[llvm-commits] [llvm-gcc-4.2] r67690 - in /llvm-gcc-4.2/trunk/gcc: llvm-convert.cpp llvm-internal.h

[Evan Cheng]

On Mar 25, 2009, at 10:13 AM, Duncan Sands wrote:

> Hi Evan,
>
>> +  if (BitCastInst *BC = dyn_cast<BitCastInst>(Size))
>> +    Size = BC->getOperand(0);
>
> why would this ever be a bitcast?

This code in llvm-convert.cpp:

     Value *RHS = Emit(rhs, 0);
     const Type *LHSTy = ConvertType(TREE_TYPE(lhs));
     // The value may need to be replaced later if this temporary is  
multiply
     // defined - ensure it can be uniquely identified by not folding  
the cast.
     Instruction::CastOps opc = CastInst::getCastOpcode(RHS, RHSSigned,
                                                      LHSTy, LHSSigned);
     CastInst *Cast = CastInst::Create(opc, RHS, LHSTy, RHS- 
 >getNameStart());

This emits a noop bitcast:
%1 = bitcast i32 -1 to i32

I'll fix the rest.

Evan

>
>> +  ConstantInt *LenCI = dyn_cast<ConstantInt>(Len);
>> +  if (!LenCI)
>> +    return false;
>
> If Size can be a bitcast, why not Len?
>
>> +  if (LenCI->getZExtValue() >= SizeCI->getZExtValue()) {
>
> This will blow up if Len or Size doesn't fit in 64 bits.
> Of course real code will never have such big values, but
> that's no reason ignore this possibility.
>
> Ciao,
>
> Duncan.