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[Bug tree-optimization/82604] [8 Regression] SPEC CPU2006 410.bwaves ~50% performance regression with trunk@253679 when ftree-parallelize-loops is used
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 19 Oct 2017 07:12:41 +0000
- Subject: [Bug tree-optimization/82604] [8 Regression] SPEC CPU2006 410.bwaves ~50% performance regression with trunk@253679 when ftree-parallelize-loops is used
- Auto-submitted: auto-generated
- References: <bug-82604-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82604
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
CC| |amker at gcc dot gnu.org,
| |matz at gcc dot gnu.org,
| |rguenth at gcc dot gnu.org
Target Milestone|--- |8.0
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I suppose loop distribution inserted a version copy turning this into a
non-perfect nest for outer loops and thus disabling autopar there.
What probably makes sense is to run autoparallelization earlier or to try
-fparallelize-loops-all (using ISL dependence analysis).
Just guesses of course, autopar isn't one of our most elaborate passes...