https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101701
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #5 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> So the problem here is iftoswitch should ignore if it is profitable to
> convert the ifs to a switch statement (unless there are only two ifs) and
> then allow the switchlower pass to lower the switch again.
This was my original intention, but Jakub wanted to make the if-to-switch
transformation
only conditionally based on the ability to make a jump table or a bit-test.
Reason is that
some optimization passes work only on series of gimple conditions.
>
> So x86 we get:
> ;; Canonical GIMPLE case clusters: 1 2 3 4
> For foo
> and then for bar:
> ;; Canonical GIMPLE case clusters: 1 2 3 4
> ;; BT can be built: BT(values:4 comparisons:8 range:4 density: 200.00%):1-4
> /app/example.cpp:10:21: optimized: Condition chain with 4 BBs transformed
> into a switch statement.
In my case, it's not transformed as we do JT at least for 5 cases:
unsigned int
default_case_values_threshold (void)
{
return (targetm.have_casesi () ? 4 : 5);
}
That's why you see a different codegen on ARM target.
