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	Stop creating symbols we don't need in `DwarfStringPool`. The consumers only call `DwarfStringPoolEntryRef::getSymbol()` when DWARF is relocatable, so this just stops creating the unused symbols when it's not. This drops memory usage from 851 MB to 845 MB, around 0.7%. (I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`; see r236629 for details.) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238122 91177308-0d34-0410-b5e6-96231b3b80d8
		
			
				
	
	
		
			75 lines
		
	
	
		
			2.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			75 lines
		
	
	
		
			2.6 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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| 
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| #include "DwarfStringPool.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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| 
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| using namespace llvm;
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| 
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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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| 
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| DwarfStringPool::EntryRef DwarfStringPool::getEntry(AsmPrinter &Asm,
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|                                                     StringRef Str) {
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|   auto I = Pool.insert(std::make_pair(Str, EntryTy()));
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|   if (I.second) {
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|     auto &Entry = I.first->second;
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|     Entry.Index = Pool.size() - 1;
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|     Entry.Offset = NumBytes;
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|     Entry.Symbol = ShouldCreateSymbols ? Asm.createTempSymbol(Prefix) : nullptr;
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| 
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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 EntryRef(*I.first);
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| }
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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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| 
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|   // Start the dwarf str section.
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|   Asm.OutStreamer->SwitchSection(StrSection);
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| 
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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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| 
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|   for (const auto &E : Pool)
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|     Entries[E.getValue().Index] = &E;
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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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| 
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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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| 
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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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| 
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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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