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
  16 #include "inssel.h"
  17
  18 #include "abcremoval.h"
  19
  20 #if SIZEOF_VOID_P == 8
  21 #define OP_PCONST OP_I8CONST
  22 #else
  23 #define OP_PCONST OP_ICONST
  24 #endif
  25
  26
  27 #define TRACE_ABC_REMOVAL (verbose_level > 2)
  28 #define REPORT_ABC_REMOVAL (verbose_level > 0)
  29
  30 /*
  31  * A little hack for the verbosity level.
  32  * The verbosity level is stored in the cfg, but not all functions that must
  33  * print something see the cfg, so we store the verbosity level here at the
  34  * beginning of the algorithm.
  35  * This is not thread safe (does not handle correctly different verbosity
  36  * levels in different threads), and is not exact in case of dynamic changes
  37  * of the verbosity level...
  38  * Anyway, this is not needed, all that can happen is that something more
  39  * (or less) is logged, the result is in any case correct.
  40  */
  41 static int verbose_level;
  42
  43
  44 #define RELATION_BETWEEN_VALUES(value,related_value) (\
  45         ((value) > (related_value))? MONO_GT_RELATION :\
  46         (((value) < (related_value))? MONO_LT_RELATION : MONO_EQ_RELATION))
  47
  48 #define MAKE_VALUE_ANY(v) do{\
  49                 (v).type = MONO_ANY_SUMMARIZED_VALUE;\
  50         } while (0)
  51
  52 #define MAKE_VALUE_RELATION_ANY(r) do{\
  53                 (r)->relation = MONO_ANY_RELATION;\
  54                 MAKE_VALUE_ANY((r)->related_value);\
  55         } while (0)
  56
  57 #define INITIALIZE_VALUE_RELATION(r) do{\
  58                 MAKE_VALUE_RELATION_ANY((r));\
  59                 (r)->next = NULL;\
  60         } while (0)
  61
  62 #define MONO_NEGATED_RELATION(r) ((~(r))&MONO_ANY_RELATION)
  63 #define MONO_SYMMETRIC_RELATION(r) (((r)&MONO_EQ_RELATION)|(((r)&MONO_LT_RELATION)<<1)|((r&MONO_GT_RELATION)>>1))
  64
  65
  66
  67 static void
  68 print_relation (int relation) {
  69         int print_or = 0;
  70         printf ("(");
  71         if (relation & MONO_LT_RELATION) {
  72                 printf ("LT");
  73                 print_or = 1;
  74         }
  75         if (relation & MONO_EQ_RELATION) {
  76                 if (print_or) {
  77                         printf ("|");
  78                 }
  79                 printf ("EQ");
  80                 print_or = 1;
  81         }
  82         if (relation & MONO_GT_RELATION) {
  83                 if (print_or) {
  84                         printf ("|");
  85                 }
  86                 printf ("GT");
  87                 print_or = 1;
  88         }
  89         printf (")");
  90 }
  91
  92 static void
  93 print_summarized_value (MonoSummarizedValue *value) {
  94         switch (value->type) {
  95         case MONO_ANY_SUMMARIZED_VALUE:
  96                 printf ("ANY");
  97                 break;
  98         case MONO_CONSTANT_SUMMARIZED_VALUE:
  99                 printf ("CONSTANT %d", value->value.constant.value);
 100                 break;
 101         case MONO_VARIABLE_SUMMARIZED_VALUE:
 102                 printf ("VARIABLE %d, delta %d", value->value.variable.variable, value->value.variable.delta);
 103                 break;
 104         case MONO_PHI_SUMMARIZED_VALUE: {
 105                 int phi;
 106                 printf ("PHI (");
 107                 for (phi = 0; phi < value->value.phi.number_of_alternatives; phi++) {
 108                         if (phi) printf (",");
 109                         printf ("%d", value->value.phi.phi_alternatives [phi]);
 110                 }
 111                 printf (")");
 112                 break;
 113         }
 114         default:
 115                 g_assert_not_reached ();
 116         }
 117 }
 118
 119 static void
 120 print_summarized_value_relation (MonoSummarizedValueRelation *relation) {
 121         printf ("Relation ");
 122         print_relation (relation->relation);
 123         printf (" with value ");
 124         print_summarized_value (&(relation->related_value));
 125 }
 126
 127 #if 0
 128 static void
 129 print_summarized_value_relation_chain (MonoSummarizedValueRelation *relation) {
 130         printf ("Relations:\n");
 131         while (relation) {
 132                 print_summarized_value_relation (relation);
 133                 printf ("\n");
 134                 relation = relation->next;
 135         }
 136 }
 137 #endif
 138
 139 static void
 140 print_evaluation_context_status (MonoRelationsEvaluationStatus status) {
 141         if (status == MONO_RELATIONS_EVALUATION_NOT_STARTED) {
 142                 printf ("EVALUATION_NOT_STARTED");
 143         } else {
 144                 gboolean print_or = FALSE;
 145
 146                 printf ("(");
 147                 if (status & MONO_RELATIONS_EVALUATION_IN_PROGRESS) {
 148                         if (print_or) printf ("|");
 149                         printf ("EVALUATION_IN_PROGRESS");
 150                         print_or = TRUE;
 151                 }
 152                 if (status & MONO_RELATIONS_EVALUATION_COMPLETED) {
 153                         if (print_or) printf ("|");
 154                         printf ("EVALUATION_COMPLETED");
 155                         print_or = TRUE;
 156                 }
 157                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
 158                         if (print_or) printf ("|");
 159                         printf ("RECURSIVELY_ASCENDING");
 160                         print_or = TRUE;
 161                 }
 162                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
 163                         if (print_or) printf ("|");
 164                         printf ("RECURSIVELY_DESCENDING");
 165                         print_or = TRUE;
 166                 }
 167                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
 168                         if (print_or) printf ("|");
 169                         printf ("RECURSIVELY_INDEFINITE");
 170                         print_or = TRUE;
 171                 }
 172                 printf (")");
 173         }
 174 }
 175
 176
 177 static void
 178 print_evaluation_context_ranges (MonoRelationsEvaluationRanges *ranges) {
 179         printf ("(ranges: zero [%d,%d], variable [%d,%d])", ranges->zero.lower, ranges->zero.upper, ranges->variable.lower, ranges->variable.upper);
 180 }
 181
 182 static void
 183 print_evaluation_context (MonoRelationsEvaluationContext *context) {
 184         printf ("Context status: ");
 185         print_evaluation_context_status (context->status);
 186         if (context->status & (MONO_RELATIONS_EVALUATION_IN_PROGRESS|MONO_RELATIONS_EVALUATION_COMPLETED)) {
 187                 print_evaluation_context_ranges (&(context->ranges));
 188         }
 189         printf ("\n");
 190 }
 191
 192 #if 0
 193 static void
 194 print_evaluation_area (MonoVariableRelationsEvaluationArea *area) {
 195         int i;
 196         printf ("Dump of evaluation area (%d variables):\n", area->cfg->num_varinfo);
 197         for (i = 0; i < area->cfg->num_varinfo; i++) {
 198                 printf ("Variable %d: ", i);
 199                 print_evaluation_context (&(area->contexts [i]));
 200                 print_summarized_value_relation_chain (&(area->relations [i]));
 201         }
 202 }
 203
 204 static void
 205 print_evaluation_area_contexts (MonoVariableRelationsEvaluationArea *area) {
 206         int i;
 207         printf ("Dump of evaluation area contexts (%d variables):\n", area->cfg->num_varinfo);
 208         for (i = 0; i < area->cfg->num_varinfo; i++) {
 209                 printf ("Variable %d: ", i);
 210                 print_evaluation_context (&(area->contexts [i]));
 211         }
 212 }
 213 #endif
 214
 215 /*
 216  * Given a MonoInst, if it is a store to a variable return the MonoInst that
 217  * represents the stored value.
 218  * If anything goes wrong, return NULL.
