Sema for Captured Statements

Add CapturedDecl to be the DeclContext for CapturedStmt, and perform semantic
analysis. Currently captures all variables by reference.

TODO: templates

Author: Ben Langmuir <ben.langmuir@intel.com>

Differential Revision: http://llvm-reviews.chandlerc.com/D433


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179618 91177308-0d34-0410-b5e6-96231b3b80d8

29 files changed, 515 insertions, 31 deletions

diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 4260ab0bb2..f7286a0388 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -3165,6 +3165,32 @@ public:
   }
 };
 
+/// \brief This represents the body of a CapturedStmt, and serves as its
+/// DeclContext.
+class CapturedDecl : public Decl, public DeclContext {
+private:
+  Stmt *Body;
+
+  explicit CapturedDecl(DeclContext *DC)
+    : Decl(Captured, DC, SourceLocation()), DeclContext(Captured) { }
+
+public:
+  static CapturedDecl *Create(ASTContext &C, DeclContext *DC);
+
+  Stmt *getBody() const { return Body; }
+  void setBody(Stmt *B) { Body = B; }
+
+  // Implement isa/cast/dyncast/etc.
+  static bool classof(const Decl *D) { return classofKind(D->getKind()); }
+  static bool classofKind(Kind K) { return K == Captured; }
+  static DeclContext *castToDeclContext(const CapturedDecl *D) {
+    return static_cast<DeclContext *>(const_cast<CapturedDecl *>(D));
+  }
+  static CapturedDecl *castFromDeclContext(const DeclContext *DC) {
+    return static_cast<CapturedDecl *>(const_cast<DeclContext *>(DC));
+  }
+};
+
 /// \brief Describes a module import declaration, which makes the contents
 /// of the named module visible in the current translation unit.
 ///
diff --git a/include/clang/AST/DeclBase.h b/include/clang/AST/DeclBase.h
index a3e69c0af2..bceb703060 100644
--- a/include/clang/AST/DeclBase.h
+++ b/include/clang/AST/DeclBase.h
@@ -1046,6 +1046,7 @@ public:
   bool isFunctionOrMethod() const {
     switch (DeclKind) {
     case Decl::Block:
+    case Decl::Captured:
     case Decl::ObjCMethod:
       return true;
     default:
diff --git a/include/clang/AST/RecursiveASTVisitor.h b/include/clang/AST/RecursiveASTVisitor.h
index 9b4e481bfd..df41b6fa5a 100644
--- a/include/clang/AST/RecursiveASTVisitor.h
+++ b/include/clang/AST/RecursiveASTVisitor.h
@@ -1228,8 +1228,9 @@ bool RecursiveASTVisitor<Derived>::TraverseDeclContextHelper(DeclContext *DC) {
   for (DeclContext::decl_iterator Child = DC->decls_begin(),
            ChildEnd = DC->decls_end();
        Child != ChildEnd; ++Child) {
-    // BlockDecls are traversed through BlockExprs.
-    if (!isa<BlockDecl>(*Child))
+    // BlockDecls and CapturedDecls are traversed through BlockExprs and
+    // CapturedStmts respectively.
+    if (!isa<BlockDecl>(*Child) && !isa<CapturedDecl>(*Child))
       TRY_TO(TraverseDecl(*Child));
   }
 
@@ -1258,6 +1259,14 @@ DEF_TRAVERSE_DECL(BlockDecl, {
     return true;
   })
 
+DEF_TRAVERSE_DECL(CapturedDecl, {
+    TRY_TO(TraverseStmt(D->getBody()));
+    // This return statement makes sure the traversal of nodes in
+    // decls_begin()/decls_end() (done in the DEF_TRAVERSE_DECL macro)
+    // is skipped - don't remove it.
+    return true;
+  })
+
 DEF_TRAVERSE_DECL(EmptyDecl, { })
 
