SSE and MMX support in the JIT compiler

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Andre - 30 Jul 2003 07:06 GMT

Hi,

I was wondering if anyone knows whether the JIT compiler supports
SSE/SSE2 instructions? Thanks

-Andre

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David Notario - 02 Aug 2003 06:06 GMT

We currently use SSE2 for some things like the double to int cast, it's not
used for general codegen though.

Signature

David Notario
Software Design Engineer - CLR JIT Compiler

> Hi,
>
> I was wondering if anyone knows whether the JIT compiler supports
> SSE/SSE2 instructions? Thanks
>
> -Andre

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Andre - 02 Aug 2003 10:10 GMT

Thanks David,

There's one thing I need to ask you - were there a fair amount of
features/improvements in ver1.1 of the CLR compared to v1.0? I see that
total numebr of bytes JIT'd are noticeably less in ver1.1 and some
profiling showed that ver1.1 gave better MFLOPs in executing some
benchmarking code. Thanks

-Andre

> We currently use SSE2 for some things like the double to int cast, it's not
> used for general codegen though.

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David Notario - 05 Aug 2003 03:10 GMT

No, we didn't do much optimization work in the JIT for v1.1, except for some
very targetted ones that offered a significant speed boost in exchange for
little dev work (1.1 was mainly a security fixes only release for the CLR),
such as the double to int cast (40x speed increase by just using SSE2
instruction)

Signature

David Notario
Software Design Engineer - CLR JIT Compiler

> Thanks David,
>
[quoted text clipped - 8 lines]
> > We currently use SSE2 for some things like the double to int cast, it's not
> > used for general codegen though.

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David Notario - 05 Aug 2003 03:21 GMT

Where I say security fixes for the CLR, I mean for the JIT, there were perf
improvements in other areas different than the JIT

Signature

David Notario
Software Design Engineer - CLR JIT Compiler

> No, we didn't do much optimization work in the JIT for v1.1, except for some
> very targetted ones that offered a significant speed boost in exchange for
[quoted text clipped - 15 lines]
> not
> > > used for general codegen though.

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Andre - 05 Aug 2003 09:08 GMT

Thanks David,

> No, we didn't do much optimization work in the JIT for v1.1, except for some
> very targetted ones that offered a significant speed boost in exchange for
> little dev work (1.1 was mainly a security fixes only release for the CLR),
> such as the double to int cast (40x speed increase by just using SSE2
> instruction)

So does that mean v1.0 didn't use SSE2 at all (and only used SSE?)? I
guess that's just why I see an increase in the number of FLOPS using v1.1.

If optimizations are being targetted to a particular platform.. does
that imply that there are other platforms .NET is being ported to? (I'm
only aware of Mono and that's on a x86) Does Microsoft plan on porting
.NET (or allow others) to Sun or any other platform for instance?

You mentioned that there have been some improvement in areas other than
the JIT.. could you name some? I'm trying to write up a report for my
company to convince them to completely switch to .NET from J2EE/J2SE and
for that I need to have solid reasoning and give accurate measurements
to show improvements in CLR v1.1 over v1.0. After a months study I'm
personally convinced that the CLR will improve (and some very
interesting features are being added to C# in the next release).. I
can't seem to find anything documented on the current implementation of
the CLR and Rotor, for that matter, is simply not worth studying (as the
optimizing compiler has bee stripped off from it). It would really help
me if you could shed a little more light on this please. Thanks again
for your time David,

-Andre

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SSE and MMX support in the JIT compiler

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