 219  * store: the MonoInst that should be a store
 220  * expected_variable_index: the variable where the value should be stored
 221  * return: either the stored value, or NULL
 222  */
 223 static MonoInst *
 224 get_variable_value_from_store_instruction (MonoInst *store, int expected_variable_index) {
 225         switch (store->opcode) {
 226         case CEE_STIND_REF:
 227         case CEE_STIND_I:
 228         case CEE_STIND_I4:
 229         case CEE_STIND_I1:
 230         case CEE_STIND_I2:
 231         case CEE_STIND_I8:
 232         case CEE_STIND_R4:
 233         case CEE_STIND_R8:
 234                 if (TRACE_ABC_REMOVAL) {
 235                         printf ("[store instruction found]");
 236                 }
 237                 if ((store->inst_left->opcode == OP_LOCAL) || (store->inst_left->opcode == OP_ARG)) {
 238                         int variable_index = store->inst_left->inst_c0;
 239                         if (TRACE_ABC_REMOVAL) {
 240                                 printf ("[value put in local %d (expected %d)]", variable_index, expected_variable_index);
 241                         }
 242                         if (variable_index == expected_variable_index) {
 243                                 return store->inst_right;
 244                         } else {
 245                                 return NULL;
 246                         }
 247                 }
 248                 else
 249                 {
 250                         return NULL;
 251                 }
 252                 break;
 253         default:
 254                 return NULL;
 255         }
 256 }
 257
 258 /*
 259  * Check if the delta of an integer variable value is safe with respect
 260  * to the variable size in bytes and its kind (signed or unsigned).
 261  * If the delta is not safe, make the value an "any".
 262  */
 263 static void
 264 check_delta_safety (MonoVariableRelationsEvaluationArea *area, MonoSummarizedValue *value) {
 265         if (value->type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 266                 int variable = value->value.variable.variable;
 267                 int delta = value->value.variable.delta;
 268                 if ((area->variable_value_kind [variable]) & MONO_UNSIGNED_VALUE_FLAG) {
 269                         if (delta < 0) {
 270                                 MAKE_VALUE_ANY (*value);
 271                         }
 272                 } else {
 273                         if (((area->variable_value_kind [variable]) & MONO_INTEGER_VALUE_SIZE_BITMASK) < 4) {
 274                                 MAKE_VALUE_ANY (*value);
 275                         } else if (delta > 16) {
 276                                 MAKE_VALUE_ANY (*value);
 277                         }
 278                 }
 279         }
 280 }
 281
 282 /* Prototype, definition comes later */
 283 static void
 284 summarize_array_value (MonoVariableRelationsEvaluationArea *area, MonoInst *value, MonoSummarizedValue *result, gboolean is_array_type);
 285
 286 /*
 287  * Given a MonoInst representing an integer value, store it in "summarized" form.
 288  * result_value_kind: the "expected" kind of result;
 289  * result: the "summarized" value
 290  * returns the "actual" kind of result, if guessable (otherwise MONO_UNKNOWN_INTEGER_VALUE)
 291  */
 292 static MonoIntegerValueKind
 293 summarize_integer_value (MonoVariableRelationsEvaluationArea *area, MonoInst *value, MonoSummarizedValue *result, MonoIntegerValueKind result_value_kind) {
 294         MonoIntegerValueKind value_kind;
 295
 296         if (value->type == STACK_I8) {
 297                 value_kind = MONO_INTEGER_VALUE_SIZE_8;
 298         } else if (value->type == STACK_I4) {
 299                 value_kind = MONO_INTEGER_VALUE_SIZE_4;
 300         } else {
 301                 value_kind = MONO_UNKNOWN_INTEGER_VALUE;
 302         }
 303
 304         switch (value->opcode) {
 305         case OP_ICONST:
 306                 result->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 307                 result->value.constant.value = value->inst_c0;
 308                 break;
 309         case OP_LOCAL:
 310         case OP_ARG:
 311                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 312                 result->value.variable.variable = value->inst_c0;
 313                 result->value.variable.delta = 0;
 314                 value_kind = area->variable_value_kind [value->inst_c0];
 315                 break;
 316         case CEE_LDIND_I1:
 317                 value_kind = MONO_INTEGER_VALUE_SIZE_1;
 318                 goto handle_load;
 319         case CEE_LDIND_U1:
 320                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
 321                 goto handle_load;
 322         case CEE_LDIND_I2:
 323                 value_kind = MONO_INTEGER_VALUE_SIZE_2;
 324                 goto handle_load;
 325         case CEE_LDIND_U2:
 326                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
 327                 goto handle_load;
 328         case CEE_LDIND_I4:
 329                 value_kind = MONO_INTEGER_VALUE_SIZE_4;
 330                 goto handle_load;
 331         case CEE_LDIND_U4:
 332                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
 333                 goto handle_load;
 334         case CEE_LDIND_I8:
 335                 value_kind = MONO_INTEGER_VALUE_SIZE_8;
 336                 goto handle_load;
 337         case CEE_LDIND_I:
 338                 value_kind = SIZEOF_VOID_P;
 339 handle_load:
 340                 if ((value->inst_left->opcode == OP_LOCAL) || (value->inst_left->opcode == OP_ARG)) {
 341                         value_kind = summarize_integer_value (area, value->inst_left, result, result_value_kind);
 342                 } else {
 343                         MAKE_VALUE_ANY (*result);
 344                 }
 345                 break;
 346         case CEE_ADD: {
 347                 MonoSummarizedValue left_value;
 348                 MonoSummarizedValue right_value;
 349                 summarize_integer_value (area, value->inst_left, &left_value, result_value_kind);
 350                 summarize_integer_value (area, value->inst_right, &right_value, result_value_kind);
 351
 352                 if (left_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 353                         if (right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 354                                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 355                                 result->value.variable.variable = left_value.value.variable.variable;
 356                                 result->value.variable.delta = left_value.value.variable.delta + right_value.value.constant.value;
 357                         } else {
 358                                 MAKE_VALUE_ANY (*result);
 359                         }
 360                 } else if (right_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 361                         if (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 362                                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 363                                 result->value.variable.variable = right_value.value.variable.variable;
 364                                 result->value.variable.delta = left_value.value.constant.value + right_value.value.variable.delta;
 365                         } else {
 366                                 MAKE_VALUE_ANY (*result);
 367                         }
 368                 } else if ((right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) && (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE)) {
 369                         /* This should not happen if constant folding has been done */
 370                         result->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 371                         result->value.constant.value = left_value.value.constant.value + right_value.value.constant.value;
 372                 } else {
 373                         MAKE_VALUE_ANY (*result);
 374                 }
 375                 if (result->type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 376                         check_delta_safety (area, result);
 377                 }
 378                 break;
 379         }
 380         case CEE_SUB: {
 381                 MonoSummarizedValue left_value;
 382                 MonoSummarizedValue right_value;
 383                 summarize_integer_value (area, value->inst_left, &left_value, result_value_kind);
 384                 summarize_integer_value (area, value->inst_right, &right_value, result_value_kind);
 385
 386                 if (left_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 387                         if (right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 388                                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 389                                 result->value.variable.variable = left_value.value.variable.variable;
 390                                 result->value.variable.delta = left_value.value.variable.delta - right_value.value.constant.value;
 391                         } else {
 392                                 MAKE_VALUE_ANY (*result);
 393                         }
 394                 } else if ((right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) && (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE)) {
 395                         /* This should not happen if constant folding has been done */
 396                         result->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 397                         result->value.constant.value = left_value.value.constant.value - right_value.value.constant.value;
 398                 } else {
 399                         MAKE_VALUE_ANY (*result);
 400                 }
 401                 if (result->type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 402                         check_delta_safety (area, result);
 403                 }
 404                 break;
 405         }
 406         case CEE_AND: {
 407                 MonoSummarizedValue left_value;
 408                 MonoSummarizedValue right_value;
 409                 int constant_operand_value;
 410
 411                 summarize_integer_value (area, value->inst_left, &left_value, result_value_kind);
 412                 summarize_integer_value (area, value->inst_right, &right_value, result_value_kind);
 413
 414                 if (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 415                         constant_operand_value = left_value.value.constant.value;
 416                 } else if (right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 417                         constant_operand_value = right_value.value.constant.value;
 418                 } else {
 419                         constant_operand_value = 0;
 420                 }
 421
 422                 if (constant_operand_value > 0) {
 423                         if (constant_operand_value <= 0xff) {
 424                                 if ((result_value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) > 1) {
 425                                         value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
 426                                 }
 427                         } else if (constant_operand_value <= 0xffff) {
 428                                 if ((result_value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) > 2) {
 429                                         value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
 430                                 }
 431                         }
 432                 }
 433
 434                 MAKE_VALUE_ANY (*result);
 435                 break;
 436         }
 437         case CEE_CONV_I1:
 438         case CEE_CONV_OVF_I1:
 439         case CEE_CONV_OVF_I1_UN:
 440                 value_kind = MONO_INTEGER_VALUE_SIZE_1;
 441                 MAKE_VALUE_ANY (*result);
 442                 break;
 443         case CEE_CONV_U1:
 444         case CEE_CONV_OVF_U1:
 445                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
 446                 MAKE_VALUE_ANY (*result);
 447                 break;
 448         case CEE_CONV_I2:
 449         case CEE_CONV_OVF_I2:
 450         case CEE_CONV_OVF_I2_UN:
 451                 value_kind = MONO_INTEGER_VALUE_SIZE_2;
 452                 MAKE_VALUE_ANY (*result);
 453                 break;
 454         case CEE_CONV_U2:
 455         case CEE_CONV_OVF_U2:
 456                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
 457                 MAKE_VALUE_ANY (*result);
 458                 break;
 459         case CEE_LDLEN:
 460                 summarize_array_value (area, value->inst_left, result, TRUE);
 461                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
 462                 break;
 463         case OP_PHI:
 464                 result->type = MONO_PHI_SUMMARIZED_VALUE;
 465                 result->value.phi.number_of_alternatives = *(value->inst_phi_args);
 466                 result->value.phi.phi_alternatives = value->inst_phi_args + 1;
 467                 break;
 468         default:
 469                 MAKE_VALUE_ANY (*result);
 470         }
 471         return value_kind;
 472 }
 473
 474 /*
 475  * Given a MonoInst representing an array value, store it in "summarized" form.
 476  * result: the "summarized" value
 477  * is_array_type: TRUE of we are *sure* that an eventual OP_PCONST will point
 478  * to a MonoArray (this can happen for already initialized readonly static fields,
 479  * in which case we will get the array length directly from the MonoArray)
 480  */
 481 static void
 482 summarize_array_value (MonoVariableRelationsEvaluationArea *area, MonoInst *value, MonoSummarizedValue *result, gboolean is_array_type) {
 483         switch (value->opcode) {
 484         case OP_LOCAL:
 485         case OP_ARG:
 486                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 487                 result->value.variable.variable = value->inst_c0;
 488                 result->value.variable.delta = 0;
 489                 break;
 490         case CEE_LDIND_REF:
 491                 summarize_array_value (area, value->inst_left, result, FALSE);
 492                 break;
 493         case CEE_NEWARR:
 494                 summarize_integer_value (area, value->inst_newa_len, result, MONO_UNKNOWN_INTEGER_VALUE);
 495                 break;
 496         case OP_PCONST:
 497                 if ((is_array_type) && (value->inst_p0 != NULL)) {
 498                         MonoArray *array = (MonoArray *) (value->inst_p0);
 499                         result->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 500                         result->value.constant.value = array->max_length;
 501                 } else {
 502                         MAKE_VALUE_ANY (*result);
 503                 }
 504                 break;
 505         case OP_PHI:
 506                 result->type = MONO_PHI_SUMMARIZED_VALUE;
 507                 result->value.phi.number_of_alternatives = *(value->inst_phi_args);
 508                 result->value.phi.phi_alternatives = value->inst_phi_args + 1;
 509                 break;
 510         default:
 511                 MAKE_VALUE_ANY (*result);
 512         }
 513 }
 514
 515 static MonoValueRelation
 516 get_relation_from_branch_instruction (int opcode) {
 517         switch (opcode) {
 518         case CEE_BEQ:
 519                 return MONO_EQ_RELATION;
 520         case CEE_BLT:
 521         case CEE_BLT_UN:
 522                 return MONO_LT_RELATION;
 523         case CEE_BLE:
 524         case CEE_BLE_UN:
 525                 return MONO_LE_RELATION;
 526         case CEE_BGT:
 527         case CEE_BGT_UN:
 528                 return MONO_GT_RELATION;
 529         case CEE_BGE:
 530         case CEE_BGE_UN:
 531                 return MONO_GE_RELATION;
 532         case CEE_BNE_UN:
 533                 return MONO_NE_RELATION;
 534         default:
 535                 return MONO_ANY_RELATION;
 536         }
 537 }
 538
 539 /*
 540  * Given a BB, find its entry condition and put its relations in a
 541  * "MonoAdditionalVariableRelationsForBB" structure.
 542  * bb: the BB
 543  * relations: the resulting relations (entry condition of the given BB)
 544  */
 545 static void
 546 get_relations_from_previous_bb (MonoVariableRelationsEvaluationArea *area, MonoBasicBlock *bb, MonoAdditionalVariableRelationsForBB *relations) {
 547         MonoBasicBlock *in_bb;
 548         MonoInst *branch;
 549         MonoValueRelation branch_relation;
 550         MonoValueRelation symmetric_relation;
 551
 552         INITIALIZE_VALUE_RELATION (&(relations->relation1.relation));
 553         relations->relation1.relation.relation_is_static_definition = FALSE;
 554         relations->relation1.insertion_point = NULL;
 555         relations->relation1.variable = -1;
 556         INITIALIZE_VALUE_RELATION (&(relations->relation2.relation));
 557         relations->relation2.relation.relation_is_static_definition = FALSE;
 558         relations->relation2.insertion_point = NULL;
 559         relations->relation2.variable = -1;
 560
 561
 562         if (bb->in_count == 1) { /* Should write the code to "sum" conditions... */
 563                 in_bb = bb->in_bb [0];
 564                 branch = in_bb->last_ins;
 565                 if (branch == NULL) return;
 566                 branch_relation = get_relation_from_branch_instruction (branch->opcode);
 567                 if ((branch_relation != MONO_ANY_RELATION) && (branch->inst_left->opcode == OP_COMPARE)) {
 568                         MonoSummarizedValue left_value;
 569                         MonoSummarizedValue right_value;
 570                         gboolean code_path;
 571
 572                         if (branch->inst_true_bb == bb) {
 573                                 code_path = TRUE;
 574                         } else if (branch->inst_false_bb == bb) {
 575                                 code_path = FALSE;
 576                         } else {
 577                                 code_path = TRUE;
 578                                 g_assert_not_reached ();
 579                         }
 580
 581                         if (!code_path) {
 582                                 branch_relation = MONO_NEGATED_RELATION (branch_relation);
 583                         }
 584                         symmetric_relation = MONO_SYMMETRIC_RELATION (branch_relation);
 585
 586                         summarize_integer_value (area, branch->inst_left->inst_left, &left_value, MONO_UNKNOWN_INTEGER_VALUE);
 587                         summarize_integer_value (area, branch->inst_left->inst_right, &right_value, MONO_UNKNOWN_INTEGER_VALUE);
 588
 589                         if ((left_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) && ((right_value.type == MONO_VARIABLE_SUMMARIZED_VALUE)||(right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE))) {
 590                                 relations->relation1.variable = left_value.value.variable.variable;
 591                                 relations->relation1.relation.relation = branch_relation;
 592                                 relations->relation1.relation.related_value = right_value;
 593                                 if (right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 594                                         relations->relation1.relation.related_value.value.constant.value -= left_value.value.variable.delta;
 595                                 } else {
 596                                         relations->relation1.relation.related_value.value.variable.delta -= left_value.value.variable.delta;
 597                                 }
 598                         }
 599                         if ((right_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) && ((left_value.type == MONO_VARIABLE_SUMMARIZED_VALUE)||(left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE))) {
 600                                 relations->relation2.variable = right_value.value.variable.variable;
 601                                 relations->relation2.relation.relation = symmetric_relation;
 602                                 relations->relation2.relation.related_value = left_value;
 603                                 if (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 604                                         relations->relation2.relation.related_value.value.constant.value -= right_value.value.variable.delta;
 605                                 } else {
 606                                         relations->relation2.relation.related_value.value.variable.delta -= right_value.value.variable.delta;
 607                                 }
 608                         }
 609                 }
 610         }
 611 }
 612
 613
 614 /*
 615  * Add the given relations to the evaluation area.
