mono/mini/abcremoval.c

   1 /*
   2  * abcremoval.c: Array bounds check removal
   3  *
   4  * Author:
   5  *   Massimiliano Mantione (massi@ximian.com)
   6  *
   7  * (C) 2004 Ximian, Inc.  http://www.ximian.com
   8  */
   9 #include <string.h>
  10 #include <stdio.h>
  11
  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>
  16
  17 #include <config.h>
  18
  19 #ifndef DISABLE_JIT
  20
  21 #include "abcremoval.h"
  22
  23 #if SIZEOF_VOID_P == 8
  24 #define OP_PCONST OP_I8CONST
  25 #else
  26 #define OP_PCONST OP_ICONST
  27 #endif
  28
  29
  30 #define TRACE_ABC_REMOVAL (verbose_level > 2)
  31 #define REPORT_ABC_REMOVAL (verbose_level > 1)
  32
  33 /*
  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.
  43  */
  44 static int verbose_level;
  45
  46
  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))
  50
  51 #define MAKE_VALUE_ANY(v) do{\
  52                 (v).type = MONO_ANY_SUMMARIZED_VALUE;\
  53         } while (0)
  54
  55 #define MAKE_VALUE_RELATION_ANY(r) do{\
  56                 (r)->relation = MONO_ANY_RELATION;\
  57                 MAKE_VALUE_ANY((r)->related_value);\
  58         } while (0)
  59
  60 #define INITIALIZE_VALUE_RELATION(r) do{\
  61                 MAKE_VALUE_RELATION_ANY((r));\
  62                 (r)->next = NULL;\
  63         } while (0)
  64
  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))
  67
  68
  69
  70 static void
  71 print_relation (int relation) {
  72         int print_or = 0;
  73         printf ("(");
  74         if (relation & MONO_LT_RELATION) {
  75                 printf ("LT");
  76                 print_or = 1;
  77         }
  78         if (relation & MONO_EQ_RELATION) {
  79                 if (print_or) {
  80                         printf ("|");
  81                 }
  82                 printf ("EQ");
  83                 print_or = 1;
  84         }
  85         if (relation & MONO_GT_RELATION) {
  86                 if (print_or) {
  87                         printf ("|");
  88                 }
  89                 printf ("GT");
  90                 print_or = 1;
  91         }
  92         printf (")");
  93 }
  94
  95 static void
  96 print_summarized_value (MonoSummarizedValue *value) {
  97         switch (value->type) {
  98         case MONO_ANY_SUMMARIZED_VALUE:
  99                 printf ("ANY");
 100                 break;
 101         case MONO_CONSTANT_SUMMARIZED_VALUE:
 102                 printf ("CONSTANT %d", value->value.constant.value);
 103                 break;
 104         case MONO_VARIABLE_SUMMARIZED_VALUE:
 105                 printf ("VARIABLE %d, delta %d", value->value.variable.variable, value->value.variable.delta);
 106                 break;
 107         case MONO_PHI_SUMMARIZED_VALUE: {
 108                 int phi;
 109                 printf ("PHI (");
 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]);
 113                 }
 114                 printf (")");
 115                 break;
 116         }
 117         default:
 118                 g_assert_not_reached ();
 119         }
 120 }
 121
 122 static void
 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));
 128 }
 129
 130 #if 0
 131 static void
 132 print_summarized_value_relation_chain (MonoSummarizedValueRelation *relation) {
 133         printf ("Relations:\n");
 134         while (relation) {
 135                 print_summarized_value_relation (relation);
 136                 printf ("\n");
 137                 relation = relation->next;
 138         }
 139 }
 140 #endif
 141
 142 static void
 143 print_evaluation_context_status (MonoRelationsEvaluationStatus status) {
 144         if (status == MONO_RELATIONS_EVALUATION_NOT_STARTED) {
 145                 printf ("EVALUATION_NOT_STARTED");
 146         } else {
 147                 gboolean print_or = FALSE;
 148
 149                 printf ("(");
 150                 if (status & MONO_RELATIONS_EVALUATION_IN_PROGRESS) {
 151                         if (print_or) printf ("|");
 152                         printf ("EVALUATION_IN_PROGRESS");
 153                         print_or = TRUE;
 154                 }
 155                 if (status & MONO_RELATIONS_EVALUATION_COMPLETED) {
 156                         if (print_or) printf ("|");
 157                         printf ("EVALUATION_COMPLETED");
 158                         print_or = TRUE;
 159                 }
