[llvm] [VPlan] Add VPlan-based addMinIterCheck, replace ILV for non-epilogue. (PR #153643)

[via llvm-commits]

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@@ -2456,53 +2430,9 @@ static void addFullyUnrolledInstructionsToIgnore(
 }
 
 BasicBlock *InnerLoopVectorizer::createVectorizedLoopSkeleton() {
-  /*
-   In this function we generate a new loop. The new loop will contain
-   the vectorized instructions while the old loop will continue to run the
-   scalar remainder.
-
-       [ ] <-- old preheader - loop iteration number check and SCEVs in Plan's
-     /  |      preheader are expanded here. Eventually all required SCEV
-    /   |      expansion should happen here.
-   /    v
-  |    [ ] <-- vector loop bypass (may consist of multiple blocks).
-  |  /  |
-  | /   v
-  ||   [ ]     <-- vector pre header.
-  |/    |
-  |     v
-  |    [  ] \
-  |    [  ]_|   <-- vector loop (created during VPlan execution).
-  |     |
-  |     v
-  \   -[ ]   <--- middle-block (wrapped in VPIRBasicBlock with the branch to
-   |    |                       successors created during VPlan execution)
-   \/   |
-   /\   v
-   | ->[ ]     <--- new preheader (wrapped in VPIRBasicBlock).
-   |    |
- (opt)  v      <-- edge from middle to exit iff epilogue is not required.
-   |   [ ] \
-   |   [ ]_|   <-- old scalar loop to handle remainder (scalar epilogue, header
-   |    |          wrapped in VPIRBasicBlock).
-    \   |
-     \  v
-      >[ ]     <-- exit block(s). (wrapped in VPIRBasicBlock)
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ayalz wrote:

Perhaps this may fit somewhere at the outset. OTOH seems somewhat obsolete - needs to consider epilog vectorization, early exit.

https://github.com/llvm/llvm-project/pull/153643