bit shifting CQImode values

[Alan Modra]

This hunk of code I added to calls.c around line 1646 is buggy.

#ifdef BLOCK_REG_PADDING
	      /* Handle case where we have a value that needs shifting
		 up to the msb.  eg. a QImode value and we're padding
		 upward on a BYTES_BIG_ENDIAN machine.  */
	      if (nregs == -1)
		{
		  rtx ri = gen_rtx_REG (word_mode, REGNO (reg));
		  rtx x;
		  int shift = (UNITS_PER_WORD - size) * BITS_PER_UNIT;
		  x = expand_binop (word_mode, ashl_optab, mem,
				    GEN_INT (shift), ri, 1, OPTAB_WIDEN);
		  if (x != ri)
		    emit_move_insn (ri, x);
		}

The problem being that expand_binop doesn't handle the case when "mem"
is something like (mem/s:CQI (reg/f:DI 118) [0 g1sScc1+0 S2 A8]).  I
guess it's not reasonable to expect expand_binop to do what I want here,
and that I need to somehow "flatten" the mem to HImode.  Either that,
or load the mem to a CQI reg then change the reg mode.  What's the
right way to do this?

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre