X86MCAsmInfo.cpp revision cd81d94322a39503e4a3e87b6ee03d4fcb3465fb 
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 = nullptr;       // 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  // old assembler lacks some directives
70  // FIXME: this should really be a check on the assembler characteristics
71  // rather than OS version
72  if (T.isMacOSX() && T.isMacOSXVersionLT(10, 6))
73    HasWeakDefCanBeHiddenDirective = false;
74
75  // FIXME: this should not depend on the target OS version, but on the ld64
76  // version in use.  From at least >= ld64-97.17 (Xcode 3.2.6) the abs-ified
77  // FDE relocs may be used. We also use them for the ios simulator.
78  DwarfFDESymbolsUseAbsDiff = (T.isMacOSX() && !T.isMacOSXVersionLT(10, 6))
79    || T.isiOS();
80
81  UseIntegratedAssembler = true;
82}
83
84X86_64MCAsmInfoDarwin::X86_64MCAsmInfoDarwin(const Triple &Triple)
85  : X86MCAsmInfoDarwin(Triple) {
86}
87
88void X86ELFMCAsmInfo::anchor() { }
89
90X86ELFMCAsmInfo::X86ELFMCAsmInfo(const Triple &T) {
91  bool is64Bit = T.getArch() == Triple::x86_64;
92  bool isX32 = T.getEnvironment() == Triple::GNUX32;
93
94  // For ELF, x86-64 pointer size depends on the ABI.
95  // For x86-64 without the x32 ABI, pointer size is 8. For x86 and for x86-64
96  // with the x32 ABI, pointer size remains the default 4.
97  PointerSize = (is64Bit && !isX32) ? 8 : 4;
98
99  // OTOH, stack slot size is always 8 for x86-64, even with the x32 ABI.
100  CalleeSaveStackSlotSize = is64Bit ? 8 : 4;
101
102  AssemblerDialect = AsmWriterFlavor;
103
104  TextAlignFillValue = 0x90;
105
106  // Set up DWARF directives
107  HasLEB128 = true;  // Target asm supports leb128 directives (little-endian)
108
109  // Debug Information
110  SupportsDebugInformation = true;
111
112  // Exceptions handling
113  ExceptionsType = ExceptionHandling::DwarfCFI;
114
115  // OpenBSD and Bitrig have buggy support for .quad in 32-bit mode, just split
116  // into two .words.
117  if ((T.getOS() == Triple::OpenBSD || T.getOS() == Triple::Bitrig) &&
118       T.getArch() == Triple::x86)
119    Data64bitsDirective = nullptr;
120
121  // Always enable the integrated assembler by default.
122  // Clang also enabled it when the OS is Solaris but that is redundant here.
123  UseIntegratedAssembler = true;
124}
125
126const MCExpr *
127X86_64MCAsmInfoDarwin::getExprForPersonalitySymbol(const MCSymbol *Sym,
128                                                   unsigned Encoding,
129                                                   MCStreamer &Streamer) const {
130  MCContext &Context = Streamer.getContext();
131  const MCExpr *Res =
132    MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_GOTPCREL, Context);
133  const MCExpr *Four = MCConstantExpr::Create(4, Context);
134  return MCBinaryExpr::CreateAdd(Res, Four, Context);
135}
136
137const MCSection *X86ELFMCAsmInfo::
138getNonexecutableStackSection(MCContext &Ctx) const {
139  return Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS,
140                           0, SectionKind::getMetadata());
141}
142
143void X86MCAsmInfoMicrosoft::anchor() { }
144
145X86MCAsmInfoMicrosoft::X86MCAsmInfoMicrosoft(const Triple &Triple) {
146  if (Triple.getArch() == Triple::x86_64) {
147    PrivateGlobalPrefix = ".L";
148    PointerSize = 8;
149    ExceptionsType = ExceptionHandling::WinEH;
150  }
151
152  AssemblerDialect = AsmWriterFlavor;
153
154  TextAlignFillValue = 0x90;
155
156  AllowAtInName = true;
157
158  UseIntegratedAssembler = true;
159}
160
161void X86MCAsmInfoGNUCOFF::anchor() { }
162
163X86MCAsmInfoGNUCOFF::X86MCAsmInfoGNUCOFF(const Triple &Triple) {
164  assert(Triple.isOSWindows() && "Windows is the only supported COFF target");
165  if (Triple.getArch() == Triple::x86_64) {
166    PrivateGlobalPrefix = ".L";
167    PointerSize = 8;
168    ExceptionsType = ExceptionHandling::WinEH;
169  } else {
170    ExceptionsType = ExceptionHandling::DwarfCFI;
171  }
172
173  AssemblerDialect = AsmWriterFlavor;
174
175  TextAlignFillValue = 0x90;
176
177  UseIntegratedAssembler = true;
178}
179