[llvm] [SLP]Emit actual bitwidth for analyzed MinBitwidth nodes, NFCI. (PR #71536)

[Simon Pilgrim via llvm-commits]

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@@ -7911,6 +7935,42 @@ BoUpSLP::getEntryCost(const TreeEntry *E, ArrayRef<Value *> VectorizedVals,
         }
 
         InstructionCost VecCost = VectorCost(CommonCost);
+        // Check if the current node must be resized, if the parent node is not
+        // resized.
+        if (!UnaryInstruction::isCast(E->getOpcode()) && E->Idx != 0 &&
+            (E->UserTreeIndices.front().UserTE->getOpcode() !=
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RKSimon wrote:

Pull out E->UserTreeIndices.front() ref? Its called a lot below.

https://github.com/llvm/llvm-project/pull/71536