2 * Copyright (C) 1995-2010 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 Data-flow driven minimal fixpoint value range propagation
23 * @author Christoph Mallon
33 #include "adt/xmalloc.h"
39 #include "irgraph_t.h"
42 #include "iroptimize.h"
47 #include "opt_manage.h"
50 * - Implement cleared/set bit calculation for Add, Sub, Minus, Mul, Div, Mod, Shl, Shr, Shrs, Rotl
51 * - Implement min/max calculation for And, Eor, Or, Not, Conv, Shl, Shr, Shrs, Rotl, Mux
52 * - Implement min/max calculation for Add, Sub, Minus, Mul, Div, Mod, Conv, Shl, Shr, Shrs, Rotl, Mux
55 /* Tables of the cleared/set bit lattice
57 * Encoding of the lattice
60 * 01 - impossible state, is zero /and/ one
61 * 10 T top, may be either zero or one
75 * Half adder, half subtractor, and, xor, or, Mux
87 * Full adder, full subtractor
118 * Assume: Xmin <= Xmax and no overflow
119 * A + B = (Amin + Bmin, Amax + Bmax)
120 * -A = (-Amax, -Amin)
121 * A - B = A + -B = (Amin (-B)min, Amax + (-B)max) = (Amin - Bmax, Amax - Bmin)
124 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
126 static struct obstack obst;
128 typedef struct bitinfo
130 ir_tarval* z; // safe zeroes, 0 = bit is zero, 1 = bit maybe is 1
131 ir_tarval* o; // safe ones, 0 = bit maybe is zero, 1 = bit is 1
134 typedef struct environment_t {
135 unsigned modified:1; /**< Set, if the graph was modified. */
138 static bool is_undefined(bitinfo const* const b)
140 return tarval_is_null(b->z) && tarval_is_all_one(b->o);
143 static inline bitinfo* get_bitinfo(ir_node const* const irn)
145 return (bitinfo*)get_irn_link(irn);
148 static int set_bitinfo(ir_node* const irn, ir_tarval* const z, ir_tarval* const o)
150 bitinfo* b = get_bitinfo(irn);
152 b = OALLOCZ(&obst, bitinfo);
153 set_irn_link(irn, b);
154 } else if (z == b->z && o == b->o) {
157 /* Assert monotonicity. */
158 assert(tarval_is_null(tarval_andnot(b->z, z)));
159 assert(tarval_is_null(tarval_andnot(o, b->o)));
163 DB((dbg, LEVEL_3, "%+F: 0:%T 1:%T\n", irn, z, o));
167 static int mode_is_intb(ir_mode const* const m)
169 return mode_is_int(m) || m == mode_b;
172 static int transfer(ir_node* const irn)
174 ir_tarval* const f = get_tarval_b_false();
175 ir_tarval* const t = get_tarval_b_true();
176 ir_mode* const m = get_irn_mode(irn);
180 if (is_Bad(irn)) return 0;
183 bitinfo* const b = get_bitinfo(get_nodes_block(irn));
185 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
187 /* Unreachble blocks might have no bitinfo. */
188 if (b == NULL || b->z == f) {
192 } else switch (get_irn_opcode(irn)) {
194 ir_node* const pred = get_Proj_pred(irn);
195 if (is_Start(pred)) {
196 goto result_unknown_X;
197 } else if (is_Cond(pred)) {
198 ir_node* const selector = get_Cond_selector(pred);
199 bitinfo* const b = get_bitinfo(selector);
200 if (is_undefined(b)) {
202 } else if (get_irn_mode(selector) == mode_b) {
204 if ((b->z == t) == get_Proj_proj(irn)) {
210 goto result_unknown_X;
213 long const val = get_Proj_proj(irn);
214 if (val != get_Cond_default_proj(pred)) {
215 ir_tarval* const tv = new_tarval_from_long(val, get_irn_mode(selector));
216 if (!tarval_is_null(tarval_andnot(tv, b->z)) ||
217 !tarval_is_null(tarval_andnot(b->o, tv))) {
218 // At least one bit differs.
