[Bug tree-optimization/89134] A missing optimization opportunity for a simple branch in loop

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89134

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The issue is that GCC cannot prove finiteness of the loop since inc(i) could
just return i itself.  So I can't see how this optimization would be correct.

Note the loop isn't unswitched but only path-splitting exposes it.

And cddce then rightfully complains:

cannot prove finiteness of loop 2
Marking useful stmt: if (n_7(D) > i_10)

cannot prove finiteness of loop 1
Marking useful stmt: if (n_7(D) > i_16)