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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 void X86MCAsmInfoDarwin::anchor() { }
     39 
     40 X86MCAsmInfoDarwin::X86MCAsmInfoDarwin(const Triple &T) {
     41   bool is64Bit = T.getArch() == Triple::x86_64;
     42   if (is64Bit)
     43     PointerSize = 8;
     44 
     45   AssemblerDialect = AsmWriterFlavor;
     46 
     47   TextAlignFillValue = 0x90;
     48 
     49   if (!is64Bit)
     50     Data64bitsDirective = 0;       // we can't emit a 64-bit unit
     51 
     52   // Use ## as a comment string so that .s files generated by llvm can go
     53   // through the GCC preprocessor without causing an error.  This is needed
     54   // because "clang foo.s" runs the C preprocessor, which is usually reserved
     55   // for .S files on other systems.  Perhaps this is because the file system
     56   // wasn't always case preserving or something.
     57   CommentString = "##";
     58   PCSymbol = ".";
     59 
     60   SupportsDebugInformation = true;
     61   DwarfUsesInlineInfoSection = true;
     62 
     63   // Exceptions handling
     64   ExceptionsType = ExceptionHandling::DwarfCFI;
     65 }
     66 
     67 X86_64MCAsmInfoDarwin::X86_64MCAsmInfoDarwin(const Triple &Triple)
     68   : X86MCAsmInfoDarwin(Triple) {
     69 }
     70 
     71 void X86ELFMCAsmInfo::anchor() { }
     72 
     73 X86ELFMCAsmInfo::X86ELFMCAsmInfo(const Triple &T) {
     74   if (T.getArch() == Triple::x86_64)
     75     PointerSize = 8;
     76 
     77   AssemblerDialect = AsmWriterFlavor;
     78 
     79   TextAlignFillValue = 0x90;
     80 
     81   PrivateGlobalPrefix = ".L";
     82   WeakRefDirective = "\t.weak\t";
     83   PCSymbol = ".";
     84 
     85   // Set up DWARF directives
     86   HasLEB128 = true;  // Target asm supports leb128 directives (little-endian)
     87 
     88   // Debug Information
     89   SupportsDebugInformation = true;
     90 
     91   // Exceptions handling
     92   ExceptionsType = ExceptionHandling::DwarfCFI;
     93 
     94   // OpenBSD and Bitrig have buggy support for .quad in 32-bit mode, just split
     95   // into two .words.
     96   if ((T.getOS() == Triple::OpenBSD || T.getOS() == Triple::Bitrig) &&
     97        T.getArch() == Triple::x86)
     98     Data64bitsDirective = 0;
     99 }
    100 
    101 const MCExpr *
    102 X86_64MCAsmInfoDarwin::getExprForPersonalitySymbol(const MCSymbol *Sym,
    103                                                    unsigned Encoding,
    104                                                    MCStreamer &Streamer) const {
    105   MCContext &Context = Streamer.getContext();
    106   const MCExpr *Res =
    107     MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_GOTPCREL, Context);
    108   const MCExpr *Four = MCConstantExpr::Create(4, Context);
    109   return MCBinaryExpr::CreateAdd(Res, Four, Context);
    110 }
    111 
    112 const MCSection *X86ELFMCAsmInfo::
    113 getNonexecutableStackSection(MCContext &Ctx) const {
    114   return Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS,
    115                            0, SectionKind::getMetadata());
    116 }
    117 
    118 void X86MCAsmInfoMicrosoft::anchor() { }
    119 
    120 X86MCAsmInfoMicrosoft::X86MCAsmInfoMicrosoft(const Triple &Triple) {
    121   if (Triple.getArch() == Triple::x86_64) {
    122     GlobalPrefix = "";
    123     PrivateGlobalPrefix = ".L";
    124   }
    125 
    126   AssemblerDialect = AsmWriterFlavor;
    127 
    128   TextAlignFillValue = 0x90;
    129 }
    130 
    131 void X86MCAsmInfoGNUCOFF::anchor() { }
    132 
    133 X86MCAsmInfoGNUCOFF::X86MCAsmInfoGNUCOFF(const Triple &Triple) {
    134   if (Triple.getArch() == Triple::x86_64) {
    135     GlobalPrefix = "";
    136     PrivateGlobalPrefix = ".L";
    137   }
    138 
    139   AssemblerDialect = AsmWriterFlavor;
    140 
    141   TextAlignFillValue = 0x90;
    142 
    143   // Exceptions handling
    144   ExceptionsType = ExceptionHandling::DwarfCFI;
    145 }
    146