[llvm] r277257 - [Orc] Add support for updating stub targets to CompileOnDemandLayer.

[Lang Hames via llvm-commits]

Hi Dave,

Why is the C binding the best path to testing this? That seems
> strange/surprising to me. (would expect it'd be testable via the C++ API in
> a more narrow way sooner/without as much other infrastructure)


Actually we could add a test to the CompileOnDemandLayer tests that
"updatePointer" returns true for a symbol that has been added, and false
otherwise.

To actually test the behavior though we need an execution test. Since
execution unit tests have a higher maintenance burden (can only be run on
certain platforms, require a fully working stack) we only maintain one: the
C Bindings Stack unit test.

- Lang.

On Mon, Aug 1, 2016 at 9:28 AM, David Blaikie <dblaikie at gmail.com> wrote:

>
>
> On Fri, Jul 29, 2016 at 6:05 PM Lang Hames via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: lhames
>> Date: Fri Jul 29 19:57:54 2016
>> New Revision: 277257
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=277257&view=rev
>> Log:
>> [Orc] Add support for updating stub targets to CompileOnDemandLayer.
>>
>> This makes it possible to implement re-optimization on top of the
>> CompileOnDemandLayer.
>>
>> Test case to come in a future patch: This will need an execution test, and
>> execution tests require a full working stack. The best option is to plumb
>> this
>> API up to the C Bindings stack and add a C bindings test for this.
>>
>
> Why is the C binding the best path to testing this? That seems
> strange/surprising to me. (would expect it'd be testable via the C++ API in
> a more narrow way sooner/without as much other infrastructure)
>
>
>>
>> Patch by Sean Ogden. Thanks Sean!
>>
>>
>> Modified:
>>     llvm/trunk/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h
>>     llvm/trunk/include/llvm/ExecutionEngine/Orc/LogicalDylib.h
>>
>> Modified:
>> llvm/trunk/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h?rev=277257&r1=277256&r2=277257&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h
>> (original)
>> +++ llvm/trunk/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h
>> Fri Jul 29 19:57:54 2016
>> @@ -236,6 +236,32 @@ public:
>>      return H->findSymbol(Name, ExportedSymbolsOnly);
>>    }
>>
>> +  /// @brief Update the stub for the given function to point at
>> FnBodyAddr.
>> +  /// This can be used to support re-optimization.
>> +  /// @return true if the function exists and the stub is updated, false
>> +  ///         otherwise.
>> +  //
>> +  // FIXME: We should track and free associated resources (unused compile
>> +  //        callbacks, uncompiled IR, and no-longer-needed/reachable
>> function
>> +  //        implementations).
>> +  // FIXME: Return Error once the JIT APIs are Errorized.
>> +  bool updatePointer(std::string FuncName, TargetAddress FnBodyAddr) {
>> +    //Find out which logical dylib contains our symbol
>> +    auto LDI = LogicalDylibs.begin();
>> +    for (auto LDE = LogicalDylibs.end(); LDI != LDE; ++LDI) {
>> +      if (auto LMResources =
>> LDI->getLogicalModuleResourcesForSymbol(FuncName, false)) {
>> +        Module &SrcM = LMResources->SourceModule->getResource();
>> +        std::string CalledFnName = mangle(FuncName,
>> SrcM.getDataLayout());
>> +        if (auto EC = LMResources->StubsMgr->updatePointer(CalledFnName,
>> FnBodyAddr)) {
>> +          return false;
>> +        }
>> +        else
>> +          return true;
>> +      }
>> +    }
>> +    return false;
>> +  }
>> +
>>  private:
>>
>>    template <typename ModulePtrT>
>>
>> Modified: llvm/trunk/include/llvm/ExecutionEngine/Orc/LogicalDylib.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ExecutionEngine/Orc/LogicalDylib.h?rev=277257&r1=277256&r2=277257&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/ExecutionEngine/Orc/LogicalDylib.h (original)
>> +++ llvm/trunk/include/llvm/ExecutionEngine/Orc/LogicalDylib.h Fri Jul 29
>> 19:57:54 2016
>> @@ -123,6 +123,16 @@ public:
>>
>>    LogicalDylibResources& getDylibResources() { return DylibResources; }
>>
>> +  LogicalModuleResources*
>> +  getLogicalModuleResourcesForSymbol(const std::string &Name,
>> +                                     bool ExportedSymbolsOnly) {
>> +    for (auto LMI = LogicalModules.begin(), LME = LogicalModules.end();
>> +         LMI != LME; ++LMI)
>> +      if (auto Sym = LMI->Resources.findSymbol(Name,
>> ExportedSymbolsOnly))
>> +        return &LMI->Resources;
>> +    return nullptr;
>> +  }
>> +
>>  protected:
>>    BaseLayerT BaseLayer;
>>    LogicalModuleList LogicalModules;
>>
>>
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>>
>
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