2 * abcremoval.c: Array bounds check removal
5 * Massimiliano Mantione (massi@ximian.com)
7 * (C) 2004 Ximian, Inc. http://www.ximian.com
12 #include <mono/metadata/debug-helpers.h>
13 #include <mono/metadata/mempool.h>
14 #include <mono/metadata/opcodes.h>
15 #include <mono/metadata/mempool-internals.h>
21 #include "abcremoval.h"
23 #if SIZEOF_VOID_P == 8
24 #define OP_PCONST OP_I8CONST
26 #define OP_PCONST OP_ICONST
30 #define TRACE_ABC_REMOVAL (verbose_level > 2)
31 #define REPORT_ABC_REMOVAL (verbose_level > 1)
34 * A little hack for the verbosity level.
35 * The verbosity level is stored in the cfg, but not all functions that must
36 * print something see the cfg, so we store the verbosity level here at the
37 * beginning of the algorithm.
38 * This is not thread safe (does not handle correctly different verbosity
39 * levels in different threads), and is not exact in case of dynamic changes
40 * of the verbosity level...
41 * Anyway, this is not needed, all that can happen is that something more
42 * (or less) is logged, the result is in any case correct.
44 static int verbose_level;
47 #define RELATION_BETWEEN_VALUES(value,related_value) (\
48 ((value) > (related_value))? MONO_GT_RELATION :\
49 (((value) < (related_value))? MONO_LT_RELATION : MONO_EQ_RELATION))
51 #define MAKE_VALUE_ANY(v) do{\
52 (v).type = MONO_ANY_SUMMARIZED_VALUE;\
55 #define MAKE_VALUE_RELATION_ANY(r) do{\
56 (r)->relation = MONO_ANY_RELATION;\
57 MAKE_VALUE_ANY((r)->related_value);\
60 #define INITIALIZE_VALUE_RELATION(r) do{\
61 MAKE_VALUE_RELATION_ANY((r));\
65 #define MONO_NEGATED_RELATION(r) ((~(r))&MONO_ANY_RELATION)
66 #define MONO_SYMMETRIC_RELATION(r) (((r)&MONO_EQ_RELATION)|(((r)&MONO_LT_RELATION)<<1)|((r&MONO_GT_RELATION)>>1))
71 print_relation (int relation) {
74 if (relation & MONO_LT_RELATION) {
78 if (relation & MONO_EQ_RELATION) {
85 if (relation & MONO_GT_RELATION) {
96 print_summarized_value (MonoSummarizedValue *value) {
97 switch (value->type) {
98 case MONO_ANY_SUMMARIZED_VALUE:
101 case MONO_CONSTANT_SUMMARIZED_VALUE:
102 printf ("CONSTANT %d", value->value.constant.value);
104 case MONO_VARIABLE_SUMMARIZED_VALUE:
105 printf ("VARIABLE %d, delta %d", value->value.variable.variable, value->value.variable.delta);
107 case MONO_PHI_SUMMARIZED_VALUE: {
110 for (phi = 0; phi < value->value.phi.number_of_alternatives; phi++) {
111 if (phi) printf (",");
112 printf ("%d", value->value.phi.phi_alternatives [phi]);
118 g_assert_not_reached ();
123 print_summarized_value_relation (MonoSummarizedValueRelation *relation) {
124 printf ("Relation ");
125 print_relation (relation->relation);
126 printf (" with value ");
127 print_summarized_value (&(relation->related_value));
132 print_summarized_value_relation_chain (MonoSummarizedValueRelation *relation) {
133 printf ("Relations:\n");
135 print_summarized_value_relation (relation);
137 relation = relation->next;
143 print_evaluation_context_status (MonoRelationsEvaluationStatus status) {
144 if (status == MONO_RELATIONS_EVALUATION_NOT_STARTED) {
145 printf ("EVALUATION_NOT_STARTED");
147 gboolean print_or = FALSE;
150 if (status & MONO_RELATIONS_EVALUATION_IN_PROGRESS) {
151 if (print_or) printf ("|");
152 printf ("EVALUATION_IN_PROGRESS");
155 if (status & MONO_RELATIONS_EVALUATION_COMPLETED) {
156 if (print_or) printf ("|");
157 printf ("EVALUATION_COMPLETED");
160 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
161 if (print_or) printf ("|");
162 printf ("RECURSIVELY_ASCENDING");
165 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
166 if (print_or) printf ("|");
167 printf ("RECURSIVELY_DESCENDING");
170 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
171 if (print_or) printf ("|");
172 printf ("RECURSIVELY_INDEFINITE");
181 print_evaluation_context_ranges (MonoRelationsEvaluationRanges *ranges) {
182 printf ("(ranges: zero [%d,%d], variable [%d,%d])", ranges->zero.lower, ranges->zero.upper, ranges->variable.lower, ranges->variable.upper);
186 print_evaluation_context (MonoRelationsEvaluationContext *context) {
187 printf ("Context status: ");
188 print_evaluation_context_status (context->status);
189 if (context->status & (MONO_RELATIONS_EVALUATION_IN_PROGRESS|MONO_RELATIONS_EVALUATION_COMPLETED)) {
190 print_evaluation_context_ranges (&(context->ranges));
197 print_evaluation_area (MonoVariableRelationsEvaluationArea *area) {
199 printf ("Dump of evaluation area (%d variables):\n", area->cfg->num_varinfo);
200 for (i = 0; i < area->cfg->num_varinfo; i++) {
201 printf ("Variable %d: ", i);
202 print_evaluation_context (&(area->contexts [i]));
203 print_summarized_value_relation_chain (&(area->relations [i]));
208 print_evaluation_area_contexts (MonoVariableRelationsEvaluationArea *area) {
210 printf ("Dump of evaluation area contexts (%d variables):\n", area->cfg->num_varinfo);
211 for (i = 0; i < area->cfg->num_varinfo; i++) {
212 printf ("Variable %d: ", i);
213 print_evaluation_context (&(area->contexts [i]));
219 * Check if the delta of an integer variable value is safe with respect
220 * to the variable size in bytes and its kind (signed or unsigned).
