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/MC/MCValue.h"
21#include "llvm/Support/Casting.h"
22#include "llvm/Support/CommandLine.h"
23
24using namespace llvm;
25
26namespace {
27enum DefaultOnOff { Default, Enable, Disable };
28}
29static cl::opt<DefaultOnOff> DwarfExtendedLoc(
30 "dwarf-extended-loc", cl::Hidden,
31 cl::desc("Disable emission of the extended flags in .loc directives."),
32 cl::values(clEnumVal(Default, "Default for platform"),
33 clEnumVal(Enable, "Enabled"), clEnumVal(Disable, "Disabled")),
34 cl::init(Val: Default));
35
36namespace llvm {
37cl::opt<cl::boolOrDefault> UseLEB128Directives(
38 "use-leb128-directives", cl::Hidden,
39 cl::desc(
40 "Disable the usage of LEB128 directives, and generate .byte instead."),
41 cl::init(Val: cl::BOU_UNSET));
42}
43
44MCAsmInfo::MCAsmInfo() {
45 if (DwarfExtendedLoc != Default)
46 SupportsExtendedDwarfLocDirective = DwarfExtendedLoc == Enable;
47 if (UseLEB128Directives != cl::BOU_UNSET)
48 HasLEB128Directives = UseLEB128Directives == cl::BOU_TRUE;
49}
50
51MCAsmInfo::~MCAsmInfo() = default;
52
53void MCAsmInfo::addInitialFrameState(const MCCFIInstruction &Inst) {
54 InitialFrameState.push_back(x: Inst);
55}
56
57const MCExpr *
58MCAsmInfo::getExprForPersonalitySymbol(const MCSymbol *Sym,
59 unsigned Encoding,
60 MCStreamer &Streamer) const {
61 return getExprForFDESymbol(Sym, Encoding, Streamer);
62}
63
64const MCExpr *
65MCAsmInfo::getExprForFDESymbol(const MCSymbol *Sym,
66 unsigned Encoding,
67 MCStreamer &Streamer) const {
68 if (!(Encoding & dwarf::DW_EH_PE_pcrel))
69 return MCSymbolRefExpr::create(Symbol: Sym, Ctx&: Streamer.getContext());
70
71 MCContext &Context = Streamer.getContext();
72 const MCExpr *Res = MCSymbolRefExpr::create(Symbol: Sym, Ctx&: Context);
73 MCSymbol *PCSym = Context.createTempSymbol();
74 Streamer.emitLabel(Symbol: PCSym);
75 const MCExpr *PC = MCSymbolRefExpr::create(Symbol: PCSym, Ctx&: Context);
76 return MCBinaryExpr::createSub(LHS: Res, RHS: PC, Ctx&: Context);
77}
78
79bool MCAsmInfo::isAcceptableChar(char C) const {
80 if (C == '@')
81 return doesAllowAtInName();
82
83 return isAlnum(C) || C == '_' || C == '$' || C == '.';
84}
85
86bool MCAsmInfo::isValidUnquotedName(StringRef Name) const {
87 if (Name.empty())
88 return false;
89
90 // If any of the characters in the string is an unacceptable character, force
91 // quotes.
92 for (char C : Name) {
93 if (!isAcceptableChar(C))
94 return false;
95 }
96
97 return true;
98}
99
100bool MCAsmInfo::shouldOmitSectionDirective(StringRef SectionName) const {
101 // FIXME: Does .section .bss/.data/.text work everywhere??
102 return SectionName == ".text" || SectionName == ".data" ||
103 (SectionName == ".bss" && !usesELFSectionDirectiveForBSS());
104}
105
106void MCAsmInfo::initializeAtSpecifiers(ArrayRef<AtSpecifier> Descs) {
107 assert(AtSpecifierToName.empty() && "cannot initialize twice");
108 UseAtForSpecifier = true;
109 for (auto Desc : Descs) {
110 [[maybe_unused]] auto It =
111 AtSpecifierToName.try_emplace(Key: Desc.Kind, Args&: Desc.Name);
112 assert(It.second && "duplicate Kind");
113 [[maybe_unused]] auto It2 =
114 NameToAtSpecifier.try_emplace(Key: Desc.Name.lower(), Args&: Desc.Kind);
115 assert(It2.second);
116 }
117}
118
119StringRef MCAsmInfo::getSpecifierName(uint32_t S) const {
120 auto It = AtSpecifierToName.find(Val: S);
121 assert(It != AtSpecifierToName.end() &&
122 "ensure the specifier is set in initializeVariantKinds");
123 return It->second;
124}
125
126std::optional<uint32_t> MCAsmInfo::getSpecifierForName(StringRef Name) const {
127 auto It = NameToAtSpecifier.find(Key: Name.lower());
128 if (It != NameToAtSpecifier.end())
129 return It->second;
130 return {};
131}
132
133void MCAsmInfo::printExpr(raw_ostream &OS, const MCExpr &Expr) const {
134 if (auto *SE = dyn_cast<MCSpecifierExpr>(Val: &Expr))
135 printSpecifierExpr(OS, *SE);
136 else
137 Expr.print(OS, MAI: this);
138}
139
140bool MCAsmInfo::evaluateAsRelocatableImpl(const MCSpecifierExpr &E,
141 MCValue &Res,
142 const MCAssembler *Asm) const {
143 if (!E.getSubExpr()->evaluateAsRelocatable(Res, Asm))
144 return false;
145
146 Res.setSpecifier(E.getSpecifier());
147 return !Res.getSubSym();
148}
149