[DWARF5] Added support for DW_AT_noreturn attribute to be emitted for C++ class member functions.

[SouraVX]

Summary

This Patch adds support in clang C++ frontend to emit DW_AT_noreturn for C++ class member functions.

[aprantl]

LGTM with updated testcase, thanks!

llvm/test/DebugInfo/X86/noreturn_cpp11.ll

59–63

Please remove all stringified attributes that aren't strictly necessary for the test.

[SouraVX]

Thanks Adrian for review!
Addressing your review comments.

[SouraVX]

llvm/test/DebugInfo/X86/noreturn_cpp11.ll

59–63

Done!

[SouraVX]

In D68697#1709680, @SouraVX wrote:

Thanks Adrian for review!
Addressing your review comments.

Could you please commit these changes for me, Thanks!

[aprantl]

Ah sorry. While preparing this for commit I realized that the CGDebugInfo change is untested. Can you add a Clang test that checks that CFE is emitting the expected LLVM IR?

[SouraVX]

Added test case in CFE for checking expected LLVM IR emission.

clang/lib/CodeGen/CGDebugInfo.cpp

       // it knows the dynamic type of an object.
       ThisAdjustment = CGM.getCXXABI()
                            .getVirtualFunctionPrologueThisAdjustment(GD)
                            .getQuantity();
     }
     ContainingType = RecordTy;
   }
 
+  if (Method->isNoReturn())
+    Flags |= llvm::DINode::FlagNoReturn;
   if (Method->isStatic())
     Flags |= llvm::DINode::FlagStaticMember;
   if (Method->isImplicit())
     Flags |= llvm::DINode::FlagArtificial;
   Flags |= getAccessFlag(Method->getAccess(), Method->getParent());
   if (const auto *CXXC = dyn_cast<CXXConstructorDecl>(Method)) {
     if (CXXC->isExplicit())
       Flags |= llvm::DINode::FlagExplicit;

llvm/test/DebugInfo/X86/noreturn_cpp11.ll

 ; RUN: %llc_dwarf -filetype=obj < %s | llvm-dwarfdump -debug-info - | FileCheck %s
 ; REQUIRES: object-emission
 
 ; Generated by clang++ -S -c -std=c++11 --emit-llvm -g from the following C++11 source:
-; [[ noreturn ]] void f() {
-;   throw 1;
-; }
+;class foo {
+;[[noreturn]] void foo_member(){throw 1;}
+;};
+;
+;[[ noreturn ]] void f() {
+;    throw 1;
+;}
+;
+;void func(){
+;    foo object;
+;}
 
 ; CHECK: DW_TAG_subprogram
 ; CHECK-NOT: DW_TAG
 ; CHECK: DW_AT_name{{.*}}"f"
 ; CHECK-NOT: DW_TAG
 ; CHECK: DW_AT_noreturn
-
+; CHECK: DW_TAG_class_type
+; CHECK: DW_TAG_subprogram
+; CHECK: DW_AT_name{{.*}}"foo_member"
+; CHECK: DW_AT_noreturn
 ; ModuleID = 'test.cpp'
-source_filename = "test.cpp"
-target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+source_filename = "noreturn1.cpp"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
-@_ZTIi = external constant i8*
+%class.foo = type { i8 }
 
-; Function Attrs: noreturn
-define void @_Z1fv() #0 !dbg !6 {
-entry:
-  %exception = call i8* @__cxa_allocate_exception(i64 4) #1, !dbg !9
-  %0 = bitcast i8* %exception to i32*, !dbg !9
-  store i32 1, i32* %0, align 16, !dbg !9
-  call void @__cxa_throw(i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null) #2, !dbg !10
-  unreachable, !dbg !9
+@_ZTIi = external dso_local constant i8*
 
