129 lines
4.7 KiB
C++
129 lines
4.7 KiB
C++
//===- llvm/CodeGen/DwarfStringPool.cpp - Dwarf Debug Framework -----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "DwarfStringPool.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCStreamer.h"
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#include <cassert>
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#include <utility>
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using namespace llvm;
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DwarfStringPool::DwarfStringPool(BumpPtrAllocator &A, AsmPrinter &Asm,
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StringRef Prefix)
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: Pool(A), Prefix(Prefix),
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ShouldCreateSymbols(Asm.MAI->doesDwarfUseRelocationsAcrossSections()) {}
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StringMapEntry<DwarfStringPool::EntryTy> &
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DwarfStringPool::getEntryImpl(AsmPrinter &Asm, StringRef Str) {
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auto I = Pool.insert(std::make_pair(Str, EntryTy()));
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auto &Entry = I.first->second;
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if (I.second) {
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Entry.Index = EntryTy::NotIndexed;
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Entry.Offset = NumBytes;
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Entry.Symbol = ShouldCreateSymbols ? Asm.createTempSymbol(Prefix) : nullptr;
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NumBytes += Str.size() + 1;
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}
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return *I.first;
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}
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DwarfStringPool::EntryRef DwarfStringPool::getEntry(AsmPrinter &Asm,
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StringRef Str) {
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auto &MapEntry = getEntryImpl(Asm, Str);
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return EntryRef(MapEntry, false);
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}
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DwarfStringPool::EntryRef DwarfStringPool::getIndexedEntry(AsmPrinter &Asm,
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StringRef Str) {
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auto &MapEntry = getEntryImpl(Asm, Str);
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if (!MapEntry.getValue().isIndexed())
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MapEntry.getValue().Index = NumIndexedStrings++;
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return EntryRef(MapEntry, true);
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}
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void DwarfStringPool::emitStringOffsetsTableHeader(AsmPrinter &Asm,
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MCSection *Section,
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MCSymbol *StartSym) {
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if (getNumIndexedStrings() == 0)
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return;
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Asm.OutStreamer->SwitchSection(Section);
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unsigned EntrySize = Asm.getDwarfOffsetByteSize();
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// We are emitting the header for a contribution to the string offsets
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// table. The header consists of an entry with the contribution's
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// size (not including the size of the length field), the DWARF version and
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// 2 bytes of padding.
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Asm.emitDwarfUnitLength(getNumIndexedStrings() * EntrySize + 4,
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"Length of String Offsets Set");
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Asm.emitInt16(Asm.getDwarfVersion());
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Asm.emitInt16(0);
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// Define the symbol that marks the start of the contribution. It is
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// referenced by most unit headers via DW_AT_str_offsets_base.
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// Split units do not use the attribute.
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if (StartSym)
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Asm.OutStreamer->emitLabel(StartSym);
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}
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void DwarfStringPool::emit(AsmPrinter &Asm, MCSection *StrSection,
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MCSection *OffsetSection, bool UseRelativeOffsets) {
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if (Pool.empty())
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return;
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// Start the dwarf str section.
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Asm.OutStreamer->SwitchSection(StrSection);
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// Get all of the string pool entries and sort them by their offset.
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SmallVector<const StringMapEntry<EntryTy> *, 64> Entries;
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Entries.reserve(Pool.size());
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for (const auto &E : Pool)
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Entries.push_back(&E);
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llvm::sort(Entries, [](const StringMapEntry<EntryTy> *A,
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const StringMapEntry<EntryTy> *B) {
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return A->getValue().Offset < B->getValue().Offset;
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});
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for (const auto &Entry : Entries) {
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assert(ShouldCreateSymbols == static_cast<bool>(Entry->getValue().Symbol) &&
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"Mismatch between setting and entry");
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// Emit a label for reference from debug information entries.
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if (ShouldCreateSymbols)
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Asm.OutStreamer->emitLabel(Entry->getValue().Symbol);
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// Emit the string itself with a terminating null byte.
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Asm.OutStreamer->AddComment("string offset=" +
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Twine(Entry->getValue().Offset));
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Asm.OutStreamer->emitBytes(
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StringRef(Entry->getKeyData(), Entry->getKeyLength() + 1));
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}
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// If we've got an offset section go ahead and emit that now as well.
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if (OffsetSection) {
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// Now only take the indexed entries and put them in an array by their ID so
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// we can emit them in order.
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Entries.resize(NumIndexedStrings);
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for (const auto &Entry : Pool) {
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if (Entry.getValue().isIndexed())
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Entries[Entry.getValue().Index] = &Entry;
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}
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Asm.OutStreamer->SwitchSection(OffsetSection);
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unsigned size = Asm.getDwarfOffsetByteSize();
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for (const auto &Entry : Entries)
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if (UseRelativeOffsets)
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Asm.emitDwarfStringOffset(Entry->getValue());
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else
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Asm.OutStreamer->emitIntValue(Entry->getValue().Offset, size);
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}
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}
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