Home
stmt.c - scc - simple c99 compiler
HTML git clone git://git.simple-cc.org/scc
DIR Log
DIR Files
DIR Refs
DIR Submodules
DIR README
DIR LICENSE
---
stmt.c (7065B)
---
1 #include <stddef.h>
2 #include <setjmp.h>
3
4 #include <scc/cstd.h>
5 #include <scc/scc.h>
6 #include "cc1.h"
7
8 #define NEGATE 1
9 #define NONEGATE 0
10
11 Symbol *curfun;
12
13 static void stmt(Symbol *lbreak, Symbol *lcont, Switch *lswitch);
14
15 static void
16 label(void)
17 {
18 Symbol *sym;
19
20 switch (yytoken) {
21 case IDEN:
22 case TYPEIDEN:
23 sym = lookup(NS_LABEL, yytext, ALLOC);
24 if (sym->flags & SDEFINED)
25 error("label '%s' already defined", yytext);
26 if ((sym->flags & SDECLARED) == 0)
27 sym = install(NS_LABEL, sym);
28 sym->flags |= SDEFINED;
29 emit(OLABEL, sym);
30 next();
31 expect(':');
32 break;
33 default:
34 unexpected();
35 }
36 }
37
38 static void
39 stmtexp(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
40 {
41 Node *np;
42
43 if (accept(';'))
44 return;
45 if (yytoken == IDEN && ahead() == ':') {
46 label();
47 stmt(lbreak, lcont, lswitch);
48 return;
49 }
50 np = simplify(expr());
51 if ((np->flags & NEFFECT) == 0)
52 warn("expression without side effects");
53 emit(OEXPR, np);
54 expect(';');
55 }
56
57 static Node *
58 condition(int neg)
59 {
60 Node *np;
61
62 expect('(');
63 np = condexpr(neg);
64 expect(')');
65
66 return np;
67 }
68
69 static void
70 While(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
71 {
72 Symbol *begin;
73 Node *np;
74
75 begin = newlabel();
76 lcont = newlabel();
77 lbreak = newlabel();
78
79 expect(WHILE);
80 np = condition(NONEGATE);
81
82 emit(OJUMP, lcont);
83
84 emit(OBLOOP, NULL);
85 emit(OLABEL, begin);
86 stmt(lbreak, lcont, lswitch);
87 emit(OLABEL, lcont);
88 emit(OBRANCH, begin);
89 emit(OEXPR, np);
90 emit(OELOOP, NULL);
91
92 emit(OLABEL, lbreak);
93 }
94
95 static void
96 For(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
97 {
98 Symbol *begin, *cond;
99 Node *econd, *einc;
100
101 begin = newlabel();
102 lcont = newlabel();
103 cond = newlabel();
104 lbreak = newlabel();
105
106 pushctx();
107
108 expect(FOR);
109 expect('(');
110 switch (yytoken) {
111 case TYPE:
112 case TYPEIDEN:
113 case TQUALIFIER:
114 case SCLASS:
115 decl();
116 break;
117 default:
118 emit(OEXPR, simplify(expr()));
119 case ';':
120 expect(';');
121 break;
122 }
123 econd = (yytoken != ';') ? condexpr(NONEGATE) : NULL;
124 expect(';');
125 einc = (yytoken != ')') ? simplify(expr()) : NULL;
126 expect(')');
127
128 emit(OJUMP, cond);
129
130 emit(OBLOOP, NULL);
131 emit(OLABEL, begin);
132 stmt(lbreak, lcont, lswitch);
133 emit(OLABEL, lcont);
134 emit(OEXPR, einc);
135 emit(OLABEL, cond);
136 emit((econd) ? OBRANCH : OJUMP, begin);
137 emit(OEXPR, econd);
138 emit(OELOOP, NULL);
139
140 emit(OLABEL, lbreak);
141
142 popctx();
143 }
144
145 static void
146 Dowhile(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
147 {
148 Symbol *begin;
149 Node *np;
150
151 begin = newlabel();
152 lcont = newlabel();
153 lbreak = newlabel();
154
155 expect(DO);
156
157 emit(OBLOOP, NULL);
158 emit(OLABEL, begin);
159
160 stmt(lbreak, lcont, lswitch);
161 expect(WHILE);
162 np = condition(NONEGATE);
163 expect(';');
164
165 emit(OLABEL, lcont);
166 emit(OBRANCH, begin);
167 emit(OEXPR, np);
168 emit(OELOOP, NULL);
169
170 emit(OLABEL, lbreak);
171 }
172
173 static void
174 Return(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
175 {
176 Node *np = NULL;
177 Type *tp = curfun->type->type;
178
179 expect(RETURN);
180 if (yytoken != ';')
181 np = simplify(decay(expr()));
182 expect(';');
183
184 if (!np && tp != voidtype)
185 warn("function returning non void returns no value");
186 else if (np && np->type != tp) {
187 if (tp == voidtype)
188 warn("function returning void returns a value");
189 else if ((np = convert(np, tp, 0)) == NULL)
190 errorp("incorrect type in return");
191 }
192
193 emit(ORET, NULL);
194 emit(OEXPR, np);
195 }
196
197 static void
198 Break(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
199 {
200 expect(BREAK);
201 if (!lbreak) {
202 errorp("break statement not within loop or switch");
203 } else {
204 emit(OJUMP, lbreak);
205 expect(';');
206 }
207 }
208
209 static void
