------- Comment #3 from ubizjak at gmail dot com 2007-06-26 19:43 -------
(In reply to comment #0)
> gfortran seemingly generates an significatly inferior internal TREE
> representation than g95 as for Polyhedron's induct.f90 gfortran is 18% slower
> than g95, which is based on GCC 4.0.3. (Compared with other compilers the
> difference is even larger.)
> If one looks at -ftree-vectorizer-verbose, GCC 4.3 is able to vectorize 3
> loops
> with gfortran whereas GCC 4.0 vectorizes 0 loops with g95.
The problem is in -ftree-vectorize:
gfortran -march=core2 -ffast-math -funroll-loops -ftree-loop-linear
-ftree-vectorize -msse3 -O3 pr32084.f90
time ./a.out
real 0m2.941s
user 0m2.940s
sys 0m0.004s
gfortran -march=core2 -ffast-math -funroll-loops -ftree-loop-linear -msse3 -O3
pr32084.f90
time ./a.out
real 0m1.574s
user 0m1.572s
sys 0m0.004s
The testcase runs 47% faster without -ftree-vectorize.
gcc -v
Target: x86_64-unknown-linux-gnu
...
gcc version 4.3.0 20070622 (experimental)
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 CPU X6800 @ 2.93GHz
stepping : 5
cpu MHz : 2933.435
cache size : 4096 KB
This is marked a "tree-optimization" bug because we have no "vectorizer"
component to choose from.
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ubizjak at gmail dot com
Status|UNCONFIRMED |NEW
Component|fortran |tree-optimization
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2007-06-26 19:43:36
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32084
