2 * Copyright (C) 1995-2007 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Optimizations regarding Confirm nodes.
23 * @author Michael Beck
35 #include "iropt_dbg.h"
36 #include "opt_confirms.h"
41 MIN_INCLUDED = 0x00, /**< [min, ... */
42 MAX_INCLUDED = 0x00, /**< ..., max] */
43 MIN_EXCLUDED = 0x01, /**< (min, ... */
44 MAX_EXCLUDED = 0x02 /**< ..., max) */
48 * An interval. We could use
49 * intervals that ALWAYS include its borders, even for
50 * floating point, as the precision is limited.
51 * However, as our tarval module did not support
52 * such kind of operation, we use border flags allowing
55 typedef struct _interval_t {
56 tarval *min; /**< lowest border */
57 tarval *max; /**< highest border */
58 unsigned char flags; /**< border flags */
63 #define compare_iv(l_iv, r_iv, pnc) compare_iv_dbg(l_iv, r_iv, pnc)
66 static tarval *compare_iv_dbg(const interval_t *l_iv, const interval_t *r_iv, pn_Cmp pnc);
69 #define DBG_OUT_TR(l_pnc, l_bound, r_pnc, r_bound, pnc, v) \
70 ir_printf("In %e:\na %= %n && b %= %n ==> a %= b == %s\n", \
71 get_irg_entity(current_ir_graph), \
72 l_pnc, l_bound, r_pnc, r_bound, pnc, v);
75 #define DBG_OUT_R(r_pnc, r_bound, left, pnc, right, v) \
76 ir_printf("In %e:\na %= %n ==> %n %= %n == %s\n", \
77 get_irg_entity(current_ir_graph), \
78 r_pnc, r_bound, left, pnc, right, v);
81 #define DBG_OUT_L(l_pnc, l_bound, left, pnc, right, v) \
82 ir_printf("In %e:\na %= %n ==> %n %= %n == %s\n", \
83 get_irg_entity(current_ir_graph), \
84 l_pnc, l_bound, left, pnc, right, v);
88 #define DBG_OUT_TR(l_pnc, l_bound, r_pnc, r_bound, pnc, v)
89 #define DBG_OUT_R(r_pnc, r_bound, left, pnc, right, v)
90 #define DBG_OUT_L(l_pnc, l_bound, left, pnc, right, v)
92 #endif /* DEBUG_CONFIRM */
95 * Check, if the value of a node is != 0.
97 * This is a often needed case, so we handle here Confirm
100 int value_not_zero(ir_node *n, ir_node **confirm) {
101 #define RET_ON(x) if (x) { *confirm = n; return 1; }; break
104 ir_mode *mode = get_irn_mode(n);
108 while (get_irn_op(n) == op_Confirm) {
110 * Note: A Confirm is never after a Const. So,
111 * we simply can check the bound for being a Const
112 * without the fear that is might be hidden by a further Confirm.
114 tv = value_of(get_Confirm_bound(n));
115 if (tv == tarval_bad)
118 pnc = tarval_cmp(tv, get_mode_null(mode));
121 * Beware: C might by a NaN. It is not clear, what we should do
122 * than. Of course a NaN is != 0, but we might use this function
123 * to remove up Exceptions, and NaN's might generate Exception.
124 * So, we do NOT handle NaNs here for safety.
126 * Note that only the C != 0 case need additional checking.
128 switch (get_Confirm_cmp(n)) {
129 case pn_Cmp_Eq: /* n == C /\ C != 0 ==> n != 0 */
130 RET_ON(pnc != pn_Cmp_Eq && pnc != pn_Cmp_Uo);
131 case pn_Cmp_Lg: /* n != C /\ C == 0 ==> n != 0 */
132 RET_ON(pnc == pn_Cmp_Eq);
133 case pn_Cmp_Lt: /* n < C /\ C <= 0 ==> n != 0 */
134 RET_ON(pnc == pn_Cmp_Lt || pnc == pn_Cmp_Eq);
135 case pn_Cmp_Le: /* n <= C /\ C < 0 ==> n != 0 */
136 RET_ON(pnc == pn_Cmp_Lt);
137 case pn_Cmp_Ge: /* n >= C /\ C > 0 ==> n != 0 */
138 RET_ON(pnc == pn_Cmp_Gt);
139 case pn_Cmp_Gt: /* n > C /\ C >= 0 ==> n != 0 */
140 RET_ON(pnc == pn_Cmp_Gt || pnc == pn_Cmp_Eq);
145 /* there might be several Confirms one after other that form an interval */
146 n = get_Confirm_value(n);
150 if (tv == tarval_bad)
153 pnc = tarval_cmp(tv, get_mode_null(mode));
155 /* again, need check for NaN */
156 return (pnc != pn_Cmp_Eq) && (pnc != pn_Cmp_Uo);
159 } /* value_not_zero */
162 * Check, if the value of a node cannot represent a NULL pointer.
