ms-inline-asm: Scope inline asm labels to functions

Summary:
This fixes PR20023.  In order to implement this scoping rule, we piggy
back on the existing LabelDecl machinery, by creating LabelDecl's that
will carry the "internal" name of the inline assembly label, which we
will rewrite the asm label to.

Reviewers: rnk

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D4589

llvm-svn: 218230

7 files changed, 87 insertions, 11 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index cc7c11ca6ef..aec7059490c 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -3709,6 +3709,13 @@ LabelDecl *LabelDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
                                SourceLocation());
 }
 
+void LabelDecl::setMSAsmLabel(StringRef Name) {
+  char *Buffer = new (getASTContext(), 1) char[Name.size() + 1];
+  memcpy(Buffer, Name.data(), Name.size());
+  Buffer[Name.size()] = '\0';
+  MSAsmName = Buffer;
+}
+
 void ValueDecl::anchor() { }
 
 bool ValueDecl::isWeak() const {
diff --git a/clang/lib/Parse/ParseStmtAsm.cpp b/clang/lib/Parse/ParseStmtAsm.cpp
index be3d79e2231..35e2e6294f8 100644
--- a/clang/lib/Parse/ParseStmtAsm.cpp
+++ b/clang/lib/Parse/ParseStmtAsm.cpp
@@ -93,6 +93,15 @@ public:
     return Info.OpDecl;
   }
 
+  StringRef LookupInlineAsmLabel(StringRef Identifier, llvm::SourceMgr &LSM,
+                                 llvm::SMLoc Location,
+                                 bool Create) override {
+    SourceLocation Loc = translateLocation(LSM, Location);
+    LabelDecl *Label =
+      TheParser.getActions().GetOrCreateMSAsmLabel(Identifier, Loc, Create);
+    return Label->getMSAsmLabel();
+  }
+
   bool LookupInlineAsmField(StringRef Base, StringRef Member,
                             unsigned &Offset) override {
     return TheParser.getActions().LookupInlineAsmField(Base, Member, Offset,
@@ -133,14 +142,13 @@ private:
     }
   }
 
-  void handleDiagnostic(const llvm::SMDiagnostic &D) {
+  SourceLocation translateLocation(const llvm::SourceMgr &LSM, llvm::SMLoc SMLoc) {
     // Compute an offset into the inline asm buffer.
     // FIXME: This isn't right if .macro is involved (but hopefully, no
     // real-world code does that).
-    const llvm::SourceMgr &LSM = *D.getSourceMgr();
     const llvm::MemoryBuffer *LBuf =
-        LSM.getMemoryBuffer(LSM.FindBufferContainingLoc(D.getLoc()));
-    unsigned Offset = D.getLoc().getPointer() - LBuf->getBufferStart();
+        LSM.getMemoryBuffer(LSM.FindBufferContainingLoc(SMLoc));
+    unsigned Offset = SMLoc.getPointer() - LBuf->getBufferStart();
 
     // Figure out which token that offset points into.
     const unsigned *TokOffsetPtr =
@@ -157,6 +165,12 @@ private:
       Loc = Tok.getLocation();
       Loc = Loc.getLocWithOffset(Offset - TokOffset);
     }
+    return Loc;
+  }
+
+  void handleDiagnostic(const llvm::SMDiagnostic &D) {
+    const llvm::SourceMgr &LSM = *D.getSourceMgr();
+    SourceLocation Loc = translateLocation(LSM, D.getLoc());
     TheParser.Diag(Loc, diag::err_inline_ms_asm_parsing) << D.getMessage();
   }
 };
diff --git a/clang/lib/Sema/JumpDiagnostics.cpp b/clang/lib/Sema/JumpDiagnostics.cpp
index 255845282df..fd75c02bb1e 100644
--- a/clang/lib/Sema/JumpDiagnostics.cpp
+++ b/clang/lib/Sema/JumpDiagnostics.cpp
@@ -84,6 +84,7 @@ private:
   void CheckJump(Stmt *From, Stmt *To, SourceLocation DiagLoc,
                  unsigned JumpDiag, unsigned JumpDiagWarning,
                  unsigned JumpDiagCXX98Compat);
+  void CheckGotoStmt(GotoStmt *GS);
 
   unsigned GetDeepestCommonScope(unsigned A, unsigned B);
 };
@@ -489,10 +490,14 @@ void JumpScopeChecker::VerifyJumps() {
 
     // With a goto,
     if (GotoStmt *GS = dyn_cast<GotoStmt>(Jump)) {
-      CheckJump(GS, GS->getLabel()->getStmt(), GS->getGotoLoc(),
-                diag::err_goto_into_protected_scope,
-                diag::ext_goto_into_protected_scope,
-                diag::warn_cxx98_compat_goto_into_protected_scope);
+      // The label may not have a statement if it's coming from inline MS ASM.
+      if (GS->getLabel()->getStmt()) {
+        CheckJump(GS, GS->getLabel()->getStmt(), GS->getGotoLoc(),
+                  diag::err_goto_into_protected_scope,
+                  diag::ext_goto_into_protected_scope,
+                  diag::warn_cxx98_compat_goto_into_protected_scope);
+      }
+      CheckGotoStmt(GS);
       continue;
     }
 