 DEF_TRAVERSE_DECL(FileScopeAsmDecl, {
@@ -2218,7 +2227,9 @@ DEF_TRAVERSE_STMT(UnresolvedMemberExpr, {
 DEF_TRAVERSE_STMT(SEHTryStmt, {})
 DEF_TRAVERSE_STMT(SEHExceptStmt, {})
 DEF_TRAVERSE_STMT(SEHFinallyStmt,{})
-DEF_TRAVERSE_STMT(CapturedStmt, {})
+DEF_TRAVERSE_STMT(CapturedStmt, {
+  TRY_TO(TraverseDecl(S->getCapturedDecl()));
+})
 
 DEF_TRAVERSE_STMT(CXXOperatorCallExpr, { })
 DEF_TRAVERSE_STMT(OpaqueValueExpr, { })
diff --git a/include/clang/AST/Stmt.h b/include/clang/AST/Stmt.h
index c2cfaa486c..019e678620 100644
--- a/include/clang/AST/Stmt.h
+++ b/include/clang/AST/Stmt.h
@@ -31,9 +31,9 @@ namespace llvm {
 namespace clang {
   class ASTContext;
   class Attr;
+  class CapturedDecl;
   class Decl;
   class Expr;
-  class FunctionDecl;
   class IdentifierInfo;
   class LabelDecl;
   class ParmVarDecl;
@@ -1959,7 +1959,7 @@ private:
   unsigned NumCaptures;
 
   /// \brief The implicit outlined function.
-  FunctionDecl *TheFuncDecl;
+  CapturedDecl *TheCapturedDecl;
 
   /// \brief The record for captured variables, a RecordDecl or CXXRecordDecl.
   RecordDecl *TheRecordDecl;
@@ -1967,7 +1967,7 @@ private:
   /// \brief Construct a captured statement.
   CapturedStmt(Stmt *S, ArrayRef<Capture> Captures,
                ArrayRef<Expr *> CaptureInits,
-               FunctionDecl *FD, RecordDecl *RD);
+               CapturedDecl *CD, RecordDecl *RD);
 
   /// \brief Construct an empty captured statement.
   CapturedStmt(EmptyShell Empty, unsigned NumCaptures);
@@ -1982,7 +1982,7 @@ public:
   static CapturedStmt *Create(ASTContext &Context, Stmt *S,
                               ArrayRef<Capture> Captures,
                               ArrayRef<Expr *> CaptureInits,
-                              FunctionDecl *FD, RecordDecl *RD);
+                              CapturedDecl *CD, RecordDecl *RD);
 
   static CapturedStmt *CreateDeserialized(ASTContext &Context,
                                           unsigned NumCaptures);
@@ -1994,7 +1994,7 @@ public:
   }
 
   /// \brief Retrieve the outlined function declaration.
-  const FunctionDecl *getCapturedFunctionDecl() const { return TheFuncDecl; }
+  CapturedDecl *getCapturedDecl() const { return TheCapturedDecl; }
 
   /// \brief Retrieve the record declaration for captured variables.
   const RecordDecl *getCapturedRecordDecl() const { return TheRecordDecl; }
diff --git a/include/clang/Basic/DeclNodes.td b/include/clang/Basic/DeclNodes.td
index ebcd81252f..ad2afa7a57 100644
--- a/include/clang/Basic/DeclNodes.td
+++ b/include/clang/Basic/DeclNodes.td
@@ -73,6 +73,7 @@ def Friend : Decl;
 def FriendTemplate : Decl;
 def StaticAssert : Decl;
 def Block : Decl, DeclContext;
+def Captured : Decl, DeclContext;
 def ClassScopeFunctionSpecialization : Decl;
 def Import : Decl;
 def OMPThreadPrivate : Decl;
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index cfb1798def..fd9ea51df5 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -4804,6 +4804,9 @@ let CategoryName = "Lambda Issue" in {
     "here">;
 }
 
