[LLVMdev] ICE in LLVM GCC4 Front End

[Chris Lattner]

On Mon, 11 Sep 2006, Bill Wendling wrote:
> I'm far from an expert on this area of the code base, so I'm
> submitting this as a proposed fix:

Patch looks great.  I switched it to use "if (ElTy->isSized())" instead of 
checking to see if it's abstract.  Types like "{ opaque* }" are considered 
abstract (because they contain an opaque type in the type graph) but they 
have a size (in this case, sizeof(pointer)).

Thanks for tracking this down! I've applied the fix.

-Chris


> Index: gcc/llvm-convert.cpp
> ===================================================================
> --- gcc/llvm-convert.cpp        (revision 166)
> +++ gcc/llvm-convert.cpp        (working copy)
> @@ -2202,18 +2202,23 @@
>
>      // Figure out how large the element pointed to is.
>      const Type *ElTy = cast<PointerType>(LHS->getType())-
> >getElementType();
> -    int64_t EltSize = TD.getTypeSize(ElTy);
> +
> +    if (!ElTy->isAbstract()) {
> +      // We can only get the type size (and thus convert to using a
> GEP instr)
> +      // if the type isn't abstract
> +      int64_t EltSize = TD.getTypeSize(ElTy);
>
> -    // If EltSize exactly divides Offset, then we know that we can
> turn this
> -    // into a getelementptr instruction.
> -    int64_t EltOffset = Offset/EltSize;
> -    if (EltOffset*EltSize == Offset) {
> -      // If this is a subtract, we want to step backwards.
> -      if (Opc == Instruction::Sub)
> -        EltOffset = -EltOffset;
> -      Constant *C = ConstantSInt::get(Type::LongTy, EltOffset);
> -      Value *V = new GetElementPtrInst(LHS, C, "tmp", CurBB);
> -      return CastToType(V, TREE_TYPE(exp));
> +      // If EltSize exactly divides Offset, then we know that we can
> turn
> +      // this into a getelementptr instruction.
> +      int64_t EltOffset = Offset/EltSize;
> +      if (EltOffset*EltSize == Offset) {
> +        // If this is a subtract, we want to step backwards.
> +        if (Opc == Instruction::Sub)
> +          EltOffset = -EltOffset;
> +        Constant *C = ConstantSInt::get(Type::LongTy, EltOffset);
> +        Value *V = new GetElementPtrInst(LHS, C, "tmp", CurBB);
> +        return CastToType(V, TREE_TYPE(exp));
> +      }
>      }
>    }
>
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-Chris

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