[llvm] [BasicAA] Track nuw through decomposed expressions (PR #106512)

[Nikita Popov via llvm-commits]

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@@ -375,24 +375,28 @@ struct LinearExpression {
   APInt Scale;
   APInt Offset;
 
+  /// True if all operations in this expression are NUW.
+  bool IsNUW;
   /// True if all operations in this expression are NSW.
   bool IsNSW;
 
   LinearExpression(const CastedValue &Val, const APInt &Scale,
-                   const APInt &Offset, bool IsNSW)
-      : Val(Val), Scale(Scale), Offset(Offset), IsNSW(IsNSW) {}
+                   const APInt &Offset, bool IsNUW, bool IsNSW)
+      : Val(Val), Scale(Scale), Offset(Offset), IsNUW(IsNUW), IsNSW(IsNSW) {}
 
-  LinearExpression(const CastedValue &Val) : Val(Val), IsNSW(true) {
+  LinearExpression(const CastedValue &Val)
+      : Val(Val), IsNUW(true), IsNSW(true) {
     unsigned BitWidth = Val.getBitWidth();
     Scale = APInt(BitWidth, 1);
     Offset = APInt(BitWidth, 0);
   }
 
-  LinearExpression mul(const APInt &Other, bool MulIsNSW) const {
+  LinearExpression mul(const APInt &Other, bool MulIsNUW, bool MulIsNSW) const {
     // The check for zero offset is necessary, because generally
     // (X +nsw Y) *nsw Z does not imply (X *nsw Z) +nsw (Y *nsw Z).
     bool NSW = IsNSW && (Other.isOne() || (MulIsNSW && Offset.isZero()));
-    return LinearExpression(Val, Scale * Other, Offset * Other, NSW);
+    bool NUW = IsNUW && (Other.isOne() || MulIsNUW);
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nikic wrote:

Proof that mul nuw always distributes (unlike mul nsw): https://alive2.llvm.org/ce/z/MZd_JJ

https://github.com/llvm/llvm-project/pull/106512