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