164 * - Casts are skipped
165 * - If sel_based_null_check_elim is enabled, all
166 * Sel nodes can be skipped.
167 * - A SymConst(entity) is NEVER a NULL pointer
168 * - Confirms are evaluated
170 int value_not_null(ir_node *n, ir_node **confirm) {
176 assert(mode_is_reference(get_irn_mode(n)));
177 if (get_opt_sel_based_null_check_elim()) {
178 /* skip all Sel nodes and Cast's */
179 while (op == op_Sel) {
180 n = skip_Cast(get_Sel_ptr(n));
184 if (op == op_SymConst && get_SymConst_kind(n) == symconst_addr_ent)
186 if (op == op_Const) {
187 tarval *tv = get_Const_tarval(n);
189 if (tv != tarval_bad && classify_tarval(tv) != TV_CLASSIFY_NULL)
191 } else if (op == op_Confirm) {
192 if (get_Confirm_cmp(n) == pn_Cmp_Lg &&
193 classify_Const(get_Confirm_bound(n)) == CNST_NULL) {
199 } /* value_not_null */
202 * Check, if the value of a node can be confirmed >= 0 or <= 0,
203 * If the mode of the value did not honor signed zeros, else
204 * check for >= 0 or < 0.
206 value_classify_sign classify_value_sign(ir_node *n) {
211 if (get_irn_op(n) != op_Confirm)
212 return value_classified_unknown;
214 tv = value_of(get_Confirm_bound(n));
215 if (tv == tarval_bad)
216 return value_classified_unknown;
218 mode = get_irn_mode(n);
221 * We can handle only >=, >, <, <= cases.
222 * We could handle == too, but this will be optimized into
225 * Note that for integer modes we have a slightly better
226 * optimization possibilities, so we handle this
229 cmp = get_Confirm_cmp(n);
234 * must be x < c <= 1 to be useful if integer mode and -0 = 0
235 * x < c <= 0 to be useful else
239 * must be x <= c < 1 to be useful if integer mode and -0 = 0
240 * x <= c < 0 to be useful else
242 c = mode_is_int(mode) && mode_honor_signed_zeros(mode) ?
243 get_mode_one(mode) : get_mode_null(mode);
245 ncmp = tarval_cmp(tv, c);
246 if (ncmp == pn_Cmp_Eq)
249 if (cmp != (ncmp ^ pn_Cmp_Eq))
250 return value_classified_unknown;
253 return value_classified_negative;
257 * must be x >= c > -1 to be useful if integer mode
258 * x >= c >= 0 to be useful else
262 * must be x > c >= -1 to be useful if integer mode
263 * x > c >= 0 to be useful else
265 if (mode_is_int(mode)) {
266 c = get_mode_minus_one(mode);
268 ncmp = tarval_cmp(tv, c);
269 if (ncmp == pn_Cmp_Eq)
272 if (cmp != (ncmp ^ pn_Cmp_Eq))
273 return value_classified_unknown;
275 c = get_mode_minus_one(mode);
277 ncmp = tarval_cmp(tv, c);
279 if (ncmp != pn_Cmp_Eq && ncmp != pn_Cmp_Gt)
280 return value_classified_unknown;
284 return value_classified_positive;
287 return value_classified_unknown;
289 } /* classify_value_sign */
292 * construct an interval from a value
294 * @return the filled interval or NULL if no interval
295 * can be created (happens only on floating point
297 static interval_t *get_interval_from_tv(interval_t *iv, tarval *tv) {
298 ir_mode *mode = get_tarval_mode(tv);
300 if (tv == tarval_bad) {
301 if (mode_is_float(mode)) {
302 /* NaN could be included which we cannot handle */
303 iv->min = tarval_bad;
304 iv->max = tarval_bad;
305 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
309 iv->min = get_mode_min(mode);
310 iv->max = get_mode_max(mode);
311 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
316 if (mode_is_float(mode)) {
317 if (tv == get_mode_NAN(mode)) {
318 /* arg, we cannot handle NaN's. */
319 iv->min = tarval_bad;
320 iv->max = tarval_bad;
321 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
329 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
332 } /* get_interval_from_tv */
335 * construct an interval from a Confirm
337 * @param iv an empty interval, will be filled
338 * @param bound the bound value
339 * @param pnc the Confirm compare relation
341 * @return the filled interval or NULL if no interval
342 * can be created (happens only on floating point
344 static interval_t *get_interval(interval_t *iv, ir_node *bound, pn_Cmp pnc) {
345 ir_mode *mode = get_irn_mode(bound);
346 tarval *tv = value_of(bound);
348 if (tv == tarval_bad) {
349 /* There is nothing we could do here. For integer
350 * modes we could return [-oo, +oo], but there is
351 * nothing we could deduct from such an interval.
