[llvm-commits] [llvm] r92939 - /llvm/trunk/include/llvm/IntrinsicsX86.td

[Chris Lattner]

On Jan 7, 2010, at 1:41 PM, David Greene wrote:

> On Thursday 07 January 2010 15:34, Dan Gohman wrote:
>
>>> Why do we have the scalar intrinsics anyway?  Those operations can  
>>> match
>>> to llvm instructions as well, can't they?
>>
>> Almost, but unfortunately not quite. The problem with the "scalar"
>> intrinsics is that they are still defined to have vector operands.
>> Theoretically the addss intrinsic could be lowered to
>> extractelement+fadd+insertelement. Theoretically it could optimize  
>> down to
>> the same eventual result; in practice, it'll probably take someone  
>> to look
>> at it.
>
> Are the intrinsics defined to preserve the upper portion of the  
> register?
> I've never used them.
>
> If so, ugh.  Who came up with this brilliant stuff?  :-/

Yes unfortunately.

-Chris