221 * If the delta is not safe, make the value an "any".
223 static G_GNUC_UNUSED void
224 check_delta_safety (MonoVariableRelationsEvaluationArea *area, MonoSummarizedValue *value) {
225 if (value->type == MONO_VARIABLE_SUMMARIZED_VALUE) {
226 int variable = value->value.variable.variable;
227 int delta = value->value.variable.delta;
228 if ((area->variable_value_kind [variable]) & MONO_UNSIGNED_VALUE_FLAG) {
230 MAKE_VALUE_ANY (*value);
233 if (((area->variable_value_kind [variable]) & MONO_INTEGER_VALUE_SIZE_BITMASK) < 4) {
234 MAKE_VALUE_ANY (*value);
235 } else if (delta > 16) {
236 MAKE_VALUE_ANY (*value);
243 * get_relation_from_ins:
245 * Obtain relations from a MonoInst.
247 * result_value_kind: the "expected" kind of result;
248 * result: the "summarized" value
249 * returns the "actual" kind of result, if guessable (otherwise MONO_UNKNOWN_INTEGER_VALUE)
251 static MonoIntegerValueKind
252 get_relation_from_ins (MonoVariableRelationsEvaluationArea *area, MonoInst *ins, MonoSummarizedValueRelation *result, MonoIntegerValueKind result_value_kind)
254 MonoIntegerValueKind value_kind;
255 MonoSummarizedValue *value = &result->related_value;
257 if (ins->type == STACK_I8) {
258 value_kind = MONO_INTEGER_VALUE_SIZE_8;
259 } else if (ins->type == STACK_I4) {
260 value_kind = MONO_INTEGER_VALUE_SIZE_4;
262 value_kind = MONO_UNKNOWN_INTEGER_VALUE;
265 result->relation = MONO_EQ_RELATION;
266 MAKE_VALUE_ANY (*value);
268 switch (ins->opcode) {
270 value->type = MONO_CONSTANT_SUMMARIZED_VALUE;
271 value->value.constant.value = ins->inst_c0;
274 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
275 value->value.variable.variable = ins->sreg1;
276 value->value.variable.delta = 0;
279 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
280 value->value.variable.variable = ins->sreg1;
281 value->value.variable.delta = 0;
282 value_kind = MONO_INTEGER_VALUE_SIZE_8;
285 value->type = MONO_PHI_SUMMARIZED_VALUE;
286 value->value.phi.number_of_alternatives = *(ins->inst_phi_args);
287 value->value.phi.phi_alternatives = ins->inst_phi_args + 1;
290 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
291 value->value.variable.variable = ins->sreg1;
292 value->value.variable.delta = ins->inst_imm;
294 //check_delta_safety (area, result);
297 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
298 value->value.variable.variable = ins->sreg1;
299 value->value.variable.delta = ins->inst_imm;
301 //check_delta_safety (area, result);
304 /* The result of an unsigned remainder is 0 < x < the divisor */
305 result->relation = MONO_LT_RELATION;
306 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
307 value->value.variable.variable = ins->sreg2;
308 value->value.variable.delta = 0;
309 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
313 * We represent arrays by their length, so r1<-ldlen r2 is stored
314 * as r1 == r2 in the evaluation graph.
316 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
317 value->value.variable.variable = ins->sreg1;
318 value->value.variable.delta = 0;
319 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
322 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
323 value->value.variable.variable = ins->sreg1;
324 value->value.variable.delta = 0;
325 area->defs [ins->dreg] = ins;
328 /* The result is non-null */
329 result->relation = MONO_GT_RELATION;
330 value->type = MONO_CONSTANT_SUMMARIZED_VALUE;
331 value->value.constant.value = 0;
334 /* FIXME: Add more opcodes */
336 /* These opcodes are not currently handled while running SciMark, first
337 * column is the number of times the warning was shown:
369 * 12 outarg_vtretaddr
397 static MonoValueRelation
398 get_relation_from_branch_instruction (MonoInst *ins)
400 if (MONO_IS_COND_BRANCH_OP (ins)) {
401 CompRelation rel = mono_opcode_to_cond (ins->opcode);
405 return MONO_EQ_RELATION;
407 return MONO_NE_RELATION;
410 return MONO_LE_RELATION;
413 return MONO_GE_RELATION;
416 return MONO_LT_RELATION;
419 return MONO_GT_RELATION;
421 g_assert_not_reached ();
422 return MONO_ANY_RELATION;
425 return MONO_ANY_RELATION;
430 * Given a BB, find its entry condition and put its relations in a
431 * "MonoAdditionalVariableRelationsForBB" structure.
