[llvm] [SROA] Pre-split overlapping move slices within a partition (PR #210061)

[Yonah Goldberg via llvm-commits]

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@@ -4867,7 +4904,9 @@ bool SROA::presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS) {
   for (auto &P : AS.partitions()) {
     for (Slice &S : P) {
       Instruction *I = cast<Instruction>(S.getUse()->getUser());
-      if (!S.isSplittable() || S.endOffset() <= P.endOffset()) {
+      bool ExtendsPastPartitionEnd = S.endOffset() > P.endOffset();
+      Slice *CopyOverlap = findOverlappingCopySlice(S, P);
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YonahGoldberg wrote:

Do you think its better to not be quadratic over the number of slices in the partition? You could get around this with a `DenseMap` from an instruction to the slice associated with that instruction.

https://github.com/llvm/llvm-project/pull/210061