Remove condprop pass

[efriedma-quic]

Bugzilla Link	3906
Resolution	FIXED
Resolved on	Nov 10, 2009 23:56
Version	unspecified
OS	Linux
CC	@lattner,@echristo

Extended Description

Per summary, condprop should be removed.

As far as I can tell, simplifycfg knows how to do almost everything condprop knows how to do. condprop knows how to do four things: threading a conditional br on a PHI (dealt with in simplifycfg by FoldCondBranchOnPHI), threading a switch on a PHI (not dealt with in simplifycfg), constant folding terminators (dealt with in simplifycfg by a call to ConstantFoldTerminator), and merging a block with a single successor into that successor (dealt with in simplifycfg by a call to MergeBlockIntoPredecessor). It seems simple enough extend FoldCondBranchOnPHI to deal with switches; after that, condprop won't be doing anything that simplifycfg can't do.

[lattner]

FWIW, I agree

[efriedma-quic]

r69102 added another potentially interesting transformation, which is essentially a restricted form of tail duplication.

[lattner]

Jump threading does this transformation now:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20091005/088642.html

With recent changes, I'm thinking that jump threading and simplifycfg should be merged.

[lattner]

Condprop is now fully subsumed by jump threading and I switched standard passes to stop using it. Will remove it soon.

[lattner]

Fixed in r86810