+def err_return_in_captured_stmt : Error<
+  "cannot return from %0">;
+
 def err_operator_arrow_circular : Error<
   "circular pointer delegation detected">;
 def err_pseudo_dtor_base_not_scalar : Error<
diff --git a/include/clang/Sema/ScopeInfo.h b/include/clang/Sema/ScopeInfo.h
index 2295bf437c..a48422a308 100644
--- a/include/clang/Sema/ScopeInfo.h
+++ b/include/clang/Sema/ScopeInfo.h
@@ -24,6 +24,7 @@ namespace clang {
 
 class Decl;
 class BlockDecl;
+class CapturedDecl;
 class CXXMethodDecl;
 class ObjCPropertyDecl;
 class IdentifierInfo;
@@ -73,7 +74,8 @@ protected:
   enum ScopeKind {
     SK_Function,
     SK_Block,
-    SK_Lambda
+    SK_Lambda,
+    SK_CapturedRegion
   };
   
 public:
@@ -319,7 +321,8 @@ public:
 class CapturingScopeInfo : public FunctionScopeInfo {
 public:
   enum ImplicitCaptureStyle {
-    ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block
+    ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block,
+    ImpCap_CapturedRegion
   };
 
   ImplicitCaptureStyle ImpCaptureStyle;
@@ -461,7 +464,8 @@ public:
   }
 
   static bool classof(const FunctionScopeInfo *FSI) { 
-    return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda; 
+    return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda
+                                 || FSI->Kind == SK_CapturedRegion;
   }
 };
 
@@ -492,6 +496,46 @@ public:
   }
 };
 
+/// \brief Retains information about a captured region.
+class CapturedRegionScopeInfo: public CapturingScopeInfo {
+public:
+
+  enum CapturedRegionKind {
+    CR_Default
+  };
+
+  /// \brief The CapturedDecl for this statement.
+  CapturedDecl *TheCapturedDecl;
+  /// \brief The captured record type.
+  RecordDecl *TheRecordDecl;
+  /// \brief This is the enclosing scope of the captured region.
+  Scope *TheScope;
+  /// \brief The kind of captured region.
+  CapturedRegionKind CapRegionKind;
+
+  CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD,
+                          RecordDecl *RD, CapturedRegionKind K)
+    : CapturingScopeInfo(Diag, ImpCap_CapturedRegion),
+      TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S), CapRegionKind(K)
+  {
+    Kind = SK_CapturedRegion;
+  }
+
+  virtual ~CapturedRegionScopeInfo();
+
+  /// \brief A descriptive name for the kind of captured region this is.
+  StringRef getRegionName() const {
+    switch (CapRegionKind) {
+    case CR_Default:
+      return "default captured statement";
+    }
+  }
+
+  static bool classof(const FunctionScopeInfo *FSI) {
+    return FSI->Kind == SK_CapturedRegion;
+  }
+};
+
 class LambdaScopeInfo : public CapturingScopeInfo {
 public:
   /// \brief The class that describes the lambda.
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 01e646ef4d..f95d6a4321 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -37,6 +37,7 @@
 #include "clang/Sema/LocInfoType.h"
 #include "clang/Sema/ObjCMethodList.h"
 #include "clang/Sema/Ownership.h"
+#include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/TypoCorrection.h"
 #include "clang/Sema/Weak.h"
 #include "llvm/ADT/ArrayRef.h"
@@ -65,6 +66,7 @@ namespace clang {
   class ArrayType;
   class AttributeList;
   class BlockDecl;
+  class CapturedDecl;
   class CXXBasePath;
   class CXXBasePaths;
   class CXXBindTemporaryExpr;
@@ -174,6 +176,7 @@ namespace clang {
 namespace sema {
   class AccessedEntity;
   class BlockScopeInfo;
+  class CapturedRegionScopeInfo;
   class CapturingScopeInfo;
   class CompoundScopeInfo;
   class DelayedDiagnostic;
@@ -916,6 +919,9 @@ public:
   void PushFunctionScope();
   void PushBlockScope(Scope *BlockScope, BlockDecl *Block);
   void PushLambdaScope(CXXRecordDecl *Lambda, CXXMethodDecl *CallOperator);
+  void PushCapturedRegionScope(Scope *RegionScope, CapturedDecl *CD,
+                               RecordDecl *RD,
+                               sema::CapturedRegionScopeInfo::CapturedRegionKind K);
   void PopFunctionScopeInfo(const sema::AnalysisBasedWarnings::Policy *WP =0,
                             const Decl *D = 0, const BlockExpr *blkExpr = 0);
 