@@ -789,6 +794,15 @@ void JumpScopeChecker::CheckJump(Stmt *From, Stmt *To, SourceLocation DiagLoc,
   }
 }
 
+void JumpScopeChecker::CheckGotoStmt(GotoStmt *GS) {
+  if (GS->getLabel()->isMSAsmLabel()) {
+    S.Diag(GS->getGotoLoc(), diag::err_goto_ms_asm_label)
+        << GS->getLabel()->getIdentifier();
+    S.Diag(GS->getLabel()->getLocation(), diag::note_goto_ms_asm_label)
+        << GS->getLabel()->getIdentifier();
+  }
+}
+
 void Sema::DiagnoseInvalidJumps(Stmt *Body) {
   (void)JumpScopeChecker(Body, *this);
 }
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 69a4356b450..7ecd41697d6 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -98,6 +98,7 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
     InitDictionaryWithObjectsMethod(nullptr),
     ArrayAllocObjectsMethod(nullptr),
     DictAllocObjectsMethod(nullptr),
+    MSAsmLabelNameCounter(0),
     GlobalNewDeleteDeclared(false),
     TUKind(TUKind),
     NumSFINAEErrors(0),
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 535e33a2b6e..ae79720e383 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -1517,8 +1517,14 @@ void Sema::DiagnoseUnusedDecl(const NamedDecl *D) {
 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() == nullptr)
+  // definitions are indicated with a null substmt which is also not a resolved
+  // MS inline assembly label name.
+  bool Diagnose = false;
+  if (L->isMSAsmLabel())
+    Diagnose = !L->isResolvedMSAsmLabel();
+  else
+    Diagnose = L->getStmt() == nullptr;
+  if (Diagnose)
     S.Diag(L->getLocation(), diag::err_undeclared_label_use) <<L->getDeclName();
 }
 
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 8d2a3258b10..464206eafe3 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -432,7 +432,11 @@ Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
   TheDecl->setStmt(LS);
   if (!TheDecl->isGnuLocal()) {
     TheDecl->setLocStart(IdentLoc);
-    TheDecl->setLocation(IdentLoc);
+    if (!TheDecl->isMSAsmLabel()) {
+      // Don't update the location of MS ASM labels.  These will result in
+      // a diagnostic, and changing the location here will mess that up.
+      TheDecl->setLocation(IdentLoc);
+    }
   }
   return LS;
 }
diff --git a/clang/lib/Sema/SemaStmtAsm.cpp b/clang/lib/Sema/SemaStmtAsm.cpp
index 5aa1a2c86a9..dc50e87b589 100644
--- a/clang/lib/Sema/SemaStmtAsm.cpp
+++ b/clang/lib/Sema/SemaStmtAsm.cpp
@@ -15,6 +15,7 @@
 #include "clang/AST/RecordLayout.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/TargetInfo.h"
+#include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Scope.h"
@@ -520,6 +521,7 @@ StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
                                 ArrayRef<Expr*> Exprs,
                                 SourceLocation EndLoc) {
   bool IsSimple = (NumOutputs != 0 || NumInputs != 0);
+  getCurFunction()->setHasBranchProtectedScope();
   MSAsmStmt *NS =
     new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple,
                             /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs,
@@ -527,3 +529,31 @@ StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
                             Clobbers, EndLoc);
   return NS;
 }
+
+LabelDecl *Sema::GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
+                                       SourceLocation Location,
+                                       bool AlwaysCreate) {
+  LabelDecl* Label = LookupOrCreateLabel(PP.getIdentifierInfo(ExternalLabelName),
+                                         Location);
+
+  if (!Label->isMSAsmLabel()) {
+    // Otherwise, insert it, but only resolve it if we have seen the label itself.
+    std::string InternalName;
+    llvm::raw_string_ostream OS(InternalName);
+    // Create an internal name for the label.  The name should not be a valid mangled
+    // name, and should be unique.  We use a dot to make the name an invalid mangled
+    // name.
+    OS << "__MSASMLABEL_." << MSAsmLabelNameCounter++ << "__" << ExternalLabelName;
+    Label->setMSAsmLabel(OS.str());
+  }
+  if (AlwaysCreate) {
+    // The label might have been created implicitly from a previously encountered
+    // goto statement.  So, for both newly created and looked up labels, we mark
+    // them as resolved.
+    Label->setMSAsmLabelResolved();
+  }
+  // Adjust their location for being able to generate accurate diagnostics.
+  Label->setLocation(Location);
+
+  return Label;
+}