1 files changed, 38 insertions, 20 deletions

diff --git a/clang/lib/AST/ByteCode/InterpBlock.h b/clang/lib/AST/ByteCode/InterpBlock.h
index 5162223..7ded1e8 100644
--- a/clang/lib/AST/ByteCode/InterpBlock.h
+++ b/clang/lib/AST/ByteCode/InterpBlock.h
@@ -42,21 +42,32 @@ enum PrimType : unsigned;
 /// the data size and the metadata size.
 ///
 class Block final {
+private:
+  static constexpr uint8_t ExternFlag = 1 << 0;
+  static constexpr uint8_t DeadFlag = 1 << 1;
+  static constexpr uint8_t WeakFlag = 1 << 2;
+  static constexpr uint8_t DummyFlag = 1 << 3;
+
 public:
   /// Creates a new block.
   Block(unsigned EvalID, const std::optional<unsigned> &DeclID,
         const Descriptor *Desc, bool IsStatic = false, bool IsExtern = false,
-        bool IsWeak = false)
-      : EvalID(EvalID), DeclID(DeclID), IsStatic(IsStatic), IsExtern(IsExtern),
-        IsDynamic(false), IsWeak(IsWeak), Desc(Desc) {
+        bool IsWeak = false, bool IsDummy = false)
+      : Desc(Desc), DeclID(DeclID), EvalID(EvalID), IsStatic(IsStatic) {
     assert(Desc);
+    AccessFlags |= (ExternFlag * IsExtern);
+    AccessFlags |= (WeakFlag * IsWeak);
+    AccessFlags |= (DummyFlag * IsDummy);
   }
 
   Block(unsigned EvalID, const Descriptor *Desc, bool IsStatic = false,
-        bool IsExtern = false, bool IsWeak = false)
-      : EvalID(EvalID), DeclID((unsigned)-1), IsStatic(IsStatic),
-        IsExtern(IsExtern), IsDynamic(false), IsWeak(IsWeak), Desc(Desc) {
+        bool IsExtern = false, bool IsWeak = false, bool IsDummy = false)
+      : Desc(Desc), DeclID((unsigned)-1), EvalID(EvalID), IsStatic(IsStatic),
+        IsDynamic(false) {
     assert(Desc);
+    AccessFlags |= (ExternFlag * IsExtern);
+    AccessFlags |= (WeakFlag * IsWeak);
+    AccessFlags |= (DummyFlag * IsDummy);
   }
 
   /// Returns the block's descriptor.
@@ -64,13 +75,15 @@ public:
   /// Checks if the block has any live pointers.
   bool hasPointers() const { return Pointers; }
   /// Checks if the block is extern.
-  bool isExtern() const { return IsExtern; }
+  bool isExtern() const { return AccessFlags & ExternFlag; }
   /// Checks if the block has static storage duration.
   bool isStatic() const { return IsStatic; }
   /// Checks if the block is temporary.
   bool isTemporary() const { return Desc->IsTemporary; }
-  bool isWeak() const { return IsWeak; }
+  bool isWeak() const { return AccessFlags & WeakFlag; }
   bool isDynamic() const { return IsDynamic; }
+  bool isDummy() const { return AccessFlags & DummyFlag; }
+  bool isDead() const { return AccessFlags & DeadFlag; }
   /// Returns the size of the block.
   unsigned getSize() const { return Desc->getAllocSize(); }
   /// Returns the declaration ID.
@@ -103,6 +116,10 @@ public:
     return reinterpret_cast<const std::byte *>(this) + sizeof(Block);
   }
 
+  template <typename T> T deref() const {
+    return *reinterpret_cast<const T *>(data());
+  }
+
   /// Invokes the constructor.
   void invokeCtor() {
     assert(!IsInitialized);
@@ -126,6 +143,8 @@ public:
   void dump() const { dump(llvm::errs()); }
   void dump(llvm::raw_ostream &OS) const;
 
+  bool isAccessible() const { return AccessFlags == 0; }
+
 private:
   friend class Pointer;
   friend class DeadBlock;
@@ -133,10 +152,13 @@ private:
   friend class DynamicAllocator;
 
   Block(unsigned EvalID, const Descriptor *Desc, bool IsExtern, bool IsStatic,
-        bool IsWeak, bool IsDead)
-      : EvalID(EvalID), IsStatic(IsStatic), IsExtern(IsExtern), IsDead(true),
-        IsDynamic(false), IsWeak(IsWeak), Desc(Desc) {
+        bool IsWeak, bool IsDummy, bool IsDead)
+      : Desc(Desc), EvalID(EvalID), IsStatic(IsStatic) {
     assert(Desc);
+    AccessFlags |= (ExternFlag * IsExtern);
+    AccessFlags |= (DeadFlag * IsDead);
+    AccessFlags |= (WeakFlag * IsWeak);
+    AccessFlags |= (DummyFlag * IsDummy);
   }
 
   /// Deletes a dead block at the end of its lifetime.
@@ -150,27 +172,23 @@ private:
   bool hasPointer(const Pointer *P) const;
 #endif
 
-  const unsigned EvalID = ~0u;
+  /// Pointer to the stack slot descriptor.
+  const Descriptor *Desc;
   /// Start of the chain of pointers.
   Pointer *Pointers = nullptr;
   /// Unique identifier of the declaration.
   std::optional<unsigned> DeclID;
+  const unsigned EvalID = ~0u;
   /// Flag indicating if the block has static storage duration.
   bool IsStatic = false;
-  /// Flag indicating if the block is an extern.
-  bool IsExtern = false;
-  /// Flag indicating if the pointer is dead. This is only ever
-  /// set once, when converting the Block to a DeadBlock.
-  bool IsDead = false;
   /// Flag indicating if the block contents have been initialized
   /// via invokeCtor.
   bool IsInitialized = false;
   /// Flag indicating if this block has been allocated via dynamic
   /// memory allocation (e.g. malloc).
   bool IsDynamic = false;
-  bool IsWeak = false;
-  /// Pointer to the stack slot descriptor.
-  const Descriptor *Desc;
+  /// AccessFlags containing IsExtern, IsDead, IsWeak, and IsDummy bits.
+  uint8_t AccessFlags = 0;
 };
 
 /// Descriptor for a dead block.