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_PHI_SUMMARIZED_VALUE;
280 value->value.phi.number_of_alternatives = *(ins->inst_phi_args);
281 value->value.phi.phi_alternatives = ins->inst_phi_args + 1;
284 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
285 value->value.variable.variable = ins->sreg1;
286 value->value.variable.delta = ins->inst_imm;
288 //check_delta_safety (area, result);
291 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
292 value->value.variable.variable = ins->sreg1;
293 value->value.variable.delta = ins->inst_imm;
295 //check_delta_safety (area, result);
298 /* The result of an unsigned remainder is 0 < x < the divisor */
299 result->relation = MONO_LT_RELATION;
300 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
301 value->value.variable.variable = ins->sreg2;
302 value->value.variable.delta = 0;
303 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
307 * We represent arrays by their length, so r1<-ldlen r2 is stored
308 * as r1 == r2 in the evaluation graph.
310 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
311 value->value.variable.variable = ins->sreg1;
312 value->value.variable.delta = 0;
313 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
316 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
317 value->value.variable.variable = ins->sreg1;
318 value->value.variable.delta = 0;
319 area->defs [ins->dreg] = ins;
322 /* The result is non-null */
323 result->relation = MONO_GT_RELATION;
324 value->type = MONO_CONSTANT_SUMMARIZED_VALUE;
325 value->value.constant.value = 0;
328 /* FIXME: Add more opcodes */
330 /* These opcodes are not currently handled while running SciMark, first
331 * column is the number of times the warning was shown:
363 * 12 outarg_vtretaddr
391 static MonoValueRelation
392 get_relation_from_branch_instruction (MonoInst *ins)
394 if (MONO_IS_COND_BRANCH_OP (ins)) {
395 CompRelation rel = mono_opcode_to_cond (ins->opcode);
399 return MONO_EQ_RELATION;
401 return MONO_NE_RELATION;
404 return MONO_LE_RELATION;
407 return MONO_GE_RELATION;
410 return MONO_LT_RELATION;
413 return MONO_GT_RELATION;
415 g_assert_not_reached ();
416 return MONO_ANY_RELATION;
419 return MONO_ANY_RELATION;
424 * Given a BB, find its entry condition and put its relations in a
425 * "MonoAdditionalVariableRelationsForBB" structure.
427 * relations: the resulting relations (entry condition of the given BB)
430 get_relations_from_previous_bb (MonoVariableRelationsEvaluationArea *area, MonoBasicBlock *bb, MonoAdditionalVariableRelationsForBB *relations)
432 MonoBasicBlock *in_bb;
433 MonoInst *ins, *compare, *branch;
434 MonoValueRelation branch_relation;
435 MonoValueRelation symmetric_relation;
438 INITIALIZE_VALUE_RELATION (&(relations->relation1.relation));
439 relations->relation1.relation.relation_is_static_definition = FALSE;
440 relations->relation1.relation.next = NULL;
441 relations->relation1.insertion_point = NULL;
442 relations->relation1.variable = -1;
443 INITIALIZE_VALUE_RELATION (&(relations->relation2.relation));
444 relations->relation2.relation.relation_is_static_definition = FALSE;
445 relations->relation2.relation.next = NULL;
446 relations->relation2.insertion_point = NULL;
447 relations->relation2.variable = -1;
449 if (bb->in_count == 1) { /* Should write the code to "sum" conditions... */
450 in_bb = bb->in_bb [0];
452 if ((in_bb->last_ins == NULL) || (in_bb->code == in_bb->last_ins))
455 for (ins = in_bb->code; ins->next != in_bb->last_ins; ins = ins->next)
460 branch_relation = get_relation_from_branch_instruction (branch);
462 if (branch_relation != MONO_ANY_RELATION) {
463 if (branch->inst_true_bb == bb) {
465 } else if (branch->inst_false_bb == bb) {
469 g_assert_not_reached ();
472 branch_relation = MONO_NEGATED_RELATION (branch_relation);
473 symmetric_relation = MONO_SYMMETRIC_RELATION (branch_relation);
475 /* FIXME: Other compare opcodes */
476 if (compare->opcode == OP_ICOMPARE) {
477 relations->relation1.variable = compare->sreg1;
478 relations->relation1.relation.relation = branch_relation;
479 relations->relation1.relation.related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
480 relations->relation1.relation.related_value.value.variable.variable = compare->sreg2;
481 relations->relation1.relation.related_value.value.variable.delta = 0;
483 relations->relation2.variable = compare->sreg2;
484 relations->relation2.relation.relation = symmetric_relation;
485 relations->relation2.relation.related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
486 relations->relation2.relation.related_value.value.variable.variable = compare->sreg1;
487 relations->relation2.relation.related_value.value.variable.delta = 0;
488 } else if (compare->opcode == OP_ICOMPARE_IMM) {
489 relations->relation1.variable = compare->sreg1;
490 relations->relation1.relation.relation = branch_relation;
491 relations->relation1.relation.related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
492 relations->relation1.relation.related_value.value.constant.value = compare->inst_imm;
499 * Add the given relations to the evaluation area.
