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Re: [Patch, i386] Turn on -fschedule-insns and -fsched-pressure by default for x86-64
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: "Fang, Changpeng" <Changpeng dot Fang at amd dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, "sebpop at gmail dot com" <sebpop at gmail dot com>, "Yazdani, Reza" <Reza dot Yazdani at amd dot com>
- Date: Mon, 6 Dec 2010 13:18:01 -0800
- Subject: Re: [Patch, i386] Turn on -fschedule-insns and -fsched-pressure by default for x86-64
- References: <D4C76825A6780047854A11E93CDE84D004C17683E8@SAUSEXMBP01.amd.com>
On Mon, Dec 6, 2010 at 12:04 PM, Fang, Changpeng <Changpeng.Fang@amd.com> wrote:
> Hi,
>
> Attached is the patch that proposes to turn on -fschedule-insns and -fsched-pressure by default at
> -O2 or higher (for speed-runs only) for x86-64 systems. ?Enablement of these two flags could improve
> the performance of floating point programs (For CFP2006, 2.29% under -O2, and ?1.34% under -O3).
> There is no apparent performance ?impact on integer programs (as expected).
>
> We have investigated this optimization since 4.5, and it is the time to turn on these two flags to enjoy
> the performance gains.
>
> The patch passed bootstrappings under -O2 and -O3 on ?x86_64-unknown-linux-gnu, and passed
> the gcc regression tests.
>
> Is it OK to commit the patch?
"-fschedule-insns -fsched-pressure" isn't well tested:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46829
Have you run "-fschedule-insns -fsched-pressure" on gcc testsuite?
--
H.J.