[llvm] [VectorCombine] Fold binary op of reductions. (PR #121567)

[Simon Pilgrim via llvm-commits]

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@@ -60,6 +60,12 @@ static cl::opt<unsigned> MaxInstrsToScan(
     "vector-combine-max-scan-instrs", cl::init(30), cl::Hidden,
     cl::desc("Max number of instructions to scan for vector combining."));
 
+static cl::opt<bool> ForceFoldBinopOfReductions(
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RKSimon wrote:

Do we need this any more? It'd be better if the fold was purely cost driven like most vectorcombiner folds.

https://github.com/llvm/llvm-project/pull/121567