500 * area: the evaluation area
501 * change: the relations that must be added
504 apply_change_to_evaluation_area (MonoVariableRelationsEvaluationArea *area, MonoAdditionalVariableRelation *change)
506 MonoSummarizedValueRelation *base_relation;
508 if (change->relation.relation != MONO_ANY_RELATION) {
509 base_relation = &(area->relations [change->variable]);
510 while ((base_relation->next != NULL) && (base_relation->next->relation_is_static_definition)) {
511 base_relation = base_relation->next;
513 change->insertion_point = base_relation;
514 change->relation.next = base_relation->next;
515 base_relation->next = &(change->relation);
520 * Remove the given relation from the evaluation area.
521 * change: the relation that must be removed
524 remove_change_from_evaluation_area (MonoAdditionalVariableRelation *change)
526 if (change->insertion_point != NULL) {
527 change->insertion_point->next = change->relation.next;
528 change->relation.next = NULL;
534 clean_contexts (MonoRelationsEvaluationContext *contexts, int number)
537 for (i = 0; i < number; i++) {
538 contexts [i].status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
544 * Perform the intersection of a range and a constant value (taking into
545 * account the relation that the value has with the range).
546 * range: the range that will be intersected with the value
547 * value: the value that will be intersected with the range
548 * relation: the relation between the range and the value
551 intersect_value( MonoRelationsEvaluationRange *range, int value, MonoValueRelation relation )
554 case MONO_NO_RELATION:
555 MONO_MAKE_RELATIONS_EVALUATION_RANGE_IMPOSSIBLE (*range);
557 case MONO_ANY_RELATION:
559 case MONO_EQ_RELATION:
560 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
561 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
563 case MONO_NE_RELATION: {
564 /* IMPROVEMENT Figure this out! (ignoring it is safe anyway) */
567 case MONO_LT_RELATION:
568 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (value));
570 case MONO_LE_RELATION:
571 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
573 case MONO_GT_RELATION:
574 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (value));
576 case MONO_GE_RELATION:
577 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
580 g_assert_not_reached();
586 * Perform the intersection of two pairs of ranges (taking into account the
587 * relation between the ranges and a given delta).
588 * ranges: the ranges that will be intersected
589 * other_ranges the other ranges that will be intersected
590 * delta: the delta between the pairs of ranges
591 * relation: the relation between the pairs of ranges
594 intersect_ranges( MonoRelationsEvaluationRanges *ranges, MonoRelationsEvaluationRanges *other_ranges, int delta, MonoValueRelation relation )
598 case MONO_NO_RELATION:
599 MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (*ranges);
601 case MONO_ANY_RELATION:
603 case MONO_EQ_RELATION:
604 MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (*ranges, *other_ranges);
606 case MONO_NE_RELATION: {
607 /* FIXME Figure this out! (ignoring it is safe anyway) */
610 case MONO_LT_RELATION:
611 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->zero.upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->zero.upper));
612 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->variable.upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->variable.upper));
614 case MONO_LE_RELATION:
615 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->zero.upper, other_ranges->zero.upper);
616 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->variable.upper, other_ranges->variable.upper);
618 case MONO_GT_RELATION:
619 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->zero.lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->zero.lower));
620 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->variable.lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->variable.lower));
622 case MONO_GE_RELATION:
623 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->zero.lower, other_ranges->zero.lower);
624 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->variable.lower, other_ranges->variable.lower);
627 g_assert_not_reached();
630 MonoRelationsEvaluationRanges translated_ranges = *other_ranges;
631 MONO_ADD_DELTA_SAFELY_TO_RANGES (translated_ranges, delta);
632 intersect_ranges( ranges, &translated_ranges, FALSE, relation );
637 * Recursive method that traverses the relation graph to evaluate the
638 * relation between two variables.
