r321845 - Debug Info: Support DW_AT_calling_convention on composite types.

[David Blaikie via cfe-commits]

Excellent :)

On Mon, Jan 8, 2018 at 8:39 AM Adrian Prantl <aprantl at apple.com> wrote:

>
> On Jan 8, 2018, at 8:14 AM, David Blaikie <dblaikie at gmail.com> wrote:
>
> 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))
>
>
> Yes, this was in fact my primary motivation for the feature. Since the
> code is asking the ABI object, it looks like this might work out of the box
> with the trivial_abi attribute, but I will definitely at least add a
> testcase once it's in.
>
> -- adrian
>
>
> 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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