40% performance regression SPEC2006/leslie3d on gcc-4_2-branch

[H. J. Lu]

On Mon, Feb 19, 2007 at 03:16:12PM -0800, Mark Mitchell wrote:
> Daniel Berlin wrote:
> 
> >> > > > It looks like your changeset listed bellow makes performance
> >> > > > regression ~40% on SPEC2006/leslie3d. I will try to create minimal
> >> > > > test for this issue this week and update you in any case.
> 
> >> > The price of fixing them in 4.2 was a serious performance drop.
> >>
> >> There's the option of un-fixing them to get back to the state of 4.1
> >> declaring
> >> them fixed in 4.3 earliest.
> 
> I would like to understand a few things:
> 
> 1. What is the overall drop in SPEC scores as a result of this patch?  I
> understand the impact on leslie3d, but what is the overall impact?
> Hopefully, this is an easy question to answer: run SPEC, revert the
> patch, run SPEC again.
> 

We are working on complete data of SPEC CPU 2K/2006 on Core 2 Duo.
It will take about a week. Our earlier, mid Jan., SPEC CPU 2006 shows:

FP performance regressions of the recent GCC 4.2 (revision 120817)
compiler against September GCC 4.2 (revision 116799)
	410.bwaves		-6.3%
	433.milc		-7.0%
	437.leslie3d	-25.4%
	450.soplex		-3.9%
	459.GemsFDTD	-18.3%
	465.tonto		-2.5%
	470.lbm		-4.1%
	481.wrf		-2.7%



H.J.