This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: [PATCH, PR target/65103, 2/3] Propagate address constants into loops for i386

From: Jeff Law <law at redhat dot com>
To: Ilya Enkovich <enkovich dot gnu at gmail dot com>, gcc-patches at gcc dot gnu dot org, rdsandiford at googlemail dot com
Date: Mon, 13 Apr 2015 23:22:29 -0600
Subject: Re: [PATCH, PR target/65103, 2/3] Propagate address constants into loops for i386
Authentication-results: sourceware.org; auth=none
References: <20150310150027 dot GC27860 at msticlxl57 dot ims dot intel dot com> <8761a22ecm dot fsf at googlemail dot com>

On 03/15/2015 02:30 PM, Richard Sandiford wrote:

Ilya Enkovich <enkovich.gnu@gmail.com> writes:

This patch allows propagation of loop invariants for i386 if propagated
value is a constant to be used in address operand.  Bootstrapped and
tested on x86_64-unknown-linux-gnu.  OK for trunk or stage 1?


Is it necessary for this to be a target hook?  The concept doesn't seem
particularly target-specific.  We should only propagate into the address
if the new cost is no greater than the old cost, but if the address
meets that condition and if propagating at this point in the pipeline is
a win on x86, then wouldn't it be a win for other targets too?

I agree with Richard here. I can't see a strong reason why this shouldbe a target hook.

Perhaps part of the issue here is the address costing metrics may nothave enough context to make good decisions. In which case what contextdo they need?


Jeff

Follow-Ups:
- Re: [PATCH, PR target/65103, 2/3] Propagate address constants into loops for i386
  - From: Ilya Enkovich

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]