@@ -936,6 +942,9 @@ public:
   /// \brief Retrieve the current lambda expression, if any.
   sema::LambdaScopeInfo *getCurLambda();
 
+  /// \brief Retrieve the current captured region, if any.
+  sema::CapturedRegionScopeInfo *getCurCapturedRegion();
+
   /// WeakTopLevelDeclDecls - access to \#pragma weak-generated Decls
   SmallVector<Decl*,2> &WeakTopLevelDecls() { return WeakTopLevelDecl; }
 
@@ -2767,6 +2776,12 @@ public:
   StmtResult ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope);
   StmtResult ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope);
 
+  void ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
+                                sema::CapturedRegionScopeInfo::CapturedRegionKind Kind);
+  StmtResult ActOnCapturedRegionEnd(Stmt *S);
+  void ActOnCapturedRegionError(bool IsInstantiation = false);
+  RecordDecl *CreateCapturedStmtRecordDecl(CapturedDecl *&CD,
+                                           SourceLocation Loc);
   const VarDecl *getCopyElisionCandidate(QualType ReturnType, Expr *E,
                                          bool AllowFunctionParameters);
 
diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 04d6a85860..9f5e8b1224 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -963,6 +963,8 @@ namespace clang {
       DECL_FILE_SCOPE_ASM,
       /// \brief A BlockDecl record.
       DECL_BLOCK,
+      /// \brief A CapturedDecl record.
+      DECL_CAPTURED,
       /// \brief A record that stores the set of declarations that are
       /// lexically stored within a given DeclContext.
       ///
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 36044826e8..d572335fb3 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -3234,6 +3234,10 @@ MSPropertyDecl *MSPropertyDecl::CreateDeserialized(ASTContext &C,
                                   0, 0);
 }
 
+CapturedDecl *CapturedDecl::Create(ASTContext &C, DeclContext *DC) {
+  return new (C) CapturedDecl(DC);
+}
+
 EnumConstantDecl *EnumConstantDecl::Create(ASTContext &C, EnumDecl *CD,
                                            SourceLocation L,
                                            IdentifierInfo *Id, QualType T,
diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 3f23f3d855..402d83683a 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -553,6 +553,7 @@ unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
     case StaticAssert:
     case ObjCPropertyImpl:
     case Block:
+    case Captured:
     case TranslationUnit:
 
     case UsingDirective:
@@ -839,6 +840,7 @@ DeclContext *DeclContext::getPrimaryContext() {
   case Decl::TranslationUnit:
   case Decl::LinkageSpec:
   case Decl::Block:
+  case Decl::Captured:
     // There is only one DeclContext for these entities.
     return this;
 
diff --git a/lib/AST/Stmt.cpp b/lib/AST/Stmt.cpp
index e120c6a1f8..2a7b170222 100644
--- a/lib/AST/Stmt.cpp
+++ b/lib/AST/Stmt.cpp
@@ -1038,12 +1038,12 @@ CapturedStmt::Capture *CapturedStmt::getStoredCaptures() const {
 
