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

[Florian Hahn via llvm-commits]

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@@ -500,26 +500,23 @@ class InnerLoopVectorizer {
   InnerLoopVectorizer(Loop *OrigLoop, PredicatedScalarEvolution &PSE,
                       LoopInfo *LI, DominatorTree *DT,
                       const TargetTransformInfo *TTI, AssumptionCache *AC,
-                      ElementCount VecWidth,
-                      ElementCount MinProfitableTripCount,
-                      unsigned UnrollFactor, LoopVectorizationCostModel *CM,
-                      BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI,
-                      GeneratedRTChecks &RTChecks, VPlan &Plan)
+                      ElementCount VecWidth, unsigned UnrollFactor,
+                      LoopVectorizationCostModel *CM, BlockFrequencyInfo *BFI,
+                      ProfileSummaryInfo *PSI, GeneratedRTChecks &RTChecks,
+                      VPlan &Plan)
       : OrigLoop(OrigLoop), PSE(PSE), LI(LI), DT(DT), TTI(TTI), AC(AC),
-        VF(VecWidth), MinProfitableTripCount(MinProfitableTripCount),
-        UF(UnrollFactor), Builder(PSE.getSE()->getContext()), Cost(CM),
-        BFI(BFI), PSI(PSI), RTChecks(RTChecks), Plan(Plan),
+        VF(VecWidth), UF(UnrollFactor), Builder(PSE.getSE()->getContext()),
+        Cost(CM), BFI(BFI), PSI(PSI), RTChecks(RTChecks), Plan(Plan),
         VectorPHVPBB(cast<VPBasicBlock>(
             Plan.getVectorLoopRegion()->getSinglePredecessor())) {}
 
   virtual ~InnerLoopVectorizer() = default;
 
-  /// Create a new empty loop that will contain vectorized instructions later
-  /// on, while the old loop will be used as the scalar remainder. Control flow
-  /// is generated around the vectorized (and scalar epilogue) loops consisting
-  /// of various checks and bypasses. Return the pre-header block of the new
-  /// loop. In the case of epilogue vectorization, this function is overriden to
-  /// handle the more complex control flow around the loops.
+  /// Create new basic blocks needed as entries and exits of the code generated
+  /// by executing a VPlan. For epilogue vectorization, it will create blocks
+  /// for the minimum iteration checks and IR basic blocks for the vector and
+  /// scalar preheaders. Otherwise it will create a basic block for the scalar
+  /// preheader only.
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fhahn wrote:

Thanks, updated to say what it returns here and that it is specialized 

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