[llvm-commits] [llvm] r122330 - in /llvm/trunk: include/llvm/Analysis/InstructionSimplify.h lib/Analysis/InstructionSimplify.cpp lib/Transforms/InstCombine/InstCombineMulDivRem.cpp

[Frits van Bommel]

On Tue, Dec 21, 2010 at 3:00 PM, Duncan Sands <baldrick at free.fr> wrote:
> +  /// i1 add -> xor.
> +  if (!MaxRecurse && Op0->getType()->isIntegerTy(1))
> +    return SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1);
> +

Since !MaxRecurse is true, the MaxRecurse-1 argument will overflow to ~0U.
This will also return null if the xor doesn't simplify even though
some later transformation might still work if it stays an 'add'.
So shouldn't this be something more like
  /// i1 add -> xor.
  if (MaxRecurse && Op0->getType()->isIntegerTy(1))
    if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
      return V;
?
(Note the missing '!')

Same goes for the 'i1 sub -> xor' and 'i1 mul -> and' transforms.