433 * relations: the resulting relations (entry condition of the given BB)
436 get_relations_from_previous_bb (MonoVariableRelationsEvaluationArea *area, MonoBasicBlock *bb, MonoAdditionalVariableRelationsForBB *relations)
438 MonoBasicBlock *in_bb;
439 MonoInst *ins, *compare, *branch;
440 MonoValueRelation branch_relation;
441 MonoValueRelation symmetric_relation;
444 INITIALIZE_VALUE_RELATION (&(relations->relation1.relation));
445 relations->relation1.relation.relation_is_static_definition = FALSE;
446 relations->relation1.relation.next = NULL;
447 relations->relation1.insertion_point = NULL;
448 relations->relation1.variable = -1;
449 INITIALIZE_VALUE_RELATION (&(relations->relation2.relation));
450 relations->relation2.relation.relation_is_static_definition = FALSE;
451 relations->relation2.relation.next = NULL;
452 relations->relation2.insertion_point = NULL;
453 relations->relation2.variable = -1;
455 if (bb->in_count == 1) { /* Should write the code to "sum" conditions... */
456 in_bb = bb->in_bb [0];
458 if ((in_bb->last_ins == NULL) || (in_bb->code == in_bb->last_ins))
461 for (ins = in_bb->code; ins->next != in_bb->last_ins; ins = ins->next)
466 branch_relation = get_relation_from_branch_instruction (branch);
468 if (branch_relation != MONO_ANY_RELATION) {
469 if (branch->inst_true_bb == bb) {
471 } else if (branch->inst_false_bb == bb) {
475 g_assert_not_reached ();
478 branch_relation = MONO_NEGATED_RELATION (branch_relation);
479 symmetric_relation = MONO_SYMMETRIC_RELATION (branch_relation);
481 /* FIXME: Other compare opcodes */
482 if (compare->opcode == OP_ICOMPARE) {
483 relations->relation1.variable = compare->sreg1;
484 relations->relation1.relation.relation = branch_relation;
485 relations->relation1.relation.related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
486 relations->relation1.relation.related_value.value.variable.variable = compare->sreg2;
487 relations->relation1.relation.related_value.value.variable.delta = 0;
489 relations->relation2.variable = compare->sreg2;
490 relations->relation2.relation.relation = symmetric_relation;
491 relations->relation2.relation.related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
492 relations->relation2.relation.related_value.value.variable.variable = compare->sreg1;
493 relations->relation2.relation.related_value.value.variable.delta = 0;
494 } else if (compare->opcode == OP_ICOMPARE_IMM) {
495 relations->relation1.variable = compare->sreg1;
496 relations->relation1.relation.relation = branch_relation;
497 relations->relation1.relation.related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
498 relations->relation1.relation.related_value.value.constant.value = compare->inst_imm;
505 * Add the given relations to the evaluation area.
506 * area: the evaluation area
507 * change: the relations that must be added
510 apply_change_to_evaluation_area (MonoVariableRelationsEvaluationArea *area, MonoAdditionalVariableRelation *change)
512 MonoSummarizedValueRelation *base_relation;
514 if (change->relation.relation != MONO_ANY_RELATION) {
515 base_relation = &(area->relations [change->variable]);
516 while ((base_relation->next != NULL) && (base_relation->next->relation_is_static_definition)) {
517 base_relation = base_relation->next;
519 change->insertion_point = base_relation;
520 change->relation.next = base_relation->next;
521 base_relation->next = &(change->relation);
526 * Remove the given relation from the evaluation area.
527 * change: the relation that must be removed
530 remove_change_from_evaluation_area (MonoAdditionalVariableRelation *change)
532 if (change->insertion_point != NULL) {
533 change->insertion_point->next = change->relation.next;
534 change->relation.next = NULL;
540 clean_contexts (MonoRelationsEvaluationContext *contexts, int number)
543 for (i = 0; i < number; i++) {
544 contexts [i].status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
550 * Perform the intersection of a range and a constant value (taking into
551 * account the relation that the value has with the range).
552 * range: the range that will be intersected with the value
553 * value: the value that will be intersected with the range
554 * relation: the relation between the range and the value
557 intersect_value( MonoRelationsEvaluationRange *range, int value, MonoValueRelation relation )
560 case MONO_NO_RELATION:
561 MONO_MAKE_RELATIONS_EVALUATION_RANGE_IMPOSSIBLE (*range);
563 case MONO_ANY_RELATION:
565 case MONO_EQ_RELATION:
566 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
567 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
569 case MONO_NE_RELATION: {
570 /* IMPROVEMENT Figure this out! (ignoring it is safe anyway) */
573 case MONO_LT_RELATION:
574 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (value));
576 case MONO_LE_RELATION:
577 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
579 case MONO_GT_RELATION:
580 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (value));
582 case MONO_GE_RELATION:
583 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
586 g_assert_not_reached();
592 * Perform the intersection of two pairs of ranges (taking into account the
593 * relation between the ranges and a given delta).
