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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@218230 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/AST/Decl.h

@@ -308,6 +308,8 @@ inline raw_ostream &operator<<(raw_ostream &OS, const NamedDecl &ND) {
 class LabelDecl : public NamedDecl {
   void anchor() override;
   LabelStmt *TheStmt;
+  StringRef MSAsmName;
+  bool MSAsmNameResolved;
   /// LocStart - For normal labels, this is the same as the main declaration
   /// label, i.e., the location of the identifier; for GNU local labels,
   /// this is the location of the __label__ keyword.
@@ -315,7 +317,10 @@ class LabelDecl : public NamedDecl {
 
   LabelDecl(DeclContext *DC, SourceLocation IdentL, IdentifierInfo *II,
             LabelStmt *S, SourceLocation StartL)
-    : NamedDecl(Label, DC, IdentL, II), TheStmt(S), LocStart(StartL) {}
+    : NamedDecl(Label, DC, IdentL, II),
+      TheStmt(S),
+      MSAsmNameResolved(false),
+      LocStart(StartL) {}
 
 public:
   static LabelDecl *Create(ASTContext &C, DeclContext *DC,
@@ -335,6 +340,12 @@ public:
     return SourceRange(LocStart, getLocation());
   }
 
+  bool isMSAsmLabel() const { return MSAsmName.size() != 0; }
+  bool isResolvedMSAsmLabel() const { return isMSAsmLabel() && MSAsmNameResolved; }
+  void setMSAsmLabel(StringRef Name);
+  StringRef getMSAsmLabel() const { return MSAsmName; }
+  void setMSAsmLabelResolved() { MSAsmNameResolved = true; }
+
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K == Label; }

include/clang/Basic/DiagnosticSemaKinds.td

@@ -4133,6 +4133,10 @@ def warn_missing_braces : Warning<
 
 def err_redefinition_of_label : Error<"redefinition of label %0">;
 def err_undeclared_label_use : Error<"use of undeclared label %0">;
+def err_goto_ms_asm_label : Error<
+  "cannot jump from this goto statement to label %0 inside an inline assembly block">;
+def note_goto_ms_asm_label : Note<
+  "inline assembly label %0 declared here">;
 def warn_unused_label : Warning<"unused label %0">,
   InGroup<UnusedLabel>, DefaultIgnore;
 

include/clang/Sema/Sema.h

@@ -699,7 +699,10 @@ public:
 
   /// \brief will hold 'respondsToSelector:'
   Selector RespondsToSelectorSel;
-  
+
+  /// \brief counter for internal MS Asm label names.
+  unsigned MSAsmLabelNameCounter;
+
   /// A flag to remember whether the implicit forms of operator new and delete
   /// have been declared.
   bool GlobalNewDeleteDeclared;
@@ -3156,6 +3159,9 @@ public:
                             ArrayRef<StringRef> Clobbers,
                             ArrayRef<Expr*> Exprs,
                             SourceLocation EndLoc);
+  LabelDecl *GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
+                                   SourceLocation Location,
+                                   bool AlwaysCreate);
 
   VarDecl *BuildObjCExceptionDecl(TypeSourceInfo *TInfo, QualType ExceptionType,
                                   SourceLocation StartLoc,

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 {

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();
   }
 };

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);
 }

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),

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();
 }
 

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;
 }

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;
+}

test/CodeGen/mozilla-ms-inline-asm.c

@@ -3,6 +3,8 @@
 
 // Some test cases for MS inline asm support from Mozilla code base.
 
