hipe_arm_frame.erl

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%%% -*- erlang-indent-level: 2 -*-
%%% $Id$

-module(hipe_arm_frame).
-export([frame/1]).

-include("hipe_arm.hrl").
-include("../rtl/hipe_literals.hrl").

-define(LIVENESS_ALL, hipe_arm_liveness_gpr). % since we have no FP yet

frame(Defun) ->
  Formals = fix_formals(hipe_arm:defun_formals(Defun)),
  Temps0 = all_temps(hipe_arm:defun_code(Defun), Formals),
  MinFrame = defun_minframe(Defun),
  Temps = ensure_minframe(MinFrame, Temps0),
  ClobbersLR = clobbers_lr(hipe_arm:defun_code(Defun)),
  CFG0 = hipe_arm_cfg:init(Defun),
  Liveness = ?LIVENESS_ALL:analyse(CFG0),
  CFG1 = do_body(CFG0, Liveness, Formals, Temps, ClobbersLR),
  hipe_arm_cfg:linearise(CFG1).

fix_formals(Formals) ->
  fix_formals(hipe_arm_registers:nr_args(), Formals).

fix_formals(0, Rest) -> Rest;
fix_formals(N, [_|Rest]) -> fix_formals(N-1, Rest);
fix_formals(_, []) -> [].

do_body(CFG0, Liveness, Formals, Temps, ClobbersLR) ->
  Context = mk_context(Liveness, Formals, Temps, ClobbersLR),
  CFG1 = do_blocks(CFG0, Context),
  do_prologue(CFG1, Context).

do_blocks(CFG, Context) ->
  Labels = hipe_arm_cfg:labels(CFG),
  do_blocks(Labels, CFG, Context).

do_blocks([Label|Labels], CFG, Context) ->
  Liveness = context_liveness(Context),
  LiveOut = ?LIVENESS_ALL:liveout(Liveness, Label),
  Block = hipe_arm_cfg:bb(CFG, Label),
  Code = hipe_bb:code(Block),
  NewCode = do_block(Code, LiveOut, Context),
  NewBlock = hipe_bb:code_update(Block, NewCode),
  NewCFG = hipe_arm_cfg:bb_add(CFG, Label, NewBlock),
  do_blocks(Labels, NewCFG, Context);
do_blocks([], CFG, _) ->
  CFG.

do_block(Insns, LiveOut, Context) ->
  do_block(Insns, LiveOut, Context, context_framesize(Context), []).

do_block([I|Insns], LiveOut, Context, FPoff0, RevCode) ->
  {NewIs, FPoff1} = do_insn(I, LiveOut, Context, FPoff0),
  do_block(Insns, LiveOut, Context, FPoff1, lists:reverse(NewIs, RevCode));
do_block([], _, Context, FPoff, RevCode) ->
  FPoff0 = context_framesize(Context),
  if FPoff =:= FPoff0 -> [];
     true -> exit({?MODULE,do_block,FPoff})
  end,
  lists:reverse(RevCode, []).

do_insn(I, LiveOut, Context, FPoff) ->
  case I of
    #pseudo_blr{} ->
      {do_pseudo_blr(I, Context, FPoff), context_framesize(Context)};
    #pseudo_call{} ->
      do_pseudo_call(I, LiveOut, Context, FPoff);
    #pseudo_call_prepare{} ->
      do_pseudo_call_prepare(I, FPoff);
    #pseudo_move{} ->
      {do_pseudo_move(I, Context, FPoff), FPoff};
    #pseudo_tailcall{} ->
      {do_pseudo_tailcall(I, Context), context_framesize(Context)};
    _ ->
      {[I], FPoff}
  end.

%%%
%%% Moves, with Dst or Src possibly a pseudo
%%%

do_pseudo_move(I, Context, FPoff) ->
  Dst = hipe_arm:pseudo_move_dst(I),
  Src = hipe_arm:pseudo_move_src(I),
  case temp_is_pseudo(Dst) of
    true ->
      Offset = pseudo_offset(Dst, FPoff, Context),
      mk_store('str', Src, Offset, mk_sp(), []);
    _ ->
      case temp_is_pseudo(Src) of
	true ->
	  Offset = pseudo_offset(Src, FPoff, Context),
	  mk_load('ldr', Dst, Offset, mk_sp(), []);
	_ ->
	  [hipe_arm:mk_move(Dst, Src)]
      end
  end.

pseudo_offset(Temp, FPoff, Context) ->
  FPoff + context_offset(Context, Temp).