220 #if 0 // TODO must handle default Proj
221 } else if (b->z == b->o && b->z == tv) {
225 goto result_unknown_X;
228 goto cannot_analyse_X;
232 goto cannot_analyse_X;
238 goto result_unknown_X;
242 DB((dbg, LEVEL_4, "cannot analyse %+F\n", irn));
248 } else if (is_Block(irn)) {
250 int const arity = get_Block_n_cfgpreds(irn);
253 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
254 for (i = 0; i != arity; ++i) {
255 bitinfo* const b = get_bitinfo(get_Block_cfgpred(irn, i));
256 if (b != NULL && b->z == t) {
263 ir_graph *const irg = get_Block_irg(irn);
265 irn == get_irg_start_block(irg) ||
266 irn == get_irg_end_block(irg);
276 } else if (mode_is_intb(m)) {
277 bitinfo* const b = get_bitinfo(get_nodes_block(irn));
279 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
281 if (b == NULL || b->z == f) {
283 z = get_tarval_null(m);
284 o = get_tarval_all_one(m);
285 } else if (is_Phi(irn)) {
286 ir_node* const block = get_nodes_block(irn);
287 int const arity = get_Phi_n_preds(irn);
290 z = get_tarval_null(m);
291 o = get_tarval_all_one(m);
292 for (i = 0; i != arity; ++i) {
293 bitinfo* const b_cfg = get_bitinfo(get_Block_cfgpred(block, i));
294 if (b_cfg != NULL && b_cfg->z != f) {
295 bitinfo* const b = get_bitinfo(get_Phi_pred(irn, i));
296 /* Only use input if it's not undefined. */
297 if (!is_undefined(b)) {
298 z = tarval_or( z, b->z);
299 o = tarval_and(o, b->o);
304 int const arity = get_irn_arity(irn);
307 /* Undefined if any input is undefined. */
308 for (i = 0; i != arity; ++i) {
309 ir_node* const pred = get_irn_n(irn, i);
310 bitinfo* const pred_b = get_bitinfo(pred);
311 if (pred_b != NULL && is_undefined(pred_b))
315 switch (get_irn_opcode(irn)) {
317 z = o = get_Const_tarval(irn);
322 ir_node* const v = get_Confirm_value(irn);
323 bitinfo* const b = get_bitinfo(v);
324 /* TODO Use bound and relation. */
327 if ((get_Confirm_relation(irn) & ~ir_relation_unordered) == ir_relation_equal) {
328 bitinfo* const bound_b = get_bitinfo(get_Confirm_bound(irn));
329 z = tarval_and(z, bound_b->z);
330 o = tarval_or( o, bound_b->o);
336 bitinfo* const l = get_bitinfo(get_Shl_left(irn));
337 bitinfo* const r = get_bitinfo(get_Shl_right(irn));
338 ir_tarval* const rz = r->z;
340 z = tarval_shl(l->z, rz);
341 o = tarval_shl(l->o, rz);
349 bitinfo* const l = get_bitinfo(get_Shr_left(irn));
350 bitinfo* const r = get_bitinfo(get_Shr_right(irn));
351 ir_tarval* const rz = r->z;
353 z = tarval_shr(l->z, rz);
354 o = tarval_shr(l->o, rz);
362 bitinfo* const l = get_bitinfo(get_Shrs_left(irn));
363 bitinfo* const r = get_bitinfo(get_Shrs_right(irn));
364 ir_tarval* const rz = r->z;
366 z = tarval_shrs(l->z, rz);
367 o = tarval_shrs(l->o, rz);
375 bitinfo* const l = get_bitinfo(get_Rotl_left(irn));
376 bitinfo* const r = get_bitinfo(get_Rotl_right(irn));
377 ir_tarval* const rz = r->z;
379 z = tarval_rotl(l->z, rz);
380 o = tarval_rotl(l->o, rz);
388 bitinfo* const l = get_bitinfo(get_Add_left(irn));
389 bitinfo* const r = get_bitinfo(get_Add_right(irn));
390 ir_tarval* const lz = l->z;
391 ir_tarval* const lo = l->o;
392 ir_tarval* const rz = r->z;
393 ir_tarval* const ro = r->o;
394 if (lz == lo && rz == ro) {
395 z = o = tarval_add(lz, rz);
397 // TODO improve: can only do lower disjoint bits
398 /* Determine where any of the operands has zero bits, i.e. where no
399 * carry out is generated if there is not carry in */
400 ir_tarval* const no_c_in_no_c_out = tarval_and(lz, rz);
401 /* Generate a mask of the lower consecutive zeroes: x | -x. In this
402 * range the addition is disjoint and therefore Add behaves like Or.
