[Bug tree-optimization/106809] [12 regression] large bison grammars compilation got a lot slower, mainly due to -Wuninitialized
cvs-commit at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Fri Sep 9 09:49:55 GMT 2022
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106809
--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:
https://gcc.gnu.org/g:e08dd36f90e74cd5be615b1ca82a38896434d48c
commit r12-8751-ge08dd36f90e74cd5be615b1ca82a38896434d48c
Author: Richard Biener <rguenther@suse.de>
Date: Fri Sep 2 13:36:13 2022 +0200
tree-optimization/106809 - compile time hog in VN
The dominated_by_p_w_unex function is prone to high compile time.
With GCC 12 we introduced a VN run for uninit diagnostics which now
runs into a degenerate case with bison generated code. Fortunately
this case is easy to fix with a simple extra check - a more
general fix needs more work.
PR tree-optimization/106809
* tree-ssa-sccvn.cc (dominaged_by_p_w_unex): Check we have
more than one successor before doing extra work.
* gcc.dg/torture/pr106809.c: New testcase.
(cherry picked from commit be1b42de9c151d46c89f9a8f82d4c5839a19ea94)
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