 160                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
 161                         if (print_or) printf ("|");
 162                         printf ("RECURSIVELY_ASCENDING");
 163                         print_or = TRUE;
 164                 }
 165                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
 166                         if (print_or) printf ("|");
 167                         printf ("RECURSIVELY_DESCENDING");
 168                         print_or = TRUE;
 169                 }
 170                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
 171                         if (print_or) printf ("|");
 172                         printf ("RECURSIVELY_INDEFINITE");
 173                         print_or = TRUE;
 174                 }
 175                 printf (")");
 176         }
 177 }
 178
 179
 180 static void
 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);
 183 }
 184
 185 static void
 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));
 191         }
 192         printf ("\n");
 193 }
 194
 195 #if 0
 196 static void
 197 print_evaluation_area (MonoVariableRelationsEvaluationArea *area) {
 198         int i;
 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]));
 204         }
 205 }
 206
 207 static void
 208 print_evaluation_area_contexts (MonoVariableRelationsEvaluationArea *area) {
 209         int i;
 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]));
 214         }
 215 }
 216 #endif
 217
 218 /*
 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".
 222  */
 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) {
 229                         if (delta < 0) {
 230                                 MAKE_VALUE_ANY (*value);
 231                         }
 232                 } else {
 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);
 237                         }
 238                 }
 239         }
 240 }
 241
 242 /*
 243  * get_relation_from_ins:
 244  *
 245  *   Obtain relations from a MonoInst.
 246  *
 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)
 250  */
 251 static MonoIntegerValueKind
 252 get_relation_from_ins (MonoVariableRelationsEvaluationArea *area, MonoInst *ins, MonoSummarizedValueRelation *result, MonoIntegerValueKind result_value_kind)
 253 {
 254         MonoIntegerValueKind value_kind;
 255         MonoSummarizedValue *value = &result->related_value;
 256
 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;
 261         } else {
 262                 value_kind = MONO_UNKNOWN_INTEGER_VALUE;
 263         }
 264
 265         result->relation = MONO_EQ_RELATION;
 266         MAKE_VALUE_ANY (*value);
 267
 268         switch (ins->opcode) {
 269         case OP_ICONST:
 270                 value->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 271                 value->value.constant.value = ins->inst_c0;
 272                 break;
 273         case OP_MOVE:
 274                 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 275                 value->value.variable.variable = ins->sreg1;
 276                 value->value.variable.delta = 0;
 277                 break;
 278         case OP_SEXT_I4:
 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;
 283                 break;
 284         case OP_PHI:
 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;
 288                 break;
 289         case OP_IADD_IMM:
 290                 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 291                 value->value.variable.variable = ins->sreg1;
 292                 value->value.variable.delta = ins->inst_imm;
 293                 /* FIXME: */
 294                 //check_delta_safety (area, result);
 295                 break;
 296         case OP_ISUB_IMM:
 297                 value->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 298                 value->value.variable.variable = ins->sreg1;
 299                 value->value.variable.delta = -ins->inst_imm;
 300                 /* FIXME: */
 301                 //check_delta_safety (area, result);
 302                 break;
 303         case OP_IREM_UN:
 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;
 310                 break;
 311         case OP_LDLEN:
 312                 /*
 313                  * We represent arrays by their length, so r1<-ldlen r2 is stored
 314                  * as r1 == r2 in the evaluation graph.
