[llvm-commits] [PATCH] Make SimplifyCFGPass preserve the dominator tree

[Peter Cooper]

Hi all

Attached is a pass to make the SimplifyCFGPass preserve the dominator tree.  Currently we see lots of recalculations of the dom tree right after simplify cfg runs, regardless of whether simplify cfg actually did anything.

This pass explicitly recalculates the dom tree if simplify cfg did anything, but otherwise just leaves it preserved so we recalculate less often.

Also, i'm open to suggestions for a better way to do this.  Ideally the pass manager could track this but not all passes return true from their run functions when they actually make a change.

Thanks,
Pete
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