%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1999-2010. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%% Purpose : Code generator for Beam.
%% The following assumptions have been made:
%%
%% 1. Matches, i.e. things with {match,M,Ret} wrappers, only return
%% values; no variables are exported. If the match would have returned
%% extra variables then these have been transformed to multiple return
%% values.
%%
%% 2. All BIF's called in guards are gc-safe so there is no need to
%% put thing on the stack in the guard. While this would in principle
%% work it would be difficult to keep track of the stack depth when
%% trimming.
%%
%% The code generation uses variable lifetime information added by
%% the v3_life module to save variables, allocate registers and
%% move registers to the stack when necessary.
%%
%% We try to use a consistent variable name scheme throughout. The
%% StackReg record is always called Bef,Int<n>,Aft.
-module(v3_codegen).
%% The main interface.
-export([module/2]).
-import(lists, [member/2,keymember/3,keysort/2,keydelete/3,
append/1,map/2,flatmap/2,filter/2,foldl/3,foldr/3,mapfoldl/3,
sort/1,reverse/1,reverse/2]).
-import(v3_life, [vdb_find/2]).
%%-compile([export_all]).
-include("v3_life.hrl").
%% Main codegen structure.
-record(cg, {lcount=1, %Label counter
finfo, %Function info label
bfail, %Fail label for BIFs
break, %Break label
recv, %Receive label
is_top_block, %Boolean: top block or not
functable=gb_trees:empty(), %Gb tree of local functions:
% {{Name,Arity},Label}
in_catch=false, %Inside a catch or not.
need_frame, %Need a stack frame.
ultimate_failure %Label for ultimate match failure.
}).
%% Stack/register state record.
-record(sr, {reg=[], %Register table
stk=[], %Stack table
res=[]}). %Reserved regs: [{reserved,I,V}]
module({Mod,Exp,Attr,Forms}, Options) ->
put(?MODULE, Options),
{Fs,St} = functions(Forms, {atom,Mod}),
erase(?MODULE),
{ok,{Mod,Exp,Attr,Fs,St#cg.lcount}}.
functions(Forms, AtomMod) ->
mapfoldl(fun (F, St) -> function(F, AtomMod, St) end, #cg{lcount=1}, Forms).
function({function,Name,Arity,Asm0,Vb,Vdb}, AtomMod, St0) ->
try
{Asm,EntryLabel,St} = cg_fun(Vb, Asm0, Vdb, AtomMod, {Name,Arity}, St0),
Func = {function,Name,Arity,EntryLabel,Asm},
{Func,St}
catch
Class:Error ->
Stack = erlang:get_stacktrace(),
io:fwrite("Function: ~w/~w\n", [Name,Arity]),
erlang:raise(Class, Error, Stack)
end.
%% cg_fun([Lkexpr], [HeadVar], Vdb, State) -> {[Ainstr],State}
cg_fun(Les, Hvs, Vdb, AtomMod, NameArity, St0) ->
{Fi,St1} = new_label(St0), %FuncInfo label
{Fl,St2} = local_func_label(NameArity, St1),
%%
%% The pattern matching compiler (in v3_kernel) no longer
%% provides its own catch-all clause, because the
%% call to erlang:exit/1 caused problem when cases were
%% used in guards. Therefore, there may be tests that
%% cannot fail (providing that there is not a bug in a
%% previous optimzation pass), but still need to provide
%% a label (there are instructions, such as is_tuple/2,
%% that do not allow {f,0}).
%%
%% We will generate an ultimate failure label and put it
%% at the end of function, followed by an 'if_end' instruction.
%% Note that and 'if_end' instruction does not need any
%% live x registers, so it will always be safe to jump to
%% it. (We never ever expect the jump to be taken, and in
%% must functions there will never be any references to
%% the label in the first place.)
%%
{UltimateMatchFail,St3} = new_label(St2),
%% Create initial stack/register state, clear unused arguments.
Bef = clear_dead(#sr{reg=foldl(fun ({var,V}, Reg) ->
put_reg(V, Reg)
end, [], Hvs),
stk=[]}, 0, Vdb),
{B,_Aft,St} = cg_list(Les, 0, Vdb, Bef,
St3#cg{bfail=0,
finfo=Fi,
ultimate_failure=UltimateMatchFail,
is_top_block=true}),
{Name,Arity} = NameArity,
Asm = [{label,Fi},{func_info,AtomMod,{atom,Name},Arity},
{label,Fl}|B++[{label,UltimateMatchFail},if_end]],
{Asm,Fl,St}.
%% cg(Lkexpr, Vdb, StackReg, State) -> {[Ainstr],StackReg,State}.
%% Generate code for a kexpr.
%% Split function into two steps for clarity, not efficiency.
cg(Le, Vdb, Bef, St) ->
cg(Le#l.ke, Le, Vdb, Bef, St).
cg({block,Es}, Le, Vdb, Bef, St) ->
block_cg(Es, Le, Vdb, Bef, St);
cg({match,M,Rs}, Le, Vdb, Bef, St) ->
match_cg(M, Rs, Le, Vdb, Bef, St);
cg({guard_match,M,Rs}, Le, Vdb, Bef, St) ->
guard_match_cg(M, Rs, Le, Vdb, Bef, St);
cg({match_fail,F}, Le, Vdb, Bef, St) ->
match_fail_cg(F, Le, Vdb, Bef, St);
cg({call,Func,As,Rs}, Le, Vdb, Bef, St) ->
call_cg(Func, As, Rs, Le, Vdb, Bef, St);
cg({enter,Func,As}, Le, Vdb, Bef, St) ->
enter_cg(Func, As, Le, Vdb, Bef, St);
cg({bif,Bif,As,Rs}, Le, Vdb, Bef, St) ->
bif_cg(Bif, As, Rs, Le, Vdb, Bef, St);
cg({gc_bif,Bif,As,Rs}, Le, Vdb, Bef, St) ->
gc_bif_cg(Bif, As, Rs, Le, Vdb, Bef, St);
cg({receive_loop,Te,Rvar,Rm,Tes,Rs}, Le, Vdb, Bef, St) ->
recv_loop_cg(Te, Rvar, Rm, Tes, Rs, Le, Vdb, Bef, St);
cg(receive_next, Le, Vdb, Bef, St) ->
recv_next_cg(Le, Vdb, Bef, St);
cg(receive_accept, _Le, _Vdb, Bef, St) -> {[remove_message],Bef,St};
cg({'try',Ta,Vs,Tb,Evs,Th,Rs}, Le, Vdb, Bef, St) ->
try_cg(Ta, Vs, Tb, Evs, Th, Rs, Le, Vdb, Bef, St);
cg({try_enter,Ta,Vs,Tb,Evs,Th}, Le, Vdb, Bef, St) ->
try_enter_cg(Ta, Vs, Tb, Evs, Th, Le, Vdb, Bef, St);
cg({'catch',Cb,R}, Le, Vdb, Bef, St) ->
catch_cg(Cb, R, Le, Vdb, Bef, St);
cg({set,Var,Con}, Le, Vdb, Bef, St) ->
set_cg(Var, Con, Le, Vdb, Bef, St);
cg({return,Rs}, Le, Vdb, Bef, St) -> return_cg(Rs, Le, Vdb, Bef, St);
cg({break,Bs}, Le, Vdb, Bef, St) -> break_cg(Bs, Le, Vdb, Bef, St);
cg({guard_break,Bs,N}, Le, Vdb, Bef, St) ->
guard_break_cg(Bs, N, Le, Vdb, Bef, St);
cg({need_heap,H}, _Le, _Vdb, Bef, St) ->
{[{test_heap,H,max_reg(Bef#sr.reg)}],Bef,St}.
%% cg_list([Kexpr], FirstI, Vdb, StackReg, St) -> {[Ainstr],StackReg,St}.
cg_list(Kes, I, Vdb, Bef, St0) ->
{Keis,{Aft,St1}} =
flatmapfoldl(fun (Ke, {Inta,Sta}) ->
{Keis,Intb,Stb} = cg(Ke, Vdb, Inta, Sta),
{Keis,{Intb,Stb}}
end, {Bef,St0}, need_heap(Kes, I)),
{Keis,Aft,St1}.
%% need_heap([Lkexpr], I, St) -> [Lkexpr].
%% Insert need_heap instructions in Kexpr list. Try to be smart and
%% collect them together as much as possible.
need_heap(Kes0, I) ->
{Kes,H} = need_heap_0(reverse(Kes0), 0, []),
%% Prepend need_heap if necessary.
need_heap_need(I, H) ++ Kes.
need_heap_0([Ke|Kes], H0, Acc) ->
{Ns,H} = need_heap_1(Ke, H0),
need_heap_0(Kes, H, [Ke|Ns]++Acc);
need_heap_0([], H, Acc) ->
{Acc,H}.
need_heap_1(#l{ke={set,_,{binary,_}},i=I}, H) ->
{need_heap_need(I, H),0};
need_heap_1(#l{ke={set,_,Val}}, H) ->
%% Just pass through adding to needed heap.
{[],H + case Val of
{cons,_} -> 2;
{tuple,Es} -> 1 + length(Es);
_Other -> 0
end};
need_heap_1(#l{ke={bif,dsetelement,_As,_Rs},i=I}, H) ->
{need_heap_need(I, H),0};
need_heap_1(#l{ke={bif,{make_fun,_,_,_,_},_As,_Rs},i=I}, H) ->
{need_heap_need(I, H),0};
need_heap_1(#l{ke={bif,bs_init_writable,_As,_Rs},i=I}, H) ->
{need_heap_need(I, H),0};
need_heap_1(#l{ke={bif,_Bif,_As,_Rs}}, H) ->
{[],H};
need_heap_1(#l{i=I}, H) ->
{need_heap_need(I, H),0}.
need_heap_need(_I, 0) -> [];
need_heap_need(I, H) -> [#l{ke={need_heap,H},i=I}].
%% match_cg(Match, [Ret], Le, Vdb, StackReg, State) ->
%% {[Ainstr],StackReg,State}.
%% Generate code for a match. First save all variables on the stack
%% that are to survive after the match. We leave saved variables in
%% their registers as they might actually be in the right place.
match_cg(M, Rs, Le, Vdb, Bef, St0) ->
I = Le#l.i,
{Sis,Int0} = adjust_stack(Bef, I, I+1, Vdb),
{B,St1} = new_label(St0),
{Mis,Int1,St2} = match_cg(M, St0#cg.ultimate_failure,
Int0, St1#cg{break=B}),
%% Put return values in registers.
Reg = load_vars(Rs, Int1#sr.reg),
{Sis ++ Mis ++ [{label,B}],
clear_dead(Int1#sr{reg=Reg}, I, Vdb),
St2#cg{break=St1#cg.break}}.
guard_match_cg(M, Rs, Le, Vdb, Bef, St0) ->
I = Le#l.i,
{B,St1} = new_label(St0),
#cg{bfail=Fail} = St1,
{Mis,Aft,St2} = match_cg(M, Fail, Bef, St1#cg{break=B}),
%% Update the register descriptors for the return registers.
Reg = guard_match_regs(Aft#sr.reg, Rs),
{Mis ++ [{label,B}],
clear_dead(Aft#sr{reg=Reg}, I, Vdb),
St2#cg{break=St1#cg.break}}.
guard_match_regs([{I,gbreakvar}|Rs], [{var,V}|Vs]) ->
[{I,V}|guard_match_regs(Rs, Vs)];
guard_match_regs([R|Rs], Vs) ->
[R|guard_match_regs(Rs, Vs)];
guard_match_regs([], []) -> [].
%% match_cg(Match, Fail, StackReg, State) -> {[Ainstr],StackReg,State}.
%% Generate code for a match tree. N.B. there is no need pass Vdb
%% down as each level which uses this takes its own internal Vdb not
%% the outer one.
match_cg(Le, Fail, Bef, St) ->
match_cg(Le#l.ke, Le, Fail, Bef, St).
match_cg({alt,F,S}, _Le, Fail, Bef, St0) ->
{Tf,St1} = new_label(St0),
{Fis,Faft,St2} = match_cg(F, Tf, Bef, St1),
{Sis,Saft,St3} = match_cg(S, Fail, Bef, St2),
Aft = sr_merge(Faft, Saft),
{Fis ++ [{label,Tf}] ++ Sis,Aft,St3};
match_cg({select,{var,Vname}=V,Scs0}, #l{a=Anno}, Fail, Bef, St) ->
ReuseForContext = member(reuse_for_context, Anno) andalso
find_reg(Vname, Bef#sr.reg) =/= error,
Scs = case ReuseForContext of
false -> Scs0;
true -> bsm_rename_ctx(Scs0, Vname)
end,
match_fmf(fun (S, F, Sta) ->
select_cg(S, V, F, Fail, Bef, Sta) end,
Fail, St, Scs);
match_cg({guard,Gcs}, _Le, Fail, Bef, St) ->
match_fmf(fun (G, F, Sta) -> guard_clause_cg(G, F, Bef, Sta) end,
Fail, St, Gcs);
match_cg({block,Es}, Le, _Fail, Bef, St) ->
%% Must clear registers and stack of dead variables.
Int = clear_dead(Bef, Le#l.i, Le#l.vdb),
block_cg(Es, Le, Int, St).
