[Patch, i386] Turn on -fschedule-insns and -fsched-pressure by default for x86-64

[H.J. Lu]

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.