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 "config.h"
  17
  18 #ifndef DISABLE_JIT
  19
  20 #ifndef DISABLE_SSA
  21
  22 #include "inssel.h"
  23
  24 #include "abcremoval.h"
  25
  26 #if SIZEOF_VOID_P == 8
  27 #define OP_PCONST OP_I8CONST
  28 #else
  29 #define OP_PCONST OP_ICONST
  30 #endif
  31
  32
  33 #define TRACE_ABC_REMOVAL (verbose_level > 2)
  34 #define REPORT_ABC_REMOVAL (verbose_level > 0)
  35
  36 /*
  37  * A little hack for the verbosity level.
  38  * The verbosity level is stored in the cfg, but not all functions that must
  39  * print something see the cfg, so we store the verbosity level here at the
  40  * beginning of the algorithm.
  41  * This is not thread safe (does not handle correctly different verbosity
  42  * levels in different threads), and is not exact in case of dynamic changes
  43  * of the verbosity level...
  44  * Anyway, this is not needed, all that can happen is that something more
  45  * (or less) is logged, the result is in any case correct.
  46  */
  47 static int verbose_level;
  48
  49
  50 #define RELATION_BETWEEN_VALUES(value,related_value) (\
  51         ((value) > (related_value))? MONO_GT_RELATION :\
  52         (((value) < (related_value))? MONO_LT_RELATION : MONO_EQ_RELATION))
  53
  54 #define MAKE_VALUE_ANY(v) do{\
  55                 (v).type = MONO_ANY_SUMMARIZED_VALUE;\
  56         } while (0)
  57
  58 #define MAKE_VALUE_RELATION_ANY(r) do{\
  59                 (r)->relation = MONO_ANY_RELATION;\
  60                 MAKE_VALUE_ANY((r)->related_value);\
  61         } while (0)
  62
  63 #define INITIALIZE_VALUE_RELATION(r) do{\
  64                 MAKE_VALUE_RELATION_ANY((r));\
  65                 (r)->next = NULL;\
  66         } while (0)
  67
  68 #define MONO_NEGATED_RELATION(r) ((~(r))&MONO_ANY_RELATION)
  69 #define MONO_SYMMETRIC_RELATION(r) (((r)&MONO_EQ_RELATION)|(((r)&MONO_LT_RELATION)<<1)|((r&MONO_GT_RELATION)>>1))
  70
  71
  72
  73 static void
  74 print_relation (int relation) {
  75         int print_or = 0;
  76         printf ("(");
  77         if (relation & MONO_LT_RELATION) {
  78                 printf ("LT");
  79                 print_or = 1;
  80         }
  81         if (relation & MONO_EQ_RELATION) {
  82                 if (print_or) {
  83                         printf ("|");
  84                 }
  85                 printf ("EQ");
  86                 print_or = 1;
  87         }
  88         if (relation & MONO_GT_RELATION) {
  89                 if (print_or) {
  90                         printf ("|");
  91                 }
  92                 printf ("GT");
  93                 print_or = 1;
  94         }
  95         printf (")");
  96 }
  97
  98 static void
  99 print_summarized_value (MonoSummarizedValue *value) {
 100         switch (value->type) {
 101         case MONO_ANY_SUMMARIZED_VALUE:
 102                 printf ("ANY");
 103                 break;
 104         case MONO_CONSTANT_SUMMARIZED_VALUE:
 105                 printf ("CONSTANT %d", value->value.constant.value);
 106                 break;
 107         case MONO_VARIABLE_SUMMARIZED_VALUE:
 108                 printf ("VARIABLE %d, delta %d", value->value.variable.variable, value->value.variable.delta);
 109                 break;
 110         case MONO_PHI_SUMMARIZED_VALUE: {
 111                 int phi;
 112                 printf ("PHI (");
 113                 for (phi = 0; phi < value->value.phi.number_of_alternatives; phi++) {
 114                         if (phi) printf (",");
 115                         printf ("%d", value->value.phi.phi_alternatives [phi]);
 116                 }
 117                 printf (")");
 118                 break;
 119         }
 120         default:
 121                 g_assert_not_reached ();
 122         }
 123 }
 124
 125 static void
 126 print_summarized_value_relation (MonoSummarizedValueRelation *relation) {
 127         printf ("Relation ");
 128         print_relation (relation->relation);
 129         printf (" with value ");
 130         print_summarized_value (&(relation->related_value));
 131 }
 132
 133 #if 0
 134 static void
 135 print_summarized_value_relation_chain (MonoSummarizedValueRelation *relation) {
 136         printf ("Relations:\n");
 137         while (relation) {
 138                 print_summarized_value_relation (relation);
 139                 printf ("\n");
 140                 relation = relation->next;
 141         }
 142 }
 143 #endif
 144
 145 static void
 146 print_evaluation_context_status (MonoRelationsEvaluationStatus status) {
 147         if (status == MONO_RELATIONS_EVALUATION_NOT_STARTED) {
 148                 printf ("EVALUATION_NOT_STARTED");
 149         } else {
 150                 gboolean print_or = FALSE;
 151
 152                 printf ("(");
 153                 if (status & MONO_RELATIONS_EVALUATION_IN_PROGRESS) {
 154                         if (print_or) printf ("|");
 155                         printf ("EVALUATION_IN_PROGRESS");
 156                         print_or = TRUE;
 157                 }
 158                 if (status & MONO_RELATIONS_EVALUATION_COMPLETED) {
 159                         if (print_or) printf ("|");
 160                         printf ("EVALUATION_COMPLETED");
 161                         print_or = TRUE;
 162                 }
 163                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
 164                         if (print_or) printf ("|");
 165                         printf ("RECURSIVELY_ASCENDING");
 166                         print_or = TRUE;
 167                 }
 168                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
 169                         if (print_or) printf ("|");
 170                         printf ("RECURSIVELY_DESCENDING");
 171                         print_or = TRUE;
 172                 }
 173                 if (status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
 174                         if (print_or) printf ("|");
 175                         printf ("RECURSIVELY_INDEFINITE");
 176                         print_or = TRUE;
 177                 }
 178                 printf (")");
 179         }
 180 }
 181
 182
 183 static void
 184 print_evaluation_context_ranges (MonoRelationsEvaluationRanges *ranges) {
 185         printf ("(ranges: zero [%d,%d], variable [%d,%d])", ranges->zero.lower, ranges->zero.upper, ranges->variable.lower, ranges->variable.upper);
 186 }
 187
 188 static void
 189 print_evaluation_context (MonoRelationsEvaluationContext *context) {
 190         printf ("Context status: ");
 191         print_evaluation_context_status (context->status);
 192         if (context->status & (MONO_RELATIONS_EVALUATION_IN_PROGRESS|MONO_RELATIONS_EVALUATION_COMPLETED)) {
 193                 print_evaluation_context_ranges (&(context->ranges));
 194         }
 195         printf ("\n");
 196 }
 197
 198 #if 0
 199 static void
 200 print_evaluation_area (MonoVariableRelationsEvaluationArea *area) {
 201         int i;
 202         printf ("Dump of evaluation area (%d variables):\n", area->cfg->num_varinfo);
 203         for (i = 0; i < area->cfg->num_varinfo; i++) {
 204                 printf ("Variable %d: ", i);
 205                 print_evaluation_context (&(area->contexts [i]));
 206                 print_summarized_value_relation_chain (&(area->relations [i]));
 207         }
 208 }
 209
 210 static void
 211 print_evaluation_area_contexts (MonoVariableRelationsEvaluationArea *area) {
 212         int i;
 213         printf ("Dump of evaluation area contexts (%d variables):\n", area->cfg->num_varinfo);
 214         for (i = 0; i < area->cfg->num_varinfo; i++) {
 215                 printf ("Variable %d: ", i);
 216                 print_evaluation_context (&(area->contexts [i]));
 217         }
 218 }
 219 #endif
 220
 221 /*
 222  * Given a MonoInst, if it is a store to a variable return the MonoInst that
 223  * represents the stored value.
 224  * If anything goes wrong, return NULL.
