Debug Info (-gmodules): emit full types for non-anchored template specializations

Before this patch, clang would emit a (module-)forward declaration for
template instantiations that are not anchored by an explicit template
instantiation, but still are guaranteed to be available in an imported
module. Unfortunately detecting the owning module doesn't reliably
work when local submodule visibility is enabled and the template is
inside a cross-module namespace.

This make clang debuggable again with -gmodules and LSV enabled.

rdar://problem/41552377

llvm-svn: 345109

7 files changed, 131 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index bcd5338ac05..0d42befa5ab 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1955,8 +1955,17 @@ static bool isDefinedInClangModule(const RecordDecl *RD) {
   if (auto *CXXDecl = dyn_cast<CXXRecordDecl>(RD)) {
     if (!CXXDecl->isCompleteDefinition())
       return false;
+    // Check wether RD is a template.
     auto TemplateKind = CXXDecl->getTemplateSpecializationKind();
     if (TemplateKind != TSK_Undeclared) {
+      // Unfortunately getOwningModule() isn't accurate enough to find the
+      // owning module of a ClassTemplateSpecializationDecl that is inside a
+      // namespace spanning multiple modules.
+      bool Explicit = false;
+      if (auto *TD = dyn_cast<ClassTemplateSpecializationDecl>(CXXDecl))
+        Explicit = TD->isExplicitInstantiationOrSpecialization();
+      if (!Explicit && CXXDecl->getEnclosingNamespaceContext())
+        return false;
       // This is a template, check the origin of the first member.
       if (CXXDecl->field_begin() == CXXDecl->field_end())
         return TemplateKind == TSK_ExplicitInstantiationDeclaration;
diff --git a/clang/test/Modules/ExtDebugInfo.cpp b/clang/test/Modules/ExtDebugInfo.cpp
index c57f1f034eb..592612b9a5d 100644
--- a/clang/test/Modules/ExtDebugInfo.cpp
+++ b/clang/test/Modules/ExtDebugInfo.cpp
@@ -83,11 +83,11 @@ void foo() {
 // CHECK: ![[NS]] = !DINamespace(name: "DebugCXX", scope: ![[MOD:[0-9]+]])
 // CHECK: ![[MOD]] = !DIModule(scope: null, name: {{.*}}DebugCXX
 
-// This type is anchored in the module by an explicit template instantiation.
+// This type is not anchored in the module by an explicit template instantiation.
 // CHECK: !DICompositeType(tag: DW_TAG_class_type,
 // CHECK-SAME:             name: "Template<long, DebugCXX::traits<long> >",
 // CHECK-SAME:             scope: ![[NS]],
-// CHECK-SAME:             flags: DIFlagFwdDecl,
+// CHECK-SAME:             elements:
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX8TemplateIlNS_6traitsIlEEEE")
 