352 * So, speed things up and return unknown.
354 iv->min = tarval_bad;
355 iv->max = tarval_bad;
356 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
360 if (mode_is_float(mode)) {
361 if (tv == get_mode_NAN(mode)) {
362 /* arg, we cannot handle NaN's. */
363 iv->min = tarval_bad;
364 iv->max = tarval_bad;
365 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
371 /* check which side is known */
377 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
382 iv->min = get_mode_min(mode);
384 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
389 iv->min = get_mode_min(mode);
391 iv->flags = MIN_INCLUDED | MAX_EXCLUDED;
397 iv->max = get_mode_max(mode);
398 iv->flags = MIN_EXCLUDED | MAX_INCLUDED;
404 iv->max = get_mode_max(mode);
405 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
410 * Ordered means, that at least neither
411 * our bound nor our value ara NaN's
414 iv->min = get_mode_min(mode);
415 iv->max = get_mode_max(mode);
416 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
421 * We do not handle UNORDERED, as a NaN
422 * could be included in the interval.
424 iv->min = tarval_bad;
425 iv->max = tarval_bad;
426 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
430 if (iv->min != tarval_bad && iv->max != tarval_bad)
436 * Try to evaluate l_iv pnc r_iv.
438 * @param l_iv the left interval
439 * @param r_iv the right interval
440 * @param pnc the compare relation
443 * tarval_b_true or tarval_b_false it it can be evaluated,
446 static tarval *(compare_iv)(const interval_t *l_iv, const interval_t *r_iv, pn_Cmp pnc) {
449 tarval *tv_true = tarval_b_true, *tv_false = tarval_b_false;
451 /* if one interval contains NaNs, we cannot evaluate anything */
452 if (! l_iv || ! r_iv)
455 /* we can only check ordered relations */
456 if (pnc & pn_Cmp_Uo) {
459 pnc = get_negated_pnc(pnc, get_tarval_mode(l_iv->min));
465 /* if we have > or >=, we do the inverse to save some cases */
466 if (pnc == pn_Cmp_Ge || pnc == pn_Cmp_Gt) {
469 pnc = get_inversed_pnc(pnc);
475 /* now, only the following cases remains */
478 /* two intervals can be compared for equality only if they are a single value */
479 if (l_iv->min == l_iv->max && r_iv->min == r_iv->max)
480 return tarval_cmp(l_iv->min, r_iv->min) == pn_Cmp_Eq ? tv_true : tv_false;
482 /* if both intervals do not intersect, it is never equal */
483 res = tarval_cmp(l_iv->max, r_iv->min);
485 /* b < c ==> [a,b] != [c,d] */
486 if (res == pn_Cmp_Lt)
489 /* b <= c ==> [a,b) != [c,d] AND [a,b] != (c,d] */
490 if ((l_iv->flags & MAX_EXCLUDED || r_iv->flags & MIN_EXCLUDED)
491 && (res == pn_Cmp_Eq))
494 res = tarval_cmp(r_iv->max, l_iv->min);
496 /* d < a ==> [c,d] != [a,b] */
497 if (res == pn_Cmp_Lt)
500 /* d <= a ==> [c,d) != [a,b] AND [c,d] != (a,b] */
501 if ((r_iv->flags & MAX_EXCLUDED || l_iv->flags & MIN_EXCLUDED)
502 && (res == pn_Cmp_Eq))
507 /* two intervals can be compared for not equality only if they are a single value */
508 if (l_iv->min == l_iv->max && r_iv->min == r_iv->max)
509 return tarval_cmp(l_iv->min, r_iv->min) != pn_Cmp_Eq ? tv_true : tv_false;
