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//===- OutputSegment.h -----------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "OutputSegment.h"
#include "InputChunks.h"
#include "lld/Common/Memory.h"
#define DEBUG_TYPE "lld"
using namespace llvm;
using namespace llvm::wasm;
namespace lld::wasm {
void OutputSegment::addInputSegment(InputChunk *inSeg) {
alignment = std::max(alignment, inSeg->alignment);
inputSegments.push_back(inSeg);
size = llvm::alignTo(size, 1ULL << inSeg->alignment);
LLVM_DEBUG(dbgs() << "addInputSegment: " << inSeg->name << " oname=" << name
<< " size=" << inSeg->getSize()
<< " align=" << inSeg->alignment << " at:" << size << "\n");
inSeg->outputSeg = this;
inSeg->outputSegmentOffset = size;
size += inSeg->getSize();
}
// This function scans over the input segments.
//
// It removes MergeInputChunks from the input section array and adds
// new synthetic sections at the location of the first input section
// that it replaces. It then finalizes each synthetic section in order
// to compute an output offset for each piece of each input section.
void OutputSegment::finalizeInputSegments() {
LLVM_DEBUG(llvm::dbgs() << "finalizeInputSegments: " << name << "\n");
std::vector<SyntheticMergedChunk *> mergedSegments;
std::vector<InputChunk *> newSegments;
for (InputChunk *s : inputSegments) {
MergeInputChunk *ms = dyn_cast<MergeInputChunk>(s);
if (!ms) {
newSegments.push_back(s);
continue;
}
// A segment should not make it here unless its alive
assert(ms->live);
auto i = llvm::find_if(mergedSegments, [=](SyntheticMergedChunk *seg) {
return seg->flags == ms->flags && seg->alignment == ms->alignment;
});
if (i == mergedSegments.end()) {
LLVM_DEBUG(llvm::dbgs() << "new merge segment: " << name
<< " alignment=" << ms->alignment << "\n");
auto *syn = make<SyntheticMergedChunk>(name, ms->alignment, ms->flags);
syn->outputSeg = this;
mergedSegments.push_back(syn);
i = std::prev(mergedSegments.end());
newSegments.push_back(syn);
} else {
LLVM_DEBUG(llvm::dbgs() << "adding to merge segment: " << name << "\n");
}
(*i)->addMergeChunk(ms);
}
for (auto *ms : mergedSegments)
ms->finalizeContents();
inputSegments = newSegments;
size = 0;
for (InputChunk *seg : inputSegments) {
size = llvm::alignTo(size, 1ULL << seg->alignment);
LLVM_DEBUG(llvm::dbgs() << "outputSegmentOffset set: " << seg->name
<< " -> " << size << "\n");
seg->outputSegmentOffset = size;
size += seg->getSize();
}
}
} // namespace lld::wasm
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