[Bug tree-optimization/33535] New: bitpos_of_field() returns false result base of hard coded multiplication by 8

[tomerben at ceva-dsp dot com]

Taken from tree-ssa-structalias.c:
The original code:

static unsigned HOST_WIDE_INT
bitpos_of_field (const tree fdecl)
{

  if (TREE_CODE (DECL_FIELD_OFFSET (fdecl)) != INTEGER_CST
      || TREE_CODE (DECL_FIELD_BIT_OFFSET (fdecl)) != INTEGER_CST)
    return -1;

  return (tree_low_cst (DECL_FIELD_OFFSET (fdecl), 1) * 8) 
    + tree_low_cst (DECL_FIELD_BIT_OFFSET (fdecl), 1);
}

I think the code needs to be:

static unsigned HOST_WIDE_INT
bitpos_of_field (const tree fdecl)
{

  if (TREE_CODE (DECL_FIELD_OFFSET (fdecl)) != INTEGER_CST
      || TREE_CODE (DECL_FIELD_BIT_OFFSET (fdecl)) != INTEGER_CST)
    return -1;

  return (tree_low_cst (DECL_FIELD_OFFSET (fdecl), 1) * BITS_PER_UNIT) 
         + tree_low_cst (DECL_FIELD_BIT_OFFSET (fdecl), 1);
}

The offset in bits need to consider the BITS_PER_UNIT macro instead of hard
coded 8. This is usefull for machines that have different value of
BITS_PER_UNIT (16 for e.g. on the port I'm working on).


-- 
           Summary: bitpos_of_field() returns false result base of hard
                    coded multiplication by 8
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tomerben at ceva-dsp dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33535