 315                  */
 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;
 320                 break;
 321         case OP_NEWARR:
 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;
 326                 break;
 327         case OP_LDADDR:
 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;
 332                 break;
 333
 334                 /* FIXME: Add more opcodes */
 335         default:
 336                 /* These opcodes are not currently handled while running SciMark, first
 337                  * column is the number of times the warning was shown:
 338                  *
 339                  *       1 add_imm
 340                  *       1 float_conv_to_i8
 341                  *       1 int_mul_ovf_un
 342                  *       1 int_neg
 343                  *       1 int_or
 344                  *       1 int_shr_un
 345                  *       1 localloc
 346                  *       1 long_ceq
 347                  *       1 long_rem
 348                  *       1 long_sub
 349                  *       2 int_ceq
 350                  *       2 int_conv_to_i2
 351                  *       2 int_min
 352                  *       2 lcall
 353                  *       2 long_div
 354                  *       3 int_conv_to_u2
 355                  *       3 long_shr_imm
 356                  *       4 int_rem
 357                  *       4 int_rem_imm
 358                  *       4 loadi1_membase
 359                  *       4 loadu4_membase
 360                  *       5 int_div
 361                  *       5 shl_imm
 362                  *       6 int_div_imm
 363                  *       6 int_mul
 364                  *       9 int_mul_imm
 365                  *       9 zext_i4
 366                  *      10 int_shr_imm
 367                  *      12 int_shr_un_imm
 368                  *      12 long_add_imm
 369                  *      12 outarg_vtretaddr
 370                  *      12 strlen
 371                  *      13 int_or_imm
 372                  *      23 call_membase
 373                  *      23 int_conv_to_u1
 374                  *      23 long_add
 375                  *      24 int_and_imm
 376                  *      24 int_shl_imm
 377                  *      24 loadu2_membase
 378                  *      29 loadi8_membase
 379                  *      31 llvm_outarg_vt
 380                  *      34 int_sub
 381                  *      34 loadu1_membase
 382                  *      42 int_add
 383                  *      85 ldaddr
 384                  *     116 loadi4_membase
 385                  *     159 x86_lea
 386                  *     179 sext_i4
 387                  *     291 load_membase
 388                  *     462 i8const
 389                  *     472 call
 390                  */
 391
 392                 break;
 393         }
 394         return value_kind;
 395 }
 396
 397 static MonoValueRelation
 398 get_relation_from_branch_instruction (MonoInst *ins)
 399 {
 400         if (MONO_IS_COND_BRANCH_OP (ins)) {
 401                 CompRelation rel = mono_opcode_to_cond (ins->opcode);
 402
 403                 switch (rel) {
 404                 case CMP_EQ:
 405                         return MONO_EQ_RELATION;
 406                 case CMP_NE:
 407                         return MONO_NE_RELATION;
 408                 case CMP_LE:
 409                 case CMP_LE_UN:
 410                         return MONO_LE_RELATION;
 411                 case CMP_GE:
 412                 case CMP_GE_UN:
 413                         return MONO_GE_RELATION;
 414                 case CMP_LT:
 415                 case CMP_LT_UN:
 416                         return MONO_LT_RELATION;
 417                 case CMP_GT:
 418                 case CMP_GT_UN:
 419                         return MONO_GT_RELATION;
 420                 default:
 421                         g_assert_not_reached ();
 422                         return MONO_ANY_RELATION;
 423                 }
 424         } else {
 425                 return MONO_ANY_RELATION;
 426         }
 427 }
 428
 429 /*
 430  * Given a BB, find its entry condition and put its relations in a
 431  * "MonoAdditionalVariableRelationsForBB" structure.
