lib/Target/X86/X86TargetAsmInfo.cpp

   1 //===-- X86TargetAsmInfo.cpp - X86 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 contains the declarations of the X86TargetAsmInfo properties.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "X86TargetAsmInfo.h"
  15 #include "X86TargetMachine.h"
  16 #include "X86Subtarget.h"
  17 #include "llvm/DerivedTypes.h"
  18 #include "llvm/InlineAsm.h"
  19 #include "llvm/Instructions.h"
  20 #include "llvm/Intrinsics.h"
  21 #include "llvm/Module.h"
  22 #include "llvm/ADT/StringExtras.h"
  23 #include "llvm/Support/Dwarf.h"
  24
  25 using namespace llvm;
  26 using namespace llvm::dwarf;
  27
  28 static const char *const x86_asm_table[] = {
  29                                       "{si}", "S",
  30                                       "{di}", "D",
  31                                       "{ax}", "a",
  32                                       "{cx}", "c",
  33                                       "{memory}", "memory",
  34                                       "{flags}", "",
  35                                       "{dirflag}", "",
  36                                       "{fpsr}", "",
  37                                       "{cc}", "cc",
  38                                       0,0};
  39
  40 X86TargetAsmInfo::X86TargetAsmInfo(const X86TargetMachine &TM) {
  41   const X86Subtarget *Subtarget = &TM.getSubtarget<X86Subtarget>();
  42   X86TM = &TM;
  43
  44   // FIXME - Should be simplified.
  45
  46   AsmTransCBE = x86_asm_table;
  47
  48   switch (Subtarget->TargetType) {
  49   case X86Subtarget::isDarwin:
  50     AlignmentIsInBytes = false;
  51     TextAlignFillValue = 0x90;
  52     GlobalPrefix = "_";
  53     if (!Subtarget->is64Bit())
  54       Data64bitsDirective = 0;       // we can't emit a 64-bit unit
  55     ZeroDirective = "\t.space\t";  // ".space N" emits N zeros.
  56     PrivateGlobalPrefix = "L";     // Marker for constant pool idxs
  57     BSSSection = 0;                       // no BSS section.
  58     ZeroFillDirective = "\t.zerofill\t";  // Uses .zerofill
  59     ConstantPoolSection = "\t.const\n";
  60     JumpTableDataSection = "\t.const\n";
  61     CStringSection = "\t.cstring";
  62     FourByteConstantSection = "\t.literal4\n";
  63     EightByteConstantSection = "\t.literal8\n";
  64     if (Subtarget->is64Bit())
  65       SixteenByteConstantSection = "\t.literal16\n";
  66     ReadOnlySection = "\t.const\n";
  67     LCOMMDirective = "\t.lcomm\t";
  68     SwitchToSectionDirective = "\t.section ";
  69     COMMDirectiveTakesAlignment = false;
  70     HasDotTypeDotSizeDirective = false;
  71     if (TM.getRelocationModel() == Reloc::Static) {
  72       StaticCtorsSection = ".constructor";
  73       StaticDtorsSection = ".destructor";
  74     } else {
  75       StaticCtorsSection = ".mod_init_func";
  76       StaticDtorsSection = ".mod_term_func";
  77     }
  78     if (Subtarget->is64Bit()) {
  79       PersonalityPrefix = "";
  80       PersonalitySuffix = "+4@GOTPCREL";
  81     } else {
  82       PersonalityPrefix = "L";
  83       PersonalitySuffix = "$non_lazy_ptr";
  84     }
  85     NeedsIndirectEncoding = true;
  86     InlineAsmStart = "## InlineAsm Start";
  87     InlineAsmEnd = "## InlineAsm End";
  88     CommentString = "##";
  89     SetDirective = "\t.set";
  90     PCSymbol = ".";
  91     UsedDirective = "\t.no_dead_strip\t";
  92     WeakDefDirective = "\t.weak_definition ";
  93     WeakRefDirective = "\t.weak_reference ";
  94     HiddenDirective = "\t.private_extern ";
  95     ProtectedDirective = "\t.globl\t";
  96
  97     // In non-PIC modes, emit a special label before jump tables so that the
  98     // linker can perform more accurate dead code stripping.
  99     if (TM.getRelocationModel() != Reloc::PIC_) {
 100       // Emit a local label that is preserved until the linker runs.
