aboutsummaryrefslogtreecommitdiffstats
path: root/lib/compiler/src/beam_except.erl
blob: d261809765a31b0cdae2f24769d31b3e89536551 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2011-2013. 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%
%%

-module(beam_except).
-export([module/2]).

%%% Rewrite certain calls to erlang:error/{1,2} to specialized
%%% instructions:
%%%
%%% erlang:error({badmatch,Value})       => badmatch Value
%%% erlang:error({case_clause,Value})    => case_end Value
%%% erlang:error({try_clause,Value})     => try_case_end Value
%%% erlang:error(if_clause)              => if_end
%%% erlang:error(function_clause, Args)  => jump FuncInfoLabel
%%%

-import(lists, [reverse/1]).

module({Mod,Exp,Attr,Fs0,Lc}, _Opt) ->
    Fs = [function(F) || F <- Fs0],
    {ok,{Mod,Exp,Attr,Fs,Lc}}.

function({function,Name,Arity,CLabel,Is0}) ->
    try
	Is = function_1(Is0),
	{function,Name,Arity,CLabel,Is}
    catch
	Class:Error ->
	    Stack = erlang:get_stacktrace(),
	    io:fwrite("Function: ~w/~w\n", [Name,Arity]),
	    erlang:raise(Class, Error, Stack)
    end.

-record(st,
	{lbl,					%func_info label
	 loc,					%location for func_info
	 arity					%arity for function
	 }).

function_1(Is0) ->
    case Is0 of
	[{label,Lbl},{line,Loc},{func_info,_,_,Arity}|_] ->
	    St = #st{lbl=Lbl,loc=Loc,arity=Arity},
	    translate(Is0, St, []);
	[{label,_}|_] ->
	    %% No line numbers. The source must be a .S file.
	    %% There is no need to do anything.
	    Is0
    end.

translate([{call_ext,Ar,{extfunc,erlang,error,Ar}}=I|Is], St, Acc) ->
    translate_1(Ar, I, Is, St, Acc);
translate([I|Is], St, Acc) ->
    translate(Is, St, [I|Acc]);
translate([], _, Acc) ->
    reverse(Acc).

translate_1(Ar, I, Is, St, [{line,_}=Line|Acc1]=Acc0) ->
    case dig_out(Ar, Acc1) of
	no ->
	    translate(Is, St, [I|Acc0]);
	{yes,{function_clause,Arity},Acc2} ->
	    case {Line,St} of
		{{line,Loc},#st{lbl=Fi,loc=Loc,arity=Arity}} ->
		    Instr = {jump,{f,Fi}},
		    translate(Is, St, [Instr|Acc2]);
		{_,_} ->
		    %% This must be "error(function_clause, Args)" in
		    %% the Erlang source code or a fun. Don't translate.
		    translate(Is, St, [I|Acc0])
	    end;
	{yes,Instr,Acc2} ->
	    translate(Is, St, [Instr,Line|Acc2])
    end.

dig_out(Ar, [{kill,_}|Is]) ->
    dig_out(Ar, Is);
dig_out(1, [{block,Bl0}|Is]) ->
    case dig_out_block(reverse(Bl0)) of
	no -> no;
	{yes,What,[]} ->
	    {yes,What,Is};
	{yes,What,Bl} ->
	    {yes,What,[{block,Bl}|Is]}
    end;
dig_out(2, [{block,Bl}|Is]) ->
    case dig_out_block_fc(Bl) of
	no -> no;
	{yes,What} -> {yes,What,Is}
    end;
dig_out(_, _) -> no.

dig_out_block([{set,[{x,0}],[{atom,if_clause}],move}]) ->
    {yes,if_end,[]};
dig_out_block([{set,[{x,0}],[{literal,{Exc,Value}}],move}|Is]) ->
    translate_exception(Exc, {literal,Value}, Is, 0);
dig_out_block([{set,[{x,0}],[Tuple],move},
	       {set,[],[Value],put},
	       {set,[],[{atom,Exc}],put},
	       {set,[Tuple],[],{put_tuple,2}}|Is]) ->
    translate_exception(Exc, Value, Is, 3);
dig_out_block([{set,[],[Value],put},
	       {set,[],[{atom,Exc}],put},
	       {set,[{x,0}],[],{put_tuple,2}}|Is]) ->
    translate_exception(Exc, Value, Is, 3);
dig_out_block(_) -> no.

translate_exception(badmatch, Val, Is, Words) ->
    {yes,{badmatch,Val},fix_block(Is, Words)};
translate_exception(case_clause, Val, Is, Words) ->
    {yes,{case_end,Val},fix_block(Is, Words)};
translate_exception(try_clause, Val, Is, Words) ->
    {yes,{try_case_end,Val},fix_block(Is, Words)};
translate_exception(_, _, _, _) -> no.

fix_block(Is, 0) ->
    reverse(Is);
fix_block(Is, Words) ->
    fix_block_1(reverse(Is), Words).

fix_block_1([{set,[],[],{alloc,Live,{F1,F2,Needed,F3}}}|Is], Words) ->
    [{set,[],[],{alloc,Live,{F1,F2,Needed-Words,F3}}}|Is];
fix_block_1([I|Is], Words) ->
    [I|fix_block_1(Is, Words)].

dig_out_block_fc([{set,[],[],{alloc,Live,_}}|Bl]) ->
    case dig_out_fc(Bl, Live-1, nil) of
	no ->
	    no;
	yes ->
	    {yes,{function_clause,Live}}
    end;
dig_out_block_fc(_) -> no.

dig_out_fc([{set,[Dst],[{x,Reg},Dst0],put_list}|Is], Reg, Dst0) ->
    dig_out_fc(Is, Reg-1, Dst);
dig_out_fc([{set,[{x,0}],[{atom,function_clause}],move}], -1, {x,1}) ->
    yes;
dig_out_fc(_, _, _) -> no.