639 * At the end of the execution, the resulting ranges are in the context of
640 * the "starting" variable.
641 * area: the current evaluation area (it contains the relation graph and
642 * memory for all the evaluation contexts is already allocated)
643 * variable: starting variable (the value ranges in its context are the result
644 * of the execution of this procedure)
645 * target_variable: the variable with respect to which the starting variable
646 * is evaluated (tipically the starting variable is the index
647 * and the target one is the array (which means its length))
648 * father_context: the previous evaluation context in recursive invocations
649 * (or NULL for the first invocation)
652 evaluate_relation_with_target_variable (MonoVariableRelationsEvaluationArea *area, int variable, int target_variable, MonoRelationsEvaluationContext *father_context)
654 MonoRelationsEvaluationContext *context = &(area->contexts [variable]);
656 // First of all, we check the evaluation status
657 // (what must be done is *very* different in each case)
658 switch (context->status) {
659 case MONO_RELATIONS_EVALUATION_NOT_STARTED: {
660 MonoSummarizedValueRelation *relation = &(area->relations [variable]);
662 if (TRACE_ABC_REMOVAL) {
663 printf ("Evaluating variable %d (target variable %d)\n", variable, target_variable);
664 print_summarized_value_relation (relation);
668 // We properly inizialize the context
669 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
670 context->father = father_context;
671 MONO_MAKE_RELATIONS_EVALUATION_RANGES_WEAK (context->ranges);
673 // If we have found the target variable, we can set the range
674 // related to it in the context to "equal" (which is [0,0])
675 if (variable == target_variable) {
676 if (TRACE_ABC_REMOVAL) {
677 printf ("Target variable reached (%d), continuing to evaluate relations with constants\n", variable);
679 context->ranges.variable.lower = 0;
680 context->ranges.variable.upper = 0;
683 // Examine all relations for this variable (scan the list)
684 // The contribute of each relation will be intersected (logical and)
685 while (relation != NULL) {
686 context->current_relation = relation;
688 if (TRACE_ABC_REMOVAL) {
689 printf ("Processing (%d): ", variable);
690 print_summarized_value_relation (relation);
694 // We decie what to do according the the type of the related value
695 switch (relation->related_value.type) {
696 case MONO_ANY_SUMMARIZED_VALUE:
697 // No added information, skip it
699 case MONO_CONSTANT_SUMMARIZED_VALUE:
700 // Intersect range with constant (taking into account the relation)
701 intersect_value (&(context->ranges.zero), relation->related_value.value.constant.value, relation->relation);
703 case MONO_VARIABLE_SUMMARIZED_VALUE:
704 // Generally, evaluate related variable and intersect ranges.
705 // However, some check is necessary...
707 // If the relation is "ANY", nothing to do (no added information)
708 if (relation->relation != MONO_ANY_RELATION) {
709 int related_variable = relation->related_value.value.variable.variable;
710 MonoRelationsEvaluationContext *related_context = &(area->contexts [related_variable]);
712 // The second condition in the "or" avoids messing with "back edges" in the graph traversal
713 // (they are simply ignored instead of triggering the handling of recursion)
714 if ( (related_context->status == MONO_RELATIONS_EVALUATION_NOT_STARTED) || !
715 ((related_context->current_relation->related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) &&
716 (related_context->current_relation->related_value.value.variable.variable == variable))) {
717 // Evaluate the related variable
718 evaluate_relation_with_target_variable (area, related_variable, target_variable, context);
720 // Check if we are part of a recursive loop
721 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
722 if (TRACE_ABC_REMOVAL) {
723 printf ("Recursivity detected for variable %d (target variable %d), status ", variable, target_variable);
724 print_evaluation_context_status (context->status);
727 // If we are, check if the evaluation of the related variable is complete
728 if (related_context->status == MONO_RELATIONS_EVALUATION_COMPLETED) {
729 // If it is complete, we are part of a recursive definition.
