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ragge
1.45
1 /*      $Id: optim.c,v 1.45 2011/08/03 19:21:05 ragge Exp $     */
ragge
1.10
2 /*
3  * Copyright(C) Caldera International Inc. 2001-2002. All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * Redistributions of source code and documentation must retain the above
10  * copyright notice, this list of conditions and the following disclaimer.
11  * Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditionsand the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  * All advertising materials mentioning features or use of this software
15  * must display the following acknowledgement:
16  *      This product includes software developed or owned by Caldera
17  *      International, Inc.
18  * Neither the name of Caldera International, Inc. nor the names of other
19  * contributors may be used to endorse or promote products derived from
20  * this software without specific prior written permission.
21  *
22  * USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
23  * INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
25  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
26  * DISCLAIMED.  IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE
27  * FOR ANY DIRECT, INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OFLIABILITY, WHETHER IN CONTRACT,
31  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
32  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
33  * POSSIBILITY OF SUCH DAMAGE.
34  */
ragge
1.1
35
36 # include "pass1.h"
37
38 # define SWAP(p,q) {sp=p; p=q; q=sp;}
ragge
1.3
39 # define RCON(p) (p->n_right->n_op==ICON)
40 # define RO(p) p->n_right->n_op
41 # define RV(p) p->n_right->n_lval
42 # define LCON(p) (p->n_left->n_op==ICON)
43 # define LO(p) p->n_left->n_op
44 # define LV(p) p->n_left->n_lval
ragge
1.1
45
ragge
1.21
46 /* remove left node */
47 static NODE *
48 zapleft(NODE *p)
49 {
50         NODE *q;
51
52         q = p->n_left;
53         nfree(p->n_right);
54         nfree(p);
55         return q;
56 }
57
ragge
1.2
58 /*
59  * fortran function arguments
60  */
ragge
1.9
61 static NODE *
ragge
1.2
62 fortarg(NODE *p)
63 {
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1.3
64         ifp->n_op == CM ){
65                 p->n_left = fortargp->n_left );
66                 p->n_right = fortargp->n_right );
ragge
1.1
67                 return(p);
ragge
1.2
68         }
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1.1
69
ragge
1.3
70         whileISPTR(p->n_type) ){
ragge
1.16
71                 p = buildtreeUMULpNIL );
ragge
1.2
72         }
ragge
1.1
73         returnoptim(p) );
ragge
1.2
74 }
ragge
1.1
75
76         /* mapping relationals when the sides are reversed */
77 short revrel[] ={ EQNEGEGTLELTUGEUGTULEULT };
ragge
1.2
78
79 /*
80  * local optimizations, most of which are probably
81  * machine independent
82  */
ragge
1.1
83 NODE *
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1.2
84 optim(NODE *p)
85 {
86         int oty;
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1.8
87         NODE *sp, *q;
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1.38
88         int isz;
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1.1
89
90         ifoflag ) return(p);
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1.21
91
ragge
1.44
92
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1.21
93         ty = coptype(p->n_op);
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1.1
94         ifty == LTYPE ) return(p);
95
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1.3
96         ifty == BITYPE ) p->n_right = optim(p->n_right);
97         p->n_left = optim(p->n_left);
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1.1
98
99         /* collect constants */
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1.21
100 again:  o = p->n_op;
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1.1
101         switch(o){
102
103         case SCONV:
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1.42
104                 if (concast(p->n_leftp->n_type)) {
105                         q = p->n_left;
106                         nfree(p);
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1.44
107                         p = q;
108                         break;
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1.42
109                 }
110                 /* FALLTHROUGH */
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1.1
111         case PCONV:
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1.44
112                 p = clocal(p);
113                 break;
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1.1
114
115         case FORTCALL:
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1.3
116                 p->n_right = fortargp->n_right );
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1.1
117                 break;
118
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1.15
119         case ADDROF:
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1.20
120                 if (LO(p) == TEMP)
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1.44
