[llvm] [LV] Transform to handle exits in the scalar loop (PR #148626)

[David Sherwood via llvm-commits]

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@@ -4224,12 +4232,17 @@ class VPlan {
   /// Returns the preheader of the vector loop region, if one exists, or null
   /// otherwise.
   VPBasicBlock *getVectorPreheader() {
+    if (EarlyExitPreheader)
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david-arm wrote:

I think in vplan this type of thing is typically discouraged, i.e. wherever possible we should walk the CFG to find the block so that we don't have the burden of maintaining the EarlyExitPreheader during CFG optimisations. @fhahn any thoughts?

https://github.com/llvm/llvm-project/pull/148626