On Wed, Nov 26, 2014 at 11:14:36AM -0700, Jeff Law wrote:
> >Are you talking about create_log_links?  There can be no duplicates there
> >(anymore), that would be multiple defs of the same reg in the same insn,
> >indeed.
> Yes, I was referring to the code in create_log_links.  You dropped the 
> check for duplicate links.  It caught my eye when reading the changes, 
> but then I realized the check may no longer be necessary.
> 
> Hmm, what about an insn that has two destinations, which happen to be 
> upper and lower SUBREGs of a pseudo.  Would that create duplicate links 
> after your change?

Yes it would.  And I'm not so certain distribute_log_links handles that
situation gracefully.  Rats.

IMNSHO such RTL should be invalid (it can always be written simpler as
one SET); but there seems to be no such rule.

I'll add the check back.

Wouldn't it be lovely if we could just use DF here...


Segher

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