[llvm] [VPlan] Optimize FindLast of (binop %IV, live-in) by sinking. (PR #183911)

[Florian Hahn via llvm-commits]

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@@ -5664,6 +5663,43 @@ void VPlanTransforms::addExitUsersForFirstOrderRecurrences(VPlan &Plan,
   }
 }
 
+/// Check if \p V is a binary expression of a widened IV and a loop-invariant
+/// value. Returns the widened IV if found, nullptr otherwise.
+static VPWidenIntOrFpInductionRecipe *
+getExpressionIV(VPValue *V, VPRegionBlock *VectorLoopRegion) {
+  auto *BinOp = dyn_cast<VPWidenRecipe>(V);
+  if (!BinOp || !Instruction::isBinaryOp(BinOp->getOpcode()))
+    return nullptr;
+
+  VPWidenIntOrFpInductionRecipe *WideIV = nullptr;
+  for (VPValue *Op : BinOp->operands()) {
+    // Operands must be a single IV and others must be loop invariant.
+    auto *Cand = dyn_cast<VPWidenIntOrFpInductionRecipe>(Op);
+    if (Cand) {
+      if (WideIV)
+        return nullptr;
+      WideIV = Cand;
+      continue;
+    }
+    if (!Op->isDefinedOutsideLoopRegions())
+      return nullptr;
+  }
+  return WideIV;
+}
+
+/// Create a scalar version of the binary op \p V in the middle block,
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fhahn wrote:

updated thanks

https://github.com/llvm/llvm-project/pull/183911