 101       JumpTableSpecialLabelPrefix = "l";
 102     }
 103
 104     SupportsDebugInformation = true;
 105     NeedsSet = true;
 106     DwarfAbbrevSection = ".section __DWARF,__debug_abbrev,regular,debug";
 107     DwarfInfoSection = ".section __DWARF,__debug_info,regular,debug";
 108     DwarfLineSection = ".section __DWARF,__debug_line,regular,debug";
 109     DwarfFrameSection = ".section __DWARF,__debug_frame,regular,debug";
 110     DwarfPubNamesSection = ".section __DWARF,__debug_pubnames,regular,debug";
 111     DwarfPubTypesSection = ".section __DWARF,__debug_pubtypes,regular,debug";
 112     DwarfStrSection = ".section __DWARF,__debug_str,regular,debug";
 113     DwarfLocSection = ".section __DWARF,__debug_loc,regular,debug";
 114     DwarfARangesSection = ".section __DWARF,__debug_aranges,regular,debug";
 115     DwarfRangesSection = ".section __DWARF,__debug_ranges,regular,debug";
 116     DwarfMacInfoSection = ".section __DWARF,__debug_macinfo,regular,debug";
 117
 118     // Exceptions handling
 119     SupportsExceptionHandling = true;
 120     GlobalEHDirective = "\t.globl\t";
 121     SupportsWeakOmittedEHFrame = false;
 122     AbsoluteEHSectionOffsets = false;
 123     DwarfEHFrameSection =
 124     ".section __TEXT,__eh_frame,coalesced,no_toc+strip_static_syms+live_support";
 125     DwarfExceptionSection = ".section __DATA,__gcc_except_tab";
 126     break;
 127
 128   case X86Subtarget::isELF:
 129     ReadOnlySection = "\t.section\t.rodata";
 130     FourByteConstantSection = "\t.section\t.rodata.cst4,\"aM\",@progbits,4";
 131     EightByteConstantSection = "\t.section\t.rodata.cst8,\"aM\",@progbits,8";
 132     SixteenByteConstantSection = "\t.section\t.rodata.cst16,\"aM\",@progbits,16";
 133     CStringSection = "\t.section\t.rodata.str1.1,\"aMS\",@progbits,1";
 134     PrivateGlobalPrefix = ".L";
 135     WeakRefDirective = "\t.weak\t";
 136     SetDirective = "\t.set\t";
 137     PCSymbol = ".";
 138
 139     // Set up DWARF directives
 140     HasLEB128 = true;  // Target asm supports leb128 directives (little-endian)
 141
 142     // Debug Information
 143     AbsoluteDebugSectionOffsets = true;
 144     SupportsDebugInformation = true;
 145     DwarfAbbrevSection =  "\t.section\t.debug_abbrev,\"\",@progbits";
 146     DwarfInfoSection =    "\t.section\t.debug_info,\"\",@progbits";
 147     DwarfLineSection =    "\t.section\t.debug_line,\"\",@progbits";
 148     DwarfFrameSection =   "\t.section\t.debug_frame,\"\",@progbits";
 149     DwarfPubNamesSection ="\t.section\t.debug_pubnames,\"\",@progbits";
 150     DwarfPubTypesSection ="\t.section\t.debug_pubtypes,\"\",@progbits";
 151     DwarfStrSection =     "\t.section\t.debug_str,\"\",@progbits";
 152     DwarfLocSection =     "\t.section\t.debug_loc,\"\",@progbits";
 153     DwarfARangesSection = "\t.section\t.debug_aranges,\"\",@progbits";
 154     DwarfRangesSection =  "\t.section\t.debug_ranges,\"\",@progbits";
 155     DwarfMacInfoSection = "\t.section\t.debug_macinfo,\"\",@progbits";
 156
 157     // Exceptions handling
 158     if (!Subtarget->is64Bit())
 159       SupportsExceptionHandling = true;
 160     AbsoluteEHSectionOffsets = false;
 161     DwarfEHFrameSection = "\t.section\t.eh_frame,\"aw\",@progbits";
 162     DwarfExceptionSection = "\t.section\t.gcc_except_table,\"a\",@progbits";
 163     break;
 164
 165   case X86Subtarget::isCygwin:
 166   case X86Subtarget::isMingw:
 167     GlobalPrefix = "_";
 168     LCOMMDirective = "\t.lcomm\t";
 169     COMMDirectiveTakesAlignment = false;
 170     HasDotTypeDotSizeDirective = false;
 171     StaticCtorsSection = "\t.section .ctors,\"aw\"";
 172     StaticDtorsSection = "\t.section .dtors,\"aw\"";
 173     HiddenDirective = NULL;
 174     PrivateGlobalPrefix = "L";  // Prefix for private global symbols
 175     WeakRefDirective = "\t.weak\t";
 176     SetDirective = "\t.set\t";
