r321845 - Debug Info: Support DW_AT_calling_convention on composite types.

[Adrian Prantl via cfe-commits]

Author: adrian
Date: Thu Jan  4 17:13:52 2018
New Revision: 321845

URL: http://llvm.org/viewvc/llvm-project?rev=321845&view=rev
Log:
Debug Info: Support DW_AT_calling_convention on composite types.
This implements the DWARF 5 feature described at
http://www.dwarfstd.org/ShowIssue.php?issue=141215.1

This allows a consumer to understand whether a composite data type is
trivially copyable and thus should be passed by value instead of by
reference. The canonical example is being able to distinguish the
following two types:

  // S is not trivially copyable because of the explicit destructor.
  struct S {
     ~S() {}
  };

  // T is a POD type.
  struct T {
    ~T() = default;
  };

<rdar://problem/36034993>
Differential Revision: https://reviews.llvm.org/D41039

Added:
    cfe/trunk/test/CodeGenCXX/debug-info-composite-cc.cpp
Modified:
    cfe/trunk/lib/CodeGen/CGDebugInfo.cpp

Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=321845&r1=321844&r2=321845&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Thu Jan  4 17:13:52 2018
@@ -2803,9 +2803,18 @@ llvm::DICompositeType *CGDebugInfo::Crea
 
   SmallString<256> FullName = getUniqueTagTypeName(Ty, CGM, TheCU);
 
+  // Explicitly record the calling convention for C++ records.
+  auto Flags = llvm::DINode::FlagZero;
+  if (auto CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
+    if (CGM.getCXXABI().getRecordArgABI(CXXRD) == CGCXXABI::RAA_Indirect)
+      Flags |= llvm::DINode::FlagTypePassByReference;
+    else
+      Flags |= llvm::DINode::FlagTypePassByValue;
+  }
+
   llvm::DICompositeType *RealDecl = DBuilder.createReplaceableCompositeType(
       getTagForRecord(RD), RDName, RDContext, DefUnit, Line, 0, Size, Align,
-      llvm::DINode::FlagZero, FullName);
+      Flags, FullName);
 
   // Elements of composite types usually have back to the type, creating
   // uniquing cycles.  Distinct nodes are more efficient.

Added: cfe/trunk/test/CodeGenCXX/debug-info-composite-cc.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/debug-info-composite-cc.cpp?rev=321845&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/debug-info-composite-cc.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/debug-info-composite-cc.cpp Thu Jan  4 17:13:52 2018
@@ -0,0 +1,48 @@
+// RUN: %clang_cc1 -emit-llvm -debug-info-kind=standalone -triple %itanium_abi_triple %s -o - | FileCheck %s
+
+// Not trivially copyable because of the explicit destructor.
+// CHECK-DAG: !DICompositeType({{.*}}, name: "RefDtor",{{.*}}flags: DIFlagTypePassByReference
+struct RefDtor {
+  int i;
+  ~RefDtor() {}
+} refDtor;
+
+// Not trivially copyable because of the explicit copy constructor.
+// CHECK-DAG: !DICompositeType({{.*}}, name: "RefCopy",{{.*}}flags: DIFlagTypePassByReference
+struct RefCopy {
+  int i;
+  RefCopy() = default;
+  RefCopy(RefCopy &Copy) {}
+} refCopy;
+
+// Not trivially copyable because of the explicit move constructor.
+// CHECK-DAG: !DICompositeType({{.*}}, name: "RefMove",{{.*}}flags: DIFlagTypePassByReference
+struct RefMove {
+  int i;
+  RefMove() = default;
+  RefMove(RefMove &&Move) {}
+} refMove;
+
+// POD-like type even though it defines a destructor.
+// CHECK-DAG: !DICompositeType({{.*}}, name: "Podlike", {{.*}}flags: DIFlagTypePassByValue
+struct Podlike {
+  int i;
+  Podlike() = default;
+  Podlike(Podlike &&Move) = default;
+  ~Podlike() = default;
+} podlike;
+
+
+// This is a POD type.
+// CHECK-DAG: !DICompositeType({{.*}}, name: "Pod",{{.*}}flags: DIFlagTypePassByValue
+struct Pod {
+  int i;
+} pod;
+
+// This is definitely not a POD type.
+// CHECK-DAG: !DICompositeType({{.*}}, name: "Complex",{{.*}}flags: DIFlagTypePassByReference
+struct Complex {
+  Complex() {}
+  Complex(Complex &Copy) : i(Copy.i) {};
+  int i;
+} complex;