lib/Target/DarwinTargetAsmInfo.cpp

   1 //===-- DarwinTargetAsmInfo.cpp - Darwin asm properties ---------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines target asm properties related what form asm statements
  11 // should take in general on Darwin-based targets
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/Constants.h"
  16 #include "llvm/DerivedTypes.h"
  17 #include "llvm/Function.h"
  18 #include "llvm/GlobalVariable.h"
  19 #include "llvm/ADT/StringExtras.h"
  20 #include "llvm/Support/ErrorHandling.h"
  21 #include "llvm/Support/Mangler.h"
  22 #include "llvm/Target/DarwinTargetAsmInfo.h"
  23 #include "llvm/Target/TargetMachine.h"
  24 #include "llvm/Target/TargetData.h"
  25
  26 using namespace llvm;
  27
  28 DarwinTargetAsmInfo::DarwinTargetAsmInfo(const TargetMachine &TM)
  29   : TargetAsmInfo(TM) {
  30
  31   CStringSection_ = getUnnamedSection("\t.cstring",
  32                                 SectionFlags::Mergeable | SectionFlags::Strings);
  33   FourByteConstantSection = getUnnamedSection("\t.literal4\n",
  34                                               SectionFlags::Mergeable);
  35   EightByteConstantSection = getUnnamedSection("\t.literal8\n",
  36                                                SectionFlags::Mergeable);
  37
  38   // Note: 16-byte constant section is subtarget specific and should be provided
  39   // there, if needed.
  40   SixteenByteConstantSection = 0;
  41
  42   ReadOnlySection = getUnnamedSection("\t.const\n", SectionFlags::None);
  43
  44   TextCoalSection =
  45     getNamedSection("\t__TEXT,__textcoal_nt,coalesced,pure_instructions",
  46                     SectionFlags::Code);
  47   ConstTextCoalSection = getNamedSection("\t__TEXT,__const_coal,coalesced",
  48                                          SectionFlags::None);
  49   ConstDataCoalSection = getNamedSection("\t__DATA,__const_coal,coalesced",
  50                                          SectionFlags::None);
  51   ConstDataSection = getUnnamedSection(".const_data", SectionFlags::None);
  52   DataCoalSection = getNamedSection("\t__DATA,__datacoal_nt,coalesced",
  53                                     SectionFlags::Writeable);
  54
  55
  56   // Common settings for all Darwin targets.
  57   // Syntax:
  58   GlobalPrefix = "_";
  59   PrivateGlobalPrefix = "L";
  60   LessPrivateGlobalPrefix = "l";  // Marker for some ObjC metadata
  61   NeedsSet = true;
  62   NeedsIndirectEncoding = true;
  63   AllowQuotesInName = true;
  64   HasSingleParameterDotFile = false;
  65
  66   // In non-PIC modes, emit a special label before jump tables so that the
  67   // linker can perform more accurate dead code stripping.  We do not check the
  68   // relocation model here since it can be overridden later.
  69   JumpTableSpecialLabelPrefix = "l";
  70
  71   // Directives:
  72   WeakDefDirective = "\t.weak_definition ";
  73   WeakRefDirective = "\t.weak_reference ";
  74   HiddenDirective = "\t.private_extern ";
  75
  76   // Sections:
  77   CStringSection = "\t.cstring";
  78   JumpTableDataSection = "\t.const\n";
  79   BSSSection = 0;
  80
  81   if (TM.getRelocationModel() == Reloc::Static) {
  82     StaticCtorsSection = ".constructor";
  83     StaticDtorsSection = ".destructor";
  84   } else {
  85     StaticCtorsSection = ".mod_init_func";
  86     StaticDtorsSection = ".mod_term_func";
  87   }
  88
  89   DwarfAbbrevSection = ".section __DWARF,__debug_abbrev,regular,debug";
  90   DwarfInfoSection = ".section __DWARF,__debug_info,regular,debug";
  91   DwarfLineSection = ".section __DWARF,__debug_line,regular,debug";
  92   DwarfFrameSection = ".section __DWARF,__debug_frame,regular,debug";
  93   DwarfPubNamesSection = ".section __DWARF,__debug_pubnames,regular,debug";
  94   DwarfPubTypesSection = ".section __DWARF,__debug_pubtypes,regular,debug";
  95   DwarfStrSection = ".section __DWARF,__debug_str,regular,debug";
  96   DwarfLocSection = ".section __DWARF,__debug_loc,regular,debug";
  97   DwarfARangesSection = ".section __DWARF,__debug_aranges,regular,debug";
  98   DwarfRangesSection = ".section __DWARF,__debug_ranges,regular,debug";
  99   DwarfMacroInfoSection = ".section __DWARF,__debug_macinfo,regular,debug";
 100 }
 101
 102 /// emitUsedDirectiveFor - On Darwin, internally linked data beginning with
 103 /// the PrivateGlobalPrefix or the LessPrivateGlobalPrefix does not have the
 104 /// directive emitted (this occurs in ObjC metadata).
