[clang][bytecode] Propagate IsVolatile bit to subobjects (#137293)

For
```c++
  struct S {
    constexpr S(int=0) : i(1) {}
    int i;
  };
  constexpr volatile S vs;
```

reading from `vs.i` is not allowed, even though `i` is not volatile
qualified. Propagate the IsVolatile bit down the hierarchy, so we know
reading from `vs.i` is a volatile read.

1 files changed, 7 insertions, 0 deletions

diff --git a/clang/lib/AST/ByteCode/Pointer.h b/clang/lib/AST/ByteCode/Pointer.h
index e168154..5e7c5d6 100644
--- a/clang/lib/AST/ByteCode/Pointer.h
+++ b/clang/lib/AST/ByteCode/Pointer.h
@@ -577,6 +577,13 @@ public:
     return isRoot() ? getDeclDesc()->IsConst : getInlineDesc()->IsConst;
   }
 
+  /// Checks if an object or a subfield is volatile.
+  bool isVolatile() const {
+    if (!isBlockPointer())
+      return false;
+    return isRoot() ? getDeclDesc()->IsVolatile : getInlineDesc()->IsVolatile;
+  }
+
   /// Returns the declaration ID.
   std::optional<unsigned> getDeclID() const {
     if (isBlockPointer()) {