[Bug sanitizer/87837] -O2 -fsanitize=signed-integer-overflow misses overflows on x86-64

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87837

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
The corresponding match.pd transformation already checks
TYPE_OVERFLOW_UNDEFINED, which apparently is not sufficient. That's
inconvenient, -ftrapv does change the value of that macro.