 432  * bb: the BB
 433  * relations: the resulting relations (entry condition of the given BB)
 434  */
 435 static void
 436 get_relations_from_previous_bb (MonoVariableRelationsEvaluationArea *area, MonoBasicBlock *bb, MonoAdditionalVariableRelationsForBB *relations)
 437 {
 438         MonoBasicBlock *in_bb;
 439         MonoInst *ins, *compare, *branch;
 440         MonoValueRelation branch_relation;
 441         MonoValueRelation symmetric_relation;
 442         gboolean code_path;
 443
 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;
 454
 455         if (bb->in_count == 1) { /* Should write the code to "sum" conditions... */
 456                 in_bb = bb->in_bb [0];
 457
 458                 if ((in_bb->last_ins == NULL) || (in_bb->code == in_bb->last_ins))
 459                         return;
 460
 461                 for (ins = in_bb->code; ins->next != in_bb->last_ins; ins = ins->next)
 462                         ;
 463
 464                 compare = ins;
 465                 branch = ins->next;
 466                 branch_relation = get_relation_from_branch_instruction (branch);
 467
 468                 if (branch_relation != MONO_ANY_RELATION) {
 469                         if (branch->inst_true_bb == bb) {
 470                                 code_path = TRUE;
 471                         } else if (branch->inst_false_bb == bb) {
 472                                 code_path = FALSE;
 473                         } else {
 474                                 code_path = TRUE;
 475                                 g_assert_not_reached ();
 476                         }
 477                         if (!code_path)
 478                                 branch_relation = MONO_NEGATED_RELATION (branch_relation);
 479                         symmetric_relation = MONO_SYMMETRIC_RELATION (branch_relation);
 480
 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;
 488
 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;
 499                         }
 500                 }
 501         }
 502 }
 503
 504 /*
 505  * Add the given relations to the evaluation area.
 506  * area: the evaluation area
 507  * change: the relations that must be added
 508  */
 509 static void
 510 apply_change_to_evaluation_area (MonoVariableRelationsEvaluationArea *area, MonoAdditionalVariableRelation *change)
 511 {
 512         MonoSummarizedValueRelation *base_relation;
 513
 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;
 518                 }
 519                 change->insertion_point = base_relation;
 520                 change->relation.next = base_relation->next;
 521                 base_relation->next = &(change->relation);
 522         }
 523 }
 524
 525 /*
 526  * Remove the given relation from the evaluation area.
 527  * change: the relation that must be removed
 528  */
 529 static void
 530 remove_change_from_evaluation_area (MonoAdditionalVariableRelation *change)
 531 {
 532         if (change->insertion_point != NULL) {
 533                 change->insertion_point->next = change->relation.next;
 534                 change->relation.next = NULL;
 535         }
 536 }
 537
 538
 539 static void
 540 clean_contexts (MonoRelationsEvaluationContext *contexts, int number)
 541 {
 542         int i;
 543         for (i = 0; i < number; i++) {
 544                 contexts [i].status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
 545         }
 546 }
 547
 548
 549 /*
 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
 555  */
 556 static void
 557 intersect_value( MonoRelationsEvaluationRange *range, int value, MonoValueRelation relation )
 558 {
 559         switch (relation) {
 560         case MONO_NO_RELATION:
 561                 MONO_MAKE_RELATIONS_EVALUATION_RANGE_IMPOSSIBLE (*range);
 562                 break;
 563         case MONO_ANY_RELATION:
 564                 break;
 565         case MONO_EQ_RELATION:
 566                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
 567                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
 568                 break;
 569         case MONO_NE_RELATION: {
 570                 /* IMPROVEMENT Figure this out! (ignoring it is safe anyway) */
 571                 break;
 572         }
 573         case MONO_LT_RELATION:
 574                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (value));
 575                 break;
 576         case MONO_LE_RELATION:
 577                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
 578                 break;
 579         case MONO_GT_RELATION:
 580                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (value));
 581                 break;
 582         case MONO_GE_RELATION:
 583                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
 584                 break;
 585         default:
 586                 g_assert_not_reached();
 587         }
 588 }
 589
 590
 591 /*
 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
 598  */
 599 static void
 600 intersect_ranges( MonoRelationsEvaluationRanges *ranges, MonoRelationsEvaluationRanges *other_ranges, int delta, MonoValueRelation relation )
 601 {
 602         if (delta == 0) {
 603                 switch (relation) {
 604                 case MONO_NO_RELATION:
 605                         MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (*ranges);
 606                         break;
 607                 case MONO_ANY_RELATION:
 608                         break;
 609                 case MONO_EQ_RELATION:
 610                         MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (*ranges, *other_ranges);
 611                         break;
 612                 case MONO_NE_RELATION: {
 613                         /* FIXME Figure this out! (ignoring it is safe anyway) */