513 res = tarval_cmp(l_iv->max, r_iv->min);
515 /* [a, b] < [c, d] <==> b < c */
516 if (res == pn_Cmp_Lt)
519 /* if one border is excluded, b <= c is enough */
520 if ((l_iv->flags & MAX_EXCLUDED || r_iv->flags & MIN_EXCLUDED) &&
524 /* [a, b] >= [c, d] <==> a > d */
525 res = tarval_cmp(l_iv->min, r_iv->max);
526 if (res == pn_Cmp_Gt)
529 /* if one border is excluded, a >= d is enough */
530 if ((l_iv->flags & MIN_EXCLUDED || r_iv->flags & MAX_EXCLUDED) &&
536 /* [a, b) <= [c, d] or [a, b] <= (c, d] <==> b <= c */
537 flags = (l_iv->flags & MAX_EXCLUDED) | (r_iv->flags & MIN_EXCLUDED);
539 res = tarval_cmp(l_iv->max, r_iv->min);
541 if (res == pn_Cmp_Lt || res == pn_Cmp_Eq)
545 res = tarval_cmp(l_iv->min, r_iv->max);
547 /* [a, b] > [c, d] <==> a > d */
548 if (res == pn_Cmp_Gt)
551 /* if one border is excluded, a >= d is enough */
552 if ((l_iv->flags & MIN_EXCLUDED || r_iv->flags & MAX_EXCLUDED) &&
558 /* Hmm. if both are intervals, we can find an order */
568 * Returns non-zero, if a given relation is transitive.
570 static int is_transitive(pn_Cmp pnc) {
571 return (pn_Cmp_False < pnc && pnc < pn_Cmp_Lg);
572 } /* is_transitive */
576 * Return the value of a Cmp if one or both predecessors
579 * @param cmp the Cmp node
580 * @param left the left operand of the Cmp
581 * @param right the right operand of the Cmp
582 * @param pnc the compare relation
584 tarval *computed_value_Cmp_Confirm(ir_node *cmp, ir_node *left, ir_node *right, pn_Cmp pnc) {
586 pn_Cmp l_pnc, res_pnc, neg_pnc;
587 interval_t l_iv, r_iv;
591 if (get_irn_op(right) == op_Confirm) {
594 /* we want the Confirm on the left side */
599 pnc = get_inversed_pnc(pnc);
600 } else if (get_irn_op(left) != op_Confirm) {
601 /* no Confirm on either one side, finish */
605 /* ok, here at least left is a Confirm, right might be */
606 l_bound = get_Confirm_bound(left);
607 l_pnc = get_Confirm_cmp(left);
609 if (get_irn_op(right) == op_Confirm) {
611 * both sides are Confirm's. Check some rare cases first.
613 ir_node *r_bound = get_Confirm_bound(right);
614 pn_Cmp r_pnc = get_Confirm_cmp(right);
617 * some check can be made WITHOUT constant bounds
619 if (r_bound == l_bound) {
620 if (is_transitive(l_pnc)) {
621 pn_Cmp r_inc_pnc = get_inversed_pnc(r_pnc);
624 * triangle inequality:
626 * a CMP B && B CMP b => a CMP b, !(a ~CMP b)
628 * We handle correctly cases with some <=/>= here
630 if ((l_pnc & ~pn_Cmp_Eq) == (r_inc_pnc & ~pn_Cmp_Eq)) {
631 res_pnc = (l_pnc & ~pn_Cmp_Eq) | (l_pnc & r_inc_pnc & pn_Cmp_Eq);
633 if ((pnc == res_pnc) || ((pnc & ~pn_Cmp_Eq) == res_pnc)) {
634 DBG_OUT_TR(l_pnc, l_bound, r_pnc, r_bound, pnc, "true");
635 DBG_EVAL_CONFIRM(cmp);
636 return tarval_b_true;
638 pn_Cmp neg_pnc = get_negated_pnc(pnc, get_irn_mode(left));
640 if ((neg_pnc == res_pnc) || ((neg_pnc & ~pn_Cmp_Eq) == res_pnc)) {
641 DBG_OUT_TR(l_pnc, l_bound, r_pnc, r_bound, pnc, "false");
642 DBG_EVAL_CONFIRM(cmp);
643 return tarval_b_false;
651 * Here, we check only the right Confirm, as the left Confirms are
652 * checked later anyway.
