2 * Copyright (C) 1995-2008 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(const ir_node *n, ir_node_cnst_ptr *confirm) {
101 #define RET_ON(x) if (x) { *confirm = n; return 1; }; break
104 ir_mode *mode = get_irn_mode(n);
109 /* there might be several Confirms one after other that form an interval */
111 if (is_Minus(n) || is_Abs(n)) {
112 /* we can safely skip Minus and Abs when checking for != 0 */
120 * Note: A Confirm is never after a Const. So,
121 * we simply can check the bound for being a Const
122 * without the fear that is might be hidden by a further Confirm.
124 tv = value_of(get_Confirm_bound(n));
125 if (tv == tarval_bad)
128 pnc = tarval_cmp(tv, get_mode_null(mode));
131 * Beware: C might by a NaN. It is not clear, what we should do
132 * than. Of course a NaN is != 0, but we might use this function
133 * to remove up Exceptions, and NaN's might generate Exception.
134 * So, we do NOT handle NaNs here for safety.
136 * Note that only the C != 0 case need additional checking.
138 switch (get_Confirm_cmp(n)) {
139 case pn_Cmp_Eq: /* n == C /\ C != 0 ==> n != 0 */
140 RET_ON(pnc != pn_Cmp_Eq && pnc != pn_Cmp_Uo);
141 case pn_Cmp_Lg: /* n != C /\ C == 0 ==> n != 0 */
142 RET_ON(pnc == pn_Cmp_Eq);
143 case pn_Cmp_Lt: /* n < C /\ C <= 0 ==> n != 0 */
144 RET_ON(pnc == pn_Cmp_Lt || pnc == pn_Cmp_Eq);
145 case pn_Cmp_Le: /* n <= C /\ C < 0 ==> n != 0 */
146 RET_ON(pnc == pn_Cmp_Lt);
147 case pn_Cmp_Ge: /* n >= C /\ C > 0 ==> n != 0 */
148 RET_ON(pnc == pn_Cmp_Gt);
149 case pn_Cmp_Gt: /* n > C /\ C >= 0 ==> n != 0 */
150 RET_ON(pnc == pn_Cmp_Gt || pnc == pn_Cmp_Eq);
154 n = get_Confirm_value(n);
158 if (tv == tarval_bad)
161 pnc = tarval_cmp(tv, get_mode_null(mode));
163 /* again, need check for NaN */
164 return (pnc != pn_Cmp_Eq) && (pnc != pn_Cmp_Uo);
167 } /* value_not_zero */
170 * Check, if the value of a node cannot represent a NULL pointer.
172 * - Casts are skipped
173 * - If sel_based_null_check_elim is enabled, all
174 * Sel nodes can be skipped.
175 * - A SymConst(entity) is NEVER a NULL pointer
176 * - Confirms are evaluated
178 int value_not_null(const ir_node *n, ir_node_cnst_ptr *confirm) {
182 n = skip_Cast_const(n);
185 if (tarval_is_constant(tv) && ! tarval_is_null(tv))
188 assert(mode_is_reference(get_irn_mode(n)));
189 if (get_opt_sel_based_null_check_elim()) {
190 /* skip all Sel nodes and Cast's */
192 n = skip_Cast(get_Sel_ptr(n));
196 /* global references are never NULL */
198 } else if (n == get_irg_frame(current_ir_graph)) {
199 /* local references are never NULL */
202 /* check for more Confirms */
203 for (; is_Confirm(n); n = skip_Cast(get_Confirm_value(n))) {
204 if (get_Confirm_cmp(n) == pn_Cmp_Lg) {
205 ir_node *bound = get_Confirm_bound(n);
206 tarval *tv = value_of(bound);
208 if (tarval_is_null(tv)) {
216 } /* value_not_null */
219 * Check, if the value of a node can be confirmed >= 0 or <= 0,
220 * If the mode of the value did not honor signed zeros, else
221 * check for >= 0 or < 0.
223 value_classify_sign classify_value_sign(ir_node *n) {
230 ir_opcode code = get_irn_opcode(n);
240 return value_classified_unknown;
245 return value_classified_unknown;
247 tv = value_of(get_Confirm_bound(n));
248 if (tv == tarval_bad)
249 return value_classified_unknown;
251 mode = get_irn_mode(n);
254 * We can handle only >=, >, <, <= cases.