404 ir_tarval* const low_zero_mask = tarval_or(no_c_in_no_c_out, tarval_neg(no_c_in_no_c_out));
405 ir_tarval* const low_one_mask = tarval_not(low_zero_mask);
406 z = tarval_or( tarval_or(lz, rz), low_zero_mask);
407 o = tarval_and(tarval_or(lo, ro), low_one_mask);
413 bitinfo* const l = get_bitinfo(get_Sub_left(irn));
414 bitinfo* const r = get_bitinfo(get_Sub_right(irn));
415 if (l != NULL && r != NULL) { // Sub might subtract pointers.
416 ir_tarval* const lz = l->z;
417 ir_tarval* const lo = l->o;
418 ir_tarval* const rz = r->z;
419 ir_tarval* const ro = r->o;
420 if (lz == lo && rz == ro) {
421 z = o = tarval_sub(lz, rz, NULL);
422 } else if (tarval_is_null(tarval_andnot(rz, lo))) {
423 /* Every possible one of the subtrahend is backed by a safe one of the
424 * minuend, i.e. there are no borrows. */
425 // TODO extend no-borrow like carry for Add above
426 z = tarval_andnot(lz, ro);
427 o = tarval_andnot(lo, rz);
438 bitinfo* const l = get_bitinfo(get_Mul_left(irn));
439 bitinfo* const r = get_bitinfo(get_Mul_right(irn));
440 ir_tarval* const lz = l->z;
441 ir_tarval* const lo = l->o;
442 ir_tarval* const rz = r->z;
443 ir_tarval* const ro = r->o;
444 if (lz == lo && rz == ro) {
445 z = o = tarval_mul(lz, rz);
448 // Determine safe lower zeroes: x | -x.
449 ir_tarval* const lzn = tarval_or(lz, tarval_neg(lz));
450 ir_tarval* const rzn = tarval_or(rz, tarval_neg(rz));
451 // Concatenate safe lower zeroes.
452 if (tarval_cmp(lzn, rzn) == ir_relation_less) {
453 z = tarval_mul(tarval_eor(lzn, tarval_shl(lzn, get_tarval_one(m))), rzn);
455 z = tarval_mul(tarval_eor(rzn, tarval_shl(rzn, get_tarval_one(m))), lzn);
457 o = get_tarval_null(m);
463 bitinfo* const b = get_bitinfo(get_Minus_op(irn));
465 z = o = tarval_neg(b->z);
473 bitinfo* const l = get_bitinfo(get_And_left(irn));
474 bitinfo* const r = get_bitinfo(get_And_right(irn));
475 z = tarval_and(l->z, r->z);
476 o = tarval_and(l->o, r->o);
481 bitinfo* const l = get_bitinfo(get_Or_left(irn));
482 bitinfo* const r = get_bitinfo(get_Or_right(irn));
483 z = tarval_or(l->z, r->z);
484 o = tarval_or(l->o, r->o);
489 bitinfo* const l = get_bitinfo(get_Eor_left(irn));
490 bitinfo* const r = get_bitinfo(get_Eor_right(irn));
491 ir_tarval* const lz = l->z;
492 ir_tarval* const lo = l->o;
493 ir_tarval* const rz = r->z;
494 ir_tarval* const ro = r->o;
495 z = tarval_or(tarval_andnot(lz, ro), tarval_andnot(rz, lo));
496 o = tarval_or(tarval_andnot(ro, lz), tarval_andnot(lo, rz));
501 bitinfo* const b = get_bitinfo(get_Not_op(irn));
502 z = tarval_not(b->o);
503 o = tarval_not(b->z);
508 bitinfo* const b = get_bitinfo(get_Conv_op(irn));
509 if (b == NULL) // Happens when converting from float values.
511 z = tarval_convert_to(b->z, m);
512 o = tarval_convert_to(b->o, m);
517 bitinfo* const bf = get_bitinfo(get_Mux_false(irn));
518 bitinfo* const bt = get_bitinfo(get_Mux_true(irn));
519 bitinfo* const c = get_bitinfo(get_Mux_sel(irn));
523 } else if (c->z == f) {
527 z = tarval_or( bf->z, bt->z);
528 o = tarval_and(bf->o, bt->o);
534 bitinfo* const l = get_bitinfo(get_Cmp_left(irn));
535 bitinfo* const r = get_bitinfo(get_Cmp_right(irn));
536 if (l == NULL || r == NULL) {
537 goto result_unknown; // Cmp compares something we cannot evaluate.
