https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80293
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-04-03
CC| |alan.lawrence.arm at gmail dot
com
| |, jakub at gcc dot gnu.org,
| |jamborm at gcc dot gnu.org,
| |ktkachov at gcc dot gnu.org
Target Milestone|--- |6.4
Summary|g++ 5.4 -> 6.1 regression: |[6/7 Regression]
|unnecessary code at -O2 |unnecessary code at -O2
|(-O1 is fine) |(-O1 is fine)
Ever confirmed|0 |1
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r227901, the complete scalarization is not really helpful here,
and unfortunately gimple-ssa-store-merging.c only merges now adjacent constant
stores, not adjacent loads followed by adjacent stores of the loaded values to
undo the damage.
Not sure what would be easier here, if some heuristics during SRA whether the
scalarization is helpful or not, or improving gimple-ssa-store-merging.c.
