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1 | # Stackobj.pm |
2 | # |
3 | # Copyright (c) 1996 Malcolm Beattie |
4 | # |
5 | # You may distribute under the terms of either the GNU General Public |
6 | # License or the Artistic License, as specified in the README file. |
7 | # |
8 | package B::Stackobj; |
9 | use Exporter (); |
10 | @ISA = qw(Exporter); |
11 | @EXPORT_OK = qw(set_callback T_UNKNOWN T_DOUBLE T_INT |
12 | VALID_INT VALID_DOUBLE VALID_SV REGISTER TEMPORARY); |
13 | %EXPORT_TAGS = (types => [qw(T_UNKNOWN T_DOUBLE T_INT)], |
14 | flags => [qw(VALID_INT VALID_DOUBLE VALID_SV |
15 | REGISTER TEMPORARY)]); |
16 | |
17 | use Carp qw(confess); |
18 | use strict; |
19 | use B qw(class); |
20 | |
21 | # Perl internal constants that I should probably define elsewhere. |
22 | sub SVf_IOK () { 0x10000 } |
23 | sub SVf_NOK () { 0x20000 } |
24 | |
25 | # Types |
26 | sub T_UNKNOWN () { 0 } |
27 | sub T_DOUBLE () { 1 } |
28 | sub T_INT () { 2 } |
29 | |
30 | # Flags |
31 | sub VALID_INT () { 0x01 } |
32 | sub VALID_DOUBLE () { 0x02 } |
33 | sub VALID_SV () { 0x04 } |
34 | sub REGISTER () { 0x08 } # no implicit write-back when calling subs |
35 | sub TEMPORARY () { 0x10 } # no implicit write-back needed at all |
36 | |
37 | # |
38 | # Callback for runtime code generation |
39 | # |
40 | my $runtime_callback = sub { confess "set_callback not yet called" }; |
41 | sub set_callback (&) { $runtime_callback = shift } |
42 | sub runtime { &$runtime_callback(@_) } |
43 | |
44 | # |
45 | # Methods |
46 | # |
47 | |
48 | sub write_back { confess "stack object does not implement write_back" } |
49 | |
50 | sub invalidate { shift->{flags} &= ~(VALID_INT | VALID_DOUBLE) } |
51 | |
52 | sub as_sv { |
53 | my $obj = shift; |
54 | if (!($obj->{flags} & VALID_SV)) { |
55 | $obj->write_back; |
56 | $obj->{flags} |= VALID_SV; |
57 | } |
58 | return $obj->{sv}; |
59 | } |
60 | |
61 | sub as_int { |
62 | my $obj = shift; |
63 | if (!($obj->{flags} & VALID_INT)) { |
64 | $obj->load_int; |
65 | $obj->{flags} |= VALID_INT; |
66 | } |
67 | return $obj->{iv}; |
68 | } |
69 | |
70 | sub as_double { |
71 | my $obj = shift; |
72 | if (!($obj->{flags} & VALID_DOUBLE)) { |
73 | $obj->load_double; |
74 | $obj->{flags} |= VALID_DOUBLE; |
75 | } |
76 | return $obj->{nv}; |
77 | } |
78 | |
79 | sub as_numeric { |
80 | my $obj = shift; |
81 | return $obj->{type} == T_INT ? $obj->as_int : $obj->as_double; |
82 | } |
83 | |
84 | # |
85 | # Debugging methods |
86 | # |
87 | sub peek { |
88 | my $obj = shift; |
89 | my $type = $obj->{type}; |
90 | my $flags = $obj->{flags}; |
91 | my @flags; |
92 | if ($type == T_UNKNOWN) { |
93 | $type = "T_UNKNOWN"; |
94 | } elsif ($type == T_INT) { |
95 | $type = "T_INT"; |
96 | } elsif ($type == T_DOUBLE) { |
97 | $type = "T_DOUBLE"; |
98 | } else { |
99 | $type = "(illegal type $type)"; |
100 | } |
101 | push(@flags, "VALID_INT") if $flags & VALID_INT; |
