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888059ed2c
Change `DwarfStringPool` to calculate byte offsets on-the-fly, and update `DwarfUnit::getLocalString()` to use a `DIEInteger` instead of a `DIEDelta` when Dwarf doesn't use relocations (i.e., Mach-O). This eliminates another call to `EmitLabelDifference()`, and drops memory usage from 865 MB down to 861 MB, around 0.5%. (I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`; see r236629 for details.) llvm-svn: 238114
63 lines
2.0 KiB
C++
63 lines
2.0 KiB
C++
//===-- llvm/CodeGen/DwarfStringPool.cpp - Dwarf Debug Framework ----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "DwarfStringPool.h"
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#include "llvm/MC/MCStreamer.h"
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using namespace llvm;
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DwarfStringPool::EntryTy &DwarfStringPool::getEntry(AsmPrinter &Asm,
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StringRef Str) {
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auto &Entry = Pool[Str];
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if (!Entry.Symbol) {
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Entry.Index = Pool.size() - 1;
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Entry.Offset = NumBytes;
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Entry.Symbol = Asm.createTempSymbol(Prefix);
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NumBytes += Str.size() + 1;
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assert(NumBytes > Entry.Offset && "Unexpected overflow");
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}
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return Entry;
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}
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void DwarfStringPool::emit(AsmPrinter &Asm, MCSection *StrSection,
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MCSection *OffsetSection) {
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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 put them in an array by their ID so
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// we can sort them.
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SmallVector<const StringMapEntry<EntryTy> *, 64> Entries(Pool.size());
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for (const auto &E : Pool)
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Entries[E.getValue().Index] = &E;
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for (const auto &Entry : Entries) {
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// Emit a label for reference from debug information entries.
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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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Asm.OutStreamer->SwitchSection(OffsetSection);
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unsigned size = 4; // FIXME: DWARF64 is 8.
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for (const auto &Entry : Entries)
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Asm.OutStreamer->EmitIntValue(Entry->getValue().Offset, size);
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}
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}
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