 614                         break;
 615                 }
 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));
 619                         break;
 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);
 623                         break;
 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));
 627                         break;
 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);
 631                         break;
 632                 default:
 633                         g_assert_not_reached();
 634                 }
 635         } else {
 636                 MonoRelationsEvaluationRanges translated_ranges = *other_ranges;
 637                 MONO_ADD_DELTA_SAFELY_TO_RANGES (translated_ranges, delta);
 638                 intersect_ranges( ranges, &translated_ranges, FALSE, relation );
 639         }
 640 }
 641
 642 /*
 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)
 656  */
 657 static void
 658 evaluate_relation_with_target_variable (MonoVariableRelationsEvaluationArea *area, int variable, int target_variable, MonoRelationsEvaluationContext *father_context)
 659 {
 660         MonoRelationsEvaluationContext *context = &(area->contexts [variable]);
 661
 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]);
 667
 668                 if (TRACE_ABC_REMOVAL) {
 669                         printf ("Evaluating variable %d (target variable %d)\n", variable, target_variable);
 670                         print_summarized_value_relation (relation);
 671                         printf ("\n");
 672                 }
 673
 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);
 678
 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);
 684                         }
 685                         context->ranges.variable.lower = 0;
 686                         context->ranges.variable.upper = 0;
 687                 }
 688
 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;
 693
 694                         if (TRACE_ABC_REMOVAL) {
 695                                 printf ("Processing (%d): ", variable);
 696                                 print_summarized_value_relation (relation);
 697                                 printf ("\n");
 698                         }
 699
 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
 704                                 break;
 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);
 708                                 break;
 709                         case MONO_VARIABLE_SUMMARIZED_VALUE:
 710                                 // Generally, evaluate related variable and intersect ranges.
 711                                 // However, some check is necessary...
 712
 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]);
 717
 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);
 725
 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);
 731                                                         }
 732
 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);
 747                                                                 }
 748                                                         } else {
 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");
 752                                                                 }
 753                                                         }
 754                                                 } else {
 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 );
 757                                                 }
 758                                         } else {
 759                                                 if (TRACE_ABC_REMOVAL) {
 760                                                         printf ("Relation is a back-edge in this traversal, skipping\n");
 761                                                 }
 762                                         }
 763                                 }
 764                                 break;
 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;
 770                                 int phi;
 771                                 gboolean is_ascending = FALSE;
 772                                 gboolean is_descending = FALSE;
 773
 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);
 778
 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);
 784                                                         printf ("\n");
 785                                                 }
 786                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
 787                                                         is_ascending = TRUE;
 788                                                 }
 789                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
 790                                                         is_descending = TRUE;
 791                                                 }
 792                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
 793                                                         is_ascending = TRUE;
 794                                                         is_descending = TRUE;
 795                                                 }
 796
 797                                                 // Clear "recursivity" bits in the status (recursion has been handled)
 798                                                 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
 799                                         } else {
 800                                                 MONO_RELATIONS_EVALUATION_RANGES_UNION (phi_ranges, area->contexts [phi_alternative].ranges);
 801                                         }
 802                                 }
 803
 804                                 // Apply the effects of all recursive loops