594 * ranges: the ranges that will be intersected
595 * other_ranges the other ranges that will be intersected
596 * delta: the delta between the pairs of ranges
597 * relation: the relation between the pairs of ranges
600 intersect_ranges( MonoRelationsEvaluationRanges *ranges, MonoRelationsEvaluationRanges *other_ranges, int delta, MonoValueRelation relation )
604 case MONO_NO_RELATION:
605 MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (*ranges);
607 case MONO_ANY_RELATION:
609 case MONO_EQ_RELATION:
610 MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (*ranges, *other_ranges);
612 case MONO_NE_RELATION: {
613 /* FIXME Figure this out! (ignoring it is safe anyway) */
616 case MONO_LT_RELATION:
617 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->zero.upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->zero.upper));
618 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->variable.upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->variable.upper));
620 case MONO_LE_RELATION:
621 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->zero.upper, other_ranges->zero.upper);
622 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->variable.upper, other_ranges->variable.upper);
624 case MONO_GT_RELATION:
625 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->zero.lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->zero.lower));
626 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->variable.lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->variable.lower));
628 case MONO_GE_RELATION:
629 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->zero.lower, other_ranges->zero.lower);
630 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->variable.lower, other_ranges->variable.lower);
633 g_assert_not_reached();
636 MonoRelationsEvaluationRanges translated_ranges = *other_ranges;
637 MONO_ADD_DELTA_SAFELY_TO_RANGES (translated_ranges, delta);
638 intersect_ranges( ranges, &translated_ranges, FALSE, relation );
643 * Recursive method that traverses the relation graph to evaluate the
644 * relation between two variables.
645 * At the end of the execution, the resulting ranges are in the context of
646 * the "starting" variable.
647 * area: the current evaluation area (it contains the relation graph and
648 * memory for all the evaluation contexts is already allocated)
649 * variable: starting variable (the value ranges in its context are the result
650 * of the execution of this procedure)
651 * target_variable: the variable with respect to which the starting variable
652 * is evaluated (tipically the starting variable is the index
653 * and the target one is the array (which means its length))
654 * father_context: the previous evaluation context in recursive invocations
655 * (or NULL for the first invocation)
658 evaluate_relation_with_target_variable (MonoVariableRelationsEvaluationArea *area, int variable, int target_variable, MonoRelationsEvaluationContext *father_context)
660 MonoRelationsEvaluationContext *context = &(area->contexts [variable]);
662 // First of all, we check the evaluation status
663 // (what must be done is *very* different in each case)
664 switch (context->status) {
665 case MONO_RELATIONS_EVALUATION_NOT_STARTED: {
666 MonoSummarizedValueRelation *relation = &(area->relations [variable]);
668 if (TRACE_ABC_REMOVAL) {
669 printf ("Evaluating variable %d (target variable %d)\n", variable, target_variable);
670 print_summarized_value_relation (relation);
674 // We properly inizialize the context
675 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
676 context->father = father_context;
677 MONO_MAKE_RELATIONS_EVALUATION_RANGES_WEAK (context->ranges);
679 // If we have found the target variable, we can set the range
680 // related to it in the context to "equal" (which is [0,0])
681 if (variable == target_variable) {
682 if (TRACE_ABC_REMOVAL) {
683 printf ("Target variable reached (%d), continuing to evaluate relations with constants\n", variable);
685 context->ranges.variable.lower = 0;
686 context->ranges.variable.upper = 0;
689 // Examine all relations for this variable (scan the list)
690 // The contribute of each relation will be intersected (logical and)
691 while (relation != NULL) {
692 context->current_relation = relation;
694 if (TRACE_ABC_REMOVAL) {
695 printf ("Processing (%d): ", variable);
696 print_summarized_value_relation (relation);
700 // We decie what to do according the the type of the related value
701 switch (relation->related_value.type) {
702 case MONO_ANY_SUMMARIZED_VALUE:
703 // No added information, skip it
705 case MONO_CONSTANT_SUMMARIZED_VALUE:
706 // Intersect range with constant (taking into account the relation)
707 intersect_value (&(context->ranges.zero), relation->related_value.value.constant.value, relation->relation);
709 case MONO_VARIABLE_SUMMARIZED_VALUE:
710 // Generally, evaluate related variable and intersect ranges.
711 // However, some check is necessary...
713 // If the relation is "ANY", nothing to do (no added information)
714 if (relation->relation != MONO_ANY_RELATION) {
715 int related_variable = relation->related_value.value.variable.variable;
716 MonoRelationsEvaluationContext *related_context = &(area->contexts [related_variable]);
718 // The second condition in the "or" avoids messing with "back edges" in the graph traversal
719 // (they are simply ignored instead of triggering the handling of recursion)
720 if ( (related_context->status == MONO_RELATIONS_EVALUATION_NOT_STARTED) || !
721 ((related_context->current_relation->related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) &&
722 (related_context->current_relation->related_value.value.variable.variable == variable))) {
723 // Evaluate the related variable
724 evaluate_relation_with_target_variable (area, related_variable, target_variable, context);
726 // Check if we are part of a recursive loop
727 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
728 if (TRACE_ABC_REMOVAL) {
729 printf ("Recursivity detected for variable %d (target variable %d), status ", variable, target_variable);
730 print_evaluation_context_status (context->status);
733 // If we are, check if the evaluation of the related variable is complete
734 if (related_context->status == MONO_RELATIONS_EVALUATION_COMPLETED) {
735 // If it is complete, we are part of a recursive definition.