 225  * store: the MonoInst that should be a store
 226  * expected_variable_index: the variable where the value should be stored
 227  * return: either the stored value, or NULL
 228  */
 229 static MonoInst *
 230 get_variable_value_from_store_instruction (MonoInst *store, int expected_variable_index) {
 231         switch (store->opcode) {
 232         case CEE_STIND_REF:
 233         case CEE_STIND_I:
 234         case CEE_STIND_I4:
 235         case CEE_STIND_I1:
 236         case CEE_STIND_I2:
 237         case CEE_STIND_I8:
 238         case CEE_STIND_R4:
 239         case CEE_STIND_R8:
 240                 if (TRACE_ABC_REMOVAL) {
 241                         printf ("[store instruction found]");
 242                 }
 243                 if ((store->inst_left->opcode == OP_LOCAL) || (store->inst_left->opcode == OP_ARG)) {
 244                         int variable_index = store->inst_left->inst_c0;
 245                         if (TRACE_ABC_REMOVAL) {
 246                                 printf ("[value put in local %d (expected %d)]", variable_index, expected_variable_index);
 247                         }
 248                         if (variable_index == expected_variable_index) {
 249                                 return store->inst_right;
 250                         } else {
 251                                 return NULL;
 252                         }
 253                 }
 254                 else
 255                 {
 256                         return NULL;
 257                 }
 258                 break;
 259         default:
 260                 return NULL;
 261         }
 262 }
 263
 264 /*
 265  * Check if the delta of an integer variable value is safe with respect
 266  * to the variable size in bytes and its kind (signed or unsigned).
 267  * If the delta is not safe, make the value an "any".
 268  */
 269 static void
 270 check_delta_safety (MonoVariableRelationsEvaluationArea *area, MonoSummarizedValue *value) {
 271         if (value->type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 272                 int variable = value->value.variable.variable;
 273                 int delta = value->value.variable.delta;
 274                 if ((area->variable_value_kind [variable]) & MONO_UNSIGNED_VALUE_FLAG) {
 275                         if (delta < 0) {
 276                                 MAKE_VALUE_ANY (*value);
 277                         }
 278                 } else {
 279                         if (((area->variable_value_kind [variable]) & MONO_INTEGER_VALUE_SIZE_BITMASK) < 4) {
 280                                 MAKE_VALUE_ANY (*value);
 281                         } else if (delta > 16) {
 282                                 MAKE_VALUE_ANY (*value);
 283                         }
 284                 }
 285         }
 286 }
 287
 288 /* Prototype, definition comes later */
 289 static void
 290 summarize_array_value (MonoVariableRelationsEvaluationArea *area, MonoInst *value, MonoSummarizedValue *result, gboolean is_array_type);
 291
 292 /*
 293  * Given a MonoInst representing an integer value, store it in "summarized" form.
 294  * result_value_kind: the "expected" kind of result;
 295  * result: the "summarized" value
 296  * returns the "actual" kind of result, if guessable (otherwise MONO_UNKNOWN_INTEGER_VALUE)
 297  */
 298 static MonoIntegerValueKind
 299 summarize_integer_value (MonoVariableRelationsEvaluationArea *area, MonoInst *value, MonoSummarizedValue *result, MonoIntegerValueKind result_value_kind) {
 300         MonoIntegerValueKind value_kind;
 301
 302         if (value->type == STACK_I8) {
 303                 value_kind = MONO_INTEGER_VALUE_SIZE_8;
 304         } else if (value->type == STACK_I4) {
 305                 value_kind = MONO_INTEGER_VALUE_SIZE_4;
 306         } else {
 307                 value_kind = MONO_UNKNOWN_INTEGER_VALUE;
 308         }
 309
 310         switch (value->opcode) {
 311         case OP_ICONST:
 312                 result->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 313                 result->value.constant.value = value->inst_c0;
 314                 break;
 315         case OP_LOCAL:
 316         case OP_ARG:
 317                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 318                 result->value.variable.variable = value->inst_c0;
 319                 result->value.variable.delta = 0;
 320                 value_kind = area->variable_value_kind [value->inst_c0];
 321                 break;
 322         case CEE_LDIND_I1:
 323                 value_kind = MONO_INTEGER_VALUE_SIZE_1;
 324                 goto handle_load;
 325         case CEE_LDIND_U1:
 326                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
 327                 goto handle_load;
 328         case CEE_LDIND_I2:
 329                 value_kind = MONO_INTEGER_VALUE_SIZE_2;
 330                 goto handle_load;
 331         case CEE_LDIND_U2:
 332                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
 333                 goto handle_load;
 334         case CEE_LDIND_I4:
 335                 value_kind = MONO_INTEGER_VALUE_SIZE_4;
 336                 goto handle_load;
 337         case CEE_LDIND_U4:
 338                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
 339                 goto handle_load;
 340         case CEE_LDIND_I8:
 341                 value_kind = MONO_INTEGER_VALUE_SIZE_8;
 342                 goto handle_load;
 343         case CEE_LDIND_I:
 344                 value_kind = SIZEOF_VOID_P;
 345 handle_load:
 346                 if ((value->inst_left->opcode == OP_LOCAL) || (value->inst_left->opcode == OP_ARG)) {
 347                         value_kind = summarize_integer_value (area, value->inst_left, result, result_value_kind);
 348                 } else {
 349                         MAKE_VALUE_ANY (*result);
 350                 }
 351                 break;
 352         case CEE_ADD: {
 353                 MonoSummarizedValue left_value;
 354                 MonoSummarizedValue right_value;
 355                 summarize_integer_value (area, value->inst_left, &left_value, result_value_kind);
 356                 summarize_integer_value (area, value->inst_right, &right_value, result_value_kind);
 357
 358                 if (left_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 359                         if (right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 360                                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 361                                 result->value.variable.variable = left_value.value.variable.variable;
 362                                 result->value.variable.delta = left_value.value.variable.delta + right_value.value.constant.value;
 363                         } else {
 364                                 MAKE_VALUE_ANY (*result);
 365                         }
 366                 } else if (right_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 367                         if (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 368                                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 369                                 result->value.variable.variable = right_value.value.variable.variable;
 370                                 result->value.variable.delta = left_value.value.constant.value + right_value.value.variable.delta;
 371                         } else {
 372                                 MAKE_VALUE_ANY (*result);
 373                         }
 374                 } else if ((right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) && (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE)) {
 375                         /* This should not happen if constant folding has been done */
 376                         result->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 377                         result->value.constant.value = left_value.value.constant.value + right_value.value.constant.value;
 378                 } else {
 379                         MAKE_VALUE_ANY (*result);
 380                 }
 381                 if (result->type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 382                         check_delta_safety (area, result);
 383                 }
 384                 break;
 385         }
 386         case CEE_SUB: {
 387                 MonoSummarizedValue left_value;
 388                 MonoSummarizedValue right_value;
 389                 summarize_integer_value (area, value->inst_left, &left_value, result_value_kind);
 390                 summarize_integer_value (area, value->inst_right, &right_value, result_value_kind);
 391
 392                 if (left_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 393                         if (right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 394                                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 395                                 result->value.variable.variable = left_value.value.variable.variable;
 396                                 result->value.variable.delta = left_value.value.variable.delta - right_value.value.constant.value;
 397                         } else {
 398                                 MAKE_VALUE_ANY (*result);
 399                         }
 400                 } else if ((right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) && (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE)) {
 401                         /* This should not happen if constant folding has been done */
 402                         result->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 403                         result->value.constant.value = left_value.value.constant.value - right_value.value.constant.value;
 404                 } else {
 405                         MAKE_VALUE_ANY (*result);
 406                 }
 407                 if (result->type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 408                         check_delta_safety (area, result);
 409                 }
 410                 break;
 411         }
 412         case CEE_AND: {
 413                 MonoSummarizedValue left_value;
 414                 MonoSummarizedValue right_value;
 415                 int constant_operand_value;
 416
 417                 summarize_integer_value (area, value->inst_left, &left_value, result_value_kind);
 418                 summarize_integer_value (area, value->inst_right, &right_value, result_value_kind);
 419
 420                 if (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 421                         constant_operand_value = left_value.value.constant.value;
 422                 } else if (right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 423                         constant_operand_value = right_value.value.constant.value;
 424                 } else {
 425                         constant_operand_value = 0;
 426                 }
 427
 428                 if (constant_operand_value > 0) {
 429                         if (constant_operand_value <= 0xff) {
 430                                 if ((result_value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) > 1) {
 431                                         value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
 432                                 }
 433                         } else if (constant_operand_value <= 0xffff) {
 434                                 if ((result_value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) > 2) {
 435                                         value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
 436                                 }
 437                         }
 438                 }
 439
 440                 MAKE_VALUE_ANY (*result);
 441                 break;
 442         }
 443         case CEE_CONV_I1:
 444         case CEE_CONV_OVF_I1:
 445         case CEE_CONV_OVF_I1_UN:
 446                 value_kind = MONO_INTEGER_VALUE_SIZE_1;
 447                 MAKE_VALUE_ANY (*result);
 448                 break;
 449         case CEE_CONV_U1:
 450         case CEE_CONV_OVF_U1:
 451                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
 452                 MAKE_VALUE_ANY (*result);
 453                 break;
 454         case CEE_CONV_I2:
 455         case CEE_CONV_OVF_I2:
 456         case CEE_CONV_OVF_I2_UN:
 457                 value_kind = MONO_INTEGER_VALUE_SIZE_2;
 458                 MAKE_VALUE_ANY (*result);
 459                 break;
 460         case CEE_CONV_U2:
 461         case CEE_CONV_OVF_U2:
 462                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
 463                 MAKE_VALUE_ANY (*result);
 464                 break;
 465         case CEE_LDLEN:
 466                 summarize_array_value (area, value->inst_left, result, TRUE);
 467                 value_kind = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
 468                 break;
 469         case OP_LCONV_TO_I4:
 470                 value_kind = summarize_integer_value (area, value->inst_left, result, result_value_kind);
 471                 break;
 472         case OP_PHI:
 473                 result->type = MONO_PHI_SUMMARIZED_VALUE;
 474                 result->value.phi.number_of_alternatives = *(value->inst_phi_args);
 475                 result->value.phi.phi_alternatives = value->inst_phi_args + 1;
 476                 break;
 477         default:
 478                 MAKE_VALUE_ANY (*result);
 479         }
 480         return value_kind;
 481 }
 482
 483 /*
 484  * Given a MonoInst representing an array value, store it in "summarized" form.
