Id�es pour l'IR de Photon  3 aout 2011
-------------------------


E ::= let V = LETOP in E

   |  if IFOP then E else E

   |  iflet V = IFLETOP then E else E

   |  goto V(P,...)     ;; the dynamic type of V is "block"

   |  call V(P,...)     ;; the dynamic type of V is "function"

   |  return V(P,...)   ;; the dynamic type of V is "continuation"

    
V ::= <variable>


C ::= <number> | <boolean> | <string> | null | undefined | global | handler


P ::= C
   |  V
   |  block(V,...) { E }
   |  function(V,...) { E }
   |  continuation(V,...) { E }


LETOP   ::= P
         |  get_prop(P_1,P_2)
         |  put_prop(P_1,P_2,P_3)
         |  del_prop(P_1,P_2)
         |  fix_add_wrap(P_1,P_2)
         |  fix_sub_wrap(P_1,P_2)
         |  fix_mul_wrap(P_1,P_2)
         |  fix_div_wrap(P_1,P_2)
         |  let_prim(<string>,P,...)


IFOP    ::= is_fix(P)
         |  fix_eq(P_1,P_2)
         |  fix_lt(P_1,P_2)
         |  fix_le(P_1,P_2)
         |  fix_gt(P_1,P_2)
         |  fix_ge(P_1,P_2)
         |  is_flo(P)
         |  flo_eq(P_1,P_2)
         |  flo_lt(P_1,P_2)
         |  flo_le(P_1,P_2)
         |  flo_gt(P_1,P_2)
         |  flo_ge(P_1,P_2)
         |  is_false(P)
         |  if_prim(<string>,P,...)


IFLETOP ::= fix_add_no_ovf(P_1,P_2)
         |  fix_sub_no_ovf(P_1,P_2)
         |  fix_mul_no_ovf(P_1,P_2)
         |  fix_div_no_ovf(P_1,P_2)
         |  iflet_prim(<string>,P,...)


Exemples:


#1:

var z = f(1);

compiles to:

block(ret)
{
  let t1 = get_prop(global,"f") in
    let c = continuation(r)
            { let t2 = put_prop(global,"z",r) in
                return ret(undefined) } in
      call t1(c,1)
}


#2:

var z = x + y;

compiles to:

block(ret)
{
  let t1 = let_prim("js_get_prop",global,"x") in
    let t2 = let_prim("js_get_prop",global,"y") in
      let r = let_prim("js_add",t1,t2) in
        let t3 = let_prim("js_put_prop",global,"z",r) in
          return ret(undefined)
}


#3:

var z = x + y;

compiles to:

block(ret)
{
  let t1 = get_prop(global,"x") in
    let t2 = get_prop(global,"y") in
      let b1 = block(r) { let t3 = put_prop(global,"z",r) in
                            return ret(undefined) } in
        let b2 = block() { let t4 = get_prop(handler,"gen_add") in
                             let c = continuation(r2) { goto b1(ret,r2) } in
                               call t4(c,t1,t2) } in
          if is_fix(t1) then
            if is_fix(t2) then
              iflet t5 = fix_add_no_ovf(t1,t2) then
                goto b1(ret,t5)
              else
                goto b2(ret)
            else
              goto b2(ret)
          else
            goto b2(ret)
}


Quelques exemples de r�gles de compilation:


1) exemple simple

let V = let_prim("js_get_prop",X,Y) in Z
=>
let V = get_prop(X,Y) in Z


2) exemple avec annotations de type

let V = let_prim("js_add",X:any,Y:any) in Z
=>
let b = block() { let V:any = let_prim("js_add_gen",X,Y) in Z } in
  if is_fix(X) then
    if is_fix(Y) then
      iflet V:fix = fix_add_no_ovf(X,Y) then
        Z
      else
        goto b()
    else
      goto b()
  else
    goto b()


3) exemple avec annotations de type plus fines

let V = let_prim("js_add",X:fix,Y:fix) in Z
=>
let b = block() { let V:any = let_prim("js_add_gen",X,Y) in Z } in
  iflet V:fix = fix_add_no_ovf(X,Y) then
    Z
  else
    goto b()