 CapturedStmt::CapturedStmt(Stmt *S, ArrayRef<Capture> Captures,
                            ArrayRef<Expr *> CaptureInits,
-                           FunctionDecl *FD,
+                           CapturedDecl *CD,
                            RecordDecl *RD)
   : Stmt(CapturedStmtClass), NumCaptures(Captures.size()),
-    TheFuncDecl(FD), TheRecordDecl(RD) {
+    TheCapturedDecl(CD), TheRecordDecl(RD) {
   assert( S && "null captured statement");
-  assert(FD && "null function declaration for captured statement");
+  assert(CD && "null captured declaration for captured statement");
   assert(RD && "null record declaration for captured statement");
 
   // Copy initialization expressions.
@@ -1061,14 +1061,14 @@ CapturedStmt::CapturedStmt(Stmt *S, ArrayRef<Capture> Captures,
 
 CapturedStmt::CapturedStmt(EmptyShell Empty, unsigned NumCaptures)
   : Stmt(CapturedStmtClass, Empty), NumCaptures(NumCaptures),
-    TheFuncDecl(0), TheRecordDecl(0) {
+    TheCapturedDecl(0), TheRecordDecl(0) {
   getStoredStmts()[NumCaptures] = 0;
 }
 
 CapturedStmt *CapturedStmt::Create(ASTContext &Context, Stmt *S,
                                    ArrayRef<Capture> Captures,
                                    ArrayRef<Expr *> CaptureInits,
-                                   FunctionDecl *FD,
+                                   CapturedDecl *CD,
                                    RecordDecl *RD) {
   // The layout is
   //
@@ -1089,7 +1089,7 @@ CapturedStmt *CapturedStmt::Create(ASTContext &Context, Stmt *S,
   }
 
   void *Mem = Context.Allocate(Size);
-  return new (Mem) CapturedStmt(S, Captures, CaptureInits, FD, RD);
+  return new (Mem) CapturedStmt(S, Captures, CaptureInits, CD, RD);
 }
 
 CapturedStmt *CapturedStmt::CreateDeserialized(ASTContext &Context,
@@ -1106,8 +1106,8 @@ CapturedStmt *CapturedStmt::CreateDeserialized(ASTContext &Context,
 }
 
 Stmt::child_range CapturedStmt::children() {
-  // Children are captured field initilizers and the statement being captured.
-  return child_range(getStoredStmts(), getStoredStmts() + NumCaptures + 1);
+  // Children are captured field initilizers.
+  return child_range(getStoredStmts(), getStoredStmts() + NumCaptures);
 }
 
 bool CapturedStmt::capturesVariable(const VarDecl *Var) const {
diff --git a/lib/AST/StmtPrinter.cpp b/lib/AST/StmtPrinter.cpp
index 469c2846a6..1b2285c794 100644
--- a/lib/AST/StmtPrinter.cpp
+++ b/lib/AST/StmtPrinter.cpp
@@ -451,7 +451,7 @@ void StmtPrinter::VisitMSAsmStmt(MSAsmStmt *Node) {
 }
 
 void StmtPrinter::VisitCapturedStmt(CapturedStmt *Node) {
-  PrintStmt(Node->getCapturedStmt());
+  PrintStmt(Node->getCapturedDecl()->getBody());
 }
 
 void StmtPrinter::VisitObjCAtTryStmt(ObjCAtTryStmt *Node) {
diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index 15bb6a6e45..173ca6cb09 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -70,6 +70,7 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
   case Decl::Friend:
   case Decl::FriendTemplate:
   case Decl::Block:
+  case Decl::Captured:
   case Decl::ClassScopeFunctionSpecialization:
     llvm_unreachable("Declaration should not be in declstmts!");
   case Decl::Function:  // void X();
diff --git a/lib/Frontend/PrintPreprocessedOutput.cpp b/lib/Frontend/PrintPreprocessedOutput.cpp
index 6734d7759b..7e1cae95d7 100644
--- a/lib/Frontend/PrintPreprocessedOutput.cpp
+++ b/lib/Frontend/PrintPreprocessedOutput.cpp
@@ -137,6 +137,7 @@ public:
                                   StringRef RelativePath,
                                   const Module *Imported);
   virtual void Ident(SourceLocation Loc, const std::string &str);
+  virtual void PragmaCaptured(SourceLocation Loc, StringRef Str);
   virtual void PragmaComment(SourceLocation Loc, const IdentifierInfo *Kind,
                              const std::string &Str);
   virtual void PragmaMessage(SourceLocation Loc, StringRef Str);
@@ -345,6 +346,15 @@ void PrintPPOutputPPCallbacks::Ident(SourceLocation Loc, const std::string &S) {
   EmittedTokensOnThisLine = true;
 }
 
