[LLVMdev] Very slow performance of lli on x86

[Evan Cheng]

He is probably using the interpreter on a debug build.

Evan

On Nov 14, 2009, at 1:40 PM, Eric Christopher <echristo at apple.com>  
wrote:

>>
>> for -O3 results refer attachment.
>> time                      clang (- 
>> O0)                                 llvm-gcc(-O0)                    
>> gcc(-O0)
>> real                       
>> 0m10.247s                                    
>> 0m11.324s                         0m10.963s
>> user                      
>> 0m2.644s                                      
>> 0m2.478s                          0m2.263s
>> sys                       
>> 0m5.949s                                      
>> 0m6.000s                          0m5.953s
>>
>> llvm-jit
>> i used clang-cc -O0 -emit-llvm-bc to emit llvm bytecode and then  
>> passed it to opt tool and then linked all bytecode files to single  
>> bytecode using llvm-ld, i used lli tool to run this single bytecode  
>> file and noticed the following output
>> real      6m33.786s
>> user      5m12.612s
>> sys       1m1.205s
>>
>> why is lli taking such a loooong time to execute this particular  
>> piece of code.??
>
> Something's wrong on your machine or something. I did the same (but  
> using llvm-gcc for the .ll files).  Using a debug build of current  
> ToT I got this:
>
> [ghostwheel:~/Desktop] echristo% time ~/builds/build-llvm-64bit/ 
> Debug/bin/lli foo.bc.bc
> 0.210u 0.010s 0:00.22 100.0%    0+0k 0+0io 0pf+0w
>
>
> That's a 64-bit build, but you'll notice the time difference. That  
> said I'm guessing that there's something missing since it takes no  
> time to execute. Step by step directions on what you did might help.
>
> -eric
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev