2004-10-18  Pat Haugen  <pthaugen@us.ibm.com>

        * simplify-rtx.c (mode_signbit_p): Externalize function...
        * rtl.h (mode_signbit_p): ... to here.
        * combine.c (simplify_shift_const): Recognize PLUS signbit as
        canonical form of XOR signbit and move to outer op.

From-SVN: r89235