va_arg and Alignment

[Aldy Hernandez]

>>>>> "D" == D Towner <towner@compsci.bristol.ac.uk> writes:

 > The call to `f' is correctly initialised, with the long value being
 > aligned on a 32-bit boundary. However, within `f', the va_arg line will
 > try to load the long value from a location which isn't on the correct
 > boundary (i.e., the 16-bit address of the last named parameter +
 > 16-bits).

You probably have to code your own vaarg implementation.

Look in the ppc port at:

	rs6000_va_arg
	rs6000_va_start
	rs6000_build_va_list

particularly this code in va_start:

  /* Care for on-stack alignment if needed.  */
  if (rsize <= 1)
    t = ovf;
  else
    {
      int align;

      /* Vectors are 16 byte aligned.  */
      if (TREE_CODE (type) == VECTOR_TYPE)
        align = 15;
      else
        align = 7;

      t = build (PLUS_EXPR, TREE_TYPE (ovf), ovf, build_int_2 (align, 0));
      t = build (BIT_AND_EXPR, TREE_TYPE (t), t, build_int_2 (-align-1, -1));
    }

i just fixed this today :)

cheers
aldy