[Bug tree-optimization/84552] [6/7/8 Regression] Compile time hog w/ -O2 -floop-nest-optimize -fno-tree-copy-prop -fno-tree-fre -fno-tree-loop-ivcanon

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84552

--- Comment #4 from Richard Biener  ---
Author: rguenth
Date: Thu Mar  8 14:41:39 2018
New Revision: 258365

URL: https://gcc.gnu.org/viewcvs?rev=258365=gcc=rev
Log:
2018-03-08  Richard Biener  

PR middle-end/84552
* tree-scalar-evolution.c: Include tree-into-ssa.h.
(follow_copies_to_constant): Do not follow SSA names registered
for update.

* gcc.dg/graphite/pr84552.c: New testcase.

Added:
trunk/gcc/testsuite/gcc.dg/graphite/pr84552.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-scalar-evolution.c

[Bug tree-optimization/84552] [6/7/8 Regression] Compile time hog w/ -O2 -floop-nest-optimize -fno-tree-copy-prop -fno-tree-fre -fno-tree-loop-ivcanon

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84552

Richard Biener  changed:

   What|Removed |Added

   Priority|P4  |P2
   Target Milestone|8.0 |6.5
Summary|[8 Regression] Compile time |[6/7/8 Regression] Compile
   |hog w/ -O2  |time hog w/ -O2
   |-floop-nest-optimize|-floop-nest-optimize
   |-fno-tree-copy-prop |-fno-tree-copy-prop
   |-fno-tree-fre   |-fno-tree-fre
   |-fno-tree-loop-ivcanon  |-fno-tree-loop-ivcanon

--- Comment #3 from Richard Biener  ---
So this is really a latent issue and not dependent on -floop-nest-optimize.  It
materializes during unrolling where we perform SCEV analysis on not up-to-date
SSA form when analyzing.