* expr.c (convert_move): When a partial_int requires multiple
conversion steps, make sure successive steps convert the
intermediate value, not the original value.

* expmed.c (expand_mult): Convert partial_int multiplies to
shift/add combinations too.

* genmodes.c (mode_data): Add wider_2x.
(calc_wider_mode): Calculate twice-wider mode too.
(emit_mode_wider): Emit twice-wider mode too.
* machmode.h (mode_2xwider, GET_MODE_2XWIDER_MODE): New.
* expr.c (expand_expr_real_1): Use it for expanding
multiplies.

From-SVN: r100414