[Bug middle-end/91450] __builtin_mul_overflow(A,B,R) wrong code if product < 0, *R is unsigned, and !(A&B)

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91450

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 47290
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47290&action=edit
gcc10-pr91450.patch

Untested fix.