[clang][bytecode][NFC] Add Block::getBlockDesc<T>() (#172218)

Which returns the block-level descriptor. This way we don't have to do
the reinterpret_cast dance everywhere.

Author: tbaederr

clang/lib/AST/ByteCode/Compiler.cpp

@@ -4798,8 +4798,7 @@ VarCreationState Compiler<Emitter>::visitDecl(const VarDecl *VD,
   if (!R && Context::shouldBeGloballyIndexed(VD)) {
     if (auto GlobalIndex = P.getGlobal(VD)) {
       Block *GlobalBlock = P.getGlobal(*GlobalIndex);
-      GlobalInlineDescriptor &GD =
-          *reinterpret_cast<GlobalInlineDescriptor *>(GlobalBlock->rawData());
+      auto &GD = GlobalBlock->getBlockDesc<GlobalInlineDescriptor>();
 
       GD.InitState = GlobalInitState::InitializerFailed;
       GlobalBlock->invokeDtor();
@@ -4860,8 +4859,7 @@ bool Compiler<Emitter>::visitDeclAndReturn(const VarDecl *VD, const Expr *Init,
       auto GlobalIndex = P.getGlobal(VD);
       assert(GlobalIndex);
       Block *GlobalBlock = P.getGlobal(*GlobalIndex);
-      GlobalInlineDescriptor &GD =
-          *reinterpret_cast<GlobalInlineDescriptor *>(GlobalBlock->rawData());
+      auto &GD = GlobalBlock->getBlockDesc<GlobalInlineDescriptor>();
 
       GD.InitState = GlobalInitState::InitializerFailed;
       GlobalBlock->invokeDtor();

clang/lib/AST/ByteCode/EvalEmitter.cpp

@@ -110,7 +110,7 @@ Scope::Local EvalEmitter::createLocal(Descriptor *D) {
   B->invokeCtor();
 
   // Initialize local variable inline descriptor.
-  InlineDescriptor &Desc = *reinterpret_cast<InlineDescriptor *>(B->rawData());
+  auto &Desc = B->getBlockDesc<InlineDescriptor>();
   Desc.Desc = D;
   Desc.Offset = sizeof(InlineDescriptor);
   Desc.IsActive = false;
@@ -304,7 +304,7 @@ bool EvalEmitter::emitSetLocal(uint32_t I, SourceInfo Info) {
 
   Block *B = getLocal(I);
   *reinterpret_cast<T *>(B->data()) = S.Stk.pop<T>();
-  InlineDescriptor &Desc = *reinterpret_cast<InlineDescriptor *>(B->rawData());
+  auto &Desc = B->getBlockDesc<InlineDescriptor>();
   Desc.IsInitialized = true;
 
   return true;
@@ -327,8 +327,7 @@ bool EvalEmitter::emitGetLocalEnabled(uint32_t I, SourceInfo Info) {
     return true;
 
   Block *B = getLocal(I);
-  const InlineDescriptor &Desc =
-      *reinterpret_cast<InlineDescriptor *>(B->rawData());
+  const auto &Desc = B->getBlockDesc<InlineDescriptor>();
 
   S.Stk.push<bool>(Desc.IsActive);
   return true;
@@ -344,7 +343,7 @@ bool EvalEmitter::emitEnableLocal(uint32_t I, SourceInfo Info) {
   // probably use a different struct than InlineDescriptor for the block-level
   // inline descriptor of local varaibles.
   Block *B = getLocal(I);
-  InlineDescriptor &Desc = *reinterpret_cast<InlineDescriptor *>(B->rawData());
+  auto &Desc = B->getBlockDesc<InlineDescriptor>();
   Desc.IsActive = true;
   return true;
 }