654 if (left == r_bound) {
656 * l == bound(r) AND pnc(r) == pnc:
658 * We know that a CMP b and check for that
660 if ((r_pnc == pnc) || (r_pnc == (pnc & ~pn_Cmp_Eq))) {
661 DBG_OUT_R(r_pnc, r_bound, left, pnc, right, "true");
662 DBG_EVAL_CONFIRM(cmp);
663 return tarval_b_true;
666 * l == bound(r) AND pnc(r) != pnc:
668 * We know that a CMP b and check for a ~CMP b
671 mode = get_irn_mode(left);
672 neg_pnc = get_negated_pnc(pnc, mode);
674 if ((r_pnc == neg_pnc) || (r_pnc == (neg_pnc & ~pn_Cmp_Eq))) {
675 DBG_OUT_R(r_pnc, r_bound, left, pnc, right, "false");
676 DBG_EVAL_CONFIRM(cmp);
677 return tarval_b_false;
682 /* now, try interval magic */
684 get_interval(&l_iv, l_bound, l_pnc),
685 get_interval(&r_iv, r_bound, r_pnc),
688 if (tv != tarval_bad) {
689 DBG_EVAL_CONFIRM(cmp);
694 /* from Here, check only left Confirm */
697 * some checks can be made WITHOUT constant bounds
699 if (right == l_bound) {
701 * r == bound(l) AND pnc(l) == pnc:
703 * We know that a CMP b and check for that
705 if ((l_pnc == pnc) || (l_pnc == (pnc & ~pn_Cmp_Eq))) {
706 DBG_OUT_L(l_pnc, l_bound, left, pnc, right, "true");
707 DBG_EVAL_CONFIRM(cmp);
708 return tarval_b_true;
711 * r == bound(l) AND pnc(l) is Not(pnc):
713 * We know that a CMP b and check for a ~CMP b
716 mode = get_irn_mode(left);
717 neg_pnc = get_negated_pnc(pnc, mode);
719 if ((l_pnc == neg_pnc) || (l_pnc == (neg_pnc & ~pn_Cmp_Eq))) {
720 DBG_OUT_L(l_pnc, l_bound, left, pnc, right, "false");
721 DBG_EVAL_CONFIRM(cmp);
722 return tarval_b_false;
727 /* now, only right == Const can help */
728 tv = value_of(right);
730 if (tv != tarval_bad) {
732 get_interval(&l_iv, l_bound, l_pnc),
733 get_interval_from_tv(&r_iv, tv),
737 if (tv != tarval_bad)
738 DBG_EVAL_CONFIRM(cmp);
741 } /* computed_value_Cmp_Confirm */
745 * For debugging. Prints an interval into a string.
747 * @param buf address of a string buffer
748 * @param len length of the string buffer
749 * @param iv the interval
751 static int iv_snprintf(char *buf, size_t len, const interval_t *iv) {
752 char smin[64], smax[64];
755 tarval_snprintf(smin, sizeof(smin), iv->min);
757 if (iv->min != iv->max || (iv->flags & (MIN_EXCLUDED|MAX_EXCLUDED))) {
758 tarval_snprintf(smax, sizeof(smax), iv->max);
760 return snprintf(buf, len, "%c%s, %s%c",
761 iv->flags & MIN_EXCLUDED ? '(' : '[',
763 iv->flags & MAX_EXCLUDED ? ')' : ']'
766 return snprintf(buf, len, "%s", smin);
768 return snprintf(buf, len, "<UNKNOWN>");
772 * For debugging. Prints an interval compare.
774 * @param l_iv the left interval
775 * @param r_iv the right interval
776 * @param pnc the compare relation
778 static void print_iv_cmp(const interval_t *l_iv, const interval_t *r_iv, pn_Cmp pnc) {
779 char sl[128], sr[128];
781 iv_snprintf(sl, sizeof(sl), l_iv);
782 iv_snprintf(sr, sizeof(sr), r_iv);
784 ir_printf("%s %= %s", sl, pnc, sr);
788 * For debugging. call *compare_iv() and prints inputs and result.
790 * @param l_iv the left interval
791 * @param r_iv the right interval
792 * @param pnc the compare relation
794 static tarval *compare_iv_dbg(const interval_t *l_iv, const interval_t *r_iv, pn_Cmp pnc) {
795 tarval *tv = (compare_iv)(l_iv, r_iv, pnc);
797 if (tv == tarval_bad)
800 ir_printf("In %e:\n", get_irg_entity(current_ir_graph));
801 print_iv_cmp(l_iv, r_iv, pnc);
802 ir_printf(" = %T\n", tv);
804 } /* compare_iv_dbg */
806 #endif /* DEBUG_CONFIRM */