730 // Since it is a *definition* (and definitions are evaluated *before*
731 // conditions because they are first in the list), intersection is not
732 // strictly necessary, we simply copy the ranges and apply the delta
733 context->ranges = related_context->ranges;
734 /* Delta has already been checked for over/under-flow when evaluating values */
735 MONO_ADD_DELTA_SAFELY_TO_RANGES (context->ranges, relation->related_value.value.variable.delta);
736 context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
737 if (TRACE_ABC_REMOVAL) {
738 printf (", ranges already computed, result: \n");
739 print_evaluation_context_ranges (&(context->ranges));
740 printf (" (delta is %d)\n", relation->related_value.value.variable.delta);
743 // If it is not complete, do nothing (we do not have enough information)
744 if (TRACE_ABC_REMOVAL) {
745 printf (", ranges not computed\n");
749 // If we are not (the common case) intersect the result
750 intersect_ranges( &(context->ranges), &(related_context->ranges), relation->related_value.value.variable.delta, relation->relation );
753 if (TRACE_ABC_REMOVAL) {
754 printf ("Relation is a back-edge in this traversal, skipping\n");
759 case MONO_PHI_SUMMARIZED_VALUE: {
760 // We must compute all PHI alternatives, combining the results (with a union, which is a logical "or"),
761 // and intersect this result with the ranges in the context; we must also take into account recursions
762 // (with loops that can be ascending, descending, or indefinite)
763 MonoRelationsEvaluationRanges phi_ranges;
765 gboolean is_ascending = FALSE;
766 gboolean is_descending = FALSE;
768 MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (phi_ranges);
769 for (phi = 0; phi < relation->related_value.value.phi.number_of_alternatives; phi++) {
770 int phi_alternative = relation->related_value.value.phi.phi_alternatives [phi];
771 evaluate_relation_with_target_variable (area, phi_alternative, target_variable, context);
773 // This means we are part of a recursive loop
774 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
775 if (TRACE_ABC_REMOVAL) {
776 printf ("Recursivity detected for variable %d (target variable %d), status ", variable, target_variable);
777 print_evaluation_context_status (context->status);
780 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
783 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
784 is_descending = TRUE;
786 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
788 is_descending = TRUE;
791 // Clear "recursivity" bits in the status (recursion has been handled)
792 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
794 MONO_RELATIONS_EVALUATION_RANGES_UNION (phi_ranges, area->contexts [phi_alternative].ranges);
798 // Apply the effects of all recursive loops
800 phi_ranges.zero.upper = INT_MAX;
801 phi_ranges.variable.upper = INT_MAX;
804 phi_ranges.zero.lower = INT_MIN;
805 phi_ranges.variable.lower = INT_MIN;
808 // Intersect final result
809 MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (context->ranges, phi_ranges);
813 g_assert_not_reached();
816 // Pass to next relation
817 relation = relation->next;
820 // Check if any recursivity bits are still in the status, and in any case clear them
821 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
822 if (TRACE_ABC_REMOVAL) {
823 printf ("Recursivity for variable %d (target variable %d) discards computation, status ", variable, target_variable);
824 print_evaluation_context_status (context->status);
827 // If yes, we did not have enough information (most likely we were evaluated inside a PHI, but we also
828 // depended on the same PHI, which was still in evaluation...), so clear the status to "NOT_STARTED"
829 // (if we will be evaluated again, the PHI will be already done, so our evaluation will succeed)
830 context->status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
832 if (TRACE_ABC_REMOVAL) {
833 printf ("Ranges for variable %d (target variable %d) computed: ", variable, target_variable);
834 print_evaluation_context_ranges (&(context->ranges));
837 // If not (the common case) the evaluation is complete, and the result is in the context
838 context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
842 case MONO_RELATIONS_EVALUATION_IN_PROGRESS: {
843 // This means we are in a recursive loop
844 MonoRelationsEvaluationContext *current_context = father_context;
845 MonoRelationsEvaluationContext *last_context = context->father;
846 gboolean evaluation_can_be_recursive = TRUE;
847 gboolean evaluation_is_definition = TRUE;
850 if (TRACE_ABC_REMOVAL) {
851 printf ("Evaluation of variable %d (target variable %d) already in progress\n", variable, target_variable);
852 print_evaluation_context (context);
853 print_summarized_value_relation (context->current_relation);
857 // We must check if the loop can be a recursive definition (we scan the whole loop)
858 while (current_context != last_context) {
859 if (current_context == NULL) {
860 printf ("Broken recursive ring in ABC removal\n");
861 g_assert_not_reached ();
864 if (current_context->current_relation->relation_is_static_definition) {
865 if (current_context->current_relation->related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