255 * We could handle == too, but this will be optimized into
258 * Note that for integer modes we have a slightly better
259 * optimization possibilities, so we handle this
262 cmp = get_Confirm_cmp(n);
267 * must be x < c <= 1 to be useful if integer mode and -0 = 0
268 * x < c <= 0 to be useful else
272 * must be x <= c < 1 to be useful if integer mode and -0 = 0
273 * x <= c < 0 to be useful else
275 c = mode_is_int(mode) && mode_honor_signed_zeros(mode) ?
276 get_mode_one(mode) : get_mode_null(mode);
278 ncmp = tarval_cmp(tv, c);
279 if (ncmp == pn_Cmp_Eq)
282 if (cmp != (ncmp ^ pn_Cmp_Eq))
283 return value_classified_unknown;
286 return value_classified_negative * negate;
290 * must be x >= c > -1 to be useful if integer mode
291 * x >= c >= 0 to be useful else
295 * must be x > c >= -1 to be useful if integer mode
296 * x > c >= 0 to be useful else
298 if (mode_is_int(mode)) {
299 c = get_mode_minus_one(mode);
301 ncmp = tarval_cmp(tv, c);
302 if (ncmp == pn_Cmp_Eq)
305 if (cmp != (ncmp ^ pn_Cmp_Eq))
306 return value_classified_unknown;
308 c = get_mode_minus_one(mode);
310 ncmp = tarval_cmp(tv, c);
312 if (ncmp != pn_Cmp_Eq && ncmp != pn_Cmp_Gt)
313 return value_classified_unknown;
317 return value_classified_positive * negate;
320 return value_classified_unknown;
322 } /* classify_value_sign */
325 * construct an interval from a value
327 * @return the filled interval or NULL if no interval
328 * can be created (happens only on floating point
330 static interval_t *get_interval_from_tv(interval_t *iv, tarval *tv) {
331 ir_mode *mode = get_tarval_mode(tv);
333 if (tv == tarval_bad) {
334 if (mode_is_float(mode)) {
335 /* NaN could be included which we cannot handle */
336 iv->min = tarval_bad;
337 iv->max = tarval_bad;
338 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
342 iv->min = get_mode_min(mode);
343 iv->max = get_mode_max(mode);
344 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
349 if (mode_is_float(mode)) {
350 if (tv == get_mode_NAN(mode)) {
351 /* arg, we cannot handle NaN's. */
352 iv->min = tarval_bad;
353 iv->max = tarval_bad;
354 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
362 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
365 } /* get_interval_from_tv */
368 * construct an interval from a Confirm
370 * @param iv an empty interval, will be filled
371 * @param bound the bound value
372 * @param pnc the Confirm compare relation
374 * @return the filled interval or NULL if no interval
375 * can be created (happens only on floating point
377 static interval_t *get_interval(interval_t *iv, ir_node *bound, pn_Cmp pnc) {
378 ir_mode *mode = get_irn_mode(bound);
379 tarval *tv = value_of(bound);
381 if (tv == tarval_bad) {
382 /* There is nothing we could do here. For integer
383 * modes we could return [-oo, +oo], but there is
384 * nothing we could deduct from such an interval.
385 * So, speed things up and return unknown.
387 iv->min = tarval_bad;
388 iv->max = tarval_bad;
389 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
393 if (mode_is_float(mode)) {
394 if (tv == get_mode_NAN(mode)) {
395 /* arg, we cannot handle NaN's. */
396 iv->min = tarval_bad;
397 iv->max = tarval_bad;
398 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
404 /* check which side is known */
410 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
415 iv->min = get_mode_min(mode);
417 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
422 iv->min = get_mode_min(mode);
424 iv->flags = MIN_INCLUDED | MAX_EXCLUDED;
430 iv->max = get_mode_max(mode);
431 iv->flags = MIN_EXCLUDED | MAX_INCLUDED;
437 iv->max = get_mode_max(mode);
438 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
443 * Ordered means, that at least neither
444 * our bound nor our value ara NaN's
447 iv->min = get_mode_min(mode);
448 iv->max = get_mode_max(mode);
449 iv->flags = MIN_INCLUDED | MAX_INCLUDED;
454 * We do not handle UNORDERED, as a NaN
455 * could be included in the interval.
