[llvm-dev] CloneFunctionInto produces invalid debug info

[David Blaikie via llvm-dev]

+Adrian

On Thu, Jun 15, 2017 at 9:25 AM Sergei Larin via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> We are seeing the same. Cloning is failing to add newly created
> DICompileUnit to llvm.dbg.cu in the module resulting in verifier assert.
>
>
>
> Sergei
>
>
>
> *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] *On Behalf Of *Matthias
> Bernad via llvm-dev
> *Sent:* Thursday, June 15, 2017 10:32 AM
> *To:* llvm-dev at lists.llvm.org
> *Subject:* [llvm-dev] CloneFunctionInto produces invalid debug info
>
>
>
> 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"
>
>
>
> 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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