-return:                                           ; No predecessors!
-  ret void, !dbg !12
+; Function Attrs: noinline noreturn optnone uwtable
+define dso_local void @_Z1fv() #0 !dbg !7 {
+  %1 = call i8* @__cxa_allocate_exception(i64 4) #3, !dbg !10
+  %2 = bitcast i8* %1 to i32*, !dbg !10
+  store i32 1, i32* %2, align 16, !dbg !10
+  call void @__cxa_throw(i8* %1, i8* bitcast (i8** @_ZTIi to i8*), i8* null) #4, !dbg !10
+  unreachable, !dbg !10
 }
 
-declare i8* @__cxa_allocate_exception(i64)
+declare dso_local i8* @__cxa_allocate_exception(i64)
+
+declare dso_local void @__cxa_throw(i8*, i8*, i8*)
+
+; Function Attrs: noinline nounwind optnone uwtable
+define dso_local void @_Z4funcv() #1 !dbg !11 {
+  %1 = alloca %class.foo, align 1
+  call void @llvm.dbg.declare(metadata %class.foo* %1, metadata !12, metadata !DIExpression()), !dbg !19
+  ret void, !dbg !20
+}
 
-declare void @__cxa_throw(i8*, i8*, i8*)
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
 
-attributes #0 = { noreturn }
+attributes #0 = { noinline noreturn optnone uwtable }
+attributes #1 = { noinline nounwind optnone uwtable }
+attributes #2 = { nounwind readnone speculatable willreturn }
+attributes #3 = { nounwind }
+attributes #4 = { noreturn }
 
 !llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!3, !4}
-!llvm.ident = !{!5}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 4.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
-!1 = !DIFile(filename: "test.cpp", directory: "/home/del/test")
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_11, file: !1, producer: "clang version 10.0.0 (https://github.com/llvm/llvm-project.git 3fcdd25ad5566114ac3322dcbf71d3c38bfec1ed)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/home/sourabh/work/dwarf/c_c++/c++11")
 !2 = !{}
 !3 = !{i32 2, !"Dwarf Version", i32 4}
 !4 = !{i32 2, !"Debug Info Version", i32 3}
-!5 = !{!"clang version 4.0.0"}
-!6 = distinct !DISubprogram(name: "f", linkageName: "_Z1fv", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped | DIFlagNoReturn, isOptimized: false, unit: !0, retainedNodes: !2)
-!7 = !DISubroutineType(types: !8)
-!8 = !{null}
-!9 = !DILocation(line: 2, column: 5, scope: !6)
-!10 = !DILocation(line: 2, column: 5, scope: !11)
-!11 = !DILexicalBlockFile(scope: !6, file: !1, discriminator: 1)
-!12 = !DILocation(line: 3, column: 1, scope: !6)
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0 (https://github.com/llvm/llvm-project.git 3fcdd25ad5566114ac3322dcbf71d3c38bfec1ed)"}
+!7 = distinct !DISubprogram(name: "f", linkageName: "_Z1fv", scope: !1, file: !1, line: 5, type: !8, scopeLine: 5, flags: DIFlagPrototyped | DIFlagNoReturn, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null}
+!10 = !DILocation(line: 6, column: 5, scope: !7)
+!11 = distinct !DISubprogram(name: "func", linkageName: "_Z4funcv", scope: !1, file: !1, line: 9, type: !8, scopeLine: 9, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!12 = !DILocalVariable(name: "object", scope: !11, file: !1, line: 10, type: !13)
+!13 = distinct !DICompositeType(tag: DW_TAG_class_type, name: "foo", file: !1, line: 1, size: 8, flags: DIFlagTypePassByValue, elements: !14, identifier: "_ZTS3foo")
+!14 = !{!15}
+!15 = !DISubprogram(name: "foo_member", linkageName: "_ZN3foo10foo_memberEv", scope: !13, file: !1, line: 2, type: !16, scopeLine: 2, flags: DIFlagPrototyped | DIFlagNoReturn, spFlags: 0)
+!16 = !DISubroutineType(types: !17)
+!17 = !{null, !18}
+!18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!19 = !DILocation(line: 10, column: 9, scope: !11)
+!20 = !DILocation(line: 11, column: 1, scope: !11)