[llvm] [VPlan] Remove VPBlendRecipe and replace with select VPInstructions (PR #150369)

[Ramkumar Ramachandra via llvm-commits]

================
@@ -4203,10 +4202,13 @@ VectorizationFactor LoopVectorizationPlanner::selectVectorizationFactor() {
           if (!VPI)
             continue;
           switch (VPI->getOpcode()) {
-          // Selects are only modelled in the legacy cost model for safe
-          // divisors.
           case Instruction::Select: {
             VPValue *VPV = VPI->getVPSingleValue();
+            // Blend selects are modelled in VPlan.
+            if (isa_and_nonnull<PHINode>(VPV->getUnderlyingValue()))
+              continue;
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artagnon wrote:

```suggestion
              continue;

```

https://github.com/llvm/llvm-project/pull/150369