Refine cross-jumping

Jan Hubicka jh@suse.cz
Sat Apr 19 17:50:00 GMT 2003


>     How much of opurtunities we miss this way?  Perhaps we can simply merge
>     the blocks conservativly (ie remove the clobbers and keep uses)
> 
> I didn't measure, but I doubt it misses very many.  After all, each
> such "miss" would have caused this bug and it didn't occur in very many places.
> I don't think it's worth the complexity.

It used to make important difference (about 20% of crossjumping).  I
know that because my original crossjumping rewrite didn't contained that
and I had to put the hack in from old code in order to make results
comparable.
We reduced the amount of clobbers/uses in the code since that but still
it may be important.   It usually gets things right (modulo confusing
liveness analysis).  Only case I can think of where it produces invalid
code is when use gets lost.

Honza



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