[LLVMdev] JIT compilation 2-3 times slower in latest LLVM snapshot

[Dibyendu Majumdar]

On 11 July 2015 at 12:45, Dibyendu Majumdar <mobile at majumdar.org.uk> wrote:
> I updated my clone of the LLVM github mirror today and I am finding
> that the JIT compilation is now 2-3 times slower. The last time I
> refreshed was maybe 2 weeks ago. Is there a known change that would
> explain this?
>
> This is on Windows 8.1 64-bit. I am using MCJIT.
>

To give you some idea:

On Linux VM running on the same machine, using LLVM 3.6.1, the time
taken for my test:

../build/lua -e"_U=true;ravi.optlevel(2); ravi.auto(true,1)" all.lua
total time: 70.80s (wall time: 73s)

On Windows natively running against latest LLVM snapshot:

..\build\Release\lua.exe -e"_U=true; ravi.optlevel(2);
ravi.auto(true,1)" all.lua
total time: 333.65s (wall time: 333s)

My benchmarks run fine hence my view that it is taking longer to JIT
rather than an issue with the generated code.

Unfortunately I don't have the timing I was getting previously but
from memory it was roughly similar to the Linux timing above.

Thanks and Regards
Dibyendu