[PATCH] D97673: [RFC] [[Coroutine] [Debug] Salvage dbg.values

[Hongtao Yu via Phabricator via llvm-commits]

hoy added a comment.

In D97673#3168739 <https://reviews.llvm.org/D97673#3168739>, @ChuanqiXu wrote:

> In D97673#3168737 <https://reviews.llvm.org/D97673#3168737>, @hoy wrote:
>
>> In D97673#3168709 <https://reviews.llvm.org/D97673#3168709>, @ChuanqiXu wrote:
>>
>>> @hoy The rationale here is that the dbg.declare intrinsics might be lost due to coroutine split. So we move the dbg.declare intrinsics to the place where the Storage is just created. So if it caused crash, I think we could skip the kind of case. Or it would be better to insert dbg.declare to the start of successor blocks in the case of invoke. (Would any other terminator return a value?) 
>>> BTW, there is nothing in your repro link.
>>
>> An invoke instruction is a call instruction that can throw exceptions. It is a block terminator and can return a value.  Looks like dbg.declare can only appear once so maybe we could only move it to one of the successors, or just skip this case.
>>
>> There is a test file in my repro link. The file is probably too large (40MB) to be rendered. Sorry for not being able to get a smaller repro case.
>
> Got it. I would try to fix this. Thanks for reporting this.

Thanks. I'm pasting the problematic code snippet in case my link doesn't work for you, but please let me know so that I'll find another way to share with you.

  %660 = invoke noalias nonnull i8* @_Znwm(i64 120) #20
            to label %.noexc unwind label %702, !dbg !304801
  
  .noexc:                                           ; preds = %653
    call void @llvm.dbg.value(metadata %"class.std::allocator.6883"* undef, metadata !304802, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 64)), !dbg !304803
    call void @llvm.dbg.value(metadata i8* %660, metadata !304802, metadata !DIExpression(DW_OP_LLVM_fragment, 64, 64)), !dbg !304803
    call void @llvm.dbg.value(metadata i8* %660, metadata !304804, metadata !DIExpression()), !dbg !304803
    call void @llvm.dbg.value(metadata i8* %660, metadata !303143, metadata !DIExpression()), !dbg !304805
    %661 = bitcast i8* %660 to %"class.std::_Sp_counted_base"*, !dbg !304808
    call void @_ZNSt16_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EEC2Ev(%"class.std::_Sp_counted_base"* nonnull dereferenceable(16) %661) #15, !dbg !304809
    %662 = bitcast i8* %660 to i32 (...)***, !dbg !304808
    store i32 (...)** bitcast (i8** getelementptr inbounds ({ [7 x i8*] }, { [7 x i8*] }* @_ZTVSt23_Sp_counted_ptr_inplaceIN7scribex17ScribeReadFlavourESaIS1_ELN9__gnu_cxx12_Lock_policyE2EE, i64 0, inrange i32 0, i64 2) to i32 (...)**), i32 (...)*** %662, align 8, !dbg !304808, !tbaa !302581
    call void @llvm.dbg.value(metadata i8* %660, metadata !303156, metadata !DIExpression()), !dbg !304810
    ....
    call void @llvm.dbg.declare(metadata i8* %660, metadata !303236, metadata !DIExpression(DW_OP_plus_uconst, 16, DW_OP_plus_uconst, 8)), !dbg !304825

The last dbg.declare will be moved to right after the first invoke instruction.


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