clang/lib/AST/ByteCode/Interp.cpp

@@ -736,8 +736,7 @@ static bool CheckWeak(InterpState &S, CodePtr OpPC, const Block *B) {
 // For example, since those can't be members of structs, they also can't
 // be mutable.
 bool CheckGlobalLoad(InterpState &S, CodePtr OpPC, const Block *B) {
-  const auto &Desc =
-      *reinterpret_cast<const GlobalInlineDescriptor *>(B->rawData());
+  const auto &Desc = B->getBlockDesc<GlobalInlineDescriptor>();
   if (!B->isAccessible()) {
     if (!CheckExtern(S, OpPC, Pointer(const_cast<Block *>(B))))
       return false;

clang/lib/AST/ByteCode/Interp.h

@@ -1455,8 +1455,7 @@ bool GetGlobal(InterpState &S, CodePtr OpPC, uint32_t I) {
 template <PrimType Name, class T = typename PrimConv<Name>::T>
 bool GetGlobalUnchecked(InterpState &S, CodePtr OpPC, uint32_t I) {
   const Block *B = S.P.getGlobal(I);
-  const auto &Desc =
-      *reinterpret_cast<const GlobalInlineDescriptor *>(B->rawData());
+  const auto &Desc = B->getBlockDesc<GlobalInlineDescriptor>();
   if (Desc.InitState != GlobalInitState::Initialized)
     return DiagnoseUninitialized(S, OpPC, B->isExtern(), B->getDescriptor(),
                                  AK_Read);

clang/lib/AST/ByteCode/InterpBlock.h

@@ -122,6 +122,14 @@ class Block final {
   }
   template <typename T> T &deref() { return *reinterpret_cast<T *>(data()); }
 
+  template <typename T> T &getBlockDesc() {
+    assert(sizeof(T) == getDescriptor()->getMetadataSize());
+    return *reinterpret_cast<T *>(rawData());
+  }
+  template <typename T> const T &getBlockDesc() const {
+    return const_cast<Block *>(this)->getBlockDesc<T>();
+  }
+
   /// Invokes the constructor.
   void invokeCtor() {
     assert(!IsInitialized);

clang/lib/AST/ByteCode/Pointer.cpp

@@ -444,8 +444,7 @@ bool Pointer::isInitialized() const {
 
   if (isRoot() && BS.Base == sizeof(GlobalInlineDescriptor) &&
       Offset == BS.Base) {
-    const GlobalInlineDescriptor &GD =
-        *reinterpret_cast<const GlobalInlineDescriptor *>(block()->rawData());
+    const auto &GD = block()->getBlockDesc<GlobalInlineDescriptor>();
     return GD.InitState == GlobalInitState::Initialized;
   }
 
@@ -473,8 +472,7 @@ bool Pointer::isElementInitialized(unsigned Index) const {
 
   if (isRoot() && BS.Base == sizeof(GlobalInlineDescriptor) &&
       Offset == BS.Base) {
-    const GlobalInlineDescriptor &GD =
-        *reinterpret_cast<const GlobalInlineDescriptor *>(block()->rawData());
+    const auto &GD = block()->getBlockDesc<GlobalInlineDescriptor>();
     return GD.InitState == GlobalInitState::Initialized;
   }
 
@@ -499,8 +497,7 @@ void Pointer::initialize() const {
 
   if (isRoot() && BS.Base == sizeof(GlobalInlineDescriptor) &&
       Offset == BS.Base) {
-    GlobalInlineDescriptor &GD = *reinterpret_cast<GlobalInlineDescriptor *>(
-        asBlockPointer().Pointee->rawData());
+    auto &GD = BS.Pointee->getBlockDesc<GlobalInlineDescriptor>();
     GD.InitState = GlobalInitState::Initialized;
     return;
   }
@@ -565,8 +562,7 @@ bool Pointer::allElementsInitialized() const {
 
   if (isRoot() && BS.Base == sizeof(GlobalInlineDescriptor) &&
       Offset == BS.Base) {
-    const GlobalInlineDescriptor &GD =
-        *reinterpret_cast<const GlobalInlineDescriptor *>(block()->rawData());
+    const auto &GD = block()->getBlockDesc<GlobalInlineDescriptor>();
     return GD.InitState == GlobalInitState::Initialized;
   }