Fold "and (LOAD P), 255" -> zextload. This allows us to compile:

unsigned foo3(unsigned *P) { return *P & 255; }
as:
_foo3:
        lbz r3, 3(r3)
        blr

instead of:

_foo3:
        lwz r2, 0(r3)
        rlwinm r3, r2, 0, 24, 31
        blr

and:

unsigned short foo2(float a) { return a; }

as:
_foo2:
        fctiwz f0, f1
        stfd f0, -8(r1)
        lhz r3, -2(r1)
        blr

instead of:

_foo2:
        fctiwz f0, f1
        stfd f0, -8(r1)
        lwz r2, -4(r1)
        rlwinm r3, r2, 0, 16, 31
        blr

llvm-svn: 26417