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Re: [RFC 5/5] Always completely replace constant pool entries

From: Jeff Law <law at redhat dot com>
To: Alan Lawrence <alan dot lawrence at arm dot com>, gcc-patches at gcc dot gnu dot org
Cc: rguenther at suse dot de, mjambor at suse dot cz
Date: Tue, 25 Aug 2015 13:54:16 -0600
Subject: Re: [RFC 5/5] Always completely replace constant pool entries
Authentication-results: sourceware.org; auth=none
References: <1440500777-25966-1-git-send-email-alan dot lawrence at arm dot com> <1440500777-25966-6-git-send-email-alan dot lawrence at arm dot com>

On 08/25/2015 05:06 AM, Alan Lawrence wrote:

I used this as a means of better-testing the previous changes, as it exercises
the constant replacement code a whole lot more. Indeed, quite a few tests are
now optimized away to nothing on AArch64...

Always pulling in constants, is almost certainly not what we want, but we may
nonetheless want something more aggressive than the usual --param, e.g. for the
ssa-dom-cse-2.c test. Thoughts welcomed?

I'm of the opinion that we have too many knobs already. So I'd perhapsask whether or not this option is likely to be useful to end users?

As for the patch itself, any thoughts on reasonable heuristics for whento pull in the constants? Clearly we don't want the patch as-is, butare there cases we can identify when we want to be more aggressive?


jeff

Follow-Ups:
- Re: [RFC 5/5] Always completely replace constant pool entries
  - From: Richard Biener

References:
- [PATCH 0/5][tree-sra.c] PR/63679 Make SRA replace constant pool loads
  - From: Alan Lawrence
- [RFC 5/5] Always completely replace constant pool entries
  - From: Alan Lawrence

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