perl5-jit-plan.md

Perl5: method based tracing for JIT (just in time complation)

During the execution:

• Trace and collect the argument types for the method and the return value type. (some method returns mixed type variable, we should ignore that kind of the method)
• Add the type signature to the method, each type signature refers to the compiled machine code.
• Calculate the execution times of a method and see if it exceeds the threshold.

When compiling a method, the compiler:

• Will be given a method, and the compiler generates the corresponding compiled machine code for each type signature.
• The compiled method should base on the argument types. (that is, type signature, e.g. [int, int] => [int])

When compiling:

sub square { my ($a, $b) = @_; return $a * $b; }

• For the runtime system, we need to know the variable address, the address of the stack...

• Just use the machine stack (not the perl's runtime stack) to push arguments before calling a compiled method, for example, when compiling:

    square(3,5);
  

  we compile it to:

    ; push arguments to the machine stack
    movl eax, resolve_int_address_for_scalar($b)
    push eax
    movl eax, resolve_int_address_for_scalar($a)
    push eax
    call [square:int=int,int]
    movl [scalar address for return value], eax
  

• And the instructions in the compiled method will do:

    ; prolog
    push ebp
    movl ebp, esp
  
    movl eax, [ebp-4]
    imul eax, [ebp-8]
  
    ; epilog
    pop ebp
    ret
  

Update:

gist --update https://gist.github.com/27533f296523d290e0af perl5-jit-plan.md