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      1 //===-- X86MCAsmInfo.cpp - X86 asm properties -----------------------------===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 //
      9 // This file contains the declarations of the X86MCAsmInfo properties.
     10 //
     11 //===----------------------------------------------------------------------===//
     12 
     13 #include "X86MCAsmInfo.h"
     14 #include "llvm/ADT/Triple.h"
     15 #include "llvm/MC/MCExpr.h"
     16 #include "llvm/MC/MCStreamer.h"
     17 #include "llvm/Support/CommandLine.h"
     18 using namespace llvm;
     19 
     20 enum AsmWriterFlavorTy {
     21   // Note: This numbering has to match the GCC assembler dialects for inline
     22   // asm alternatives to work right.
     23   ATT = 0, Intel = 1
     24 };
     25 
     26 static cl::opt<AsmWriterFlavorTy> AsmWriterFlavor(
     27     "x86-asm-syntax", cl::init(ATT), cl::Hidden,
     28     cl::desc("Choose style of code to emit from X86 backend:"),
     29     cl::values(clEnumValN(ATT, "att", "Emit AT&T-style assembly"),
     30                clEnumValN(Intel, "intel", "Emit Intel-style assembly")));
     31 
     32 static cl::opt<bool>
     33 MarkedJTDataRegions("mark-data-regions", cl::init(true),
     34   cl::desc("Mark code section jump table data regions."),
     35   cl::Hidden);
     36 
     37 void X86MCAsmInfoDarwin::anchor() { }
     38 
     39 X86MCAsmInfoDarwin::X86MCAsmInfoDarwin(const Triple &T) {
     40   bool is64Bit = T.getArch() == Triple::x86_64;
     41   if (is64Bit)
     42     CodePointerSize = CalleeSaveStackSlotSize = 8;
     43 
     44   AssemblerDialect = AsmWriterFlavor;
     45 
     46   TextAlignFillValue = 0x90;
     47 
     48   if (!is64Bit)
     49     Data64bitsDirective = nullptr;       // we can't emit a 64-bit unit
     50 
     51   // Use ## as a comment string so that .s files generated by llvm can go
     52   // through the GCC preprocessor without causing an error.  This is needed
     53   // because "clang foo.s" runs the C preprocessor, which is usually reserved
     54   // for .S files on other systems.  Perhaps this is because the file system
     55   // wasn't always case preserving or something.
     56   CommentString = "##";
     57 
     58   SupportsDebugInformation = true;
     59   UseDataRegionDirectives = MarkedJTDataRegions;
     60 
     61   // Exceptions handling
     62   ExceptionsType = ExceptionHandling::DwarfCFI;
     63 
     64   // old assembler lacks some directives
     65   // FIXME: this should really be a check on the assembler characteristics
     66   // rather than OS version
     67   if (T.isMacOSX() && T.isMacOSXVersionLT(10, 6))
     68     HasWeakDefCanBeHiddenDirective = false;
     69 
     70   // Assume ld64 is new enough that the abs-ified FDE relocs may be used
     71   // (actually, must, since otherwise the non-extern relocations we produce
     72   // overwhelm ld64's tiny little mind and it fails).
     73   DwarfFDESymbolsUseAbsDiff = true;
     74 }
     75 
     76 X86_64MCAsmInfoDarwin::X86_64MCAsmInfoDarwin(const Triple &Triple)
     77   : X86MCAsmInfoDarwin(Triple) {
     78 }
     79 
     80 void X86ELFMCAsmInfo::anchor() { }
     81 
     82 X86ELFMCAsmInfo::X86ELFMCAsmInfo(const Triple &T) {
     83   bool is64Bit = T.getArch() == Triple::x86_64;
     84   bool isX32 = T.getEnvironment() == Triple::GNUX32;
     85 
     86   // For ELF, x86-64 pointer size depends on the ABI.