 805                                 if (is_ascending) {
 806                                         phi_ranges.zero.upper = INT_MAX;
 807                                         phi_ranges.variable.upper = INT_MAX;
 808                                 }
 809                                 if (is_descending) {
 810                                         phi_ranges.zero.lower = INT_MIN;
 811                                         phi_ranges.variable.lower = INT_MIN;
 812                                 }
 813
 814                                 // Intersect final result
 815                                 MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (context->ranges, phi_ranges);
 816                                 break;
 817                         }
 818                         default:
 819                                 g_assert_not_reached();
 820                         }
 821
 822                         // Pass to next relation
 823                         relation = relation->next;
 824                 }
 825
 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);
 831                                 printf ("\n");
 832                         }
 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;
 837                 } else {
 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));
 841                                 printf ("\n");
 842                         }
 843                         // If not (the common case) the evaluation is complete, and the result is in the context
 844                         context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
 845                 }
 846                 break;
 847         }
 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;
 854                 int path_value = 0;
 855
 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);
 860                         printf ("\n");
 861                 }
 862
 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 ();
 868                         }
 869
 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;
 876                                 }
 877                         } else {
 878                                 evaluation_is_definition = FALSE;
 879                                 evaluation_can_be_recursive = FALSE;
 880                         }
 881
 882                         current_context = current_context->father;
 883                 }
 884
 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;
 893                                 } else {
 894                                         recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
 895                                 }
 896                         } else {
 897                                 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
 898                         }
 899
 900                         if (TRACE_ABC_REMOVAL) {
 901                                 printf ("Recursivity accepted (");
 902                                 print_evaluation_context_status (recursive_status);
 903                                 printf (")\n");
 904                         }
 905
 906                         current_context = father_context;
 907                         while (current_context != last_context) {
 908                                 current_context->status |= recursive_status;
 909                                 current_context = current_context->father;
 910                         }
 911                 } else {
 912                         if (TRACE_ABC_REMOVAL) {
 913                                 printf ("Recursivity rejected (some relation in the cycle is not a defintion)\n");
 914                         }
 915                 }
 916                 break;
 917         }
 918         case MONO_RELATIONS_EVALUATION_COMPLETED: {
 919                 return;
 920         }
 921         default:
 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);
 926                         printf ("\n");
 927                 }
 928                 break;
 929         }
 930
 931 }
 932
 933 /*
 934  * Apply the given value kind to the given range
 935  */
 936 static void
 937 apply_value_kind_to_range (MonoRelationsEvaluationRange *range, MonoIntegerValueKind value_kind)
 938 {
 939         if (value_kind != MONO_UNKNOWN_INTEGER_VALUE) {
 940                 if (value_kind & MONO_UNSIGNED_VALUE_FLAG) {
 941                         if (range->lower < 0) {
 942                                 range->lower = 0;
 943                         }
 944                         if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
 945                                 if (range->upper > 0xff) {
 946                                         range->upper = 0xff;
 947                                 }
 948                         } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
 949                                 if (range->upper > 0xffff) {
 950                                         range->upper = 0xffff;
 951                                 }
 952                         }
 953                 } else {
 954                         if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
 955                                 if (range->lower < -0x80) {
 956                                         range->lower = -0x80;
 957                                 }
 958                                 if (range->upper > 0x7f) {
 959                                         range->upper = 0x7f;
 960                                 }
 961                         } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
 962                                 if (range->lower < -0x8000) {
 963                                         range->lower = -0x8000;
 964                                 }
