combine/dce patch for PR36003, PR42575

[Jeff Law]

On 07/01/10 17:03, Bernd Schmidt wrote:
> On 07/02/2010 12:48 AM, Hans-Peter Nilsson wrote:
>
>    
>> "So, I guess rtl.texi should change too?" (to
>> require a mode at the zero_extract rather than mentioning it to
>> default elsewhere).
>>      
> I'm not sure.  In theory it sounds like it would be better, but I think
> given past practice the compiler is prepared to deal with it, and I
> don't know whether all ports now define a mode for their zero_extracts.
>    
I don't think there has ever been a directive that they must; however, 
it's certainly advisable for ports to specify a mode on their extracts 
-- this is particularly true for ports where WORD_SIZE varies based on 
target switches.

jeff