[llvm] [VPlan] Lower BranchOnTwoConds to chain of 2 simple branches. (PR #174016)

[via llvm-commits]

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@@ -8,13 +8,13 @@ compound=true
   ]
   N1 -> N2 [ label=""]
   N2 [label ="vector.body"]
+  N2 -> N5 [ label=""]
   N2 -> N4 [ label=""]
-  N2 -> N2 [ label="" dir=back]
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ayalz wrote:

Perhaps it's worth retaining this "middle.split" figure, along with some explanation, e.g., that early-exit could be (and has been) folded into the latch of the vector loop thereby producing a vector loop with a single exiting block (the latch) and a single exit block (middle split); but having instead an early exiting block from the vector loop separate from the latch with its trip count condition is found to be more efficient plus helps clarify to SCEV the loop's maximal trip count.

https://github.com/llvm/llvm-project/pull/174016