[DebugInfo] Emit ObjC methods as part of interface

As brought up during the discussion of the DWARF5 accelerator tables,
there is currently no way to associate Objective-C methods with the
interface they belong to, other than the .apple_objc accelerator table.

After due consideration we came to the conclusion that it makes more
sense to follow Pavel's suggestion of just emitting this information in
the .debug_info section. One concern was that categories were
emitted in the .apple_names as well, but it turns out that LLDB doesn't
rely on the accelerator tables for this information.

This patch changes the codegen behavior to emit subprograms for
structure types, like we do for C++. This will result in the
DW_TAG_subprogram being nested as a child under its
DW_TAG_structure_type. This behavior is only enabled for DWARF5 and
later, so we can have a unique code path in LLDB with regards to
obtaining the class methods.

This was tested on the LLDB side and doesn't lead to a regression.
There's already code in place to deal with member functions in C++,
which deals with this transparently.

For more background please refer to the discussion on the mailing list:
http://lists.llvm.org/pipermail/llvm-dev/2018-June/123986.html

Differential revision: https://reviews.llvm.org/D48241

llvm-svn: 335757

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index a0d5fd6..5a527cb 100644 (file)
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3346,6 +3346,27 @@ void CGDebugInfo::EmitFunctionStart(GlobalDecl GD, SourceLocation Loc,
   if (HasDecl && isa<FunctionDecl>(D))
     DeclCache[D->getCanonicalDecl()].reset(SP);
 
+  if (CGM.getCodeGenOpts().DwarfVersion >= 5) {
+    // Starting with DWARF V5 method declarations are emitted as children of
+    // the interface type.
+    if (const auto *OMD = dyn_cast_or_null<ObjCMethodDecl>(D)) {
+      const ObjCInterfaceDecl *ID = OMD->getClassInterface();
+      QualType QTy(ID->getTypeForDecl(), 0);
+      auto It = TypeCache.find(QTy.getAsOpaquePtr());
+      if (It != TypeCache.end()) {
+        llvm::DICompositeType *InterfaceDecl =
+            cast<llvm::DICompositeType>(It->second);
+        llvm::DISubprogram *FD = DBuilder.createFunction(
+            InterfaceDecl, Name, LinkageName, Unit, LineNo,
+            getOrCreateFunctionType(D, FnType, Unit), Fn->hasLocalLinkage(),
+            false /*definition*/, ScopeLine, Flags, CGM.getLangOpts().Optimize,
+            TParamsArray.get());
+        DBuilder.finalizeSubprogram(FD);
+        ObjCMethodCache[ID].push_back(FD);
+      }
+    }
+  }
+
   // Push the function onto the lexical block stack.
   LexicalBlockStack.emplace_back(SP);
 
@@ -4213,6 +4234,29 @@ void CGDebugInfo::finalize() {
     DBuilder.replaceTemporary(llvm::TempDIType(E.Decl), Ty);
   }
 
+  if (CGM.getCodeGenOpts().DwarfVersion >= 5) {
+    // Add methods to interface.
+    for (auto P : ObjCMethodCache) {
+      if (P.second.empty())
+        continue;
+
+      QualType QTy(P.first->getTypeForDecl(), 0);
+      auto It = TypeCache.find(QTy.getAsOpaquePtr());
+      assert(It != TypeCache.end());
+
+      llvm::DICompositeType *InterfaceDecl =
+          cast<llvm::DICompositeType>(It->second);
+
+      SmallVector<llvm::Metadata *, 16> EltTys;
+      auto CurrenetElts = InterfaceDecl->getElements();
+      EltTys.append(CurrenetElts.begin(), CurrenetElts.end());
+      for (auto &MD : P.second)
+        EltTys.push_back(MD);
+      llvm::DINodeArray Elements = DBuilder.getOrCreateArray(EltTys);
+      DBuilder.replaceArrays(InterfaceDecl, Elements);
+    }
+  }
+
   for (auto p : ReplaceMap) {
     assert(p.second);
     auto *Ty = cast<llvm::DIType>(p.second);

diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index a692bab..9f5e639 100644 (file)
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -98,6 +98,10 @@ class CGDebugInfo {
   /// Cache of previously constructed interfaces which may change.
   llvm::SmallVector<ObjCInterfaceCacheEntry, 32> ObjCInterfaceCache;
 