866 /* No need to check path_value for over/under-flow, since delta should be safe */
867 path_value += current_context->current_relation->related_value.value.variable.delta;
868 } else if (current_context->current_relation->related_value.type != MONO_PHI_SUMMARIZED_VALUE) {
869 evaluation_can_be_recursive = FALSE;
872 evaluation_is_definition = FALSE;
873 evaluation_can_be_recursive = FALSE;
876 current_context = current_context->father;
879 // If this is a recursive definition, we properly flag the status in all the involved contexts
880 if (evaluation_is_definition) {
881 MonoRelationsEvaluationStatus recursive_status;
882 if (evaluation_can_be_recursive) {
883 if (path_value > 0) {
884 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING;
885 } else if (path_value < 0) {
886 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING;
888 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
891 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
894 if (TRACE_ABC_REMOVAL) {
895 printf ("Recursivity accepted (");
896 print_evaluation_context_status (recursive_status);
900 current_context = father_context;
901 while (current_context != last_context) {
902 current_context->status |= recursive_status;
903 current_context = current_context->father;
906 if (TRACE_ABC_REMOVAL) {
907 printf ("Recursivity rejected (some relation in the cycle is not a defintion)\n");
912 case MONO_RELATIONS_EVALUATION_COMPLETED: {
916 if (TRACE_ABC_REMOVAL) {
917 printf ("Variable %d (target variable %d) already in a recursive ring, skipping\n", variable, target_variable);
918 print_evaluation_context (context);
919 print_summarized_value_relation (context->current_relation);
928 * Apply the given value kind to the given range
931 apply_value_kind_to_range (MonoRelationsEvaluationRange *range, MonoIntegerValueKind value_kind)
933 if (value_kind != MONO_UNKNOWN_INTEGER_VALUE) {
934 if (value_kind & MONO_UNSIGNED_VALUE_FLAG) {
935 if (range->lower < 0) {
938 if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
939 if (range->upper > 0xff) {
942 } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
943 if (range->upper > 0xffff) {
944 range->upper = 0xffff;
948 if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
949 if (range->lower < -0x80) {
950 range->lower = -0x80;
952 if (range->upper > 0x7f) {
955 } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
956 if (range->lower < -0x8000) {
957 range->lower = -0x8000;
959 if (range->upper > 0x7fff) {
960 range->upper = 0x7fff;
968 * Attempt the removal of bounds checks from a MonoInst.
970 * area: the current evaluation area (it contains the relation graph and
971 * memory for all the evaluation contexts is already allocated)
974 remove_abc_from_inst (MonoInst *ins, MonoVariableRelationsEvaluationArea *area)
976 /* FIXME: Add support for 'constant' arrays and constant indexes */
978 int array_variable = ins->sreg1;
979 int index_variable = ins->sreg2;
980 MonoRelationsEvaluationContext *array_context = &(area->contexts [array_variable]);
981 MonoRelationsEvaluationContext *index_context = &(area->contexts [index_variable]);
983 clean_contexts (area->contexts, area->cfg->next_vreg);
985 evaluate_relation_with_target_variable (area, index_variable, array_variable, NULL);
986 evaluate_relation_with_target_variable (area, array_variable, array_variable, NULL);
988 if ((index_context->ranges.zero.lower >=0) && ((index_context->ranges.variable.upper < 0)||(index_context->ranges.zero.upper < array_context->ranges.zero.lower))) {
989 if (REPORT_ABC_REMOVAL) {
990 printf ("ARRAY-ACCESS: removed bounds check on array %d with index %d\n",
991 array_variable, index_variable);
995 if (TRACE_ABC_REMOVAL) {
996 if (index_context->ranges.zero.lower >= 0) {
997 printf ("ARRAY-ACCESS: Removed lower bound check on array %d with index %d\n", array_variable, index_variable);
999 if (index_context->ranges.variable.upper < 0) {
1000 printf ("ARRAY-ACCESS: Removed upper bound check (through variable) on array %d with index %d\n", array_variable, index_variable);
1002 if (index_context->ranges.zero.upper < array_context->ranges.zero.lower) {
1003 printf ("ARRAY-ACCESS: Removed upper bound check (through constant) on array %d with index %d\n", array_variable, index_variable);
1010 eval_non_null (MonoVariableRelationsEvaluationArea *area, int reg)
1012 MonoRelationsEvaluationContext *context = &(area->contexts [reg]);
1014 clean_contexts (area->contexts, area->cfg->next_vreg);
1015 evaluate_relation_with_target_variable (area, reg, reg, NULL);
1017 return context->ranges.zero.lower > 0;
1021 add_non_null (MonoVariableRelationsEvaluationArea *area, MonoCompile *cfg, int reg,
1022 GSList **check_relations)
1024 MonoAdditionalVariableRelation *rel;
1026 rel = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoAdditionalVariableRelation));
1027 rel->variable = reg;
1028 rel->relation.relation = MONO_GT_RELATION;
1029 rel->relation.related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1030 rel->relation.related_value.value.constant.value = 0;
1032 apply_change_to_evaluation_area (area, rel);
1034 *check_relations = g_slist_append_mempool (cfg->mempool, *check_relations, rel);
1038 * Process a BB removing bounds checks from array accesses.
