[swift-dev] DebugScope Verification Error

[Vedant Kumar]

+ Adrian and Davide, since they work in this area.

Hi Raj,

> On Jan 15, 2018, at 4:48 PM, Raj Barik via swift-dev <swift-dev at swift.org> wrote:
> 
> Thanks Mark. You are right, the following assertion fails
> 
> require(!DS || DS->getParentFunction() == I->getFunction(),
>             "debug scope of instruction belongs to a different function");
> 
> I am not sure if we need such a check.

This check exists to ensure that the debug info generated for a program is helpful. For example, a function with the wrong debug scope attached might make for confusing backtraces.

vedant

>   
> 
> On Mon, Jan 15, 2018 at 4:16 PM, Mark Lacey <mark.lacey at apple.com <mailto:mark.lacey at apple.com>> wrote:
> 
> 
>> On Jan 15, 2018, at 12:54 PM, Raj Barik <rkbarik at gmail.com <mailto:rkbarik at gmail.com>> wrote:
>> 
>> Mark,
>> 
>> Thanks a lot for quick reply.
>>  
>> Is there any reason this interface in SILInstruction should be private?
>> void setDebugScope(SILBuilder &B, const SILDebugScope *DS);
>> 
>> In my case, I am splicing the old F into the new function NF. While splicing retains the debug scope, the new instruction (InitRef) that I am adding to NF is being created in some random scope (not F) even though I explicitly make Builder's debug scope point to F's. 
> 
> The assert you originally hit appears to indicate that the parentFunction of the debug scope for an instruction should be the same as the function the instruction is in. I am not very familiar with the requirements of our debug information and debug scopes, but this seems like a reasonable expectation.
> 
> I suggested looking at SILCloner because it is the primary way by which we clone functions, and clearly has to deal with debug scopes when it does so.
> 
> I’m not sure how much more help I can be on this matter, but perhaps someone more knowledgable can chime in.
> 
> Mark
> 
> 
> 
> 
>> 
>> Best,
>> Raj
>> 
>> 
>> 
>> On Mon, Jan 15, 2018 at 9:52 AM, Mark Lacey <mark.lacey at apple.com <mailto:mark.lacey at apple.com>> wrote:
>> I’d suggest looking at SILCloner.h as well as ScopeCloner in SILBasicBlock.cpp to see how they are dealing with debug scopes.
>> 
>> Mark
>> 
>> > On Jan 15, 2018, at 9:24 AM, Raj Barik via swift-dev <swift-dev at swift.org <mailto:swift-dev at swift.org>> wrote:
>> >
>> > Hi,
>> >
>> > I am running into a debug scope SIL Verifier error when creating a new function (NF) from an existing one (F). Can someone point me where I am going wrong?
>> >
>> > NF = M.createFunction(...., F->getDebugScope());
>> > SILBasicBlock *NFBody = NF->createBasicBlock();
>> > SILBuilder NFBuilder(NFBody);
>> > SILOpenedArchetypesTracker OpenedArchetypesTrackerNF(NF);
>> > NFBuilder.setOpenedArchetypesTracker(&OpenedArchetypesTrackerNF);
>> > NFBuilder.setCurrentDebugScope(NFBody->getParent()->getDebugScope());
>> > ...
>> > for (auto &param : params) { /* Assume all are generic types */
>> >   auto GenericsSILType = ....
>> >   auto NewArg = NFBody->createFunctionArgument(GenericSILType);
>> >   auto Conformances = Mod->lookupConformance(...);
>> >   auto *InitRef = NFBuilder.createInitExistentialRef( Loc, ArgDesc.Arg->getType(), NewArg->getType().getSwiftRValueType()->getCanonicalType(), NewArg, Conformances);
>> >   ...
>> > }
>> >
>> > The InitRef instruction created above runs into SIL verifier error:
>> >
>> > SIL verification failed: debug scope of instruction belongs to a different function: !DS || DS->getParentFunction() == I->getFunction()
>> > Verifying instruction:
>> >    %0 = argument of bb0 : $τ_0_0                 // user: %1
>> > ->   %1 = init_existential_ref %0 : $τ_0_0 : $τ_0_0, $SomeProtocol // user: %2
>> >
>> > The SIL looks correct to me though.
>> >
>> > --Raj
>> > _______________________________________________
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>> > swift-dev at swift.org <mailto:swift-dev at swift.org>
>> > https://lists.swift.org/mailman/listinfo/swift-dev <https://lists.swift.org/mailman/listinfo/swift-dev>
>> 
>> 
> 
> 
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