[llvm] r337596 - [Demangler] Correctly factor in assignment when allocating.

Matt Morehouse via llvm-commits llvm-commits at lists.llvm.org
Mon Jul 23 09:37:31 PDT 2018


This is causing memory leaks:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/21207.
Please take a look.

==38753==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 1776 byte(s) in 74 object(s) allocated from:
    #0 0x50cfa8 in operator new(unsigned long)
/b/sanitizer-x86_64-linux-fast/build/llvm/projects/compiler-rt/lib/asan/asan_new_delete.cc:92
    #1 0x51452e in ArenaAllocator
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/Demangle/MicrosoftDemangle.cpp:39:27
    #2 0x51452e in Demangler
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/Demangle/MicrosoftDemangle.cpp:594
    #3 0x51452e in llvm::microsoftDemangle(char const*, char*,
unsigned long*, int*)
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/Demangle/MicrosoftDemangle.cpp:1535
    #4 0x5128c0 in demangle(std::__1::basic_string<char,
std::__1::char_traits<char>, std::__1::allocator<char> > const&)
/b/sanitizer-x86_64-linux-fast/build/llvm/tools/llvm-undname/llvm-undname.cpp:34:21
    #5 0x5122b9 in main
/b/sanitizer-x86_64-linux-fast/build/llvm/tools/llvm-undname/llvm-undname.cpp:67:7
    #6 0x7f9756c832e0 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x202e0)

SUMMARY: AddressSanitizer: 1776 byte(s) leaked in 74 allocation(s).




