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Re: [PATCH Atom][PR middle-end/44382] Tree reassociation improvement
- From: "William J. Schmidt" <wschmidt at linux dot vnet dot ibm dot com>
- To: ÐÐÑÑ ÐÐÐÐÐ ÐÑ <enkovich dot gnu at gmail dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Wed, 13 Jul 2011 07:57:15 -0500
- Subject: Re: [PATCH Atom][PR middle-end/44382] Tree reassociation improvement
- References: <1310489429.5266.25.camel@oc2474580526.ibm.com>
On Tue, 2011-07-12 at 11:50 -0500, William J. Schmidt wrote:
> Ilya, thanks for posting this! This patch is useful also on powerpc64.
> Applying it solved a performance degradation with bwaves due to loss of
> reassociation somewhere between 4.5 and 4.6 (still tracking it down).
> When we apply -ftree-reassoc-width=2 to bwaves, the more optimal code
> generation returns.
On further investigation, this is improving the code generation but not
reverting all of the performance loss. We'll open a bug on this one
once we have it narrowed down a little further.
Bill
>
> Bill
>