> Yes, I realize that, but it looks like that code is not doing > something because old integrate.c choked on it. Quoting that part of > the patch: > > Index: expmed.c > =================================================================== > --- expmed.c (revision 187936) > +++ expmed.c (working copy) > @@ -1866,6 +1866,9 @@ extract_fixed_bit_field (enum machine_mode tmode, > shift it so it does. */ > /* Maybe propagate the target for the shift. */ > /* But not if we will return it--could confuse integrate.c. */ > + /* ??? What does the above comment mean in relation to the code > + below? NB, integrate.c is no more, so I guess it can't be > + confused by anything anymore... */ > rtx subtarget = (target != 0 && REG_P (target) ? target : 0); > if (tmode != mode) subtarget = 0; > op0 = expand_shift (RSHIFT_EXPR, mode, op0, bitpos, subtarget, 1); > > Does that "But not if..." comment refer to the "if (tmode != mode) > subtarget = 0;" line? Of so, can/should we drop that line (as well as > the comment)? I don't know this part of the compiler well enough to > tell.
I don't think it's a direct reference. There is the same pattern at the end of the function, where TARGET has already been zeroed if mode != tmode. If the mode don't match, expand_shift cannot reuse [SUB]TARGET as-is, so the code consistently avoids to pass it. I'd just drop the dangling reference to integrate.c and reformat the line if (tmode != mode) subtarget = 0; into if (mode != mode) subtarget = 0; to make it more closely ressemble the other instance. -- Eric Botcazou
