[llvm-commits] [llvm] r60399 - in /llvm/trunk/lib: Target/README.txt Transforms/Scalar/InstructionCombining.cpp

[Chris Lattner]

On Dec 2, 2008, at 12:30 AM, Duncan Sands wrote:

>>> why isn't this valid if X isn't a constant?
>>
>> It is valid, but if X is a constant, "-X/C" should and does already
>> constant fold.
>
> But only if C is a constant too, right?

If C isn't a constant, you wouldn't want to do this xform - it isn't  
profitable.

-Chris