%% match_fail_cg(FailReason, Le, Vdb, StackReg, State) ->
%% {[Ainstr],StackReg,State}.
%% Generate code for the match_fail "call". N.B. there is no generic
%% case for when the fail value has been created elsewhere.
match_fail_cg({function_clause,As}, Le, Vdb, Bef, St) ->
%% Must have the args in {x,0}, {x,1},...
{Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
{Sis ++ [{jump,{f,St#cg.finfo}}],
Int#sr{reg=clear_regs(Int#sr.reg)},St};
match_fail_cg({badmatch,Term}, Le, Vdb, Bef, St) ->
R = cg_reg_arg(Term, Bef),
Int0 = clear_dead(Bef, Le#l.i, Vdb),
{Sis,Int} = adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb),
{Sis ++ [{badmatch,R}],
Int#sr{reg=clear_regs(Int0#sr.reg)},St};
match_fail_cg({case_clause,Reason}, Le, Vdb, Bef, St) ->
R = cg_reg_arg(Reason, Bef),
Int0 = clear_dead(Bef, Le#l.i, Vdb),
{Sis,Int} = adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb),
{Sis++[{case_end,R}],
Int#sr{reg=clear_regs(Bef#sr.reg)},St};
match_fail_cg(if_clause, Le, Vdb, Bef, St) ->
Int0 = clear_dead(Bef, Le#l.i, Vdb),
{Sis,Int1} = adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb),
{Sis++[if_end],Int1#sr{reg=clear_regs(Int1#sr.reg)},St};
match_fail_cg({try_clause,Reason}, Le, Vdb, Bef, St) ->
R = cg_reg_arg(Reason, Bef),
Int0 = clear_dead(Bef, Le#l.i, Vdb),
{Sis,Int} = adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb),
{Sis ++ [{try_case_end,R}],
Int#sr{reg=clear_regs(Int0#sr.reg)},St}.
%% bsm_rename_ctx([Clause], Var) -> [Clause]
%% We know from an annotation that the register for a binary can
%% be reused for the match context because the two are not truly
%% alive at the same time (even though the conservative life time
%% information calculated by v3_life says so).
%%
%% The easiest way to have those variables share the same register is
%% to rename the variable with the shortest life-span (the match
%% context) to the variable for the binary (which can have a very
%% long life-time because it is locked during matching). We KNOW that
%% the match state variable will only be alive during the matching.
%%
%% We must also remove all information about the match context
%% variable from all life-time information databases (Vdb).
bsm_rename_ctx([#l{ke={type_clause,binary,
[#l{ke={val_clause,{binary,{var,Old}},Ke0}}=L2]}}=L1|Cs], New) ->
Ke = bsm_rename_ctx(Ke0, Old, New, false),
[L1#l{ke={type_clause,binary,
[L2#l{ke={val_clause,{binary,{var,New}},Ke}}]}}|bsm_rename_ctx(Cs, New)];
bsm_rename_ctx([C|Cs], New) ->
[C|bsm_rename_ctx(Cs, New)];
bsm_rename_ctx([], _) -> [].
%% bsm_rename_ctx(Ke, OldName, NewName, InProt) -> Ke'
%% Rename and clear OldName from life-time information. We must
%% recurse into any block contained in a protected, but it would
%% only complicatate things to recurse into blocks not in a protected
%% (the match context variable is not live inside them).
bsm_rename_ctx(#l{ke={select,{var,V},Cs0}}=L, Old, New, InProt) ->
Cs = bsm_rename_ctx_list(Cs0, Old, New, InProt),
L#l{ke={select,{var,bsm_rename_var(V, Old, New)},Cs}};
bsm_rename_ctx(#l{ke={type_clause,Type,Cs0}}=L, Old, New, InProt) ->
Cs = bsm_rename_ctx_list(Cs0, Old, New, InProt),
L#l{ke={type_clause,Type,Cs}};
bsm_rename_ctx(#l{ke={val_clause,{bin_end,V},Ke0}}=L, Old, New, InProt) ->
Ke = bsm_rename_ctx(Ke0, Old, New, InProt),
L#l{ke={val_clause,{bin_end,bsm_rename_var(V, Old, New)},Ke}};
bsm_rename_ctx(#l{ke={val_clause,{bin_seg,V,Sz,U,Type,Fl,Vs},Ke0}}=L,
Old, New, InProt) ->
Ke = bsm_rename_ctx(Ke0, Old, New, InProt),
L#l{ke={val_clause,{bin_seg,bsm_rename_var(V, Old, New),Sz,U,Type,Fl,Vs},Ke}};
bsm_rename_ctx(#l{ke={val_clause,{bin_int,V,Sz,U,Fl,Val,Vs},Ke0}}=L,
Old, New, InProt) ->
Ke = bsm_rename_ctx(Ke0, Old, New, InProt),
L#l{ke={val_clause,{bin_int,bsm_rename_var(V, Old, New),Sz,U,Fl,Val,Vs},Ke}};
bsm_rename_ctx(#l{ke={val_clause,Val,Ke0}}=L, Old, New, InProt) ->
Ke = bsm_rename_ctx(Ke0, Old, New, InProt),
L#l{ke={val_clause,Val,Ke}};
bsm_rename_ctx(#l{ke={alt,F0,S0}}=L, Old, New, InProt) ->
F = bsm_rename_ctx(F0, Old, New, InProt),
S = bsm_rename_ctx(S0, Old, New, InProt),
L#l{ke={alt,F,S}};
bsm_rename_ctx(#l{ke={guard,Gcs0}}=L, Old, New, InProt) ->
Gcs = bsm_rename_ctx_list(Gcs0, Old, New, InProt),
L#l{ke={guard,Gcs}};
bsm_rename_ctx(#l{ke={guard_clause,G0,B0}}=L, Old, New, InProt) ->
G = bsm_rename_ctx(G0, Old, New, InProt),
B = bsm_rename_ctx(B0, Old, New, InProt),
%% A guard clause may cause unsaved variables to be saved on the stack.
%% Since the match state variable Old is an alias for New (uses the
%% same register), it is neither in the stack nor register descriptor
%% lists and we would crash when we didn't find it unless we remove
%% it from the database.
bsm_forget_var(L#l{ke={guard_clause,G,B}}, Old);
bsm_rename_ctx(#l{ke={protected,Ts0,Rs}}=L, Old, New, _InProt) ->
InProt = true,
Ts = bsm_rename_ctx_list(Ts0, Old, New, InProt),
bsm_forget_var(L#l{ke={protected,Ts,Rs}}, Old);
bsm_rename_ctx(#l{ke={match,Ms0,Rs}}=L, Old, New, InProt) ->
Ms = bsm_rename_ctx(Ms0, Old, New, InProt),
L#l{ke={match,Ms,Rs}};
bsm_rename_ctx(#l{ke={guard_match,Ms0,Rs}}=L, Old, New, InProt) ->
Ms = bsm_rename_ctx(Ms0, Old, New, InProt),
L#l{ke={guard_match,Ms,Rs}};
bsm_rename_ctx(#l{ke={test,_,_}}=L, _, _, _) -> L;
bsm_rename_ctx(#l{ke={bif,_,_,_}}=L, _, _, _) -> L;
bsm_rename_ctx(#l{ke={gc_bif,_,_,_}}=L, _, _, _) -> L;
bsm_rename_ctx(#l{ke={set,_,_}}=L, _, _, _) -> L;
bsm_rename_ctx(#l{ke={block,_}}=L, Old, _, false) ->
%% This block is not inside a protected. The match context variable cannot
%% possibly be live inside the block.
bsm_forget_var(L, Old);
bsm_rename_ctx(#l{ke={block,Bl0}}=L, Old, New, true) ->
%% A block in a protected. We must recursively rename the variable
%% inside the block.
Bl = bsm_rename_ctx_list(Bl0, Old, New, true),
bsm_forget_var(L#l{ke={block,Bl}}, Old);
bsm_rename_ctx(#l{ke={guard_break,Bs,Locked0}}=L0, Old, _New, _InProt) ->
Locked = Locked0 -- [Old],
L = L0#l{ke={guard_break,Bs,Locked}},
bsm_forget_var(L, Old).
bsm_rename_ctx_list([C|Cs], Old, New, InProt) ->
[bsm_rename_ctx(C, Old, New, InProt)|
bsm_rename_ctx_list(Cs, Old, New, InProt)];
bsm_rename_ctx_list([], _, _, _) -> [].
bsm_rename_var(Old, Old, New) -> New;
bsm_rename_var(V, _, _) -> V.
%% bsm_forget_var(#l{}, Variable) -> #l{}
%% Remove a variable from the variable life-time database.
bsm_forget_var(#l{vdb=Vdb}=L, V) ->
L#l{vdb=keydelete(V, 1, Vdb)}.
%% block_cg([Kexpr], Le, Vdb, StackReg, St) -> {[Ainstr],StackReg,St}.
%% block_cg([Kexpr], Le, StackReg, St) -> {[Ainstr],StackReg,St}.
block_cg(Es, Le, _Vdb, Bef, St) ->
block_cg(Es, Le, Bef, St).
block_cg(Es, Le, Bef, #cg{is_top_block=false}=St) ->
cg_block(Es, Le#l.i, Le#l.vdb, Bef, St);
block_cg(Es, Le, Bef, St0) ->
{Is0,Aft,St} = cg_block(Es, Le#l.i, Le#l.vdb, Bef,
St0#cg{is_top_block=false,need_frame=false}),
Is = top_level_block(Is0, Aft, max_reg(Bef#sr.reg), St),
{Is,Aft,St#cg{is_top_block=true}}.
cg_block([], _I, _Vdb, Bef, St0) ->
{[],Bef,St0};
cg_block(Kes0, I, Vdb, Bef, St0) ->
{Kes2,Int1,St1} =
case basic_block(Kes0) of
{Kes1,LastI,Args,Rest} ->
Ke = hd(Kes1),
Fb = Ke#l.i,
cg_basic_block(Kes1, Fb, LastI, Args, Vdb, Bef, St0);
{Kes1,Rest} ->
cg_list(Kes1, I, Vdb, Bef, St0)
end,
{Kes3,Int2,St2} = cg_block(Rest, I, Vdb, Int1, St1),
{Kes2 ++ Kes3,Int2,St2}.
basic_block(Kes) -> basic_block(Kes, []).
basic_block([Le|Les], Acc) ->
case collect_block(Le#l.ke) of
include -> basic_block(Les, [Le|Acc]);
{block_end,As} ->
case Acc of
[] ->
%% If the basic block does not contain any set instructions,
%% it serves no useful purpose to do basic block optimizations.
{[Le],Les};
_ ->
{reverse(Acc, [Le]),Le#l.i,As,Les}
end;
no_block -> {reverse(Acc, [Le]),Les}
end.
collect_block({set,_,{binary,_}}) -> no_block;
collect_block({set,_,_}) -> include;
collect_block({call,{var,_}=Var,As,_Rs}) -> {block_end,As++[Var]};
collect_block({call,Func,As,_Rs}) -> {block_end,As++func_vars(Func)};
collect_block({enter,{var,_}=Var,As})-> {block_end,As++[Var]};
collect_block({enter,Func,As}) -> {block_end,As++func_vars(Func)};
collect_block({return,Rs}) -> {block_end,Rs};
collect_block({break,Bs}) -> {block_end,Bs};
collect_block(_) -> no_block.
func_vars({remote,M,F}) when element(1, M) =:= var;
element(1, F) =:= var ->
[M,F];
func_vars(_) -> [].
%% cg_basic_block([Kexpr], FirstI, LastI, As, Vdb, StackReg, State) ->
%% {[Ainstr],StackReg,State}.
cg_basic_block(Kes, Fb, Lf, As, Vdb, Bef, St0) ->
Res = make_reservation(As, 0),
Regs0 = reserve(Res, Bef#sr.reg, Bef#sr.stk),
Stk = extend_stack(Bef, Lf, Lf+1, Vdb),
Int0 = Bef#sr{reg=Regs0,stk=Stk,res=Res},
X0_v0 = x0_vars(As, Fb, Lf, Vdb),
{Keis,{Aft,_,St1}} =
flatmapfoldl(fun(Ke, St) -> cg_basic_block(Ke, St, Lf, Vdb) end,
{Int0,X0_v0,St0}, need_heap(Kes, Fb)),
{Keis,Aft,St1}.
cg_basic_block(#l{ke={need_heap,_}}=Ke, {Inta,X0v,Sta}, _Lf, Vdb) ->
{Keis,Intb,Stb} = cg(Ke, Vdb, Inta, Sta),
{Keis, {Intb,X0v,Stb}};
cg_basic_block(Ke, {Inta,X0_v1,Sta}, Lf, Vdb) ->
{Sis,Intb} = save_carefully(Inta, Ke#l.i, Lf+1, Vdb),
{X0_v2,Intc} = allocate_x0(X0_v1, Ke#l.i, Intb),
Intd = reserve(Intc),
{Keis,Inte,Stb} = cg(Ke, Vdb, Intd, Sta),
{Sis ++ Keis, {Inte,X0_v2,Stb}}.
make_reservation([], _) -> [];
make_reservation([{var,V}|As], I) -> [{I,V}|make_reservation(As, I+1)];
make_reservation([A|As], I) -> [{I,A}|make_reservation(As, I+1)].
reserve(Sr) -> Sr#sr{reg=reserve(Sr#sr.res, Sr#sr.reg, Sr#sr.stk)}.
reserve([{I,V}|Rs], [free|Regs], Stk) -> [{reserved,I,V}|reserve(Rs, Regs, Stk)];
reserve([{I,V}|Rs], [{I,V}|Regs], Stk) -> [{I,V}|reserve(Rs, Regs, Stk)];
reserve([{I,V}|Rs], [{I,Var}|Regs], Stk) ->
case on_stack(Var, Stk) of
true -> [{reserved,I,V}|reserve(Rs, Regs, Stk)];
false -> [{I,Var}|reserve(Rs, Regs, Stk)]
end;
reserve([{I,V}|Rs], [{reserved,I,_}|Regs], Stk) ->
[{reserved,I,V}|reserve(Rs, Regs, Stk)];
%reserve([{I,V}|Rs], [Other|Regs], Stk) -> [Other|reserve(Rs, Regs, Stk)];
reserve([{I,V}|Rs], [], Stk) -> [{reserved,I,V}|reserve(Rs, [], Stk)];
reserve([], Regs, _) -> Regs.
extend_stack(Bef, Fb, Lf, Vdb) ->
Stk0 = clear_dead_stk(Bef#sr.stk, Fb, Vdb),
Saves = [V || {V,F,L} <- Vdb,
F < Fb,
L >= Lf,
not on_stack(V, Stk0)],
Stk1 = foldl(fun (V, Stk) -> put_stack(V, Stk) end, Stk0, Saves),
Bef#sr.stk ++ lists:duplicate(length(Stk1) - length(Bef#sr.stk), free).
save_carefully(Bef, Fb, Lf, Vdb) ->
Stk = Bef#sr.stk,
%% New variables that are in use but not on stack.
