Re: LuaJIT roadmap 2008 question

[Mike Pall <mikelu-0910@...>]

tankxx wrote:
> The calling convention is so well designed that using the function
> slot inplace. May you post the code snippets about frame handling that
> corresponding ldo.c?
> I want to dig into the details about all kinds of frame links. :)

Well, it's heavily-macroized assembler ... but here you go:

  |->gate_lf:                           // Call gate for fixarg Lua functions.
  |  // RA = new base, RB = LFUNC, RC = nargs+1, (BASE = old base), PC = return
  |  // DISPATCH initialized
  |  mov BASE, RA
  |  mov PROTO:RB, LFUNC:RB->pt
  |  mov [BASE-4], PC                   // Store caller PC.    <=== !!
  |  movzx RA, byte PROTO:RB->framesize
  |  mov PC, PROTO:RB->bc
  |  mov KBASE, PROTO:RB->k
  |  mov L:RB, SAVE_L
  |  lea RA, [BASE+RA*8]                // Top of frame.
  |  lea RC, [BASE+NARGS:RC*8-4]        // Points to tag of 1st free slot.
  |  cmp RA, L:RB->maxstack
  |  ja ->gate_lf_growstack
  |  mov RB, LJ_TNIL
  |1:  // Clear free slots until top of frame.
  |  mov [RC], RB
  |  mov [RC+8], RB
  |  add RC, 16
  |  cmp RC, RA
  |  jb <1
  |  ins_next

--Mike