[VPlan] Don't look up recipe for IV step via RecipeBuilder. (NFC)

Directly update induction increments with step value created for wide
inductions in createWidenInductionRecipes, which does not require
looking up via RecipeBuilder.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -7633,6 +7633,14 @@ createWidenInductionRecipes(VPInstruction *PhiR,
 
   VPValue *Step =
       vputils::getOrCreateVPValueForSCEVExpr(Plan, IndDesc.getStep());
+
+  // Update wide induction increments to use the same step as the corresponding
+  // wide induction. This enables detecting induction increments directly in
+  // VPlan and removes redundant splats.
+  using namespace llvm::VPlanPatternMatch;
+  if (match(PhiR->getOperand(1), m_Add(m_Specific(PhiR), m_VPValue())))
+    PhiR->getOperand(1)->getDefiningRecipe()->setOperand(1, Step);
+
   PHINode *Phi = cast<PHINode>(PhiR->getUnderlyingInstr());
   return new VPWidenIntOrFpInductionRecipe(Phi, Start, Step, &Plan.getVF(),
                                            IndDesc, PhiR->getDebugLoc());
@@ -8473,20 +8481,6 @@ VPlanPtr LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(
          "entry block must be set to a VPRegionBlock having a non-empty entry "
          "VPBasicBlock");
 
-  // Update wide induction increments to use the same step as the corresponding
-  // wide induction. This enables detecting induction increments directly in
-  // VPlan and removes redundant splats.
-  for (const auto &[Phi, ID] : Legal->getInductionVars()) {
-    auto *IVInc = cast<Instruction>(
-        Phi->getIncomingValueForBlock(OrigLoop->getLoopLatch()));
-    if (IVInc->getOperand(0) != Phi || IVInc->getOpcode() != Instruction::Add)
-      continue;
-    VPWidenInductionRecipe *WideIV =
-        cast<VPWidenInductionRecipe>(RecipeBuilder.getRecipe(Phi));
-    VPRecipeBase *R = RecipeBuilder.getRecipe(IVInc);
-    R->setOperand(1, WideIV->getStepValue());
-  }
-
   // TODO: We can't call runPass on these transforms yet, due to verifier
   // failures.
   VPlanTransforms::addExitUsersForFirstOrderRecurrences(*Plan, Range);

llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h

@@ -496,6 +496,12 @@ m_c_Binary(const Op0_t &Op0, const Op1_t &Op1) {
   return AllRecipe_commutative_match<Opcode, Op0_t, Op1_t>(Op0, Op1);
 }
 
+template <typename Op0_t, typename Op1_t>
+inline AllRecipe_match<Instruction::Add, Op0_t, Op1_t> m_Add(const Op0_t &Op0,
+                                                             const Op1_t &Op1) {
+  return m_Binary<Instruction::Add, Op0_t, Op1_t>(Op0, Op1);
+}
+
 template <typename Op0_t, typename Op1_t>
 inline AllRecipe_commutative_match<Instruction::Add, Op0_t, Op1_t>
 m_c_Add(const Op0_t &Op0, const Op1_t &Op1) {