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[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
- 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, 08 Mar 2018 11:20:57 +0000
- Subject: [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
- Auto-submitted: auto-generated
- References: <bug-84552-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84552
Richard Biener <rguenth at gcc dot gnu.org> 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 <rguenth at gcc dot gnu.org> ---
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.