1039 * It does the following (in sequence):
1040 * - Get the BB entry condition
1041 * - Add its relations to the relation graph in the evaluation area
1042 * - Process all the MonoInst trees in the BB
1043 * - Recursively process all the children BBs in the dominator tree
1044 * - Remove the relations previously added to the relation graph
1046 * bb: the BB that must be processed
1047 * area: the current evaluation area (it contains the relation graph and
1048 * memory for all the evaluation contexts is already allocated)
1051 process_block (MonoCompile *cfg, MonoBasicBlock *bb, MonoVariableRelationsEvaluationArea *area) {
1054 MonoAdditionalVariableRelationsForBB additional_relations;
1055 GSList *dominated_bb, *l;
1056 GSList *check_relations = NULL;
1058 if (TRACE_ABC_REMOVAL) {
1059 printf ("\nProcessing block %d [dfn %d]...\n", bb->block_num, bb->dfn);
1062 if (bb->region != -1)
1065 get_relations_from_previous_bb (area, bb, &additional_relations);
1066 if (TRACE_ABC_REMOVAL) {
1067 if (additional_relations.relation1.relation.relation != MONO_ANY_RELATION) {
1068 printf ("Adding relation 1 on variable %d: ", additional_relations.relation1.variable);
1069 print_summarized_value_relation (&(additional_relations.relation1.relation));
1072 if (additional_relations.relation2.relation.relation != MONO_ANY_RELATION) {
1073 printf ("Adding relation 2 on variable %d: ", additional_relations.relation2.variable);
1074 print_summarized_value_relation (&(additional_relations.relation2.relation));
1078 apply_change_to_evaluation_area (area, &(additional_relations.relation1));
1079 apply_change_to_evaluation_area (area, &(additional_relations.relation2));
1082 for (ins = bb->code; ins; ins = ins->next) {
1083 MonoAdditionalVariableRelation *rel;
1084 int array_var, index_var;
1086 if (TRACE_ABC_REMOVAL) {
1087 printf ("Processing instruction %d\n", inst_index);
1091 if (ins->opcode == OP_BOUNDS_CHECK) { /* Handle OP_LDELEMA2D, too */
1092 if (TRACE_ABC_REMOVAL) {
1093 printf ("Attempting check removal...\n");
1096 array_var = ins->sreg1;
1097 index_var = ins->sreg2;
1099 remove_abc_from_inst (ins, area);
1101 /* We can derive additional relations from the bounds check */
1102 if (ins->opcode != OP_NOP) {
1103 rel = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoAdditionalVariableRelation));
1104 rel->variable = index_var;
1105 rel->relation.relation = MONO_LT_RELATION;
1106 rel->relation.related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
1107 rel->relation.related_value.value.variable.variable = array_var;
1108 rel->relation.related_value.value.variable.delta = 0;
1110 apply_change_to_evaluation_area (area, rel);
1112 check_relations = g_slist_append_mempool (cfg->mempool, check_relations, rel);
1114 rel = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoAdditionalVariableRelation));
1115 rel->variable = index_var;
1116 rel->relation.relation = MONO_GE_RELATION;
1117 rel->relation.related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1118 rel->relation.related_value.value.constant.value = 0;
1120 apply_change_to_evaluation_area (area, rel);
1122 check_relations = g_slist_append_mempool (cfg->mempool, check_relations, rel);
1126 if (ins->opcode == OP_CHECK_THIS) {
1127 if (eval_non_null (area, ins->sreg1)) {
1128 if (REPORT_ABC_REMOVAL)
1129 printf ("ARRAY-ACCESS: removed check_this instruction.\n");
1134 if (ins->opcode == OP_NOT_NULL)
1135 add_non_null (area, cfg, ins->sreg1, &check_relations);
1138 * FIXME: abcrem equates an array with its length,
1139 * so a = new int [100] implies a != null, but a = new int [0] doesn't.