 965                                 if (range->upper > 0x7fff) {
 966                                         range->upper = 0x7fff;
 967                                 }
 968                         }
 969                 }
 970         }
 971 }
 972
 973 /*
 974  * Attempt the removal of bounds checks from a MonoInst.
 975  * inst: the MonoInst
 976  * area: the current evaluation area (it contains the relation graph and
 977  *       memory for all the evaluation contexts is already allocated)
 978  */
 979 static void
 980 remove_abc_from_inst (MonoInst *ins, MonoVariableRelationsEvaluationArea *area)
 981 {
 982         /* FIXME: Add support for 'constant' arrays and constant indexes */
 983
 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]);
 988
 989         clean_contexts (area->contexts, area->cfg->next_vreg);
 990
 991         evaluate_relation_with_target_variable (area, index_variable, array_variable, NULL);
 992         evaluate_relation_with_target_variable (area, array_variable, array_variable, NULL);
 993
 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);
 998                 }
 999                 NULLIFY_INS (ins);
1000         } else {
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);
1004                         }
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);
1007                         }
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);
1010                         }
1011                 }
1012         }
1013 }
1014
1015 static gboolean
1016 eval_non_null (MonoVariableRelationsEvaluationArea *area, int reg)
1017 {
1018         MonoRelationsEvaluationContext *context = &(area->contexts [reg]);
1019
1020         clean_contexts (area->contexts, area->cfg->next_vreg);
1021         evaluate_relation_with_target_variable (area, reg, reg, NULL);
1022
1023         return context->ranges.zero.lower > 0;
1024 }
1025
1026 static void
1027 add_non_null (MonoVariableRelationsEvaluationArea *area, MonoCompile *cfg, int reg,
1028                           GSList **check_relations)
1029 {
1030         MonoAdditionalVariableRelation *rel;
1031
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;
1037
1038         apply_change_to_evaluation_area (area, rel);
1039
1040         *check_relations = g_slist_append_mempool (cfg->mempool, *check_relations, rel);
1041 }
1042
1043 /*
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
1051  *
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)
1055  */
1056 static void
1057 process_block (MonoCompile *cfg, MonoBasicBlock *bb, MonoVariableRelationsEvaluationArea *area) {
1058         int inst_index;
1059         MonoInst *ins;
1060         MonoAdditionalVariableRelationsForBB additional_relations;
1061         GSList *dominated_bb, *l;
1062         GSList *check_relations = NULL;
1063
1064         if (TRACE_ABC_REMOVAL) {
1065                 printf ("\nProcessing block %d [dfn %d]...\n", bb->block_num, bb->dfn);
1066         }
1067
1068         if (bb->region != -1)
1069                 return;
1070
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));
1076                         printf ("\n");
1077                 }
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));
1081                         printf ("\n");
1082                 }
1083         }
1084         apply_change_to_evaluation_area (area, &(additional_relations.relation1));
1085         apply_change_to_evaluation_area (area, &(additional_relations.relation2));
1086
1087         inst_index = 0;
1088         for (ins = bb->code; ins; ins = ins->next) {
1089                 MonoAdditionalVariableRelation *rel;
1090                 int array_var, index_var;
1091
1092                 if (TRACE_ABC_REMOVAL) {
1093                         printf ("Processing instruction %d\n", inst_index);
1094                         inst_index++;
1095                 }
1096
1097                 if (ins->opcode == OP_BOUNDS_CHECK) { /* Handle OP_LDELEMA2D, too */
1098                         if (TRACE_ABC_REMOVAL) {
1099                                 printf ("Attempting check removal...\n");
1100                         }
1101
1102                         array_var = ins->sreg1;
1103                         index_var = ins->sreg2;
1104
1105                         remove_abc_from_inst (ins, area);
1106
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;
1115
1116                                 apply_change_to_evaluation_area (area, rel);
1117
1118                                 check_relations = g_slist_append_mempool (cfg->mempool, check_relations, rel);
1119
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;
1125
1126                                 apply_change_to_evaluation_area (area, rel);
1127
1128                                 check_relations = g_slist_append_mempool (cfg->mempool, check_relations, rel);
1129                         }
1130                 }
1131
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");
1136                                 NULLIFY_INS (ins);
1137                         }
1138                 }
1139
1140                 if (ins->opcode == OP_NOT_NULL)
1141                         add_non_null (area, cfg, ins->sreg1, &check_relations);
1142
1143                 /*
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.
1146                  */
1147                 /*
1148                  * Eliminate MONO_INST_FAULT flags if possible.
1149                  */
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)))) {
1155                         int reg;
1156
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;
1161                         else
1162                                 reg = ins->sreg1;
1163
1164                         /*
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).
