[llvm] [SLPVectorizer] Use accurate cost for external users of resize shuffles (PR #137419)

[Jeffrey Byrnes via llvm-commits]

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@@ -14802,7 +14803,39 @@ InstructionCost BoUpSLP::getTreeCost(ArrayRef<Value *> VectorizedVals,
                  << " for final shuffle of insertelement external users.\n";
           TE->dump(); dbgs() << "SLP: Current total cost = " << Cost << "\n");
       Cost += C;
-      return std::make_pair(TE, true);
+
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jrbyrnes wrote:

Thanks -- I'll try to adopt it, but it's causing some concerning looking diffs in the lit tests that I need to work through.

https://github.com/llvm/llvm-project/pull/137419