[llvm-commits] [llvm] r162131 - /llvm/trunk/lib/CodeGen/StackProtector.cpp

[Duncan Sands]

Hi Bill,

> Implement stack protectors for structures with character arrays in them.
> <rdar://problem/10545247>
>
> Modified:
>      llvm/trunk/lib/CodeGen/StackProtector.cpp
>
> Modified: llvm/trunk/lib/CodeGen/StackProtector.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StackProtector.cpp?rev=162131&r1=162130&r2=162131&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/StackProtector.cpp (original)
> +++ llvm/trunk/lib/CodeGen/StackProtector.cpp Fri Aug 17 15:59:56 2012
> @@ -61,6 +61,11 @@
>       /// check fails.
>       BasicBlock *CreateFailBB();
>
> +    /// ContainsProtectableArray - Check whether the type either is an array or
> +    /// contains an array of sufficient size so that we need stack protectors
> +    /// for it.
> +    bool ContainsProtectableArray(Type *Ty, bool InStruct = false) const;
> +
>       /// RequiresStackProtector - Check whether or not this function needs a
>       /// stack protector based upon the stack protector level.
>       bool RequiresStackProtector() const;
> @@ -100,6 +105,39 @@
>     return InsertStackProtectors();
>   }
>
> +/// ContainsProtectableArray - Check whether the type either is an array or
> +/// contains a char array of sufficient size so that we need stack protectors
> +/// for it.
> +bool StackProtector::ContainsProtectableArray(Type *Ty, bool InStruct) const {
> +  if (!Ty) return false;
> +  if (ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
> +    if (!AT->getElementType()->isIntegerTy(8)) {
> +      const TargetMachine &TM = TLI->getTargetMachine();
> +      Triple Trip(TM.getTargetTriple());
> +
> +      // If we're on a non-Darwin platform or we're inside of a structure, don't
> +      // add stack protectors unless the array is a character array.
> +      if (InStruct || !Trip.isOSDarwin())
> +          return false;

why do you treat Darwin specially here?  Also, why do you care whether there is
an array or not, isn't it only the amount of memory allocated by the alloca that
matters?

Ciao, Duncan.

> +    }
> +
> +    // If an array has more than SSPBufferSize bytes of allocated space, then we
> +    // emit stack protectors.
> +    if (SSPBufferSize <= TLI->getTargetData()->getTypeAllocSize(AT))
> +      return true;
> +  }
> +
> +  const StructType *ST = dyn_cast<StructType>(Ty);
> +  if (!ST) return false;
> +
> +  for (StructType::element_iterator I = ST->element_begin(),
> +         E = ST->element_end(); I != E; ++I)
> +    if (ContainsProtectableArray(*I, true))
> +      return true;
> +
> +  return false;
> +}
> +
>   /// RequiresStackProtector - Check whether or not this function needs a stack
>   /// protector based upon the stack protector level. The heuristic we use is to
>   /// add a guard variable to functions that call alloca, and functions with
> @@ -111,10 +149,6 @@
>     if (!F->hasFnAttr(Attribute::StackProtect))
>       return false;
>
> -  const TargetData *TD = TLI->getTargetData();
> -  const TargetMachine &TM = TLI->getTargetMachine();
> -  Triple Trip(TM.getTargetTriple());
> -
>     for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
>       BasicBlock *BB = I;
>
> @@ -126,17 +160,8 @@
>             // protectors.
>             return true;
>
> -        if (ArrayType *AT = dyn_cast<ArrayType>(AI->getAllocatedType())) {
> -          // If we're on a non-Darwin platform, don't add stack protectors
> -          // unless the array is a character array.
> -          if (!Trip.isOSDarwin() && !AT->getElementType()->isIntegerTy(8))
> -            continue;
> -
> -          // If an array has more than SSPBufferSize bytes of allocated space,
> -          // then we emit stack protectors.
> -          if (SSPBufferSize <= TD->getTypeAllocSize(AT))
> -            return true;
> -        }
> +        if (ContainsProtectableArray(AI->getAllocatedType()))
> +          return true;
>         }
>     }
>
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>