lib/Target/DarwinTargetAsmInfo.cpp

//===-- DarwinTargetAsmInfo.cpp - Darwin asm properties ---------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines target asm properties related what form asm statements
// should take in general on Darwin-based targets
//
//===----------------------------------------------------------------------===//

#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Mangler.h"
#include "llvm/Target/DarwinTargetAsmInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetData.h"

using namespace llvm;

DarwinTargetAsmInfo::DarwinTargetAsmInfo(const TargetMachine &TM) 
  : TargetAsmInfo(TM) {
 
  // Common settings for all Darwin targets.
  // Syntax:
  GlobalPrefix = "_";
  PrivateGlobalPrefix = "L";
  LinkerPrivateGlobalPrefix = "l";  // Marker for some ObjC metadata
  NeedsSet = true;
  NeedsIndirectEncoding = true;
  AllowQuotesInName = true;
  HasSingleParameterDotFile = false;

  // In non-PIC modes, emit a special label before jump tables so that the
  // linker can perform more accurate dead code stripping.  We do not check the
  // relocation model here since it can be overridden later.
  JumpTableSpecialLabelPrefix = "l";
    
  // Directives:
  WeakDefDirective = "\t.weak_definition ";
  WeakRefDirective = "\t.weak_reference ";
  HiddenDirective = "\t.private_extern ";
    
  // Sections:
  CStringSection = "\t.cstring";
  JumpTableDataSection = "\t.const";
  BSSSection = 0;

  if (TM.getRelocationModel() == Reloc::Static) {
    StaticCtorsSection = ".constructor";
    StaticDtorsSection = ".destructor";
  } else {
    StaticCtorsSection = ".mod_init_func";
    StaticDtorsSection = ".mod_term_func";
  }
    
  // _foo.eh symbols are currently always exported so that the linker knows
  // about them.  This may not strictly be necessary on 10.6 and later, but it
  // doesn't hurt anything.
  Is_EHSymbolPrivate = false;
    
  DwarfAbbrevSection = ".section __DWARF,__debug_abbrev,regular,debug";
  DwarfInfoSection = ".section __DWARF,__debug_info,regular,debug";
  DwarfLineSection = ".section __DWARF,__debug_line,regular,debug";
  DwarfFrameSection = ".section __DWARF,__debug_frame,regular,debug";
  DwarfPubNamesSection = ".section __DWARF,__debug_pubnames,regular,debug";
  DwarfPubTypesSection = ".section __DWARF,__debug_pubtypes,regular,debug";
  DwarfStrSection = ".section __DWARF,__debug_str,regular,debug";
  DwarfLocSection = ".section __DWARF,__debug_loc,regular,debug";
  DwarfARangesSection = ".section __DWARF,__debug_aranges,regular,debug";
  DwarfRangesSection = ".section __DWARF,__debug_ranges,regular,debug";
  DwarfMacroInfoSection = ".section __DWARF,__debug_macinfo,regular,debug";
}

/// emitUsedDirectiveFor - On Darwin, internally linked data beginning with
/// the PrivateGlobalPrefix or the LinkerPrivateGlobalPrefix does not have the
/// directive emitted (this occurs in ObjC metadata).
bool DarwinTargetAsmInfo::emitUsedDirectiveFor(const GlobalValue* GV,
                                               Mangler *Mang) const {
  if (!GV) return false;
  
  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
  if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
    // FIXME: ObjC metadata is currently emitted as internal symbols that have
    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
    // this horrible hack can go away.
    const std::string &Name = Mang->getMangledName(GV);
    if (Name[0] == 'L' || Name[0] == 'l')
      return false;
  }

  return true;
}