r321845 - Debug Info: Support DW_AT_calling_convention on composite types.

[David Blaikie via cfe-commits]

Great - are you tracking/planning to implement this for trivial_abi once
it's in? (was mentioned in the code review, but not sure if it's on your
plate/plan or not (no worries if it isn't, just keeping these things in
mind))

On Thu, Jan 4, 2018 at 5:14 PM Adrian Prantl via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> 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;
>
>
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