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[Bug tree-optimization/30032] sqrt(CGAMMA*PRES[j]/DENS[j]) much slower than compiting compiler
- From: "burnus at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 30 Nov 2006 18:54:14 -0000
- Subject: [Bug tree-optimization/30032] sqrt(CGAMMA*PRES[j]/DENS[j]) much slower than compiting compiler
- References: <bug-30032-13404@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from burnus at gcc dot gnu dot org 2006-11-30 18:54 -------
Created an attachment (id=12717)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=12717&action=view)
icc -O3 -xW -S of only the function eos()
> but I think what ICC does is only calculates CS[1] instead of all of CS[i].
I don't think so. If I use:
for(j = 0; j < NODES; j++) {
CGAMMA = CGAMMA + CS[j];
}
rather than
CGAMMA = CGAMMA + CS[1];
the timings don't change. I also didn't include -ip or -ipo (inter process
analysis). With this change: icc 0m2.324s; gcc 0m7.194s.
> Also you are using VLAs so maybe ICC also converts those VLAs to normal
> arrays. You might also want to add "-mfpmath=sse,387".
This does not really help: gcc 0m7.066s
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30032