[llvm] [VPlan] Model FOR resume value extraction in VPlan. (PR #93396)

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``````````bash
git-clang-format --diff c631131a1490af9f908a3a3be9aae5295ecff67d ac19de38509b88ce4259b7759e8be92b034fbbf6 -- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp llvm/lib/Transforms/Vectorize/VPlan.h llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
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View the diff from clang-format here.
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``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 0a3d9e0be8..7cc0959a0a 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -56,10 +56,10 @@
 #include "llvm/Transforms/Vectorize/LoopVectorize.h"
 #include "LoopVectorizationPlanner.h"
 #include "VPRecipeBuilder.h"
-#include "VPlanPatternMatch.h"
 #include "VPlan.h"
 #include "VPlanAnalysis.h"
 #include "VPlanHCFGBuilder.h"
+#include "VPlanPatternMatch.h"
 #include "VPlanTransforms.h"
 #include "VPlanVerifier.h"
 #include "llvm/ADT/APInt.h"
@@ -607,8 +607,8 @@ protected:
                     BasicBlock *MiddleBlock, BasicBlock *VectorHeader,
                     VPlan &Plan, VPTransformState &State);
 
-  /// Create the phi node for the resume value of first order recurrences in the scalar preheader and
-  /// update the users in the scalar loop.
+  /// Create the phi node for the resume value of first order recurrences in the
+  /// scalar preheader and update the users in the scalar loop.
   void fixFixedOrderRecurrence(VPLiveOut *LO, VPTransformState &State);
 
   /// Iteratively sink the scalarized operands of a predicated instruction into
@@ -3475,22 +3475,26 @@ void InnerLoopVectorizer::fixFixedOrderRecurrence(VPLiveOut *LO,
   // Extract the last vector element in the middle block. This will be the
   // initial value for the recurrence when jumping to the scalar loop.
   VPValue *VPExtract = LO->getOperand(0);
-using namespace llvm::VPlanPatternMatch;
-  assert(match(VPExtract, m_VPInstruction<VPInstruction::ExtractFromEnd>(m_VPValue(), m_VPValue())) && "FOR LiveOut expects to use an extract from end.");
+  using namespace llvm::VPlanPatternMatch;
+  assert(match(VPExtract, m_VPInstruction<VPInstruction::ExtractFromEnd>(
+                              m_VPValue(), m_VPValue())) &&
+         "FOR LiveOut expects to use an extract from end.");
   Value *ResumeScalarFOR = State.get(VPExtract, UF - 1, true);
 
   // Fix the initial value of the original recurrence in the scalar loop.
   Builder.SetInsertPoint(LoopScalarPreHeader, LoopScalarPreHeader->begin());
   PHINode *ScalarHeaderPhi = LO->getPhi();
-  auto *NewScalarHeaderPhi = Builder.CreatePHI(ScalarHeaderPhi->getType(), 2, "scalar.recur.init");
+  auto *NewScalarHeaderPhi =
+      Builder.CreatePHI(ScalarHeaderPhi->getType(), 2, "scalar.recur.init");
   auto *InitScalarFOR =
       ScalarHeaderPhi->getIncomingValueForBlock(LoopScalarPreHeader);
   for (auto *BB : predecessors(LoopScalarPreHeader)) {
     auto *Incoming = BB == LoopMiddleBlock ? ResumeScalarFOR : InitScalarFOR;
-    NewScalarHeaderPhi ->addIncoming(Incoming, BB);
+    NewScalarHeaderPhi->addIncoming(Incoming, BB);
   }
 
-  ScalarHeaderPhi->setIncomingValueForBlock(LoopScalarPreHeader, NewScalarHeaderPhi );
+  ScalarHeaderPhi->setIncomingValueForBlock(LoopScalarPreHeader,
+                                            NewScalarHeaderPhi);
   ScalarHeaderPhi->setName("scalar.recur");
 }
 
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index b75ff6621e..943edc3520 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -3166,7 +3166,9 @@ class VPlan {
   /// definitions are VPValues that hold a pointer to their underlying IR.
   SmallVector<VPValue *, 16> VPLiveInsToFree;
 
-  /// Values used outside the plan. It contains live-outs that need fixing. Any live-out that is fixed outside VPlan needs to be removed. The remaining live-outs are fixed via VPLiveOut::fixPhi.
+  /// Values used outside the plan. It contains live-outs that need fixing. Any
+  /// live-out that is fixed outside VPlan needs to be removed. The remaining
+  /// live-outs are fixed via VPLiveOut::fixPhi.
   MapVector<PHINode *, VPLiveOut *> LiveOuts;
 
   /// Mapping from SCEVs to the VPValues representing their expansions.
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 7a80babc13..75e2352f97 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -887,7 +887,7 @@ bool VPlanTransforms::adjustFixedOrderRecurrences(VPlan &Plan,
     //
     //   middle.block:
     //     s_penultimate = v2(2) = v3(3)
-		//     s_resume = v2(3)
+    //     s_resume = v2(3)
     //     br cond, scalar.ph, exit.block
     //
     //   scalar.ph:
@@ -903,13 +903,14 @@ bool VPlanTransforms::adjustFixedOrderRecurrences(VPlan &Plan,
     //
     //   exit.block:
     //     lo = lcssa.phi [s1, scalar.body], [s.penultimate, middle.block]
-     //
+    //
     // After execution completes the vector loop, we extract the next value of
     // the recurrence (x) to use as the initial value in the scalar loop. This
     // is modeled by ExtractFromEnd.
     Type *IntTy = Plan.getCanonicalIV()->getScalarType();
 
-    // Extract the penultimate value of the recurrence and update VPLiveOut users of the recurrence splice.
+    // Extract the penultimate value of the recurrence and update VPLiveOut
+    // users of the recurrence splice.
     auto *Penultimate = cast<VPInstruction>(MiddleBuilder.createNaryOp(
         VPInstruction::ExtractFromEnd,
         {FOR->getBackedgeValue(),

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https://github.com/llvm/llvm-project/pull/93396