Re: [xmlvm-users] JVM to LLVM or XMLVM to LLVM

[Arno P. <ar...@pu...>]

I think this is definitely a good idea. What you are proposing is a Java 
frontend to LLVM. There seems to be at least one such project:
https://llvm.org/svn/llvm-project/java/trunk/docs/java-frontend.txt

Reading through that page, they discuss some difficulties in modeling 
the operand stack of the JVM. It might be interesting to investigate a 
DEX frontend to LLVM since it uses a register-based instruction set 
(XMLVM also uses DEX for the C backend). A cursory search didn't show 
any hits.

Arno


On 9/10/13 4:45 AM, Steve Hannah wrote:
> Hi Arno et al.,
>
> I'm curious if anyone has considered writing an XMLVM converter to go
> from JVM byte code to LLVM?  I have been analyzing the java to c path,
> then compiled the resulting C code to LLVM IR code and compared that IR
> code to the original JVM bytecode instructions.
>
> On a cursory review of some methods I have found that the IR code
> generally contains about 10 times the number of instructions as the
> corresponding JVM byte code.  This factor also corresponds closely with
> the benchmark results comparing Oracle's JVM to XMLVM (using some JSON
> parsing tests I have set up).
>
> I'm thinking that optimal results can probably be attained with there is
> roughly a 1 to 1 correspondence between JVM instructions and LLVM
> instructions.
>
> It seems to me that XMLVM is well suited for being able to output LLVM,
> but I'm sort of just thinking out loud at this point.
>
> Has this been thought of or tried by anyone yet?  Is my goal of seeking
> a 1 to 1 mapping of JVM instructions to LLVM instructions (or as close
> as possible) as a means of performance maximization off base?  Are there
> technical reasons why such a conversion either can't be done or would
> not be useful?
>
> Thanks for any insight you can provide.
>
> Best regards
>
> Steve
>
> --
> Steve Hannah
> Web Lite Solutions Corp.
>
>
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