On Fri, Jul 20, 2018 at 11:40 AM Zachary Turner via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: zturner
> Date: Fri Jul 20 11:35:06 2018
> New Revision: 337596
>
> URL: http://llvm.org/viewvc/llvm-project?rev=337596&view=rev
> Log:
> [Demangler] Correctly factor in assignment when allocating.
>
> Incidentally all allocations that we currently perform were
> properly aligned, but this was only an accident.
>
> Thanks to Erik Pilkington for catching this.
>
> Modified:
>     llvm/trunk/lib/Demangle/MicrosoftDemangle.cpp
>
> Modified: llvm/trunk/lib/Demangle/MicrosoftDemangle.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Demangle/MicrosoftDemangle.cpp?rev=337596&r1=337595&r2=337596&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Demangle/MicrosoftDemangle.cpp (original)
> +++ llvm/trunk/lib/Demangle/MicrosoftDemangle.cpp Fri Jul 20 11:35:06 2018
> @@ -46,21 +46,28 @@ public:
>      }
>    }
>
> -  void *alloc(size_t Size) {
> +  template <typename T, typename... Args> T *alloc(Args &&...
> ConstructorArgs) {
> +
> +    size_t Size = sizeof(T);
>      assert(Size < Unit);
>      assert(Head && Head->Buf);
>
> -    uint8_t *P = Head->Buf + Head->Used;
> -    Head->Used += Size;
> +    size_t P = (size_t)Head->Buf + Head->Used;
> +    uintptr_t AlignedP =
> +        (((size_t)P + alignof(T) - 1) & ~(size_t)(alignof(T) - 1));
> +    uint8_t *PP = (uint8_t *)AlignedP;
> +    size_t Adjustment = AlignedP - P;
> +
> +    Head->Used += Size + Adjustment;
>      if (Head->Used < Unit)
> -      return P;
> +      return new (PP) T(std::forward<Args>(ConstructorArgs)...);
>
>      AllocatorNode *NewHead = new AllocatorNode;
>      NewHead->Buf = new uint8_t[ArenaAllocator::Unit];
>      NewHead->Next = Head;
>      Head = NewHead;
>      NewHead->Used = Size;
> -    return NewHead->Buf;
> +    return new (NewHead->Buf) T(std::forward<Args>(ConstructorArgs)...);
>    }
>
>  private:
> @@ -84,8 +91,6 @@ static void outputSpaceIfNecessary(Outpu
>      OS << " ";
>  }
>
> -void *operator new(size_t Size, ArenaAllocator &A) { return
> A.alloc(Size); }
> -
>  // Storage classes
>  enum Qualifiers : uint8_t {
>    Q_None = 0,
> @@ -374,7 +379,7 @@ static void outputName(OutputStream &OS,
>  namespace {
>
>  Type *Type::clone(ArenaAllocator &Arena) const {
> -  return new (Arena) Type(*this);
> +  return Arena.alloc<Type>(*this);
>  }
>
>  // Write the "first half" of a given type.
> @@ -471,7 +476,7 @@ void Type::outputPre(OutputStream &OS) {
>  void Type::outputPost(OutputStream &OS) {}
>
>  Type *PointerType::clone(ArenaAllocator &Arena) const {
> -  return new (Arena) PointerType(*this);
> +  return Arena.alloc<PointerType>(*this);
>  }
>
>  void PointerType::outputPre(OutputStream &OS) {
> @@ -509,7 +514,7 @@ void PointerType::outputPost(OutputStrea
>  }
>
>  Type *FunctionType::clone(ArenaAllocator &Arena) const {
> -  return new (Arena) FunctionType(*this);
> +  return Arena.alloc<FunctionType>(*this);
>  }
>
>  void FunctionType::outputPre(OutputStream &OS) {
> @@ -536,7 +541,7 @@ void FunctionType::outputPost(OutputStre
>  }
>
>  Type *UdtType::clone(ArenaAllocator &Arena) const {
> -  return new (Arena) UdtType(*this);
> +  return Arena.alloc<UdtType>(*this);
>  }
>
>  void UdtType::outputPre(OutputStream &OS) {
> @@ -561,7 +566,7 @@ void UdtType::outputPre(OutputStream &OS
>  }
>
>  Type *ArrayType::clone(ArenaAllocator &Arena) const {
> -  return new (Arena) ArrayType(*this);
> +  return Arena.alloc<ArrayType>(*this);
>  }
>
>  void ArrayType::outputPre(OutputStream &OS) {
> @@ -659,9 +664,9 @@ private:
>  void Demangler::parse() {
>    // MSVC-style mangled symbols must start with '?'.
>    if (!MangledName.consumeFront("?")) {
> -    SymbolName = new (Arena) Name;
> +    SymbolName = Arena.alloc<Name>();
>      SymbolName->Str = MangledName;
> -    SymbolType = new (Arena) Type;
> +    SymbolType = Arena.alloc<Type>();
>      SymbolType->Prim = PrimTy::Unknown;
>    }
>
> @@ -832,7 +837,7 @@ Name *Demangler::demangleName() {
>    Name *Head = nullptr;
>
>    while (!MangledName.consumeFront("@")) {
> -    Name *Elem = new (Arena) Name;
> +    Name *Elem = Arena.alloc<Name>();
>
>      assert(!Error);
>      demangleNamePiece(*Elem, Head == nullptr);
> @@ -1239,7 +1244,7 @@ ReferenceKind Demangler::demangleReferen
>  }
>
>  Type *Demangler::demangleFunctionEncoding() {
> -  FunctionType *FTy = new (Arena) FunctionType;
> +  FunctionType *FTy = Arena.alloc<FunctionType>();
>
>    FTy->Prim = PrimTy::Function;
>    FTy->FunctionClass = (FuncClass)demangleFunctionClass();
> @@ -1265,7 +1270,7 @@ Type *Demangler::demangleFunctionEncodin
>
>  // Reads a primitive type.
>  Type *Demangler::demangleBasicType() {
> -  Type *Ty = new (Arena) Type;
> +  Type *Ty = Arena.alloc<Type>();
>
>    switch (MangledName.popFront()) {
>    case 'X':
> @@ -1335,7 +1340,7 @@ Type *Demangler::demangleBasicType() {
>  }
>
>  UdtType *Demangler::demangleClassType() {
> -  UdtType *UTy = new (Arena) UdtType;
> +  UdtType *UTy = Arena.alloc<UdtType>();
>
>    switch (MangledName.popFront()) {
>    case 'T':
> @@ -1365,7 +1370,7 @@ UdtType *Demangler::demangleClassType()
>  // <pointer-type> ::= E? <pointer-cvr-qualifiers> <ext-qualifiers> <type>
>  //                       # the E is required for 64-bit non-static
> pointers
>  PointerType *Demangler::demanglePointerType() {
> -  PointerType *Pointer = new (Arena) PointerType;
> +  PointerType *Pointer = Arena.alloc<PointerType>();
>
>    Pointer->Quals = Q_None;
>    switch (MangledName.popFront()) {
> @@ -1392,7 +1397,7 @@ PointerType *Demangler::demanglePointerT
>    }
>
>    if (MangledName.consumeFront("6")) {
> -    FunctionType *FTy = new (Arena) FunctionType;
> +    FunctionType *FTy = Arena.alloc<FunctionType>();
>      FTy->Prim = PrimTy::Function;
>      FTy->CallConvention = demangleCallingConvention();
>
> @@ -1435,12 +1440,12 @@ ArrayType *Demangler::demangleArrayType(
>      return nullptr;
>    }
>
> -  ArrayType *ATy = new (Arena) ArrayType;
> +  ArrayType *ATy = Arena.alloc<ArrayType>();
>    ArrayType *Dim = ATy;
>    for (int I = 0; I < Dimension; ++I) {
>      Dim->Prim = PrimTy::Array;
>      Dim->ArrayDimension = demangleNumber();
> -    Dim->NextDimension = new (Arena) ArrayType;
> +    Dim->NextDimension = Arena.alloc<ArrayType>();
>      Dim = Dim->NextDimension;
>    }
>
> @@ -1476,7 +1481,7 @@ ParamList Demangler::demangleParameterLi
>        }
>        MangledName = MangledName.dropFront();
>
> -      *Current = new (Arena) ParamList;
> +      *Current = Arena.alloc<ParamList>();
>        (*Current)->Current = BackRef[N]->clone(Arena);
>        Current = &(*Current)->Next;
>        continue;
> @@ -1484,7 +1489,7 @@ ParamList Demangler::demangleParameterLi
>
>      size_t ArrayDimension = MangledName.size();
>
> -    *Current = new (Arena) ParamList;
> +    *Current = Arena.alloc<ParamList>();
>      (*Current)->Current = demangleType(QualifierMangleMode::Drop);
>
>      // Single-letter types are ignored for backreferences because
>
>
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