPass *llvm::createX86CodePrinterPass(std::ostream &o,TargetMachine &tm){
  switch (AsmWriterFlavor) {
  default:
    assert(0 && "Unknown asm flavor!");
  case intel:
    return new X86IntelAsmPrinter(o, tm);
  case att:
    return new X86ATTAsmPrinter(o, tm);
  }
}