736 // Since it is a *definition* (and definitions are evaluated *before*
737 // conditions because they are first in the list), intersection is not
738 // strictly necessary, we simply copy the ranges and apply the delta
739 context->ranges = related_context->ranges;
740 /* Delta has already been checked for over/under-flow when evaluating values */
741 MONO_ADD_DELTA_SAFELY_TO_RANGES (context->ranges, relation->related_value.value.variable.delta);
742 context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
743 if (TRACE_ABC_REMOVAL) {
744 printf (", ranges already computed, result: \n");
745 print_evaluation_context_ranges (&(context->ranges));
746 printf (" (delta is %d)\n", relation->related_value.value.variable.delta);
749 // If it is not complete, do nothing (we do not have enough information)
750 if (TRACE_ABC_REMOVAL) {
751 printf (", ranges not computed\n");
755 // If we are not (the common case) intersect the result
756 intersect_ranges( &(context->ranges), &(related_context->ranges), relation->related_value.value.variable.delta, relation->relation );
759 if (TRACE_ABC_REMOVAL) {
760 printf ("Relation is a back-edge in this traversal, skipping\n");
765 case MONO_PHI_SUMMARIZED_VALUE: {
766 // We must compute all PHI alternatives, combining the results (with a union, which is a logical "or"),
767 // and intersect this result with the ranges in the context; we must also take into account recursions
768 // (with loops that can be ascending, descending, or indefinite)
769 MonoRelationsEvaluationRanges phi_ranges;
771 gboolean is_ascending = FALSE;
772 gboolean is_descending = FALSE;
774 MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (phi_ranges);
775 for (phi = 0; phi < relation->related_value.value.phi.number_of_alternatives; phi++) {
776 int phi_alternative = relation->related_value.value.phi.phi_alternatives [phi];
777 evaluate_relation_with_target_variable (area, phi_alternative, target_variable, context);
779 // This means we are part of a recursive loop
780 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
781 if (TRACE_ABC_REMOVAL) {
782 printf ("Recursivity detected for variable %d (target variable %d), status ", variable, target_variable);
783 print_evaluation_context_status (context->status);
786 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
789 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
790 is_descending = TRUE;
792 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
794 is_descending = TRUE;
797 // Clear "recursivity" bits in the status (recursion has been handled)
798 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
800 MONO_RELATIONS_EVALUATION_RANGES_UNION (phi_ranges, area->contexts [phi_alternative].ranges);
804 // Apply the effects of all recursive loops
806 phi_ranges.zero.upper = INT_MAX;
807 phi_ranges.variable.upper = INT_MAX;
810 phi_ranges.zero.lower = INT_MIN;
811 phi_ranges.variable.lower = INT_MIN;
814 // Intersect final result
815 MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (context->ranges, phi_ranges);
819 g_assert_not_reached();
822 // Pass to next relation
823 relation = relation->next;
826 // Check if any recursivity bits are still in the status, and in any case clear them
827 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
828 if (TRACE_ABC_REMOVAL) {
829 printf ("Recursivity for variable %d (target variable %d) discards computation, status ", variable, target_variable);
830 print_evaluation_context_status (context->status);
833 // If yes, we did not have enough information (most likely we were evaluated inside a PHI, but we also
834 // depended on the same PHI, which was still in evaluation...), so clear the status to "NOT_STARTED"
835 // (if we will be evaluated again, the PHI will be already done, so our evaluation will succeed)
836 context->status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
838 if (TRACE_ABC_REMOVAL) {
839 printf ("Ranges for variable %d (target variable %d) computed: ", variable, target_variable);
840 print_evaluation_context_ranges (&(context->ranges));
843 // If not (the common case) the evaluation is complete, and the result is in the context
844 context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
848 case MONO_RELATIONS_EVALUATION_IN_PROGRESS: {
849 // This means we are in a recursive loop
850 MonoRelationsEvaluationContext *current_context = father_context;
851 MonoRelationsEvaluationContext *last_context = context->father;
852 gboolean evaluation_can_be_recursive = TRUE;
853 gboolean evaluation_is_definition = TRUE;
856 if (TRACE_ABC_REMOVAL) {
857 printf ("Evaluation of variable %d (target variable %d) already in progress\n", variable, target_variable);
858 print_evaluation_context (context);
859 print_summarized_value_relation (context->current_relation);
863 // We must check if the loop can be a recursive definition (we scan the whole loop)
864 while (current_context != last_context) {
865 if (current_context == NULL) {
866 printf ("Broken recursive ring in ABC removal\n");
867 g_assert_not_reached ();
870 if (current_context->current_relation->relation_is_static_definition) {
871 if (current_context->current_relation->related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
872 /* No need to check path_value for over/under-flow, since delta should be safe */
873 path_value += current_context->current_relation->related_value.value.variable.delta;
874 } else if (current_context->current_relation->related_value.type != MONO_PHI_SUMMARIZED_VALUE) {
875 evaluation_can_be_recursive = FALSE;
878 evaluation_is_definition = FALSE;
879 evaluation_can_be_recursive = FALSE;
882 current_context = current_context->father;
885 // If this is a recursive definition, we properly flag the status in all the involved contexts
886 if (evaluation_is_definition) {
887 MonoRelationsEvaluationStatus recursive_status;
888 if (evaluation_can_be_recursive) {
889 if (path_value > 0) {
890 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING;
891 } else if (path_value < 0) {
892 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING;
894 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
897 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
900 if (TRACE_ABC_REMOVAL) {
901 printf ("Recursivity accepted (");
902 print_evaluation_context_status (recursive_status);
906 current_context = father_context;
907 while (current_context != last_context) {
908 current_context->status |= recursive_status;
909 current_context = current_context->father;
912 if (TRACE_ABC_REMOVAL) {
913 printf ("Recursivity rejected (some relation in the cycle is not a defintion)\n");
918 case MONO_RELATIONS_EVALUATION_COMPLETED: {
922 if (TRACE_ABC_REMOVAL) {
923 printf ("Variable %d (target variable %d) already in a recursive ring, skipping\n", variable, target_variable);
924 print_evaluation_context (context);
925 print_summarized_value_relation (context->current_relation);
934 * Apply the given value kind to the given range
937 apply_value_kind_to_range (MonoRelationsEvaluationRange *range, MonoIntegerValueKind value_kind)
939 if (value_kind != MONO_UNKNOWN_INTEGER_VALUE) {
940 if (value_kind & MONO_UNSIGNED_VALUE_FLAG) {
941 if (range->lower < 0) {
944 if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
945 if (range->upper > 0xff) {
948 } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
949 if (range->upper > 0xffff) {
950 range->upper = 0xffff;
954 if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
955 if (range->lower < -0x80) {
956 range->lower = -0x80;
958 if (range->upper > 0x7f) {
961 } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
962 if (range->lower < -0x8000) {
963 range->lower = -0x8000;
965 if (range->upper > 0x7fff) {
966 range->upper = 0x7fff;
974 * Attempt the removal of bounds checks from a MonoInst.
