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 static cl::opt<bool>
38 MarkedJTDataRegions("mark-data-regions", cl::init(false),
39 cl::desc("Mark code section jump table data regions."),
40 cl::Hidden);
41
anchor()42 void X86MCAsmInfoDarwin::anchor() { }
43
X86MCAsmInfoDarwin(const Triple & T)44 X86MCAsmInfoDarwin::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
X86_64MCAsmInfoDarwin(const Triple & Triple)84 X86_64MCAsmInfoDarwin::X86_64MCAsmInfoDarwin(const Triple &Triple)
85 : X86MCAsmInfoDarwin(Triple) {
86 }
87
anchor()88 void X86ELFMCAsmInfo::anchor() { }
89
X86ELFMCAsmInfo(const Triple & T)90 X86ELFMCAsmInfo::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
126 const MCExpr *
getExprForPersonalitySymbol(const MCSymbol * Sym,unsigned Encoding,MCStreamer & Streamer) const127 X86_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
137 const MCSection *X86ELFMCAsmInfo::
getNonexecutableStackSection(MCContext & Ctx) const138 getNonexecutableStackSection(MCContext &Ctx) const {
139 return Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS,
140 0, SectionKind::getMetadata());
141 }
142
anchor()143 void X86MCAsmInfoMicrosoft::anchor() { }
144
X86MCAsmInfoMicrosoft(const Triple & Triple)145 X86MCAsmInfoMicrosoft::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
anchor()161 void X86MCAsmInfoGNUCOFF::anchor() { }
162
X86MCAsmInfoGNUCOFF(const Triple & Triple)163 X86MCAsmInfoGNUCOFF::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