Switch labels over to using normal name lookup, instead of their

own weird little DenseMap.  Hey look, we now emit unused label
warnings deterministically, amazing.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@125813 91177308-0d34-0410-b5e6-96231b3b80d8

11 files changed, 72 insertions, 151 deletions

diff --git a/include/clang/Sema/Scope.h b/include/clang/Sema/Scope.h
index ad3ad4df13..d7fda35cdb 100644
--- a/include/clang/Sema/Scope.h
+++ b/include/clang/Sema/Scope.h
@@ -53,7 +53,7 @@ public:
     /// ClassScope - The scope of a struct/union/class definition.
     ClassScope = 0x20,
 
-    /// BlockScope - This is a scope that corresponds to a block object.
+    /// BlockScope - This is a scope that corresponds to a block/closure object.
     /// Blocks serve as top-level scopes for some objects like labels, they
     /// also prevent things like break and continue.  BlockScopes always have
     /// the FnScope, BreakScope, ContinueScope, and DeclScope flags set as well.
@@ -146,8 +146,7 @@ public:
   unsigned getFlags() const { return Flags; }
   void setFlags(unsigned F) { Flags = F; }
 
-  /// isBlockScope - Return true if this scope does not correspond to a
-  /// closure.
+  /// isBlockScope - Return true if this scope correspond to a closure.
   bool isBlockScope() const { return Flags & BlockScope; }
 
   /// getParent - Return the scope that this is nested in.
diff --git a/include/clang/Sema/ScopeInfo.h b/include/clang/Sema/ScopeInfo.h
index 6a0d54d150..b0bb95509a 100644
--- a/include/clang/Sema/ScopeInfo.h
+++ b/include/clang/Sema/ScopeInfo.h
@@ -52,11 +52,6 @@ public:
   /// \brief Used to determine if errors occurred in this function or block.
   DiagnosticErrorTrap ErrorTrap;
 
-  /// LabelMap - This is a mapping from label identifiers to the LabelDecl for
-  /// it.  Forward referenced labels have a LabelDecl created for them with a
-  /// null statement.
-  llvm::DenseMap<IdentifierInfo*, LabelDecl*> LabelMap;
-
   /// SwitchStack - This is the current set of active switch statements in the
   /// block.
   llvm::SmallVector<SwitchStmt*, 8> SwitchStack;
@@ -92,11 +87,6 @@ public:
 
   virtual ~FunctionScopeInfo();
 
-  /// checkLabelUse - This checks to see if any labels are used without being
-  /// defined, emiting errors and returning true if any are found.  This also
-  /// warns about unused labels.
-  bool checkLabelUse(Stmt *Body, Sema &S);
-  
   /// \brief Clear out the information in this function scope, making it
   /// suitable for reuse.
   void Clear();
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 3bb81d4c9b..48f3e90ee1 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -1344,6 +1344,8 @@ public:
     /// Tag name lookup, which finds the names of enums, classes,
     /// structs, and unions.
     LookupTagName,
+    /// Label name lookup.
+    LookupLabel,
     /// Member name lookup, which finds the names of
     /// class/struct/union members.
     LookupMemberName,
@@ -1412,6 +1414,8 @@ public:
                                     QualType T1, QualType T2,
                                     UnresolvedSetImpl &Functions);
 
+  LabelDecl *LookupOrCreateLabel(IdentifierInfo *II, SourceLocation Loc);
+  
   DeclContextLookupResult LookupConstructors(CXXRecordDecl *Class);
   CXXDestructorDecl *LookupDestructor(CXXRecordDecl *Class);
 
@@ -1715,9 +1719,6 @@ public:
   StmtResult ActOnDefaultStmt(SourceLocation DefaultLoc,
                                       SourceLocation ColonLoc,
                                       Stmt *SubStmt, Scope *CurScope);
-  StmtResult ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
-                            SourceLocation ColonLoc, Stmt *SubStmt,
-                            AttributeList *Attr);
   StmtResult ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
                             SourceLocation ColonLoc, Stmt *SubStmt);
     
@@ -1752,9 +1753,6 @@ public:
 
