[MS] Make #pragma pack use PragmaStack<> class.

Make implementation of #pragma pack consistent with other "stack" pragmas.
Use PragmaStack<> class instead of old representation of internal stack.
Don't change compiler's behavior.

TODO:
  1. Introduce diagnostics on popping named slots from pragma stacks.

Reviewer: rnk

Differential revision: http://reviews.llvm.org/D19727


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@268085 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Denis Zobnin

include/clang/Sema/Sema.h

@@ -317,10 +317,6 @@ class Sema {
   /// This is used as part of a hack to omit that class from ADL results.
   DeclarationName VAListTagName;
 
-  /// PackContext - Manages the stack for \#pragma pack. An alignment
-  /// of 0 indicates default alignment.
-  void *PackContext; // Really a "PragmaPackStack*"
-
   bool MSStructPragmaOn; // True when \#pragma ms_struct on
 
   /// \brief Controls member pointer representation format under the MS ABI.
@@ -338,6 +334,7 @@ class Sema {
     PSK_Set       = 0x1,                // #pragma (value)
     PSK_Push      = 0x2,                // #pragma (push[, id])
     PSK_Pop       = 0x4,                // #pragma (pop[, id])
+    PSK_Show      = 0x8,                // #pragma (show) -- only for "pack"!
     PSK_Push_Set  = PSK_Push | PSK_Set, // #pragma (push[, id], value)
     PSK_Pop_Set   = PSK_Pop | PSK_Set,  // #pragma (pop[, id], value)
   };
@@ -400,11 +397,15 @@ class Sema {
   /// 2: Always insert vtordisps to support RTTI on partially constructed
   ///    objects
   PragmaStack<MSVtorDispAttr::Mode> VtorDispStack;
+  // #pragma pack.
+  // Sentinel to represent when the stack is set to mac68k alignment.
+  static const unsigned kMac68kAlignmentSentinel = ~0U;
+  PragmaStack<unsigned> PackStack;
+  // Segment #pragmas.
   PragmaStack<StringLiteral *> DataSegStack;
   PragmaStack<StringLiteral *> BSSSegStack;
   PragmaStack<StringLiteral *> ConstSegStack;
   PragmaStack<StringLiteral *> CodeSegStack;
-  // TODO: Change implementation of #pragma pack to use PragmaStack<> approach.
 
   // RAII object to push / pop sentinel slots for all MS #pragma stacks.
   // Actions should be performed only if we enter / exit a C++ method body.
@@ -7658,20 +7659,9 @@ class Sema {
   void ActOnPragmaOptionsAlign(PragmaOptionsAlignKind Kind,
                                SourceLocation PragmaLoc);
 
-  enum PragmaPackKind {
-    PPK_Default, // #pragma pack([n])
-    PPK_Show,    // #pragma pack(show), only supported by MSVC.
-    PPK_Push,    // #pragma pack(push, [identifier], [n])
-    PPK_Pop      // #pragma pack(pop, [identifier], [n])
-  };
-
   /// ActOnPragmaPack - Called on well formed \#pragma pack(...).
-  void ActOnPragmaPack(PragmaPackKind Kind,
-                       IdentifierInfo *Name,
-                       Expr *Alignment,
-                       SourceLocation PragmaLoc,
-                       SourceLocation LParenLoc,
-                       SourceLocation RParenLoc);
+  void ActOnPragmaPack(SourceLocation PragmaLoc, PragmaMsStackAction Action,
+                       StringRef SlotLabel, Expr *Alignment);
 
   /// ActOnPragmaMSStruct - Called on well formed \#pragma ms_struct [on|off].
   void ActOnPragmaMSStruct(PragmaMSStructKind Kind);

lib/Parse/ParsePragma.cpp

@@ -337,11 +337,9 @@ void Parser::HandlePragmaVisibility() {
 
 namespace {
 struct PragmaPackInfo {
-  Sema::PragmaPackKind Kind;
-  IdentifierInfo *Name;
+  Sema::PragmaMsStackAction Action;
+  StringRef SlotLabel;
   Token Alignment;
-  SourceLocation LParenLoc;
-  SourceLocation RParenLoc;
 };
 } // end anonymous namespace
 
@@ -356,8 +354,8 @@ void Parser::HandlePragmaPack() {
     if (Alignment.isInvalid())
       return;
   }
-  Actions.ActOnPragmaPack(Info->Kind, Info->Name, Alignment.get(), PragmaLoc,
-                          Info->LParenLoc, Info->RParenLoc);
+  Actions.ActOnPragmaPack(PragmaLoc, Info->Action, Info->SlotLabel,
+                          Alignment.get());
 }
 
 void Parser::HandlePragmaMSStruct() {
@@ -962,11 +960,10 @@ void PragmaPackHandler::HandlePragma(Preprocessor &PP,
     return;
   }
 
