[LLVMdev] "equivalent" .ll files diverge after optimizations are applied

Chris Lattner clattner at apple.com
Tue Aug 31 14:20:27 PDT 2010

On Aug 31, 2010, at 1:29 PM, Dale Johannesen wrote:

> On Aug 31, 2010, at 1:21 PMPDT, Argyrios Kyrtzidis wrote:
>> Just to be clear, are you saying that the fact that, after using llc  
>> on the second IR, the produced asm is using MM registers, indicates  
>> a bug ?
> Yes.  It's not immediately obvious whether it's in the opt or llc,  
> though.
> Chris was doing work involving <2 x float> and may know about this.

I did.  <2 x float> doesn't use MMX, but <2 x int> probably does.  It is possible that hte optimizer is turning <2 x float> operations into <2 x int> ones or something...


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