[llvm] [SCEV] Introduce SCEVUse, use it instead of const SCEV * (NFCI) (WIP). (PR #91961)

[Florian Hahn via llvm-commits]

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@@ -69,6 +69,99 @@ enum SCEVTypes : unsigned short;
 
 extern bool VerifySCEV;
 
+class SCEV;
+
+class SCEVUse : public PointerIntPair<const SCEV *, 2> {
+public:
+  SCEVUse() : PointerIntPair(nullptr, 0) {}
+  SCEVUse(const SCEV *S) : PointerIntPair(S, 0) {}
+  SCEVUse(const SCEV *S, int Flags) : PointerIntPair(S, Flags) {}
+
+  operator const SCEV *() const { return getPointer(); }
+  const SCEV *operator->() const { return getPointer(); }
+  const SCEV *operator->() { return getPointer(); }
+
+  void *getRawPointer() { return getOpaqueValue(); }
+
+  /// Print out the internal representation of this scalar to the specified
+  /// stream.  This should really only be used for debugging purposes.
+  void print(raw_ostream &OS) const;
+
+  /// This method is used for debugging.
+  void dump() const;
+};
+
+template <> struct PointerLikeTypeTraits<SCEVUse> {
+  static inline void *getAsVoidPointer(SCEVUse U) { return U.getOpaqueValue(); }
+  static inline SCEVUse getFromVoidPointer(void *P) {
+    SCEVUse U;
+    U.setFromOpaqueValue(P);
+    return U;
+  }
+
+  /// Note, we assume here that void* is related to raw malloc'ed memory and
+  /// that malloc returns objects at least 4-byte aligned. However, this may be
+  /// wrong, or pointers may be from something other than malloc. In this case,
+  /// you should specify a real typed pointer or avoid this template.
+  ///
+  /// All clients should use assertions to do a run-time check to ensure that
+  /// this is actually true.
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fhahn wrote:

Adjusted, thanks!

https://github.com/llvm/llvm-project/pull/91961