 177
 178     // Set up DWARF directives
 179     HasLEB128 = true;  // Target asm supports leb128 directives (little-endian)
 180     AbsoluteDebugSectionOffsets = true;
 181     AbsoluteEHSectionOffsets = false;
 182     SupportsDebugInformation = true;
 183     DwarfSectionOffsetDirective = "\t.secrel32\t";
 184     DwarfAbbrevSection =  "\t.section\t.debug_abbrev,\"dr\"";
 185     DwarfInfoSection =    "\t.section\t.debug_info,\"dr\"";
 186     DwarfLineSection =    "\t.section\t.debug_line,\"dr\"";
 187     DwarfFrameSection =   "\t.section\t.debug_frame,\"dr\"";
 188     DwarfPubNamesSection ="\t.section\t.debug_pubnames,\"dr\"";
 189     DwarfPubTypesSection ="\t.section\t.debug_pubtypes,\"dr\"";
 190     DwarfStrSection =     "\t.section\t.debug_str,\"dr\"";
 191     DwarfLocSection =     "\t.section\t.debug_loc,\"dr\"";
 192     DwarfARangesSection = "\t.section\t.debug_aranges,\"dr\"";
 193     DwarfRangesSection =  "\t.section\t.debug_ranges,\"dr\"";
 194     DwarfMacInfoSection = "\t.section\t.debug_macinfo,\"dr\"";
 195     break;
 196
 197   case X86Subtarget::isWindows:
 198     GlobalPrefix = "_";
 199     HasDotTypeDotSizeDirective = false;
 200     break;
 201
 202   default: break;
 203   }
 204
 205   if (Subtarget->isFlavorIntel()) {
 206     GlobalPrefix = "_";
 207     CommentString = ";";
 208
 209     PrivateGlobalPrefix = "$";
 210     AlignDirective = "\talign\t";
 211     ZeroDirective = "\tdb\t";
 212     ZeroDirectiveSuffix = " dup(0)";
 213     AsciiDirective = "\tdb\t";
 214     AscizDirective = 0;
 215     Data8bitsDirective = "\tdb\t";
 216     Data16bitsDirective = "\tdw\t";
 217     Data32bitsDirective = "\tdd\t";
 218     Data64bitsDirective = "\tdq\t";
 219     HasDotTypeDotSizeDirective = false;
 220
 221     TextSection = "_text";
 222     DataSection = "_data";
 223     JumpTableDataSection = NULL;
 224     SwitchToSectionDirective = "";
 225     TextSectionStartSuffix = "\tsegment 'CODE'";
 226     DataSectionStartSuffix = "\tsegment 'DATA'";
 227     SectionEndDirectiveSuffix = "\tends\n";
 228   }
 229
 230   // On Linux we must declare when we can use a non-executable stack.
 231   if (Subtarget->isLinux())
 232     NonexecutableStackDirective = "\t.section\t.note.GNU-stack,\"\",@progbits";
 233
 234   AssemblerDialect = Subtarget->getAsmFlavor();
 235 }
 236
 237 bool X86TargetAsmInfo::LowerToBSwap(CallInst *CI) const {
 238   // FIXME: this should verify that we are targetting a 486 or better.  If not,
 239   // we will turn this bswap into something that will be lowered to logical ops
 240   // instead of emitting the bswap asm.  For now, we don't support 486 or lower
 241   // so don't worry about this.
 242
 243   // Verify this is a simple bswap.
 244   if (CI->getNumOperands() != 2 ||
 245       CI->getType() != CI->getOperand(1)->getType() ||
 246       !CI->getType()->isInteger())
 247     return false;
 248
 249   const IntegerType *Ty = dyn_cast<IntegerType>(CI->getType());
 250   if (!Ty || Ty->getBitWidth() % 16 != 0)
 251     return false;
 252
 253   // Okay, we can do this xform, do so now.
 254   const Type *Tys[] = { Ty };
 255   Module *M = CI->getParent()->getParent()->getParent();
 256   Constant *Int = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
 257
 258   Value *Op = CI->getOperand(1);
 259   Op = CallInst::Create(Int, Op, CI->getName(), CI);
 260
 261   CI->replaceAllUsesWith(Op);
 262   CI->eraseFromParent();
 263   return true;
 264 }
 265
 266
 267 bool X86TargetAsmInfo::ExpandInlineAsm(CallInst *CI) const {
 268   InlineAsm *IA = cast<InlineAsm>(CI->getCalledValue());
 269   std::vector<InlineAsm::ConstraintInfo> Constraints = IA->ParseConstraints();
 270
 271   std::string AsmStr = IA->getAsmString();
 272
 273   // TODO: should remove alternatives from the asmstring: "foo {a|b}" -> "foo a"
 274   std::vector<std::string> AsmPieces;
