[Bug middle-end/115999] a - (a>>31) should be transformed into a + ((unsigned)a)>>31 (for signed a)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115999

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Sounds reasonable - btw, this is a quite special case.  Do we
canonicalize (unsigned)(a < 0) as ((unsigned)a >> 31)?