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Re: Code performance regression between gcc 4.5 and 4.6
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Martin Reinecke <martin at mpa-garching dot mpg dot de>
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 4 Jan 2011 05:48:19 -0800
- Subject: Re: Code performance regression between gcc 4.5 and 4.6
- References: <4D231603.90104@mpa-garching.mpg.de>
On Tue, Jan 4, 2011 at 4:43 AM, Martin Reinecke
<martin@mpa-garching.mpg.de> wrote:
> Hi,
>
> while benchmarking a numerical C library making heavy use of SSE2
> intrinsics, I have noticed a significant (around 10 percent) slowdown
> in the code generated by the current gcc trunk, compared to the one
> produced by the 4.5.1 release.
> It's quite hard to reduce the code to a small test case, but I can easily
> point out the hot code regions where most of the CPU time is spent.
> Do you think I should open a PR for this, or is this kind of performance
> fluctuation to be expected?
>
What compiler flags are you using? On which processors do you
run the library?
--
H.J.