1142 * Eliminate MONO_INST_FAULT flags if possible.
1144 if (COMPILE_LLVM (cfg) && (ins->opcode == OP_LDLEN ||
1145 ins->opcode == OP_BOUNDS_CHECK ||
1146 ins->opcode == OP_STRLEN ||
1147 (MONO_IS_LOAD_MEMBASE (ins) && (ins->flags & MONO_INST_FAULT)) ||
1148 (MONO_IS_STORE_MEMBASE (ins) && (ins->flags & MONO_INST_FAULT)))) {
1151 if (MONO_IS_STORE_MEMBASE (ins))
1152 reg = ins->inst_destbasereg;
1153 else if (MONO_IS_LOAD_MEMBASE (ins))
1154 reg = ins->inst_basereg;
1159 * This doesn't work because LLVM can move the non-faulting loads before the faulting
1160 * ones (test_0_llvm_moving_faulting_loads ()).
1161 * So only do it if we know the load cannot be moved before the instruction which ensures it is not
1162 * null (i.e. the def of its sreg).
1164 if (area->defs [reg] && area->defs [reg]->opcode == OP_NEWARR) {
1165 if (REPORT_ABC_REMOVAL)
1166 printf ("ARRAY-ACCESS: removed MONO_INST_FAULT flag.\n");
1167 ins->flags &= ~MONO_INST_FAULT;
1170 if (eval_non_null (area, reg)) {
1171 if (REPORT_ABC_REMOVAL)
1172 printf ("ARRAY-ACCESS: removed MONO_INST_FAULT flag.\n");
1173 ins->flags &= ~MONO_INST_FAULT;
1175 add_non_null (area, cfg, reg, &check_relations);
1181 if (TRACE_ABC_REMOVAL) {
1182 printf ("Processing block %d [dfn %d] done.\n", bb->block_num, bb->dfn);
1185 for (dominated_bb = bb->dominated; dominated_bb != NULL; dominated_bb = dominated_bb->next) {
1186 process_block (cfg, (MonoBasicBlock*) (dominated_bb->data), area);
1189 for (l = check_relations; l; l = l->next)
1190 remove_change_from_evaluation_area (l->data);
1192 remove_change_from_evaluation_area (&(additional_relations.relation1));
1193 remove_change_from_evaluation_area (&(additional_relations.relation2));
1196 static MonoIntegerValueKind
1197 type_to_value_kind (MonoType *type)
1200 return MONO_UNKNOWN_INTEGER_VALUE;
1201 switch (type->type) {
1203 return MONO_INTEGER_VALUE_SIZE_1;
1206 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
1209 return MONO_INTEGER_VALUE_SIZE_2;
1212 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
1215 return MONO_INTEGER_VALUE_SIZE_4;
1218 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
1221 return SIZEOF_VOID_P;
1224 return (MONO_UNSIGNED_VALUE_FLAG|SIZEOF_VOID_P);
1227 return MONO_INTEGER_VALUE_SIZE_8;
1230 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_8;
1232 return MONO_UNKNOWN_INTEGER_VALUE;
1237 * mono_perform_abc_removal:
1238 * @cfg: Control Flow Graph
1240 * Performs the ABC removal from a cfg in SSA form.
