[Bug target/21017] ppc 64bit target not using rlwinm

Tue Sep 6 00:37:00 GMT 2005

------- Additional Comments From amodra at bigpond dot net dot au  2005-09-06 00:37 -------
Yes, we get
(ior:SI (lshiftrt:SI (subreg:SI (reg/v:DI 119 [ x ]) 4)
        (const_int 16 [0x10]))
    (subreg:SI (ashift:DI (reg/v:DI 119 [ x ])
            (const_int 16 [0x10])) 4))
which doesn't match the test in simplify_logical to simplify to a rotate.

The second operand of ior has been "simplified" by simplify_shift_const from
(ashift:SI (subreg:SI (reg/v:DI 119 [ x ]) 4) (const_int 16 [0x10])), which, if
it was left that way, would allow a match.  I think simplify_shift_const is OK
in what it's doing, ie. it is a useful optimisation in other cases, so I'll see
about matching the subreg pattern in simplify_logical.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21017