[llvm] [VPlan] Return Max from computeCost without underlying instrs. (PR #109708)

[Florian Hahn via llvm-commits]

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@@ -844,7 +844,9 @@ class VPRecipeBase : public ilist_node_with_parent<VPRecipeBase, VPBasicBlock>,
 protected:
   /// Compute the cost of this recipe either using a recipe's specialized
   /// implementation or using the legacy cost model and the underlying
-  /// instructions.
+  /// instructions. Returns InstructionCost::max() if the cost of this recipe
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fhahn wrote:

Yes, also there are some computeCost implementation for recipes with underlying instruction, for which the default should not trigger. In particular, all recipes which currently have computeCost implemented in subclasses should be included with force-target-instruction-cost.

https://github.com/llvm/llvm-project/pull/109708