New = [VFL || {V,F,L} = VFL <- Vdb,
F < Fb,
L >= Lf,
not on_stack(V, Stk)],
Saves = [V || {V,_,_} <- keysort(2, New)],
save_carefully(Saves, Bef, []).
save_carefully([], Bef, Acc) -> {reverse(Acc),Bef};
save_carefully([V|Vs], Bef, Acc) ->
case put_stack_carefully(V, Bef#sr.stk) of
error -> {reverse(Acc),Bef};
Stk1 ->
SrcReg = fetch_reg(V, Bef#sr.reg),
Move = {move,SrcReg,fetch_stack(V, Stk1)},
{x,_} = SrcReg, %Assertion - must be X register.
save_carefully(Vs, Bef#sr{stk=Stk1}, [Move|Acc])
end.
x0_vars([], _Fb, _Lf, _Vdb) -> [];
x0_vars([{var,V}|_], Fb, _Lf, Vdb) ->
{V,F,_L} = VFL = vdb_find(V, Vdb),
x0_vars1([VFL], Fb, F, Vdb);
x0_vars([X0|_], Fb, Lf, Vdb) ->
x0_vars1([{X0,Lf,Lf}], Fb, Lf, Vdb).
x0_vars1(X0, Fb, Xf, Vdb) ->
Vs0 = [VFL || {_V,F,L}=VFL <- Vdb,
F >= Fb,
L < Xf],
Vs1 = keysort(3, Vs0),
keysort(2, X0++Vs1).
allocate_x0([], _, Bef) -> {[],Bef#sr{res=[]}};
allocate_x0([{_,_,L}|Vs], I, Bef) when L =< I ->
allocate_x0(Vs, I, Bef);
allocate_x0([{V,_F,_L}=VFL|Vs], _, Bef) ->
{[VFL|Vs],Bef#sr{res=reserve_x0(V, Bef#sr.res)}}.
reserve_x0(V, [_|Res]) -> [{0,V}|Res];
reserve_x0(V, []) -> [{0,V}].
top_level_block(Keis, #sr{stk=[]}, _MaxRegs, #cg{need_frame=false}) ->
Keis;
top_level_block(Keis, Bef, MaxRegs, _St) ->
%% This top block needs an allocate instruction before it, and a
%% deallocate instruction before each return.
FrameSz = length(Bef#sr.stk),
MaxY = FrameSz-1,
Keis1 = flatmap(fun ({call_only,Arity,Func}) ->
[{call_last,Arity,Func,FrameSz}];
({call_ext_only,Arity,Func}) ->
[{call_ext_last,Arity,Func,FrameSz}];
({apply_only,Arity}) ->
[{apply_last,Arity,FrameSz}];
(return) ->
[{deallocate,FrameSz},return];
(Tuple) when is_tuple(Tuple) ->
[turn_yregs(tuple_size(Tuple), Tuple, MaxY)];
(Other) ->
[Other]
end, Keis),
[{allocate_zero,FrameSz,MaxRegs}|Keis1].
%% turn_yregs(Size, Tuple, MaxY) -> Tuple'
%% Renumber y register so that {y,0} becomes {y,FrameSize-1},
%% {y,FrameSize-1} becomes {y,0} and so on. This is to make nested
%% catches work. The code generation algorithm gives a lower register
%% number to the outer catch, which is wrong.
turn_yregs(0, Tp, _) -> Tp;
turn_yregs(El, Tp, MaxY) when element(1, element(El, Tp)) =:= yy ->
turn_yregs(El-1, setelement(El, Tp, {y,MaxY-element(2, element(El, Tp))}), MaxY);
turn_yregs(El, Tp, MaxY) when is_list(element(El, Tp)) ->
New = map(fun ({yy,YY}) -> {y,MaxY-YY};
(Other) -> Other end, element(El, Tp)),
turn_yregs(El-1, setelement(El, Tp, New), MaxY);
turn_yregs(El, Tp, MaxY) ->
turn_yregs(El-1, Tp, MaxY).
%% select_cg(Sclause, V, TypeFail, ValueFail, StackReg, State) ->
%% {Is,StackReg,State}.
%% Selecting type and value needs two failure labels, TypeFail is the
%% label to jump to of the next type test when this type fails, and
%% ValueFail is the label when this type is correct but the value is
%% wrong. These are different as in the second case there is no need
%% to try the next type, it will always fail.
select_cg(#l{ke={type_clause,cons,[S]}}, {var,V}, Tf, Vf, Bef, St) ->
select_cons(S, V, Tf, Vf, Bef, St);
select_cg(#l{ke={type_clause,nil,[S]}}, {var,V}, Tf, Vf, Bef, St) ->
select_nil(S, V, Tf, Vf, Bef, St);
select_cg(#l{ke={type_clause,binary,[S]}}, {var,V}, Tf, Vf, Bef, St) ->
select_binary(S, V, Tf, Vf, Bef, St);
select_cg(#l{ke={type_clause,bin_seg,S}}, {var,V}, Tf, _Vf, Bef, St) ->
select_bin_segs(S, V, Tf, Bef, St);
select_cg(#l{ke={type_clause,bin_int,S}}, {var,V}, Tf, _Vf, Bef, St) ->
select_bin_segs(S, V, Tf, Bef, St);
select_cg(#l{ke={type_clause,bin_end,[S]}}, {var,V}, Tf, _Vf, Bef, St) ->
select_bin_end(S, V, Tf, Bef, St);
select_cg(#l{ke={type_clause,Type,Scs}}, {var,V}, Tf, Vf, Bef, St0) ->
{Vis,{Aft,St1}} =
mapfoldl(fun (S, {Int,Sta}) ->
{Val,Is,Inta,Stb} = select_val(S, V, Vf, Bef, Sta),
{{Is,[Val]},{sr_merge(Int, Inta),Stb}}
end, {void,St0}, Scs),
OptVls = combine(lists:sort(combine(Vis))),
{Vls,Sis,St2} = select_labels(OptVls, St1, [], []),
{select_val_cg(Type, fetch_var(V, Bef), Vls, Tf, Vf, Sis), Aft, St2}.
select_val_cg(tuple, R, [Arity,{f,Lbl}], Tf, Vf, [{label,Lbl}|Sis]) ->
[{test,is_tuple,{f,Tf},[R]},{test,test_arity,{f,Vf},[R,Arity]}|Sis];
select_val_cg(tuple, R, Vls, Tf, Vf, Sis) ->
[{test,is_tuple,{f,Tf},[R]},{select_tuple_arity,R,{f,Vf},{list,Vls}}|Sis];
select_val_cg(Type, R, [Val, {f,Lbl}], Fail, Fail, [{label,Lbl}|Sis]) ->
[{test,is_eq_exact,{f,Fail},[R,{Type,Val}]}|Sis];
select_val_cg(Type, R, [Val, {f,Lbl}], Tf, Vf, [{label,Lbl}|Sis]) ->
[{test,select_type_test(Type),{f,Tf},[R]},
{test,is_eq_exact,{f,Vf},[R,{Type,Val}]}|Sis];
select_val_cg(Type, R, Vls0, Tf, Vf, Sis) ->
Vls1 = map(fun ({f,_Lbl} = F) -> F;
(Value) -> {Type,Value}
end, Vls0),
[{test,select_type_test(Type),{f,Tf},[R]}, {select_val,R,{f,Vf},{list,Vls1}}|Sis].
select_type_test(integer) -> is_integer;
select_type_test(atom) -> is_atom;
select_type_test(float) -> is_float.
combine([{Is,Vs1}, {Is,Vs2}|Vis]) -> combine([{Is,Vs1 ++ Vs2}|Vis]);
combine([V|Vis]) -> [V|combine(Vis)];
combine([]) -> [].
select_labels([{Is,Vs}|Vis], St0, Vls, Sis) ->
{Lbl,St1} = new_label(St0),
select_labels(Vis, St1, add_vls(Vs, Lbl, Vls), [[{label,Lbl}|Is]|Sis]);
select_labels([], St, Vls, Sis) ->
{Vls,append(Sis),St}.
add_vls([V|Vs], Lbl, Acc) ->
add_vls(Vs, Lbl, [V, {f,Lbl}|Acc]);
add_vls([], _, Acc) -> Acc.
select_cons(#l{ke={val_clause,{cons,Es},B},i=I,vdb=Vdb}, V, Tf, Vf, Bef, St0) ->
{Eis,Int,St1} = select_extract_cons(V, Es, I, Vdb, Bef, St0),
{Bis,Aft,St2} = match_cg(B, Vf, Int, St1),
{[{test,is_nonempty_list,{f,Tf},[fetch_var(V, Bef)]}] ++ Eis ++ Bis,Aft,St2}.
select_nil(#l{ke={val_clause,nil,B}}, V, Tf, Vf, Bef, St0) ->
{Bis,Aft,St1} = match_cg(B, Vf, Bef, St0),
{[{test,is_nil,{f,Tf},[fetch_var(V, Bef)]}] ++ Bis,Aft,St1}.
select_binary(#l{ke={val_clause,{binary,{var,V}},B},i=I,vdb=Vdb},
V, Tf, Vf, Bef, St0) ->
Int0 = clear_dead(Bef#sr{reg=Bef#sr.reg}, I, Vdb),
{Bis,Aft,St1} = match_cg(B, Vf, Int0, St0),
CtxReg = fetch_var(V, Int0),
Live = max_reg(Bef#sr.reg),
{[{test,bs_start_match2,{f,Tf},Live,[CtxReg,V],CtxReg},
{bs_save2,CtxReg,{V,V}}|Bis],
Aft,St1};
select_binary(#l{ke={val_clause,{binary,{var,Ivar}},B},i=I,vdb=Vdb},
V, Tf, Vf, Bef, St0) ->
Regs = put_reg(Ivar, Bef#sr.reg),
Int0 = clear_dead(Bef#sr{reg=Regs}, I, Vdb),
{Bis,Aft,St1} = match_cg(B, Vf, Int0, St0),
CtxReg = fetch_var(Ivar, Int0),
Live = max_reg(Bef#sr.reg),
{[{test,bs_start_match2,{f,Tf},Live,[fetch_var(V, Bef),Ivar],CtxReg},
{bs_save2,CtxReg,{Ivar,Ivar}}|Bis],
Aft,St1}.
%% New instructions for selection of binary segments.
select_bin_segs(Scs, Ivar, Tf, Bef, St) ->
match_fmf(fun(S, Fail, Sta) ->
select_bin_seg(S, Ivar, Fail, Bef, Sta) end,
Tf, St, Scs).
select_bin_seg(#l{ke={val_clause,{bin_seg,Ctx,Size,U,T,Fs0,Es},B},i=I,vdb=Vdb,a=A},
Ivar, Fail, Bef, St0) ->
Fs = [{anno,A}|Fs0],
{Mis,Int,St1} = select_extract_bin(Es, Size, U, T, Fs, Fail,
I, Vdb, Bef, Ctx, B, St0),
{Bis,Aft,St2} = match_cg(B, Fail, Int, St1),
CtxReg = fetch_var(Ctx, Bef),
Is = if
Mis =:= [] ->
%% No bs_restore2 instruction needed if no match instructions.