 485  * result: the "summarized" value
 486  * is_array_type: TRUE of we are *sure* that an eventual OP_PCONST will point
 487  * to a MonoArray (this can happen for already initialized readonly static fields,
 488  * in which case we will get the array length directly from the MonoArray)
 489  */
 490 static void
 491 summarize_array_value (MonoVariableRelationsEvaluationArea *area, MonoInst *value, MonoSummarizedValue *result, gboolean is_array_type) {
 492         switch (value->opcode) {
 493         case OP_LOCAL:
 494         case OP_ARG:
 495                 result->type = MONO_VARIABLE_SUMMARIZED_VALUE;
 496                 result->value.variable.variable = value->inst_c0;
 497                 result->value.variable.delta = 0;
 498                 break;
 499         case CEE_LDIND_REF:
 500                 summarize_array_value (area, value->inst_left, result, FALSE);
 501                 break;
 502         case CEE_NEWARR:
 503                 summarize_integer_value (area, value->inst_newa_len, result, MONO_UNKNOWN_INTEGER_VALUE);
 504                 break;
 505         case OP_PCONST:
 506                 if ((is_array_type) && (value->inst_p0 != NULL)) {
 507                         MonoArray *array = (MonoArray *) (value->inst_p0);
 508                         result->type = MONO_CONSTANT_SUMMARIZED_VALUE;
 509                         result->value.constant.value = array->max_length;
 510                 } else {
 511                         MAKE_VALUE_ANY (*result);
 512                 }
 513                 break;
 514         case OP_PHI:
 515                 result->type = MONO_PHI_SUMMARIZED_VALUE;
 516                 result->value.phi.number_of_alternatives = *(value->inst_phi_args);
 517                 result->value.phi.phi_alternatives = value->inst_phi_args + 1;
 518                 break;
 519         default:
 520                 MAKE_VALUE_ANY (*result);
 521         }
 522 }
 523
 524 static MonoValueRelation
 525 get_relation_from_branch_instruction (int opcode) {
 526         switch (opcode) {
 527         case CEE_BEQ:
 528                 return MONO_EQ_RELATION;
 529         case CEE_BLT:
 530         case CEE_BLT_UN:
 531                 return MONO_LT_RELATION;
 532         case CEE_BLE:
 533         case CEE_BLE_UN:
 534                 return MONO_LE_RELATION;
 535         case CEE_BGT:
 536         case CEE_BGT_UN:
 537                 return MONO_GT_RELATION;
 538         case CEE_BGE:
 539         case CEE_BGE_UN:
 540                 return MONO_GE_RELATION;
 541         case CEE_BNE_UN:
 542                 return MONO_NE_RELATION;
 543         default:
 544                 return MONO_ANY_RELATION;
 545         }
 546 }
 547
 548 /*
 549  * Given a BB, find its entry condition and put its relations in a
 550  * "MonoAdditionalVariableRelationsForBB" structure.
 551  * bb: the BB
 552  * relations: the resulting relations (entry condition of the given BB)
 553  */
 554 static void
 555 get_relations_from_previous_bb (MonoVariableRelationsEvaluationArea *area, MonoBasicBlock *bb, MonoAdditionalVariableRelationsForBB *relations) {
 556         MonoBasicBlock *in_bb;
 557         MonoInst *branch;
 558         MonoValueRelation branch_relation;
 559         MonoValueRelation symmetric_relation;
 560
 561         INITIALIZE_VALUE_RELATION (&(relations->relation1.relation));
 562         relations->relation1.relation.relation_is_static_definition = FALSE;
 563         relations->relation1.insertion_point = NULL;
 564         relations->relation1.variable = -1;
 565         INITIALIZE_VALUE_RELATION (&(relations->relation2.relation));
 566         relations->relation2.relation.relation_is_static_definition = FALSE;
 567         relations->relation2.insertion_point = NULL;
 568         relations->relation2.variable = -1;
 569
 570
 571         if (bb->in_count == 1) { /* Should write the code to "sum" conditions... */
 572                 in_bb = bb->in_bb [0];
 573                 branch = in_bb->last_ins;
 574                 if (branch == NULL) return;
 575                 branch_relation = get_relation_from_branch_instruction (branch->opcode);
 576                 if ((branch_relation != MONO_ANY_RELATION) && (branch->inst_left->opcode == OP_COMPARE)) {
 577                         MonoSummarizedValue left_value;
 578                         MonoSummarizedValue right_value;
 579                         gboolean code_path;
 580
 581                         if (branch->inst_true_bb == bb) {
 582                                 code_path = TRUE;
 583                         } else if (branch->inst_false_bb == bb) {
 584                                 code_path = FALSE;
 585                         } else {
 586                                 code_path = TRUE;
 587                                 g_assert_not_reached ();
 588                         }
 589
 590                         if (!code_path) {
 591                                 branch_relation = MONO_NEGATED_RELATION (branch_relation);
 592                         }
 593                         symmetric_relation = MONO_SYMMETRIC_RELATION (branch_relation);
 594
 595                         summarize_integer_value (area, branch->inst_left->inst_left, &left_value, MONO_UNKNOWN_INTEGER_VALUE);
 596                         summarize_integer_value (area, branch->inst_left->inst_right, &right_value, MONO_UNKNOWN_INTEGER_VALUE);
 597
 598                         if ((left_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) && ((right_value.type == MONO_VARIABLE_SUMMARIZED_VALUE)||(right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE))) {
 599                                 relations->relation1.variable = left_value.value.variable.variable;
 600                                 relations->relation1.relation.relation = branch_relation;
 601                                 relations->relation1.relation.related_value = right_value;
 602                                 if (right_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 603                                         relations->relation1.relation.related_value.value.constant.value -= left_value.value.variable.delta;
 604                                 } else {
 605                                         relations->relation1.relation.related_value.value.variable.delta -= left_value.value.variable.delta;
 606                                 }
 607                         }
 608                         if ((right_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) && ((left_value.type == MONO_VARIABLE_SUMMARIZED_VALUE)||(left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE))) {
 609                                 relations->relation2.variable = right_value.value.variable.variable;
 610                                 relations->relation2.relation.relation = symmetric_relation;
 611                                 relations->relation2.relation.related_value = left_value;
 612                                 if (left_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
 613                                         relations->relation2.relation.related_value.value.constant.value -= right_value.value.variable.delta;
 614                                 } else {
 615                                         relations->relation2.relation.related_value.value.variable.delta -= right_value.value.variable.delta;
 616                                 }
 617                         }
 618                 }
 619         }
 620 }
 621
 622
 623 /*
 624  * Add the given relations to the evaluation area.
