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| 1 | +//===- BPSectionOrderer.cpp -----------------------------------------------===// |
| 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 "BPSectionOrderer.h" |
| 10 | +#include "InputFiles.h" |
| 11 | +#include "InputSection.h" |
| 12 | +#include "SymbolTable.h" |
| 13 | +#include "Symbols.h" |
| 14 | +#include "lld/Common/BPSectionOrdererBase.inc" |
| 15 | +#include "llvm/Support/Endian.h" |
| 16 | + |
| 17 | +using namespace llvm; |
| 18 | +using namespace lld::elf; |
| 19 | + |
| 20 | +namespace { |
| 21 | +struct BPOrdererELF; |
| 22 | +} |
| 23 | +template <> struct lld::BPOrdererTraits<struct BPOrdererELF> { |
| 24 | + using Section = elf::InputSectionBase; |
| 25 | + using Defined = elf::Defined; |
| 26 | +}; |
| 27 | +namespace { |
| 28 | +struct BPOrdererELF : lld::BPOrderer<BPOrdererELF> { |
| 29 | + DenseMap<const InputSectionBase *, Defined *> secToSym; |
| 30 | + |
| 31 | + static uint64_t getSize(const Section &sec) { return sec.getSize(); } |
| 32 | + static bool isCodeSection(const Section &sec) { |
| 33 | + return sec.flags & ELF::SHF_EXECINSTR; |
| 34 | + } |
| 35 | + ArrayRef<Defined *> getSymbols(const Section &sec) { |
| 36 | + auto it = secToSym.find(&sec); |
| 37 | + if (it == secToSym.end()) |
| 38 | + return {}; |
| 39 | + return ArrayRef(it->second); |
| 40 | + } |
| 41 | + |
| 42 | + static void |
| 43 | + getSectionHashes(const Section &sec, SmallVectorImpl<uint64_t> &hashes, |
| 44 | + const DenseMap<const void *, uint64_t> §ionToIdx) { |
| 45 | + constexpr unsigned windowSize = 4; |
| 46 | + |
| 47 | + // Calculate content hashes: k-mers and the last k-1 bytes. |
| 48 | + ArrayRef<uint8_t> data = sec.content(); |
| 49 | + if (data.size() >= windowSize) |
| 50 | + for (size_t i = 0; i <= data.size() - windowSize; ++i) |
| 51 | + hashes.push_back(support::endian::read32le(data.data() + i)); |
| 52 | + for (uint8_t byte : data.take_back(windowSize - 1)) |
| 53 | + hashes.push_back(byte); |
| 54 | + |
| 55 | + llvm::sort(hashes); |
| 56 | + hashes.erase(std::unique(hashes.begin(), hashes.end()), hashes.end()); |
| 57 | + } |
| 58 | + |
| 59 | + static StringRef getSymName(const Defined &sym) { return sym.getName(); } |
| 60 | + static uint64_t getSymValue(const Defined &sym) { return sym.value; } |
| 61 | + static uint64_t getSymSize(const Defined &sym) { return sym.size; } |
| 62 | +}; |
| 63 | +} // namespace |
| 64 | + |
| 65 | +DenseMap<const InputSectionBase *, int> elf::runBalancedPartitioning( |
| 66 | + Ctx &ctx, StringRef profilePath, bool forFunctionCompression, |
| 67 | + bool forDataCompression, bool compressionSortStartupFunctions, |
| 68 | + bool verbose) { |
| 69 | + // Collect candidate sections and associated symbols. |
| 70 | + SmallVector<InputSectionBase *> sections; |
| 71 | + DenseMap<CachedHashStringRef, std::set<unsigned>> rootSymbolToSectionIdxs; |
| 72 | + BPOrdererELF orderer; |
| 73 | + |
| 74 | + auto addSection = [&](Symbol &sym) { |
| 75 | + auto *d = dyn_cast<Defined>(&sym); |
| 76 | + if (!d) |
| 77 | + return; |
| 78 | + auto *sec = dyn_cast_or_null<InputSectionBase>(d->section); |
| 79 | + if (!sec || sec->size == 0 || !orderer.secToSym.try_emplace(sec, d).second) |
| 80 | + return; |
| 81 | + rootSymbolToSectionIdxs[CachedHashStringRef(getRootSymbol(sym.getName()))] |
| 82 | + .insert(sections.size()); |
| 83 | + sections.emplace_back(sec); |
| 84 | + }; |
| 85 | + |
| 86 | + for (Symbol *sym : ctx.symtab->getSymbols()) |
| 87 | + addSection(*sym); |
| 88 | + for (ELFFileBase *file : ctx.objectFiles) |
| 89 | + for (Symbol *sym : file->getLocalSymbols()) |
| 90 | + addSection(*sym); |
| 91 | + return orderer.computeOrder(profilePath, forFunctionCompression, |
| 92 | + forDataCompression, |
| 93 | + compressionSortStartupFunctions, verbose, |
| 94 | + sections, rootSymbolToSectionIdxs); |
| 95 | +} |
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