121                         break;
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1.10
122                 ifLO(p) != NAME ) cerror"& error" );
123
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1.44
124                 if( !andable(p->n_left) && !statinit)
125                         break;
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1.1
126
127                 LO(p) = ICON;
128
129                 setuleft:
130                 /* paint over the type of the left hand side with the type of the top */
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1.3
131                 p->n_left->n_type = p->n_type;
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1.7
132                 p->n_left->n_df = p->n_df;
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1.35
133                 p->n_left->n_ap = p->n_ap;
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1.8
134                 q = p->n_left;
135                 nfree(p);
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1.44
136                 p = q;
137                 break;
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1.1
138
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1.45
139         case NOT:
140         case UMINUS:
141         case COMPL:
142                 if (LCON(p) && conval(p->n_leftop->n_left))
143                         p = nfree(p);
144                 break;
145
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1.16
146         case UMUL:
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1.36
147                 if (LO(p) == ADDROF) {
148                         q = p->n_left->n_left;
149                         nfree(p->n_left);
150                         nfree(p);
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1.44
151                         p = q;
152                         break;
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1.36
153                 }
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1.1
154                 ifLO(p) != ICON ) break;
155                 LO(p) = NAME;
156                 goto setuleft;
157
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1.21
158         case RS:
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1.37
159                 if (LCON(p) && RCON(p) && conval(p->n_leftop->n_right))
160                         goto zapright;
161
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1.38
162                 sz = tsize(p->n_typep->n_dfp->n_ap);
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1.34
163
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1.31
164                 if (LO(p) == RS && RCON(p->n_left) && RCON(p) &&
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1.38
165                     (RV(p) + RV(p->n_left)) < sz) {
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1.21
166                         /* two right-shift  by constants */
167                         RV(p) += RV(p->n_left);
168                         p->n_left = zapleft(p->n_left);
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1.23
169                 }
170 #if 0
171                   else if (LO(p) == LS && RCON(p->n_left) && RCON(p)) {
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1.21
172                         RV(p) -= RV(p->n_left);
173                         if (RV(p) < 0)
174                                 o = p->n_op = LSRV(p) = -RV(p);
175                         p->n_left = zapleft(p->n_left);
176                 }
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1.23
177 #endif
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1.22
178                 if (RO(p) == ICON) {
179                         if (RV(p) < 0) {
180                                 RV(p) = -RV(p);
181                                 p->n_op = LS;
182                                 goto again;
183                         }
ragge
1.24
184 #ifdef notyet /* must check for side effects, --a >> 32; */
ragge
1.22
185                         if (RV(p) >= tsize(p->n_typep->n_dfp->n_sue) &&
186                             ISUNSIGNED(p->n_type)) { /* ignore signed shifts */
187                                 /* too many shifts */
188                                 tfree(p->n_left);
189                                 nfree(p->n_right);
190                                 p->n_op = ICONp->n_lval = 0p->n_sp = NULL;
ragge
1.24
191                         } else
192 #endif
ragge
1.26
193                         /* avoid larger shifts than type size */
ragge
1.38
194                         if (RV(p) >= sz) {
195                                 RV(p) = RV(p) % sz;
ragge
1.26
196                                 werror("shift larger than type");
197                         }
ragge
1.24
198                         if (RV(p) == 0)
ragge
1.22
199                                 p = zapleft(p);
ragge
1.21
200                 }
201                 break;
202
203         case LS:
ragge
1.37
204                 if (LCON(p) && RCON(p) && conval(p->n_leftop->n_right))
205                         goto zapright;
206
ragge
1.38