Bis;
true ->
[{bs_restore2,CtxReg,{Ctx,Ivar}}|Mis++Bis]
end,
{Is,Aft,St2};
select_bin_seg(#l{ke={val_clause,{bin_int,Ctx,Sz,U,Fs,Val,Es},B},i=I,vdb=Vdb},
Ivar, Fail, Bef, St0) ->
{Mis,Int,St1} = select_extract_int(Es, Val, Sz, U, Fs, Fail,
I, Vdb, Bef, Ctx, St0),
{Bis,Aft,St2} = match_cg(B, Fail, Int, St1),
CtxReg = fetch_var(Ctx, Bef),
{[{bs_restore2,CtxReg,{Ctx,Ivar}}|Mis] ++ Bis,Aft,St2}.
select_extract_int([{var,Tl}], Val, {integer,Sz}, U, Fs, Vf,
I, Vdb, Bef, Ctx, St) ->
Bits = U*Sz,
Bin = case member(big, Fs) of
true ->
<<Val:Bits>>;
false ->
true = member(little, Fs), %Assertion.
<<Val:Bits/little>>
end,
Bits = bit_size(Bin), %Assertion.
CtxReg = fetch_var(Ctx, Bef),
Is = if
Bits =:= 0 ->
[{bs_save2,CtxReg,{Ctx,Tl}}];
true ->
[{test,bs_match_string,{f,Vf},[CtxReg,Bin]},
{bs_save2,CtxReg,{Ctx,Tl}}]
end,
{Is,clear_dead(Bef, I, Vdb),St}.
select_extract_bin([{var,Hd},{var,Tl}], Size0, Unit, Type, Flags, Vf,
I, Vdb, Bef, Ctx, _Body, St) ->
SizeReg = get_bin_size_reg(Size0, Bef),
{Es,Aft} =
case vdb_find(Hd, Vdb) of
{_,_,Lhd} when Lhd =< I ->
%% The extracted value will not be used.
CtxReg = fetch_var(Ctx, Bef),
Live = max_reg(Bef#sr.reg),
Skip = build_skip_instr(Type, Vf, CtxReg, Live,
SizeReg, Unit, Flags),
{[Skip,{bs_save2,CtxReg,{Ctx,Tl}}],Bef};
{_,_,_} ->
Reg = put_reg(Hd, Bef#sr.reg),
Int1 = Bef#sr{reg=Reg},
Rhd = fetch_reg(Hd, Reg),
CtxReg = fetch_reg(Ctx, Reg),
Live = max_reg(Bef#sr.reg),
{[build_bs_instr(Type, Vf, CtxReg, Live, SizeReg,
Unit, Flags, Rhd),
{bs_save2,CtxReg,{Ctx,Tl}}],Int1}
end,
{Es,clear_dead(Aft, I, Vdb),St};
select_extract_bin([{var,Hd}], Size0, Unit, binary, Flags, Vf,
I, Vdb, Bef, Ctx, Body, St) ->
SizeReg = get_bin_size_reg(Size0, Bef),
{Es,Aft} =
case vdb_find(Hd, Vdb) of
{_,_,Lhd} when Lhd =< I ->
CtxReg = fetch_var(Ctx, Bef),
{case SizeReg =:= {atom,all} andalso is_context_unused(Body) of
true when Unit =:= 1 ->
[];
true ->
[{test,bs_test_unit,{f,Vf},[CtxReg,Unit]}];
false ->
[{test,bs_skip_bits2,{f,Vf},
[CtxReg,SizeReg,Unit,{field_flags,Flags}]}]
end,Bef};
{_,_,_} ->
case is_context_unused(Body) of
false ->
Reg = put_reg(Hd, Bef#sr.reg),
Int1 = Bef#sr{reg=Reg},
Rhd = fetch_reg(Hd, Reg),
CtxReg = fetch_reg(Ctx, Reg),
Name = bs_get_binary2,
Live = max_reg(Bef#sr.reg),
{[{test,Name,{f,Vf},Live,
[CtxReg,SizeReg,Unit,{field_flags,Flags}],Rhd}],
Int1};
true ->
%% Since the matching context will not be used again,
%% we can reuse its register. Reusing the register
%% opens some interesting optimizations in the
%% run-time system.
Reg0 = Bef#sr.reg,
CtxReg = fetch_reg(Ctx, Reg0),
Reg = replace_reg_contents(Ctx, Hd, Reg0),
Int1 = Bef#sr{reg=Reg},
Name = bs_get_binary2,
Live = max_reg(Int1#sr.reg),
{[{test,Name,{f,Vf},Live,
[CtxReg,SizeReg,Unit,{field_flags,Flags}],CtxReg}],
Int1}
end
end,
{Es,clear_dead(Aft, I, Vdb),St}.
%% is_context_unused(Ke) -> true | false
%% Simple heurististic to determine whether the code that follows will
%% use the current matching context again. (The information of liveness
%% calculcated by v3_life is too conservative to be useful for this purpose.)
%% 'true' means that the code that follows will definitely not use the context
%% again (because it is a block, not guard or matching code); 'false' that we
%% are not sure (there is either a guard, or more matching, either which may
%% reference the context again).
is_context_unused(#l{ke=Ke}) -> is_context_unused(Ke);
is_context_unused({block,_}) -> true;
is_context_unused(_) -> false.
select_bin_end(#l{ke={val_clause,{bin_end,Ctx},B}},
Ivar, Tf, Bef, St0) ->
{Bis,Aft,St2} = match_cg(B, Tf, Bef, St0),
CtxReg = fetch_var(Ctx, Bef),
{[{bs_restore2,CtxReg,{Ctx,Ivar}},
{test,bs_test_tail2,{f,Tf},[CtxReg,0]}|Bis],Aft,St2}.
get_bin_size_reg({var,V}, Bef) ->
fetch_var(V, Bef);
get_bin_size_reg(Literal, _Bef) ->
Literal.
build_bs_instr(Type, Vf, CtxReg, Live, SizeReg, Unit, Flags, Rhd) ->
{Format,Name} = case Type of
integer -> {plain,bs_get_integer2};
float -> {plain,bs_get_float2};
binary -> {plain,bs_get_binary2};
utf8 -> {utf,bs_get_utf8};
utf16 -> {utf,bs_get_utf16};
utf32 -> {utf,bs_get_utf32}
end,
case Format of
plain ->
{test,Name,{f,Vf},Live,
[CtxReg,SizeReg,Unit,{field_flags,Flags}],Rhd};
utf ->
{test,Name,{f,Vf},Live,
[CtxReg,{field_flags,Flags}],Rhd}
end.
build_skip_instr(Type, Vf, CtxReg, Live, SizeReg, Unit, Flags) ->
{Format,Name} = case Type of
utf8 -> {utf,bs_skip_utf8};
utf16 -> {utf,bs_skip_utf16};
utf32 -> {utf,bs_skip_utf32};
_ -> {plain,bs_skip_bits2}
end,
case Format of
plain ->
{test,Name,{f,Vf},[CtxReg,SizeReg,Unit,{field_flags,Flags}]};
utf ->
{test,Name,{f,Vf},[CtxReg,Live,{field_flags,Flags}]}
end.
select_val(#l{ke={val_clause,{tuple,Es},B},i=I,vdb=Vdb}, V, Vf, Bef, St0) ->
{Eis,Int,St1} = select_extract_tuple(V, Es, I, Vdb, Bef, St0),
{Bis,Aft,St2} = match_cg(B, Vf, Int, St1),
{length(Es),Eis ++ Bis,Aft,St2};
select_val(#l{ke={val_clause,{_,Val},B}}, _V, Vf, Bef, St0) ->
{Bis,Aft,St1} = match_cg(B, Vf, Bef, St0),
{Val,Bis,Aft,St1}.
%% select_extract_tuple(Src, [V], I, Vdb, StackReg, State) ->
%% {[E],StackReg,State}.
%% Extract tuple elements, but only if they do not immediately die.
select_extract_tuple(Src, Vs, I, Vdb, Bef, St) ->
F = fun ({var,V}, {Int0,Elem}) ->
case vdb_find(V, Vdb) of
{V,_,L} when L =< I -> {[], {Int0,Elem+1}};
_Other ->
Reg1 = put_reg(V, Int0#sr.reg),
Int1 = Int0#sr{reg=Reg1},
Rsrc = fetch_var(Src, Int1),
{[{get_tuple_element,Rsrc,Elem,fetch_reg(V, Reg1)}],
{Int1,Elem+1}}
end
end,
{Es,{Aft,_}} = flatmapfoldl(F, {Bef,0}, Vs),
{Es,Aft,St}.
select_extract_cons(Src, [{var,Hd}, {var,Tl}], I, Vdb, Bef, St) ->
{Es,Aft} = case {vdb_find(Hd, Vdb), vdb_find(Tl, Vdb)} of
{{_,_,Lhd}, {_,_,Ltl}} when Lhd =< I, Ltl =< I ->
%% Both head and tail are dead. No need to generate
%% any instruction.
{[], Bef};
_ ->
%% At least one of head and tail will be used,
%% but we must always fetch both. We will call
%% clear_dead/2 to allow reuse of the register
%% in case only of them is used.
Reg0 = put_reg(Tl, put_reg(Hd, Bef#sr.reg)),
Int0 = Bef#sr{reg=Reg0},
Rsrc = fetch_var(Src, Int0),
Rhd = fetch_reg(Hd, Reg0),
Rtl = fetch_reg(Tl, Reg0),
Int1 = clear_dead(Int0, I, Vdb),
{[{get_list,Rsrc,Rhd,Rtl}], Int1}
end,
{Es,Aft,St}.
guard_clause_cg(#l{ke={guard_clause,G,B},vdb=Vdb}, Fail, Bef, St0) ->
{Gis,Int,St1} = guard_cg(G, Fail, Vdb, Bef, St0),
{Bis,Aft,St} = match_cg(B, Fail, Int, St1),
{Gis ++ Bis,Aft,St}.
%% guard_cg(Guard, Fail, Vdb, StackReg, State) ->
%% {[Ainstr],StackReg,State}.
%% A guard is a boolean expression of tests. Tests return true or
%% false. A fault in a test causes the test to return false. Tests
%% never return the boolean, instead we generate jump code to go to
%% the correct exit point. Primops and tests all go to the next
%% instruction on success or jump to a failure label.
guard_cg(#l{ke={protected,Ts,Rs},i=I,vdb=Pdb}, Fail, _Vdb, Bef, St) ->
protected_cg(Ts, Rs, Fail, I, Pdb, Bef, St);
guard_cg(#l{ke={block,Ts},i=I,vdb=Bdb}, Fail, _Vdb, Bef, St) ->
guard_cg_list(Ts, Fail, I, Bdb, Bef, St);
guard_cg(#l{ke={test,Test,As},i=I,vdb=_Tdb}, Fail, Vdb, Bef, St) ->
test_cg(Test, As, Fail, I, Vdb, Bef, St);
guard_cg(G, _Fail, Vdb, Bef, St) ->
%%ok = io:fwrite("cg ~w: ~p~n", [?LINE,{G,Fail,Vdb,Bef}]),
{Gis,Aft,St1} = cg(G, Vdb, Bef, St),
%%ok = io:fwrite("cg ~w: ~p~n", [?LINE,{Aft}]),
{Gis,Aft,St1}.
%% protected_cg([Kexpr], [Ret], Fail, I, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%% Do a protected. Protecteds without return values are just done
%% for effect, the return value is not checked, success passes on to
%% the next instruction and failure jumps to Fail. If there are
%% return values then these must be set to 'false' on failure,
%% control always passes to the next instruction.
protected_cg(Ts, [], Fail, I, Vdb, Bef, St0) ->
%% Protect these calls, revert when done.
{Tis,Aft,St1} = guard_cg_list(Ts, Fail, I, Vdb, Bef,
St0#cg{bfail=Fail}),
{Tis,Aft,St1#cg{bfail=St0#cg.bfail}};
protected_cg(Ts, Rs, _Fail, I, Vdb, Bef, St0) ->
{Pfail,St1} = new_label(St0),
{Psucc,St2} = new_label(St1),
{Tis,Aft,St3} = guard_cg_list(Ts, Pfail, I, Vdb, Bef,
St2#cg{bfail=Pfail}),
%%ok = io:fwrite("cg ~w: ~p~n", [?LINE,{Rs,I,Vdb,Aft}]),
%% Set return values to false.
Mis = map(fun ({var,V}) -> {move,{atom,false},fetch_var(V, Aft)} end, Rs),
{Tis ++ [{jump,{f,Psucc}},
{label,Pfail}] ++ Mis ++ [{label,Psucc}],
Aft,St3#cg{bfail=St0#cg.bfail}}.
%% test_cg(TestName, Args, Fail, I, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%% Generate test instruction. Use explicit fail label here.
test_cg(Test, As, Fail, I, Vdb, Bef, St) ->
Args = cg_reg_args(As, Bef),
Aft = clear_dead(Bef, I, Vdb),
{[beam_utils:bif_to_test(Test, Args, {f,Fail})],Aft,St}.
%% guard_cg_list([Kexpr], Fail, I, Vdb, StackReg, St) ->
%% {[Ainstr],StackReg,St}.
guard_cg_list(Kes, Fail, I, Vdb, Bef, St0) ->
{Keis,{Aft,St1}} =
flatmapfoldl(fun (Ke, {Inta,Sta}) ->
{Keis,Intb,Stb} =
guard_cg(Ke, Fail, Vdb, Inta, Sta),
{Keis,{Intb,Stb}}
end, {Bef,St0}, need_heap(Kes, I)),
{Keis,Aft,St1}.