 625  * area: the evaluation area
 626  * change: the relations that must be added
 627  */
 628 static void
 629 apply_change_to_evaluation_area (MonoVariableRelationsEvaluationArea *area, MonoAdditionalVariableRelation *change) {
 630         MonoSummarizedValueRelation *base_relation;
 631
 632         if (change->relation.relation != MONO_ANY_RELATION) {
 633                 base_relation = &(area->relations [change->variable]);
 634                 while ((base_relation->next != NULL) && (base_relation->next->relation_is_static_definition)) {
 635                         base_relation = base_relation->next;
 636                 }
 637                 change->insertion_point = base_relation;
 638                 change->relation.next = base_relation->next;
 639                 base_relation->next = &(change->relation);
 640         }
 641 }
 642
 643 /*
 644  * Remove the given relation from the evaluation area.
 645  * change: the relation that must be removed
 646  */
 647 static void
 648 remove_change_from_evaluation_area (MonoAdditionalVariableRelation *change) {
 649         if (change->insertion_point != NULL) {
 650                 change->insertion_point->next = change->relation.next;
 651                 change->relation.next = NULL;
 652         }
 653 }
 654
 655
 656 static void
 657 clean_contexts (MonoRelationsEvaluationContext *contexts, int number) {
 658         int i;
 659         for (i = 0; i < number; i++) {
 660                 contexts [i].status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
 661         }
 662 }
 663
 664
 665 /*
 666  * Perform the intersection of a range and a constant value (taking into
 667  * account the relation that the value has with the range).
 668  * range: the range that will be intersected with the value
 669  * value: the value that will be intersected with the range
 670  * relation: the relation between the range and the value
 671  */
 672 static void
 673 intersect_value( MonoRelationsEvaluationRange *range, int value, MonoValueRelation relation ) {
 674         switch (relation) {
 675         case MONO_NO_RELATION:
 676                 MONO_MAKE_RELATIONS_EVALUATION_RANGE_IMPOSSIBLE (*range);
 677                 break;
 678         case MONO_ANY_RELATION:
 679                 break;
 680         case MONO_EQ_RELATION:
 681                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
 682                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
 683                 break;
 684         case MONO_NE_RELATION: {
 685                 /* IMPROVEMENT Figure this out! (ignoring it is safe anyway) */
 686                 break;
 687         }
 688         case MONO_LT_RELATION:
 689                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (value));
 690                 break;
 691         case MONO_LE_RELATION:
 692                 MONO_UPPER_EVALUATION_RANGE_INTERSECTION (range->upper, value);
 693                 break;
 694         case MONO_GT_RELATION:
 695                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (value));
 696                 break;
 697         case MONO_GE_RELATION:
 698                 MONO_LOWER_EVALUATION_RANGE_INTERSECTION (range->lower, value);
 699                 break;
 700         default:
 701                 g_assert_not_reached();
 702         }
 703 }
 704
 705
 706 /*
 707  * Perform the intersection of two pairs of ranges (taking into account the
 708  * relation between the ranges and a given delta).
 709  * ranges: the ranges that will be intersected
 710  * other_ranges the other ranges that will be intersected
 711  * delta: the delta between the pairs of ranges
 712  * relation: the relation between the pairs of ranges
 713  */
 714 static void
 715 intersect_ranges( MonoRelationsEvaluationRanges *ranges, MonoRelationsEvaluationRanges *other_ranges, int delta, MonoValueRelation relation ) {
 716         if (delta == 0) {
 717                 switch (relation) {
 718                 case MONO_NO_RELATION:
 719                         MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (*ranges);
 720                         break;
 721                 case MONO_ANY_RELATION:
 722                         break;
 723                 case MONO_EQ_RELATION:
 724                         MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (*ranges, *other_ranges);
 725                         break;
 726                 case MONO_NE_RELATION: {
 727                         /* FIXME Figure this out! (ignoring it is safe anyway) */
 728                         break;
 729                 }
 730                 case MONO_LT_RELATION:
 731                         MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->zero.upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->zero.upper));
 732                         MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->variable.upper, MONO_UPPER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->variable.upper));
 733                         break;
 734                 case MONO_LE_RELATION:
 735                         MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->zero.upper, other_ranges->zero.upper);
 736                         MONO_UPPER_EVALUATION_RANGE_INTERSECTION (ranges->variable.upper, other_ranges->variable.upper);
 737                         break;
 738                 case MONO_GT_RELATION:
 739                         MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->zero.lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->zero.lower));
 740                         MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->variable.lower, MONO_LOWER_EVALUATION_RANGE_NOT_EQUAL (other_ranges->variable.lower));
 741                         break;
 742                 case MONO_GE_RELATION:
 743                         MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->zero.lower, other_ranges->zero.lower);
 744                         MONO_LOWER_EVALUATION_RANGE_INTERSECTION (ranges->variable.lower, other_ranges->variable.lower);
 745                         break;
 746                 default:
 747                         g_assert_not_reached();
 748                 }
 749         } else {
 750                 MonoRelationsEvaluationRanges translated_ranges = *other_ranges;
 751                 MONO_ADD_DELTA_SAFELY_TO_RANGES (translated_ranges, delta);
 752                 intersect_ranges( ranges, &translated_ranges, FALSE, relation );
 753         }
 754 }
 755
 756 /*
 757  * Recursive method that traverses the relation graph to evaluate the
 758  * relation between two variables.
 759  * At the end of the execution, the resulting ranges are in the context of
 760  * the "starting" variable.
 761  * area: the current evaluation area (it contains the relation graph and
 762  *       memory for all the evaluation contexts is already allocated)
 763  * variable: starting variable (the value ranges in its context are the result
 764  *           of the execution of this procedure)
 765  * target_variable: the variable with respect to which the starting variable
 766  *                  is evaluated (tipically the starting variable is the index
 767  *                  and the target one is the array (which means its length))
 768  * father_context: the previous evaluation context in recursive invocations
 769  *                 (or NULL for the first invocation)
 770  */
 771 static void
 772 evaluate_relation_with_target_variable (MonoVariableRelationsEvaluationArea *area, int variable, int target_variable, MonoRelationsEvaluationContext *father_context) {
 773         MonoRelationsEvaluationContext *context = &(area->contexts [variable]);
 774
 775         // First of all, we check the evaluation status
 776         // (what must be done is *very* different in each case)
 777         switch (context->status) {
 778         case MONO_RELATIONS_EVALUATION_NOT_STARTED: {
 779                 MonoSummarizedValueRelation *relation = &(area->relations [variable]);
 780
 781                 if (TRACE_ABC_REMOVAL) {
 782                         printf ("Evaluating varible %d (target variable %d)\n", variable, target_variable);
 783                         print_summarized_value_relation (relation);
 784                         printf ("\n");
 785                 }
 786
 787                 // We properly inizialize the context
 788                 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
 789                 context->father = father_context;
 790                 MONO_MAKE_RELATIONS_EVALUATION_RANGES_WEAK (context->ranges);
 791
 792                 // If we have found the target variable, we can set the range
 793                 // related to it in the context to "equal" (which is [0,0])
 794                 if (variable == target_variable) {
 795                         if (TRACE_ABC_REMOVAL) {
 796                                 printf ("Target variable reached (%d), continuing to evaluate relations with constants\n", variable);
 797                         }
 798                         context->ranges.variable.lower = 0;
 799                         context->ranges.variable.upper = 0;
 800                 }
 801
 802                 // Examine all relations for this variable (scan the list)
 803                 // The contribute of each relation will be intersected (logical and)
 804                 while (relation != NULL) {
 805                         context->current_relation = relation;
 806
 807                         if (TRACE_ABC_REMOVAL) {
 808                                 printf ("Processing (%d): ", variable);
 809                                 print_summarized_value_relation (relation);
 810                                 printf ("\n");
 811                         }
 812
 813                         // We decie what to do according the the type of the related value
 814                         switch (relation->related_value.type) {
 815                         case MONO_ANY_SUMMARIZED_VALUE:
 816                                 // No added information, skip it
 817                                 break;
 818                         case MONO_CONSTANT_SUMMARIZED_VALUE:
 819                                 // Intersect range with constant (taking into account the relation)
 820                                 intersect_value (&(context->ranges.zero), relation->related_value.value.constant.value, relation->relation);
 821                                 break;
 822                         case MONO_VARIABLE_SUMMARIZED_VALUE:
 823                                 // Generally, evaluate related variable and intersect ranges.