+void PrintPPOutputPPCallbacks::PragmaCaptured(SourceLocation Loc,
+                                              StringRef Str) {
+  startNewLineIfNeeded();
+  MoveToLine(Loc);
+  OS << "#pragma captured";
+
+  setEmittedDirectiveOnThisLine();
+}
+
 /// MacroDefined - This hook is called whenever a macro definition is seen.
 void PrintPPOutputPPCallbacks::MacroDefined(const Token &MacroNameTok,
                                             const MacroDirective *MD) {
diff --git a/lib/Parse/ParsePragma.cpp b/lib/Parse/ParsePragma.cpp
index 038636d108..96328e2fb6 100644
--- a/lib/Parse/ParsePragma.cpp
+++ b/lib/Parse/ParsePragma.cpp
@@ -15,6 +15,7 @@
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Parse/ParseDiagnostic.h"
 #include "clang/Parse/Parser.h"
+#include "clang/Sema/Scope.h"
 using namespace clang;
 
 /// \brief Handle the annotation token produced for #pragma unused(...)
@@ -132,7 +133,21 @@ StmtResult Parser::HandlePragmaCaptured()
     return StmtError();
   }
 
-  return StmtEmpty();
+  SourceLocation Loc = Tok.getLocation();
+
+  ParseScope CapturedRegionScope(this, Scope::FnScope | Scope::DeclScope);
+  Actions.ActOnCapturedRegionStart(Loc, getCurScope(),
+                                   sema::CapturedRegionScopeInfo::CR_Default);
+
+  StmtResult R = ParseCompoundStatement();
+  CapturedRegionScope.Exit();
+
+  if (R.isInvalid()) {
+    Actions.ActOnCapturedRegionError();
+    return StmtError();
+  }
+
+  return Actions.ActOnCapturedRegionEnd(R.get());
 }
 
 namespace {
diff --git a/lib/Sema/ScopeInfo.cpp b/lib/Sema/ScopeInfo.cpp
index 4d29a34a73..2f48bec123 100644
--- a/lib/Sema/ScopeInfo.cpp
+++ b/lib/Sema/ScopeInfo.cpp
@@ -187,3 +187,4 @@ void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
 FunctionScopeInfo::~FunctionScopeInfo() { }
 BlockScopeInfo::~BlockScopeInfo() { }
 LambdaScopeInfo::~LambdaScopeInfo() { }
+CapturedRegionScopeInfo::~CapturedRegionScopeInfo() { }
diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index 6425f34ff5..203b689aa1 100644
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -802,7 +802,7 @@ DeclContext *Sema::getFunctionLevelDeclContext() {
   DeclContext *DC = CurContext;
 