%% match_fmf(Fun, LastFail, State, [Clause]) -> {Is,Aft,State}.
%% This is a special flatmapfoldl for match code gen where we
%% generate a "failure" label for each clause. The last clause uses
%% an externally generated failure label, LastFail. N.B. We do not
%% know or care how the failure labels are used.
match_fmf(F, LastFail, St, [H]) ->
F(H, LastFail, St);
match_fmf(F, LastFail, St0, [H|T]) ->
{Fail,St1} = new_label(St0),
{R,Aft1,St2} = F(H, Fail, St1),
{Rs,Aft2,St3} = match_fmf(F, LastFail, St2, T),
{R ++ [{label,Fail}] ++ Rs,sr_merge(Aft1, Aft2),St3}.
%% call_cg(Func, [Arg], [Ret], Le, Vdb, StackReg, State) ->
%% {[Ainstr],StackReg,State}.
%% enter_cg(Func, [Arg], Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%% Call and enter first put the arguments into registers and save any
%% other registers, then clean up and compress the stack and set the
%% frame size. Finally the actual call is made. Call then needs the
%% return values filled in.
call_cg({var,_V} = Var, As, Rs, Le, Vdb, Bef, St0) ->
{Sis,Int} = cg_setup_call(As++[Var], Bef, Le#l.i, Vdb),
%% Put return values in registers.
Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
%% Build complete code and final stack/register state.
Arity = length(As),
{Frees,Aft} = free_dead(clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb)),
{Sis ++ Frees ++ [{call_fun,Arity}],Aft,
need_stack_frame(St0)};
call_cg({remote,Mod,Name}, As, Rs, Le, Vdb, Bef, St0)
when element(1, Mod) =:= var;
element(1, Name) =:= var ->
{Sis,Int} = cg_setup_call(As++[Mod,Name], Bef, Le#l.i, Vdb),
%% Put return values in registers.
Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
%% Build complete code and final stack/register state.
Arity = length(As),
Call = {apply,Arity},
St = need_stack_frame(St0),
%%{Call,St1} = build_call(Func, Arity, St0),
{Frees,Aft} = free_dead(clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb)),
{Sis ++ Frees ++ [Call],Aft,St};
call_cg(Func, As, Rs, Le, Vdb, Bef, St0) ->
case St0 of
#cg{bfail=Fail} when Fail =/= 0 ->
%% Inside a guard. The only allowed function call is to
%% erlang:error/1,2. We will generate the following code:
%%
%% jump FailureLabel
%% move {atom,ok} DestReg
%%
%% The 'move' instruction will never be executed, but we
%% generate it anyway in case the beam_validator is run
%% on unoptimized code.
{remote,{atom,erlang},{atom,error}} = Func, %Assertion.
[{var,DestVar}] = Rs,
Int0 = clear_dead(Bef, Le#l.i, Vdb),
Reg = put_reg(DestVar, Int0#sr.reg),
Int = Int0#sr{reg=Reg},
Dst = fetch_reg(DestVar, Reg),
{[{jump,{f,Fail}},{move,{atom,ok},Dst}],
clear_dead(Int, Le#l.i, Vdb),St0};
#cg{} ->
%% Ordinary function call in a function body.
{Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
%% Put return values in registers.
Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
%% Build complete code and final stack/register state.
Arity = length(As),
{Call,St1} = build_call(Func, Arity, St0),
{Frees,Aft} = free_dead(clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb)),
{Sis ++ Frees ++ Call,Aft,St1}
end.
build_call({remote,{atom,erlang},{atom,'!'}}, 2, St0) ->
{[send],need_stack_frame(St0)};
build_call({remote,{atom,Mod},{atom,Name}}, Arity, St0) ->
{[{call_ext,Arity,{extfunc,Mod,Name,Arity}}],need_stack_frame(St0)};
build_call(Name, Arity, St0) when is_atom(Name) ->
{Lbl,St1} = local_func_label(Name, Arity, need_stack_frame(St0)),
{[{call,Arity,{f,Lbl}}],St1}.
free_dead(#sr{stk=Stk0}=Aft) ->
{Instr,Stk} = free_dead(Stk0, 0, [], []),
{Instr,Aft#sr{stk=Stk}}.
free_dead([dead|Stk], Y, Instr, StkAcc) ->
%% Note: kill/1 is equivalent to init/1 (translated by beam_asm).
%% We use kill/1 to help further optimisation passes.
free_dead(Stk, Y+1, [{kill,{yy,Y}}|Instr], [free|StkAcc]);
free_dead([Any|Stk], Y, Instr, StkAcc) ->
free_dead(Stk, Y+1, Instr, [Any|StkAcc]);
free_dead([], _, Instr, StkAcc) -> {Instr,reverse(StkAcc)}.
enter_cg({var,_V} = Var, As, Le, Vdb, Bef, St0) ->
{Sis,Int} = cg_setup_call(As++[Var], Bef, Le#l.i, Vdb),
%% Build complete code and final stack/register state.
Arity = length(As),
{Sis ++ [{call_fun,Arity},return],
clear_dead(Int#sr{reg=clear_regs(Int#sr.reg)}, Le#l.i, Vdb),
need_stack_frame(St0)};
enter_cg({remote,Mod,Name}, As, Le, Vdb, Bef, St0)
when element(1, Mod) =:= var;
element(1, Name) =:= var ->
{Sis,Int} = cg_setup_call(As++[Mod,Name], Bef, Le#l.i, Vdb),
%% Build complete code and final stack/register state.
Arity = length(As),
Call = {apply_only,Arity},
St = need_stack_frame(St0),
{Sis ++ [Call],
clear_dead(Int#sr{reg=clear_regs(Int#sr.reg)}, Le#l.i, Vdb),
St};
enter_cg(Func, As, Le, Vdb, Bef, St0) ->
{Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
%% Build complete code and final stack/register state.
Arity = length(As),
{Call,St1} = build_enter(Func, Arity, St0),
{Sis ++ Call,
clear_dead(Int#sr{reg=clear_regs(Int#sr.reg)}, Le#l.i, Vdb),
St1}.
build_enter({remote,{atom,erlang},{atom,'!'}}, 2, St0) ->
{[send,return],need_stack_frame(St0)};
build_enter({remote,{atom,Mod},{atom,Name}}, Arity, St0) ->
St1 = case trap_bif(Mod, Name, Arity) of
true -> need_stack_frame(St0);
false -> St0
end,
{[{call_ext_only,Arity,{extfunc,Mod,Name,Arity}}],St1};
build_enter(Name, Arity, St0) when is_atom(Name) ->
{Lbl,St1} = local_func_label(Name, Arity, St0),
{[{call_only,Arity,{f,Lbl}}],St1}.
%% local_func_label(Name, Arity, State) -> {Label,State'}
%% local_func_label({Name,Arity}, State) -> {Label,State'}
%% Get the function entry label for a local function.
local_func_label(Name, Arity, St) ->
local_func_label({Name,Arity}, St).
local_func_label(Key, #cg{functable=Tab}=St0) ->
case gb_trees:lookup(Key, Tab) of
{value,Label} ->
{Label,St0};
none ->
{Label,St} = new_label(St0),
{Label,St#cg{functable=gb_trees:insert(Key, Label, Tab)}}
end.
%% need_stack_frame(State) -> State'
%% Make a note in the state that this function will need a stack frame.
need_stack_frame(#cg{need_frame=true}=St) -> St;
need_stack_frame(St) -> St#cg{need_frame=true}.
%% trap_bif(Mod, Name, Arity) -> true|false
%% Trap bifs that need a stack frame.
trap_bif(erlang, link, 1) -> true;
trap_bif(erlang, unlink, 1) -> true;
trap_bif(erlang, monitor_node, 2) -> true;
trap_bif(erlang, group_leader, 2) -> true;
trap_bif(erlang, exit, 2) -> true;
trap_bif(_, _, _) -> false.
%% bif_cg(Bif, [Arg], [Ret], Le, Vdb, StackReg, State) ->
%% {[Ainstr],StackReg,State}.
bif_cg(bs_context_to_binary=Instr, [Src0], [], Le, Vdb, Bef, St0) ->
[Src] = cg_reg_args([Src0], Bef),
case is_register(Src) of
false ->
{[],clear_dead(Bef, Le#l.i, Vdb), St0};
true ->
{[{Instr,Src}],clear_dead(Bef, Le#l.i, Vdb), St0}
end;
bif_cg(dsetelement, [Index0,Tuple0,New0], _Rs, Le, Vdb, Bef, St0) ->
[New,Tuple,{integer,Index1}] = cg_reg_args([New0,Tuple0,Index0], Bef),
Index = Index1-1,
{[{set_tuple_element,New,Tuple,Index}],
clear_dead(Bef, Le#l.i, Vdb), St0};
bif_cg({make_fun,Func,Arity,Index,Uniq}, As, Rs, Le, Vdb, Bef, St0) ->
%% This behaves more like a function call.
{Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
{FuncLbl,St1} = local_func_label(Func, Arity, St0),
MakeFun = {make_fun2,{f,FuncLbl},Index,Uniq,length(As)},
{Sis ++ [MakeFun],
clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb),
St1};
bif_cg(bs_init_writable=I, As, Rs, Le, Vdb, Bef, St) ->
%% This behaves like a function call.
{Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
{Sis++[I],clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb),St};
bif_cg(Bif, As, [{var,V}], Le, Vdb, Bef, St0) ->
Ars = cg_reg_args(As, Bef),
%% If we are inside a catch and in a body (not in guard) and the
%% BIF may fail, we must save everything that will be alive after
%% the catch (because the code after the code assumes that all
%% variables that are live are stored on the stack).
%%
%% Currently, we are somewhat pessimistic in
%% that we save any variable that will be live after this BIF call.
{Sis,Int0} = case St0#cg.in_catch andalso
St0#cg.bfail =:= 0 andalso
not erl_bifs:is_safe(erlang, Bif, length(As)) of
true -> adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb);
false -> {[],Bef}
end,
Int1 = clear_dead(Int0, Le#l.i, Vdb),
Reg = put_reg(V, Int1#sr.reg),
Int = Int1#sr{reg=Reg},
Dst = fetch_reg(V, Reg),
BifFail = {f,St0#cg.bfail},
{Sis++[{bif,Bif,BifFail,Ars,Dst}],
clear_dead(Int, Le#l.i, Vdb), St0}.
%% gc_bif_cg(Bif, [Arg], [Ret], Le, Vdb, StackReg, State) ->
%% {[Ainstr],StackReg,State}.
gc_bif_cg(Bif, As, [{var,V}], Le, Vdb, Bef, St0) ->
Ars = cg_reg_args(As, Bef),
%% If we are inside a catch and in a body (not in guard) and the
%% BIF may fail, we must save everything that will be alive after
%% the catch (because the code after the code assumes that all
%% variables that are live are stored on the stack).
%%
%% Currently, we are somewhat pessimistic in
%% that we save any variable that will be live after this BIF call.
{Sis,Int0} =
case St0#cg.in_catch andalso St0#cg.bfail =:= 0 of
true -> adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb);
false -> {[],Bef}
end,
Int1 = clear_dead(Int0, Le#l.i, Vdb),
Reg = put_reg(V, Int1#sr.reg),
Int = Int1#sr{reg=Reg},
Dst = fetch_reg(V, Reg),
BifFail = {f,St0#cg.bfail},
{Sis++[{gc_bif,Bif,BifFail,max_reg(Bef#sr.reg),Ars,Dst}],
clear_dead(Int, Le#l.i, Vdb), St0}.
%% recv_loop_cg(TimeOut, ReceiveVar, ReceiveMatch, TimeOutExprs,
%% [Ret], Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
recv_loop_cg(Te, Rvar, Rm, Tes, Rs, Le, Vdb, Bef, St0) ->
{Sis,Int0} = adjust_stack(Bef, Le#l.i, Le#l.i, Vdb),
Int1 = Int0#sr{reg=clear_regs(Int0#sr.reg)},
%% Get labels.
{Rl,St1} = new_label(St0),
{Tl,St2} = new_label(St1),
{Bl,St3} = new_label(St2),
St4 = St3#cg{break=Bl,recv=Rl}, %Set correct receive labels
{Ris,Raft,St5} = cg_recv_mesg(Rvar, Rm, Tl, Int1, St4),
{Wis,Taft,St6} = cg_recv_wait(Te, Tes, Le#l.i, Int1, St5),
Int2 = sr_merge(Raft, Taft), %Merge stack/registers
Reg = load_vars(Rs, Int2#sr.reg),
{Sis ++ Ris ++ [{label,Tl}] ++ Wis ++ [{label,Bl}],
clear_dead(Int2#sr{reg=Reg}, Le#l.i, Vdb),
St6#cg{break=St0#cg.break,recv=St0#cg.recv}}.
%% cg_recv_mesg( ) -> {[Ainstr],Aft,St}.
cg_recv_mesg({var,R}, Rm, Tl, Bef, St0) ->
Int0 = Bef#sr{reg=put_reg(R, Bef#sr.reg)},
Ret = fetch_reg(R, Int0#sr.reg),
%% Int1 = clear_dead(Int0, I, Rm#l.vdb),
Int1 = Int0,
{Mis,Int2,St1} = match_cg(Rm, none, Int1, St0),
{[{label,St1#cg.recv},{loop_rec,{f,Tl},Ret}|Mis],Int2,St1}.
