[PATCH] D48202: Generalize MergeBlockIntoPredecessor. Replace uses of MergeBasicBlockIntoOnlyPred.

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea marked 4 inline comments as done.
asbirlea added a comment.

Updated scev.ll to be fully parametric (vs updating one label).  All other tests should use variables as well, but that can be a separate cleanup.



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Comment at: lib/Transforms/Utils/BasicBlockUtils.cpp:146
   // Can't merge if there are multiple successors.
   if (!OnlySucc) return false;
 
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dmgreen wrote:
> asbirlea wrote:
> > dmgreen wrote:
> > > This and the previous block is just (PredBB->getUniqueSuccessor() == BB)?
> > This method is expected to also merge blocks when there are multiple edges from PredBB to BB.
> > Example: `test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch.ll: test3`
> > 
> > ```
> > Start:          ; preds = %0
> >   switch i32 3, label %TheDest [
> >   i32 0, label %TheDest
> >   i32 1, label %TheDest
> >   i32 2, label %TheDest
> >   i32 5, label %TheDest
> >   ]
> > TheDest:
> >   ret i32 1234
> > ```
> I believe this is what getUniqueSuccessor does (as opposed to getSingleSuccessor). You are not making things any worse by leaving it as it is though.
Ah, I missed the difference from getSingleSuccessor. Thank you for following up!


Repository:
  rL LLVM

https://reviews.llvm.org/D48202