207                 sz = tsize(p->n_typep->n_dfp->n_ap);
ragge
1.34
208
ragge
1.21
209                 if (LO(p) == LS && RCON(p->n_left) && RCON(p)) {
210                         /* two left-shift  by constants */
211                         RV(p) += RV(p->n_left);
212                         p->n_left = zapleft(p->n_left);
ragge
1.23
213                 }
214 #if 0
215                   else if (LO(p) == RS && RCON(p->n_left) && RCON(p)) {
ragge
1.21
216                         RV(p) -= RV(p->n_left);
217                         p->n_left = zapleft(p->n_left);
218                 }
ragge
1.23
219 #endif
ragge
1.22
220                 if (RO(p) == ICON) {
221                         if (RV(p) < 0) {
222                                 RV(p) = -RV(p);
223                                 p->n_op = RS;
224                                 goto again;
225                         }
ragge
1.24
226 #ifdef notyet /* must check for side effects */
ragge
1.22
227                         if (RV(p) >= tsize(p->n_typep->n_dfp->n_sue)) {
228                                 /* too many shifts */
229                                 tfree(p->n_left);
230                                 nfree(p->n_right);
231                                 p->n_op = ICONp->n_lval = 0p->n_sp = NULL;
ragge
1.24
232                         } else
233 #endif
ragge
1.26
234                         /* avoid larger shifts than type size */
ragge
1.38
235                         if (RV(p) >= sz) {
236                                 RV(p) = RV(p) % sz;
ragge
1.26
237                                 werror("shift larger than type");
238                         }
ragge
1.24
239                         if (RV(p) == 0)  
ragge
1.22
240                                 p = zapleft(p);
ragge
1.21
241                 }
242                 break;
243
ragge
1.1
244         case MINUS:
ragge
1.19
245                 if (LCON(p) && RCON(p) && p->n_left->n_sp == p->n_right->n_sp) {
246                         /* link-time constants, but both are the same */
247                         /* solve it now by forgetting the symbols */
248                         p->n_left->n_sp = p->n_right->n_sp = NULL;
249                 }
ragge
1.3
250                 if( !nncon(p->n_right) ) break;
ragge
1.1
251                 RV(p) = -RV(p);
ragge
1.3
252                 o = p->n_op = PLUS;
ragge
1.1
253
254         case MUL:
ragge
1.43
255                 /*
256                  * Check for u=(x-y)+z; where all vars are pointers to
257                  * the same struct. This has two advantages:
258                  * 1: avoid a mul+div
259                  * 2: even if not allowed, people may get surprised if this
260                  *    calculation do not give correct result if using
261                  *    unaligned structs.
262                  */
263                 if (p->n_type == INTPTR && RCON(p) &&
264                     LO(p) == DIV && RCON(p->n_left) &&
265                     RV(p) == RV(p->n_left) &&
266                     LO(p->n_left) == MINUS) {
267                         q = p->n_left->n_left;
268                         if (q->n_left->n_type == PTR+STRTY &&
269                             q->n_right->n_type == PTR+STRTY &&
270                             strmemb(q->n_left->n_ap) ==
271                             strmemb(q->n_right->n_ap)) {
272                                 p = zapleft(p);
273                                 p = zapleft(p);
274                         }
275                 }
276                 /* FALLTHROUGH */
ragge
1.1
277         case PLUS:
278         case AND:
279         case OR:
280         case ER:
281                 /* commutative ops; for now, just collect constants */
282                 /* someday, do it right */
ragge
1.14
283                 ifnncon(p->n_left) || ( LCON(p) && !RCON(p) ) )
284                         SWAPp->n_leftp->n_right );
ragge
1.1
285                 /* make ops tower to the left, not the right */
286                 ifRO(p) == o ){
287                         NODE *t1, *t2, *t3;
ragge
1.3
288                         t1 = p->n_left;
289                         sp = p->n_right;
290                         t2 = sp->n_left;
291                         t3 = sp->n_right;
ragge
1.1
292                         /* now, put together again */
ragge
1.3
293                         p->n_left = sp;
294                         sp->n_left = t1;
295                         sp->n_right = t2;
ragge
1.45
296                         sp->n_type = p->n_type;
ragge
1.3
297                         p->n_right = t3;
ragge
1.1
298                         }
ragge
1.3
299                 if(o == PLUS && LO(p) == MINUS && RCON(p) && RCON(p->n_left) &&
300                    conval(p->n_rightMINUSp->n_left->n_right)){
ragge
1.1
301                         zapleft:
ragge
1.8
302
303                         q = p->n_left->n_left;
304                         nfree(p->n_left->n_right);
305                         nfree(p->n_left);
306                         p->n_left = q;
ragge
1.1
307                 }
ragge
1.14
308                 ifRCON(p) && LO(p)==o && RCON(p->n_left) &&
