[Bug target/106755] Incorrect code gen for altivec intrinsics with constant inputs

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106755

--- Comment #5 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to Peter Bergner from comment #2)
> So the tests (I've removed all static inline usage and always use
> -fno-inline) pass with -O1 and fail with -O2 and -O3.  Looking at all of the
> optimizations enabled by -O2 that are not in -O1 and using -fno-* for them,
> the only option that allows the tests to pass with -O2 is
> -fno-strict-aliasing.  That said, -Wall and -Wstrict-aliasing do not flag
> any warnings with the code.  I suppose they could miss some issues in the
> test case code???

There are 10 cases (in just the .cc files) that use "optimize > 1", and
another 5 that do "optimize >= 2".

The -O options do more than just being shorthand for some -f option selections.