 616  * area: the evaluation area
 617  * change: the relations that must be added
 618  */
 619 static void
 620 apply_change_to_evaluation_area (MonoVariableRelationsEvaluationArea *area, MonoAdditionalVariableRelation *change) {
 621         MonoSummarizedValueRelation *base_relation;
 622
 623         if (change->relation.relation != MONO_ANY_RELATION) {
 624                 base_relation = &(area->relations [change->variable]);
 625                 while ((base_relation->next != NULL) && (base_relation->next->relation_is_static_definition)) {
 626                         base_relation = base_relation->next;
 627                 }
 628                 change->insertion_point = base_relation;
 629                 change->relation.next = base_relation->next;
 630                 base_relation->next = &(change->relation);
 631         }
 632 }
 633
 634 /*
 635  * Remove the given relation from the evaluation area.
 636  * change: the relation that must be removed
 637  */
 638 static void
 639 remove_change_from_evaluation_area (MonoAdditionalVariableRelation *change) {
 640         if (change->insertion_point != NULL) {
 641                 change->insertion_point->next = change->relation.next;
 642                 change->relation.next = NULL;
 643         }
 644 }
 645
 646
 647 static void
 648 clean_contexts (MonoRelationsEvaluationContext *contexts, int number) {
 649         int i;
 650         for (i = 0; i < number; i++) {
 651                 contexts [i].status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
 652         }
 653 }
 654
 655
 656 /*
 657  * Perform the intersection of a range and a constant value (taking into
 658  * account the relation that the value has with the range).
 659  * range: the range that will be intersected with the value
 660  * value: the value that will be intersected with the range
 661  * relation: the relation between the range and the value
 662  */
 663 static void
 664 intersect_value( MonoRelationsEvaluationRange *range, int value, MonoValueRelation relation ) {
 665         switch (relation) {
 666         case MONO_NO_RELATION:
 667                 MONO_MAKE_RELATIONS_EVALUATION_RANGE_IMPOSSIBLE (*range);
 668                 break;
 669         case MONO_ANY_RELATION:
 670                 break;
 671         case MONO_EQ_RELATION:
 672                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
 673                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
 674                 break;
 675         case MONO_NE_RELATION: {
 676                 /* IMPROVEMENT Figure this out! (ignoring it is safe anyway) */
 677                 break;
 678         }
 679         case MONO_LT_RELATION:
 680                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (value));
 681                 break;
 682         case MONO_LE_RELATION:
 683                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
 684                 break;
 685         case MONO_GT_RELATION:
 686                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (value));
 687                 break;
 688         case MONO_GE_RELATION:
 689                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
 690                 break;
 691         default:
 692                 g_assert_not_reached();
 693         }
 694 }
 695
 696
 697 /*
 698  * Perform the intersection of two pairs of ranges (taking into account the
 699  * relation between the ranges and a given delta).
 700  * ranges: the ranges that will be intersected
 701  * other_ranges the other ranges that will be intersected
 702  * delta: the delta between the pairs of ranges
 703  * relation: the relation between the pairs of ranges
 704  */
 705 static void
 706 intersect_ranges( MonoRelationsEvaluationRanges *ranges, MonoRelationsEvaluationRanges *other_ranges, int delta, MonoValueRelation relation ) {
 707         if (delta == 0) {
 708                 switch (relation) {
 709                 case MONO_NO_RELATION:
 710                         MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (*ranges);
 711                         break;
 712                 case MONO_ANY_RELATION:
 713                         break;
 714                 case MONO_EQ_RELATION:
 715                         MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (*ranges, *other_ranges);
 716                         break;
 717                 case MONO_NE_RELATION: {
 718                         /* FIXME Figure this out! (ignoring it is safe anyway) */
 719                         break;
 720                 }
 721                 case MONO_LT_RELATION:
 722                         MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->zero.upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->zero.upper));
 723                         MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->variable.upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->variable.upper));
 724                         break;
 725                 case MONO_LE_RELATION:
 726                         MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->zero.upper, other_ranges->zero.upper);
 727                         MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->variable.upper, other_ranges->variable.upper);
 728                         break;
 729                 case MONO_GT_RELATION:
 730                         MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->zero.lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->zero.lower));
 731                         MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->variable.lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->variable.lower));
 732                         break;
 733                 case MONO_GE_RELATION:
 734                         MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->zero.lower, other_ranges->zero.lower);
 735                         MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->variable.lower, other_ranges->variable.lower);
 736                         break;
 737                 default:
 738                         g_assert_not_reached();
 739                 }
 740         } else {
 741                 MonoRelationsEvaluationRanges translated_ranges = *other_ranges;
 742                 MONO_ADD_DELTA_SAFELY_TO_RANGES (translated_ranges, delta);
 743                 intersect_ranges( ranges, &translated_ranges, FALSE, relation );
 744         }
 745 }
 746
 747 /*
 748  * Recursive method that traverses the relation graph to evaluate the
 749  * relation between two variables.
 750  * At the end of the execution, the resulting ranges are in the context of
 751  * the "starting" variable.
 752  * area: the current evaluation area (it contains the relation graph and
 753  *       memory for all the evaluation contexts is already allocated)
 754  * variable: starting variable (the value ranges in its context are the result
 755  *           of the execution of this procedure)
 756  * target_variable: the variable with respect to which the starting variable
 757  *                  is evaluated (tipically the starting variable is the index
 758  *                  and the target one is the array (which means its length))
 759  * father_context: the previous evaluation context in recursive invocations
 760  *                 (or NULL for the first invocation)
 761  */
 762 static void
 763 evaluate_relation_with_target_variable (MonoVariableRelationsEvaluationArea *area, int variable, int target_variable, MonoRelationsEvaluationContext *father_context) {
 764         MonoRelationsEvaluationContext *context = &(area->contexts [variable]);
 765
 766         // First of all, we check the evaluation status
 767         // (what must be done is *very* different in each case)
 768         switch (context->status) {
 769         case MONO_RELATIONS_EVALUATION_NOT_STARTED: {
 770                 MonoSummarizedValueRelation *relation = &(area->relations [variable]);
 771
 772                 if (TRACE_ABC_REMOVAL) {
 773                         printf ("Evaluating varible %d (target variable %d)\n", variable, target_variable);
 774                         print_summarized_value_relation (relation);
 775                         printf ("\n");
 776                 }
 777
 778                 // We properly inizialize the context
 779                 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
 780                 context->father = father_context;
 781                 MONO_MAKE_RELATIONS_EVALUATION_RANGES_WEAK (context->ranges);
 782
 783                 // If we have found the target variable, we can set the range
 784                 // related to it in the context to "equal" (which is [0,0])
 785                 if (variable == target_variable) {
 786                         if (TRACE_ABC_REMOVAL) {
 787                                 printf ("Target variable reached (%d), continuing to evaluate relations with constants\n", variable);
 788                         }
 789                         context->ranges.variable.lower = 0;
 790                         context->ranges.variable.upper = 0;
 791                 }
 792
 793                 // Examine all relations for this variable (scan the list)
 794                 // The contribute of each relation will be intersected (logical and)
 795                 while (relation != NULL) {
 796                         context->current_relation = relation;
 797
 798                         if (TRACE_ABC_REMOVAL) {
 799                                 printf ("Processing (%d): ", variable);
 800                                 print_summarized_value_relation (relation);
 801                                 printf ("\n");
 802                         }
 803
 804                         // We decie what to do according the the type of the related value
 805                         switch (relation->related_value.type) {
 806                         case MONO_ANY_SUMMARIZED_VALUE:
 807                                 // No added information, skip it
 808                                 break;
 809                         case MONO_CONSTANT_SUMMARIZED_VALUE:
 810                                 // Intersect range with constant (taking into account the relation)
 811                                 intersect_value (&(context->ranges.zero), relation->related_value.value.constant.value, relation->relation);
 812                                 break;
 813                         case MONO_VARIABLE_SUMMARIZED_VALUE:
 814                                 // Generally, evaluate related variable and intersect ranges.
