[clang] [clang][Interp] Integral pointers (PR #84159)

[Aaron Ballman via cfe-commits]

================
@@ -26,60 +26,98 @@ Pointer::Pointer(Block *Pointee)
 Pointer::Pointer(Block *Pointee, unsigned BaseAndOffset)
     : Pointer(Pointee, BaseAndOffset, BaseAndOffset) {}
 
-Pointer::Pointer(const Pointer &P) : Pointer(P.Pointee, P.Base, P.Offset) {}
+Pointer::Pointer(const Pointer &P)
+    : Offset(P.Offset), PointeeStorage(P.PointeeStorage),
+      StorageKind(P.StorageKind) {
 
-Pointer::Pointer(Pointer &&P)
-    : Pointee(P.Pointee), Base(P.Base), Offset(P.Offset) {
-  if (Pointee)
-    Pointee->replacePointer(&P, this);
+  if (isBlockPointer() && PointeeStorage.BS.Pointee)
+    PointeeStorage.BS.Pointee->addPointer(this);
 }
 
 Pointer::Pointer(Block *Pointee, unsigned Base, unsigned Offset)
-    : Pointee(Pointee), Base(Base), Offset(Offset) {
+    : Offset(Offset), StorageKind(Storage::Block) {
   assert((Base == RootPtrMark || Base % alignof(void *) == 0) && "wrong base");
+
+  PointeeStorage.BS = {Pointee, Base};
+
   if (Pointee)
     Pointee->addPointer(this);
 }
 
+Pointer::Pointer(Pointer &&P)
+    : Offset(P.Offset), PointeeStorage(P.PointeeStorage),
+      StorageKind(P.StorageKind) {
+
+  if (StorageKind == Storage::Block && PointeeStorage.BS.Pointee) {
+    PointeeStorage.BS.Pointee->replacePointer(&P, this);
+  }
+}
+
 Pointer::~Pointer() {
-  if (Pointee) {
-    Pointee->removePointer(this);
-    Pointee->cleanup();
+  if (isIntegralPointer())
+    return;
+
+  if (PointeeStorage.BS.Pointee) {
+    PointeeStorage.BS.Pointee->removePointer(this);
+    PointeeStorage.BS.Pointee->cleanup();
   }
 }
 
 void Pointer::operator=(const Pointer &P) {
-  Block *Old = Pointee;
 
-  if (Pointee)
-    Pointee->removePointer(this);
+  if (this->isIntegralPointer() && P.isBlockPointer()) {
+  } else {
+    assert(P.StorageKind == StorageKind);
+  }
 
-  Offset = P.Offset;
-  Base = P.Base;
+  bool WasBlockPointer = isBlockPointer();
+  StorageKind = P.StorageKind;
+  if (StorageKind == Storage::Block) {
+    Block *Old = PointeeStorage.BS.Pointee;
+    if (WasBlockPointer && PointeeStorage.BS.Pointee)
+      PointeeStorage.BS.Pointee->removePointer(this);
 
-  Pointee = P.Pointee;
-  if (Pointee)
-    Pointee->addPointer(this);
+    Offset = P.Offset;
+    PointeeStorage.BS = P.PointeeStorage.BS;
+
+    if (PointeeStorage.BS.Pointee)
+      PointeeStorage.BS.Pointee->addPointer(this);
+
+    if (WasBlockPointer && Old)
+      Old->cleanup();
 
-  if (Old)
-    Old->cleanup();
+  } else if (StorageKind == Storage::Int) {
+    PointeeStorage.Int = P.PointeeStorage.Int;
+  } else
+    assert(false);
----------------
AaronBallman wrote:

```suggestion
  } else {
    assert(false);
  }
```
It would be good to add `&& "some useful message"` to this assertion.

https://github.com/llvm/llvm-project/pull/84159