DebugInfo: Support namespace aliases as DW_TAG_imported_declaration i…

…nstead of DW_TAG_imported_module

I really should read the spec more often (and test GCC more often too).
I just assumed that namespace aliases would be the same as using
directives, except with a name. But apparently that's not how the DWARF
standards suggests they be implemented. DWARF4 provides an example and
other non-normative text suggesting that namespace aliases be
implemented by named imported declarations intsead of named imported
modules.

So be it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205685 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/DIBuilder.h

@@ -647,24 +647,27 @@ namespace llvm {
     /// @param NS The namespace being imported here
     /// @param Line Line number
     DIImportedEntity createImportedModule(DIScope Context, DINameSpace NS,
-                                          unsigned Line,
-                                          StringRef Name = StringRef());
+                                          unsigned Line);
 
     /// \brief Create a descriptor for an imported module.
     /// @param Context The scope this module is imported into
     /// @param NS An aliased namespace
     /// @param Line Line number
     DIImportedEntity createImportedModule(DIScope Context, DIImportedEntity NS,
-                                          unsigned Line, StringRef Name);
+                                          unsigned Line);
 
     /// \brief Create a descriptor for an imported function.
     /// @param Context The scope this module is imported into
     /// @param Decl The declaration (or definition) of a function, type, or
     ///             variable
     /// @param Line Line number
+    DIImportedEntity createImportedDeclaration(DIScope Context, DIScope Decl,
+                                               unsigned Line,
+                                               StringRef Name = StringRef());
     DIImportedEntity createImportedDeclaration(DIScope Context,
-                                               DIScope Decl,
-                                               unsigned Line);
+                                               DIImportedEntity NS,
+                                               unsigned Line,
+                                               StringRef Name = StringRef());
 
     /// insertDeclare - Insert a new llvm.dbg.declare intrinsic call.
     /// @param Storage     llvm::Value of the variable

lib/IR/DIBuilder.cpp

@@ -146,21 +146,21 @@ DICompileUnit DIBuilder::createCompileUnit(unsigned Lang, StringRef Filename,
 }
 
 static DIImportedEntity
-createImportedModule(LLVMContext &C, DIScope Context, DIDescriptor NS,
-                     unsigned Line, StringRef Name,
-                     SmallVectorImpl<TrackingVH<MDNode> > &AllImportedModules) {
+createImportedModule(LLVMContext &C, dwarf::Tag Tag, DIScope Context,
+                     Value *NS, unsigned Line, StringRef Name,
+                     SmallVectorImpl<TrackingVH<MDNode>> &AllImportedModules) {
   const MDNode *R;
   if (Name.empty()) {
     Value *Elts[] = {
-      GetTagConstant(C, dwarf::DW_TAG_imported_module),
+      GetTagConstant(C, Tag),
       Context,
       NS,
       ConstantInt::get(Type::getInt32Ty(C), Line),
     };
     R = MDNode::get(C, Elts);
   } else {
     Value *Elts[] = {
-      GetTagConstant(C, dwarf::DW_TAG_imported_module),
+      GetTagConstant(C, Tag),
       Context,
       NS,
       ConstantInt::get(Type::getInt32Ty(C), Line),
@@ -175,33 +175,32 @@ createImportedModule(LLVMContext &C, DIScope Context, DIDescriptor NS,
 }
 
 DIImportedEntity DIBuilder::createImportedModule(DIScope Context,
-                                                 DINameSpace NS, unsigned Line,
-                                                 StringRef Name) {
-  return ::createImportedModule(VMContext, Context, NS, Line, Name,
-                                AllImportedModules);
+                                                 DINameSpace NS,
+                                                 unsigned Line) {
+  return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
+                                Context, NS, Line, StringRef(), AllImportedModules);
 }
 