976 * area: the current evaluation area (it contains the relation graph and
977 * memory for all the evaluation contexts is already allocated)
980 remove_abc_from_inst (MonoInst *ins, MonoVariableRelationsEvaluationArea *area)
982 /* FIXME: Add support for 'constant' arrays and constant indexes */
984 int array_variable = ins->sreg1;
985 int index_variable = ins->sreg2;
986 MonoRelationsEvaluationContext *array_context = &(area->contexts [array_variable]);
987 MonoRelationsEvaluationContext *index_context = &(area->contexts [index_variable]);
989 clean_contexts (area->contexts, area->cfg->next_vreg);
991 evaluate_relation_with_target_variable (area, index_variable, array_variable, NULL);
992 evaluate_relation_with_target_variable (area, array_variable, array_variable, NULL);
994 if ((index_context->ranges.zero.lower >=0) && ((index_context->ranges.variable.upper < 0)||(index_context->ranges.zero.upper < array_context->ranges.zero.lower))) {
995 if (REPORT_ABC_REMOVAL) {
996 printf ("ARRAY-ACCESS: removed bounds check on array %d with index %d\n",
997 array_variable, index_variable);
1001 if (TRACE_ABC_REMOVAL) {
1002 if (index_context->ranges.zero.lower >= 0) {
1003 printf ("ARRAY-ACCESS: Removed lower bound check on array %d with index %d\n", array_variable, index_variable);
1005 if (index_context->ranges.variable.upper < 0) {
1006 printf ("ARRAY-ACCESS: Removed upper bound check (through variable) on array %d with index %d\n", array_variable, index_variable);
1008 if (index_context->ranges.zero.upper < array_context->ranges.zero.lower) {
1009 printf ("ARRAY-ACCESS: Removed upper bound check (through constant) on array %d with index %d\n", array_variable, index_variable);
1016 eval_non_null (MonoVariableRelationsEvaluationArea *area, int reg)
1018 MonoRelationsEvaluationContext *context = &(area->contexts [reg]);
1020 clean_contexts (area->contexts, area->cfg->next_vreg);
1021 evaluate_relation_with_target_variable (area, reg, reg, NULL);
1023 return context->ranges.zero.lower > 0;
1027 add_non_null (MonoVariableRelationsEvaluationArea *area, MonoCompile *cfg, int reg,
1028 GSList **check_relations)
1030 MonoAdditionalVariableRelation *rel;
1032 rel = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoAdditionalVariableRelation));
1033 rel->variable = reg;
1034 rel->relation.relation = MONO_GT_RELATION;
1035 rel->relation.related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1036 rel->relation.related_value.value.constant.value = 0;
1038 apply_change_to_evaluation_area (area, rel);
1040 *check_relations = g_slist_append_mempool (cfg->mempool, *check_relations, rel);
1044 * Process a BB removing bounds checks from array accesses.
1045 * It does the following (in sequence):
1046 * - Get the BB entry condition
1047 * - Add its relations to the relation graph in the evaluation area
1048 * - Process all the MonoInst trees in the BB
1049 * - Recursively process all the children BBs in the dominator tree
1050 * - Remove the relations previously added to the relation graph
1052 * bb: the BB that must be processed
1053 * area: the current evaluation area (it contains the relation graph and
1054 * memory for all the evaluation contexts is already allocated)
1057 process_block (MonoCompile *cfg, MonoBasicBlock *bb, MonoVariableRelationsEvaluationArea *area) {
1060 MonoAdditionalVariableRelationsForBB additional_relations;
1061 GSList *dominated_bb, *l;
1062 GSList *check_relations = NULL;
1064 if (TRACE_ABC_REMOVAL) {
1065 printf ("\nProcessing block %d [dfn %d]...\n", bb->block_num, bb->dfn);
1068 if (bb->region != -1)
1071 get_relations_from_previous_bb (area, bb, &additional_relations);
1072 if (TRACE_ABC_REMOVAL) {
1073 if (additional_relations.relation1.relation.relation != MONO_ANY_RELATION) {
1074 printf ("Adding relation 1 on variable %d: ", additional_relations.relation1.variable);
1075 print_summarized_value_relation (&(additional_relations.relation1.relation));
1078 if (additional_relations.relation2.relation.relation != MONO_ANY_RELATION) {
1079 printf ("Adding relation 2 on variable %d: ", additional_relations.relation2.variable);
1080 print_summarized_value_relation (&(additional_relations.relation2.relation));
1084 apply_change_to_evaluation_area (area, &(additional_relations.relation1));
1085 apply_change_to_evaluation_area (area, &(additional_relations.relation2));
1088 for (ins = bb->code; ins; ins = ins->next) {
