[llvm] [SCEV] Preserve nuw on scaled recurrence start values. (PR #227458)

[Nikita Popov via llvm-commits]

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@@ -3331,8 +3331,12 @@ SCEVUse ScalarEvolution::getMulExpr(SmallVectorImpl<SCEVUse> &Ops,
       SCEVFlags Flags = AddRec->getNoWrapFlags(ComputeFlags({Scale, AddRec}));
 
       for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
+        // The initial product is evaluated on the first loop iteration; NUW
+        // also holds for this specific use.
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nikic wrote:

Why only nuw? Isn't this the same for nuw and nsw?

https://github.com/llvm/llvm-project/pull/227458