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//===- lib/ReaderWriter/PECOFF/OrderPass.h -------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file \brief This pass sorts atoms by section name, so that they will appear
/// in the correct order in the output.
///
/// In COFF, sections will be merged into one section by the linker if their
/// names are the same after discarding the "$" character and all characters
/// follow it from their names. The characters following the "$" character
/// determines the merge order. Assume there's an object file containing four
/// data sections in the following order.
///
/// - .data$2
/// - .data$3
/// - .data$1
/// - .data
///
/// In this case, the resulting binary should have ".data" section with the
/// contents of ".data", ".data$1", ".data$2" and ".data$3" in that order.
///
//===----------------------------------------------------------------------===//
#ifndef LLD_READER_WRITER_PE_COFF_ORDER_PASS_H
#define LLD_READER_WRITER_PE_COFF_ORDER_PASS_H
#include "Atoms.h"
#include "lld/Core/Parallel.h"
#include "lld/Core/Pass.h"
#include <algorithm>
namespace lld {
namespace pecoff {
static bool compareByPosition(const DefinedAtom *lhs, const DefinedAtom *rhs) {
const File *lhsFile = &lhs->file();
const File *rhsFile = &rhs->file();
if (lhsFile->ordinal() != rhsFile->ordinal())
return lhsFile->ordinal() < rhsFile->ordinal();
return lhs->ordinal() < rhs->ordinal();
}
static bool compare(const DefinedAtom *lhs, const DefinedAtom *rhs) {
bool lhsCustom = (lhs->sectionChoice() == DefinedAtom::sectionCustomRequired);
bool rhsCustom = (rhs->sectionChoice() == DefinedAtom::sectionCustomRequired);
if (lhsCustom && rhsCustom) {
int cmp = lhs->customSectionName().compare(rhs->customSectionName());
if (cmp != 0)
return cmp < 0;
return compareByPosition(lhs, rhs);
}
if (lhsCustom && !rhsCustom)
return true;
if (!lhsCustom && rhsCustom)
return false;
return compareByPosition(lhs, rhs);
}
class OrderPass : public lld::Pass {
public:
void perform(std::unique_ptr<MutableFile> &file) override {
MutableFile::DefinedAtomRange defined = file->definedAtoms();
parallel_sort(defined.begin(), defined.end(), compare);
}
};
} // namespace pecoff
} // namespace lld
#endif
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