 // This type is anchored in the module by an explicit template instantiation.
diff --git a/clang/test/Modules/Inputs/lsv-debuginfo/A/ADT.h b/clang/test/Modules/Inputs/lsv-debuginfo/A/ADT.h
new file mode 100644
index 00000000000..f48d4f7820a
--- /dev/null
+++ b/clang/test/Modules/Inputs/lsv-debuginfo/A/ADT.h
@@ -0,0 +1,45 @@
+#ifndef ADT
+#define ADT
+
+#ifdef WITH_NAMESPACE
+namespace llvm {
+#endif
+template <unsigned Alignment, unsigned Size>
+struct AlignedCharArray {
+  alignas(Alignment) char buffer[Size];
+};
+
+template <typename T1>
+class AlignerImpl {
+  T1 t1;
+};
+
+template <typename T1>
+union SizerImpl {
+  char arr1[sizeof(T1)];
+};
+
+template <typename T1>
+struct AlignedCharArrayUnion
+    : AlignedCharArray<alignof(AlignerImpl<T1>), sizeof(SizerImpl<T1>)> {};
+
+template <typename T, unsigned N>
+struct SmallVectorStorage {
+  AlignedCharArrayUnion<T> InlineElts[N];
+};
+template <typename T, unsigned N>
+class SmallVector : SmallVectorStorage<T, N> {};
+
+template <typename T>
+struct OptionalStorage {
+  AlignedCharArrayUnion<T> storage;
+};
+template <typename T>
+class Optional {
+  OptionalStorage<T> Storage;
+};
+
+#ifdef WITH_NAMESPACE
+} // namespace llvm
+#endif
+#endif
diff --git a/clang/test/Modules/Inputs/lsv-debuginfo/B/B.h b/clang/test/Modules/Inputs/lsv-debuginfo/B/B.h
new file mode 100644
index 00000000000..c00bc3cddbf
--- /dev/null
+++ b/clang/test/Modules/Inputs/lsv-debuginfo/B/B.h
@@ -0,0 +1,14 @@
+#ifndef B_H
+#define B_H
+#include <A/ADT.h>
+#include <C/C.h>
+
+namespace llvm {
+struct S {
+  unsigned a, b, c, d;
+};
+class C {
+  Optional<S> S;
+};
+}
+#endif
diff --git a/clang/test/Modules/Inputs/lsv-debuginfo/C/C.h b/clang/test/Modules/Inputs/lsv-debuginfo/C/C.h
new file mode 100644
index 00000000000..52c6e4dbac9
--- /dev/null
+++ b/clang/test/Modules/Inputs/lsv-debuginfo/C/C.h
@@ -0,0 +1,13 @@
+#ifndef C_H
+#define C_H
+#include <A/ADT.h>
+
+namespace llvm {
+class D {
+  struct Q {
+    unsigned a, b, c, d;
+  };
+  SmallVector<Q, 4> q;
+};
+} // namespace llvm
+#endif
diff --git a/clang/test/Modules/Inputs/lsv-debuginfo/module.modulemap b/clang/test/Modules/Inputs/lsv-debuginfo/module.modulemap
new file mode 100644
index 00000000000..5bb044908dc
--- /dev/null
+++ b/clang/test/Modules/Inputs/lsv-debuginfo/module.modulemap
@@ -0,0 +1,9 @@
+module A {
+  umbrella "A" module * { export * }
+}
+module B {
+  umbrella "B" module * { export * }
+}
+module C {
+  umbrella "C" module * { export * }
+}
diff --git a/clang/test/Modules/lsv-debuginfo.cpp b/clang/test/Modules/lsv-debuginfo.cpp
new file mode 100755
index 00000000000..4a2644f6b31
--- /dev/null
+++ b/clang/test/Modules/lsv-debuginfo.cpp
@@ -0,0 +1,39 @@
+// Test C++ -gmodules debug info in the PCMs with local submodule visibility.
+// REQUIRES: asserts
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -triple %itanium_abi_triple    \
+// RUN:   -fmodules-local-submodule-visibility %s \
+// RUN:   -dwarf-ext-refs -fmodule-format=obj -debug-info-kind=standalone \
+// RUN:   -dwarf-version=4 -fmodules -fimplicit-module-maps \
+// RUN:   -fmodules-cache-path="%t" -o %t.ll -I%S/Inputs/lsv-debuginfo \
+// RUN:   -mllvm -debug-only=pchcontainer &>%t-mod.ll
+// RUN: cat %t-mod.ll | FileCheck %s
+
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -triple %itanium_abi_triple    \
+// RUN:   -fmodules-local-submodule-visibility %s \
+// RUN:   -dwarf-ext-refs -fmodule-format=obj -debug-info-kind=standalone \
+// RUN:   -dwarf-version=4 -fmodules -fimplicit-module-maps \
+// RUN:   -fmodules-cache-path="%t" -o %t.ll -I%S/Inputs/lsv-debuginfo \
+// RUN:   -mllvm -debug-only=pchcontainer &>%t-mod.ll \
+// RUN:   -DWITH_NAMESPACE
+// RUN: cat %t-mod.ll | FileCheck %s
+
+// ADT
+// CHECK: @__clang_ast =
+
+// B
+// CHECK: @__clang_ast =
+
+// This type isn't anchored anywhere, expect a full definition.
+// CHECK: !DICompositeType({{.*}}, name: "AlignedCharArray<4, 16>",
+// CHECK-SAME:             elements:
+
+// C
+// CHECK: @__clang_ast =
+
+// Here, too.
+// CHECK: !DICompositeType({{.*}}, name: "AlignedCharArray<4, 16>",
+// CHECK-SAME:             elements:
+
+#include <B/B.h>