 824                                 // However, some check is necessary...
 825
 826                                 // If the relation is "ANY", nothing to do (no added information)
 827                                 if (relation->relation != MONO_ANY_RELATION) {
 828                                         int related_variable = relation->related_value.value.variable.variable;
 829                                         MonoRelationsEvaluationContext *related_context = &(area->contexts [related_variable]);
 830
 831                                         // The second condition in the "or" avoids messing with "back edges" in the graph traversal
 832                                         // (they are simply ignored instead of triggering the handling of recursion)
 833                                         if ( (related_context->status == MONO_RELATIONS_EVALUATION_NOT_STARTED) || !
 834                                                         ((related_context->current_relation->related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) &&
 835                                                         (related_context->current_relation->related_value.value.variable.variable == variable))) {
 836                                                 // Evaluate the related variable
 837                                                 evaluate_relation_with_target_variable (area, related_variable, target_variable, context);
 838
 839                                                 // Check if we are part of a recursive loop
 840                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
 841                                                         if (TRACE_ABC_REMOVAL) {
 842                                                                 printf ("Recursivity detected for varible %d (target variable %d), status ", variable, target_variable);
 843                                                                 print_evaluation_context_status (context->status);
 844                                                         }
 845
 846                                                         // If we are, check if the evaluation of the related variable is complete
 847                                                         if (related_context->status == MONO_RELATIONS_EVALUATION_COMPLETED) {
 848                                                                 // If it is complete, we are part of a recursive definition.
 849                                                                 // Since it is a *definition* (and definitions are evaluated *before*
 850                                                                 // conditions because they are first in the list), intersection is not
 851                                                                 // strictly necessary, we simply copy the ranges and apply the delta
 852                                                                 context->ranges = related_context->ranges;
 853                                                                 /* Delta has already been checked for over/under-flow when evaluating values */
 854                                                                 MONO_ADD_DELTA_SAFELY_TO_RANGES (context->ranges, relation->related_value.value.variable.delta);
 855                                                                 context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
 856                                                                 if (TRACE_ABC_REMOVAL) {
 857                                                                         printf (", ranges already computed, result: \n");
 858                                                                         print_evaluation_context_ranges (&(context->ranges));
 859                                                                         printf (" (delta is %d)\n", relation->related_value.value.variable.delta);
 860                                                                 }
 861                                                         } else {
 862                                                                 // If it is not complete, do nothing (we do not have enough information)
 863                                                                 if (TRACE_ABC_REMOVAL) {
 864                                                                         printf (", ranges not computed\n");
 865                                                                 }
 866                                                         }
 867                                                 } else {
 868                                                         // If we are not (the common case) intersect the result
 869                                                         intersect_ranges( &(context->ranges), &(related_context->ranges), relation->related_value.value.variable.delta, relation->relation );
 870                                                 }
 871                                         } else {
 872                                                 if (TRACE_ABC_REMOVAL) {
 873                                                         printf ("Relation is a back-edge in this traversal, skipping\n");
 874                                                 }
 875                                         }
 876                                 }
 877                                 break;
 878                         case MONO_PHI_SUMMARIZED_VALUE: {
 879                                 // We must compute all PHI alternatives, combining the results (with a union, which is a logical "or"),
 880                                 // and intersect this result with the ranges in the context; we must also take into account recursions
 881                                 // (with loops that can be ascending, descending, or indefinite)
 882                                 MonoRelationsEvaluationRanges phi_ranges;
 883                                 int phi;
 884                                 gboolean is_ascending = FALSE;
 885                                 gboolean is_descending = FALSE;
 886
 887                                 MONO_MAKE_RELATIONS_EVALUATION_RANGES_IMPOSSIBLE (phi_ranges);
 888                                 for (phi = 0; phi < relation->related_value.value.phi.number_of_alternatives; phi++) {
 889                                         int phi_alternative = relation->related_value.value.phi.phi_alternatives [phi];
 890                                         evaluate_relation_with_target_variable (area, phi_alternative, target_variable, context);
 891
 892                                         // This means we are part of a recursive loop
 893                                         if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
 894                                                 if (TRACE_ABC_REMOVAL) {
 895                                                         printf ("Recursivity detected for varible %d (target variable %d), status ", variable, target_variable);
 896                                                         print_evaluation_context_status (context->status);
 897                                                         printf ("\n");
 898                                                 }
 899                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING) {
 900                                                         is_ascending = TRUE;
 901                                                 }
 902                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING) {
 903                                                         is_descending = TRUE;
 904                                                 }
 905                                                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE) {
 906                                                         is_ascending = TRUE;
 907                                                         is_descending = TRUE;
 908                                                 }
 909
 910                                                 // Clear "recursivity" bits in the status (recursion has been handled)
 911                                                 context->status = MONO_RELATIONS_EVALUATION_IN_PROGRESS;
 912                                         } else {
 913                                                 MONO_RELATIONS_EVALUATION_RANGES_UNION (phi_ranges, area->contexts [phi_alternative].ranges);
 914                                         }
 915                                 }
 916
 917                                 // Apply the effects of all recursive loops
 918                                 if (is_ascending) {
 919                                         phi_ranges.zero.upper = INT_MAX;
 920                                         phi_ranges.variable.upper = INT_MAX;
 921                                 }
 922                                 if (is_descending) {
 923                                         phi_ranges.zero.lower = INT_MIN;
 924                                         phi_ranges.variable.lower = INT_MIN;
 925                                 }
 926
 927                                 // Intersect final result
 928                                 MONO_RELATIONS_EVALUATION_RANGES_INTERSECTION (context->ranges, phi_ranges);
 929                                 break;
 930                         }
 931                         default:
 932                                 g_assert_not_reached();
 933                         }
 934
 935                         // Pass to next relation
 936                         relation = relation->next;
 937                 }
 938
 939                 // Check if any recursivity bits are still in the status, and in any case clear them
 940                 if (context->status & MONO_RELATIONS_EVALUATION_IS_RECURSIVE) {
 941                         if (TRACE_ABC_REMOVAL) {
 942                                 printf ("Recursivity for varible %d (target variable %d) discards computation, status ", variable, target_variable);
 943                                 print_evaluation_context_status (context->status);
 944                                 printf ("\n");
 945                         }
 946                         // If yes, we did not have enough information (most likely we were evaluated inside a PHI, but we also
 947                         // depended on the same PHI, which was still in evaluation...), so clear the status to "NOT_STARTED"
 948                         // (if we will be evaluated again, the PHI will be already done, so our evaluation will succeed)