 815                                 // However, some check is necessary...
 816
 817                                 // If the relation is "ANY", nothing to do (no added information)
 818                                 if (relation->relation != MONO_ANY_RELATION) {
 819                                         int related_variable = relation->related_value.value.variable.variable;
 820                                         MonoRelationsEvaluationContext *related_context = &(area->contexts [related_variable]);
 821
 822                                         // The second condition in the "or" avoids messing with "back edges" in the graph traversal
 823                                         // (they are simply ignored instead of triggering the handling of recursion)
 824                                         if ( (related_context->status == MONO_RELATIONS_EVALUATION_NOT_STARTED) || !
 825                                                         ((related_context->current_relation->related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) &&
 826                                                         (related_context->current_relation->related_value.value.variable.variable == variable))) {
 827                                                 // Evaluate the related variable
 828                                                 evaluate_relation_with_target_variable (area, related_variable, target_variable, context);
 829
 830                                                 // Check if we are part of a recursive loop
 831                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
 832                                                         if (TRACE_ABC_REMOVAL) {
 833                                                                 printf ("Recursivity detected for varible %d (target variable %d), status ", variable, target_variable);
 834                                                                 print_evaluation_context_status (context->status);
 835                                                         }
 836
 837                                                         // If we are, check if the evaluation of the related variable is complete
 838                                                         if (related_context->status == MONO_RELATIONS_EVALUATION_COMPLETED) {
 839                                                                 // If it is complete, we are part of a recursive definition.
 840                                                                 // Since it is a *definition* (and definitions are evaluated *before*
 841                                                                 // conditions because they are first in the list), intersection is not
 842                                                                 // strictly necessary, we simply copy the ranges and apply the delta
 843                                                                 context->ranges = related_context->ranges;
 844                                                                 /* Delta has already been checked for over/under-flow when evaluating values */
 845                                                                 MONO_ADD_DELTA_SAFELY_TO_RANGES (context->ranges, relation->related_value.value.variable.delta);
 846                                                                 context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
 847                                                                 if (TRACE_ABC_REMOVAL) {
 848                                                                         printf (", ranges already computed, result: \n");
 849                                                                         print_evaluation_context_ranges (&(context->ranges));
 850                                                                         printf (" (delta is %d)\n", relation->related_value.value.variable.delta);
 851                                                                 }
 852                                                         } else {
 853                                                                 // If it is not complete, do nothing (we do not have enough information)
 854                                                                 if (TRACE_ABC_REMOVAL) {
 855                                                                         printf (", ranges not computed\n");
 856                                                                 }
 857                                                         }
 858                                                 } else {
 859                                                         // If we are not (the common case) intersect the result
 860                                                         intersect_ranges( &(context->ranges), &(related_context->ranges), relation->related_value.value.variable.delta, relation->relation );
 861                                                 }
 862                                         } else {
 863                                                 if (TRACE_ABC_REMOVAL) {
 864                                                         printf ("Relation is a back-edge in this traversal, skipping\n");
 865                                                 }
 866                                         }
 867                                 }
 868                                 break;
 869                         case MONO_PHI_SUMMARIZED_VALUE: {
 870                                 // We must compute all PHI alternatives, combining the results (with a union, which is a logical "or"),
 871                                 // and intersect this result with the ranges in the context; we must also take into account recursions
 872                                 // (with loops that can be ascending, descending, or indefinite)
 873                                 MonoRelationsEvaluationRanges phi_ranges;
 874                                 int phi;
 875                                 gboolean is_ascending = FALSE;
 876                                 gboolean is_descending = FALSE;
 877
 878                                 MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (phi_ranges);
 879                                 for (phi = 0; phi < relation->related_value.value.phi.number_of_alternatives; phi++) {
 880                                         int phi_alternative = relation->related_value.value.phi.phi_alternatives [phi];
 881                                         evaluate_relation_with_target_variable (area, phi_alternative, target_variable, context);
 882
 883                                         // This means we are part of a recursive loop
 884                                         if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
 885                                                 if (TRACE_ABC_REMOVAL) {
 886                                                         printf ("Recursivity detected for varible %d (target variable %d), status ", variable, target_variable);
 887                                                         print_evaluation_context_status (context->status);
 888                                                         printf ("\n");
 889                                                 }
 890                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
 891                                                         is_ascending = TRUE;
 892                                                 }
 893                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
 894                                                         is_descending = TRUE;
 895                                                 }
 896                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
 897                                                         is_ascending = TRUE;
 898                                                         is_descending = TRUE;
 899                                                 }
 900
 901                                                 // Clear "recursivity" bits in the status (recursion has been handled)
 902                                                 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
 903                                         } else {
 904                                                 MONO_RELATIONS_EVALUATION_RANGES_UNION (phi_ranges, area->contexts [phi_alternative].ranges);
 905                                         }
 906                                 }
 907
 908                                 // Apply the effects of all recursive loops
 909                                 if (is_ascending) {
 910                                         phi_ranges.zero.upper = INT_MAX;
 911                                         phi_ranges.variable.upper = INT_MAX;
 912                                 }
 913                                 if (is_descending) {
 914                                         phi_ranges.zero.lower = INT_MIN;
 915                                         phi_ranges.variable.lower = INT_MIN;
 916                                 }
 917
 918                                 // Intersect final result
 919                                 MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (context->ranges, phi_ranges);
 920                                 break;
 921                         }
 922                         default:
 923                                 g_assert_not_reached();
 924                         }
 925
 926                         // Pass to next relation
 927                         relation = relation->next;
 928                 }
 929
 930                 // Check if any recursivity bits are still in the status, and in any case clear them
 931                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
 932                         if (TRACE_ABC_REMOVAL) {
 933                                 printf ("Recursivity for varible %d (target variable %d) discards computation, status ", variable, target_variable);
 934                                 print_evaluation_context_status (context->status);
 935                                 printf ("\n");
 936                         }
 937                         // If yes, we did not have enough information (most likely we were evaluated inside a PHI, but we also
 938                         // depended on the same PHI, which was still in evaluation...), so clear the status to "NOT_STARTED"
 939                         // (if we will be evaluated again, the PHI will be already done, so our evaluation will succeed)
 940                         context->status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
