combine/dce patch for PR36003, PR42575

[Paolo Bonzini]

On 06/28/2010 11:47 AM, Eric Botcazou wrote:
>> single_set would be a better match, no?
>
> What do you mean exactly?  That single_set returns NULL_RTX for PARALLEL?

That it doesn't return NULL_RTX for CLOBBERs, USEs, or SETs whose output 
will not be used (like, most of the time, the CC set).

Paolo