539 ir_tarval* const lz = l->z;
540 ir_tarval* const lo = l->o;
541 ir_tarval* const rz = r->z;
542 ir_tarval* const ro = r->o;
543 ir_relation const relation = get_Cmp_relation(irn);
545 case ir_relation_less_greater:
546 if (!tarval_is_null(tarval_andnot(ro, lz)) ||
547 !tarval_is_null(tarval_andnot(lo, rz))) {
548 // At least one bit differs.
550 } else if (lz == lo && rz == ro && lz == rz) {
557 case ir_relation_equal:
558 if (!tarval_is_null(tarval_andnot(ro, lz)) ||
559 !tarval_is_null(tarval_andnot(lo, rz))) {
560 // At least one bit differs.
562 } else if (lz == lo && rz == ro && lz == rz) {
569 case ir_relation_less_equal:
570 case ir_relation_less:
571 /* TODO handle negative values */
572 if (tarval_is_negative(lz) || tarval_is_negative(lo) ||
573 tarval_is_negative(rz) || tarval_is_negative(ro))
576 if (tarval_cmp(lz, ro) & relation) {
577 /* Left upper bound is smaller(/equal) than right lower bound. */
579 } else if (!(tarval_cmp(lo, rz) & relation)) {
580 /* Left lower bound is not smaller(/equal) than right upper bound. */
587 case ir_relation_greater_equal:
588 case ir_relation_greater:
589 /* TODO handle negative values */
590 if (tarval_is_negative(lz) || tarval_is_negative(lo) ||
591 tarval_is_negative(rz) || tarval_is_negative(ro))
594 if (!(tarval_cmp(lz, ro) & relation)) {
595 /* Left upper bound is not greater(/equal) than right lower bound. */
597 } else if (tarval_cmp(lo, rz) & relation) {
598 /* Left lower bound is greater(/equal) than right upper bound. */
614 DB((dbg, LEVEL_4, "cannot analyse %+F\n", irn));
616 z = get_tarval_all_one(m);
617 o = get_tarval_null(m);
626 return set_bitinfo(irn, z, o);
629 static void first_round(ir_node* const irn, void* const env)
631 pdeq* const q = (pdeq*)env;
634 if (is_Phi(irn) || is_Block(irn)) {
635 /* Only Phis (and their users) need another round, if we did not have
636 * information about all their inputs in the first round, i.e. in loops. */
637 /* TODO inserts all Phis, should only insert Phis, which did no have all
638 * predecessors available */
643 static ir_node *make_bad_block(ir_graph *irg)
645 ir_node *bad = new_r_Bad(irg, mode_BB);
646 bitinfo *bb = get_bitinfo(bad);
648 ir_tarval* const f = get_tarval_b_false();
649 ir_tarval* const t = get_tarval_b_true();
650 set_bitinfo(bad, f, t); /* Undefined. */
655 static void apply_result(ir_node* const irn, void* ctx)
657 environment_t* env = (environment_t*)ctx;
665 block_b = get_bitinfo(irn);
666 /* Trivially unreachable blocks have no info. */
667 if (block_b == NULL || block_b->z == get_tarval_b_false()) {
668 ir_node *bad = make_bad_block(get_irn_irg(irn));
675 block = get_nodes_block(irn);
676 block_b = get_bitinfo(block);
677 /* Trivially unreachable blocks have no info. */
678 if (block_b == NULL || block_b->z == get_tarval_b_false()) {
679 /* Unreachable blocks might be replaced before the nodes in them. */
680 ir_mode *mode = get_irn_mode(irn);
681 ir_graph *irg = get_irn_irg(irn);
682 ir_node *bad = new_r_Bad(irg, mode);
688 b = get_bitinfo(irn);
690 if (is_Const(irn)) return; // It cannot get any better than a Const.
694 // Only display information if we could find out anything about the value.
695 DEBUG_ONLY(if (!tarval_is_all_one(z) || !tarval_is_null(o)))
696 DB((dbg, LEVEL_2, "%+F: 0:%T 1:%T%s\n", irn, z, o, z == o ? " --- constant" : ""));
698 // Replace node with constant value by Const.
700 ir_mode* const m = get_irn_mode(irn);
702 if (mode_is_intb(m)) {
703 ir_graph *irg = get_irn_irg(irn);
704 n = new_r_Const(irg, z);
705 } else if (m == mode_X) {
706 ir_graph* const irg = get_Block_irg(block);
707 if (z == get_tarval_b_true()) {
708 // Might produce an endless loop, so keep the block.