 941                 } else {
 942                         if (TRACE_ABC_REMOVAL) {
 943                                 printf ("Ranges for varible %d (target variable %d) computed: ", variable, target_variable);
 944                                 print_evaluation_context_ranges (&(context->ranges));
 945                                 printf ("\n");
 946                         }
 947                         // If not (the common case) the evaluation is complete, and the result is in the context
 948                         context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
 949                 }
 950                 break;
 951         }
 952         case MONO_RELATIONS_EVALUATION_IN_PROGRESS: {
 953                 // This means we are in a recursive loop
 954                 MonoRelationsEvaluationContext *current_context = father_context;
 955                 MonoRelationsEvaluationContext *last_context = context->father;
 956                 gboolean evaluation_can_be_recursive = TRUE;
 957                 gboolean evaluation_is_definition = TRUE;
 958                 int path_value = 0;
 959
 960                 if (TRACE_ABC_REMOVAL) {
 961                         printf ("Evaluation of varible %d (target variable %d) already in progress\n", variable, target_variable);
 962                         print_evaluation_context (context);
 963                         print_summarized_value_relation (context->current_relation);
 964                         printf ("\n");
 965                 }
 966
 967                 // We must check if the loop can be a recursive definition (we scan the whole loop)
 968                 while (current_context != last_context) {
 969                         if (current_context == NULL) {
 970                                 printf ("Broken recursive ring in ABC removal\n");
 971                                 g_assert_not_reached ();
 972                         }
 973
 974                         if (current_context->current_relation->relation_is_static_definition) {
 975                                 if (current_context->current_relation->related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 976                                         /* No need to check path_value for over/under-flow, since delta should be safe */
 977                                         path_value += current_context->current_relation->related_value.value.variable.delta;
 978                                 } else if (current_context->current_relation->related_value.type != MONO_PHI_SUMMARIZED_VALUE) {
 979                                         evaluation_can_be_recursive = FALSE;
 980                                 }
 981                         } else {
 982                                 evaluation_is_definition = FALSE;
 983                                 evaluation_can_be_recursive = FALSE;
 984                         }
 985
 986                         current_context = current_context->father;
 987                 }
 988
 989                 // If this is a recursive definition, we properly flag the status in all the involved contexts
 990                 if (evaluation_is_definition) {
 991                         MonoRelationsEvaluationStatus recursive_status;
 992                         if (evaluation_can_be_recursive) {
 993                                 if (path_value > 0) {
 994                                         recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING;
 995                                 } else if (path_value < 0) {
 996                                         recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING;
 997                                 } else {
 998                                         recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
 999                                 }
1000                         } else {
1001                                 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
1002                         }
1003
1004                         if (TRACE_ABC_REMOVAL) {
1005                                 printf ("Recursivity accepted (");
1006                                 print_evaluation_context_status (recursive_status);
1007                                 printf (")\n");
1008                         }
1009
1010                         current_context = father_context;
1011                         while (current_context != last_context) {
1012                                 current_context->status |= recursive_status;
1013                                 current_context = current_context->father;
1014                         }
1015                 } else {
1016                         if (TRACE_ABC_REMOVAL) {
1017                                 printf ("Recursivity rejected (some relation in the cycle is not a defintion)\n");
1018                         }
1019                 }
1020                 break;
1021         }
1022         case MONO_RELATIONS_EVALUATION_COMPLETED: {
1023                 return;
1024         }
1025         default:
1026                 if (TRACE_ABC_REMOVAL) {
1027                         printf ("Varible %d (target variable %d) already in a recursive ring, skipping\n", variable, target_variable);
1028                         print_evaluation_context (context);
1029                         print_summarized_value_relation (context->current_relation);
1030                         printf ("\n");
1031                 }
1032                 break;
1033         }
1034
1035 }
1036
1037 /*
1038  * Apply the given value kind to the given range
1039  */
1040 static void apply_value_kind_to_range (MonoRelationsEvaluationRange *range, MonoIntegerValueKind value_kind) {
1041         if (value_kind != MONO_UNKNOWN_INTEGER_VALUE) {
1042                 if (value_kind & MONO_UNSIGNED_VALUE_FLAG) {
1043                         if (range->lower < 0) {
1044                                 range->lower = 0;
1045                         }
1046                         if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
1047                                 if (range->upper > 0xff) {
1048                                         range->upper = 0xff;
1049                                 }
1050                         } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
1051                                 if (range->upper > 0xffff) {
1052                                         range->upper = 0xffff;
1053                                 }
1054                         }
1055                 } else {
1056                         if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
1057                                 if (range->lower < -0x80) {
1058                                         range->lower = -0x80;
1059                                 }
1060                                 if (range->upper > 0x7f) {
1061                                         range->upper = 0x7f;
1062                                 }
1063                         } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
1064                                 if (range->lower < -0x8000) {
1065                                         range->lower = -0x8000;
1066                                 }
1067                                 if (range->upper > 0x7fff) {
1068                                         range->upper = 0x7fff;
1069                                 }
1070                         }
1071                 }
1072         }
1073 }
1074
1075 /*
1076  * Attempt the removal of bounds checks from a MonoInst.
1077  * inst: the MonoInst
1078  * area: the current evaluation area (it contains the relation graph and
1079  *       memory for all the evaluation contexts is already allocated)
1080  */
1081 static void
1082 remove_abc_from_inst (MonoInst *inst, MonoVariableRelationsEvaluationArea *area) {
1083         if (inst->opcode == CEE_LDELEMA) {
1084                 MonoInst *array_inst = inst->inst_left;
1085                 MonoInst *index_inst = inst->inst_right;
1086                 MonoSummarizedValue array_value;
1087                 MonoSummarizedValue index_value;
1088                 MonoIntegerValueKind index_value_kind;
1089
1090                 /* First of all, examine the CEE_LDELEMA operands */
1091                 summarize_array_value (area, array_inst, &array_value, TRUE);
1092                 index_value_kind = summarize_integer_value (area, index_inst, &index_value, MONO_UNKNOWN_INTEGER_VALUE);
1093
1094                 /* If the array is a local variable... */
1095                 if (array_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1096                         int array_variable = array_value.value.variable.variable;
1097                         MonoRelationsEvaluationContext *array_context = &(area->contexts [array_variable]);
1098
1099                         if (index_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
1100                                 // The easiest case: we just evaluate the array length, to see if it has some relation
1101                                 // with the index constant, and act accordingly
1102
1103                                 clean_contexts (area->contexts, area->cfg->num_varinfo);
1104                                 evaluate_relation_with_target_variable (area, array_variable, array_variable, NULL);
1105
1106                                 if ((index_value.value.constant.value >= 0) && (index_value.value.constant.value < array_context->ranges.zero.lower)) {
1107                                         if (REPORT_ABC_REMOVAL) {
1108                                                 printf ("ARRAY-ACCESS: removed bounds check on array %d with constant index %d in method %s\n",
1109                                                                 array_variable, index_value.value.constant.value, mono_method_full_name (area->cfg->method, TRUE));
1110                                         }
1111                                         inst->flags |= (MONO_INST_NORANGECHECK);
1112                                 }
1113                         } else if (index_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1114                                 // The common case: we must evaluate both the index and the array length, and check for relevant
1115                                 // relations both through variable definitions and as constant definitions
1116
1117                                 int index_variable = index_value.value.variable.variable;
1118                                 MonoRelationsEvaluationContext *index_context = &(area->contexts [index_variable]);
1119
1120                                 clean_contexts (area->contexts, area->cfg->num_varinfo);
