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Re: [PATCH] Introduce TV_INITIALIZE_RTL

From: Jeff Law <law at redhat dot com>
To: David Malcolm <dmalcolm at redhat dot com>, gcc-patches at gcc dot gnu dot org
Date: Thu, 14 May 2015 11:46:29 -0600
Subject: Re: [PATCH] Introduce TV_INITIALIZE_RTL
Authentication-results: sourceware.org; auth=none
References: <1431620980-12029-1-git-send-email-dmalcolm at redhat dot com>

On 05/14/2015 10:29 AM, David Malcolm wrote:

Before this patch, jit.dg/test-benchmark.c at optlevel 0, 100 iterations
showed "rest of compilation" as taking a significant chunk of time:

rest of compilation     :   1.53 (64%) usr   0.06 (32%) sys   1.60 (27%) wall    1388 kB ( 6%) ggc

This turned out to be almost entirely spent inside initialize_rtl; adding a
TV_INITIALIZE_RTL for this indicates this cost clearly:

initialize rtl          :   1.46 (61%) usr   0.01 ( 5%) sys   1.42 (24%) wall    1156 kB ( 5%) ggc
rest of compilation     :   0.05 ( 2%) usr   0.00 ( 0%) sys   0.00 ( 0%) wall     232 kB ( 1%) ggc

I'm experimenting with a followup patch to amortize this away by making RTL
initialization a one-time deal, but in the meantime, this patch adds
accounting for it.

OK for trunk? (assuming bootstrap and testing)

gcc/ChangeLog:
	* timevar.def (TV_INITIALIZE_RTL): New.
	* toplev.c (initialize_rtl): Use an auto_timevar to account this
	function's time to TV_INITIALIZE_RTL.

We should done this a long time ago -- initialization/startup items area real issue.


OK.

jeff

References:
- [PATCH] Introduce TV_INITIALIZE_RTL
  - From: David Malcolm

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