 105 bool
 106 DarwinTargetAsmInfo::emitUsedDirectiveFor(const GlobalValue* GV,
 107                                           Mangler *Mang) const {
 108   if (GV==0)
 109     return false;
 110
 111   /// FIXME: WHAT IS THIS?
 112
 113   if (GV->hasLocalLinkage() && !isa<Function>(GV) &&
 114       ((strlen(getPrivateGlobalPrefix()) != 0 &&
 115         Mang->getMangledName(GV).substr(0,strlen(getPrivateGlobalPrefix())) ==
 116           getPrivateGlobalPrefix()) ||
 117        (strlen(getLessPrivateGlobalPrefix()) != 0 &&
 118         Mang->getMangledName(GV).substr(0,
 119                                         strlen(getLessPrivateGlobalPrefix())) ==
 120           getLessPrivateGlobalPrefix())))
 121     return false;
 122   return true;
 123 }
 124
 125 const Section*
 126 DarwinTargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
 127   SectionKind::Kind Kind = SectionKindForGlobal(GV);
 128   bool isWeak = GV->isWeakForLinker();
 129   bool isNonStatic = TM.getRelocationModel() != Reloc::Static;
 130
 131   switch (Kind) {
 132    case SectionKind::Text:
 133     if (isWeak)
 134       return TextCoalSection;
 135     else
 136       return TextSection;
 137    case SectionKind::Data:
 138    case SectionKind::ThreadData:
 139    case SectionKind::BSS:
 140    case SectionKind::ThreadBSS:
 141     if (cast<GlobalVariable>(GV)->isConstant())
 142       return (isWeak ? ConstDataCoalSection : ConstDataSection);
 143     else
 144       return (isWeak ? DataCoalSection : DataSection);
 145    case SectionKind::ROData:
 146     return (isWeak ? ConstDataCoalSection :
 147             (isNonStatic ? ConstDataSection : getReadOnlySection()));
 148    case SectionKind::RODataMergeStr:
 149     return (isWeak ?
 150             ConstTextCoalSection :
 151             MergeableStringSection(cast<GlobalVariable>(GV)));
 152    case SectionKind::RODataMergeConst:
 153     return (isWeak ?
 154             ConstDataCoalSection:
 155             MergeableConstSection(cast<GlobalVariable>(GV)));
 156    default:
 157     llvm_unreachable("Unsuported section kind for global");
 158   }
 159
 160   // FIXME: Do we have any extra special weird cases?
 161   return NULL;
 162 }
 163
 164 const Section*
 165 DarwinTargetAsmInfo::MergeableStringSection(const GlobalVariable *GV) const {
 166   const TargetData *TD = TM.getTargetData();
 167   Constant *C = cast<GlobalVariable>(GV)->getInitializer();
 168   const Type *Ty = cast<ArrayType>(C->getType())->getElementType();
 169
 170   unsigned Size = TD->getTypeAllocSize(Ty);
 171   if (Size) {
 172     unsigned Align = TD->getPreferredAlignment(GV);
 173     if (Align <= 32)
 174       return getCStringSection_();
 175   }
 176
 177   return getReadOnlySection();
 178 }
 179
 180 const Section*
 181 DarwinTargetAsmInfo::MergeableConstSection(const GlobalVariable *GV) const {
 182   Constant *C = GV->getInitializer();
 183
 184   return MergeableConstSection(C->getType());
 185 }
 186
 187 inline const Section*
 188 DarwinTargetAsmInfo::MergeableConstSection(const Type *Ty) const {
 189   const TargetData *TD = TM.getTargetData();
 190
 191   unsigned Size = TD->getTypeAllocSize(Ty);
 192   if (Size == 4)
 193     return FourByteConstantSection;
 194   else if (Size == 8)
 195     return EightByteConstantSection;
 196   else if (Size == 16 && SixteenByteConstantSection)
 197     return SixteenByteConstantSection;
 198
 199   return getReadOnlySection();
 200 }
 201
 202 const Section*
 203 DarwinTargetAsmInfo::SelectSectionForMachineConst(const Type *Ty) const {
 204   const Section* S = MergeableConstSection(Ty);
 205
 206   // Handle weird special case, when compiling PIC stuff.
 207   if (S == getReadOnlySection() &&
 208       TM.getRelocationModel() != Reloc::Static)
 209     return ConstDataSection;
 210
 211   return S;
 212 }
 213
 214 std::string
 215 DarwinTargetAsmInfo::UniqueSectionForGlobal(const GlobalValue* GV,
 216                                                SectionKind::Kind kind) const {
 217   llvm_unreachable("Darwin does not use unique sections");
 218   return "";
 219 }