[Bug rtl-optimization/89435] [7/8/9 Regression] wrong code with -O1 -march=armv4 -fno-forward-propagate with __builtin_sub_overflow()

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89435

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #9 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
It's exactly the same underlying issue: the combiner first eliminates an AND
(or an equivalent ZERO_EXTEND) between 2 instructions as redundant, which is OK
in isolation, but IRA (combine_and_move_insns) later combines again the same 2
instructions without using the WORD_REGISTER_OPERATIONS semantics used in the
combiner.

*** This bug has been marked as a duplicate of bug 89795 ***