1169                          */
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;
1174                         }
1175                         /*
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;
1180                         } else {
1181                                 add_non_null (area, cfg, reg, &check_relations);
1182                         }
1183                         */
1184                 }
1185         }
1186
1187         if (TRACE_ABC_REMOVAL) {
1188                 printf ("Processing block %d [dfn %d] done.\n", bb->block_num, bb->dfn);
1189         }
1190
1191         for (dominated_bb = bb->dominated; dominated_bb != NULL; dominated_bb = dominated_bb->next) {
1192                 process_block (cfg, (MonoBasicBlock*) (dominated_bb->data), area);
1193         }
1194
1195         for (l = check_relations; l; l = l->next)
1196                 remove_change_from_evaluation_area (l->data);
1197
1198         remove_change_from_evaluation_area (&(additional_relations.relation1));
1199         remove_change_from_evaluation_area (&(additional_relations.relation2));
1200 }
1201
1202 static MonoIntegerValueKind
1203 type_to_value_kind (MonoType *type)
1204 {
1205         if (type->byref)
1206                 return MONO_UNKNOWN_INTEGER_VALUE;
1207         switch (type->type) {
1208         case MONO_TYPE_I1:
1209                 return MONO_INTEGER_VALUE_SIZE_1;
1210                 break;
1211         case MONO_TYPE_U1:
1212                 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
1213                 break;
1214         case MONO_TYPE_I2:
1215                 return MONO_INTEGER_VALUE_SIZE_2;
1216                 break;
1217         case MONO_TYPE_U2:
1218                 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
1219                 break;
1220         case MONO_TYPE_I4:
1221                 return MONO_INTEGER_VALUE_SIZE_4;
1222                 break;
1223         case MONO_TYPE_U4:
1224                 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
1225                 break;
1226         case MONO_TYPE_I:
1227                 return SIZEOF_VOID_P;
1228                 break;
1229         case MONO_TYPE_U:
1230                 return (MONO_UNSIGNED_VALUE_FLAG|SIZEOF_VOID_P);
1231                 break;
1232         case MONO_TYPE_I8:
1233                 return MONO_INTEGER_VALUE_SIZE_8;
1234                 break;
1235         case MONO_TYPE_U8:
1236                 return MONO_UNSIGNED_INTEGER_VALUE_SIZE_8;
1237         default:
1238                 return MONO_UNKNOWN_INTEGER_VALUE;
1239         }
1240 }
1241
1242 /**
1243  * mono_perform_abc_removal:
1244  * @cfg: Control Flow Graph
1245  *
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)
1255  *
1256  * cfg: the method code
1257  */
1258 void
1259 mono_perform_abc_removal (MonoCompile *cfg)
1260 {
1261         MonoVariableRelationsEvaluationArea area;
1262         MonoBasicBlock *bb;
1263         int i;
1264
1265         verbose_level = cfg->verbose_level;
1266
1267         if (TRACE_ABC_REMOVAL) {
1268                 printf ("\nRemoving array bound checks in %s\n", mono_method_full_name (cfg->method, TRUE));
1269         }
1270
1271         area.cfg = cfg;
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;
1286         }
1287
1288         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
1289                 MonoInst *ins;
1290
1291                 if (TRACE_ABC_REMOVAL)
1292                         printf ("\nABCREM BLOCK %d:\n", bb->block_num);
1293
1294                 for (ins = bb->code; ins; ins = ins->next) {
1295                         const char *spec = INS_INFO (ins->opcode);
1296
1297                         if (spec [MONO_INST_DEST] == ' ' || MONO_IS_STORE_MEMBASE (ins))
1298                                 continue;
1299
1300                         if (spec [MONO_INST_DEST] == 'i') {
1301                                 MonoIntegerValueKind effective_value_kind;
1302                                 MonoRelationsEvaluationRange range;
1303                                 MonoSummarizedValueRelation *type_relation;
1304                                 MonoInst *var;
1305
1306                                 if (TRACE_ABC_REMOVAL)
1307                                         mono_print_ins (ins);
1308
1309                                 var = get_vreg_to_inst (cfg, ins->dreg);
1310                                 if (var)
1311                                         area.variable_value_kind [ins->dreg] = type_to_value_kind (var->inst_vtype);
1312
1313                                 effective_value_kind = get_relation_from_ins (&area, ins, &area.relations [ins->dreg], area.variable_value_kind [ins->dreg]);
1314
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);
1318
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);
1329                                         }
1330                                 }
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);
1341                                         }
1342                                 }
1343                                 if (TRACE_ABC_REMOVAL) {
1344                                         printf ("Summarized variable %d: ", ins->dreg);
1345                                         print_summarized_value (&(area.relations [ins->dreg].related_value));
1346                                         printf ("\n");
1347                                 }
1348                         }
1349                 }
1350         }
1351
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;
1357
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;
1363
1364                         area.relations [related_index].next = area.relations [related_variable].next;
1365                         area.relations [related_variable].next = &(area.relations [related_index]);
1366
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));
1370                                 printf ("\n");
1371                         }
1372                 }
1373         }
1374
1375         process_block (cfg, cfg->bblocks [0], &area);
1376 }
1377
1378 #endif /* DISABLE_JIT */