   StmtResult ActOnGotoStmt(SourceLocation GotoLoc,
                            SourceLocation LabelLoc,
-                           IdentifierInfo *LabelII);
-  StmtResult ActOnGotoStmt(SourceLocation GotoLoc,
-                           SourceLocation LabelLoc,
                            LabelDecl *TheDecl);
   StmtResult ActOnIndirectGotoStmt(SourceLocation GotoLoc,
                                    SourceLocation StarLoc,
@@ -2078,11 +2076,7 @@ public:
                                 Expr *Cond, Expr *LHS, Expr *RHS);
 
   /// ActOnAddrLabel - Parse the GNU address of label extension: "&&foo".
-  ExprResult ActOnAddrLabel(SourceLocation OpLoc,
-                            SourceLocation LabLoc,
-                            IdentifierInfo *LabelII);
-  ExprResult ActOnAddrLabel(SourceLocation OpLoc,
-                            SourceLocation LabLoc,
+  ExprResult ActOnAddrLabel(SourceLocation OpLoc, SourceLocation LabLoc,
                             LabelDecl *LD);
   
   ExprResult ActOnStmtExpr(SourceLocation LPLoc, Stmt *SubStmt,
diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
index 7a6ec5923c..84d77300eb 100644
--- a/lib/Parse/ParseExpr.cpp
+++ b/lib/Parse/ParseExpr.cpp
@@ -795,8 +795,9 @@ ExprResult Parser::ParseCastExpression(bool isUnaryExpression,
       return ExprError(Diag(Tok, diag::err_expected_ident));
 
     Diag(AmpAmpLoc, diag::ext_gnu_address_of_label);
-    Res = Actions.ActOnAddrLabel(AmpAmpLoc, Tok.getLocation(),
-                                 Tok.getIdentifierInfo());
+    LabelDecl *LD = Actions.LookupOrCreateLabel(Tok.getIdentifierInfo(),
+                                                Tok.getLocation());
+    Res = Actions.ActOnAddrLabel(AmpAmpLoc, Tok.getLocation(), LD);
     ConsumeToken();
     return move(Res);
   }
diff --git a/lib/Parse/ParseStmt.cpp b/lib/Parse/ParseStmt.cpp
index 3e7ec533bd..2c4ab655ae 100644
--- a/lib/Parse/ParseStmt.cpp
+++ b/lib/Parse/ParseStmt.cpp
@@ -236,10 +236,14 @@ StmtResult Parser::ParseLabeledStatement(ParsedAttributes &attrs) {
   // Broken substmt shouldn't prevent the label from being added to the AST.
   if (SubStmt.isInvalid())
     SubStmt = Actions.ActOnNullStmt(ColonLoc);
-
-  return Actions.ActOnLabelStmt(IdentTok.getLocation(),
-                                IdentTok.getIdentifierInfo(),
-                                ColonLoc, SubStmt.get(), attrs.getList());
+  
+  LabelDecl *LD = Actions.LookupOrCreateLabel(IdentTok.getIdentifierInfo(),
+                                              IdentTok.getLocation());
+  if (AttributeList *Attrs = attrs.getList())
+    Actions.ProcessDeclAttributeList(Actions.CurScope, LD, Attrs);
+  
+  return Actions.ActOnLabelStmt(IdentTok.getLocation(), LD, ColonLoc,
+                                SubStmt.get());
 }
 
 /// ParseCaseStatement
@@ -1168,8 +1172,9 @@ StmtResult Parser::ParseGotoStatement(ParsedAttributes &attrs) {
 
   StmtResult Res;
   if (Tok.is(tok::identifier)) {
-    Res = Actions.ActOnGotoStmt(GotoLoc, Tok.getLocation(),
-                                Tok.getIdentifierInfo());
+    LabelDecl *LD = Actions.LookupOrCreateLabel(Tok.getIdentifierInfo(),
+                                                Tok.getLocation());
+    Res = Actions.ActOnGotoStmt(GotoLoc, Tok.getLocation(), LD);
     ConsumeToken();
   } else if (Tok.is(tok::star)) {
     // GNU indirect goto extension.
diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index be78024031..7eb1c57412 100644
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -45,60 +45,11 @@ void FunctionScopeInfo::Clear() {
   HasBranchIntoScope = false;
   HasIndirectGoto = false;
   
-  LabelMap.clear();
   SwitchStack.clear();
   Returns.clear();
   ErrorTrap.reset();
 }
 