     87   // For x86-64 without the x32 ABI, pointer size is 8. For x86 and for x86-64
     88   // with the x32 ABI, pointer size remains the default 4.
     89   CodePointerSize = (is64Bit && !isX32) ? 8 : 4;
     90 
     91   // OTOH, stack slot size is always 8 for x86-64, even with the x32 ABI.
     92   CalleeSaveStackSlotSize = is64Bit ? 8 : 4;
     93 
     94   AssemblerDialect = AsmWriterFlavor;
     95 
     96   TextAlignFillValue = 0x90;
     97 
     98   // Debug Information
     99   SupportsDebugInformation = true;
    100 
    101   // Exceptions handling
    102   ExceptionsType = ExceptionHandling::DwarfCFI;
    103 }
    104 
    105 const MCExpr *
    106 X86_64MCAsmInfoDarwin::getExprForPersonalitySymbol(const MCSymbol *Sym,
    107                                                    unsigned Encoding,
    108                                                    MCStreamer &Streamer) const {
    109   MCContext &Context = Streamer.getContext();
    110   const MCExpr *Res =
    111     MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, Context);
    112   const MCExpr *Four = MCConstantExpr::create(4, Context);
    113   return MCBinaryExpr::createAdd(Res, Four, Context);
    114 }
    115 
    116 void X86MCAsmInfoMicrosoft::anchor() { }
    117 
    118 X86MCAsmInfoMicrosoft::X86MCAsmInfoMicrosoft(const Triple &Triple) {
    119   if (Triple.getArch() == Triple::x86_64) {
    120     PrivateGlobalPrefix = ".L";
    121     PrivateLabelPrefix = ".L";
    122     CodePointerSize = 8;
    123     WinEHEncodingType = WinEH::EncodingType::Itanium;
    124   } else {
    125     // 32-bit X86 doesn't use CFI, so this isn't a real encoding type. It's just
    126     // a place holder that the Windows EHStreamer looks for to suppress CFI
    127     // output. In particular, usesWindowsCFI() returns false.
    128     WinEHEncodingType = WinEH::EncodingType::X86;
    129   }
    130 
    131   ExceptionsType = ExceptionHandling::WinEH;
    132 
    133   AssemblerDialect = AsmWriterFlavor;
    134 
    135   TextAlignFillValue = 0x90;
    136 
    137   AllowAtInName = true;
    138 }
    139 
    140 void X86MCAsmInfoMicrosoftMASM::anchor() { }
    141 
    142 X86MCAsmInfoMicrosoftMASM::X86MCAsmInfoMicrosoftMASM(const Triple &Triple)
    143     : X86MCAsmInfoMicrosoft(Triple) {
    144   DollarIsPC = true;
    145   SeparatorString = "\n";
    146   CommentString = ";";
    147   AllowQuestionAtStartOfIdentifier = true;
    148   AllowDollarAtStartOfIdentifier = true;
    149   AllowAtAtStartOfIdentifier = true;
    150 }
    151 
    152 void X86MCAsmInfoGNUCOFF::anchor() { }
    153 
    154 X86MCAsmInfoGNUCOFF::X86MCAsmInfoGNUCOFF(const Triple &Triple) {
    155   assert(Triple.isOSWindows() && "Windows is the only supported COFF target");
    156   if (Triple.getArch() == Triple::x86_64) {
    157     PrivateGlobalPrefix = ".L";
    158     PrivateLabelPrefix = ".L";
    159     CodePointerSize = 8;
    160     WinEHEncodingType = WinEH::EncodingType::Itanium;
    161     ExceptionsType = ExceptionHandling::WinEH;
    162   } else {
    163     ExceptionsType = ExceptionHandling::DwarfCFI;
    164   }
    165 
    166   AssemblerDialect = AsmWriterFlavor;
    167 
    168   TextAlignFillValue = 0x90;
    169 
    170   AllowAtInName = true;
    171 }
    172