457 iv->min = tarval_bad;
458 iv->max = tarval_bad;
459 iv->flags = MIN_EXCLUDED | MAX_EXCLUDED;
463 if (iv->min != tarval_bad && iv->max != tarval_bad)
469 * Try to evaluate l_iv pnc r_iv.
471 * @param l_iv the left interval
472 * @param r_iv the right interval
473 * @param pnc the compare relation
476 * tarval_b_true or tarval_b_false it it can be evaluated,
479 static tarval *(compare_iv)(const interval_t *l_iv, const interval_t *r_iv, pn_Cmp pnc) {
482 tarval *tv_true = tarval_b_true, *tv_false = tarval_b_false;
484 /* if one interval contains NaNs, we cannot evaluate anything */
485 if (! l_iv || ! r_iv)
488 /* we can only check ordered relations */
489 if (pnc & pn_Cmp_Uo) {
492 pnc = get_negated_pnc(pnc, get_tarval_mode(l_iv->min));
498 /* if we have > or >=, we do the inverse to save some cases */
499 if (pnc == pn_Cmp_Ge || pnc == pn_Cmp_Gt) {
502 pnc = get_inversed_pnc(pnc);
508 /* now, only the following cases remains */
511 /* two intervals can be compared for equality only if they are a single value */
512 if (l_iv->min == l_iv->max && r_iv->min == r_iv->max)
513 return tarval_cmp(l_iv->min, r_iv->min) == pn_Cmp_Eq ? tv_true : tv_false;
515 /* if both intervals do not intersect, it is never equal */
516 res = tarval_cmp(l_iv->max, r_iv->min);
518 /* b < c ==> [a,b] != [c,d] */
519 if (res == pn_Cmp_Lt)
522 /* b <= c ==> [a,b) != [c,d] AND [a,b] != (c,d] */
523 if ((l_iv->flags & MAX_EXCLUDED || r_iv->flags & MIN_EXCLUDED)
524 && (res == pn_Cmp_Eq))
527 res = tarval_cmp(r_iv->max, l_iv->min);
529 /* d < a ==> [c,d] != [a,b] */
530 if (res == pn_Cmp_Lt)
533 /* d <= a ==> [c,d) != [a,b] AND [c,d] != (a,b] */
534 if ((r_iv->flags & MAX_EXCLUDED || l_iv->flags & MIN_EXCLUDED)
535 && (res == pn_Cmp_Eq))
540 /* two intervals can be compared for not equality only if they are a single value */
541 if (l_iv->min == l_iv->max && r_iv->min == r_iv->max)
542 return tarval_cmp(l_iv->min, r_iv->min) != pn_Cmp_Eq ? tv_true : tv_false;
546 res = tarval_cmp(l_iv->max, r_iv->min);
548 /* [a, b] < [c, d] <==> b < c */
549 if (res == pn_Cmp_Lt)
552 /* if one border is excluded, b <= c is enough */
553 if ((l_iv->flags & MAX_EXCLUDED || r_iv->flags & MIN_EXCLUDED) &&
557 /* [a, b] >= [c, d] <==> a > d */
558 res = tarval_cmp(l_iv->min, r_iv->max);
559 if (res == pn_Cmp_Gt)
562 /* if one border is excluded, a >= d is enough */
563 if ((l_iv->flags & MIN_EXCLUDED || r_iv->flags & MAX_EXCLUDED) &&
569 /* [a, b) <= [c, d] or [a, b] <= (c, d] <==> b <= c */
570 flags = (l_iv->flags & MAX_EXCLUDED) | (r_iv->flags & MIN_EXCLUDED);
572 res = tarval_cmp(l_iv->max, r_iv->min);
574 if (res == pn_Cmp_Lt || res == pn_Cmp_Eq)
578 res = tarval_cmp(l_iv->min, r_iv->max);
580 /* [a, b] > [c, d] <==> a > d */
581 if (res == pn_Cmp_Gt)
584 /* if one border is excluded, a >= d is enough */
585 if ((l_iv->flags & MIN_EXCLUDED || r_iv->flags & MAX_EXCLUDED) &&
591 /* Hmm. if both are intervals, we can find an order */
601 * Returns non-zero, if a given relation is transitive.