   while (true) {
-    if (isa<BlockDecl>(DC) || isa<EnumDecl>(DC)) {
+    if (isa<BlockDecl>(DC) || isa<EnumDecl>(DC) || isa<CapturedDecl>(DC)) {
       DC = DC->getParent();
     } else if (isa<CXXMethodDecl>(DC) &&
                cast<CXXMethodDecl>(DC)->getOverloadedOperator() == OO_Call &&
@@ -1314,3 +1314,18 @@ IdentifierInfo *Sema::getSuperIdentifier() const {
     Ident_super = &Context.Idents.get("super");
   return Ident_super;
 }
+
+void Sema::PushCapturedRegionScope(Scope *S, CapturedDecl *CD, RecordDecl *RD,
+                                   CapturedRegionScopeInfo::CapturedRegionKind K) {
+  CapturingScopeInfo *CSI = new CapturedRegionScopeInfo(getDiagnostics(),
+                                                        S, CD, RD, K);
+  CSI->ReturnType = Context.VoidTy;
+  FunctionScopes.push_back(CSI);
+}
+
+CapturedRegionScopeInfo *Sema::getCurCapturedRegion() {
+  if (FunctionScopes.empty())
+    return 0;
+
+  return dyn_cast<CapturedRegionScopeInfo>(FunctionScopes.back());
+}
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index e96c5d40a3..cdfdc09e06 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -10851,6 +10851,34 @@ diagnoseUncapturableValueReference(Sema &S, SourceLocation loc,
   // capture.
 }
 
+/// \brief Capture the given variable in the captured region.
+static ExprResult captureInCapturedRegion(Sema &S, CapturedRegionScopeInfo *RSI,
+                                          VarDecl *Var, QualType FieldType,
+                                          QualType DeclRefType,
+                                          SourceLocation Loc,
+                                          bool RefersToEnclosingLocal) {
+  // The current implemention assumes that all variables are captured
+  // by references. Since there is no capture by copy, no expression evaluation
+  // will be needed.
+  //
+  RecordDecl *RD = RSI->TheRecordDecl;
+
+  FieldDecl *Field
+    = FieldDecl::Create(S.Context, RD, Loc, Loc, 0, FieldType,
+                        S.Context.getTrivialTypeSourceInfo(FieldType, Loc),
+                        0, false, ICIS_NoInit);
+  Field->setImplicit(true);
+  Field->setAccess(AS_private);
+  RD->addDecl(Field);
+
+  Expr *Ref = new (S.Context) DeclRefExpr(Var, RefersToEnclosingLocal,
+                                          DeclRefType, VK_LValue, Loc);
+  Var->setReferenced(true);
+  Var->setUsed(true);
+
+  return Ref;
+}
+
 /// \brief Capture the given variable in the given lambda expression.
 static ExprResult captureInLambda(Sema &S, LambdaScopeInfo *LSI,
                                   VarDecl *Var, QualType FieldType, 
@@ -10991,10 +11019,10 @@ bool Sema::tryCaptureVariable(VarDecl *Var, SourceLocation Loc,
   bool Explicit = (Kind != TryCapture_Implicit);
   unsigned FunctionScopesIndex = FunctionScopes.size() - 1;
   do {
-    // Only block literals and lambda expressions can capture; other
-    // scopes don't work.
+    // Only block literals, captured statements, and lambda expressions can
+    // capture; other scopes don't work.
     DeclContext *ParentDC;
-    if (isa<BlockDecl>(DC))
+    if (isa<BlockDecl>(DC) || isa<CapturedDecl>(DC))
       ParentDC = DC->getParent();
     else if (isa<CXXMethodDecl>(DC) &&
              cast<CXXMethodDecl>(DC)->getOverloadedOperator() == OO_Call &&
@@ -11028,7 +11056,7 @@ bool Sema::tryCaptureVariable(VarDecl *Var, SourceLocation Loc,
     }
 
     bool IsBlock = isa<BlockScopeInfo>(CSI);
-    bool IsLambda = !IsBlock;
+    bool IsLambda = isa<LambdaScopeInfo>(CSI);
 