%% cg_recv_wait(Te, Tes, I, Vdb, Int2, St3) -> {[Ainstr],Aft,St}.
cg_recv_wait({atom,infinity}, Tes, I, Bef, St0) ->
%% We know that the 'after' body will never be executed.
%% But to keep the stack and register information up to date,
%% we will generate the code for the 'after' body, and then discard it.
Int1 = clear_dead(Bef, I, Tes#l.vdb),
{_,Int2,St1} = cg_block(Tes#l.ke, Tes#l.i, Tes#l.vdb,
Int1#sr{reg=clear_regs(Int1#sr.reg)}, St0),
{[{wait,{f,St1#cg.recv}}],Int2,St1};
cg_recv_wait({integer,0}, Tes, _I, Bef, St0) ->
{Tis,Int,St1} = cg_block(Tes#l.ke, Tes#l.i, Tes#l.vdb, Bef, St0),
{[timeout|Tis],Int,St1};
cg_recv_wait(Te, Tes, I, Bef, St0) ->
Reg = cg_reg_arg(Te, Bef),
%% Must have empty registers here! Bug if anything in registers.
Int0 = clear_dead(Bef, I, Tes#l.vdb),
{Tis,Int,St1} = cg_block(Tes#l.ke, Tes#l.i, Tes#l.vdb,
Int0#sr{reg=clear_regs(Int0#sr.reg)}, St0),
{[{wait_timeout,{f,St1#cg.recv},Reg},timeout] ++ Tis,Int,St1}.
%% recv_next_cg(Le, Vdb, StackReg, St) -> {[Ainstr],StackReg,St}.
%% Use adjust stack to clear stack, but only need it for Aft.
recv_next_cg(Le, Vdb, Bef, St) ->
{Sis,Aft} = adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb),
{[{loop_rec_end,{f,St#cg.recv}}] ++ Sis,Aft,St}. %Joke
%% try_cg(TryBlock, [BodyVar], TryBody, [ExcpVar], TryHandler, [Ret],
%% Le, Vdb, StackReg, St) -> {[Ainstr],StackReg,St}.
try_cg(Ta, Vs, Tb, Evs, Th, Rs, Le, Vdb, Bef, St0) ->
{B,St1} = new_label(St0), %Body label
{H,St2} = new_label(St1), %Handler label
{E,St3} = new_label(St2), %End label
TryTag = Ta#l.i,
Int1 = Bef#sr{stk=put_catch(TryTag, Bef#sr.stk)},
TryReg = fetch_stack({catch_tag,TryTag}, Int1#sr.stk),
{Ais,Int2,St4} = cg(Ta, Vdb, Int1, St3#cg{break=B,in_catch=true}),
Int3 = Int2#sr{stk=drop_catch(TryTag, Int2#sr.stk)},
St5 = St4#cg{break=E,in_catch=St3#cg.in_catch},
{Bis,Baft,St6} = cg(Tb, Vdb, Int3#sr{reg=load_vars(Vs, Int3#sr.reg)}, St5),
{His,Haft,St7} = cg(Th, Vdb, Int3#sr{reg=load_vars(Evs, Int3#sr.reg)}, St6),
Int4 = sr_merge(Baft, Haft), %Merge stack/registers
Aft = Int4#sr{reg=load_vars(Rs, Int4#sr.reg)},
{[{'try',TryReg,{f,H}}] ++ Ais ++
[{label,B},{try_end,TryReg}] ++ Bis ++
[{label,H},{try_case,TryReg}] ++ His ++
[{label,E}],
clear_dead(Aft, Le#l.i, Vdb),
St7#cg{break=St0#cg.break}}.
try_enter_cg(Ta, Vs, Tb, Evs, Th, Le, Vdb, Bef, St0) ->
{B,St1} = new_label(St0), %Body label
{H,St2} = new_label(St1), %Handler label
TryTag = Ta#l.i,
Int1 = Bef#sr{stk=put_catch(TryTag, Bef#sr.stk)},
TryReg = fetch_stack({catch_tag,TryTag}, Int1#sr.stk),
{Ais,Int2,St3} = cg(Ta, Vdb, Int1, St2#cg{break=B,in_catch=true}),
Int3 = Int2#sr{stk=drop_catch(TryTag, Int2#sr.stk)},
St4 = St3#cg{in_catch=St2#cg.in_catch},
{Bis,Baft,St5} = cg(Tb, Vdb, Int3#sr{reg=load_vars(Vs, Int3#sr.reg)}, St4),
{His,Haft,St6} = cg(Th, Vdb, Int3#sr{reg=load_vars(Evs, Int3#sr.reg)}, St5),
Int4 = sr_merge(Baft, Haft), %Merge stack/registers
Aft = Int4,
{[{'try',TryReg,{f,H}}] ++ Ais ++
[{label,B},{try_end,TryReg}] ++ Bis ++
[{label,H},{try_case,TryReg}] ++ His,
clear_dead(Aft, Le#l.i, Vdb),
St6#cg{break=St0#cg.break}}.
%% catch_cg(CatchBlock, Ret, Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
catch_cg(C, {var,R}, Le, Vdb, Bef, St0) ->
{B,St1} = new_label(St0),
CatchTag = Le#l.i,
Int1 = Bef#sr{stk=put_catch(CatchTag, Bef#sr.stk)},
CatchReg = fetch_stack({catch_tag,CatchTag}, Int1#sr.stk),
{Cis,Int2,St2} = cg_block(C, Le#l.i, Le#l.vdb, Int1,
St1#cg{break=B,in_catch=true}),
[] = Int2#sr.reg, %Assertion.
Aft = Int2#sr{reg=[{0,R}],stk=drop_catch(CatchTag, Int2#sr.stk)},
{[{'catch',CatchReg,{f,B}}] ++ Cis ++
[{label,B},{catch_end,CatchReg}],
clear_dead(Aft, Le#l.i, Vdb),
St2#cg{break=St1#cg.break,in_catch=St1#cg.in_catch}}.
%% set_cg([Var], Constr, Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%% We have to be careful how a 'set' works. First the structure is
%% built, then it is filled and finally things can be cleared. The
%% annotation must reflect this and make sure that the return
%% variable is allocated first.
%%
%% put_list for constructing a cons is an atomic instruction
%% which can safely resuse one of the source registers as target.
%% Also binaries can reuse a source register as target.
set_cg([{var,R}], {cons,Es}, Le, Vdb, Bef, St) ->
[S1,S2] = map(fun ({var,V}) -> fetch_var(V, Bef);
(Other) -> Other
end, Es),
Int0 = clear_dead(Bef, Le#l.i, Vdb),
Int1 = Int0#sr{reg=put_reg(R, Int0#sr.reg)},
Ret = fetch_reg(R, Int1#sr.reg),
{[{put_list,S1,S2,Ret}], Int1, St};
set_cg([{var,R}], {binary,Segs}, Le, Vdb, Bef,
#cg{in_catch=InCatch, bfail=Bfail}=St) ->
Int0 = Bef#sr{reg=put_reg(R, Bef#sr.reg)},
Target = fetch_reg(R, Int0#sr.reg),
Fail = {f,Bfail},
Temp = find_scratch_reg(Int0#sr.reg),
PutCode = cg_bin_put(Segs, Fail, Bef),
{Sis,Int1} =
case InCatch of
true -> adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb);
false -> {[],Int0}
end,
MaxRegs = max_reg(Bef#sr.reg),
Aft = clear_dead(Int1, Le#l.i, Vdb),
Code = cg_binary(PutCode, Target, Temp, Fail, MaxRegs, Le#l.a),
{Sis++Code,Aft,St};
set_cg([{var,R}], Con, Le, Vdb, Bef, St) ->
%% Find a place for the return register first.
Int = Bef#sr{reg=put_reg(R, Bef#sr.reg)},
Ret = fetch_reg(R, Int#sr.reg),
Ais = case Con of
{tuple,Es} ->
[{put_tuple,length(Es),Ret}] ++ cg_build_args(Es, Bef);
{var,V} -> % Normally removed by kernel optimizer.
[{move,fetch_var(V, Int),Ret}];
Other ->
[{move,Other,Ret}]
end,
{Ais,clear_dead(Int, Le#l.i, Vdb),St};
set_cg([], {binary,Segs}, Le, Vdb, Bef, St) ->
Fail = {f,St#cg.bfail},
Target = find_scratch_reg(Bef#sr.reg),
Temp = find_scratch_reg(put_reg(Target, Bef#sr.reg)),
PutCode = cg_bin_put(Segs, Fail, Bef),
MaxRegs = max_reg(Bef#sr.reg),
Code = cg_binary(PutCode, Target, Temp, Fail, MaxRegs, Le#l.a),
Aft = clear_dead(Bef, Le#l.i, Vdb),
{Code,Aft,St};
set_cg([], _, Le, Vdb, Bef, St) ->
%% This should have been stripped by compiler, just cleanup.
{[],clear_dead(Bef, Le#l.i, Vdb), St}.
%%%
%%% Code generation for constructing binaries.
%%%
cg_binary([{bs_put_binary,Fail,{atom,all},U,_Flags,Src}|PutCode],
Target, Temp, Fail, MaxRegs, Anno) ->
Live = cg_live(Target, MaxRegs),
SzCode = cg_bitstr_size(PutCode, Target, Temp, Fail, Live),
BinFlags = {field_flags,[]},
Code = SzCode ++
[case member(single_use, Anno) of
true ->
{bs_private_append,Fail,Target,U,Src,BinFlags,Target};
false ->
{bs_append,Fail,Target,0,MaxRegs,U,Src,BinFlags,Target}
end] ++ PutCode,
cg_bin_opt(Code);
cg_binary(PutCode, Target, Temp, Fail, MaxRegs, _Anno) ->
Live = cg_live(Target, MaxRegs),
{InitOp,SzCode} = cg_binary_size(PutCode, Target, Temp, Fail, Live),
Code = SzCode ++ [{InitOp,Fail,Target,0,MaxRegs,
{field_flags,[]},Target}|PutCode],
cg_bin_opt(Code).
cg_live({x,X}, MaxRegs) when X =:= MaxRegs -> MaxRegs+1;
cg_live({x,X}, MaxRegs) when X < MaxRegs -> MaxRegs.
%% Generate code that calculate the size of the bitstr to be
%% built in BITS.
cg_bitstr_size(PutCode, Target, Temp, Fail, Live) ->
{Bits,Es} = cg_bitstr_size_1(PutCode, 0, []),
reverse(cg_gen_binsize(Es, Target, Temp, Fail, Live,
[{move,{integer,Bits},Target}])).
cg_bitstr_size_1([{bs_put_utf8,_,_,Src}|Next], Bits, Acc) ->
cg_bitstr_size_1(Next, Bits, [{'*',{bs_utf8_size,Src},8}|Acc]);
cg_bitstr_size_1([{bs_put_utf16,_,_,Src}|Next], Bits, Acc) ->
cg_bitstr_size_1(Next, Bits, [{'*',{bs_utf16_size,Src},8}|Acc]);
cg_bitstr_size_1([{bs_put_utf32,_,_,_}|Next], Bits, Acc) ->
cg_bitstr_size_1(Next, Bits+32, Acc);
cg_bitstr_size_1([{_,_,S,U,_,Src}|Next], Bits, Acc) ->
case S of
{integer,N} -> cg_bitstr_size_1(Next, Bits+N*U, Acc);
{atom,all} -> cg_bitstr_size_1(Next, Bits, [{bit_size,Src}|Acc]);
_ when U =:= 1 -> cg_bitstr_size_1(Next, Bits, [S|Acc]);
_ -> cg_bitstr_size_1(Next, Bits, [{'*',S,U}|Acc])
end;
cg_bitstr_size_1([], Bits, Acc) -> {Bits,Acc}.