+void invoke_copy_to_stack() {}
+
 void invoke(void* that, unsigned methodIndex,
             unsigned paramCount, void* params)
 {
@@ -18,24 +20,25 @@ void invoke(void* that, unsigned methodIndex,
 // CHECK: call void asm sideeffect inteldialect
 // CHECK: mov edx,dword ptr $1
 // CHECK: test edx,edx
-// CHECK: jz noparams
+// CHECK: jz {{[^_]*}}__MSASMLABEL_.0__noparams
+//             ^ Can't use {{.*}} here because the matching is greedy.
 // CHECK: mov eax,edx
 // CHECK: shl eax,$$3
 // CHECK: sub esp,eax
 // CHECK: mov ecx,esp
 // CHECK: push dword ptr $0
-// CHECK: call invoke_copy_to_stack
-// CHECK: noparams:
-// CHECK: mov ecx,dword ptr $2
+// CHECK: call dword ptr $2
+// CHECK: {{.*}}__MSASMLABEL_.0__noparams:
+// CHECK: mov ecx,dword ptr $3
 // CHECK: push ecx
 // CHECK: mov edx,[ecx]
-// CHECK: mov eax,dword ptr $3
+// CHECK: mov eax,dword ptr $4
 // CHECK: call dword ptr[edx+eax*$$4]
 // CHECK: mov esp,ebp
 // CHECK: pop ebp
 // CHECK: ret
-// CHECK: "=*m,*m,*m,*m,~{eax},~{ebp},~{ecx},~{edx},~{flags},~{esp},~{dirflag},~{fpsr},~{flags}"
-// CHECK: (i8** %8, i32* %7, i8** %5, i32* %6)
+// CHECK: "=*m,*m,*m,*m,*m,~{eax},~{ebp},~{ecx},~{edx},~{flags},~{esp},~{dirflag},~{fpsr},~{flags}"
+// CHECK: (i8** %8, i32* %7, void (...)* bitcast (void ()* @invoke_copy_to_stack to void (...)*), i8** %5, i32* %6)
 // CHECK: ret void
     __asm {
         mov     edx,paramCount

test/CodeGen/ms-inline-asm.c

@@ -240,7 +240,7 @@ void t23() {
   the_label:
   }
 // CHECK: t23
-// CHECK: call void asm sideeffect inteldialect "the_label:", "~{dirflag},~{fpsr},~{flags}"()
+// CHECK: call void asm sideeffect inteldialect "{{.*}}__MSASMLABEL_.0__the_label:", "~{dirflag},~{fpsr},~{flags}"()
 }
 
 void t24_helper(void) {}
@@ -517,3 +517,30 @@ void xgetbv() {
 }
 // CHECK-LABEL: define void @xgetbv()
 // CHECK: call void asm sideeffect inteldialect "xgetbv", "~{eax},~{edx},~{dirflag},~{fpsr},~{flags}"()
+
+void label1() {
+  __asm {
+    label:
+    jmp label
+  }
+  // CHECK-LABEL: define void @label1
+  // CHECK: call void asm sideeffect inteldialect "{{.*}}__MSASMLABEL_.1__label:\0A\09jmp {{.*}}__MSASMLABEL_.1__label", "~{dirflag},~{fpsr},~{flags}"()
+}
+
+void label2() {
+  __asm {
+    jmp label
+    label:
+  }
+  // CHECK-LABEL: define void @label2
+  // CHECK: call void asm sideeffect inteldialect "jmp {{.*}}__MSASMLABEL_.2__label\0A\09{{.*}}__MSASMLABEL_.2__label:", "~{dirflag},~{fpsr},~{flags}"()
+}
+
+void label3() {
+  __asm {
+    label:
+    mov eax, label
+  }
+  // CHECK-LABEL: define void @label3
+  // CHECK: call void asm sideeffect inteldialect "{{.*}}__MSASMLABEL_.3__label:\0A\09mov eax, {{.*}}__MSASMLABEL_.3__label", "~{eax},~{dirflag},~{fpsr},~{flags}"()
+}