1241 * It does the following:
1242 * - Prepare the evaluation area
1243 * - Allocate memory for the relation graph in the evaluation area
1244 * (of course, only for variable definitions) and summarize there all
1245 * variable definitions
1246 * - Allocate memory for the evaluation contexts in the evaluation area
1247 * - Recursively process all the BBs in the dominator tree (it is enough
1248 * to invoke the processing on the entry BB)
1250 * cfg: the method code
1253 mono_perform_abc_removal (MonoCompile *cfg)
1255 MonoVariableRelationsEvaluationArea area;
1259 verbose_level = cfg->verbose_level;
1261 if (TRACE_ABC_REMOVAL) {
1262 printf ("\nRemoving array bound checks in %s\n", mono_method_full_name (cfg->method, TRUE));
1266 area.relations = (MonoSummarizedValueRelation *)
1267 mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation) * (cfg->next_vreg) * 2);
1268 area.contexts = (MonoRelationsEvaluationContext *)
1269 mono_mempool_alloc (cfg->mempool, sizeof (MonoRelationsEvaluationContext) * (cfg->next_vreg));
1270 area.variable_value_kind = (MonoIntegerValueKind *)
1271 mono_mempool_alloc (cfg->mempool, sizeof (MonoIntegerValueKind) * (cfg->next_vreg));
1272 area.defs = mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * cfg->next_vreg);
1273 for (i = 0; i < cfg->next_vreg; i++) {
1274 area.variable_value_kind [i] = MONO_UNKNOWN_INTEGER_VALUE;
1275 area.relations [i].relation = MONO_EQ_RELATION;
1276 area.relations [i].relation_is_static_definition = TRUE;
1277 MAKE_VALUE_ANY (area.relations [i].related_value);
1278 area.relations [i].next = NULL;
1279 area.defs [i] = NULL;
1282 for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
1285 if (TRACE_ABC_REMOVAL)
1286 printf ("\nABCREM BLOCK %d:\n", bb->block_num);
1288 for (ins = bb->code; ins; ins = ins->next) {
1289 const char *spec = INS_INFO (ins->opcode);
1291 if (spec [MONO_INST_DEST] == ' ' || MONO_IS_STORE_MEMBASE (ins))
1294 if (spec [MONO_INST_DEST] == 'i') {
1295 MonoIntegerValueKind effective_value_kind;
1296 MonoRelationsEvaluationRange range;
1297 MonoSummarizedValueRelation *type_relation;
1300 if (TRACE_ABC_REMOVAL)
1301 mono_print_ins (ins);
1303 var = get_vreg_to_inst (cfg, ins->dreg);
1305 area.variable_value_kind [ins->dreg] = type_to_value_kind (var->inst_vtype);
1307 effective_value_kind = get_relation_from_ins (&area, ins, &area.relations [ins->dreg], area.variable_value_kind [ins->dreg]);
1309 MONO_MAKE_RELATIONS_EVALUATION_RANGE_WEAK (range);
1310 apply_value_kind_to_range (&range, area.variable_value_kind [ins->dreg]);
1311 apply_value_kind_to_range (&range, effective_value_kind);
1313 if (range.upper < INT_MAX) {
1314 type_relation = (MonoSummarizedValueRelation *) mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation));
1315 type_relation->relation = MONO_LE_RELATION;
1316 type_relation->related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1317 type_relation->related_value.value.constant.value = range.upper;
1318 type_relation->relation_is_static_definition = TRUE;
1319 type_relation->next = area.relations [ins->dreg].next;
1320 area.relations [ins->dreg].next = type_relation;
1321 if (TRACE_ABC_REMOVAL) {
1322 printf ("[var%d <= %d]", ins->dreg, range.upper);
1325 if (range.lower > INT_MIN) {
1326 type_relation = (MonoSummarizedValueRelation *) mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation));
1327 type_relation->relation = MONO_GE_RELATION;
1328 type_relation->related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1329 type_relation->related_value.value.constant.value = range.lower;
1330 type_relation->relation_is_static_definition = TRUE;
1331 type_relation->next = area.relations [ins->dreg].next;
1332 area.relations [ins->dreg].next = type_relation;
1333 if (TRACE_ABC_REMOVAL) {
1334 printf ("[var%d >= %d]", ins->dreg, range.lower);
1337 if (TRACE_ABC_REMOVAL) {
1338 printf ("Summarized variable %d: ", ins->dreg);
1339 print_summarized_value (&(area.relations [ins->dreg].related_value));
1346 /* Add symmetric relations */
1347 for (i = 0; i < cfg->next_vreg; i++) {
1348 if (area.relations [i].related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1349 int related_index = cfg->next_vreg + i;
1350 int related_variable = area.relations [i].related_value.value.variable.variable;
1352 area.relations [related_index].relation = MONO_EQ_RELATION;
1353 area.relations [related_index].relation_is_static_definition = TRUE;
1354 area.relations [related_index].related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
1355 area.relations [related_index].related_value.value.variable.variable = i;
1356 area.relations [related_index].related_value.value.variable.delta = - area.relations [i].related_value.value.variable.delta;
1358 area.relations [related_index].next = area.relations [related_variable].next;
1359 area.relations [related_variable].next = &(area.relations [related_index]);
1361 if (TRACE_ABC_REMOVAL) {
1362 printf ("Added symmetric summarized value for variable variable %d (to %d): ", i, related_variable);
1363 print_summarized_value (&(area.relations [related_index].related_value));
1369 process_block (cfg, cfg->bblocks [0], &area);
1372 #endif /* DISABLE_JIT */