%% Generate code that calculate the size of the bitstr to be
%% built in BYTES or BITS (depending on what is easiest).
cg_binary_size(PutCode, Target, Temp, Fail, Live) ->
{InitInstruction,Szs} = cg_binary_size_1(PutCode, 0, []),
SizeExpr = reverse(cg_gen_binsize(Szs, Target, Temp, Fail, Live, [{move,{integer,0},Target}])),
{InitInstruction,SizeExpr}.
cg_binary_size_1([{bs_put_utf8,_Fail,_Flags,Src}|T], Bits, Acc) ->
cg_binary_size_1(T, Bits, [{8,{bs_utf8_size,Src}}|Acc]);
cg_binary_size_1([{bs_put_utf16,_Fail,_Flags,Src}|T], Bits, Acc) ->
cg_binary_size_1(T, Bits, [{8,{bs_utf16_size,Src}}|Acc]);
cg_binary_size_1([{bs_put_utf32,_Fail,_Flags,_Src}|T], Bits, Acc) ->
cg_binary_size_1(T, Bits+32, Acc);
cg_binary_size_1([{_Put,_Fail,S,U,_Flags,Src}|T], Bits, Acc) ->
cg_binary_size_2(S, U, Src, T, Bits, Acc);
cg_binary_size_1([], Bits, Acc) ->
Bytes = Bits div 8,
RemBits = Bits rem 8,
Sizes0 = sort([{1,{integer,RemBits}},{8,{integer,Bytes}}|Acc]),
Sizes = filter(fun({_,{integer,0}}) -> false;
(_) -> true end, Sizes0),
case Sizes of
[{1,_}|_] ->
{bs_init_bits,cg_binary_bytes_to_bits(Sizes, [])};
[{8,_}|_] ->
{bs_init2,[E || {8,E} <- Sizes]};
[] ->
{bs_init_bits,[]}
end.
cg_binary_size_2({integer,N}, U, _, Next, Bits, Acc) ->
cg_binary_size_1(Next, Bits+N*U, Acc);
cg_binary_size_2({atom,all}, U, E, Next, Bits, Acc) ->
if
U rem 8 =:= 0 ->
cg_binary_size_1(Next, Bits, [{8,{byte_size,E}}|Acc]);
true ->
cg_binary_size_1(Next, Bits, [{1,{bit_size,E}}|Acc])
end;
cg_binary_size_2(Reg, 1, _, Next, Bits, Acc) ->
cg_binary_size_1(Next, Bits, [{1,Reg}|Acc]);
cg_binary_size_2(Reg, 8, _, Next, Bits, Acc) ->
cg_binary_size_1(Next, Bits, [{8,Reg}|Acc]);
cg_binary_size_2(Reg, U, _, Next, Bits, Acc) ->
cg_binary_size_1(Next, Bits, [{1,{'*',Reg,U}}|Acc]).
cg_binary_bytes_to_bits([{8,{integer,N}}|T], Acc) ->
cg_binary_bytes_to_bits(T, [{integer,8*N}|Acc]);
cg_binary_bytes_to_bits([{8,{byte_size,Reg}}|T], Acc) ->
cg_binary_bytes_to_bits(T, [{bit_size,Reg}|Acc]);
cg_binary_bytes_to_bits([{8,Reg}|T], Acc) ->
cg_binary_bytes_to_bits(T, [{'*',Reg,8}|Acc]);
cg_binary_bytes_to_bits([{1,Sz}|T], Acc) ->
cg_binary_bytes_to_bits(T, [Sz|Acc]);
cg_binary_bytes_to_bits([], Acc) ->
cg_binary_bytes_to_bits_1(sort(Acc)).
cg_binary_bytes_to_bits_1([{integer,I},{integer,J}|T]) ->
cg_binary_bytes_to_bits_1([{integer,I+J}|T]);
cg_binary_bytes_to_bits_1([H|T]) ->
[H|cg_binary_bytes_to_bits_1(T)];
cg_binary_bytes_to_bits_1([]) -> [].
cg_gen_binsize([{'*',{bs_utf8_size,Src},B}|T], Target, Temp, Fail, Live, Acc) ->
Size = {bs_utf8_size,Fail,Src,Temp},
Add = {bs_add,Fail,[Target,Temp,B],Target},
cg_gen_binsize(T, Target, Temp, Fail, Live,
[Add,Size|Acc]);
cg_gen_binsize([{'*',{bs_utf16_size,Src},B}|T], Target, Temp, Fail, Live, Acc) ->
Size = {bs_utf16_size,Fail,Src,Temp},
Add = {bs_add,Fail,[Target,Temp,B],Target},
cg_gen_binsize(T, Target, Temp, Fail, Live,
[Add,Size|Acc]);
cg_gen_binsize([{'*',A,B}|T], Target, Temp, Fail, Live, Acc) ->
cg_gen_binsize(T, Target, Temp, Fail, Live,
[{bs_add,Fail,[Target,A,B],Target}|Acc]);
cg_gen_binsize([{bit_size,B}|T], Target, Temp, Fail, Live, Acc) ->
cg_gen_binsize([Temp|T], Target, Temp, Fail, Live,
[{gc_bif,bit_size,Fail,Live,[B],Temp}|Acc]);
cg_gen_binsize([{byte_size,B}|T], Target, Temp, Fail, Live, Acc) ->
cg_gen_binsize([Temp|T], Target, Temp, Fail, Live,
[{gc_bif,byte_size,Fail,Live,[B],Temp}|Acc]);
cg_gen_binsize([{bs_utf8_size,B}|T], Target, Temp, Fail, Live, Acc) ->
cg_gen_binsize([Temp|T], Target, Temp, Fail, Live,
[{bs_utf8_size,Fail,B,Temp}|Acc]);
cg_gen_binsize([{bs_utf16_size,B}|T], Target, Temp, Fail, Live, Acc) ->
cg_gen_binsize([Temp|T], Target, Temp, Fail, Live,
[{bs_utf16_size,Fail,B,Temp}|Acc]);
cg_gen_binsize([E0|T], Target, Temp, Fail, Live, Acc) ->
cg_gen_binsize(T, Target, Temp, Fail, Live,
[{bs_add,Fail,[Target,E0,1],Target}|Acc]);
cg_gen_binsize([], _, _, _, _, Acc) -> Acc.
%% cg_bin_opt(Code0) -> Code
%% Optimize the size calculations for binary construction.
cg_bin_opt([{move,Size,D},{bs_append,Fail,D,Extra,Regs0,U,Bin,Flags,D}|Is]) ->
Regs = cg_bo_newregs(Regs0, D),
cg_bin_opt([{bs_append,Fail,Size,Extra,Regs,U,Bin,Flags,D}|Is]);
cg_bin_opt([{move,Size,D},{bs_private_append,Fail,D,U,Bin,Flags,D}|Is]) ->
cg_bin_opt([{bs_private_append,Fail,Size,U,Bin,Flags,D}|Is]);
cg_bin_opt([{move,{integer,0},D},{bs_add,_,[D,{integer,_}=S,1],Dst}|Is]) ->
cg_bin_opt([{move,S,Dst}|Is]);
cg_bin_opt([{move,{integer,0},D},{bs_add,Fail,[D,S,U],Dst}|Is]) ->
cg_bin_opt([{bs_add,Fail,[{integer,0},S,U],Dst}|Is]);
cg_bin_opt([{move,{integer,Bytes},D},{Op,Fail,D,Extra,Regs0,Flags,D}|Is])
when Op =:= bs_init2; Op =:= bs_init_bits ->
Regs = cg_bo_newregs(Regs0, D),
cg_bin_opt([{Op,Fail,Bytes,Extra,Regs,Flags,D}|Is]);
cg_bin_opt([{move,Src1,Dst},{bs_add,Fail,[Dst,Src2,U],Dst}|Is]) ->
cg_bin_opt([{bs_add,Fail,[Src1,Src2,U],Dst}|Is]);
cg_bin_opt([I|Is]) ->
[I|cg_bin_opt(Is)];
cg_bin_opt([]) -> [].
cg_bo_newregs(R, {x,X}) when R-1 =:= X -> R-1;
cg_bo_newregs(R, _) -> R.
%% Common for new and old binary code generation.
cg_bin_put({bin_seg,[],S0,U,T,Fs,[E0,Next]}, Fail, Bef) ->
S1 = case S0 of
{var,Sv} -> fetch_var(Sv, Bef);
_ -> S0
end,
E1 = case E0 of
{var,V} -> fetch_var(V, Bef);
Other -> Other
end,
{Format,Op} = case T of
integer -> {plain,bs_put_integer};
utf8 -> {utf,bs_put_utf8};
utf16 -> {utf,bs_put_utf16};
utf32 -> {utf,bs_put_utf32};
binary -> {plain,bs_put_binary};
float -> {plain,bs_put_float}
end,
case Format of
plain ->
[{Op,Fail,S1,U,{field_flags,Fs},E1}|cg_bin_put(Next, Fail, Bef)];
utf ->
[{Op,Fail,{field_flags,Fs},E1}|cg_bin_put(Next, Fail, Bef)]
end;
cg_bin_put({bin_end,[]}, _, _) -> [].
cg_build_args(As, Bef) ->
map(fun ({var,V}) -> {put,fetch_var(V, Bef)};
(Other) -> {put,Other}
end, As).
%% return_cg([Val], Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%% break_cg([Val], Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%% These are very simple, just put return/break values in registers
%% from 0, then return/break. Use the call setup to clean up stack,
%% but must clear registers to ensure sr_merge works correctly.
return_cg(Rs, Le, Vdb, Bef, St) ->
{Ms,Int} = cg_setup_call(Rs, Bef, Le#l.i, Vdb),
{Ms ++ [return],Int#sr{reg=clear_regs(Int#sr.reg)},St}.
break_cg(Bs, Le, Vdb, Bef, St) ->
{Ms,Int} = cg_setup_call(Bs, Bef, Le#l.i, Vdb),
{Ms ++ [{jump,{f,St#cg.break}}],
Int#sr{reg=clear_regs(Int#sr.reg)},St}.
guard_break_cg(Bs, Locked, #l{i=I}, Vdb, #sr{reg=Reg0}=Bef, St) ->
RegLocked = get_locked_regs(Reg0, Locked),
#sr{reg=Reg1} = Int = clear_dead(Bef#sr{reg=RegLocked}, I, Vdb),
Reg2 = trim_free(Reg1),
NumLocked = length(Reg2),
Moves0 = gen_moves(Bs, Bef, NumLocked, []),
Moves = order_moves(Moves0, find_scratch_reg(RegLocked)),
{BreakVars,_} = mapfoldl(fun(_, RegNum) ->
{{RegNum,gbreakvar},RegNum+1}
end, length(Reg2), Bs),
Reg = Reg2 ++ BreakVars,
Aft = Int#sr{reg=Reg},
{Moves ++ [{jump,{f,St#cg.break}}],Aft,St}.
get_locked_regs([R|Rs0], Preserve) ->
case {get_locked_regs(Rs0, Preserve),R} of
{[],{_,V}} ->
case lists:member(V, Preserve) of
true -> [R];
false -> []
end;
{[],_} ->
[];
{Rs,_} ->
[R|Rs]
end;
get_locked_regs([], _) -> [].
%% cg_reg_arg(Arg0, Info) -> Arg
%% cg_reg_args([Arg0], Info) -> [Arg]
%% Convert argument[s] into registers. Literal values are returned unchanged.
cg_reg_args(As, Bef) -> [cg_reg_arg(A, Bef) || A <- As].
cg_reg_arg({var,V}, Bef) -> fetch_var(V, Bef);
cg_reg_arg(Literal, _) -> Literal.
%% cg_setup_call([Arg], Bef, Cur, Vdb) -> {[Instr],Aft}.
%% Do the complete setup for a call/enter.
cg_setup_call(As, Bef, I, Vdb) ->
{Ms,Int0} = cg_call_args(As, Bef, I, Vdb),
%% Have set up arguments, can now clean up, compress and save to stack.
Int1 = Int0#sr{stk=clear_dead_stk(Int0#sr.stk, I, Vdb),res=[]},
{Sis,Int2} = adjust_stack(Int1, I, I+1, Vdb),
{Ms ++ Sis,Int2}.
%% cg_call_args([Arg], SrState) -> {[Instr],SrState}.
%% Setup the arguments to a call/enter/bif. Put the arguments into
%% consecutive registers starting at {x,0} moving any data which
%% needs to be saved. Return a modified SrState structure with the
%% new register contents. N.B. the resultant register info will
%% contain non-variable values when there are non-variable values.
%%
%% This routine is complicated by unsaved values in x registers.
%% We'll move away any unsaved values that are in the registers
%% to be overwritten by the arguments.
cg_call_args(As, Bef, I, Vdb) ->
Regs0 = load_arg_regs(Bef#sr.reg, As),
Unsaved = unsaved_registers(Regs0, Bef#sr.stk, I, I+1, Vdb),
{UnsavedMoves,Regs} = move_unsaved(Unsaved, Bef#sr.reg, Regs0),
Moves0 = gen_moves(As, Bef),
Moves = order_moves(Moves0, find_scratch_reg(Regs)),
{UnsavedMoves ++ Moves,Bef#sr{reg=Regs}}.
%% load_arg_regs([Reg], Arguments) -> [Reg]
%% Update the register descriptor to include the arguments (from {x,0}
%% and upwards). Values in argument register are overwritten.
%% Values in x registers above the arguments are preserved.
load_arg_regs(Regs, As) -> load_arg_regs(Regs, As, 0).
load_arg_regs([_|Rs], [{var,V}|As], I) -> [{I,V}|load_arg_regs(Rs, As, I+1)];
load_arg_regs([_|Rs], [A|As], I) -> [{I,A}|load_arg_regs(Rs, As, I+1)];
load_arg_regs([], [{var,V}|As], I) -> [{I,V}|load_arg_regs([], As, I+1)];
load_arg_regs([], [A|As], I) -> [{I,A}|load_arg_regs([], As, I+1)];
load_arg_regs(Rs, [], _) -> Rs.
%% Returns the variables must be saved and are currently in the
%% x registers that are about to be overwritten by the arguments.
unsaved_registers(Regs, Stk, Fb, Lf, Vdb) ->
[V || {V,F,L} <- Vdb,
F < Fb,
L >= Lf,
not on_stack(V, Stk),
not in_reg(V, Regs)].
in_reg(V, Regs) -> keymember(V, 2, Regs).