1121
1122                                 evaluate_relation_with_target_variable (area, index_variable, array_variable, NULL);
1123                                 evaluate_relation_with_target_variable (area, array_variable, array_variable, NULL);
1124
1125                                 MONO_SUB_DELTA_SAFELY_FROM_RANGES (index_context->ranges, index_value.value.variable.delta);
1126                                 /* Apply index value kind */
1127                                 apply_value_kind_to_range (&(index_context->ranges.zero), index_value_kind);
1128
1129                                 if (index_context->ranges.zero.lower >= 0) {
1130                                         if (TRACE_ABC_REMOVAL) {
1131                                                 printf ("ARRAY-ACCESS: Removed lower bound check on array %d with index %d\n", array_variable, index_variable);
1132                                         }
1133                                         if ((index_context->ranges.variable.upper < 0)||(index_context->ranges.zero.upper < array_context->ranges.zero.lower)) {
1134                                                 if (REPORT_ABC_REMOVAL) {
1135                                                         printf ("ARRAY-ACCESS: removed bounds check on array %d with index %d in method %s\n",
1136                                                                         array_variable, index_variable, mono_method_full_name (area->cfg->method, TRUE));
1137                                                 }
1138                                                 inst->flags |= (MONO_INST_NORANGECHECK);
1139                                         }
1140                                 }
1141                                 if (TRACE_ABC_REMOVAL) {
1142                                         if (index_context->ranges.variable.upper < 0) {
1143                                                 printf ("ARRAY-ACCESS: Removed upper bound check (through variable) on array %d with index %d\n", array_variable, index_variable);
1144                                         }
1145                                         if (index_context->ranges.zero.upper < array_context->ranges.zero.lower) {
1146                                                 printf ("ARRAY-ACCESS: Removed upper bound check (through constant) on array %d with index %d\n", array_variable, index_variable);
1147                                         }
1148                                 }
1149                         }
1150                 } else if (array_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
1151                         if (index_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
1152                                 /* The easiest possible case: constant with constant */
1153                                 if ((index_value.value.constant.value >= 0) && (index_value.value.constant.value < array_value.value.constant.value)) {
1154                                         if (REPORT_ABC_REMOVAL) {
1155                                                 printf ("ARRAY-ACCESS: removed bounds check on array of constant length %d with constant index %d in method %s\n",
1156                                                                 array_value.value.constant.value, index_value.value.constant.value, mono_method_full_name (area->cfg->method, TRUE));
1157                                         }
1158                                         inst->flags |= (MONO_INST_NORANGECHECK);
1159                                 }
1160                         } else if (index_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1161                                 /* The index has a variable related value, which must be evaluated */
1162                                 int index_variable = index_value.value.variable.variable;
1163                                 MonoRelationsEvaluationContext *index_context = &(area->contexts [index_variable]);
1164
1165                                 clean_contexts (area->contexts, area->cfg->num_varinfo);
1166                                 evaluate_relation_with_target_variable (area, index_variable, index_variable, NULL);
1167                                 /* Apply index value kind */
1168                                 apply_value_kind_to_range (&(index_context->ranges.zero), index_value_kind);
1169
1170                                 if ((index_context->ranges.zero.lower >= 0) && (index_context->ranges.zero.upper < array_value.value.constant.value)) {
1171                                         if (REPORT_ABC_REMOVAL) {
1172                                                 printf ("ARRAY-ACCESS: removed bounds check on array of constant length %d with index %d ranging from %d to %d in method %s\n",
1173                                                                 array_value.value.constant.value, index_variable, index_context->ranges.zero.lower, index_context->ranges.zero.upper, mono_method_full_name (area->cfg->method, TRUE));
1174                                         }
1175                                         inst->flags |= (MONO_INST_NORANGECHECK);
1176                                 }
1177                         } else if (index_value_kind != MONO_UNKNOWN_INTEGER_VALUE) {
1178                                 /* The index has an unknown but bounded value */
1179                                 MonoRelationsEvaluationRange range;
1180                                 MONO_MAKE_RELATIONS_EVALUATION_RANGE_WEAK (range);
1181                                 apply_value_kind_to_range (&range, index_value_kind);
1182
1183                                 if ((range.lower >= 0) && (range.upper < array_value.value.constant.value)) {
1184                                         if (REPORT_ABC_REMOVAL) {
1185                                                 printf ("ARRAY-ACCESS: removed bounds check on array of constant length %d with unknown index ranging from %d to %d in method %s\n",
1186                                                                 array_value.value.constant.value, range.lower, range.upper, mono_method_full_name (area->cfg->method, TRUE));
1187                                         }
1188                                         inst->flags |= (MONO_INST_NORANGECHECK);
1189                                 }
1190                         }
1191                 }
1192         }
1193 }
1194
1195 /*
1196  * Recursively scan a tree of MonoInst looking for array accesses.
1197  * inst: the root of the MonoInst tree
1198  * area: the current evaluation area (it contains the relation graph and
1199  *       memory for all the evaluation contexts is already allocated)
1200  */
1201 static void
1202 process_inst (MonoInst *inst, MonoVariableRelationsEvaluationArea *area) {
1203         if (inst->opcode == CEE_LDELEMA) { /* Handle OP_LDELEMA2D, too */
1204                 if (TRACE_ABC_REMOVAL) {
1205                         printf ("Attempting check removal...\n");
1206                 }
1207
1208                 remove_abc_from_inst (inst, area);
1209         }
1210
1211         if (mono_burg_arity [inst->opcode]) {
1212                 process_inst (inst->inst_left, area);
1213                 if (mono_burg_arity [inst->opcode] > 1) {
1214                         process_inst (inst->inst_right, area);
1215                 }
1216         }
1217 }
1218
1219
1220
1221
1222 /*
1223  * Process a BB removing bounds checks from array accesses.
1224  * It does the following (in sequence):
1225  * - Get the BB entry condition
1226  * - Add its relations to the relation graph in the evaluation area
1227  * - Process all the MonoInst trees in the BB
1228  * - Recursively process all the children BBs in the dominator tree
1229  * - Remove the relations previously added to the relation graph
1230  *
1231  * bb: the BB that must be processed
1232  * area: the current evaluation area (it contains the relation graph and
1233  *       memory for all the evaluation contexts is already allocated)
1234  */
1235 static void
1236 process_block (MonoBasicBlock *bb, MonoVariableRelationsEvaluationArea *area) {
1237         int inst_index;
1238         MonoInst *current_inst;
1239         MonoAdditionalVariableRelationsForBB additional_relations;
1240         GList *dominated_bb;
1241
1242         if (TRACE_ABC_REMOVAL) {
1243                 printf ("Processing block %d [dfn %d]...\n", bb->block_num, bb->dfn);
1244         }
1245
1246         get_relations_from_previous_bb (area, bb, &additional_relations);
1247         if (TRACE_ABC_REMOVAL) {
1248                 if (additional_relations.relation1.relation.relation != MONO_ANY_RELATION) {
1249                         printf ("Adding relation 1 on variable %d: ", additional_relations.relation1.variable);
1250                         print_summarized_value_relation (&(additional_relations.relation1.relation));
1251                         printf ("\n");
1252                 }
1253                 if (additional_relations.relation2.relation.relation != MONO_ANY_RELATION) {
1254                         printf ("Adding relation 2 on variable %d: ", additional_relations.relation2.variable);
1255                         print_summarized_value_relation (&(additional_relations.relation2.relation));
1256                         printf ("\n");
1257                 }
1258         }
1259         apply_change_to_evaluation_area (area, &(additional_relations.relation1));
1260         apply_change_to_evaluation_area (area, &(additional_relations.relation2));
1261
1262         inst_index = 0;
1263         current_inst = bb->code;
1264         while (current_inst != NULL) {
1265                 if (TRACE_ABC_REMOVAL) {
1266                         printf ("Processing instruction %d\n", inst_index);
1267                         inst_index++;
1268                 }
1269
1270                 process_inst (current_inst, area);
1271
1272                 current_inst = current_inst->next;
1273         }
1274
1275
1276         if (TRACE_ABC_REMOVAL) {
1277                 printf ("Processing block %d [dfn %d] done.\n", bb->block_num, bb->dfn);
1278         }
1279
1280         for (dominated_bb = g_list_first (bb->dominated); dominated_bb != NULL; dominated_bb = g_list_next (dominated_bb)) {
1281                 process_block ((MonoBasicBlock*) (dominated_bb->data), area);
1282         }
1283
1284         remove_change_from_evaluation_area (&(additional_relations.relation1));
1285         remove_change_from_evaluation_area (&(additional_relations.relation2));
1286 }
1287
1288
1289
1290 /**
1291  * mono_perform_abc_removal:
1292  * @cfg: Control Flow Graph
1293  *
1294  * Performs the ABC removal from a cfg in SSA form.