309                     convalp->n_rightop->n_left->n_right ) ){
ragge
1.1
310                         goto zapleft;
311                         }
ragge
1.10
312                 else ifLCON(p) && RCON(p) && convalp->n_leftop->n_right ) ){
ragge
1.1
313                         zapright:
ragge
1.8
314                         nfree(p->n_right);
ragge
1.14
315                         q = makety(p->n_leftp->n_typep->n_qual,
ragge
1.35
316                             p->n_dfp->n_ap);
ragge
1.8
317                         nfree(p);
ragge
1.44
318                         p = clocal(q);
319                         break;
ragge
1.10
320                         }
ragge
1.1
321
ragge
1.10
322                 /* change muls to shifts */
ragge
1.1
323
ragge
1.10
324                 ifo == MUL && nncon(p->n_right) && (i=ispow2(RV(p)))>=0){
325                         ifi == 0 ) { /* multiplication by 1 */
ragge
1.1
326                                 goto zapright;
327                                 }
ragge
1.10
328                         o = p->n_op = LS;
329                         p->n_right->n_type = INT;
330                         p->n_right->n_df = NULL;
331                         RV(p) = i;
ragge
1.1
332                         }
333
334                 /* change +'s of negative consts back to - */
ragge
1.3
335                 ifo==PLUS && nncon(p->n_right) && RV(p)<0 ){
ragge
1.1
336                         RV(p) = -RV(p);
ragge
1.3
337                         o = p->n_op = MINUS;
ragge
1.1
338                         }
ragge
1.28
339
340                 /* remove ops with RHS 0 */
341                 if ((o == PLUS || o == MINUS || o == OR || o == ER) &&
342                     nncon(p->n_right) && RV(p) == 0) {
343                         goto zapright;
344                 }
ragge
1.1
345                 break;
346
347         case DIV:
ragge
1.19
348                 ifnnconp->n_right ) && p->n_right->n_lval == 1 )
349                         goto zapright;
350                 if (LCON(p) && RCON(p) && conval(p->n_leftDIVp->n_right))
351                         goto zapright;
ragge
1.25
352                 if (RCON(p) && ISUNSIGNED(p->n_type) && (i=ispow2(RV(p))) > 0) {
353                         p->n_op = RS;
354                         RV(p) = i;
ragge
1.27
355                         q = p->n_right;
ragge
1.35
356                         if(tsize(q->n_typeq->n_dfq->n_ap) > SZINT)
ragge
1.38
357                                 p->n_right = makety(qINT000);
ragge
1.27
358
ragge
1.25
359                         break;
360                 }
361                 break;
362
363         case MOD:
364                 if (RCON(p) && ISUNSIGNED(p->n_type) && ispow2(RV(p)) > 0) {
365                         p->n_op = AND;
366                         RV(p) = RV(p) -1;
367                         break;
368                 }
ragge
1.1
369                 break;
370
371         case EQ:
372         case NE:
373         case LT:
374         case LE:
375         case GT:
376         case GE:
377         case ULT:
378         case ULE:
379         case UGT:
380         case UGE:
381                 if( !LCON(p) ) break;
382
383                 /* exchange operands */
384
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1.3
385                 sp = p->n_left;
386                 p->n_left = p->n_right;
387                 p->n_right = sp;
388                 p->n_op = revrel[p->n_op - EQ ];
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1.1
389                 break;
390
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1.32
391 #ifdef notyet
392         case ASSIGN:
393                 /* Simple test to avoid two branches */
394                 if (RO(p) != NE)
395                         break;
396                 q = p->n_right;
397                 if (RCON(q) && RV(q) == 0 && LO(q) == AND &&
398                     RCON(q->n_left) && (i = ispow2(RV(q->n_left))) &&
399                     q->n_left->n_type == INT) {
400                         q->n_op = RS;
401                         RV(q) = i;
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1.1
402                 }
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1.32
403                 break;
404 #endif
405         }
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1.1
406
407         return(p);
408         }
409
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1.2
410 int
411 ispow2(CONSZ c)
412 {
413         int i;
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1.1
414         ifc <= 0 || (c&(c-1)) ) return(-1);
415         fori=0c>1; ++ic >>= 1;
416         return(i);
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1.2
417 }
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1.10
418
419 int
420 nnconp ) NODE *p; {
421         /* is p a constant without a name */
422         returnp->n_op == ICON && p->n_sp == NULL );
423         }
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Atlassian FishEye, CVS analysis. (Version:1.6.3 Build:build-336 2008-11-04) - Administration - Page generated 2014-09-01 20:38 +0200