-  Sema::PragmaPackKind Kind = Sema::PPK_Default;
-  IdentifierInfo *Name = nullptr;
+  Sema::PragmaMsStackAction Action = Sema::PSK_Reset;
+  StringRef SlotLabel;
   Token Alignment;
   Alignment.startToken();
-  SourceLocation LParenLoc = Tok.getLocation();
   PP.Lex(Tok);
   if (Tok.is(tok::numeric_constant)) {
     Alignment = Tok;
@@ -976,18 +973,18 @@ void PragmaPackHandler::HandlePragma(Preprocessor &PP,
     // In MSVC/gcc, #pragma pack(4) sets the alignment without affecting
     // the push/pop stack.
     // In Apple gcc, #pragma pack(4) is equivalent to #pragma pack(push, 4)
-    if (PP.getLangOpts().ApplePragmaPack)
-      Kind = Sema::PPK_Push;
+    Action =
+        PP.getLangOpts().ApplePragmaPack ? Sema::PSK_Push_Set : Sema::PSK_Set;
   } else if (Tok.is(tok::identifier)) {
     const IdentifierInfo *II = Tok.getIdentifierInfo();
     if (II->isStr("show")) {
-      Kind = Sema::PPK_Show;
+      Action = Sema::PSK_Show;
       PP.Lex(Tok);
     } else {
       if (II->isStr("push")) {
-        Kind = Sema::PPK_Push;
+        Action = Sema::PSK_Push;
       } else if (II->isStr("pop")) {
-        Kind = Sema::PPK_Pop;
+        Action = Sema::PSK_Pop;
       } else {
         PP.Diag(Tok.getLocation(), diag::warn_pragma_invalid_action) << "pack";
         return;
@@ -998,11 +995,12 @@ void PragmaPackHandler::HandlePragma(Preprocessor &PP,
         PP.Lex(Tok);
 
         if (Tok.is(tok::numeric_constant)) {
+          Action = (Sema::PragmaMsStackAction)(Action | Sema::PSK_Set);
           Alignment = Tok;
 
           PP.Lex(Tok);
         } else if (Tok.is(tok::identifier)) {
-          Name = Tok.getIdentifierInfo();
+          SlotLabel = Tok.getIdentifierInfo()->getName();
           PP.Lex(Tok);
 
           if (Tok.is(tok::comma)) {
@@ -1013,6 +1011,7 @@ void PragmaPackHandler::HandlePragma(Preprocessor &PP,
               return;
             }
 
+            Action = (Sema::PragmaMsStackAction)(Action | Sema::PSK_Set);
             Alignment = Tok;
 
             PP.Lex(Tok);
@@ -1027,7 +1026,7 @@ void PragmaPackHandler::HandlePragma(Preprocessor &PP,
     // In MSVC/gcc, #pragma pack() resets the alignment without affecting
     // the push/pop stack.
     // In Apple gcc #pragma pack() is equivalent to #pragma pack(pop).
-    Kind = Sema::PPK_Pop;
+    Action = Sema::PSK_Pop;
   }
 
   if (Tok.isNot(tok::r_paren)) {
@@ -1044,11 +1043,9 @@ void PragmaPackHandler::HandlePragma(Preprocessor &PP,
 
   PragmaPackInfo *Info =
       PP.getPreprocessorAllocator().Allocate<PragmaPackInfo>(1);
-  Info->Kind = Kind;
-  Info->Name = Name;
+  Info->Action = Action;
+  Info->SlotLabel = SlotLabel;
   Info->Alignment = Alignment;
-  Info->LParenLoc = LParenLoc;
-  Info->RParenLoc = RParenLoc;
 
   MutableArrayRef<Token> Toks(PP.getPreprocessorAllocator().Allocate<Token>(1),
                               1);

lib/Sema/Sema.cpp

@@ -79,12 +79,13 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
     Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
     CollectStats(false), CodeCompleter(CodeCompleter),
     CurContext(nullptr), OriginalLexicalContext(nullptr),
-    PackContext(nullptr), MSStructPragmaOn(false),
+    MSStructPragmaOn(false),
     MSPointerToMemberRepresentationMethod(
         LangOpts.getMSPointerToMemberRepresentationMethod()),
     VtorDispStack(MSVtorDispAttr::Mode(LangOpts.VtorDispMode)),
-    DataSegStack(nullptr), BSSSegStack(nullptr), ConstSegStack(nullptr),
-    CodeSegStack(nullptr), CurInitSeg(nullptr), VisContext(nullptr),
+    PackStack(0), DataSegStack(nullptr), BSSSegStack(nullptr),
+    ConstSegStack(nullptr), CodeSegStack(nullptr), CurInitSeg(nullptr),
+    VisContext(nullptr),
     IsBuildingRecoveryCallExpr(false),
     ExprNeedsCleanups(false), LateTemplateParser(nullptr),
     LateTemplateParserCleanup(nullptr),
@@ -252,7 +253,6 @@ void Sema::Initialize() {
 
 Sema::~Sema() {
   llvm::DeleteContainerSeconds(LateParsedTemplateMap);
-  if (PackContext) FreePackedContext();
   if (VisContext) FreeVisContext();
   // Kill all the active scopes.
   for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)