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Re: threading jumps makes niter changed from INTEGER_CST to chrec_dont_know


On 01/05/10 01:46, Eric Fisher wrote:
Hi,

I found that sometimes -fno-tree-dominator-opts will bring a big speed
promotion. This is because that pass_dominator tries to thread jumps.
But sometimes this will cause that the loop's exit bb does not
dominator its latch bb again. Then pass_complete_unroll is unable to
know the exact number of loop iteration and will not unroll the loop
completely again
Please file a bug report with a complete testcase so that we can see what's happening rather than trying to speculate.

jeff


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