1295  * It does the following:
1296  * - Prepare the evaluation area
1297  * - Allocate memory for the relation graph in the evaluation area
1298  *   (of course, only for variable definitions) and summarize there all
1299  *   variable definitions
1300  * - Allocate memory for the evaluation contexts in the evaluation area
1301  * - Recursively process all the BBs in the dominator tree (it is enough
1302  *   to invoke the processing on the entry BB)
1303  *
1304  * cfg: the method code
1305  */
1306 void
1307 mono_perform_abc_removal (MonoCompile *cfg)
1308 {
1309         MonoVariableRelationsEvaluationArea area;
1310         int i;
1311
1312         verbose_level = cfg->verbose_level;
1313
1314         if (TRACE_ABC_REMOVAL) {
1315                 printf ("Removing array bound checks in %s\n", mono_method_full_name (cfg->method, TRUE));
1316         }
1317
1318         area.cfg = cfg;
1319         area.relations = (MonoSummarizedValueRelation *)
1320                 alloca (sizeof (MonoSummarizedValueRelation) * (cfg->num_varinfo) * 2);
1321         area.contexts = (MonoRelationsEvaluationContext *)
1322                 alloca (sizeof (MonoRelationsEvaluationContext) * (cfg->num_varinfo));
1323         area.variable_value_kind = (MonoIntegerValueKind *)
1324                 alloca (sizeof (MonoIntegerValueKind) * (cfg->num_varinfo));
1325         for (i = 0; i < cfg->num_varinfo; i++) {
1326                 area.variable_value_kind [i] = MONO_UNKNOWN_INTEGER_VALUE;
1327                 area.relations [i].relation = MONO_EQ_RELATION;
1328                 area.relations [i].relation_is_static_definition = TRUE;
1329                 area.relations [i].next = NULL;
1330                 if (cfg->vars [i]->def != NULL) {
1331                         MonoInst *value = get_variable_value_from_store_instruction (cfg->vars [i]->def, i);
1332                         if (value != NULL) {
1333                                 gboolean is_array_type;
1334                                 MonoIntegerValueKind effective_value_kind;
1335                                 MonoRelationsEvaluationRange range;
1336                                 MonoSummarizedValueRelation *type_relation;
1337
1338                                 switch (cfg->varinfo [i]->inst_vtype->type) {
1339                                 case MONO_TYPE_ARRAY:
1340                                 case MONO_TYPE_SZARRAY:
1341                                         is_array_type = TRUE;
1342                                         goto handle_array_value;
1343                                 case MONO_TYPE_OBJECT:
1344                                         is_array_type = FALSE;
1345 handle_array_value:
1346                                         summarize_array_value (&area, value, &(area.relations [i].related_value), is_array_type);
1347                                         if (TRACE_ABC_REMOVAL) {
1348                                                 printf ("Summarized variable %d as array (is_array_type = %s): ", i, (is_array_type?"TRUE":"FALSE"));
1349                                                 print_summarized_value (&(area.relations [i].related_value));
1350                                                 printf ("\n");
1351                                         }
1352                                         break;
1353                                 case MONO_TYPE_I1:
1354                                         area.variable_value_kind [i] = MONO_INTEGER_VALUE_SIZE_1;
1355                                         goto handle_integer_value;
1356                                 case MONO_TYPE_U1:
1357                                         area.variable_value_kind [i] = MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
1358                                         goto handle_integer_value;
1359                                 case MONO_TYPE_I2:
1360                                         area.variable_value_kind [i] = MONO_INTEGER_VALUE_SIZE_2;
1361                                         goto handle_integer_value;
1362                                 case MONO_TYPE_U2:
1363                                         area.variable_value_kind [i] = MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
1364                                         goto handle_integer_value;
1365                                 case MONO_TYPE_I4:
1366                                         area.variable_value_kind [i] = MONO_INTEGER_VALUE_SIZE_4;
1367                                         goto handle_integer_value;
1368                                 case MONO_TYPE_U4:
1369                                         area.variable_value_kind [i] = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
1370                                         goto handle_integer_value;
1371                                 case MONO_TYPE_I:
1372                                         area.variable_value_kind [i] = SIZEOF_VOID_P;
1373                                         goto handle_integer_value;
1374                                 case MONO_TYPE_U:
1375                                         area.variable_value_kind [i] = (MONO_UNSIGNED_VALUE_FLAG|SIZEOF_VOID_P);
1376                                         goto handle_integer_value;
1377                                 case MONO_TYPE_I8:
1378                                         area.variable_value_kind [i] = MONO_INTEGER_VALUE_SIZE_8;
1379                                         goto handle_integer_value;
1380                                 case MONO_TYPE_U8:
1381                                         area.variable_value_kind [i] = MONO_UNSIGNED_INTEGER_VALUE_SIZE_8;
1382 handle_integer_value:
1383                                         effective_value_kind = summarize_integer_value (&area, value, &(area.relations [i].related_value), area.variable_value_kind [i]);
1384                                         MONO_MAKE_RELATIONS_EVALUATION_RANGE_WEAK (range);
1385                                         apply_value_kind_to_range (&range, area.variable_value_kind [i]);
1386                                         apply_value_kind_to_range (&range, effective_value_kind);
1387
1388                                         if (range.upper < INT_MAX) {
1389                                                 type_relation = (MonoSummarizedValueRelation *) alloca (sizeof (MonoSummarizedValueRelation));
1390                                                 type_relation->relation = MONO_LE_RELATION;
1391                                                 type_relation->related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1392                                                 type_relation->related_value.value.constant.value = range.upper;
1393                                                 type_relation->relation_is_static_definition = TRUE;
1394                                                 type_relation->next = area.relations [i].next;
1395                                                 area.relations [i].next = type_relation;
1396                                                 if (TRACE_ABC_REMOVAL) {
1397                                                         printf ("[var%d <= %d]", i, range.upper);
1398                                                 }
1399                                         }
1400                                         if (range.lower > INT_MIN) {
1401                                                 type_relation = (MonoSummarizedValueRelation *) alloca (sizeof (MonoSummarizedValueRelation));
1402                                                 type_relation->relation = MONO_GE_RELATION;
1403                                                 type_relation->related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1404                                                 type_relation->related_value.value.constant.value = range.lower;
1405                                                 type_relation->relation_is_static_definition = TRUE;
1406                                                 type_relation->next = area.relations [i].next;
1407                                                 area.relations [i].next = type_relation;
1408                                                 if (TRACE_ABC_REMOVAL) {
1409                                                         printf ("[var%d >= %d]", i, range.lower);
1410                                                 }
1411                                         }
1412                                         if (TRACE_ABC_REMOVAL) {
1413                                                 printf ("Summarized variable %d: ", i);
1414                                                 print_summarized_value (&(area.relations [i].related_value));
1415                                                 printf ("\n");
1416                                         }
1417                                         break;
1418                                 default:
1419                                         MAKE_VALUE_ANY (area.relations [i].related_value);
1420                                         if (TRACE_ABC_REMOVAL) {
1421                                                 printf ("Variable %d not handled (type %d)\n", i, cfg->varinfo [i]->inst_vtype->type);
1422                                         }
1423                                 }
1424                         } else {
1425                                 MAKE_VALUE_ANY (area.relations [i].related_value);
1426                                 if (TRACE_ABC_REMOVAL) {
1427                                         printf ("Definition of variable %d is not a proper store\n", i);
1428                                 }
1429                         }
1430                 } else {
1431                         MAKE_VALUE_ANY (area.relations [i].related_value);
1432                         if (TRACE_ABC_REMOVAL) {
1433                                 printf ("Variable %d has no definition, probably it is an argument\n", i);
1434                         }
1435                 }
1436         }
1437         for (i = 0; i < cfg->num_varinfo; i++) {
1438                 if (area.relations [i].related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1439                         int related_index = cfg->num_varinfo + i;
1440                         int related_variable = area.relations [i].related_value.value.variable.variable;
1441
1442                         area.relations [related_index].relation = MONO_EQ_RELATION;
1443                         area.relations [related_index].relation_is_static_definition = TRUE;
1444                         area.relations [related_index].related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
1445                         area.relations [related_index].related_value.value.variable.variable = i;
1446                         area.relations [related_index].related_value.value.variable.delta = - area.relations [i].related_value.value.variable.delta;
1447
1448                         area.relations [related_index].next = area.relations [related_variable].next;
1449                         area.relations [related_variable].next = &(area.relations [related_index]);
1450
1451                         if (TRACE_ABC_REMOVAL) {
1452                                 printf ("Added symmetric summarized value for variable variable %d (to %d): ", i, related_variable);
1453                                 print_summarized_value (&(area.relations [related_index].related_value));
1454                                 printf ("\n");
1455                         }
1456                 }
1457         }
1458
1459         process_block (cfg->bblocks [0], &area);
1460 }