[llvm-dev] Instrument intrinsic invalid

Chen, Yuanfang via llvm-dev llvm-dev at lists.llvm.org
Mon Jul 20 10:07:10 PDT 2020

Could you please elaborate on what are you trying to do? `llvm.dbg.label` is for debuginfo generation of the program being compiled, not for attaching user info and passing around.

From: Jinyan <phantom0308 at zju.edu.cn>
Sent: Sunday, July 19, 2020 2:16 AM
To: Chen, Yuanfang
Subject: Re: Re: [llvm-dev] Instrument intrinsic invalid

Wow ! It seems insertLabel internal is also use builder to create, the key point in my bug is to convert the MDNode* to a DILabel*, after passing a DILAble as arg, it works, thks! I want to use llvm.dbg.label to instrument some machine instructions at the backend, but now the metadata must obey the format of DILabel, I can only pass my info in name field... Are there any existing intrinsic that can be used to pass arbitrary metadata ? Please you get me some suggestion ?

> -----Original Messages-----
> From: "Chen, Yuanfang" <Yuanfang.Chen at sony.com>
> Sent Time: 2020-07-19 15:19:39 (Sunday)
> To: "llvm-dev at lists.llvm.org" <llvm-dev at lists.llvm.org>, Jinyan <phantom0308 at zju.edu.cn>
> Cc:
> Subject: Re: [llvm-dev] Instrument intrinsic invalid
> Hi,
> A successfully printed module could still be invalid such as this case. The problem is that the metadata should contain a DILabel instead of a string. Try using DIBuilder::insertLabel instead.
> ________________________________________
> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of Jinyan via llvm-dev <llvm-dev at lists.llvm.org>
> Sent: Saturday, July 18, 2020 11:48 PM
> To: llvm-dev at lists.llvm.org
> Subject: [llvm-dev] Instrument intrinsic invalid
> Hi, I try to use llvm-dis to disassemble the result after opt, my pass will add a intrinsic after the load instruction, like following:
> bool fpscan::ldAddMetadata (Instruction *Inst, StringRef c) {
>     std::vector<Metadata *> dataTuples;
>     // Add metadata in list
>     dataTuples.push_back(MDString::get(Inst->getContext(), c));
>     MDNode* N = MDNode::get(Inst->getContext(), dataTuples);
>     Value* meta = MetadataAsValue::get(Inst->getContext(), N);
>     std::vector<Value*> args;
>     args.push_back(meta);
>     IRBuilder<> Builder(Inst->getNextNode());
>     Builder.CreateCall(dbglabelPtr, args, "");
> }
> And before my pass finish, I print the IR, it shows I successfully add the intrinsic
>   %5 = load i32 (i32, i32)*, i32 (i32, i32)** %1, align 8, !dbg !35, !ppp.load !36
>   call void @llvm.dbg.label(metadata !36), !dbg !37
> ...
> ; Function Attrs: nounwind readnone speculatable willreturn
> declare void @llvm.dbg.label(metadata) #1
> But, when I use llvm-dis to disassemble the .bc generated by opt, it ignore the code I insert:
> invalid llvm.dbg.label intrinsic variable
>   call void @llvm.dbg.label(metadata !36), !dbg !37
> !36 = !{!"dbg1", !"dbgfromLoad"}
> llvm-dis: warning: ignoring invalid debug info in test.bc
> How to fix this warning ? thks
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