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

[Alex Denisov via llvm-dev]

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
> 
> 
> 
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