%%%
%%% Return - deallocate frame and emit 'ret $N' insn.
%%%

do_pseudo_blr(I, Context, FPoff) ->
  %% XXX: perhaps use explicit pseudo_move;mtlr,
  %% avoiding the need to hard-code Temp1 here
  %% XXX: typically only one instruction between
  %% the mtlr and the blr, ouch
  restore_lr(FPoff, Context,
	     adjust_sp(FPoff + word_size() * context_arity(Context),
		       [I])).

restore_lr(FPoff, Context, Rest) ->
  case context_clobbers_lr(Context) of
    false -> Rest;
    true ->
      LR = hipe_arm:mk_lr(),
      mk_load('ldr', LR, FPoff - word_size(), mk_sp(),
	      Rest)
  end.

adjust_sp(N, Rest) ->
  if N =:= 0 ->
      Rest;
     true ->
      SP = mk_sp(),
      hipe_arm:mk_addi(SP, SP, N, Rest)
  end.

%%%
%%% Recursive calls.
%%%

do_pseudo_call_prepare(I, FPoff0) ->
  %% Create outgoing arguments area on the stack.
  NrStkArgs = hipe_arm:pseudo_call_prepare_nrstkargs(I),
  Offset = NrStkArgs * word_size(),
  {adjust_sp(-Offset, []), FPoff0 + Offset}.

do_pseudo_call(I, LiveOut, Context, FPoff0) ->
  #arm_sdesc{exnlab=ExnLab,arity=OrigArity} = hipe_arm:pseudo_call_sdesc(I),
  FunV = hipe_arm:pseudo_call_funv(I),
  LiveTemps = [Temp || Temp <- LiveOut, temp_is_pseudo(Temp)],
  SDesc = mk_sdesc(ExnLab, Context, LiveTemps),
  ContLab = hipe_arm:pseudo_call_contlab(I),
  Linkage = hipe_arm:pseudo_call_linkage(I),
  CallCode = [hipe_arm:mk_pseudo_call(FunV, SDesc, ContLab, Linkage)],
  StkArity = max(0, OrigArity - hipe_arm_registers:nr_args()),
  context_need_stack(Context, stack_need(FPoff0, StkArity, FunV)),
  ArgsBytes = word_size() * StkArity,
  {CallCode, FPoff0 - ArgsBytes}.

stack_need(FPoff, StkArity, FunV) ->
  case FunV of
    #arm_prim{} -> FPoff;
    #arm_mfa{m=M,f=F,a=A} ->
      case erlang:is_builtin(M, F, A) of
	true -> FPoff;
	false -> stack_need_general(FPoff, StkArity)
      end;
    _ -> stack_need_general(FPoff, StkArity)
  end.

stack_need_general(FPoff, StkArity) ->
  max(FPoff, FPoff + (?ARM_LEAF_WORDS - StkArity) * word_size()).

%%%
%%% Create stack descriptors for call sites.
%%%

mk_sdesc(ExnLab, Context, Temps) ->	% for normal calls
  Temps0 = only_tagged(Temps),
  Live = mk_live(Context, Temps0),
  Arity = context_arity(Context),
  FSize = context_framesize(Context),
  hipe_arm:mk_sdesc(ExnLab, (FSize div word_size())-1, Arity,
                    list_to_tuple(Live)).

only_tagged(Temps)->
  [X || X <- Temps, hipe_arm:temp_type(X) =:= 'tagged'].

mk_live(Context, Temps) ->
  lists:sort([temp_to_slot(Context, Temp) || Temp <- Temps]).

temp_to_slot(Context, Temp) ->
  (context_framesize(Context) + context_offset(Context, Temp))
    div word_size().

mk_minimal_sdesc(Context) ->		% for inc_stack_0 calls
  hipe_arm:mk_sdesc([], 0, context_arity(Context), {}).

%%%
%%% Tailcalls.
%%%

do_pseudo_tailcall(I, Context) -> % always at FPoff=context_framesize(Context)
  Arity = context_arity(Context),
  Args = hipe_arm:pseudo_tailcall_stkargs(I),
  FunV = hipe_arm:pseudo_tailcall_funv(I),
  Linkage = hipe_arm:pseudo_tailcall_linkage(I),
  {Insns, FPoff1} = do_tailcall_args(Args, Context),
  context_need_stack(Context, FPoff1),
  StkArity = length(Args),
  FPoff2 = FPoff1 + (Arity - StkArity) * word_size(),
  context_need_stack(Context, stack_need(FPoff2, StkArity, FunV)),
  I2 =
    case FunV of
      #arm_temp{} ->
	hipe_arm:mk_bx(FunV);
      Fun ->
	hipe_arm:mk_b_fun(Fun, Linkage)
    end,
  %% XXX: break out the LR restore, just like for pseudo_blr?
  restore_lr(context_framesize(Context), Context,
	     Insns ++ adjust_sp(FPoff2, [I2])).

