[llvm-dev] CloneFunctionInto produces invalid debug info

[Sergei Larin via llvm-dev]

Yes, it does for us. My tree is couple days off the tip, and I see it there.

 

Sergei

 

From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Keno Fischer via llvm-dev
Sent: Thursday, June 15, 2017 1:25 PM
To: Adrian Prantl <aprantl at apple.com>
Cc: llvm-dev <llvm-dev at lists.llvm.org>
Subject: Re: [llvm-dev] CloneFunctionInto produces invalid debug info

 

This all looks very similar to a bug in the cloning stuff I fixed recently, so would be indeed good to know if this is still happening on master.

 

On Thu, Jun 15, 2017 at 2:23 PM, Adrian Prantl via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org> > wrote:

If you are doing this work based off LLVM trunk, could you send me your patch to reproduce the problem?

 

-- adrian

On Jun 15, 2017, at 8:31 AM, Matthias Bernad via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org> > wrote:

 

Hi!

 

We are currently working on a science project and implemented a FunctionPass that clones a function (more precisely a constructor of a struct/class) and adds a parameter.

 

First, we create a new function with a new function type, which includes the newly added parameter:

 

Function *NF = Function::Create(NewFTy, F.getLinkage(), F.getName() + "Cloned", F.getParent());

 

and after setting up the ValueToValueMapTy, we use the CloneFunctionInto method to clone the function body

 

CloneFunctionInto(NF, &F, Map, true, Returns, "Cloned");

 

The code seems to work as intended, but when we try to emit debug symbols (clang -g flag) the pass fails with following message:

"All DICompileUnits must be listed in llvm.dbg.cu <http://llvm.dbg.cu/> "

 

Nevertheless, we can dump the Module and therefore can print out the annotated IR.

 

This is what the function to be cloned looks like:

 

; Function Attrs: noinline nounwind uwtable

define linkonce_odr void @_ZN12MyFunnyClassC2Ev(%struct.MyFunnyClass* %this) unnamed_addr #4 comdat align 2 !dbg !46 {

entry:

  %this.addr = alloca %struct.MyFunnyClass*, align 8

  store %struct.MyFunnyClass* %this, %struct.MyFunnyClass** %this.addr, align 8

  call void @llvm.dbg.declare(metadata %struct.MyFunnyClass** %this.addr, metadata !49, metadata !31), !dbg !50

... rest of function code

}

 

!46 = distinct !DISubprogram(name: "MyFunnyClass", linkageName: "_ZN12MyFunnyClassC2Ev", scope: !15, file: !1, line: 1, type: !25, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false, unit: !0, declaration: !47, variables: !2)

 

and the cloned function:

 

; Function Attrs: noinline nounwind uwtable

define linkonce_odr void @_ZN12MyFunnyClassC2EvCloned(%struct.MyFunnyClass* %this, { [6 x i8*] }* %newparam) unnamed_addr #4 align 2 !dbg !73 {

entry:

  %this.addr = alloca %struct.MyFunnyClass*, align 8

  store %struct.MyFunnyClass* %this, %struct.MyFunnyClass** %this.addr, align 8

  call void @llvm.dbg.declare(metadata %struct.MyFunnyClass** %this.addr, metadata !89, metadata !31), !dbg !91

... rest of function code

}

 

!73 = distinct !DISubprogram(name: "MyFunnyClass", linkageName: "_ZN12MyFunnyClassC2Ev", scope: !74, file: !1, line: 1, type: !81, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false, unit: !87, declaration: !88, variables: !2)

 

So the cloned function gets annotated with debug symbols as expected. We noticed that the linkageName of the cloned function is the same as the original one's. Could that cause the error mentioned above? If so, how can we fix that error?

 

Best regards and thanks in advance,

Matthias

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