[llvm] [SCEV] Try to re-use existing LCSSA phis when expanding SCEVAddRecExpr. (PR #147214)

[Florian Hahn via llvm-commits]

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@@ -1223,6 +1223,24 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
   return Result;
 }
 
+Value *SCEVExpander::tryToReuseLCSSAPhi(const SCEVAddRecExpr *S) {
+  const Loop *L = S->getLoop();
+  BasicBlock *EB = L->getExitBlock();
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fhahn wrote:

It should be possible to extend this to multi-exit loops, and just check for the exit dominating the insertion point as follow-up?

The main thing is that we need phis with single incoming values.

https://github.com/llvm/llvm-project/pull/147214