 949                         context->status = MONO_RELATIONS_EVALUATION_NOT_STARTED;
 950                 } else {
 951                         if (TRACE_ABC_REMOVAL) {
 952                                 printf ("Ranges for varible %d (target variable %d) computed: ", variable, target_variable);
 953                                 print_evaluation_context_ranges (&(context->ranges));
 954                                 printf ("\n");
 955                         }
 956                         // If not (the common case) the evaluation is complete, and the result is in the context
 957                         context->status = MONO_RELATIONS_EVALUATION_COMPLETED;
 958                 }
 959                 break;
 960         }
 961         case MONO_RELATIONS_EVALUATION_IN_PROGRESS: {
 962                 // This means we are in a recursive loop
 963                 MonoRelationsEvaluationContext *current_context = father_context;
 964                 MonoRelationsEvaluationContext *last_context = context->father;
 965                 gboolean evaluation_can_be_recursive = TRUE;
 966                 gboolean evaluation_is_definition = TRUE;
 967                 int path_value = 0;
 968
 969                 if (TRACE_ABC_REMOVAL) {
 970                         printf ("Evaluation of varible %d (target variable %d) already in progress\n", variable, target_variable);
 971                         print_evaluation_context (context);
 972                         print_summarized_value_relation (context->current_relation);
 973                         printf ("\n");
 974                 }
 975
 976                 // We must check if the loop can be a recursive definition (we scan the whole loop)
 977                 while (current_context != last_context) {
 978                         if (current_context == NULL) {
 979                                 printf ("Broken recursive ring in ABC removal\n");
 980                                 g_assert_not_reached ();
 981                         }
 982
 983                         if (current_context->current_relation->relation_is_static_definition) {
 984                                 if (current_context->current_relation->related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
 985                                         /* No need to check path_value for over/under-flow, since delta should be safe */
 986                                         path_value += current_context->current_relation->related_value.value.variable.delta;
 987                                 } else if (current_context->current_relation->related_value.type != MONO_PHI_SUMMARIZED_VALUE) {
 988                                         evaluation_can_be_recursive = FALSE;
 989                                 }
 990                         } else {
 991                                 evaluation_is_definition = FALSE;
 992                                 evaluation_can_be_recursive = FALSE;
 993                         }
 994
 995                         current_context = current_context->father;
 996                 }
 997
 998                 // If this is a recursive definition, we properly flag the status in all the involved contexts
 999                 if (evaluation_is_definition) {
1000                         MonoRelationsEvaluationStatus recursive_status;
1001                         if (evaluation_can_be_recursive) {
1002                                 if (path_value > 0) {
1003                                         recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_ASCENDING;
1004                                 } else if (path_value < 0) {
1005                                         recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_DESCENDING;
1006                                 } else {
1007                                         recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
1008                                 }
1009                         } else {
1010                                 recursive_status = MONO_RELATIONS_EVALUATION_IS_RECURSIVELY_INDEFINITE;
1011                         }
1012
1013                         if (TRACE_ABC_REMOVAL) {
1014                                 printf ("Recursivity accepted (");
1015                                 print_evaluation_context_status (recursive_status);
1016                                 printf (")\n");
1017                         }
1018
1019                         current_context = father_context;
1020                         while (current_context != last_context) {
1021                                 current_context->status |= recursive_status;
1022                                 current_context = current_context->father;
1023                         }
1024                 } else {
1025                         if (TRACE_ABC_REMOVAL) {
1026                                 printf ("Recursivity rejected (some relation in the cycle is not a defintion)\n");
1027                         }
1028                 }
1029                 break;
1030         }
1031         case MONO_RELATIONS_EVALUATION_COMPLETED: {
1032                 return;
1033         }
1034         default:
1035                 if (TRACE_ABC_REMOVAL) {
1036                         printf ("Varible %d (target variable %d) already in a recursive ring, skipping\n", variable, target_variable);
1037                         print_evaluation_context (context);
1038                         print_summarized_value_relation (context->current_relation);
1039                         printf ("\n");
1040                 }
1041                 break;
1042         }
1043
1044 }
1045
1046 /*
1047  * Apply the given value kind to the given range
1048  */
1049 static void apply_value_kind_to_range (MonoRelationsEvaluationRange *range, MonoIntegerValueKind value_kind) {
1050         if (value_kind != MONO_UNKNOWN_INTEGER_VALUE) {
1051                 if (value_kind & MONO_UNSIGNED_VALUE_FLAG) {
1052                         if (range->lower < 0) {
1053                                 range->lower = 0;
1054                         }
1055                         if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
1056                                 if (range->upper > 0xff) {
1057                                         range->upper = 0xff;
1058                                 }
1059                         } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
1060                                 if (range->upper > 0xffff) {
1061                                         range->upper = 0xffff;
1062                                 }
1063                         }
1064                 } else {
1065                         if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 1) {
1066                                 if (range->lower < -0x80) {
1067                                         range->lower = -0x80;
1068                                 }
1069                                 if (range->upper > 0x7f) {
1070                                         range->upper = 0x7f;
1071                                 }
1072                         } else if ((value_kind & MONO_INTEGER_VALUE_SIZE_BITMASK) == 2) {
1073                                 if (range->lower < -0x8000) {
1074                                         range->lower = -0x8000;
1075                                 }
1076                                 if (range->upper > 0x7fff) {
1077                                         range->upper = 0x7fff;
1078                                 }
1079                         }
1080                 }
1081         }
1082 }
1083
1084 /*
1085  * Attempt the removal of bounds checks from a MonoInst.
1086  * inst: the MonoInst
1087  * area: the current evaluation area (it contains the relation graph and
1088  *       memory for all the evaluation contexts is already allocated)
1089  */
1090 static void
1091 remove_abc_from_inst (MonoInst *inst, MonoVariableRelationsEvaluationArea *area) {
1092         if (inst->opcode == CEE_LDELEMA) {
1093                 MonoInst *array_inst = inst->inst_left;
1094                 MonoInst *index_inst = inst->inst_right;
1095                 MonoSummarizedValue array_value;
1096                 MonoSummarizedValue index_value;
1097                 MonoIntegerValueKind index_value_kind;
1098
1099                 /* First of all, examine the CEE_LDELEMA operands */
1100                 summarize_array_value (area, array_inst, &array_value, TRUE);
1101                 index_value_kind = summarize_integer_value (area, index_inst, &index_value, MONO_UNKNOWN_INTEGER_VALUE);
1102
1103                 /* If the array is a local variable... */
1104                 if (array_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1105                         int array_variable = array_value.value.variable.variable;
1106                         MonoRelationsEvaluationContext *array_context = &(area->contexts [array_variable]);
1107
1108                         if (index_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
1109                                 // The easiest case: we just evaluate the array length, to see if it has some relation
1110                                 // with the index constant, and act accordingly
1111
1112                                 clean_contexts (area->contexts, area->cfg->num_varinfo);
1113                                 evaluate_relation_with_target_variable (area, array_variable, array_variable, NULL);
1114
1115                                 if ((index_value.value.constant.value >= 0) && (index_value.value.constant.value < array_context->ranges.zero.lower)) {
1116                                         if (REPORT_ABC_REMOVAL) {
1117                                                 printf ("ARRAY-ACCESS: removed bounds check on array %d with constant index %d in method %s\n",
1118                                                                 array_variable, index_value.value.constant.value, mono_method_full_name (area->cfg->method, TRUE));
1119                                         }
1120                                         inst->flags |= (MONO_INST_NORANGECHECK);
1121                                 }
1122                         } else if (index_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1123                                 // The common case: we must evaluate both the index and the array length, and check for relevant
1124                                 // relations both through variable definitions and as constant definitions
1125
1126                                 int index_variable = index_value.value.variable.variable;
