[clang][bytecode] Add lifetime information for primitive array elements

clang/lib/AST/ByteCode/Descriptor.h

@@ -275,7 +275,6 @@ struct Descriptor final {
   void dump(llvm::raw_ostream &OS) const;
   void dumpFull(unsigned Offset = 0, unsigned Indent = 0) const;
 };
-
 } // namespace interp
 } // namespace clang
 

clang/lib/AST/ByteCode/InitMap.cpp

@@ -10,9 +10,6 @@
 using namespace clang;
 using namespace clang::interp;
 
-InitMap::InitMap(unsigned N)
-    : UninitFields(N), Data(std::make_unique<T[]>(numFields(N))) {}
-
 bool InitMap::initializeElement(unsigned I) {
   unsigned Bucket = I / PER_FIELD;
   T Mask = T(1) << (I % PER_FIELD);
@@ -29,3 +26,29 @@ bool InitMap::isElementInitialized(unsigned I) const {
   unsigned Bucket = I / PER_FIELD;
   return data()[Bucket] & (T(1) << (I % PER_FIELD));
 }
+
+// Values in the second half of data() are inverted,
+// i.e. 0 means "lifetime started".
+void InitMap::startElementLifetime(unsigned I) {
+  unsigned LifetimeIndex = NumElems + I;
+
+  unsigned Bucket = LifetimeIndex / PER_FIELD;
+  T Mask = T(1) << (LifetimeIndex % PER_FIELD);
+  if ((data()[Bucket] & Mask)) {
+    data()[Bucket] &= ~Mask;
+    --DeadFields;
+  }
+}
+
+// Values in the second half of data() are inverted,
+// i.e. 0 means "lifetime started".
+void InitMap::endElementLifetime(unsigned I) {
+  unsigned LifetimeIndex = NumElems + I;
+
+  unsigned Bucket = LifetimeIndex / PER_FIELD;
+  T Mask = T(1) << (LifetimeIndex % PER_FIELD);
+  if (!(data()[Bucket] & Mask)) {
+    data()[Bucket] |= Mask;
+    ++DeadFields;
+  }
+}

clang/lib/AST/ByteCode/InitMap.h

@@ -24,27 +24,44 @@ struct InitMap final {
   using T = uint64_t;
   /// Bits stored in a single field.
   static constexpr uint64_t PER_FIELD = sizeof(T) * CHAR_BIT;
+  /// Number of fields in the init map.
+  unsigned NumElems;
   /// Number of fields not initialized.
   unsigned UninitFields;
+  unsigned DeadFields = 0;
   std::unique_ptr<T[]> Data;
 
 public:
   /// Initializes the map with no fields set.
-  explicit InitMap(unsigned N);
-
-private:
-  friend class Pointer;
+  explicit InitMap(unsigned N)
+      : NumElems(N), UninitFields(N),
+        Data(std::make_unique<T[]>(numFields(N))) {}
+  explicit InitMap(unsigned N, bool AllInitialized)
+      : NumElems(N), UninitFields(AllInitialized ? 0 : N),
+        Data(std::make_unique<T[]>(numFields(N))) {}
+
+  void startElementLifetime(unsigned I);
+  void endElementLifetime(unsigned I);
+
+  bool isElementAlive(unsigned I) const {
+    unsigned LifetimeIndex = NumElems + I;
+    unsigned Bucket = LifetimeIndex / PER_FIELD;
+    return !(data()[Bucket] & (T(1) << (LifetimeIndex % PER_FIELD)));
+  }
 
-  /// Returns a pointer to storage.
-  T *data() { return Data.get(); }
-  const T *data() const { return Data.get(); }
+  bool allElementsAlive() const { return DeadFields == 0; }
 
   /// Initializes an element. Returns true when object if fully initialized.
   bool initializeElement(unsigned I);
 
   /// Checks if an element was initialized.
   bool isElementInitialized(unsigned I) const;
 
