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Re: Polyhedron performance regression
- From: FX Coudert <fxcoudert at gmail dot com>
- To: Paul Richard Thomas <paul dot richard dot thomas at gmail dot com>
- Cc: stevenb dot gcc at gmail dot com, richard dot guenther at gmail dot com, paolo dot bonzini at lu dot unisi dot ch, fortran at gcc dot gnu dot org
- Date: Sun, 12 Nov 2006 17:21:51 +0100
- Subject: Re: Polyhedron performance regression
- References: <339c37f20611120416j32a7798ft318d63b604d18a56@mail.gmail.com>
On x86_ia64/FC5 with:
/svn-4.3/bin/gfortran -static -O3 -ffast-math -funroll-loops ac.f90
time ./a.out
revision time
118474 9.77s
118475 12.3s
current 33.0s !
On x86_64-linux "Dual Core AMD Opteron(tm) Processor 265", 1.8 GHz,
with gfortran -static -O2 -funroll-loops -ftree-vectorize ac.f90
118474 21.695
118480 21.710
118485 21.794
118491 21.771
118492 54.635
I'm ashamed that revision 118492 (http://gcc.gnu.org/viewcvs?
view=rev&revision=118492), which introduced this performance
regression, is the MOD/MODULO patch by Paul Thomas and myself.
While with -ffast-math:
rev. 118474 rev. 118492
17.730 55.599 -O2 -funroll-loops ac.f90 -ffast-math
17.776 53.062 -O3 -funroll-loops ac.f90 -ffast-math
25.549 59.131 -O2
17.554 52.921 -O3 -ftree-vectorize -ffast-math -funroll-loops
Still one thing I don't understand is the difference between Paul
results and mine for the fwprop: it looks like it impacted with -O3 -
ftree-vectorize -fno-fast-math.
FX