1127                                 MonoRelationsEvaluationContext *index_context = &(area->contexts [index_variable]);
1128
1129                                 clean_contexts (area->contexts, area->cfg->num_varinfo);
1130
1131                                 evaluate_relation_with_target_variable (area, index_variable, array_variable, NULL);
1132                                 evaluate_relation_with_target_variable (area, array_variable, array_variable, NULL);
1133
1134                                 MONO_SUB_DELTA_SAFELY_FROM_RANGES (index_context->ranges, index_value.value.variable.delta);
1135                                 /* Apply index value kind */
1136                                 apply_value_kind_to_range (&(index_context->ranges.zero), index_value_kind);
1137
1138                                 if (index_context->ranges.zero.lower >= 0) {
1139                                         if (TRACE_ABC_REMOVAL) {
1140                                                 printf ("ARRAY-ACCESS: Removed lower bound check on array %d with index %d\n", array_variable, index_variable);
1141                                         }
1142                                         if ((index_context->ranges.variable.upper < 0)||(index_context->ranges.zero.upper < array_context->ranges.zero.lower)) {
1143                                                 if (REPORT_ABC_REMOVAL) {
1144                                                         printf ("ARRAY-ACCESS: removed bounds check on array %d with index %d in method %s\n",
1145                                                                         array_variable, index_variable, mono_method_full_name (area->cfg->method, TRUE));
1146                                                 }
1147                                                 inst->flags |= (MONO_INST_NORANGECHECK);
1148                                         }
1149                                 }
1150                                 if (TRACE_ABC_REMOVAL) {
1151                                         if (index_context->ranges.variable.upper < 0) {
1152                                                 printf ("ARRAY-ACCESS: Removed upper bound check (through variable) on array %d with index %d\n", array_variable, index_variable);
1153                                         }
1154                                         if (index_context->ranges.zero.upper < array_context->ranges.zero.lower) {
1155                                                 printf ("ARRAY-ACCESS: Removed upper bound check (through constant) on array %d with index %d\n", array_variable, index_variable);
1156                                         }
1157                                 }
1158                         }
1159                 } else if (array_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
1160                         if (index_value.type == MONO_CONSTANT_SUMMARIZED_VALUE) {
1161                                 /* The easiest possible case: constant with constant */
1162                                 if ((index_value.value.constant.value >= 0) && (index_value.value.constant.value < array_value.value.constant.value)) {
1163                                         if (REPORT_ABC_REMOVAL) {
1164                                                 printf ("ARRAY-ACCESS: removed bounds check on array of constant length %d with constant index %d in method %s\n",
1165                                                                 array_value.value.constant.value, index_value.value.constant.value, mono_method_full_name (area->cfg->method, TRUE));
1166                                         }
1167                                         inst->flags |= (MONO_INST_NORANGECHECK);
1168                                 }
1169                         } else if (index_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1170                                 /* The index has a variable related value, which must be evaluated */
1171                                 int index_variable = index_value.value.variable.variable;
1172                                 MonoRelationsEvaluationContext *index_context = &(area->contexts [index_variable]);
1173
1174                                 clean_contexts (area->contexts, area->cfg->num_varinfo);
1175                                 evaluate_relation_with_target_variable (area, index_variable, index_variable, NULL);
1176                                 /* Apply index value kind */
1177                                 apply_value_kind_to_range (&(index_context->ranges.zero), index_value_kind);
1178
1179                                 if ((index_context->ranges.zero.lower >= 0) && (index_context->ranges.zero.upper < array_value.value.constant.value)) {
1180                                         if (REPORT_ABC_REMOVAL) {
1181                                                 printf ("ARRAY-ACCESS: removed bounds check on array of constant length %d with index %d ranging from %d to %d in method %s\n",
1182                                                                 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));
1183                                         }
1184                                         inst->flags |= (MONO_INST_NORANGECHECK);
1185                                 }
1186                         } else if (index_value_kind != MONO_UNKNOWN_INTEGER_VALUE) {
1187                                 /* The index has an unknown but bounded value */
1188                                 MonoRelationsEvaluationRange range;
1189                                 MONO_MAKE_RELATIONS_EVALUATION_RANGE_WEAK (range);
1190                                 apply_value_kind_to_range (&range, index_value_kind);
1191
1192                                 if ((range.lower >= 0) && (range.upper < array_value.value.constant.value)) {
1193                                         if (REPORT_ABC_REMOVAL) {
1194                                                 printf ("ARRAY-ACCESS: removed bounds check on array of constant length %d with unknown index ranging from %d to %d in method %s\n",
1195                                                                 array_value.value.constant.value, range.lower, range.upper, mono_method_full_name (area->cfg->method, TRUE));
1196                                         }
1197                                         inst->flags |= (MONO_INST_NORANGECHECK);
1198                                 }
1199                         }
1200                 }
1201         }
1202 }
1203
1204 /*
1205  * Recursively scan a tree of MonoInst looking for array accesses.
1206  * inst: the root of the MonoInst tree
1207  * area: the current evaluation area (it contains the relation graph and
1208  *       memory for all the evaluation contexts is already allocated)
1209  */
1210 static void
1211 process_inst (MonoInst *inst, MonoVariableRelationsEvaluationArea *area) {
1212         if (inst->opcode == CEE_LDELEMA) { /* Handle OP_LDELEMA2D, too */
1213                 if (TRACE_ABC_REMOVAL) {
1214                         printf ("Attempting check removal...\n");
1215                 }
1216
1217                 remove_abc_from_inst (inst, area);
1218         }
1219
1220         if (mono_burg_arity [inst->opcode]) {
1221                 process_inst (inst->inst_left, area);
1222                 if (mono_burg_arity [inst->opcode] > 1) {
1223                         process_inst (inst->inst_right, area);
1224                 }
1225         }
1226 }
1227
1228
1229
1230
1231 /*
1232  * Process a BB removing bounds checks from array accesses.
1233  * It does the following (in sequence):
1234  * - Get the BB entry condition
1235  * - Add its relations to the relation graph in the evaluation area
1236  * - Process all the MonoInst trees in the BB
1237  * - Recursively process all the children BBs in the dominator tree
1238  * - Remove the relations previously added to the relation graph
1239  *
1240  * bb: the BB that must be processed
1241  * area: the current evaluation area (it contains the relation graph and
1242  *       memory for all the evaluation contexts is already allocated)
1243  */
1244 static void
1245 process_block (MonoBasicBlock *bb, MonoVariableRelationsEvaluationArea *area) {
1246         int inst_index;
1247         MonoInst *current_inst;
1248         MonoAdditionalVariableRelationsForBB additional_relations;
1249         GSList *dominated_bb;
1250
1251         if (TRACE_ABC_REMOVAL) {
1252                 printf ("Processing block %d [dfn %d]...\n", bb->block_num, bb->dfn);
1253         }
1254
1255         get_relations_from_previous_bb (area, bb, &additional_relations);
1256         if (TRACE_ABC_REMOVAL) {
1257                 if (additional_relations.relation1.relation.relation != MONO_ANY_RELATION) {
1258                         printf ("Adding relation 1 on variable %d: ", additional_relations.relation1.variable);
1259                         print_summarized_value_relation (&(additional_relations.relation1.relation));
1260                         printf ("\n");
1261                 }
1262                 if (additional_relations.relation2.relation.relation != MONO_ANY_RELATION) {
1263                         printf ("Adding relation 2 on variable %d: ", additional_relations.relation2.variable);
1264                         print_summarized_value_relation (&(additional_relations.relation2.relation));
1265                         printf ("\n");
1266                 }
1267         }
1268         apply_change_to_evaluation_area (area, &(additional_relations.relation1));
1269         apply_change_to_evaluation_area (area, &(additional_relations.relation2));
1270
1271         inst_index = 0;
1272         MONO_BB_FOR_EACH_INS (bb, current_inst) {
1273                 if (TRACE_ABC_REMOVAL) {
1274                         printf ("Processing instruction %d\n", inst_index);
1275                         inst_index++;
1276                 }
1277
1278                 process_inst (current_inst, area);
1279         }
1280
1281
1282         if (TRACE_ABC_REMOVAL) {
1283                 printf ("Processing block %d [dfn %d] done.\n", bb->block_num, bb->dfn);
1284         }
1285
1286         for (dominated_bb = bb->dominated; dominated_bb != NULL; dominated_bb = dominated_bb->next) {
1287                 process_block ((MonoBasicBlock*) (dominated_bb->data), area);
1288         }
1289
1290         remove_change_from_evaluation_area (&(additional_relations.relation1));
1291         remove_change_from_evaluation_area (&(additional_relations.relation2));
1292 }
1293
1294
1295
1296 /**
1297  * mono_perform_abc_removal:
1298  * @cfg: Control Flow Graph
1299  *
1300  * Performs the ABC removal from a cfg in SSA form.
