104 lines · cpp
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-exception6//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("sec_end");30 return End;31}32 33bool MCSection::hasEnded() const { return End && End->isInSection(); }34 35#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)36LLVM_DUMP_METHOD void MCSection::dump(37 DenseMap<const MCFragment *, SmallVector<const MCSymbol *, 0>> *FragToSyms)38 const {39 raw_ostream &OS = errs();40 41 OS << "MCSection Name:" << getName();42 if (isLinkerRelaxable())43 OS << " FirstLinkerRelaxable:" << firstLinkerRelaxable();44 for (auto &F : *this) {45 OS << '\n';46 F.dump();47 if (!FragToSyms)48 continue;49 auto It = FragToSyms->find(&F);50 if (It == FragToSyms->end())51 continue;52 for (auto *Sym : It->second) {53 OS << "\n Symbol @" << Sym->getOffset() << ' ' << Sym->getName();54 if (Sym->isTemporary())55 OS << " Temporary";56 }57 }58}59#endif60 61void MCFragment::setVarContents(ArrayRef<char> Contents) {62 auto &S = getParent()->ContentStorage;63 if (VarContentStart + Contents.size() > VarContentEnd) {64 VarContentStart = S.size();65 S.resize_for_overwrite(S.size() + Contents.size());66 }67 VarContentEnd = VarContentStart + Contents.size();68 llvm::copy(Contents, S.begin() + VarContentStart);69}70 71void MCFragment::addFixup(MCFixup Fixup) { appendFixups({Fixup}); }72 73void MCFragment::appendFixups(ArrayRef<MCFixup> Fixups) {74 auto &S = getParent()->FixupStorage;75 if (LLVM_UNLIKELY(FixupEnd != S.size())) {76 // Move the elements to the end. Reserve space to avoid invalidating77 // S.begin()+I for `append`.78 auto Size = FixupEnd - FixupStart;79 auto I = std::exchange(FixupStart, S.size());80 S.reserve(S.size() + Size);81 S.append(S.begin() + I, S.begin() + I + Size);82 }83 S.append(Fixups.begin(), Fixups.end());84 FixupEnd = S.size();85}86 87void MCFragment::setVarFixups(ArrayRef<MCFixup> Fixups) {88 assert(Fixups.size() < 256 &&89 "variable-size tail cannot have more than 256 fixups");90 auto &S = getParent()->FixupStorage;91 if (Fixups.size() > VarFixupSize) {92 VarFixupStart = S.size();93 S.resize_for_overwrite(S.size() + Fixups.size());94 }95 VarFixupSize = Fixups.size();96 // Source fixup offsets are relative to the variable part's start. Add the97 // fixed part size to make them relative to the fixed part's start.98 std::transform(Fixups.begin(), Fixups.end(), S.begin() + VarFixupStart,99 [Fixed = getFixedSize()](MCFixup F) {100 F.setOffset(Fixed + F.getOffset());101 return F;102 });103}104