1089 MonoAdditionalVariableRelation *rel;
1090 int array_var, index_var;
1092 if (TRACE_ABC_REMOVAL) {
1093 printf ("Processing instruction %d\n", inst_index);
1097 if (ins->opcode == OP_BOUNDS_CHECK) { /* Handle OP_LDELEMA2D, too */
1098 if (TRACE_ABC_REMOVAL) {
1099 printf ("Attempting check removal...\n");
1102 array_var = ins->sreg1;
1103 index_var = ins->sreg2;
1105 remove_abc_from_inst (ins, area);
1107 /* We can derive additional relations from the bounds check */
1108 if (ins->opcode != OP_NOP) {
1109 rel = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoAdditionalVariableRelation));
1110 rel->variable = index_var;
1111 rel->relation.relation = MONO_LT_RELATION;
1112 rel->relation.related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
1113 rel->relation.related_value.value.variable.variable = array_var;
1114 rel->relation.related_value.value.variable.delta = 0;
1116 apply_change_to_evaluation_area (area, rel);
1118 check_relations = g_slist_append_mempool (cfg->mempool, check_relations, rel);
1120 rel = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoAdditionalVariableRelation));
1121 rel->variable = index_var;
1122 rel->relation.relation = MONO_GE_RELATION;
1123 rel->relation.related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1124 rel->relation.related_value.value.constant.value = 0;
1126 apply_change_to_evaluation_area (area, rel);
1128 check_relations = g_slist_append_mempool (cfg->mempool, check_relations, rel);
1132 if (ins->opcode == OP_CHECK_THIS) {
1133 if (eval_non_null (area, ins->sreg1)) {
1134 if (REPORT_ABC_REMOVAL)
1135 printf ("ARRAY-ACCESS: removed check_this instruction.\n");
1140 if (ins->opcode == OP_NOT_NULL)
1141 add_non_null (area, cfg, ins->sreg1, &check_relations);
1144 * FIXME: abcrem equates an array with its length,
1145 * so a = new int [100] implies a != null, but a = new int [0] doesn't.
1148 * Eliminate MONO_INST_FAULT flags if possible.
1150 if (COMPILE_LLVM (cfg) && (ins->opcode == OP_LDLEN ||
1151 ins->opcode == OP_BOUNDS_CHECK ||
1152 ins->opcode == OP_STRLEN ||
1153 (MONO_IS_LOAD_MEMBASE (ins) && (ins->flags & MONO_INST_FAULT)) ||
1154 (MONO_IS_STORE_MEMBASE (ins) && (ins->flags & MONO_INST_FAULT)))) {
1157 if (MONO_IS_STORE_MEMBASE (ins))
1158 reg = ins->inst_destbasereg;
1159 else if (MONO_IS_LOAD_MEMBASE (ins))
1160 reg = ins->inst_basereg;
1165 * This doesn't work because LLVM can move the non-faulting loads before the faulting
1166 * ones (test_0_llvm_moving_faulting_loads ()).
1167 * So only do it if we know the load cannot be moved before the instruction which ensures it is not
1168 * null (i.e. the def of its sreg).
1170 if (area->defs [reg] && area->defs [reg]->opcode == OP_NEWARR) {
1171 if (REPORT_ABC_REMOVAL)
1172 printf ("ARRAY-ACCESS: removed MONO_INST_FAULT flag.\n");
1173 ins->flags &= ~MONO_INST_FAULT;
1176 if (eval_non_null (area, reg)) {
1177 if (REPORT_ABC_REMOVAL)
1178 printf ("ARRAY-ACCESS: removed MONO_INST_FAULT flag.\n");
1179 ins->flags &= ~MONO_INST_FAULT;
1181 add_non_null (area, cfg, reg, &check_relations);
1187 if (TRACE_ABC_REMOVAL) {
1188 printf ("Processing block %d [dfn %d] done.\n", bb->block_num, bb->dfn);
1191 for (dominated_bb = bb->dominated; dominated_bb != NULL; dominated_bb = dominated_bb->next) {
1192 process_block (cfg, (MonoBasicBlock*) (dominated_bb->data), area);
1195 for (l = check_relations; l; l = l->next)
1196 remove_change_from_evaluation_area (l->data);
1198 remove_change_from_evaluation_area (&(additional_relations.relation1));
1199 remove_change_from_evaluation_area (&(additional_relations.relation2));
1202 static MonoIntegerValueKind
1203 type_to_value_kind (MonoType *type)
1206 return MONO_UNKNOWN_INTEGER_VALUE;
1207 switch (type->type) {
1209 return MONO_INTEGER_VALUE_SIZE_1;
1212 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
1215 return MONO_INTEGER_VALUE_SIZE_2;
1218 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
1221 return MONO_INTEGER_VALUE_SIZE_4;
1224 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
1227 return SIZEOF_VOID_P;
1230 return (MONO_UNSIGNED_VALUE_FLAG|SIZEOF_VOID_P);
1233 return MONO_INTEGER_VALUE_SIZE_8;
1236 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_8;
1238 return MONO_UNKNOWN_INTEGER_VALUE;
1243 * mono_perform_abc_removal:
1244 * @cfg: Control Flow Graph
1246 * Performs the ABC removal from a cfg in SSA form.