 275   SplitString(AsmStr, AsmPieces, "\n");  // ; as separator?
 276
 277   switch (AsmPieces.size()) {
 278   default: return false;
 279   case 1:
 280     AsmStr = AsmPieces[0];
 281     AsmPieces.clear();
 282     SplitString(AsmStr, AsmPieces, " \t");  // Split with whitespace.
 283
 284     // bswap $0
 285     if (AsmPieces.size() == 2 &&
 286         AsmPieces[0] == "bswap" && AsmPieces[1] == "$0") {
 287       // No need to check constraints, nothing other than the equivalent of
 288       // "=r,0" would be valid here.
 289       return LowerToBSwap(CI);
 290     }
 291     break;
 292   case 3:
 293     if (CI->getType() == Type::Int64Ty && Constraints.size() >= 2 &&
 294         Constraints[0].Codes.size() == 1 && Constraints[0].Codes[0] == "A" &&
 295         Constraints[1].Codes.size() == 1 && Constraints[1].Codes[0] == "0") {
 296       // bswap %eax / bswap %edx / xchgl %eax, %edx  -> llvm.bswap.i64
 297       std::vector<std::string> Words;
 298       SplitString(AsmPieces[0], Words, " \t");
 299       if (Words.size() == 2 && Words[0] == "bswap" && Words[1] == "%eax") {
 300         Words.clear();
 301         SplitString(AsmPieces[1], Words, " \t");
 302         if (Words.size() == 2 && Words[0] == "bswap" && Words[1] == "%edx") {
 303           Words.clear();
 304           SplitString(AsmPieces[2], Words, " \t,");
 305           if (Words.size() == 3 && Words[0] == "xchgl" && Words[1] == "%eax" &&
 306               Words[2] == "%edx") {
 307             return LowerToBSwap(CI);
 308           }
 309         }
 310       }
 311     }
 312     break;
 313   }
 314   return false;
 315 }
 316
 317 /// PreferredEHDataFormat - This hook allows the target to select data
 318 /// format used for encoding pointers in exception handling data. Reason is
 319 /// 0 for data, 1 for code labels, 2 for function pointers. Global is true
 320 /// if the symbol can be relocated.
 321 unsigned X86TargetAsmInfo::PreferredEHDataFormat(DwarfEncoding::Target Reason,
 322                                                  bool Global) const {
 323   const X86Subtarget *Subtarget = &X86TM->getSubtarget<X86Subtarget>();
 324
 325   switch (Subtarget->TargetType) {
 326   case X86Subtarget::isDarwin:
 327    if (Reason == DwarfEncoding::Functions && Global)
 328      return (DW_EH_PE_pcrel | DW_EH_PE_indirect | DW_EH_PE_sdata4);
 329    else if (Reason == DwarfEncoding::CodeLabels || !Global)
 330      return DW_EH_PE_pcrel;
 331    else
 332      return DW_EH_PE_absptr;
 333
 334   case X86Subtarget::isELF:
 335   case X86Subtarget::isCygwin:
 336   case X86Subtarget::isMingw: {
 337     CodeModel::Model CM = X86TM->getCodeModel();
 338
 339     if (X86TM->getRelocationModel() == Reloc::PIC_) {
 340       unsigned Format = 0;
 341
 342       if (!Subtarget->is64Bit())
 343         // 32 bit targets always encode pointers as 4 bytes
 344         Format = DW_EH_PE_sdata4;
 345       else {
 346         // 64 bit targets encode pointers in 4 bytes iff:
 347         // - code model is small OR
 348         // - code model is medium and we're emitting externally visible symbols or
 349         //   any code symbols
 350         if (CM == CodeModel::Small ||
 351             (CM == CodeModel::Medium && (Global ||
 352                                          Reason != DwarfEncoding::Data)))
 353           Format = DW_EH_PE_sdata4;
 354         else
 355           Format = DW_EH_PE_sdata8;
 356       }
 357
 358       if (Global)
 359         Format |= DW_EH_PE_indirect;
 360
 361       return (Format | DW_EH_PE_pcrel);
 362     } else {
 363       if (Subtarget->is64Bit() &&
 364           (CM == CodeModel::Small ||
 365            (CM == CodeModel::Medium && Reason != DwarfEncoding::Data)))
 366         return DW_EH_PE_udata4;
 367       else
 368         return DW_EH_PE_absptr;
 369     }
 370   }
 371
 372   default:
 373    return TargetAsmInfo::PreferredEHDataFormat(Reason, Global);
 374   }
 375 }
 376