[trunk] Addition to subreg section of rtl.text.

[Paolo Bonzini]

Richard Sandiford wrote:
> Paolo Bonzini <bonzini@gnu.org> writes:
>>> I think one reason is that allowing zero_extracts of multi-word modes is
>>> (like this subreg thing) a little hard to pin down.  What happens when
>>> WORDS_BIG_ENDIAN && !BYTES_BIG_ENDIAN
>> Unless I had my grep wrong, the only such machines to do this are PDP11 
>> and ARM with special flags (-mbig-endian -mwords-little-endian) that 
>> were "for backward compatibility with older versions of GCC" in 1999 [1].
>>
>> So, is this special case worth keeping?
> 
> Good question.  Unless I'm missing something, PDP11 isn't yet on the
> deprecrated list.  Is that right?  If so, I suppose we can't remove
> it before 4.5 at the earliest.

It was in the 4.3 list, then Paul Koning stepped up to do some work on 
it but then nothing happened.

[context for Paul: PDP-11 is the last target for which BYTES_BIG_ENDIAN 
!= WORDS_BIG_ENDIAN]

http://gcc.gnu.org/ml/gcc/2008-01/msg00339.html

Paolo