do_tailcall_args(Args, Context) ->
  FPoff0 = context_framesize(Context),
  Arity = context_arity(Context),
  FrameTop = word_size()*Arity,
  DangerOff = FrameTop - word_size()*length(Args),
  %%
  Moves = mk_moves(Args, FrameTop, []),
  %%
  {Stores, Simple, Conflict} =
    split_moves(Moves, Context, DangerOff, [], [], []),
  %% sanity check (shouldn't trigger any more)
  if DangerOff < -FPoff0 ->
      exit({?MODULE,do_tailcall_args,DangerOff,-FPoff0});
     true -> []
  end,
  FPoff1 = FPoff0,
  %%
  {Pushes, Pops, FPoff2} = split_conflict(Conflict, FPoff1, [], []),
  %%
  TempReg = hipe_arm_registers:temp1(),
  %%
  {adjust_sp(-(FPoff2 - FPoff1),
	     simple_moves(Pushes, FPoff2, TempReg,
			  store_moves(Stores, FPoff2, TempReg,
				      simple_moves(Simple, FPoff2, TempReg,
						   simple_moves(Pops, FPoff2, TempReg,
								[]))))),
   FPoff2}.

mk_moves([Arg|Args], Off, Moves) ->
  Off1 = Off - word_size(),
  mk_moves(Args, Off1, [{Arg,Off1}|Moves]);
mk_moves([], _, Moves) ->
  Moves.

split_moves([Move|Moves], Context, DangerOff, Stores, Simple, Conflict) ->
  {Src,DstOff} = Move,
  case src_is_pseudo(Src) of
    false ->
      split_moves(Moves, Context, DangerOff, [Move|Stores],
		  Simple, Conflict);
    true ->
      SrcOff = context_offset(Context, Src),
      Type = typeof_temp(Src),
      if SrcOff =:= DstOff ->
	  split_moves(Moves, Context, DangerOff, Stores,
		      Simple, Conflict);
	 SrcOff >= DangerOff ->
	  split_moves(Moves, Context, DangerOff, Stores,
		      Simple, [{SrcOff,DstOff,Type}|Conflict]);
	 true ->
	  split_moves(Moves, Context, DangerOff, Stores,
		      [{SrcOff,DstOff,Type}|Simple], Conflict)
      end
  end;
split_moves([], _, _, Stores, Simple, Conflict) ->
  {Stores, Simple, Conflict}.

split_conflict([{SrcOff,DstOff,Type}|Conflict], FPoff, Pushes, Pops) ->
  FPoff1 = FPoff + word_size(),
  Push = {SrcOff,-FPoff1,Type},
  Pop = {-FPoff1,DstOff,Type},
  split_conflict(Conflict, FPoff1, [Push|Pushes], [Pop|Pops]);
split_conflict([], FPoff, Pushes, Pops) ->
  {lists:reverse(Pushes), Pops, FPoff}.

simple_moves([{SrcOff,DstOff,Type}|Moves], FPoff, TempReg, Rest) ->
  Temp = hipe_arm:mk_temp(TempReg, Type),
  SP = mk_sp(),
  LoadOff = FPoff+SrcOff,
  StoreOff = FPoff+DstOff,
  simple_moves(Moves, FPoff, TempReg,
	       mk_load('ldr', Temp, LoadOff, SP,
		       mk_store('str', Temp, StoreOff, SP,
				Rest)));
simple_moves([], _, _, Rest) ->
  Rest.

store_moves([{Src,DstOff}|Moves], FPoff, TempReg, Rest) ->
  %%Type = typeof_temp(Src),
  SP = mk_sp(),
  StoreOff = FPoff+DstOff,
  {NewSrc,FixSrc} =
    case hipe_arm:is_temp(Src) of
      true ->
	{Src, []};
      _ ->
	Temp = hipe_arm:mk_temp(TempReg, 'untagged'),
	{Temp, hipe_arm:mk_li(Temp, Src)}
    end,
  store_moves(Moves, FPoff, TempReg,
	      FixSrc ++ mk_store('str', NewSrc, StoreOff, SP, Rest));
store_moves([], _, _, Rest) ->
  Rest.