Merge r345353 into the 7.0 branch : Teach the DominatorTree fallback to recalculation when applying updates to speedup JT (#37929 )

[llvmbot]

Bugzilla Link	39584
Resolution	FIXED
Resolved on	Nov 19, 2018 19:42
Version	7.0
OS	All
Blocks	#38454
Reporter	LLVM Bugzilla Contributor
CC	@tstellar
Fixed by commit(s)	r345353 r347285

Extended Description

Is it OK to merge the following revision(s) to the 7.0 branch?

[llvmbot]

assigned to @kuhar

[llvmbot]

https://reviews.llvm.org/rL345353

[llvmbot]

r345353 fixes a regression in v7.0, which makes JumpThreading take an unacceptable amount of time on some inputs.

Relevant bug: #37277
Review link: https://reviews.llvm.org/D53245

[llvmbot]

Rewording:

r345353 fixes a regression which makes JumpThreading take an unacceptable amount of time on some inputs in v7.0.

[tstellar]

Jakub,

You reviewed this patch, what do you think about merging this?

[kuhar]

This should be safe to merge, I don't know of any regression caused by the patch, while it solves some known (slowness) bugs.

[tstellar]

Merged: r347285