[LLVMdev] max/min intrinsics

[Dan Gohman]

No; real fmin and fmax are symmetric, and fcmp+select patterns are not
symmetric.

Also, on point [3] "An SNaN may behave as a QNaN", LLVM doesn't
correctly implement SNaN anyway, so there's no need to clutter up the
rules with SNaN exceptions. When (if?) someone ever implements SNaN,
they'll probably need to introduce a new operator flag to allow passes
to ignore it (nsnan?), and then fmin/fmax can use that.

Dan

On Mon, Dec 17, 2012 at 11:20 AM, Nadav Rotem <nrotem at apple.com> wrote:
> Maybe we can have two versions of the intrinsic function, "ordered" and "unordered", just like fcmp has [1].  Would that work ?
>
> [1] - http://llvm.org/docs/LangRef.html#fcmp-instruction
>
>
>
> On Dec 17, 2012, at 11:14 AM, "Schoedel, Kevin P" <kevin.p.schoedel at intel.com> wrote:
>
>> At Monday, December 17, 2012 2:05 PM, Nadav Rotem [mailto:nrotem at apple.com]  wrote:
>>> This part worries me.  The new min/max intrinsics will only be useful if we could pattern match cmp/select into them.
>>
>> Yes, that's the obvious alternative. I don't think we have any strong opinion either way, and fcmp/select is certainly easier to implement.
>>
>> --
>> Kevin Schoedel, Software Developer, Intel of Canada
>> <kevin.p.schoedel at intel.com>      +1 (519) 772-2580
>>
>>
>>
>>
>
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