[patch] RFC: Hook for insn costs?

[Jeff Law]

On 08/02/2017 01:34 PM, Richard Earnshaw wrote:
> On 26/07/17 18:54, Jeff Law wrote:
>> On 07/17/2017 02:35 PM, Richard Henderson wrote:
>>> On 07/17/2017 12:20 AM, Richard Biener wrote:
>>>> On Sun, Jul 16, 2017 at 12:51 AM, Segher Boessenkool
>>>>> Now what should it take as input?  An rtx_insn, or just the pattern
>>>>> (as insn_rtx_cost does)?
>>>>
>>>> Is there any useful info on the other operands of an rtx_insn?  If not
>>>> then passing in the pattern (a rtx) might be somewhat more flexible.
>>>> Of course it's then way easier to confuse rtx_cost and insn_cost ...
>>>
>>> A lot of really complex by-hand pattern matching goes away if you know
>>> the instruction is valid, and you can look up an insn attribute.  That
>>> suggests passing the insn and not the PATTERN.
>> Good point.  In fact, it opens the possibility that costing could be
>> attached to the insn itself as just another attribute if it made sense
>> for the target to describe costing in that manner.
>>
>> Jeff
>>
> 
> I'm not sure if that's a good or a bad thing. 
I haven't really though much about it and I certainly wouldn't push for
it as a direction without further investigation.  It's just one thing
that could be possible if we though it made sense.

jeff