+private:
+  /// Returns a pointer to storage.
+  T *data() { return Data.get(); }
+  const T *data() const { return Data.get(); }
+
   static constexpr size_t numFields(unsigned N) {
     return ((N + PER_FIELD - 1) / PER_FIELD) * 2;
   }
@@ -94,7 +111,6 @@ struct InitMapPtr final {
   };
 };
 static_assert(sizeof(InitMapPtr) == sizeof(void *));
-
 } // namespace interp
 } // namespace clang
 

clang/lib/AST/ByteCode/Interp.cpp

@@ -1907,10 +1907,6 @@ bool EndLifetime(InterpState &S, CodePtr OpPC) {
   if (Ptr.isBlockPointer() && !CheckDummy(S, OpPC, Ptr.block(), AK_Destroy))
     return false;
 
-  // FIXME: We need per-element lifetime information for primitive arrays.
-  if (Ptr.isArrayElement())
-    return true;
-
   endLifetimeRecurse(Ptr.narrow());
   return true;
 }
@@ -1921,10 +1917,6 @@ bool EndLifetimePop(InterpState &S, CodePtr OpPC) {
   if (Ptr.isBlockPointer() && !CheckDummy(S, OpPC, Ptr.block(), AK_Destroy))
     return false;
 
-  // FIXME: We need per-element lifetime information for primitive arrays.
-  if (Ptr.isArrayElement())
-    return true;
-
   endLifetimeRecurse(Ptr.narrow());
   return true;
 }
@@ -2324,6 +2316,34 @@ bool FinishInitGlobal(InterpState &S, CodePtr OpPC) {
   return true;
 }
 
+bool Destroy(InterpState &S, CodePtr OpPC, uint32_t I) {
+  assert(S.Current->getFunction());
+  // FIXME: We iterate the scope once here and then again in the destroy() call
+  // below.
+  for (auto &Local : S.Current->getFunction()->getScope(I).locals_reverse()) {
+    if (!S.Current->getLocalBlock(Local.Offset)->isInitialized())
+      continue;
+    const Pointer &Ptr = S.Current->getLocalPointer(Local.Offset);
+    if (Ptr.getLifetime() == Lifetime::Ended) {
+      // Try to use the declaration for better diagnostics
+      if (const Decl *D = Ptr.getDeclDesc()->asDecl()) {
+        auto *ND = cast<NamedDecl>(D);
+        S.FFDiag(ND->getLocation(),
+                 diag::note_constexpr_destroy_out_of_lifetime)
+            << ND->getNameAsString();
+      } else {
+        S.FFDiag(Ptr.getDeclDesc()->getLocation(),
+                 diag::note_constexpr_destroy_out_of_lifetime)
+            << Ptr.toDiagnosticString(S.getASTContext());
+      }
+      return false;
+    }
+  }
+
+  S.Current->destroy(I);
+  return true;
+}
+
 // https://github.com/llvm/llvm-project/issues/102513
 #if defined(_MSC_VER) && !defined(__clang__) && !defined(NDEBUG)
 #pragma optimize("", off)

clang/lib/AST/ByteCode/Interp.h

@@ -122,6 +122,7 @@ bool CheckFunctionDecl(InterpState &S, CodePtr OpPC, const FunctionDecl *FD);
 bool handleFixedPointOverflow(InterpState &S, CodePtr OpPC,
                               const FixedPoint &FP);
 
+bool Destroy(InterpState &S, CodePtr OpPC, uint32_t I);
 bool isConstexprUnknown(const Pointer &P);
 
 enum class ShiftDir { Left, Right };
@@ -2436,38 +2437,6 @@ inline bool SubPtr(InterpState &S, CodePtr OpPC, bool ElemSizeIsZero) {
   return true;
 }
 