102 | push(@flags, "VALID_DOUBLE") if $flags & VALID_DOUBLE; |
103 | push(@flags, "VALID_SV") if $flags & VALID_SV; |
104 | push(@flags, "REGISTER") if $flags & REGISTER; |
105 | push(@flags, "TEMPORARY") if $flags & TEMPORARY; |
106 | @flags = ("none") unless @flags; |
107 | return sprintf("%s type=$type flags=%s sv=$obj->{sv}", |
108 | class($obj), join("|", @flags)); |
109 | } |
110 | |
111 | sub minipeek { |
112 | my $obj = shift; |
113 | my $type = $obj->{type}; |
114 | my $flags = $obj->{flags}; |
115 | if ($type == T_INT || $flags & VALID_INT) { |
116 | return $obj->{iv}; |
117 | } elsif ($type == T_DOUBLE || $flags & VALID_DOUBLE) { |
118 | return $obj->{nv}; |
119 | } else { |
120 | return $obj->{sv}; |
121 | } |
122 | } |
123 | |
124 | # |
125 | # Caller needs to ensure that set_int, set_double, |
126 | # set_numeric and set_sv are only invoked on legal lvalues. |
127 | # |
128 | sub set_int { |
129 | my ($obj, $expr) = @_; |
130 | runtime("$obj->{iv} = $expr;"); |
131 | $obj->{flags} &= ~(VALID_SV | VALID_DOUBLE); |
132 | $obj->{flags} |= VALID_INT; |
133 | } |
134 | |
135 | sub set_double { |
136 | my ($obj, $expr) = @_; |
137 | runtime("$obj->{nv} = $expr;"); |
138 | $obj->{flags} &= ~(VALID_SV | VALID_INT); |
139 | $obj->{flags} |= VALID_DOUBLE; |
140 | } |
141 | |
142 | sub set_numeric { |
143 | my ($obj, $expr) = @_; |
144 | if ($obj->{type} == T_INT) { |
145 | $obj->set_int($expr); |
146 | } else { |
147 | $obj->set_double($expr); |
148 | } |
149 | } |
150 | |
151 | sub set_sv { |
152 | my ($obj, $expr) = @_; |
153 | runtime("SvSetSV($obj->{sv}, $expr);"); |
154 | $obj->invalidate; |
155 | $obj->{flags} |= VALID_SV; |
156 | } |
157 | |
158 | # |
159 | # Stackobj::Padsv |
160 | # |
161 | |
162 | @B::Stackobj::Padsv::ISA = 'B::Stackobj'; |
163 | sub B::Stackobj::Padsv::new { |
164 | my ($class, $type, $extra_flags, $ix, $iname, $dname) = @_; |
165 | bless { |
166 | type => $type, |
167 | flags => VALID_SV | $extra_flags, |
81009501 |
168 | sv => "PL_curpad[$ix]", |
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169 | iv => "$iname", |
170 | nv => "$dname" |
171 | }, $class; |
172 | } |
173 | |
174 | sub B::Stackobj::Padsv::load_int { |
175 | my $obj = shift; |
176 | if ($obj->{flags} & VALID_DOUBLE) { |
177 | runtime("$obj->{iv} = $obj->{nv};"); |
178 | } else { |
179 | runtime("$obj->{iv} = SvIV($obj->{sv});"); |
180 | } |
181 | $obj->{flags} |= VALID_INT; |
182 | } |
183 | |
184 | sub B::Stackobj::Padsv::load_double { |
185 | my $obj = shift; |
186 | $obj->write_back; |
187 | runtime("$obj->{nv} = SvNV($obj->{sv});"); |
188 | $obj->{flags} |= VALID_DOUBLE; |
189 | } |
190 | |
191 | sub B::Stackobj::Padsv::write_back { |
192 | my $obj = shift; |
193 | my $flags = $obj->{flags}; |
194 | return if $flags & VALID_SV; |
195 | if ($flags & VALID_INT) { |
196 | runtime("sv_setiv($obj->{sv}, $obj->{iv});"); |
197 | } elsif ($flags & VALID_DOUBLE) { |
198 | runtime("sv_setnv($obj->{sv}, $obj->{nv});"); |
