[llvm] [ConstraintElimination] Elide redundant bounds checks in canonical loops (PR #221028)

[Alina Sbirlea via llvm-commits]

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@@ -556,6 +556,15 @@ static Decomposition decompose(Value *V, const ConstraintInfo &Info,
   if (!Ty->isIntegerTy() || Ty->getIntegerBitWidth() > 64)
     return V;
 
+  if (!IsSigned) {
+    Value *PtrOp;
+    if (match(V, m_PtrToInt(m_Value(PtrOp))) &&
+        DL.getTypeSizeInBits(Ty) ==
+            DL.getIndexTypeSizeInBits(PtrOp->getType())) {
+      return decompose(PtrOp, Info, IsSigned, DL);
+    }
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alinas wrote:

Yup, confirmed this is wrong.

Tests would fold the icmp to true: https://godbolt.org/z/7dKs7h5Ts


https://github.com/llvm/llvm-project/pull/221028