[Bug tree-optimization/115337] wrong code with _BitInt() __builtin_stdc_first_leading_one/__builtin_clzg (with -1 as second arg) at -O2

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115337

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 58341
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58341&action=edit
gcc15-pr115337-3.patch

Improve ranger handling of .CLZ (x, -1).  As the stdbit.h builtins now use
that value, it is worth special casing it in the CLZ handling, so that we get
e.g. [-1, 128] range rather than VARYING.