603 static int is_transitive(pn_Cmp pnc) {
604 return (pn_Cmp_False < pnc && pnc < pn_Cmp_Lg);
605 } /* is_transitive */
608 * Return the value of a Cmp if one or both predecessors
611 * @param cmp the Cmp node
612 * @param left the left operand of the Cmp
613 * @param right the right operand of the Cmp
614 * @param pnc the compare relation
616 tarval *computed_value_Cmp_Confirm(ir_node *cmp, ir_node *left, ir_node *right, pn_Cmp pnc) {
618 pn_Cmp l_pnc, res_pnc, neg_pnc;
619 interval_t l_iv, r_iv;
623 if (is_Confirm(right)) {
624 /* we want the Confirm on the left side */
629 pnc = get_inversed_pnc(pnc);
630 } else if (! is_Confirm(left)) {
631 /* nothing more found */
633 goto check_null_case;
636 /* ok, here at least left is a Confirm, right might be */
637 l_bound = get_Confirm_bound(left);
638 l_pnc = get_Confirm_cmp(left);
640 if (is_Confirm(right)) {
642 * both sides are Confirm's. Check some rare cases first.
644 ir_node *r_bound = get_Confirm_bound(right);
645 pn_Cmp r_pnc = get_Confirm_cmp(right);
648 * some check can be made WITHOUT constant bounds
650 if (r_bound == l_bound) {
651 if (is_transitive(l_pnc)) {
652 pn_Cmp r_inc_pnc = get_inversed_pnc(r_pnc);
655 * triangle inequality:
657 * a CMP B && B CMP b => a CMP b, !(a ~CMP b)
659 * We handle correctly cases with some <=/>= here
661 if ((l_pnc & ~pn_Cmp_Eq) == (r_inc_pnc & ~pn_Cmp_Eq)) {
662 res_pnc = (l_pnc & ~pn_Cmp_Eq) | (l_pnc & r_inc_pnc & pn_Cmp_Eq);
664 if ((pnc == res_pnc) || ((pnc & ~pn_Cmp_Eq) == res_pnc)) {
665 DBG_OUT_TR(l_pnc, l_bound, r_pnc, r_bound, pnc, "true");
666 DBG_EVAL_CONFIRM(cmp);
667 return tarval_b_true;
669 pn_Cmp neg_pnc = get_negated_pnc(pnc, get_irn_mode(left));
671 if ((neg_pnc == res_pnc) || ((neg_pnc & ~pn_Cmp_Eq) == res_pnc)) {
672 DBG_OUT_TR(l_pnc, l_bound, r_pnc, r_bound, pnc, "false");
673 DBG_EVAL_CONFIRM(cmp);
674 return tarval_b_false;
682 * Here, we check only the right Confirm, as the left Confirms are
683 * checked later anyway.
