llvm dev - Jul 2015 - [LLVMdev] JIT compilation 2-3 times slower in latest LLVM snapshot

Hi

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.

Thanks and Regards
Dibyendu

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

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu]
> On Behalf Of Dibyendu Majumdar
> Subject: [LLVMdev] JIT compilation 2-3 times slower in latest LLVM snapshot
> 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?
Debug+Asserts build rather than Release (or Release+Asserts)?

 - Chuck

On 11 July 2015 at 13:14, Caldarale, Charles R
<Chuck.Caldarale at unisys.com> wrote:
>> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu]
>> On Behalf Of Dibyendu Majumdar
>> Subject: [LLVMdev] JIT compilation 2-3 times slower in latest LLVM
snapshot
>
>> 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?
>
> Debug+Asserts build rather than Release (or Release+Asserts)?
>
I haven't changed my build - it is a Release build. Have the settings
in the Released build has changed recently?

Regards