[Bug rtl-optimization/57281] [4.9 Regression] x86_64-linux loop fails to terminate at -O3 -m32

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57281

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|target                      |rtl-optimization
            Summary|[4.9 Regression]            |[4.9 Regression]
                   |x86_64-linux loop fails to  |x86_64-linux loop fails to
                   |terminate at -O3 -m32,      |terminate at -O3 -m32
                   |bogus extendsidi2_1         |
                   |splitter                    |

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
postreload leaves a REG_DEAD note on the

(insn 19 78 21 4 (parallel [
            (set (mem:DI (reg/f:SI 3 bx [orig:68 D.1736 ] [68]) [4 *_18+0 S8
A64])
                (sign_extend:DI (reg:SI 0 ax [orig:75 b ] [75])))
            (clobber (reg:CC 17 flags))
            (clobber (reg:SI 1 dx [80]))
        ]) t.c:9 137 {extendsidi2_1}
     (expr_list:REG_UNUSED (reg:SI 1 dx [80])
        (expr_list:REG_DEAD (reg:SI 0 ax [orig:75 b ] [75])
            (nil))))

which is bogus.