1 //===- MCAsmInfo.cpp - Asm Info -------------------------------------------===//
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 defines target asm properties related what form asm statements
10 // should take.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/MC/MCAsmInfo.h"
15 #include "llvm/ADT/StringExtras.h"
16 #include "llvm/BinaryFormat/Dwarf.h"
17 #include "llvm/MC/MCContext.h"
18 #include "llvm/MC/MCExpr.h"
19 #include "llvm/MC/MCStreamer.h"
20 #include "llvm/Support/CommandLine.h"
21 
22 using namespace llvm;
23 
24 namespace {
25 enum DefaultOnOff { Default, Enable, Disable };
26 }
27 static cl::opt<DefaultOnOff> DwarfExtendedLoc(
28     "dwarf-extended-loc", cl::Hidden,
29     cl::desc("Disable emission of the extended flags in .loc directives."),
30     cl::values(clEnumVal(Default, "Default for platform"),
31                clEnumVal(Enable, "Enabled"), clEnumVal(Disable, "Disabled")),
32     cl::init(Default));
33 
34 namespace llvm {
35 cl::opt<cl::boolOrDefault> UseLEB128Directives(
36     "use-leb128-directives", cl::Hidden,
37     cl::desc(
38         "Disable the usage of LEB128 directives, and generate .byte instead."),
39     cl::init(cl::BOU_UNSET));
40 }
41 
42 MCAsmInfo::MCAsmInfo() {
43   SeparatorString = ";";
44   CommentString = "#";
45   LabelSuffix = ":";
46   PrivateGlobalPrefix = "L";
47   PrivateLabelPrefix = PrivateGlobalPrefix;
48   LinkerPrivateGlobalPrefix = "";
49   InlineAsmStart = "APP";
50   InlineAsmEnd = "NO_APP";
51   Code16Directive = ".code16";
52   Code32Directive = ".code32";
53   Code64Directive = ".code64";
54   ZeroDirective = "\t.zero\t";
55   AsciiDirective = "\t.ascii\t";
56   AscizDirective = "\t.asciz\t";
57   Data8bitsDirective = "\t.byte\t";
58   Data16bitsDirective = "\t.short\t";
59   Data32bitsDirective = "\t.long\t";
60   Data64bitsDirective = "\t.quad\t";
61   GlobalDirective = "\t.globl\t";
62   WeakDirective = "\t.weak\t";
63   if (DwarfExtendedLoc != Default)
64     SupportsExtendedDwarfLocDirective = DwarfExtendedLoc == Enable;
65   if (UseLEB128Directives != cl::BOU_UNSET)
66     HasLEB128Directives = UseLEB128Directives == cl::BOU_TRUE;
67   UseIntegratedAssembler = true;
68   ParseInlineAsmUsingAsmParser = false;
69   PreserveAsmComments = true;
70   PPCUseFullRegisterNames = false;
71 }
72 
73 MCAsmInfo::~MCAsmInfo() = default;
74 
75 void MCAsmInfo::addInitialFrameState(const MCCFIInstruction &Inst) {
76   InitialFrameState.push_back(Inst);
77 }
78 
79 bool MCAsmInfo::isSectionAtomizableBySymbols(const MCSection &Section) const {
80   return false;
81 }
82 
83 const MCExpr *
84 MCAsmInfo::getExprForPersonalitySymbol(const MCSymbol *Sym,
85                                        unsigned Encoding,
86                                        MCStreamer &Streamer) const {
87   return getExprForFDESymbol(Sym, Encoding, Streamer);
88 }
89 
90 const MCExpr *
91 MCAsmInfo::getExprForFDESymbol(const MCSymbol *Sym,
92                                unsigned Encoding,
93                                MCStreamer &Streamer) const {
94   if (!(Encoding & dwarf::DW_EH_PE_pcrel))
95     return MCSymbolRefExpr::create(Sym, Streamer.getContext());
96 
97   MCContext &Context = Streamer.getContext();
98   const MCExpr *Res = MCSymbolRefExpr::create(Sym, Context);
99   MCSymbol *PCSym = Context.createTempSymbol();
100   Streamer.emitLabel(PCSym);
101   const MCExpr *PC = MCSymbolRefExpr::create(PCSym, Context);
102   return MCBinaryExpr::createSub(Res, PC, Context);
103 }
104 
105 bool MCAsmInfo::isAcceptableChar(char C) const {
106   if (C == '@')
107     return doesAllowAtInName();
108 
109   return isAlnum(C) || C == '_' || C == '$' || C == '.';
110 }
111 
112 bool MCAsmInfo::isValidUnquotedName(StringRef Name) const {
113   if (Name.empty())
114     return false;
115 
116   // If any of the characters in the string is an unacceptable character, force
117   // quotes.
118   for (char C : Name) {
119     if (!isAcceptableChar(C))
120       return false;
121   }
122 
123   return true;
124 }
125 
126 bool MCAsmInfo::shouldOmitSectionDirective(StringRef SectionName) const {
127   // FIXME: Does .section .bss/.data/.text work everywhere??
128   return SectionName == ".text" || SectionName == ".data" ||
129         (SectionName == ".bss" && !usesELFSectionDirectiveForBSS());
130 }
131