| 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 | |
| 15 | using namespace llvm; |
| 16 | using namespace llvm::wasm; |
| 17 | |
| 18 | namespace lld::wasm { |
| 19 | |
| 20 | void OutputSegment::addInputSegment(InputChunk *inSeg) { |
| 21 | alignment = std::max(a: alignment, b: inSeg->alignment); |
| 22 | inputSegments.push_back(x: inSeg); |
| 23 | size = llvm::alignTo(Value: size, Align: 1ULL << inSeg->alignment); |
| 24 | LLVM_DEBUG(dbgs() << "addInputSegment: "<< inSeg->name << " oname="<< name |
| 25 | << " 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 adds |
| 35 | // new synthetic sections at the location of the first input section |
| 36 | // that it replaces. It then finalizes each synthetic section in order |
| 37 | // to compute an output offset for each piece of each input section. |
| 38 | void 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>(Val: s); |
| 44 | if (!ms) { |
| 45 | newSegments.push_back(x: s); |
| 46 | continue; |
| 47 | } |
| 48 | |
| 49 | // A segment should not make it here unless its alive |
| 50 | assert(ms->live); |
| 51 | |
| 52 | auto i = llvm::find_if(Range&: mergedSegments, P: [=](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: "<< name |
| 57 | << " alignment="<< ms->alignment << "\n"); |
| 58 | auto *syn = make<SyntheticMergedChunk>(args&: name, args&: ms->alignment, args&: ms->flags); |
| 59 | syn->outputSeg = this; |
| 60 | mergedSegments.push_back(x: syn); |
| 61 | i = std::prev(x: mergedSegments.end()); |
| 62 | newSegments.push_back(x: 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(Value: size, Align: 1ULL << seg->alignment); |
| 76 | LLVM_DEBUG(llvm::dbgs() << "outputSegmentOffset set: "<< seg->name |
| 77 | << " -> "<< size << "\n"); |
| 78 | seg->outputSegmentOffset = size; |
| 79 | size += seg->getSize(); |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | } // namespace lld::wasm |
| 84 |