[Bug c++/127434] [14/15/16/17 regression] IPA-SRA introduces unconditional load from conditionally accessed indexing header at -O2

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127434

--- Comment #5 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Note even a C testcase would violate parts of the C standard.

Mainly this part: "Out-of-Bounds/Invalid Pointer Arithmetic" is similar between
C and C++ so creating a pointer to before a valid object is undefined.