%% Move away unsaved variables from the registers that are to be
%% overwritten by the arguments.
move_unsaved(Vs, OrigRegs, NewRegs) ->
move_unsaved(Vs, OrigRegs, NewRegs, []).
move_unsaved([V|Vs], OrigRegs, NewRegs0, Acc) ->
NewRegs = put_reg(V, NewRegs0),
Src = fetch_reg(V, OrigRegs),
Dst = fetch_reg(V, NewRegs),
move_unsaved(Vs, OrigRegs, NewRegs, [{move,Src,Dst}|Acc]);
move_unsaved([], _, Regs, Acc) -> {Acc,Regs}.
%% gen_moves(As, Sr)
%% Generate the basic move instruction to move the arguments
%% to their proper registers. The list will be sorted on
%% destinations. (I.e. the move to {x,0} will be first --
%% see the comment to order_moves/2.)
gen_moves(As, Sr) -> gen_moves(As, Sr, 0, []).
gen_moves([{var,V}|As], Sr, I, Acc) ->
case fetch_var(V, Sr) of
{x,I} -> gen_moves(As, Sr, I+1, Acc);
Reg -> gen_moves(As, Sr, I+1, [{move,Reg,{x,I}}|Acc])
end;
gen_moves([A|As], Sr, I, Acc) ->
gen_moves(As, Sr, I+1, [{move,A,{x,I}}|Acc]);
gen_moves([], _, _, Acc) -> lists:keysort(3, Acc).
%% order_moves([Move], ScratchReg) -> [Move]
%% Orders move instruction so that source registers are not
%% destroyed before they are used. If there are cycles
%% (such as {move,{x,0},{x,1}}, {move,{x,1},{x,1}}),
%% the scratch register is used to break up the cycle.
%% If possible, the first move of the input list is placed
%% last in the result list (to make the move to {x,0} occur
%% just before the call to allow the Beam loader to coalesce
%% the instructions).
order_moves(Ms, Scr) -> order_moves(Ms, Scr, []).
order_moves([{move,_,_}=M|Ms0], ScrReg, Acc0) ->
{Chain,Ms} = collect_chain(Ms0, [M], ScrReg),
Acc = reverse(Chain, Acc0),
order_moves(Ms, ScrReg, Acc);
order_moves([], _, Acc) -> Acc.
collect_chain(Ms, Path, ScrReg) ->
collect_chain(Ms, Path, [], ScrReg).
collect_chain([{move,Src,Same}=M|Ms0], [{move,Same,_}|_]=Path, Others, ScrReg) ->
case lists:keyfind(Src, 3, Path) of
false ->
collect_chain(reverse(Others, Ms0), [M|Path], [], ScrReg);
_ -> % We have a cycle.
{break_up_cycle(M, Path, ScrReg),reverse(Others, Ms0)}
end;
collect_chain([M|Ms], Path, Others, ScrReg) ->
collect_chain(Ms, Path, [M|Others], ScrReg);
collect_chain([], Path, Others, _) ->
{Path,Others}.
break_up_cycle({move,Src,_}=M, Path, ScrReg) ->
[{move,ScrReg,Src},M|break_up_cycle1(Src, Path, ScrReg)].
break_up_cycle1(Dst, [{move,Src,Dst}|Path], ScrReg) ->
[{move,Src,ScrReg}|Path];
break_up_cycle1(Dst, [M|Path], LastMove) ->
[M|break_up_cycle1(Dst, Path, LastMove)].
%% clear_dead(Sr, Until, Vdb) -> Aft.
%% Remove all variables in Sr which have died AT ALL so far.
clear_dead(Sr, Until, Vdb) ->
Sr#sr{reg=clear_dead_reg(Sr, Until, Vdb),
stk=clear_dead_stk(Sr#sr.stk, Until, Vdb)}.
clear_dead_reg(Sr, Until, Vdb) ->
Reg = map(fun ({_I,V} = IV) ->
case vdb_find(V, Vdb) of
{V,_,L} when L > Until -> IV;
_ -> free %Remove anything else
end;
({reserved,_I,_V} = Reserved) -> Reserved;
(free) -> free
end, Sr#sr.reg),
reserve(Sr#sr.res, Reg, Sr#sr.stk).
clear_dead_stk(Stk, Until, Vdb) ->
map(fun ({V} = T) ->
case vdb_find(V, Vdb) of
{V,_,L} when L > Until -> T;
_ -> dead %Remove anything else
end;
(free) -> free;
(dead) -> dead
end, Stk).
%% sr_merge(Sr1, Sr2) -> Sr.
%% Merge two stack/register states keeping the longest of both stack
%% and register. Perform consistency check on both, elements must be
%% the same. Allow frame size 'void' to make easy creation of
%% "empty" frame.
sr_merge(#sr{reg=R1,stk=S1,res=[]}, #sr{reg=R2,stk=S2,res=[]}) ->
#sr{reg=longest(R1, R2),stk=longest(S1, S2),res=[]};
sr_merge(void, S2) -> S2#sr{res=[]}.
longest([H|T1], [H|T2]) -> [H|longest(T1, T2)];
longest([dead|T1], [free|T2]) -> [dead|longest(T1, T2)];
longest([free|T1], [dead|T2]) -> [dead|longest(T1, T2)];
longest([dead|_] = L, []) -> L;
longest([], [dead|_] = L) -> L;
longest([free|_] = L, []) -> L;
longest([], [free|_] = L) -> L;
longest([], []) -> [].
trim_free([R|Rs0]) ->
case {trim_free(Rs0),R} of
{[],free} -> [];
{Rs,R} -> [R|Rs]
end;
trim_free([]) -> [].
%% adjust_stack(Bef, FirstBefore, LastFrom, Vdb) -> {[Ainstr],Aft}.
%% Do complete stack adjustment by compressing stack and adding
%% variables to be saved. Try to optimise ordering on stack by
%% having reverse order to their lifetimes.
%%
%% In Beam, there is a fixed stack frame and no need to do stack compression.
adjust_stack(Bef, Fb, Lf, Vdb) ->
Stk0 = Bef#sr.stk,
{Stk1,Saves} = save_stack(Stk0, Fb, Lf, Vdb),
{saves(Saves, Bef#sr.reg, Stk1),
Bef#sr{stk=Stk1}}.
%% save_stack(Stack, FirstBefore, LastFrom, Vdb) -> {[SaveVar],NewStack}.
%% Save variables which are used past current point and which are not
%% already on the stack.
save_stack(Stk0, Fb, Lf, Vdb) ->
%% New variables that are in use but not on stack.
New = [VFL || {V,F,L} = VFL <- Vdb,
F < Fb,
L >= Lf,
not on_stack(V, Stk0)],
%% Add new variables that are not just dropped immediately.
%% N.B. foldr works backwards from the end!!
Saves = [V || {V,_,_} <- keysort(3, New)],
Stk1 = foldr(fun (V, Stk) -> put_stack(V, Stk) end, Stk0, Saves),
{Stk1,Saves}.
%% saves([SaveVar], Reg, Stk) -> [{move,Reg,Stk}].
%% Generate move instructions to save variables onto stack. The
%% stack/reg info used is that after the new stack has been made.
saves(Ss, Reg, Stk) ->
[{move,fetch_reg(V, Reg),fetch_stack(V, Stk)} || V <- Ss].
%% fetch_var(VarName, StkReg) -> r{R} | sp{Sp}.
%% find_var(VarName, StkReg) -> ok{r{R} | sp{Sp}} | error.
%% Fetch/find a variable in either the registers or on the
%% stack. Fetch KNOWS it's there.
fetch_var(V, Sr) ->
case find_reg(V, Sr#sr.reg) of
{ok,R} -> R;
error -> fetch_stack(V, Sr#sr.stk)
end.
% find_var(V, Sr) ->
% case find_reg(V, Sr#sr.reg) of
% {ok,R} -> {ok,R};
% error ->
% case find_stack(V, Sr#sr.stk) of
% {ok,S} -> {ok,S};
% error -> error
% end
% end.
load_vars(Vs, Regs) ->
foldl(fun ({var,V}, Rs) -> put_reg(V, Rs) end, Regs, Vs).
%% put_reg(Val, Regs) -> Regs.
%% free_reg(Val, Regs) -> Regs.
%% find_reg(Val, Regs) -> ok{r{R}} | error.
%% fetch_reg(Val, Regs) -> r{R}.
%% Functions to interface the registers.
%% put_reg puts a value into a free register,
%% load_reg loads a value into a fixed register
%% free_reg frees a register containing a specific value.
% put_regs(Vs, Rs) -> foldl(fun put_reg/2, Rs, Vs).
put_reg(V, Rs) -> put_reg_1(V, Rs, 0).
put_reg_1(V, [free|Rs], I) -> [{I,V}|Rs];
put_reg_1(V, [{reserved,I,V}|Rs], I) -> [{I,V}|Rs];
put_reg_1(V, [R|Rs], I) -> [R|put_reg_1(V, Rs, I+1)];
put_reg_1(V, [], I) -> [{I,V}].
% free_reg(V, [{I,V}|Rs]) -> [free|Rs];
% free_reg(V, [R|Rs]) -> [R|free_reg(V, Rs)];
% free_reg(V, []) -> [].
fetch_reg(V, [{I,V}|_]) -> {x,I};
fetch_reg(V, [_|SRs]) -> fetch_reg(V, SRs).
find_reg(V, [{I,V}|_]) -> {ok,{x,I}};
find_reg(V, [_|SRs]) -> find_reg(V, SRs);
find_reg(_, []) -> error.
%% For the bit syntax, we need a scratch register if we are constructing
%% a binary that will not be used.
find_scratch_reg(Rs) -> find_scratch_reg(Rs, 0).
find_scratch_reg([free|_], I) -> {x,I};
find_scratch_reg([_|Rs], I) -> find_scratch_reg(Rs, I+1);
find_scratch_reg([], I) -> {x,I}.
%%copy_reg(Val, R, Regs) -> load_reg(Val, R, Regs).
%%move_reg(Val, R, Regs) -> load_reg(Val, R, free_reg(Val, Regs)).
replace_reg_contents(Old, New, [{I,Old}|Rs]) -> [{I,New}|Rs];
replace_reg_contents(Old, New, [R|Rs]) -> [R|replace_reg_contents(Old, New, Rs)].
%%clear_regs(Regs) -> map(fun (R) -> free end, Regs).
clear_regs(_) -> [].
max_reg(Regs) ->
foldl(fun ({I,_}, _) -> I;
(_, Max) -> Max end,
-1, Regs) + 1.
%% put_stack(Val, [{Val}]) -> [{Val}].
%% fetch_stack(Var, Stk) -> sp{S}.
%% find_stack(Var, Stk) -> ok{sp{S}} | error.
%% Functions to interface the stack.
put_stack(Val, []) -> [{Val}];
put_stack(Val, [dead|Stk]) -> [{Val}|Stk];
put_stack(Val, [free|Stk]) -> [{Val}|Stk];
put_stack(Val, [NotFree|Stk]) -> [NotFree|put_stack(Val, Stk)].
put_stack_carefully(Val, Stk0) ->
case catch put_stack_carefully1(Val, Stk0) of
error -> error;
Stk1 when is_list(Stk1) -> Stk1
end.
put_stack_carefully1(_, []) -> throw(error);
put_stack_carefully1(Val, [dead|Stk]) -> [{Val}|Stk];
put_stack_carefully1(Val, [free|Stk]) -> [{Val}|Stk];
put_stack_carefully1(Val, [NotFree|Stk]) ->
[NotFree|put_stack_carefully1(Val, Stk)].
fetch_stack(Var, Stk) -> fetch_stack(Var, Stk, 0).
fetch_stack(V, [{V}|_], I) -> {yy,I};
fetch_stack(V, [_|Stk], I) -> fetch_stack(V, Stk, I+1).
% find_stack(Var, Stk) -> find_stack(Var, Stk, 0).
% find_stack(V, [{V}|Stk], I) -> {ok,{yy,I}};
% find_stack(V, [O|Stk], I) -> find_stack(V, Stk, I+1);
% find_stack(V, [], I) -> error.
on_stack(V, Stk) -> keymember(V, 1, Stk).
is_register({x,_}) -> true;
is_register({yy,_}) -> true;
is_register(_) -> false.
%% put_catch(CatchTag, Stack) -> Stack'
%% drop_catch(CatchTag, Stack) -> Stack'
%% Special interface for putting and removing catch tags, to ensure that
%% catches nest properly. Also used for try tags.
put_catch(Tag, Stk0) -> put_catch(Tag, reverse(Stk0), []).
put_catch(Tag, [], Stk) ->
put_stack({catch_tag,Tag}, Stk);
put_catch(Tag, [{{catch_tag,_}}|_]=RevStk, Stk) ->
reverse(RevStk, put_stack({catch_tag,Tag}, Stk));
put_catch(Tag, [Other|Stk], Acc) ->
put_catch(Tag, Stk, [Other|Acc]).
drop_catch(Tag, [{{catch_tag,Tag}}|Stk]) -> [free|Stk];
drop_catch(Tag, [Other|Stk]) -> [Other|drop_catch(Tag, Stk)].
%% new_label(St) -> {L,St}.
new_label(#cg{lcount=Next}=St) ->
{Next,St#cg{lcount=Next+1}}.
flatmapfoldl(F, Accu0, [Hd|Tail]) ->
{R,Accu1} = F(Hd, Accu0),
{Rs,Accu2} = flatmapfoldl(F, Accu1, Tail),
{R++Rs,Accu2};
flatmapfoldl(_, Accu, []) -> {[],Accu}.
