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IRA patch: move clobbers downwards


This is an older patch I'm resubmitting.  The scheduler can move reg
clobbers away from the insns for which they were generated, generating a
window during which IRA thinks the register is live when it isn't.  This
can cause unnecessary conflicts.

The real problem here is that IRA does a backwards scan; just as in
peep2, it would probably be better to use a forwards scan using REG_DEAD
notes.  However, I'm told it's expensive to create those.

Bootstrapped and regression tested on i686-linux, also regression tested
on ARM.  Ok?


Bernd

Attachment: ira-clobber.diff
Description: Text document


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