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Re: [PATCH][RFA] [PR rtl-optimization/64317] Enhance postreload-gcse.c to eliminate more redundant loads
- From: Jeff Law <law at redhat dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Sat, 21 Mar 2015 01:47:10 -0600
- Subject: Re: [PATCH][RFA] [PR rtl-optimization/64317] Enhance postreload-gcse.c to eliminate more redundant loads
- Authentication-results: sourceware.org; auth=none
- References: <5500B3FC dot 7040303 at redhat dot com> <20150316192736 dot GU1746 at tucnak dot redhat dot com>
On 03/16/2015 01:27 PM, Jakub Jelinek wrote:
What effect does the patch have on compile time on say x86_64 or ppc64?
I bootstrapped x86_64 trunk then timed compiling 640 .i/.ii files with
-O2. That was repeated 10 times (to get a sense of variability). Each
run took a little over 40 minutes with variability of less than a second
(slowest run compared to fastest run).
I then also gathered data for a smaller set of runs for -O2
-funroll-loops (given the consistency between runs, 10 iterations seemed
like major overkill). Again variability was less than a second.
I then applied the patch and repeated the -O2 and -O2 -funroll-loops
test. The patched compiler was within a second of the unpatched
compiler for both the -O2 and -O2 -funroll-loops tests. Given the
difference was within the noise level of those tests, my conclusion is
the new code makes no measurable difference in compile time performance
for x86_64.
Similar tests are in progress on powerpc64-linux-gnu.
Jeff