On Tue, Feb 10, 2026 at 10:59:13AM +0100, Richard Biener wrote:
> The following adds a heuristic to ifcombine that avoids turning
> analyzable loop exits into unanalyzable ones. This allows vectorizing
> the testcase in the PR again. I've refrained from actually
> analyzing niters but instead used a cheaper heuristic. I believe
> we'll only ever attempt to combine two ifs if they are in the same
> loop and if either both exit the loop or stay within.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
>
> PR tree-optimization/107690
> * tree-ssa-ifcombine.cc (ifcombine_ifandif): Do not merge
> possibly analyzable exit conditions.
>
> * g++.dg/vect/vect-pr107690.cc: New testcase.
I think this regressed
+FAIL: gcc.dg/guality/pr54693-2.c -O2 -DPREVENT_OPTIMIZATION line 21 x ==
10 - i
+FAIL: gcc.dg/guality/pr54693-2.c -O2 -flto -DPREVENT_OPTIMIZATION line 21 x
== 10 - i
+FAIL: gcc.dg/guality/pr54693-2.c -O2 -flto -flto-partition=none
-DPREVENT_OPTIMIZATION line 21 x == 10 - i
+FAIL: gcc.dg/guality/pr54693-2.c -O3 -fomit-frame-pointer -funroll-loops
-fpeel-loops -ftracer -finline-functions -DPREVENT_OPTIMIZATION line 21 x ==
10 - i
+FAIL: gcc.dg/guality/pr54693-2.c -O3 -g -DPREVENT_OPTIMIZATION line 21 x
== 10 - i
on i686-linux and
+FAIL: gcc.dg/guality/pr54693-2.c -O2 -DPREVENT_OPTIMIZATION line 21 x ==
10 - i
+FAIL: gcc.dg/guality/pr54693-2.c -O2 -flto -fno-use-linker-plugin
-flto-partition=none -DPREVENT_OPTIMIZATION line 21 x == 10 - i
+FAIL: gcc.dg/guality/pr54693-2.c -O3 -fomit-frame-pointer -funroll-loops
-fpeel-loops -ftracer -finline-functions -DPREVENT_OPTIMIZATION line 21 x ==
10 - i
+FAIL: gcc.dg/guality/pr54693-2.c -O3 -g -DPREVENT_OPTIMIZATION line 21 x
== 10 - i
on x86_64-linux.
Jakub
