[Bug target/107172] [13 Regression] wrong code with "-O1 -ftree-vrp" on x86_64-linux-gnu since r13-1268-g8c99e307b20c502e

[roger at nextmovesoftware dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107172

--- Comment #47 from Roger Sayle <roger at nextmovesoftware dot com> ---
I really don't believe that using UNSPEC here is the correct way to go, but it
appears to be the (only?) approach that Segher is prepared to approve.  Hohum.