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Re: [PATCH] Disable CSE skip-blocks


> With just cse-follow-jumps, CSE works on extended basic blocks, which
> is really as simple as we should go I think. Doing CSE only locally
> requires more work (like fwprop) to catch some simple things.

CSE already worked on extended basic blocks before cse-follow-jumps
because it would go through the jump in the fallthrough direction.
What that switch does is to make it go in BOTH directions.  And that's
the very expensive pass.

> So again, that is *not* my intent.  If someone wants to investigate
> this, I can only encourage that, but I'm not going to do it.

Sorry, I was talking about understand just what we miss with disabling
-fcse-skip-blocks, at least at this time.  My remarks about both were
meant to be very general.  I'm all in favor of disabling and then
removing -fcse-skip-blocks, but I think that before we do so (and
hence while we still can) we should analyze what we miss that it's
catching since that should be the empty set.


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