 DIImportedEntity DIBuilder::createImportedModule(DIScope Context,
                                                  DIImportedEntity NS,
-                                                 unsigned Line,
-                                                 StringRef Name) {
-  return ::createImportedModule(VMContext, Context, NS, Line, Name,
-                                AllImportedModules);
+                                                 unsigned Line) {
+  return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
+                                Context, NS, Line, StringRef(), AllImportedModules);
 }
 
 DIImportedEntity DIBuilder::createImportedDeclaration(DIScope Context,
                                                       DIScope Decl,
-                                                      unsigned Line) {
-  Value *Elts[] = {
-    GetTagConstant(VMContext, dwarf::DW_TAG_imported_declaration),
-    Context,
-    Decl.getRef(),
-    ConstantInt::get(Type::getInt32Ty(VMContext), Line),
-  };
-  DIImportedEntity M(MDNode::get(VMContext, Elts));
-  assert(M.Verify() && "Imported module should be valid");
-  AllImportedModules.push_back(TrackingVH<MDNode>(M));
-  return M;
+                                                      unsigned Line, StringRef Name) {
+  return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_declaration,
+                                Context, Decl.getRef(), Line, Name,
+                                AllImportedModules);
+}
+
+DIImportedEntity DIBuilder::createImportedDeclaration(DIScope Context,
+                                                      DIImportedEntity Imp,
+                                                      unsigned Line, StringRef Name) {
+  return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_declaration,
+                                Context, Imp, Line, Name, AllImportedModules);
 }
 
 /// createFile - Create a file descriptor to hold debugging information

test/DebugInfo/namespace.ll

@@ -73,13 +73,13 @@
 ; CHECK-NEXT: DW_AT_decl_line{{.*}}(0x16)
 ; CHECK-NEXT: DW_AT_import{{.*}}=> {[[I]]})
 ; CHECK-NOT: NULL
-; CHECK: [[X:0x[0-9a-f]*]]:{{ *}}DW_TAG_imported_module
+; CHECK: [[X:0x[0-9a-f]*]]:{{ *}}DW_TAG_imported_declaration
 ; CHECK-NEXT: DW_AT_decl_file{{.*}}(0x0[[F2]])
 ; CHECK-NEXT: DW_AT_decl_line{{.*}}(0x18)
 ; CHECK-NEXT: DW_AT_import{{.*}}=> {[[NS1]]})
 ; CHECK-NEXT: DW_AT_name{{.*}}"X"
 ; CHECK-NOT: NULL
-; CHECK: DW_TAG_imported_module
+; CHECK: DW_TAG_imported_declaration
 ; CHECK-NEXT: DW_AT_decl_file{{.*}}(0x0[[F2]])
 ; CHECK-NEXT: DW_AT_decl_line{{.*}}(0x19)
 ; CHECK-NEXT: DW_AT_import{{.*}}=> {[[X]]})
@@ -236,8 +236,8 @@ attributes #1 = { nounwind readnone }
 !36 = metadata !{i32 786468}
 !37 = metadata !{i32 786440, metadata !14, metadata !10, i32 21} ; [ DW_TAG_imported_declaration ]
 !38 = metadata !{i32 786440, metadata !14, metadata !20, i32 22} ; [ DW_TAG_imported_declaration ]
-!39 = metadata !{i32 786490, metadata !14, metadata !7, i32 24, metadata !"X"} ; [ DW_TAG_imported_module ]
-!40 = metadata !{i32 786490, metadata !14, metadata !39, i32 25, metadata !"Y"} ; [ DW_TAG_imported_module ]
+!39 = metadata !{i32 786440, metadata !14, metadata !7, i32 24, metadata !"X"} ; [ DW_TAG_imported_declaration ]
+!40 = metadata !{i32 786440, metadata !14, metadata !39, i32 25, metadata !"Y"} ; [ DW_TAG_imported_declaration ]
 !41 = metadata !{i32 3, i32 0, metadata !4, null}
 !42 = metadata !{i32 786689, metadata !10, metadata !"", metadata !15, i32 16777220, metadata !13, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [line 4]
 !43 = metadata !{i32 4, i32 0, metadata !10, null}