[llvm] [LAA] Be more careful when evaluating AddRecs at symbolic max BTC. (PR #128061)

[David Sherwood via llvm-commits]

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@@ -188,9 +188,56 @@ RuntimeCheckingPtrGroup::RuntimeCheckingPtrGroup(
   Members.push_back(Index);
 }
 
+/// Return true, if evaluating \p AR at \p MaxBTC cannot wrap, because \p AR at
+/// \p MaxBTC is guaranteed inbounds of the accessed object.
+static bool evaluateAddRecAtMaxBTCWillNotWrap(const SCEVAddRecExpr *AR,
+                                              const SCEV *MaxBTC,
+                                              ScalarEvolution &SE,
+                                              const DataLayout &DL) {
+  auto *PointerBase = SE.getPointerBase(AR->getStart());
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david-arm wrote:

This assumes `AR` is for pointers, but the function name indicates the add rec could be anything. Is it worth making that clear in the function name? I'm not sure what would happen if we call `SE.getPointerBase` for something that isn't a pointer?

https://github.com/llvm/llvm-project/pull/128061