-//===----------------------------------------------------------------------===//
-// Destroy
-//===----------------------------------------------------------------------===//
-
-inline bool Destroy(InterpState &S, CodePtr OpPC, uint32_t I) {
-  assert(S.Current->getFunction());
-
-  // FIXME: We iterate the scope once here and then again in the destroy() call
-  // below.
-  for (auto &Local : S.Current->getFunction()->getScope(I).locals_reverse()) {
-    const Pointer &Ptr = S.Current->getLocalPointer(Local.Offset);
-
-    if (Ptr.getLifetime() == Lifetime::Ended) {
-      // Try to use the declaration for better diagnostics
-      if (const Decl *D = Ptr.getDeclDesc()->asDecl()) {
-        auto *ND = cast<NamedDecl>(D);
-        S.FFDiag(ND->getLocation(),
-                 diag::note_constexpr_destroy_out_of_lifetime)
-            << ND->getNameAsString();
-      } else {
-        S.FFDiag(Ptr.getDeclDesc()->getLocation(),
-                 diag::note_constexpr_destroy_out_of_lifetime)
-            << Ptr.toDiagnosticString(S.getASTContext());
-      }
-      return false;
-    }
-  }
-
-  S.Current->destroy(I);
-  return true;
-}
-
 inline bool InitScope(InterpState &S, CodePtr OpPC, uint32_t I) {
   S.Current->initScope(I);
   return true;

clang/lib/AST/ByteCode/Pointer.cpp

@@ -490,6 +490,19 @@ bool Pointer::isElementInitialized(unsigned Index) const {
   return isInitialized();
 }
 
+bool Pointer::isElementAlive(unsigned Index) const {
+  assert(getFieldDesc()->isPrimitiveArray());
+
+  InitMapPtr &IM = getInitMap();
+  if (!IM.hasInitMap())
+    return true;
+
+  if (IM.allInitialized())
+    return true;
+
+  return IM->isElementAlive(Index);
+}
+
 void Pointer::initialize() const {
   if (!isBlockPointer())
     return;
@@ -524,7 +537,6 @@ void Pointer::initializeElement(unsigned Index) const {
   assert(Index < getFieldDesc()->getNumElems());
 
   InitMapPtr &IM = getInitMap();
-
   if (IM.allInitialized())
     return;
 
@@ -562,6 +574,23 @@ bool Pointer::allElementsInitialized() const {
   return IM.allInitialized();
 }
 
+bool Pointer::allElementsAlive() const {
+  assert(getFieldDesc()->isPrimitiveArray());
+  assert(isArrayRoot());
+
+  if (isStatic() && BS.Base == 0)
+    return true;
+
+  if (isRoot() && BS.Base == sizeof(GlobalInlineDescriptor) &&
+      Offset == BS.Base) {
+    const auto &GD = block()->getBlockDesc<GlobalInlineDescriptor>();
+    return GD.InitState == GlobalInitState::Initialized;
+  }
+
+  InitMapPtr &IM = getInitMap();
+  return IM.allInitialized() || (IM.hasInitMap() && IM->allElementsAlive());
+}
+
 void Pointer::activate() const {
   // Field has its bit in an inline descriptor.
   assert(BS.Base != 0 && "Only composite fields can be activated");

clang/lib/AST/ByteCode/Pointer.h

@@ -15,6 +15,7 @@
 
 #include "Descriptor.h"
 #include "FunctionPointer.h"
+#include "InitMap.h"
 #include "InterpBlock.h"
 #include "clang/AST/ComparisonCategories.h"
 #include "clang/AST/Decl.h"
@@ -721,6 +722,9 @@ class Pointer {
   /// Like isInitialized(), but for primitive arrays.
   bool isElementInitialized(unsigned Index) const;
   bool allElementsInitialized() const;
+  bool allElementsAlive() const;
+  bool isElementAlive(unsigned Index) const;
+
   /// Activats a field.
   void activate() const;
   /// Deactivates an entire strurcutre.
@@ -731,6 +735,20 @@ class Pointer {
       return Lifetime::Started;
     if (BS.Base < sizeof(InlineDescriptor))
       return Lifetime::Started;
+
+    if (inArray() && !isArrayRoot()) {
+      InitMapPtr &IM = getInitMap();
+
+      if (!IM.hasInitMap()) {
+        if (IM.allInitialized())
+          return Lifetime::Started;
+        return getArray().getLifetime();
+      }
+
+      return IM->isElementAlive(getIndex()) ? Lifetime::Started
+                                            : Lifetime::Ended;
+    }
+
     return getInlineDesc()->LifeState;
   }
 
