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-exception 6// 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 { 19 20namespace wasm { 21 22void OutputSegment::addInputSegment(InputChunk *inSeg) { 23 alignment = std::max(alignment, inSeg->alignment); 24 inputSegments.push_back(inSeg); 25 size = llvm::alignTo(size, 1ULL << inSeg->alignment); 26 LLVM_DEBUG(dbgs() << "addInputSegment: " << inSeg->name << " oname=" << name 27 << " size=" << inSeg->getSize() 28 << " align=" << inSeg->alignment << " at:" << size << "\n"); 29 inSeg->outputSeg = this; 30 inSeg->outputSegmentOffset = size; 31 size += inSeg->getSize(); 32} 33 34// This function scans over the input segments. 35// 36// It removes MergeInputChunks from the input section array and adds 37// new synthetic sections at the location of the first input section 38// that it replaces. It then finalizes each synthetic section in order 39// to compute an output offset for each piece of each input section. 40void OutputSegment::finalizeInputSegments() { 41 LLVM_DEBUG(llvm::dbgs() << "finalizeInputSegments: " << name << "\n"); 42 std::vector<SyntheticMergedChunk *> mergedSegments; 43 std::vector<InputChunk *> newSegments; 44 for (InputChunk *s : inputSegments) { 45 MergeInputChunk *ms = dyn_cast<MergeInputChunk>(s); 46 if (!ms) { 47 newSegments.push_back(s); 48 continue; 49 } 50 51 // A segment should not make it here unless its alive 52 assert(ms->live); 53 54 auto i = llvm::find_if(mergedSegments, [=](SyntheticMergedChunk *seg) { 55 return seg->flags == ms->flags && seg->alignment == ms->alignment; 56 }); 57 if (i == mergedSegments.end()) { 58 LLVM_DEBUG(llvm::dbgs() << "new merge segment: " << name 59 << " alignment=" << ms->alignment << "\n"); 60 auto *syn = make<SyntheticMergedChunk>(name, ms->alignment, ms->flags); 61 syn->outputSeg = this; 62 mergedSegments.push_back(syn); 63 i = std::prev(mergedSegments.end()); 64 newSegments.push_back(syn); 65 } else { 66 LLVM_DEBUG(llvm::dbgs() << "adding to merge segment: " << name << "\n"); 67 } 68 (*i)->addMergeChunk(ms); 69 } 70 71 for (auto *ms : mergedSegments) 72 ms->finalizeContents(); 73 74 inputSegments = newSegments; 75 size = 0; 76 for (InputChunk *seg : inputSegments) { 77 size = llvm::alignTo(size, 1ULL << seg->alignment); 78 LLVM_DEBUG(llvm::dbgs() << "outputSegmentOffset set: " << seg->name 79 << " -> " << size << "\n"); 80 seg->outputSegmentOffset = size; 81 size += seg->getSize(); 82 } 83} 84 85} // namespace wasm 86} // namespace lld 87