210 Continue(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
211 {
212 expect(CONTINUE);
213 if (!lcont) {
214 errorp("continue statement not within loop");
215 } else {
216 emit(OJUMP, lcont);
217 expect(';');
218 }
219 }
220
221 static void
222 Goto(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
223 {
224 Symbol *sym;
225
226 namespace = NS_LABEL;
227 next();
228 namespace = NS_IDEN;
229
230 if (yytoken != IDEN)
231 unexpected();
232 sym = yylval.sym;
233 if ((sym->flags & SDECLARED) == 0)
234 sym = install(NS_LABEL, sym);
235 sym->flags |= SUSED;
236 emit(OJUMP, sym);
237 next();
238 expect(';');
239 }
240
241 static void
242 Swtch(Symbol *obr, Symbol *lcont, Switch *osw)
243 {
244 Switch sw = {0};
245 Node *cond;
246 Symbol *lbreak;
247
248 expect(SWITCH);
249
250 expect ('(');
251 cond = simplify(convert(expr(), inttype, 0));
252 if (cond == NULL) {
253 errorp("incorrect type in switch statement");
254 cond = constnode(zero);
255 }
256 expect (')');
257
258 lbreak = newlabel();
259 emit(OBSWITCH, NULL);
260 emit(OEXPR, cond);
261 stmt(lbreak, lcont, &sw);
262 emit(OESWITCH, lbreak);
263 emit(OLABEL, lbreak);
264 }
265
266 static void
267 Case(Symbol *lbreak, Symbol *lcont, Switch *sw)
268 {
269 Node *np;
270 Symbol *label;
271
272 expect(CASE);
273 if ((np = constexpr()) == NULL)
274 errorp("case label does not reduce to an integer constant");
275 if (!sw) {
276 errorp("case label not within a switch statement");
277 } else if (sw->nr >= 0 && ++sw->nr == NR_SWITCH) {
278 errorp("too many case labels for a switch statement");
279 sw->nr = -1;
280 }
281 expect(':');
282
283 label = newlabel();
284 emit(OCASE, label);
285 emit(OEXPR, np);
286 emit(OLABEL, label);
287 stmt(lbreak, lcont, sw);
288 }
289
290 static void
291 Default(Symbol *lbreak, Symbol *lcont, Switch *sw)
292 {
293 Symbol *label = newlabel();
294
295 if (sw->hasdef)
296 errorp("multiple default labels in one switch");
297 sw->hasdef = 1;
298 expect(DEFAULT);
299 expect(':');
300 emit(ODEFAULT, label);
301 emit(OLABEL, label);
302 stmt(lbreak, lcont, sw);
303 }
304
305 static void
306 If(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
307 {
308 Symbol *end, *lelse;
309 Node *np;
310
311 lelse = newlabel();
312 expect(IF);
313 np = condition(NEGATE);
314 emit(OBRANCH, lelse);
315 emit(OEXPR, np);
316 stmt(lbreak, lcont, lswitch);
317 if (accept(ELSE)) {
318 end = newlabel();
319 emit(OJUMP, end);
320 emit(OLABEL, lelse);
321 stmt(lbreak, lcont, lswitch);
322 emit(OLABEL, end);
323 } else {
324 emit(OLABEL, lelse);
325 }
326 }
327
328 static void
329 blockit(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
330 {
331 switch (yytoken) {
332 case TYPEIDEN:
333 if (ahead() == ':')
334 goto parse_stmt;
335 case TYPE:
336 case TQUALIFIER:
337 case SCLASS:
338 decl();
339 return;
340 default:
341 parse_stmt:
342 stmt(lbreak, lcont, lswitch);
343 }
344 }
345
346 void
347 compound(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
348 {
349 static int nested;
350
351 pushctx();
352 expect('{');
353
354 if (nested == NR_BLOCK)
355 error("too many nesting levels of compound statements");
356
357 ++nested;
358 for (;;) {
359 if (yytoken == '}')
360 break;
361 blockit(lbreak, lcont, lswitch);
362 }
363 --nested;
364
365 popctx();
366 expect('}');
367 }
368
369 static void
370 stmt(Symbol *lbreak, Symbol *lcont, Switch *lswitch)
371 {
372 switch (yytoken) {
373 case '{':
374 compound(lbreak, lcont, lswitch);
375 break;
376 case RETURN:
377 Return(lbreak, lcont, lswitch);
378 break;
379 case WHILE:
380 While(lbreak, lcont, lswitch);
381 break;
382 case FOR:
383 For(lbreak, lcont, lswitch);
384 break;
385 case DO:
386 Dowhile(lbreak, lcont, lswitch);
387 break;
388 case IF:
389 If(lbreak, lcont, lswitch);
390 break;
391 case BREAK:
392 Break(lbreak, lcont, lswitch);
393 break;
394 case CONTINUE:
395 Continue(lbreak, lcont, lswitch);
396 break;
397 case GOTO:
398 Goto(lbreak, lcont, lswitch);
399 break;
400 case SWITCH:
401 Swtch(lbreak, lcont, lswitch);
402 break;
403 case CASE:
404 Case(lbreak, lcont, lswitch);
405 break;
406 case DEFAULT:
407 Default(lbreak, lcont, lswitch);
408 break;
409 default:
410 stmtexp(lbreak, lcont, lswitch);
411 }
412 }