1247 * It does the following:
1248 * - Prepare the evaluation area
1249 * - Allocate memory for the relation graph in the evaluation area
1250 * (of course, only for variable definitions) and summarize there all
1251 * variable definitions
1252 * - Allocate memory for the evaluation contexts in the evaluation area
1253 * - Recursively process all the BBs in the dominator tree (it is enough
1254 * to invoke the processing on the entry BB)
1256 * cfg: the method code
1259 mono_perform_abc_removal (MonoCompile *cfg)
1261 MonoVariableRelationsEvaluationArea area;
1265 verbose_level = cfg->verbose_level;
1267 if (TRACE_ABC_REMOVAL) {
1268 printf ("\nRemoving array bound checks in %s\n", mono_method_full_name (cfg->method, TRUE));
1272 area.relations = (MonoSummarizedValueRelation *)
1273 mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation) * (cfg->next_vreg) * 2);
1274 area.contexts = (MonoRelationsEvaluationContext *)
1275 mono_mempool_alloc (cfg->mempool, sizeof (MonoRelationsEvaluationContext) * (cfg->next_vreg));
1276 area.variable_value_kind = (MonoIntegerValueKind *)
1277 mono_mempool_alloc (cfg->mempool, sizeof (MonoIntegerValueKind) * (cfg->next_vreg));
1278 area.defs = mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * cfg->next_vreg);
1279 for (i = 0; i < cfg->next_vreg; i++) {
1280 area.variable_value_kind [i] = MONO_UNKNOWN_INTEGER_VALUE;
1281 area.relations [i].relation = MONO_EQ_RELATION;
1282 area.relations [i].relation_is_static_definition = TRUE;
1283 MAKE_VALUE_ANY (area.relations [i].related_value);
1284 area.relations [i].next = NULL;
1285 area.defs [i] = NULL;
1288 for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
1291 if (TRACE_ABC_REMOVAL)
1292 printf ("\nABCREM BLOCK %d:\n", bb->block_num);
1294 for (ins = bb->code; ins; ins = ins->next) {
1295 const char *spec = INS_INFO (ins->opcode);
1297 if (spec [MONO_INST_DEST] == ' ' || MONO_IS_STORE_MEMBASE (ins))
1300 if (spec [MONO_INST_DEST] == 'i') {
1301 MonoIntegerValueKind effective_value_kind;
1302 MonoRelationsEvaluationRange range;
1303 MonoSummarizedValueRelation *type_relation;
1306 if (TRACE_ABC_REMOVAL)
1307 mono_print_ins (ins);
1309 var = get_vreg_to_inst (cfg, ins->dreg);
1311 area.variable_value_kind [ins->dreg] = type_to_value_kind (var->inst_vtype);
1313 effective_value_kind = get_relation_from_ins (&area, ins, &area.relations [ins->dreg], area.variable_value_kind [ins->dreg]);
1315 MONO_MAKE_RELATIONS_EVALUATION_RANGE_WEAK (range);
1316 apply_value_kind_to_range (&range, area.variable_value_kind [ins->dreg]);
1317 apply_value_kind_to_range (&range, effective_value_kind);
1319 if (range.upper < INT_MAX) {
1320 type_relation = (MonoSummarizedValueRelation *) mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation));
1321 type_relation->relation = MONO_LE_RELATION;
1322 type_relation->related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1323 type_relation->related_value.value.constant.value = range.upper;
1324 type_relation->relation_is_static_definition = TRUE;
1325 type_relation->next = area.relations [ins->dreg].next;
1326 area.relations [ins->dreg].next = type_relation;
1327 if (TRACE_ABC_REMOVAL) {
1328 printf ("[var%d <= %d]", ins->dreg, range.upper);
1331 if (range.lower > INT_MIN) {
1332 type_relation = (MonoSummarizedValueRelation *) mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation));
1333 type_relation->relation = MONO_GE_RELATION;
1334 type_relation->related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1335 type_relation->related_value.value.constant.value = range.lower;
1336 type_relation->relation_is_static_definition = TRUE;
1337 type_relation->next = area.relations [ins->dreg].next;
1338 area.relations [ins->dreg].next = type_relation;
1339 if (TRACE_ABC_REMOVAL) {
1340 printf ("[var%d >= %d]", ins->dreg, range.lower);
1343 if (TRACE_ABC_REMOVAL) {
1344 printf ("Summarized variable %d: ", ins->dreg);
1345 print_summarized_value (&(area.relations [ins->dreg].related_value));
1352 /* Add symmetric relations */
1353 for (i = 0; i < cfg->next_vreg; i++) {
1354 if (area.relations [i].related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1355 int related_index = cfg->next_vreg + i;
1356 int related_variable = area.relations [i].related_value.value.variable.variable;
1358 area.relations [related_index].relation = MONO_EQ_RELATION;
1359 area.relations [related_index].relation_is_static_definition = TRUE;
1360 area.relations [related_index].related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
1361 area.relations [related_index].related_value.value.variable.variable = i;
1362 area.relations [related_index].related_value.value.variable.delta = - area.relations [i].related_value.value.variable.delta;
1364 area.relations [related_index].next = area.relations [related_variable].next;
1365 area.relations [related_variable].next = &(area.relations [related_index]);
1367 if (TRACE_ABC_REMOVAL) {
1368 printf ("Added symmetric summarized value for variable variable %d (to %d): ", i, related_variable);
1369 print_summarized_value (&(area.relations [related_index].related_value));
1375 process_block (cfg, cfg->bblocks [0], &area);
1378 #endif /* DISABLE_JIT */