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      1 //===-- X86MCAsmInfo.cpp - X86 asm properties -----------------------------===//
      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 X86MCAsmInfo properties.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "X86MCAsmInfo.h"
     15 #include "llvm/ADT/Triple.h"
     16 #include "llvm/MC/MCContext.h"
     17 #include "llvm/MC/MCExpr.h"
     18 #include "llvm/MC/MCSectionELF.h"
     19 #include "llvm/MC/MCStreamer.h"
     20 #include "llvm/Support/CommandLine.h"
     21 #include "llvm/Support/ELF.h"
     22 using namespace llvm;
     23 
     24 enum AsmWriterFlavorTy {
     25   // Note: This numbering has to match the GCC assembler dialects for inline
     26   // asm alternatives to work right.
     27   ATT = 0, Intel = 1
     28 };
     29 
     30 static cl::opt<AsmWriterFlavorTy>
     31 AsmWriterFlavor("x86-asm-syntax", cl::init(ATT),
     32   cl::desc("Choose style of code to emit from X86 backend:"),
     33   cl::values(clEnumValN(ATT,   "att",   "Emit AT&T-style assembly"),
     34              clEnumValN(Intel, "intel", "Emit Intel-style assembly"),
     35              clEnumValEnd));
     36 
     37 
     38 static const char *const x86_asm_table[] = {
     39   "{si}", "S",
     40   "{di}", "D",
     41   "{ax}", "a",
     42   "{cx}", "c",
     43   "{memory}", "memory",
     44   "{flags}", "",
     45   "{dirflag}", "",
     46   "{fpsr}", "",
     47   "{fpcr}", "",
     48   "{cc}", "cc",
     49   0,0};
     50 
     51 X86MCAsmInfoDarwin::X86MCAsmInfoDarwin(const Triple &T) {
     52   bool is64Bit = T.getArch() == Triple::x86_64;
     53   if (is64Bit)
     54     PointerSize = 8;
     55 
     56   AsmTransCBE = x86_asm_table;
     57   AssemblerDialect = AsmWriterFlavor;
     58 
     59   TextAlignFillValue = 0x90;
     60 
     61   if (!is64Bit)
     62     Data64bitsDirective = 0;       // we can't emit a 64-bit unit
     63 
     64   // Use ## as a comment string so that .s files generated by llvm can go
     65   // through the GCC preprocessor without causing an error.  This is needed
     66   // because "clang foo.s" runs the C preprocessor, which is usually reserved
     67   // for .S files on other systems.  Perhaps this is because the file system
     68   // wasn't always case preserving or something.
     69   CommentString = "##";
     70   PCSymbol = ".";
     71 
     72   SupportsDebugInformation = true;
     73   DwarfUsesInlineInfoSection = true;
     74 
     75   // Exceptions handling
     76   ExceptionsType = ExceptionHandling::DwarfCFI;
     77 }
     78 
     79 X86_64MCAsmInfoDarwin::X86_64MCAsmInfoDarwin(const Triple &Triple)
     80   : X86MCAsmInfoDarwin(Triple) {
     81 }
     82 
     83 X86ELFMCAsmInfo::X86ELFMCAsmInfo(const Triple &T) {
     84   if (T.getArch() == Triple::x86_64)
     85     PointerSize = 8;
     86 
     87   AsmTransCBE = x86_asm_table;
     88   AssemblerDialect = AsmWriterFlavor;
     89 
     90   TextAlignFillValue = 0x90;
     91 
     92   PrivateGlobalPrefix = ".L";
     93   WeakRefDirective = "\t.weak\t";
     94   PCSymbol = ".";
     95 
     96   // Set up DWARF directives
     97   HasLEB128 = true;  // Target asm supports leb128 directives (little-endian)
     98 
     99   // Debug Information
    100   SupportsDebugInformation = true;
    101 
    102   // Exceptions handling
    103   ExceptionsType = ExceptionHandling::DwarfCFI;
    104 
    105   // OpenBSD has buggy support for .quad in 32-bit mode, just split into two
    106   // .words.
    107   if (T.getOS() == Triple::OpenBSD && T.getArch() == Triple::x86)
    108     Data64bitsDirective = 0;
    109 }
    110 
    111 const MCExpr *
    112 X86_64MCAsmInfoDarwin::getExprForPersonalitySymbol(const MCSymbol *Sym,
    113                                                    unsigned Encoding,
    114                                                    MCStreamer &Streamer) const {
    115   MCContext &Context = Streamer.getContext();
    116   const MCExpr *Res =
    117     MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_GOTPCREL, Context);
    118   const MCExpr *Four = MCConstantExpr::Create(4, Context);
    119   return MCBinaryExpr::CreateAdd(Res, Four, Context);
    120 }
    121 
    122 const MCSection *X86ELFMCAsmInfo::
    123 getNonexecutableStackSection(MCContext &Ctx) const {
    124   return Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS,
    125                            0, SectionKind::getMetadata());
    126 }
    127 
    128 X86MCAsmInfoCOFF::X86MCAsmInfoCOFF(const Triple &Triple) {
    129   if (Triple.getArch() == Triple::x86_64) {
    130     GlobalPrefix = "";
    131     PrivateGlobalPrefix = ".L";
    132   }
    133 
    134   AsmTransCBE = x86_asm_table;
    135   AssemblerDialect = AsmWriterFlavor;
    136 
    137   TextAlignFillValue = 0x90;
    138 }
    139