@@ -739,6 +757,17 @@ class Pointer {
       return;
     if (BS.Base < sizeof(InlineDescriptor))
       return;
+
+    if (inArray()) {
+      const Descriptor *Desc = getFieldDesc();
+      InitMapPtr &IM = getInitMap();
+      if (!IM.hasInitMap())
+        IM.setInitMap(new InitMap(Desc->getNumElems(), IM.allInitialized()));
+
+      IM->endElementLifetime(getIndex());
+      return;
+    }
+
     getInlineDesc()->LifeState = Lifetime::Ended;
   }
 
@@ -747,6 +776,18 @@ class Pointer {
       return;
     if (BS.Base < sizeof(InlineDescriptor))
       return;
+
+    if (inArray()) {
+      InitMapPtr &IM = getInitMap();
+      if (!IM.hasInitMap()) {
+        const Descriptor *Desc = getFieldDesc();
+        IM.setInitMap(new InitMap(Desc->getNumElems(), IM.allInitialized()));
+      }
+
+      IM->startElementLifetime(getIndex());
+      return;
+    }
+
     getInlineDesc()->LifeState = Lifetime::Started;
   }
 
@@ -791,7 +832,6 @@ class Pointer {
   friend class DeadBlock;
   friend class MemberPointer;
   friend class InterpState;
-  friend struct InitMap;
   friend class DynamicAllocator;
   friend class Program;
 
@@ -838,6 +878,8 @@ inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Pointer &P) {
   OS << ' ';
   if (const Descriptor *D = P.getFieldDesc())
     D->dump(OS);
+  if (P.isArrayElement())
+    OS << " index " << P.getIndex();
   return OS;
 }
 

clang/lib/AST/CMakeLists.txt

@@ -73,6 +73,7 @@ add_clang_library(clangAST
   ByteCode/Compiler.cpp
   ByteCode/Context.cpp
   ByteCode/Descriptor.cpp
+  ByteCode/InitMap.cpp
   ByteCode/Disasm.cpp
   ByteCode/EvalEmitter.cpp
   ByteCode/Function.cpp

clang/test/AST/ByteCode/builtin-functions.cpp

@@ -1848,11 +1848,9 @@ namespace WithinLifetime {
   } xstd; // both-error {{is not a constant expression}} \
           // both-note {{in call to}}
 
-  /// FIXME: We do not have per-element lifetime information for primitive arrays.
-  /// See https://github.com/llvm/llvm-project/issues/147528
   consteval bool test_dynamic(bool read_after_deallocate) {
     std::allocator<int> a;
-    int* p = a.allocate(1); // expected-note 2{{allocation performed here was not deallocated}}
+    int* p = a.allocate(1);
     // a.allocate starts the lifetime of an array,
     // the complete object of *p has started its lifetime
     if (__builtin_is_within_lifetime(p))
@@ -1865,12 +1863,12 @@ namespace WithinLifetime {
       return false;
     a.deallocate(p, 1);
     if (read_after_deallocate)
-      __builtin_is_within_lifetime(p); // ref-note {{read of heap allocated object that has been deleted}}
+      __builtin_is_within_lifetime(p); // both-note {{read of heap allocated object that has been deleted}}
     return true;
   }
-  static_assert(test_dynamic(false)); // expected-error {{not an integral constant expression}}
+  static_assert(test_dynamic(false));
   static_assert(test_dynamic(true)); // both-error {{not an integral constant expression}} \
-                                     // ref-note {{in call to}}
+                                     // both-note {{in call to}}
 }
 
 #ifdef __SIZEOF_INT128__