[cfe-dev] [LLVMdev] Very slow performance of lli on x86
echristo at apple.com
Sat Nov 14 15:40:40 CST 2009
> 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
> 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.
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