test/CodeGen/ms-inline-asm.cpp

@@ -122,3 +122,20 @@ void t7_using() {
   // CHECK-LABEL: define void @_Z8t7_usingv
   // CHECK: call void asm sideeffect inteldialect "mov eax, [eax].4", "~{eax},~{dirflag},~{fpsr},~{flags}"()
 }
+
+void t8() {
+  __asm some_label:
+  // CHECK-LABEL: define void @_Z2t8v()
+  // CHECK: call void asm sideeffect inteldialect "L__MSASMLABEL_.1__some_label:", "~{dirflag},~{fpsr},~{flags}"()
+  struct A {
+    static void g() {
+      __asm jmp some_label ; This should jump forwards
+      __asm some_label:
+      __asm nop
+      // CHECK-LABEL: define internal void @_ZZ2t8vEN1A1gEv()
+      // CHECK: call void asm sideeffect inteldialect "jmp L__MSASMLABEL_.2__some_label\0A\09L__MSASMLABEL_.2__some_label:\0A\09nop", "~{dirflag},~{fpsr},~{flags}"()
+    }
+  };
+  A::g();
+}
+

test/Parser/ms-inline-asm.c

@@ -48,6 +48,9 @@ void t10() {
 void t11() {
   do { __asm mov eax, 0 __asm { __asm mov edx, 1 } } while(0);
 }
+void t12() {
+  __asm jmp label // expected-error {{use of undeclared label 'label'}}
+}
 int t_fail() { // expected-note {{to match this}}
   __asm 
   __asm { // expected-error 2 {{expected}} expected-note {{to match this}}

test/Sema/ms-inline-asm.c

@@ -29,7 +29,7 @@ void f() {
   }
   f();
   __asm {
-    mov eax, TYPE bar // expected-error {{unable to lookup expression}}
+    mov eax, TYPE bar // expected-error {{unable to lookup expression}} expected-error {{use of undeclared label 'bar'}}
   }
 }
 
@@ -80,9 +80,10 @@ typedef struct {
 } A;
 
 void t3() {
-  __asm { mov eax, [eax] UndeclaredId } // expected-error {{unknown token in expression}}
+  __asm { mov eax, [eax] UndeclaredId } // expected-error {{unknown token in expression}} expected-error {{use of undeclared label 'UndeclaredId'}}
 
   // FIXME: Only emit one diagnostic here.
+  // expected-error@+3 {{use of undeclared label 'A'}}
   // expected-error@+2 {{unexpected type name 'A': expected expression}}
   // expected-error@+1 {{unknown token in expression}}
   __asm { mov eax, [eax] A }
@@ -105,7 +106,7 @@ void test_operand_size() {
 }
 
 __declspec(naked) int t5(int x) { // expected-note {{attribute is here}}
-  asm { movl eax, x } // expected-error {{parameter references not allowed in naked functions}}
+  asm { movl eax, x } // expected-error {{parameter references not allowed in naked functions}} expected-error {{use of undeclared label 'x'}}
   asm { retl }
 }
 
@@ -114,3 +115,36 @@ __declspec(naked) int t6(int x) {
   asm { mov eax, y } // No error.
   asm { ret }
 }
+
+void t7() {
+  __asm {
+    foo: // expected-note {{inline assembly label 'foo' declared here}}
+    mov eax, 0
+  }
+  goto foo; // expected-error {{cannot jump from this goto statement to label 'foo' inside an inline assembly block}}
+}
+
+void t8() {
+  __asm foo: // expected-note {{inline assembly label 'foo' declared here}}
+  __asm mov eax, 0
+  goto foo; // expected-error {{cannot jump from this goto statement to label 'foo' inside an inline assembly block}}
+}
+
+void t9() {
+  goto foo; // expected-error {{cannot jump from this goto statement to label 'foo' inside an inline assembly block}}
+  __asm {
+    foo: // expected-note {{inline assembly label 'foo' declared here}}
+    mov eax, 0
+  }
+}
+
+void t10() {
+  goto foo; // expected-error {{cannot jump from this goto statement to label 'foo' inside an inline assembly block}}
+  __asm foo: // expected-note {{inline assembly label 'foo' declared here}}
+  __asm mov eax, 0
+}
+
+void t11() {
+foo:
+  __asm mov eax, foo // expected-error {{use of undeclared label 'foo'}}
+}