-bool FunctionScopeInfo::checkLabelUse(Stmt *Body, Sema &S) {
-  bool AnyErrors = false;
-  // FIXME: The iteration order of this (and thus, the order of errors and
-  // warnings produced) is nondeterminstic.
-  for (llvm::DenseMap<IdentifierInfo*, LabelDecl*>::iterator
-       I = LabelMap.begin(), E = LabelMap.end(); I != E; ++I) {
-    LabelDecl *L = I->second;
-    
-    // Verify that we have no forward references left.  If so, there was a goto
-    // or address of a label taken, but no definition of it.  Label fwd
-    // definitions are indicated with a null substmt.
-    if (L->getStmt() != 0) {
-      S.DiagnoseUnusedDecl(L);
-      continue;
-    }
-    
-    AnyErrors = true;
-    
-    // Emit error.
-    S.Diag(L->getLocation(), diag::err_undeclared_label_use) << L->getDeclName();
-    
-    // At this point, we have gotos that use the bogus label.  Stitch it into
-    // the function body so that the AST is well formed.
-    if (Body == 0) {
-      // The whole function wasn't parsed correctly.
-      continue;
-    }
-    
-    // Otherwise, the body is valid: we want to stitch the label decl into the
-    // function somewhere so that it is properly owned and so that the goto
-    // has a valid target.  Do this by creating LabelStmt and adding it to the
-    // end of the outer CompoundStmt.
-    LabelStmt *LS = new (S.Context) LabelStmt(L->getLocation(), L, 
-                                    new (S.Context) NullStmt(L->getLocation()));
-    
-    CompoundStmt *Compound = isa<CXXTryStmt>(Body) ?
-    cast<CXXTryStmt>(Body)->getTryBlock() :
-    cast<CompoundStmt>(Body);
-    llvm::SmallVector<Stmt*, 64> Elements(Compound->body_begin(),
-                                          Compound->body_end());
-    Elements.push_back(LS);
-    Compound->setStmts(S.Context, Elements.data(), Elements.size());
-  }
-  return AnyErrors;
-}
-
-
-
 BlockScopeInfo::~BlockScopeInfo() { }
 
 void Sema::ActOnTranslationUnitScope(Scope *S) {
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 98555d9525..95ab5fadd5 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -674,6 +674,8 @@ static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
   return true;
 }
 
+/// DiagnoseUnusedDecl - Emit warnings about declarations that are not used
+/// unless they are marked attr(unused).
 void Sema::DiagnoseUnusedDecl(const NamedDecl *D) {
   if (!ShouldDiagnoseUnusedDecl(D))
     return;
@@ -689,6 +691,14 @@ void Sema::DiagnoseUnusedDecl(const NamedDecl *D) {
   Diag(D->getLocation(), DiagID) << D->getDeclName();
 }
 
+static void CheckPoppedLabel(LabelDecl *L, Sema &S) {
+  // Verify that we have no forward references left.  If so, there was a goto
+  // or address of a label taken, but no definition of it.  Label fwd
+  // definitions are indicated with a null substmt.
+  if (L->getStmt() == 0)
+    S.Diag(L->getLocation(), diag::err_undeclared_label_use) <<L->getDeclName();
+}
+
 void Sema::ActOnPopScope(SourceLocation Loc, Scope *S) {
   if (S->decl_empty()) return;
   assert((S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope)) &&
@@ -708,6 +718,10 @@ void Sema::ActOnPopScope(SourceLocation Loc, Scope *S) {
     if (!S->hasErrorOccurred())
       DiagnoseUnusedDecl(D);
     
+    // If this was a forward reference to a label, verify it was defined.
+    if (LabelDecl *LD = dyn_cast<LabelDecl>(D))
+      CheckPoppedLabel(LD, *this);
+    
     // Remove this name from our lexical scope.
     IdResolver.RemoveDecl(D);
   }
@@ -5480,11 +5494,6 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
   }
 
