[llvm-dev] Slow IR compilation/JIT, profiling points to LLVM?

[edA-qa mort-ora-y via llvm-dev]

I'll post the fragments of code below related to setup/exec.  I
double-checked the object file generation and that appears to be a lot
better now, around only 2% total time (time in ld is very high, but I
guess that's not LLVM's responsibility).  This has changed recently I
think, it used to be higher. Nonetheless, let's look at the JIT (or not
JIT) for now).

I use the execution engine:

    std::string errStr;
     llvm::EngineBuilder builder{ unique_ptr<llvm::Module>(module) };
    llvm::ExecutionEngine * ee = builder.
        setErrorStr( &errStr ).
        setEngineKind( llvm::EngineKind::JIT ).
        setTargetOptions( topts ).
        create();

    ee->finalizeObject();
    auto main = ee->FindFunctionNamed( "main" );
    STATE_CHECK( main, "missing-main" );
   
    std::vector<llvm::GenericValue> args(2);
    args[0].IntVal = llvm::APInt( platform::target->abi_int_size, 0 );
    args[1].PointerVal = nullptr;
    llvm::GenericValue gv = ee->runFunction( main, args );
    auto ret = int(gv.IntVal.getSExtValue());
    delete ee;
    return ret;



In case relevant, this is how I setup the module/context:

    llvm::InitializeNativeTarget();
    llvm_context.reset( new llvm::LLVMContext );
    module = new llvm::Module( "test", *llvm_context );
    module->setTargetTriple( platform::target->triple );
    del_module = true;
   
    std::string err_str;
    auto triple_str = llvm::Triple::normalize(platform::target->triple);
    llvm::Target const *  target = llvm::TargetRegistry::lookupTarget(
triple_str, err_str );
    STATE_CHECK( target, err_str );
    auto targetMachine = target->createTargetMachine(triple_str,
"generic", "", llvm::TargetOptions{},
        llvm::Optional<llvm::Reloc::Model>());
   
    module->setDataLayout( targetMachine->createDataLayout() );



Versions:
LLVM 6.0.0
GCC 5.4.0
(K)Ubuntu 16.04

On 05/05/18 09:51, Alex Denisov wrote:
> Hi,
>
> Could you share how you compile IR and which version of JIT you use (Orc, MCJIT)?
> Could it be that you are using interpreter instead of actual JIT?
>
> Cheers,
> Alex.
>
>> On 5. May 2018, at 08:04, edA-qa mort-ora-y via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>>
>> I'm having issues of my compiler, and JIT execution, of LLVM IR being
>> rather slow. It's accounting for the vast majority of my full
>> compilation time.  I'm trying to figure out why this is happening, since
>> it's becoming an impediment.  (Note: by slow I mean about 3s of time for
>> only about 2K of my front-end code, 65K lines of LLVM-IR)
>>
>>
>> Using valgrind I see some functions which seem out of place and
>> accounting for the vast majority of the time.
>>
>>     5.72%; 635,008 Calls; llvm::PMTopLevelManager::findAnalysisPass(void
>> const*) <cycle 4>
>>
>>     4.54%; 3,722,489 Calls; llvm::PMDataManager::findAnalysisPass(void
>> const*, bool)'2
>>
>>     4.11%; 4,604,499 Calls; bool
>> llvm::DenseMapBase<>::LookupBucketFor<>(void const* const&,
>> llvm::detail::DenseMapPair<> const*&) const
>>
>> Also of interest, given the high call count:
>>
>>     1.32%; 6,915,882 Calls; llvm::FoldingSetNodeID::AddInteger(unsigned
>> int) <cycle 4>
>>
>> The call counts seem quite high given the size of the code. Also, the
>> `findAnalysisPass` function just seems off, but I don't understand
>> LLVM's architecture to be sure.
>>
>>
>> Could this be pointing to something I'm doing wrong in my LLVM setup, or
>> is it just slow?
>>
>>
>> I'm reasonably certain I'm compiling LLVM in optimized mode, but for
>> reference, this is my build line:
>>
>>     cmake .. -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_EH=ON
>> -DLLVM_ENABLE_RTTI=ON -DLLVM_REQUIRES_RTTI=ON -DLLVM_ENABLE_CXX1Y=ON
>> -DLLVM_LINK_LLVM_DYLIB=ON -DLLVM_ENABLE_FFI=ON
>> -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_OPTIMIZED_TABLEGEN=ON
>> -DCMAKE_INSTALL_PREFIX="/opt/llvm/install"
>>
>>
>> The overall time split, from valgrind, between shared libraries in my
>> code is:
>>
>>     80.48%, libLLVM-6.0.so
>>     8.83% libc-2.23.so
>>     2.34% libleaf_lang.so (my front-end)
>>
>> --
>> edA-qa mort-ora-y
>> 	http://mortoray.com/
>>
>> Creator of the Leaf language
>> 	http://leaflang.org/
>>
>> Streaming algorithms, AI, and design on Twitch
>> 	https://www.twitch.tv/mortoray
>>
>> Twitter
>> 	edaqa
>>
>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev


-- 
edA-qa mort-ora-y  
	http://mortoray.com/

Creator of the Leaf language
	http://leaflang.org/

Streaming algorithms, AI, and design on Twitch
	https://www.twitch.tv/mortoray

Twitter
	edaqa
	


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