Re: [DotGNU]Morphing java code to IL

[Gopal V]

Hi,

> You don't want to do this.  Trust me.  JVM bytecode
> is very different in structure to IL, even though it looks
> similar.  Local variables are the hardest.  IL explicitly
> tags locals with their types.  JVM doesn't - the type
> is determined by looking for the first place in the
> method where the variable is assigned.

  I had prepared a comparison of the JVM opcodes and IL opcodes
  and come to the conculsion that they were comparable. JVM 
  opcodes have an equivalent or similar opcode in IL. So I 
  thought that JVM => IL was possible. Frankly the idea of 
  local variables creating problems did not cross my mind.  
 
 

> However, do not attempt to convert the bytecodes into
> IL.  Instead, just return the raw code to the caller.  It is
> the responsibility of the caller, such as the disassembler,
> to interpret the bytecodes appropriately.  I've been
> planning for some time to add Java method bodies to
> ilasm and ildasm.  I actually want it to work this way,
> to support the C# compiler's JVM mode.

  I think this makes more sense why I should not convert during
  loading.  
> If you really want to build a JVM->IL converter, then
> do it as a separate program.  It would call the function
> ILMethodGetCode to get the Java method body, and
> then would perform dynamic flow analysis to figure out
> the local variables prior to conversion.  But be warned:
> it is a _lot_ harder than it looks.
> 
  With the problem of typed local variables , I would have to do a 
  reshuffling of local variables to get the correct type onto the
  correct local var. But can I change type flag of a local variable
  using some opcode (is there any such thing ?).

Gopal