https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88763
Bug ID: 88763
Summary: Better Output for Loop Unswitching
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: marius.messerschmidt at googlemail dot com
Target Milestone: ---
I work on a project where we heavily rely on the loop-unswitching feature of
GCC (-funswitch-loops). I started working with the log generated by
-fdump-tree-unswitch.
I started noticing, that the output of the option is very limited. It does only
report a few cases where the optimizer could not unswitch a loop. But in the
source file (gcc/tree-ssa-loop-unswitch.c) there are quite a lot more checks
that lead to a not unswitched loop. Especially the "not invariant" case could
be realy helpfull in the logs.
I tried to implement further warnings, but I do not fully understand every case
in the file, so I am asking someone with better understanding of the internals
of GCC to either fix the bug or explain a few things for me.
Many thanks in Advance :)