+  /// Cache of forward declarations for methods belonging to the interface.
+  llvm::DenseMap<const ObjCInterfaceDecl *, std::vector<llvm::DISubprogram *>>
+      ObjCMethodCache;
+
   /// Cache of references to clang modules and precompiled headers.
   llvm::DenseMap<const Module *, llvm::TrackingMDRef> ModuleCache;
 

diff --git a/clang/test/CodeGenObjC/debug-info-category.m b/clang/test/CodeGenObjC/debug-info-category.m
new file mode 100644 (file)
index 0000000..faca3a4
--- /dev/null
+++ b/clang/test/CodeGenObjC/debug-info-category.m
@@ -0,0 +1,52 @@
+// RUN: %clang_cc1 -dwarf-version=5 -emit-llvm -debug-info-kind=limited -w -triple x86_64-apple-darwin10 %s -o - | FileCheck %s --check-prefix CHECK --check-prefix DWARF5
+// RUN: %clang_cc1 -dwarf-version=4 -emit-llvm -debug-info-kind=limited -w -triple x86_64-apple-darwin10 %s -o - | FileCheck %s --check-prefix CHECK --check-prefix DWARF4
+
+@interface Foo {
+  int integer;
+}
+
+- (int)integer;
+- (id)integer:(int)_integer;
+@end
+
+@implementation Foo
+- (int)integer {
+  return integer;
+}
+
+- (id)integer:(int)_integer {
+  integer = _integer;
+  return self;
+}
+@end
+
+@interface Foo (Bar)
++ (id)zero:(Foo *)zeroend;
+- (id)add:(Foo *)addend;
+@end
+
+@implementation Foo (Bar)
++ (id)zero:(Foo *)zeroend {
+  return [self integer:0];
+}
+- (id)add:(Foo *)addend {
+  return [self integer:[self integer] + [addend integer]];
+}
+@end
+
+// CHECK: ![[STRUCT:.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Foo"
+
+// DWARF5: !DISubprogram(name: "-[Foo integer]", scope: ![[STRUCT]], {{.*}}isDefinition: false
+// DWARF5: !DISubprogram(name: "-[Foo integer:]", scope: ![[STRUCT]], {{.*}}isDefinition: false
+// DWARF5: !DISubprogram(name: "+[Foo(Bar) zero:]", scope: ![[STRUCT]], {{.*}}isDefinition: false
+// DWARF5: !DISubprogram(name: "-[Foo(Bar) add:]", scope: ![[STRUCT]], {{.*}}isDefinition: false
+
+// DWARF4-NOT: !DISubprogram(name: "-[Foo integer]", scope: ![[STRUCT]], {{.*}}isDefinition: false
+// DWARF4-NOT: !DISubprogram(name: "-[Foo integer:]", scope: ![[STRUCT]], {{.*}}isDefinition: false
+// DWARF4-NOT: !DISubprogram(name: "+[Foo(Bar) zero:]", scope: ![[STRUCT]], {{.*}}isDefinition: false
+// DWARF4-NOT: !DISubprogram(name: "-[Foo(Bar) add:]", scope: ![[STRUCT]], {{.*}}isDefinition: false
+
+// CHECK: = distinct !DISubprogram(name: "-[Foo integer]"{{.*}}isDefinition: true
+// CHECK: = distinct !DISubprogram(name: "-[Foo integer:]"{{.*}}isDefinition: true
+// CHECK: = distinct !DISubprogram(name: "+[Foo(Bar) zero:]"{{.*}}isDefinition: true
+// CHECK: = distinct !DISubprogram(name: "-[Foo(Bar) add:]"{{.*}}isDefinition: true