X86MCAsmInfo.cpp revision 360784 
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"
18using namespace llvm;
19
20enum 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
26static 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
32static cl::opt<bool>
33MarkedJTDataRegions("mark-data-regions", cl::init(true),
34  cl::desc("Mark code section jump table data regions."),
35  cl::Hidden);
36
37void X86MCAsmInfoDarwin::anchor() { }
38
39X86MCAsmInfoDarwin::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  UseIntegratedAssembler = true;
76}
77
78X86_64MCAsmInfoDarwin::X86_64MCAsmInfoDarwin(const Triple &Triple)
79  : X86MCAsmInfoDarwin(Triple) {
80}
81
82void X86ELFMCAsmInfo::anchor() { }
83
84X86ELFMCAsmInfo::X86ELFMCAsmInfo(const Triple &T) {
85  bool is64Bit = T.getArch() == Triple::x86_64;
86  bool isX32 = T.getEnvironment() == Triple::GNUX32;
87
88  // For ELF, x86-64 pointer size depends on the ABI.
89  // For x86-64 without the x32 ABI, pointer size is 8. For x86 and for x86-64
90  // with the x32 ABI, pointer size remains the default 4.
91  CodePointerSize = (is64Bit && !isX32) ? 8 : 4;
92
93  // OTOH, stack slot size is always 8 for x86-64, even with the x32 ABI.
94  CalleeSaveStackSlotSize = is64Bit ? 8 : 4;
95
96  AssemblerDialect = AsmWriterFlavor;
97
98  TextAlignFillValue = 0x90;
99
100  // Debug Information
101  SupportsDebugInformation = true;
102
103  // Exceptions handling
104  ExceptionsType = ExceptionHandling::DwarfCFI;
105
106  // Always enable the integrated assembler by default.
107  // Clang also enabled it when the OS is Solaris but that is redundant here.
108  UseIntegratedAssembler = true;
109}
110
111const MCExpr *
112X86_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
122void X86MCAsmInfoMicrosoft::anchor() { }
123
124X86MCAsmInfoMicrosoft::X86MCAsmInfoMicrosoft(const Triple &Triple) {
125  if (Triple.getArch() == Triple::x86_64) {
126    PrivateGlobalPrefix = ".L";
127    PrivateLabelPrefix = ".L";
128    CodePointerSize = 8;
129    WinEHEncodingType = WinEH::EncodingType::Itanium;
130  } else {
131    // 32-bit X86 doesn't use CFI, so this isn't a real encoding type. It's just
132    // a place holder that the Windows EHStreamer looks for to suppress CFI
133    // output. In particular, usesWindowsCFI() returns false.
134    WinEHEncodingType = WinEH::EncodingType::X86;
135  }
136
137  ExceptionsType = ExceptionHandling::WinEH;
138
139  AssemblerDialect = AsmWriterFlavor;
140
141  TextAlignFillValue = 0x90;
142
143  AllowAtInName = true;
144
145  UseIntegratedAssembler = true;
146}
147
148void X86MCAsmInfoGNUCOFF::anchor() { }
149
150X86MCAsmInfoGNUCOFF::X86MCAsmInfoGNUCOFF(const Triple &Triple) {
151  assert(Triple.isOSWindows() && "Windows is the only supported COFF target");
152  if (Triple.getArch() == Triple::x86_64) {
153    PrivateGlobalPrefix = ".L";
154    PrivateLabelPrefix = ".L";
155    CodePointerSize = 8;
156    WinEHEncodingType = WinEH::EncodingType::Itanium;
157    ExceptionsType = ExceptionHandling::WinEH;
158  } else {
159    ExceptionsType = ExceptionHandling::DwarfCFI;
160  }
161
162  AssemblerDialect = AsmWriterFlavor;
163
164  TextAlignFillValue = 0x90;
165
166  AllowAtInName = true;
167
168  UseIntegratedAssembler = true;
169}
170