X86MCAsmInfo.cpp revision 266715 
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"
22using namespace llvm;
23
24enum 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
30static cl::opt<AsmWriterFlavorTy>
31AsmWriterFlavor("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
37static cl::opt<bool>
38MarkedJTDataRegions("mark-data-regions", cl::init(false),
39  cl::desc("Mark code section jump table data regions."),
40  cl::Hidden);
41
42void X86MCAsmInfoDarwin::anchor() { }
43
44X86MCAsmInfoDarwin::X86MCAsmInfoDarwin(const Triple &T) {
45  bool is64Bit = T.getArch() == Triple::x86_64;
46  if (is64Bit)
47    PointerSize = CalleeSaveStackSlotSize = 8;
48
49  AssemblerDialect = AsmWriterFlavor;
50
51  TextAlignFillValue = 0x90;
52
53  if (!is64Bit)
54    Data64bitsDirective = 0;       // we can't emit a 64-bit unit
55
56  // Use ## as a comment string so that .s files generated by llvm can go
57  // through the GCC preprocessor without causing an error.  This is needed
58  // because "clang foo.s" runs the C preprocessor, which is usually reserved
59  // for .S files on other systems.  Perhaps this is because the file system
60  // wasn't always case preserving or something.
61  CommentString = "##";
62
63  SupportsDebugInformation = true;
64  UseDataRegionDirectives = MarkedJTDataRegions;
65
66  // Exceptions handling
67  ExceptionsType = ExceptionHandling::DwarfCFI;
68
69  // FIXME: this should not depend on the target OS version, but on the ld64
70  // version in use.  From at least >= ld64-97.17 (Xcode 3.2.6) the abs-ified
71  // FDE relocs may be used.
72  DwarfFDESymbolsUseAbsDiff = T.isMacOSX() && !T.isMacOSXVersionLT(10, 6);
73
74  // old assembler lacks some directives
75  // FIXME: this should really be a check on the assembler characteristics
76  // rather than OS version
77  if (T.isMacOSX() && T.isMacOSXVersionLT(10, 6))
78    HasWeakDefCanBeHiddenDirective = false;
79}
80
81X86_64MCAsmInfoDarwin::X86_64MCAsmInfoDarwin(const Triple &Triple)
82  : X86MCAsmInfoDarwin(Triple) {
83}
84
85void X86ELFMCAsmInfo::anchor() { }
86
87X86ELFMCAsmInfo::X86ELFMCAsmInfo(const Triple &T) {
88  bool is64Bit = T.getArch() == Triple::x86_64;
89  bool isX32 = T.getEnvironment() == Triple::GNUX32;
90
91  // For ELF, x86-64 pointer size depends on the ABI.
92  // For x86-64 without the x32 ABI, pointer size is 8. For x86 and for x86-64
93  // with the x32 ABI, pointer size remains the default 4.
94  PointerSize = (is64Bit && !isX32) ? 8 : 4;
95
96  // OTOH, stack slot size is always 8 for x86-64, even with the x32 ABI.
97  CalleeSaveStackSlotSize = is64Bit ? 8 : 4;
98
99  AssemblerDialect = AsmWriterFlavor;
100
101  TextAlignFillValue = 0x90;
102
103  PrivateGlobalPrefix = ".L";
104
105  // Set up DWARF directives
106  HasLEB128 = true;  // Target asm supports leb128 directives (little-endian)
107
108  // Debug Information
109  SupportsDebugInformation = true;
110
111  // Exceptions handling
112  ExceptionsType = ExceptionHandling::DwarfCFI;
113
114  // OpenBSD and Bitrig have buggy support for .quad in 32-bit mode, just split
115  // into two .words.
116  if ((T.getOS() == Triple::OpenBSD || T.getOS() == Triple::Bitrig) &&
117       T.getArch() == Triple::x86)
118    Data64bitsDirective = 0;
119}
120
121const MCExpr *
122X86_64MCAsmInfoDarwin::getExprForPersonalitySymbol(const MCSymbol *Sym,
123                                                   unsigned Encoding,
124                                                   MCStreamer &Streamer) const {
125  MCContext &Context = Streamer.getContext();
126  const MCExpr *Res =
127    MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_GOTPCREL, Context);
128  const MCExpr *Four = MCConstantExpr::Create(4, Context);
129  return MCBinaryExpr::CreateAdd(Res, Four, Context);
130}
131
132const MCSection *X86ELFMCAsmInfo::
133getNonexecutableStackSection(MCContext &Ctx) const {
134  return Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS,
135                           0, SectionKind::getMetadata());
136}
137
138void X86MCAsmInfoMicrosoft::anchor() { }
139
140X86MCAsmInfoMicrosoft::X86MCAsmInfoMicrosoft(const Triple &Triple) {
141  if (Triple.getArch() == Triple::x86_64) {
142    GlobalPrefix = "";
143    PrivateGlobalPrefix = ".L";
144  }
145
146  AssemblerDialect = AsmWriterFlavor;
147
148  TextAlignFillValue = 0x90;
149
150  AllowAtInName = true;
151}
152
153void X86MCAsmInfoGNUCOFF::anchor() { }
154
155X86MCAsmInfoGNUCOFF::X86MCAsmInfoGNUCOFF(const Triple &Triple) {
156  if (Triple.getArch() == Triple::x86_64) {
157    GlobalPrefix = "";
158    PrivateGlobalPrefix = ".L";
159  }
160
161  AssemblerDialect = AsmWriterFlavor;
162
163  TextAlignFillValue = 0x90;
164
165  // Exceptions handling
166  ExceptionsType = ExceptionHandling::DwarfCFI;
167}
168