709 add_End_keepalive(get_irg_end(irg), block);
710 n = new_r_Jmp(block);
712 n = new_r_Bad(irg, mode_X);
713 /* Transferring analysis information to the bad node makes it a
714 * candidate for replacement. */
726 switch (get_irn_opcode(irn)) {
728 ir_node* const l = get_And_left(irn);
729 ir_node* const r = get_And_right(irn);
730 bitinfo const* const bl = get_bitinfo(l);
731 bitinfo const* const br = get_bitinfo(r);
732 if (bl->z == bl->o) {
733 if (tarval_is_null(tarval_andnot(br->z, bl->z))) {
734 DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
738 } else if (br->z == br->o) {
739 if (tarval_is_null(tarval_andnot(bl->z, br->z))) {
740 DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
749 ir_node* const l = get_Or_left(irn);
750 ir_node* const r = get_Or_right(irn);
751 bitinfo const* const bl = get_bitinfo(l);
752 bitinfo const* const br = get_bitinfo(r);
753 if (bl->z == bl->o) {
754 if (tarval_is_null(tarval_andnot(bl->o, br->o))) {
755 DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
759 } else if (br->z == br->o) {
760 if (tarval_is_null(tarval_andnot(br->o, bl->o))) {
761 DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
771 static void queue_users(pdeq* const q, ir_node* const n)
773 if (get_irn_mode(n) == mode_X) {
774 /* When the state of a control flow node changes, not only queue its
775 * successor blocks, but also the Phis in these blocks, because the Phis
776 * must reconsider this input path. */
778 foreach_out_edge(n, e) {
779 ir_node* const src = get_edge_src_irn(e);
781 /* should always be a block */
784 for (phi = get_Block_phis(src); phi; phi = get_Phi_next(phi))
790 foreach_out_edge(n, e) {
791 ir_node* const src = get_edge_src_irn(e);
792 if (get_irn_mode(src) == mode_T) {
801 static void clear_links(ir_node *irn, void *env)
804 set_irn_link(irn, NULL);
806 set_Block_phis(irn, NULL);
809 static void build_phi_lists(ir_node *irn, void *env)
813 add_Block_phi(get_nodes_block(irn), irn);
816 static ir_graph_state_t do_fixpoint_vrp(ir_graph* const irg)
819 ir_graph_state_t res = 0;
821 FIRM_DBG_REGISTER(dbg, "firm.opt.fp-vrp");
822 DB((dbg, LEVEL_1, "===> Performing constant propagation on %+F\n", irg));
826 ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK | IR_RESOURCE_PHI_LIST);
829 pdeq* const q = new_pdeq();
831 /* We need this extra step because the dom tree does not contain
832 * unreachable blocks in Firm. Moreover build phi list. */
833 irg_walk_anchors(irg, clear_links, build_phi_lists, NULL);
836 ir_tarval* const f = get_tarval_b_false();
837 ir_tarval* const t = get_tarval_b_true();
838 set_bitinfo(get_irg_end_block(irg), t, f); /* Reachable. */
841 /* TODO Improve iteration order. Best is reverse postorder in data flow
842 * direction and respecting loop nesting for fastest convergence. */
843 irg_walk_blkwise_dom_top_down(irg, NULL, first_round, q);
845 while (!pdeq_empty(q)) {
846 ir_node* const n = (ir_node*)pdeq_getl(q);
854 DB((dbg, LEVEL_2, "---> Applying analysis results\n"));
856 irg_walk_graph(irg, NULL, apply_result, &env);
858 if (! env.modified) {
859 res |= IR_GRAPH_STATE_CONSISTENT_DOMINANCE | IR_GRAPH_STATE_CONSISTENT_ENTITY_USAGE;
862 ir_free_resources(irg, IR_RESOURCE_IRN_LINK | IR_RESOURCE_PHI_LIST);
864 obstack_free(&obst, NULL);
869 optdesc_t opt_fpvrp = {
871 IR_GRAPH_STATE_NO_BADS | IR_GRAPH_STATE_NO_UNREACHABLE_CODE | IR_GRAPH_STATE_CONSISTENT_DOMINANCE | IR_GRAPH_STATE_CONSISTENT_OUT_EDGES,
875 void fixpoint_vrp(ir_graph* const irg)
877 perform_irg_optimization(irg, &opt_fpvrp);
880 ir_graph_pass_t *fixpoint_vrp_irg_pass(const char *name)
882 return def_graph_pass(name ? name : "fixpoint_vrp", fixpoint_vrp);