199 | } else { |
200 | confess "write_back failed for lexical @{[$obj->peek]}\n"; |
201 | } |
202 | $obj->{flags} |= VALID_SV; |
203 | } |
204 | |
205 | # |
206 | # Stackobj::Const |
207 | # |
208 | |
209 | @B::Stackobj::Const::ISA = 'B::Stackobj'; |
210 | sub B::Stackobj::Const::new { |
211 | my ($class, $sv) = @_; |
212 | my $obj = bless { |
213 | flags => 0, |
214 | sv => $sv # holds the SV object until write_back happens |
215 | }, $class; |
216 | my $svflags = $sv->FLAGS; |
217 | if ($svflags & SVf_IOK) { |
218 | $obj->{flags} = VALID_INT|VALID_DOUBLE; |
219 | $obj->{type} = T_INT; |
220 | $obj->{nv} = $obj->{iv} = $sv->IV; |
221 | } elsif ($svflags & SVf_NOK) { |
222 | $obj->{flags} = VALID_INT|VALID_DOUBLE; |
223 | $obj->{type} = T_DOUBLE; |
224 | $obj->{iv} = $obj->{nv} = $sv->NV; |
225 | } else { |
226 | $obj->{type} = T_UNKNOWN; |
227 | } |
228 | return $obj; |
229 | } |
230 | |
231 | sub B::Stackobj::Const::write_back { |
232 | my $obj = shift; |
233 | return if $obj->{flags} & VALID_SV; |
234 | # Save the SV object and replace $obj->{sv} by its C source code name |
235 | $obj->{sv} = $obj->{sv}->save; |
236 | $obj->{flags} |= VALID_SV|VALID_INT|VALID_DOUBLE; |
237 | } |
238 | |
239 | sub B::Stackobj::Const::load_int { |
240 | my $obj = shift; |
241 | $obj->{iv} = int($obj->{sv}->PV); |
242 | $obj->{flags} |= VALID_INT; |
243 | } |
244 | |
245 | sub B::Stackobj::Const::load_double { |
246 | my $obj = shift; |
247 | $obj->{nv} = $obj->{sv}->PV + 0.0; |
248 | $obj->{flags} |= VALID_DOUBLE; |
249 | } |
250 | |
251 | sub B::Stackobj::Const::invalidate {} |
252 | |
253 | # |
254 | # Stackobj::Bool |
255 | # |
256 | |
257 | @B::Stackobj::Bool::ISA = 'B::Stackobj'; |
258 | sub B::Stackobj::Bool::new { |
259 | my ($class, $preg) = @_; |
260 | my $obj = bless { |
261 | type => T_INT, |
262 | flags => VALID_INT|VALID_DOUBLE, |
263 | iv => $$preg, |
264 | nv => $$preg, |
265 | preg => $preg # this holds our ref to the pseudo-reg |
266 | }, $class; |
267 | return $obj; |
268 | } |
269 | |
270 | sub B::Stackobj::Bool::write_back { |
271 | my $obj = shift; |
272 | return if $obj->{flags} & VALID_SV; |
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273 | $obj->{sv} = "($obj->{iv} ? &PL_sv_yes : &PL_sv_no)"; |
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274 | $obj->{flags} |= VALID_SV; |
275 | } |
276 | |
277 | # XXX Might want to handle as_double/set_double/load_double? |
278 | |
279 | sub B::Stackobj::Bool::invalidate {} |
280 | |
281 | 1; |
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282 | |
283 | __END__ |
284 | |
285 | =head1 NAME |
286 | |
287 | B::Stackobj - Helper module for CC backend |
288 | |
289 | =head1 SYNOPSIS |
290 | |
291 | use B::Stackobj; |
292 | |
293 | =head1 DESCRIPTION |
294 | |
295 | See F<ext/B/README>. |
296 | |
297 | =head1 AUTHOR |
298 | |
299 | Malcolm Beattie, C<mbeattie@sable.ox.ac.uk> |
300 | |
301 | =cut |