1//===- lib/MC/MCSection.cpp - Machine Code Section Representation ---------===//
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#include "llvm/MC/MCSection.h"
10#include "llvm/ADT/SmallVector.h"
11#include "llvm/Config/llvm-config.h"
12#include "llvm/MC/MCContext.h"
13#include "llvm/MC/MCSymbol.h"
14#include "llvm/Support/Compiler.h"
15#include "llvm/Support/ErrorHandling.h"
16#include "llvm/Support/raw_ostream.h"
17#include <utility>
18
19using namespace llvm;
20
21MCSection::MCSection(StringRef Name, bool IsText, bool IsBss, MCSymbol *Begin)
22 : Begin(Begin), HasInstructions(false), IsRegistered(false), IsText(IsText),
23 IsBss(IsBss), Name(Name) {
24 DummyFragment.setParent(this);
25}
26
27MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) {
28 if (!End)
29 End = Ctx.createTempSymbol(Name: "sec_end");
30 return End;
31}
32
33Align MCSection::getAlignmentForObjectFile(uint64_t Size) const {
34 if (Size < getAlign().value())
35 return getAlign();
36
37 if (Size < getPreferredAlignment().value())
38 return Align(NextPowerOf2(A: Size - 1));
39
40 return getPreferredAlignment();
41}
42
43bool MCSection::hasEnded() const { return End && End->isInSection(); }
44
45#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
46LLVM_DUMP_METHOD void MCSection::dump(
47 DenseMap<const MCFragment *, SmallVector<const MCSymbol *, 0>> *FragToSyms)
48 const {
49 raw_ostream &OS = errs();
50
51 OS << "MCSection Name:" << getName();
52 if (isLinkerRelaxable())
53 OS << " FirstLinkerRelaxable:" << firstLinkerRelaxable();
54 for (auto &F : *this) {
55 OS << '\n';
56 F.dump();
57 if (!FragToSyms)
58 continue;
59 auto It = FragToSyms->find(&F);
60 if (It == FragToSyms->end())
61 continue;
62 for (auto *Sym : It->second) {
63 OS << "\n Symbol @" << Sym->getOffset() << ' ' << Sym->getName();
64 if (Sym->isTemporary())
65 OS << " Temporary";
66 }
67 }
68}
69#endif
70
71void MCFragment::setVarContents(ArrayRef<char> Contents) {
72 auto &S = getParent()->ContentStorage;
73 if (VarContentStart + Contents.size() > VarContentEnd) {
74 VarContentStart = S.size();
75 S.resize_for_overwrite(N: S.size() + Contents.size());
76 }
77 VarContentEnd = VarContentStart + Contents.size();
78 llvm::copy(Range&: Contents, Out: S.begin() + VarContentStart);
79}
80
81void MCFragment::addFixup(MCFixup Fixup) { appendFixups(Fixups: {Fixup}); }
82
83void MCFragment::appendFixups(ArrayRef<MCFixup> Fixups) {
84 auto &S = getParent()->FixupStorage;
85 if (LLVM_UNLIKELY(FixupEnd != S.size())) {
86 // Move the elements to the end. Reserve space to avoid invalidating
87 // S.begin()+I for `append`.
88 auto Size = FixupEnd - FixupStart;
89 auto I = std::exchange(obj&: FixupStart, new_val: S.size());
90 S.reserve(N: S.size() + Size);
91 S.append(in_start: S.begin() + I, in_end: S.begin() + I + Size);
92 }
93 S.append(in_start: Fixups.begin(), in_end: Fixups.end());
94 FixupEnd = S.size();
95}
96
97void MCFragment::setVarFixups(ArrayRef<MCFixup> Fixups) {
98 assert(Fixups.size() < 256 &&
99 "variable-size tail cannot have more than 256 fixups");
100 auto &S = getParent()->FixupStorage;
101 if (Fixups.size() > VarFixupSize) {
102 VarFixupStart = S.size();
103 S.resize_for_overwrite(N: S.size() + Fixups.size());
104 }
105 VarFixupSize = Fixups.size();
106 // Source fixup offsets are relative to the variable part's start. Add the
107 // fixed part size to make them relative to the fixed part's start.
108 std::transform(first: Fixups.begin(), last: Fixups.end(), result: S.begin() + VarFixupStart,
109 unary_op: [Fixed = getFixedSize()](MCFixup F) {
110 F.setOffset(Fixed + F.getOffset());
111 return F;
112 });
113}
114