[OpenMP] Add support for nested 'declare target' directives

Add the capability to nest multiple declare target directives 
- including header files within a declare target region.

Differential Revision: https://reviews.llvm.org/D51378

Patch by Patrick Lyster

llvm-svn: 341766

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -8783,8 +8783,6 @@ def warn_omp_linear_step_zero : Warning<
 def warn_omp_alignment_not_power_of_two : Warning<
   "aligned clause will be ignored because the requested alignment is not a power of 2">,
   InGroup<OpenMPClauses>;
-def err_omp_enclosed_declare_target : Error<
-  "declare target region may not be enclosed within another declare target region">;
 def err_omp_invalid_target_decl : Error<
   "%0 used in declare target directive is not a variable or a function name">;
 def err_omp_declare_target_multiple : Error<

clang/include/clang/Sema/Sema.h

@@ -8601,8 +8601,8 @@ public:
   //
 private:
   void *VarDataSharingAttributesStack;
-  /// Set to true inside '#pragma omp declare target' region.
-  bool IsInOpenMPDeclareTargetContext = false;
+  /// Number of nested '#pragma omp declare target' directives.
+  unsigned DeclareTargetNestingLevel = 0;
   /// Initialization of data-sharing attributes stack.
   void InitDataSharingAttributesStack();
   void DestroyDataSharingAttributesStack();
@@ -8736,7 +8736,7 @@ public:
                                    SourceLocation IdLoc = SourceLocation());
   /// Return true inside OpenMP declare target region.
   bool isInOpenMPDeclareTargetContext() const {
-    return IsInOpenMPDeclareTargetContext;
+    return DeclareTargetNestingLevel > 0;
   }
   /// Return true inside OpenMP target region.
   bool isInOpenMPTargetExecutionDirective() const;

clang/lib/Parse/ParseOpenMP.cpp

@@ -775,8 +775,8 @@ Parser::DeclGroupPtrTy Parser::ParseOpenMPDeclarativeDirectiveWithExtDecl(
 
     llvm::SmallVector<Decl *, 4>  Decls;
     DKind = parseOpenMPDirectiveKind(*this);
-    while (DKind != OMPD_end_declare_target && DKind != OMPD_declare_target &&
-           Tok.isNot(tok::eof) && Tok.isNot(tok::r_brace)) {
+    while (DKind != OMPD_end_declare_target && Tok.isNot(tok::eof) &&
+           Tok.isNot(tok::r_brace)) {
       DeclGroupPtrTy Ptr;
       // Here we expect to see some function declaration.
       if (AS == AS_none) {

clang/lib/Sema/SemaOpenMP.cpp

@@ -12960,19 +12960,14 @@ bool Sema::ActOnStartOpenMPDeclareTargetDirective(SourceLocation Loc) {
     Diag(Loc, diag::err_omp_region_not_file_context);
     return false;
   }
-  if (IsInOpenMPDeclareTargetContext) {
-    Diag(Loc, diag::err_omp_enclosed_declare_target);
-    return false;
-  }
-
-  IsInOpenMPDeclareTargetContext = true;
+  ++DeclareTargetNestingLevel;
   return true;
 }
 
 void Sema::ActOnFinishOpenMPDeclareTargetDirective() {
-  assert(IsInOpenMPDeclareTargetContext &&
+  assert(DeclareTargetNestingLevel > 0 &&
          "Unexpected ActOnFinishOpenMPDeclareTargetDirective");
-  IsInOpenMPDeclareTargetContext = false;
+  --DeclareTargetNestingLevel;
 }
 
 void Sema::ActOnOpenMPDeclareTargetName(Scope *CurScope,

clang/test/OpenMP/Inputs/declare_target_include.h

@@ -0,0 +1,3 @@
+#pragma omp declare target
+  void zyx();
+#pragma omp end declare target

clang/test/OpenMP/declare_target_ast_print.cpp

@@ -1,10 +1,10 @@
-// RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
-// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
-// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
+// RUN: %clang_cc1 -verify -fopenmp -I %S/Inputs -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -I %S/Inputs -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -I %S/Inputs -verify %s -ast-print | FileCheck %s
 
-// RUN: %clang_cc1 -verify -fopenmp-simd -ast-print %s | FileCheck %s
-// RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -emit-pch -o %t %s
-// RUN: %clang_cc1 -fopenmp-simd -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
+// RUN: %clang_cc1 -verify -fopenmp-simd -I %S/Inputs -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -I %S/Inputs -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp-simd -std=c++11 -include-pch %t -fsyntax-only -I %S/Inputs -verify %s -ast-print | FileCheck %s
 // expected-no-diagnostics
 
 #ifndef HEADER
@@ -191,6 +191,32 @@ int baz() { return 1; }
 // CHECK: }
 // CHECK: #pragma omp end declare target
 
+#pragma omp declare target
+  #include "declare_target_include.h"
+  void xyz();
+#pragma omp end declare target
+
+// CHECK: #pragma omp declare target
+// CHECK: void zyx();
+// CHECK: #pragma omp end declare target
+// CHECK: #pragma omp declare target
+// CHECK: void xyz();
+// CHECK: #pragma omp end declare target
+
+#pragma omp declare target
+  #pragma omp declare target
+    void abc();
+  #pragma omp end declare target
+  void cba();
+#pragma omp end declare target
+
+// CHECK: #pragma omp declare target
+// CHECK: void abc();
+// CHECK: #pragma omp end declare target
+// CHECK: #pragma omp declare target
+// CHECK: void cba();
+// CHECK: #pragma omp end declare target
+
 int main (int argc, char **argv) {
   foo();
   foo_c();

clang/test/OpenMP/declare_target_messages.cpp

@@ -59,8 +59,19 @@ void t2() {
   }
 }
 
+#pragma omp declare target
+  void abc();
+#pragma omp end declare target
+void cba();
+#pragma omp end declare target // expected-error {{unexpected OpenMP directive '#pragma omp end declare target'}}
 
-#pragma omp declare target // expected-note {{to match this '#pragma omp declare target'}}
+#pragma omp declare target  
+  #pragma omp declare target
+    void def();
+  #pragma omp end declare target
+  void fed();
+
+#pragma omp declare target
 #pragma omp threadprivate(a) // expected-note {{defined as threadprivate or thread local}}
 extern int b;
 int g;
@@ -100,9 +111,12 @@ void foo(int p) {
   f();
   c();
 }
-#pragma omp declare target // expected-error {{expected '#pragma omp end declare target'}}
+#pragma omp declare target
 void foo1() {}
 #pragma omp end declare target
+
+#pragma omp end declare target
+#pragma omp end declare target
 #pragma omp end declare target // expected-error {{unexpected OpenMP directive '#pragma omp end declare target'}}
 
 int C::method() {