   // Verify and clean out per-function state.
-
-  // Check goto/label use.
-  FunctionScopeInfo *CurFn = getCurFunction();
-  CurFn->checkLabelUse(Body, *this);
-
   if (Body) {
     // C++ constructors that have function-try-blocks can't have return
     // statements in the handlers of that block. (C++ [except.handle]p14)
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 102289b032..66f6f2b960 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -1710,7 +1710,6 @@ Decl *Sema::ActOnMethodDeclaration(
   // Make sure we can establish a context for the method.
   if (!ClassDecl) {
     Diag(MethodLoc, diag::error_missing_method_context);
-    getCurFunction()->LabelMap.clear();
     return 0;
   }
   QualType resultDeclType;
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 6d339fd97c..2b1b8b2905 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1566,8 +1566,7 @@ ExprResult Sema::ActOnIdExpression(Scope *S,
       Name.getCXXNameType()->isDependentType()) {
     DependentID = true;
   } else if (SS.isSet()) {
-    DeclContext *DC = computeDeclContext(SS, false);
-    if (DC) {
+    if (DeclContext *DC = computeDeclContext(SS, false)) {
       if (RequireCompleteDeclContext(SS, DC))
         return ExprError();
     } else {
@@ -1575,10 +1574,10 @@ ExprResult Sema::ActOnIdExpression(Scope *S,
     }
   }
 
-  if (DependentID) {
+  if (DependentID)
     return ActOnDependentIdExpression(SS, NameInfo, isAddressOfOperand,
                                       TemplateArgs);
-  }
+
   bool IvarLookupFollowUp = false;
   // Perform the required lookup.
   LookupResult R(*this, NameInfo, LookupOrdinaryName);
@@ -1613,9 +1612,10 @@ ExprResult Sema::ActOnIdExpression(Scope *S,
       if (E.isInvalid())
         return ExprError();
 
-      Expr *Ex = E.takeAs<Expr>();
-      if (Ex) return Owned(Ex);
-      // Synthesize ivars lazily
+      if (Expr *Ex = E.takeAs<Expr>())
+        return Owned(Ex);
+      
+      // Synthesize ivars lazily.
       if (getLangOptions().ObjCDefaultSynthProperties &&
           getLangOptions().ObjCNonFragileABI2) {
         if (SynthesizeProvisionalIvar(*this, R, II, NameLoc)) {
@@ -8354,18 +8354,6 @@ ExprResult Sema::ActOnUnaryOp(Scope *S, SourceLocation OpLoc,
 
 /// ActOnAddrLabel - Parse the GNU address of label extension: "&&foo".
 ExprResult Sema::ActOnAddrLabel(SourceLocation OpLoc, SourceLocation LabLoc,
-                                IdentifierInfo *LabelII) {
-  // Look up the record for this label identifier.
-  LabelDecl *&TheDecl = getCurFunction()->LabelMap[LabelII];
-
-  // If we haven't seen this label yet, create a forward reference. It
-  // will be validated and/or cleaned up in ActOnFinishFunctionBody.
-  if (TheDecl == 0)
-    TheDecl = LabelDecl::Create(Context, CurContext, LabLoc, LabelII);
-  return ActOnAddrLabel(OpLoc, LabLoc, TheDecl);
-}
-
-ExprResult Sema::ActOnAddrLabel(SourceLocation OpLoc, SourceLocation LabLoc,
                                 LabelDecl *TheDecl) {
   TheDecl->setUsed();
   // Create the AST node.  The address of a label always has type 'void*'.
@@ -8866,9 +8854,6 @@ ExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
   if (getCurFunction()->NeedsScopeChecking() && !hasAnyErrorsInThisFunction())
     DiagnoseInvalidJumps(cast<CompoundStmt>(Body));
 
-  // Check goto/label use.
-  BSI->checkLabelUse(Body, *this);
-  
   BSI->TheDecl->setBody(cast<CompoundStmt>(Body));
 
   BlockExpr *Result = new (Context) BlockExpr(BSI->TheDecl, BlockTy);
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 68eccfc280..b7740bf5c0 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -210,7 +210,8 @@ static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
     IDNS = Decl::IDNS_Ordinary;
     if (CPlusPlus) {
       IDNS |= Decl::IDNS_Tag | Decl::IDNS_Member | Decl::IDNS_Namespace;
-      if (Redeclaration) IDNS |= Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend;
+      if (Redeclaration)
+        IDNS |= Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend;
     }
     break;
 
@@ -236,7 +237,10 @@ static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
       IDNS = Decl::IDNS_Tag;
     }
     break;
-
+  case Sema::LookupLabel:
+    IDNS = Decl::IDNS_Label;
+    break;
+      
   case Sema::LookupMemberName:
     IDNS = Decl::IDNS_Member;
     if (CPlusPlus)
@@ -270,8 +274,7 @@ static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
 }
 
 void LookupResult::configure() {
-  IDNS = getIDNS(LookupKind,
-                 SemaRef.getLangOptions().CPlusPlus,
+  IDNS = getIDNS(LookupKind, SemaRef.getLangOptions().CPlusPlus,
                  isForRedeclaration());
 