     // Lambdas are not allowed to capture unnamed variables
     // (e.g. anonymous unions).
@@ -11188,8 +11216,31 @@ bool Sema::tryCaptureVariable(VarDecl *Var, SourceLocation Loc,
                         SourceLocation(), CaptureType, CopyExpr);
       Nested = true;
       continue;
-    } 
-    
+    }
+
+    if (CapturedRegionScopeInfo *RSI = dyn_cast<CapturedRegionScopeInfo>(CSI)) {
+      // By default, capture variables by reference.
+      bool ByRef = true;
+      // Using an LValue reference type is consistent with Lambdas (see below).
+      CaptureType = Context.getLValueReferenceType(DeclRefType);
+
+      Expr *CopyExpr = 0;
+      if (BuildAndDiagnose) {
+        ExprResult Result = captureInCapturedRegion(*this, RSI, Var,
+                                                    CaptureType, DeclRefType,
+                                                    Loc, Nested);
+        if (!Result.isInvalid())
+          CopyExpr = Result.take();
+      }
+
+      // Actually capture the variable.
+      if (BuildAndDiagnose)
+        CSI->addCapture(Var, /*isBlock*/false, ByRef, Nested, Loc,
+                        SourceLocation(), CaptureType, CopyExpr);
+      Nested = true;
+      continue;
+    }
+
     LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(CSI);
     
     // Determine whether we are capturing by reference or by value.
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index cfc00502c4..89c1bc51c3 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -746,6 +746,7 @@ void Sema::CheckCXXThisCapture(SourceLocation Loc, bool Explicit) {
       if (CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_LambdaByref ||
           CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_LambdaByval ||
           CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_Block ||
+          CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_CapturedRegion ||
           Explicit) {
         // This closure can capture 'this'; continue looking upwards.
         NumClosures++;
@@ -778,7 +779,19 @@ void Sema::CheckCXXThisCapture(SourceLocation Loc, bool Explicit) {
       Field->setAccess(AS_private);
       Lambda->addDecl(Field);
       ThisExpr = new (Context) CXXThisExpr(Loc, ThisTy, /*isImplicit=*/true);
+    } else if (CapturedRegionScopeInfo *RSI =
+                   dyn_cast<CapturedRegionScopeInfo>(FunctionScopes[idx])) {
+      RecordDecl *RD = RSI->TheRecordDecl;
+      FieldDecl *Field
+        = FieldDecl::Create(Context, RD, Loc, Loc, 0, ThisTy,
+                            Context.getTrivialTypeSourceInfo(ThisTy, Loc),
+                            0, false, ICIS_NoInit);
+      Field->setImplicit(true);
+      Field->setAccess(AS_private);
+      RD->addDecl(Field);
+      ThisExpr = new (Context) CXXThisExpr(Loc, ThisTy, /*isImplicit*/true);
     }
+
     bool isNested = NumClosures > 1;
     CSI->addThisCapture(isNested, Loc, ThisTy, ThisExpr);
   }
diff --git a/lib/Sema/SemaLambda.cpp b/lib/Sema/SemaLambda.cpp
index 53fa6dafdd..77e6bfd086 100644
--- a/lib/Sema/SemaLambda.cpp
+++ b/lib/Sema/SemaLambda.cpp
@@ -862,6 +862,7 @@ ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
       CaptureDefault = LCD_ByCopy;
       break;
 
+    case CapturingScopeInfo::ImpCap_CapturedRegion:
     case CapturingScopeInfo::ImpCap_LambdaByref:
       CaptureDefault = LCD_ByRef;
       break;
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index b3558a548b..88237b08b2 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -2403,6 +2403,10 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
       Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr);
       return StmtError();
     }
+  } else if (CapturedRegionScopeInfo *CurRegion =
+                 dyn_cast<CapturedRegionScopeInfo>(CurCap)) {
+    Diag(ReturnLoc, diag::err_return_in_captured_stmt) << CurRegion->getRegionName();
+    return StmtError();
   } else {
     LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(CurCap);
     if (LSI->CallOperator->getType()->getAs<FunctionType>()->getNoReturnAttr()){
@@ -2914,3 +2918,110 @@ StmtResult