[llvm] r221742 - Extend intrinsic name mangling to support arrays, named structs, and function types.

[Sean Silva]

On Tue, Nov 11, 2014 at 4:42 PM, Philip Reames <listmail at philipreames.com>
wrote:

>
> On 11/11/2014 04:33 PM, Sean Silva wrote:
>
>  Can you please beef up the comment to give a declarative/human-readable
> description of the mangling scheme?
>
> Sure.  Will address in a follow up commit.  (Without further review unless
> you object.)
>

Go for it.


>
>
>  Also, would it make sense to document this mangling in LangRef?
>
> It is currently not documented.   I don't have a strong opinion, but would
> lean towards not documenting it.  It's arguably an internal implementation
> detail.   There's enough rough edges around this mechanism that I'm really
> reluctant to encourage it's use, except through the programmatic APIs.
> (For example, if you get the naming wrong, it's a silent codegen problem.
> This is not new.)
>

Makes sense.

-- Sean Silva


>
> For context, there's discussion of removing this mechanism entirely since
> it makes the code much harder to read.  That change (which might include
> special casing type rules around intrinsics) will definitely need broader
> review and documentation.
>
>
>
>  One nit:
>
>  +    Result += "f"; //ensure distinguishable
>
> "... use proper capitalization, punctuation, etc ...."
> http://llvm.org/docs/CodingStandards.html#commenting
>
> Will fix in follow up.
>
>
>  -- Sean Silva
>
> On Tue, Nov 11, 2014 at 4:21 PM, Philip Reames <listmail at philipreames.com>
> wrote:
>
>> Author: reames
>> Date: Tue Nov 11 18:21:51 2014
>> New Revision: 221742
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=221742&view=rev
>> Log:
>> Extend intrinsic name mangling to support arrays, named structs, and
>> function types.
>>
>> Currently, we have a type parameter mechanism for intrinsics. Rather than
>> having to specify a separate intrinsic for each combination of argument and
>> return types, we can specify a single intrinsic with one or more type
>> parameters. These type parameters are passed explicitly to
>> Intrinsic::getDeclaration or can be specified implicitly in the naming of
>> the intrinsic function in an LL file.
>>
>> Today, the types are limited to integer, floating point, and pointer
>> types. With a goal of supporting symbolic targets for patchpoints and
>> statepoints, this change adds support for function types.  The change also
>> includes support for first class aggregate types (named structures and
>> arrays) since these appear in function types we've encountered.
>>
>> Reviewed by: atrick, ributzka
>> Differential Revision: http://reviews.llvm.org/D4608
>>
>>
>> Modified:
>>     llvm/trunk/lib/IR/Function.cpp
>>
>> Modified: llvm/trunk/lib/IR/Function.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Function.cpp?rev=221742&r1=221741&r2=221742&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/IR/Function.cpp (original)
>> +++ llvm/trunk/lib/IR/Function.cpp Tue Nov 11 18:21:51 2014
>> @@ -455,6 +455,33 @@ unsigned Function::lookupIntrinsicID() c
>>    return 0;
>>  }
>>
>> +/// Returns a stable mangling for the type specified for use in the name
>> +/// mangling scheme used by 'any' types in intrinsic signatures.
>> +static std::string getMangledTypeStr(Type* Ty) {
>> +  std::string Result;
>> +  if (PointerType* PTyp = dyn_cast<PointerType>(Ty)) {
>> +    Result += "p" + llvm::utostr(PTyp->getAddressSpace()) +
>> +      getMangledTypeStr(PTyp->getElementType());
>> +  } else if (ArrayType* ATyp = dyn_cast<ArrayType>(Ty)) {
>> +    Result += "a" + llvm::utostr(ATyp->getNumElements()) +
>> +      getMangledTypeStr(ATyp->getElementType());
>> +  } else if (StructType* STyp = dyn_cast<StructType>(Ty)) {
>> +    if (!STyp->isLiteral())
>> +      Result += STyp->getName();
>> +    else
>> +      llvm_unreachable("TODO: implement literal types");
>> +  } else if (FunctionType* FT = dyn_cast<FunctionType>(Ty)) {
>> +    Result += "f_" + getMangledTypeStr(FT->getReturnType());
>> +    for (size_t i = 0; i < FT->getNumParams(); i++)
>> +      Result += getMangledTypeStr(FT->getParamType(i));
>> +    if (FT->isVarArg())
>> +      Result += "vararg";
>> +    Result += "f"; //ensure distinguishable
>> +  } else if (Ty)
>> +    Result += EVT::getEVT(Ty).getEVTString();
>> +  return Result;
>> +}
>> +
>>  std::string Intrinsic::getName(ID id, ArrayRef<Type*> Tys) {
>>    assert(id < num_intrinsics && "Invalid intrinsic ID!");
>>    static const char * const Table[] = {
>> @@ -467,12 +494,7 @@ std::string Intrinsic::getName(ID id, Ar
>>      return Table[id];
>>    std::string Result(Table[id]);
>>    for (unsigned i = 0; i < Tys.size(); ++i) {
>> -    if (PointerType* PTyp = dyn_cast<PointerType>(Tys[i])) {
>> -      Result += ".p" + llvm::utostr(PTyp->getAddressSpace()) +
>> -                EVT::getEVT(PTyp->getElementType()).getEVTString();
>> -    }
>> -    else if (Tys[i])
>> -      Result += "." + EVT::getEVT(Tys[i]).getEVTString();
>> +    Result += "." + getMangledTypeStr(Tys[i]);
>>    }
>>    return Result;
>>  }
>>
>>
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>
>
>
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