1301  * It does the following:
1302  * - Prepare the evaluation area
1303  * - Allocate memory for the relation graph in the evaluation area
1304  *   (of course, only for variable definitions) and summarize there all
1305  *   variable definitions
1306  * - Allocate memory for the evaluation contexts in the evaluation area
1307  * - Recursively process all the BBs in the dominator tree (it is enough
1308  *   to invoke the processing on the entry BB)
1309  *
1310  * cfg: the method code
1311  */
1312 void
1313 mono_perform_abc_removal (MonoCompile *cfg)
1314 {
1315         MonoVariableRelationsEvaluationArea area;
1316         int i;
1317
1318         verbose_level = cfg->verbose_level;
1319
1320         if (TRACE_ABC_REMOVAL) {
1321                 printf ("Removing array bound checks in %s\n", mono_method_full_name (cfg->method, TRUE));
1322         }
1323
1324         area.cfg = cfg;
1325         area.relations = (MonoSummarizedValueRelation *)
1326                 mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation) * (cfg->num_varinfo) * 2);
1327         area.contexts = (MonoRelationsEvaluationContext *)
1328                 mono_mempool_alloc (cfg->mempool, sizeof (MonoRelationsEvaluationContext) * (cfg->num_varinfo));
1329         area.variable_value_kind = (MonoIntegerValueKind *)
1330                 mono_mempool_alloc (cfg->mempool, sizeof (MonoIntegerValueKind) * (cfg->num_varinfo));
1331         for (i = 0; i < cfg->num_varinfo; i++) {
1332                 area.variable_value_kind [i] = MONO_UNKNOWN_INTEGER_VALUE;
1333                 area.relations [i].relation = MONO_EQ_RELATION;
1334                 area.relations [i].relation_is_static_definition = TRUE;
1335                 area.relations [i].next = NULL;
1336                 if (MONO_VARINFO (cfg, i)->def != NULL) {
1337                         MonoInst *value = get_variable_value_from_store_instruction (MONO_VARINFO (cfg, i)->def, i);
1338                         if (value != NULL) {
1339                                 gboolean is_array_type;
1340                                 MonoIntegerValueKind effective_value_kind;
1341                                 MonoRelationsEvaluationRange range;
1342                                 MonoSummarizedValueRelation *type_relation;
1343
1344                                 switch (cfg->varinfo [i]->inst_vtype->type) {
1345                                 case MONO_TYPE_ARRAY:
1346                                 case MONO_TYPE_SZARRAY:
1347                                         is_array_type = TRUE;
1348                                         goto handle_array_value;
1349                                 case MONO_TYPE_OBJECT:
1350                                         is_array_type = FALSE;
1351 handle_array_value:
1352                                         summarize_array_value (&area, value, &(area.relations [i].related_value), is_array_type);
1353                                         if (TRACE_ABC_REMOVAL) {
1354                                                 printf ("Summarized variable %d as array (is_array_type = %s): ", i, (is_array_type?"TRUE":"FALSE"));
1355                                                 print_summarized_value (&(area.relations [i].related_value));
1356                                                 printf ("\n");
1357                                         }
1358                                         break;
1359                                 case MONO_TYPE_I1:
1360                                         area.variable_value_kind [i] = MONO_INTEGER_VALUE_SIZE_1;
1361                                         goto handle_integer_value;
1362                                 case MONO_TYPE_U1:
1363                                         area.variable_value_kind [i] = MONO_UNSIGNED_INTEGER_VALUE_SIZE_1;
1364                                         goto handle_integer_value;
1365                                 case MONO_TYPE_I2:
1366                                         area.variable_value_kind [i] = MONO_INTEGER_VALUE_SIZE_2;
1367                                         goto handle_integer_value;
1368                                 case MONO_TYPE_U2:
1369                                         area.variable_value_kind [i] = MONO_UNSIGNED_INTEGER_VALUE_SIZE_2;
1370                                         goto handle_integer_value;
1371                                 case MONO_TYPE_I4:
1372                                         area.variable_value_kind [i] = MONO_INTEGER_VALUE_SIZE_4;
1373                                         goto handle_integer_value;
1374                                 case MONO_TYPE_U4:
1375                                         area.variable_value_kind [i] = MONO_UNSIGNED_INTEGER_VALUE_SIZE_4;
1376                                         goto handle_integer_value;
1377                                 case MONO_TYPE_I:
1378                                         area.variable_value_kind [i] = SIZEOF_VOID_P;
1379                                         goto handle_integer_value;
1380                                 case MONO_TYPE_U:
1381                                         area.variable_value_kind [i] = (MONO_UNSIGNED_VALUE_FLAG|SIZEOF_VOID_P);
1382                                         goto handle_integer_value;
1383                                 case MONO_TYPE_I8:
1384                                         area.variable_value_kind [i] = MONO_INTEGER_VALUE_SIZE_8;
1385                                         goto handle_integer_value;
1386                                 case MONO_TYPE_U8:
1387                                         area.variable_value_kind [i] = MONO_UNSIGNED_INTEGER_VALUE_SIZE_8;
1388 handle_integer_value:
1389                                         effective_value_kind = summarize_integer_value (&area, value, &(area.relations [i].related_value), area.variable_value_kind [i]);
1390                                         MONO_MAKE_RELATIONS_EVALUATION_RANGE_WEAK (range);
1391                                         apply_value_kind_to_range (&range, area.variable_value_kind [i]);
1392                                         apply_value_kind_to_range (&range, effective_value_kind);
1393
1394                                         if (range.upper < INT_MAX) {
1395                                                 type_relation = (MonoSummarizedValueRelation *) mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation));
1396                                                 type_relation->relation = MONO_LE_RELATION;
1397                                                 type_relation->related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1398                                                 type_relation->related_value.value.constant.value = range.upper;
1399                                                 type_relation->relation_is_static_definition = TRUE;
1400                                                 type_relation->next = area.relations [i].next;
1401                                                 area.relations [i].next = type_relation;
1402                                                 if (TRACE_ABC_REMOVAL) {
1403                                                         printf ("[var%d <= %d]", i, range.upper);
1404                                                 }
1405                                         }
1406                                         if (range.lower > INT_MIN) {
1407                                                 type_relation = (MonoSummarizedValueRelation *) mono_mempool_alloc (cfg->mempool, sizeof (MonoSummarizedValueRelation));
1408                                                 type_relation->relation = MONO_GE_RELATION;
1409                                                 type_relation->related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
1410                                                 type_relation->related_value.value.constant.value = range.lower;
1411                                                 type_relation->relation_is_static_definition = TRUE;
1412                                                 type_relation->next = area.relations [i].next;
1413                                                 area.relations [i].next = type_relation;
1414                                                 if (TRACE_ABC_REMOVAL) {
1415                                                         printf ("[var%d >= %d]", i, range.lower);
1416                                                 }
1417                                         }
1418                                         if (TRACE_ABC_REMOVAL) {
1419                                                 printf ("Summarized variable %d: ", i);
1420                                                 print_summarized_value (&(area.relations [i].related_value));
1421                                                 printf ("\n");
1422                                         }
1423                                         break;
1424                                 default:
1425                                         MAKE_VALUE_ANY (area.relations [i].related_value);
1426                                         if (TRACE_ABC_REMOVAL) {
1427                                                 printf ("Variable %d not handled (type %d)\n", i, cfg->varinfo [i]->inst_vtype->type);
1428                                         }
1429                                 }
1430                         } else {
1431                                 MAKE_VALUE_ANY (area.relations [i].related_value);
1432                                 if (TRACE_ABC_REMOVAL) {
1433                                         printf ("Definition of variable %d is not a proper store\n", i);
1434                                 }
1435                         }
1436                 } else {
1437                         MAKE_VALUE_ANY (area.relations [i].related_value);
1438                         if (TRACE_ABC_REMOVAL) {
1439                                 printf ("Variable %d has no definition, probably it is an argument\n", i);
1440                         }
1441                 }
1442         }
1443         for (i = 0; i < cfg->num_varinfo; i++) {
1444                 if (area.relations [i].related_value.type == MONO_VARIABLE_SUMMARIZED_VALUE) {
1445                         int related_index = cfg->num_varinfo + i;
1446                         int related_variable = area.relations [i].related_value.value.variable.variable;
1447
1448                         area.relations [related_index].relation = MONO_EQ_RELATION;
1449                         area.relations [related_index].relation_is_static_definition = TRUE;
1450                         area.relations [related_index].related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
1451                         area.relations [related_index].related_value.value.variable.variable = i;
1452                         area.relations [related_index].related_value.value.variable.delta = - area.relations [i].related_value.value.variable.delta;
1453
1454                         area.relations [related_index].next = area.relations [related_variable].next;
1455                         area.relations [related_variable].next = &(area.relations [related_index]);
1456
1457                         if (TRACE_ABC_REMOVAL) {
1458                                 printf ("Added symmetric summarized value for variable variable %d (to %d): ", i, related_variable);
1459                                 print_summarized_value (&(area.relations [related_index].related_value));
1460                                 printf ("\n");
1461                         }
1462                 }
1463         }
1464
1465         process_block (cfg->bblocks [0], &area);
1466 }
1467
1468 #endif /* DISABLE_SSA */
1469
1470 #endif /* DISABLE_JIT */