[Bug tree-optimization/79224] New: [7 Regression] Large C-Ray slowdown

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79224

            Bug ID: 79224
           Summary: [7 Regression] Large C-Ray slowdown
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
                CC: hubicka at gcc dot gnu.org
  Target Milestone: ---
            Target: x86_64-*-*

http://gcc.opensuse.org/c++bench-czerny/c-ray/ shows regressions at revision
ranges r239336-r239387 and r243991-r243996 (on x86_64, -O3 -ffast-math
-funroll-loops -march=core-avx2)

And it was good again for a short time, improving between r244241:244289
and regressing again r244382:244454.  The former adjusts PRED_CALL the latter
has the partial DSE adjustments.

See also PR77468 where I split this out from or its dup, PR68664