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/Mangler.h"
  21 #include "llvm/Target/DarwinTargetAsmInfo.h"
  22 #include "llvm/Target/TargetMachine.h"
  23 #include "llvm/Target/TargetData.h"
  24
  25 using namespace llvm;
  26
  27 DarwinTargetAsmInfo::DarwinTargetAsmInfo(const TargetMachine &TM)
  28   : TargetAsmInfo(TM) {
  29
  30   CStringSection_ = getUnnamedSection("\t.cstring",
  31                                 SectionFlags::Mergeable | SectionFlags::Strings);
  32   FourByteConstantSection = getUnnamedSection("\t.literal4\n",
  33                                               SectionFlags::Mergeable);
  34   EightByteConstantSection = getUnnamedSection("\t.literal8\n",
  35                                                SectionFlags::Mergeable);
  36
  37   // Note: 16-byte constant section is subtarget specific and should be provided
  38   // there, if needed.
  39   SixteenByteConstantSection = 0;
  40
  41   ReadOnlySection = getUnnamedSection("\t.const\n", SectionFlags::None);
  42
  43   TextCoalSection =
  44     getNamedSection("\t__TEXT,__textcoal_nt,coalesced,pure_instructions",
  45                     SectionFlags::Code);
  46   ConstTextCoalSection = getNamedSection("\t__TEXT,__const_coal,coalesced",
  47                                          SectionFlags::None);
  48   ConstDataCoalSection = getNamedSection("\t__DATA,__const_coal,coalesced",
  49                                          SectionFlags::None);
  50   ConstDataSection = getUnnamedSection(".const_data", SectionFlags::None);
  51   DataCoalSection = getNamedSection("\t__DATA,__datacoal_nt,coalesced",
  52                                     SectionFlags::Writeable);
  53 }
  54
  55 /// emitUsedDirectiveFor - On Darwin, internally linked data beginning with
  56 /// the PrivateGlobalPrefix or the LessPrivateGlobalPrefix does not have the
  57 /// directive emitted (this occurs in ObjC metadata).
  58
  59 bool
  60 DarwinTargetAsmInfo::emitUsedDirectiveFor(const GlobalValue* GV,
  61                                           Mangler *Mang) const {
  62   if (GV==0)
  63     return false;
  64   if (GV->hasLocalLinkage() && !isa<Function>(GV) &&
  65       ((strlen(getPrivateGlobalPrefix()) != 0 &&
  66         Mang->getValueName(GV).substr(0,strlen(getPrivateGlobalPrefix())) ==
  67           getPrivateGlobalPrefix()) ||
  68        (strlen(getLessPrivateGlobalPrefix()) != 0 &&
  69         Mang->getValueName(GV).substr(0,strlen(getLessPrivateGlobalPrefix())) ==
  70           getLessPrivateGlobalPrefix())))
  71     return false;
  72   return true;
  73 }
  74
  75 const Section*
  76 DarwinTargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
  77   SectionKind::Kind Kind = SectionKindForGlobal(GV);
  78   bool isWeak = GV->isWeakForLinker();
  79   bool isNonStatic = TM.getRelocationModel() != Reloc::Static;
  80
  81   switch (Kind) {
  82    case SectionKind::Text:
  83     if (isWeak)
  84       return TextCoalSection;
  85     else
  86       return TextSection;
  87    case SectionKind::Data:
  88    case SectionKind::ThreadData:
  89    case SectionKind::BSS:
  90    case SectionKind::ThreadBSS:
  91     if (cast<GlobalVariable>(GV)->isConstant())
  92       return (isWeak ? ConstDataCoalSection : ConstDataSection);
  93     else
  94       return (isWeak ? DataCoalSection : DataSection);
  95    case SectionKind::ROData:
  96     return (isWeak ? ConstDataCoalSection :
  97             (isNonStatic ? ConstDataSection : getReadOnlySection()));
  98    case SectionKind::RODataMergeStr:
  99     return (isWeak ?
 100             ConstTextCoalSection :
 101             MergeableStringSection(cast<GlobalVariable>(GV)));
 102    case SectionKind::RODataMergeConst:
 103     return (isWeak ?
 104             ConstDataCoalSection:
 105             MergeableConstSection(cast<GlobalVariable>(GV)));
 106    default:
 107     assert(0 && "Unsuported section kind for global");
 108   }
 109
 110   // FIXME: Do we have any extra special weird cases?
 111   return NULL;
 112 }
 113
 114 const Section*
 115 DarwinTargetAsmInfo::MergeableStringSection(const GlobalVariable *GV) const {
 116   const TargetData *TD = TM.getTargetData();
 117   Constant *C = cast<GlobalVariable>(GV)->getInitializer();
 118   const Type *Ty = cast<ArrayType>(C->getType())->getElementType();
 119
 120   unsigned Size = TD->getTypePaddedSize(Ty);
 121   if (Size) {
 122     unsigned Align = TD->getPreferredAlignment(GV);
 123     if (Align <= 32)
 124       return getCStringSection_();
 125   }
 126
 127   return getReadOnlySection();
 128 }
 129
 130 const Section*
 131 DarwinTargetAsmInfo::MergeableConstSection(const GlobalVariable *GV) const {
 132   Constant *C = GV->getInitializer();
 133
 134   return MergeableConstSection(C->getType());
 135 }
 136
 137 inline const Section*
 138 DarwinTargetAsmInfo::MergeableConstSection(const Type *Ty) const {
 139   const TargetData *TD = TM.getTargetData();
 140
 141   unsigned Size = TD->getTypePaddedSize(Ty);
 142   if (Size == 4)
 143     return FourByteConstantSection;
 144   else if (Size == 8)
 145     return EightByteConstantSection;
 146   else if (Size == 16 && SixteenByteConstantSection)
 147     return SixteenByteConstantSection;
 148
 149   return getReadOnlySection();
 150 }
 151
 152 const Section*
 153 DarwinTargetAsmInfo::SelectSectionForMachineConst(const Type *Ty) const {
 154   const Section* S = MergeableConstSection(Ty);
 155
 156   // Handle weird special case, when compiling PIC stuff.
 157   if (S == getReadOnlySection() &&
 158       TM.getRelocationModel() != Reloc::Static)
 159     return ConstDataSection;
 160
 161   return S;
 162 }
 163
 164 std::string
 165 DarwinTargetAsmInfo::UniqueSectionForGlobal(const GlobalValue* GV,
 166                                                SectionKind::Kind kind) const {
 167   assert(0 && "Darwin does not use unique sections");
 168   return "";
 169 }