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Re: [patch] RFC: Hook for insn costs?
- From: Jeff Law <law at redhat dot com>
- To: Richard Earnshaw <Richard dot Earnshaw at foss dot arm dot com>, Richard Henderson <rth at twiddle dot net>, Richard Biener <richard dot guenther at gmail dot com>, Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: Georg-Johann Lay <avr at gjlay dot de>, GCC Development <gcc at gcc dot gnu dot org>
- Date: Thu, 3 Aug 2017 09:52:46 -0600
- Subject: Re: [patch] RFC: Hook for insn costs?
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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.
> 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.