[llvm] r207118 - Fix memory leak of MCSymbolData in MCAsmStreamer.

[NAKAMURA Takumi]

Thanks! test/MC became fine!

2014-04-24 23:33 GMT+09:00 David Blaikie <dblaikie at gmail.com>:
> Author: dblaikie
> Date: Thu Apr 24 09:33:36 2014
> New Revision: 207118
>
> URL: http://llvm.org/viewvc/llvm-project?rev=207118&view=rev
> Log:
> Fix memory leak of MCSymbolData in MCAsmStreamer.
>
> Leak identified by LSan and reported by Kostya Serebryany.
>
> Let's get a bit experimental here... in theory our minimum compiler
> versions support unordered_map.
>
> Modified:
>     llvm/trunk/lib/MC/MCAsmStreamer.cpp
>
> Modified: llvm/trunk/lib/MC/MCAsmStreamer.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCAsmStreamer.cpp?rev=207118&r1=207117&r2=207118&view=diff
> ==============================================================================
> --- llvm/trunk/lib/MC/MCAsmStreamer.cpp (original)
> +++ llvm/trunk/lib/MC/MCAsmStreamer.cpp Thu Apr 24 09:33:36 2014
> @@ -9,6 +9,7 @@
>
>  #include "llvm/MC/MCStreamer.h"
>  #include "llvm/ADT/SmallString.h"
> +#include "llvm/ADT/STLExtras.h"
>  #include "llvm/ADT/StringExtras.h"
>  #include "llvm/ADT/Twine.h"
>  #include "llvm/MC/MCAsmBackend.h"
> @@ -31,6 +32,7 @@
>  #include "llvm/Support/MathExtras.h"
>  #include "llvm/Support/Path.h"
>  #include <cctype>
> +#include <unordered_map>
>  using namespace llvm;
>
>  namespace {
> @@ -57,7 +59,9 @@ private:
>                         EHPrivateExtern  = 1 << 2 };
>    DenseMap<const MCSymbol*, unsigned> FlagMap;
>
> -  DenseMap<const MCSymbol*, MCSymbolData*> SymbolMap;
> +  // Using std::unordered_map to ensure pointers to MCSymbolData remain valid
> +  // over insertions/removals from the SymbolMap.
> +  std::unordered_map<const MCSymbol*, MCSymbolData> SymbolMap;
>
>    void EmitRegisterName(int64_t Register);
>    void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
> @@ -76,7 +80,6 @@ public:
>      if (InstPrinter && IsVerboseAsm)
>        InstPrinter->setCommentStream(CommentStream);
>    }
> -  ~MCAsmStreamer() {}
>
>    inline void EmitEOL() {
>      // If we don't have any comments, just emit a \n.
> @@ -1470,12 +1473,11 @@ void MCAsmStreamer::FinishImpl() {
>  }
>
>  MCSymbolData &MCAsmStreamer::getOrCreateSymbolData(const MCSymbol *Symbol) {
> -  MCSymbolData *&Entry = SymbolMap[Symbol];
> -
> -  if (!Entry)
> -    Entry = new MCSymbolData(*Symbol, nullptr, 0, nullptr);
> -
> -  return *Entry;
> +  auto Iter = SymbolMap.find(Symbol);
> +  if (Iter == SymbolMap.end())
> +    Iter = SymbolMap.insert(
> +        Iter, std::make_pair(Symbol, MCSymbolData(*Symbol, nullptr, 0)));
> +  return Iter->second;
>  }
>
>  MCStreamer *llvm::createAsmStreamer(MCContext &Context,
>
>
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