https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97856
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Version|unknown |11.0
Component|tree-optimization |rtl-optimization
Ever confirmed|0 |1
CC| |hubicka at gcc dot gnu.org
Status|UNCONFIRMED |NEW
Last reconfirmed| |2020-11-17
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. basic-block reordering decides to duplicate the block:
Redirecting fallthru edge 7->8 to 9
Duplicated bb 8 (created bb 9)
Final order:
2 3 4 8 5 6 7 9
Reordered sequence:
2 bb 2
3 bb 3
4 bb 4
5 bb 8
6 bb 5
7 bb 6
8 bb 7
9 duplicate of 8
since we decide to put the default: handling on the fallthru edge of the
condition chain we duplicate it to the tail as well. IIRC expansion
always does it this way and BB reorder simply avoids one jump. With -Os
we flip the last jump and avoid the duplication.