685 if (left == r_bound) {
687 * l == bound(r) AND pnc(r) == pnc:
689 * We know that a CMP b and check for that
691 if ((r_pnc == pnc) || (r_pnc == (pnc & ~pn_Cmp_Eq))) {
692 DBG_OUT_R(r_pnc, r_bound, left, pnc, right, "true");
693 DBG_EVAL_CONFIRM(cmp);
694 return tarval_b_true;
697 * l == bound(r) AND pnc(r) != pnc:
699 * We know that a CMP b and check for a ~CMP b
702 mode = get_irn_mode(left);
703 neg_pnc = get_negated_pnc(pnc, mode);
705 if ((r_pnc == neg_pnc) || (r_pnc == (neg_pnc & ~pn_Cmp_Eq))) {
706 DBG_OUT_R(r_pnc, r_bound, left, pnc, right, "false");
707 DBG_EVAL_CONFIRM(cmp);
708 return tarval_b_false;
713 /* now, try interval magic */
715 get_interval(&l_iv, l_bound, l_pnc),
716 get_interval(&r_iv, r_bound, r_pnc),
719 if (tv != tarval_bad) {
720 DBG_EVAL_CONFIRM(cmp);
725 /* from Here, check only left Confirm */
728 * some checks can be made WITHOUT constant bounds
730 if (right == l_bound) {
732 * r == bound(l) AND pnc(l) == pnc:
734 * We know that a CMP b and check for that
736 if ((l_pnc == pnc) || (l_pnc == (pnc & ~pn_Cmp_Eq))) {
737 DBG_OUT_L(l_pnc, l_bound, left, pnc, right, "true");
738 DBG_EVAL_CONFIRM(cmp);
739 return tarval_b_true;
742 * r == bound(l) AND pnc(l) is Not(pnc):
744 * We know that a CMP b and check for a ~CMP b
747 mode = get_irn_mode(left);
748 neg_pnc = get_negated_pnc(pnc, mode);
750 if ((l_pnc == neg_pnc) || (l_pnc == (neg_pnc & ~pn_Cmp_Eq))) {
751 DBG_OUT_L(l_pnc, l_bound, left, pnc, right, "false");
752 DBG_EVAL_CONFIRM(cmp);
753 return tarval_b_false;
758 /* now, only right == Const can help */
759 tv = value_of(right);
761 if (tv != tarval_bad) {
763 get_interval(&l_iv, l_bound, l_pnc),
764 get_interval_from_tv(&r_iv, tv),
768 /* check some other cases */
769 if ((pnc == pn_Cmp_Eq || pnc == pn_Cmp_Lg) &&
770 is_Const(right) && is_Const_null(right)) {
771 /* for == 0 or != 0 we have some special tools */
772 ir_mode *mode = get_irn_mode(left);
773 const ir_node *dummy;
774 if (mode_is_reference(mode)) {
775 if (value_not_null(left, &dummy)) {
776 tv = pnc == pn_Cmp_Eq ? tarval_b_false : tarval_b_true;
779 if (value_not_zero(left, &dummy)) {
780 tv = pnc == pn_Cmp_Eq ? tarval_b_false : tarval_b_true;
786 if (tv != tarval_bad)
787 DBG_EVAL_CONFIRM(cmp);
790 } /* computed_value_Cmp_Confirm */
794 * For debugging. Prints an interval into a string.
796 * @param buf address of a string buffer
797 * @param len length of the string buffer
798 * @param iv the interval
800 static int iv_snprintf(char *buf, size_t len, const interval_t *iv) {
801 char smin[64], smax[64];
804 tarval_snprintf(smin, sizeof(smin), iv->min);
806 if (iv->min != iv->max || (iv->flags & (MIN_EXCLUDED|MAX_EXCLUDED))) {
807 tarval_snprintf(smax, sizeof(smax), iv->max);
809 return snprintf(buf, len, "%c%s, %s%c",
810 iv->flags & MIN_EXCLUDED ? '(' : '[',
812 iv->flags & MAX_EXCLUDED ? ')' : ']'
815 return snprintf(buf, len, "%s", smin);
817 return snprintf(buf, len, "<UNKNOWN>");
821 * For debugging. Prints an interval compare.
823 * @param l_iv the left interval
824 * @param r_iv the right interval
825 * @param pnc the compare relation
827 static void print_iv_cmp(const interval_t *l_iv, const interval_t *r_iv, pn_Cmp pnc) {
828 char sl[128], sr[128];
830 iv_snprintf(sl, sizeof(sl), l_iv);
831 iv_snprintf(sr, sizeof(sr), r_iv);
833 ir_printf("%s %= %s", sl, pnc, sr);
837 * For debugging. call *compare_iv() and prints inputs and result.
839 * @param l_iv the left interval
840 * @param r_iv the right interval
841 * @param pnc the compare relation
843 static tarval *compare_iv_dbg(const interval_t *l_iv, const interval_t *r_iv, pn_Cmp pnc) {
844 tarval *tv = (compare_iv)(l_iv, r_iv, pnc);
846 if (tv == tarval_bad)
849 ir_printf("In %e:\n", get_irg_entity(current_ir_graph));
850 print_iv_cmp(l_iv, r_iv, pnc);
851 ir_printf(" = %T\n", tv);
853 } /* compare_iv_dbg */
855 #endif /* DEBUG_CONFIRM */