[LLVMdev] folding x * 0 = 0

[Chris Lattner]

On Mar 3, 2010, at 1:21 PM, David Greene wrote:

>>> 
>>> We may need something akin to a fence over which no code motion can
>>> occur.
>> 
>> Maybe for signaling NaN, I don't know how those things work.
>> I tend to avoid using any FP code in my code ;)
> 
> Signalling NaN is one case.  I'm sure there are others.

The only other thing I could imagine that it is useful for is for rounding mode control.  IMO rounding mode should be explicitly marked on the instruction as well.

-Chris