[LLVMdev] max/min intrinsics
dan433584 at gmail.com
Mon Dec 17 12:01:58 PST 2012
No; real fmin and fmax are symmetric, and fcmp+select patterns are not
Also, on point  "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.
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 . Would that work ?
>  - 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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