[llvm] r375012 - [DWARF5] Added support for DW_AT_noreturn attribute to be emitted for

Tue Oct 29 00:03:10 PDT 2019

Hi Adrian, David,

Maybe you guys are looking for this.
DW_AT_noreturn emission {LLVM functionality}is originally authored by --

https://reviews.llvm.org/D23167

My patch just augments it's emission for class member functions.

Thanks!
Sourabh

On Tue 29 Oct, 2019, 4:53 AM Adrian Prantl, <aprantl at apple.com> wrote:

> + Sourabh
>
> On Oct 28, 2019, at 4:20 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
> Looks like this is only the test, but not the functionality? What was the
> patch that committed the functionality? (I see a clang commit, but I guess
> there was probably an LLVM change somewhere to use the DIFlag to produce
> the actual DWARF attribute?)
>
> On Wed, Oct 16, 2019 at 9:28 AM Adrian Prantl via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: adrian
>> Date: Wed Oct 16 09:30:38 2019
>> New Revision: 375012
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=375012&view=rev
>> Log:
>> [DWARF5] Added support for DW_AT_noreturn attribute to be emitted for
>> C++ class member functions.
>>
>> Patch by Sourabh Singh Tomar!
>>
>> Differential Revision: https://reviews.llvm.org/D68697
>>
>> Modified:
>>     llvm/trunk/test/DebugInfo/X86/noreturn_cpp11.ll
>>
>> Modified: llvm/trunk/test/DebugInfo/X86/noreturn_cpp11.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/noreturn_cpp11.ll?rev=375012&r1=375011&r2=375012&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/DebugInfo/X86/noreturn_cpp11.ll (original)
>> +++ llvm/trunk/test/DebugInfo/X86/noreturn_cpp11.ll Wed Oct 16 09:30:38
>> 2019
>> @@ -2,56 +2,88 @@
>>  ; 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"
>>
>> - at _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
>> + at _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)
>>
>>
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>
>
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