On Tue, 3 Apr 2012, Eric Botcazou wrote: > > For the case in question offset is (D.2640_7 + -1) * 20 + 16. I wonder > > why DECL_FIELD_OFFSET of the outermost COMPONENT_REF is not added > > to bitpos by get_inner_reference (that is what get_bit_range assumes ...). > > DECL_FIELD_OFFSET is added to offset and DECL_FIELD_BIT_OFFSET to bitpos. > > > So, how would you make sure this works? Match the fact that > > get_inner_reference does _not_ add DECL_FIELD_OFFSET to bitpos, > > and, if DECL_FIELD_OFFSET is an INTEGER_CST simply subtract that > > from offset and add it to bitpos? I suppose that would work. > > Yes, but the amount is simply the negative bitstart (which is a multiple of > BITS_PER_UNIT). This is the same kind of adjustment now done at the end of > get_inner_reference to avoid negative bit positions there too. > > > Though doing that in get_inner_reference for DECL_BIT_FIELD_TYPE > > fields may make sense as well. > > That would be more complicated, as we would need to split the offset into > variable and fixed part. > > > Tentative patch attached, regtested for Ada on x86 and x86-64. I'll do a > full > testing cycle if it is approved.
Yes, the patch is ok. Thanks, Richard. > > * expr.c (get_bit_range): Add OFFSET parameter and adjust BITPOS. > Change type of BITOFFSET to signed. Make sure the lower bound of > the computed range is non-negative by adjusting OFFSET and BITPOS. > (expand_assignment): Adjust call to get_bit_range.