   // If we're looking for one of the allocation or deallocation
@@ -1059,7 +1062,6 @@ bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation) {
   if (!getLangOptions().CPlusPlus) {
     // Unqualified name lookup in C/Objective-C is purely lexical, so
     // search in the declarations attached to the name.
-
     if (NameKind == Sema::LookupRedeclarationWithLinkage) {
       // Find the nearest non-transparent declaration scope.
       while (!(S->getFlags() & Scope::DeclScope) ||
@@ -1392,6 +1394,7 @@ bool Sema::LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
     case LookupOperatorName:
     case LookupNamespaceName:
     case LookupObjCProtocolName:
+    case LookupLabel:
       // These lookups will never find a member in a C++ class (or base class).
       return false;
 
@@ -2757,9 +2760,27 @@ void Sema::LookupVisibleDecls(DeclContext *Ctx, LookupNameKind Kind,
                        /*InBaseClass=*/false, Consumer, Visited);
 }
 
-//----------------------------------------------------------------------------
+LabelDecl *Sema::LookupOrCreateLabel(IdentifierInfo *II, SourceLocation Loc) {
+  // Do a lookup to see if we have a label with this name already.
+  NamedDecl *Res = LookupSingleName(CurScope, II, Loc, LookupLabel,
+                                    NotForRedeclaration);
+  // If we found a label, check to see if it is in the same context as us.  When
+  // in a Block, we don't want to reuse a label in an enclosing function.
+  if (Res && Res->getDeclContext() != CurContext)
+    Res = 0;
+  
+  if (Res == 0) {
+    // If not forward referenced or defined already, create the backing decl.
+    Res = LabelDecl::Create(Context, CurContext, Loc, II);
+    PushOnScopeChains(Res, CurScope->getFnParent(), true);
+  }
+  
+  return cast<LabelDecl>(Res);
+}
+
+//===----------------------------------------------------------------------===//
 // Typo correction
-//----------------------------------------------------------------------------
+//===----------------------------------------------------------------------===//
 
 namespace {
 class TypoCorrectionConsumer : public VisibleDeclConsumer {
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index f31fbe2406..ba50824c1b 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -48,9 +48,8 @@ StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc, bool LeadingEmptyMacro) {
   return Owned(new (Context) NullStmt(SemiLoc, LeadingEmptyMacro));
 }
 
-StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
-                                           SourceLocation StartLoc,
-                                           SourceLocation EndLoc) {
+StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg, SourceLocation StartLoc,
+                               SourceLocation EndLoc) {
   DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
 
   // If we have an invalid decl, just return an error.
@@ -232,25 +231,6 @@ Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
 }
 
 StmtResult
-Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
-                     SourceLocation ColonLoc, Stmt *SubStmt,
-                     AttributeList *Attr) {
-  // Look up the record for this label identifier.
-  LabelDecl *&TheDecl = getCurFunction()->LabelMap[II];
-
-  // If not forward referenced or defined already, create the backing decl.
-  if (TheDecl == 0)
-    TheDecl = LabelDecl::Create(Context, CurContext, IdentLoc, II);
-
-  assert(TheDecl->getIdentifier() == II && "Label mismatch!");
-
-  if (Attr)
-    ProcessDeclAttributeList(CurScope, TheDecl, Attr);
-  
-  return ActOnLabelStmt(IdentLoc, TheDecl, ColonLoc, SubStmt);
-}
-
-StmtResult
 Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
                      SourceLocation ColonLoc, Stmt *SubStmt) {
   
@@ -1023,19 +1003,6 @@ Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
                                                    ForLoc, RParenLoc));
 }
 
-StmtResult
-Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
-                    IdentifierInfo *LabelII) {
-  // Look up the record for this label identifier.
-  LabelDecl *&TheDecl = getCurFunction()->LabelMap[LabelII];
-
-  // If we haven't seen this label yet, create a forward reference.
-  if (TheDecl == 0)
-    TheDecl = LabelDecl::Create(Context, CurContext, LabelLoc, LabelII);
-
-  return ActOnGotoStmt(GotoLoc, LabelLoc, TheDecl);
-}
-
 StmtResult Sema::ActOnGotoStmt(SourceLocation GotoLoc,
                                SourceLocation LabelLoc,
                                LabelDecl *TheDecl) {