Haicheng Wu a6a3279bd3 [JumpThreading] Split select that has constant conditions coming from the PHI node ...

Look for PHI/Select in the same BB of the form

bb:
  %p = phi [false, %bb1], [true, %bb2], [false, %bb3], [true, %bb4], ...
  %s = select p, trueval, falseval

And expand the select into a branch structure. This later enables
jump-threading over bb in this pass.

Using the similar approach of SimplifyCFG::FoldCondBranchOnPHI(), unfold
select if the associated PHI has at least one constant.  If the unfolded
select is not jump-threaded, it will be folded again in the later
optimizations.

llvm-svn: 257198

2016-01-08 19:39:39 +00:00

7.6 KiB

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