84 lines · cpp
1//===- OutputSegment.h -----------------------------------------*- C++ -*-===//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 "OutputSegment.h"10#include "InputChunks.h"11#include "lld/Common/Memory.h"12 13#define DEBUG_TYPE "lld"14 15using namespace llvm;16using namespace llvm::wasm;17 18namespace lld::wasm {19 20void OutputSegment::addInputSegment(InputChunk *inSeg) {21 alignment = std::max(alignment, inSeg->alignment);22 inputSegments.push_back(inSeg);23 size = llvm::alignTo(size, 1ULL << inSeg->alignment);24 LLVM_DEBUG(dbgs() << "addInputSegment: " << inSeg->name << " oname=" << name25 << " size=" << inSeg->getSize()26 << " align=" << inSeg->alignment << " at:" << size << "\n");27 inSeg->outputSeg = this;28 inSeg->outputSegmentOffset = size;29 size += inSeg->getSize();30}31 32// This function scans over the input segments.33//34// It removes MergeInputChunks from the input section array and adds35// new synthetic sections at the location of the first input section36// that it replaces. It then finalizes each synthetic section in order37// to compute an output offset for each piece of each input section.38void OutputSegment::finalizeInputSegments() {39 LLVM_DEBUG(llvm::dbgs() << "finalizeInputSegments: " << name << "\n");40 std::vector<SyntheticMergedChunk *> mergedSegments;41 std::vector<InputChunk *> newSegments;42 for (InputChunk *s : inputSegments) {43 MergeInputChunk *ms = dyn_cast<MergeInputChunk>(s);44 if (!ms) {45 newSegments.push_back(s);46 continue;47 }48 49 // A segment should not make it here unless its alive50 assert(ms->live);51 52 auto i = llvm::find_if(mergedSegments, [=](SyntheticMergedChunk *seg) {53 return seg->flags == ms->flags && seg->alignment == ms->alignment;54 });55 if (i == mergedSegments.end()) {56 LLVM_DEBUG(llvm::dbgs() << "new merge segment: " << name57 << " alignment=" << ms->alignment << "\n");58 auto *syn = make<SyntheticMergedChunk>(name, ms->alignment, ms->flags);59 syn->outputSeg = this;60 mergedSegments.push_back(syn);61 i = std::prev(mergedSegments.end());62 newSegments.push_back(syn);63 } else {64 LLVM_DEBUG(llvm::dbgs() << "adding to merge segment: " << name << "\n");65 }66 (*i)->addMergeChunk(ms);67 }68 69 for (auto *ms : mergedSegments)70 ms->finalizeContents();71 72 inputSegments = newSegments;73 size = 0;74 for (InputChunk *seg : inputSegments) {75 size = llvm::alignTo(size, 1ULL << seg->alignment);76 LLVM_DEBUG(llvm::dbgs() << "outputSegmentOffset set: " << seg->name77 << " -> " << size << "\n");78 seg->outputSegmentOffset = size;79 size += seg->getSize();80 }81}82 83} // namespace lld::wasm84