smatch_sval.c

   1 /*
   2  * smatch/smatch_sval.c
   3  *
   4  * Copyright (C) 2012 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  *
   9  * Basically the point of sval is that it can hold both ULLONG_MAX and
  10  * LLONG_MIN.  If it is an unsigned type then we use sval.uvalue or if it is
  11  * signed we use sval.value.
  12  *
  13  * I considered just using one bit to store whether the value was signed vs
  14  * unsigned but I think it might help to have the type information so we know
  15  * how to do type promotion.
  16  *
  17  */
  18
  19 #include "smatch.h"
  20 #include "smatch_slist.h"
  21 #include "smatch_extra.h"
  22
  23 __ALLOCATOR(sval_t, "svals", sval);
  24
  25 sval_t *sval_alloc(sval_t sval)
  26 {
  27         sval_t *ret;
  28
  29         ret = __alloc_sval(0);
  30         *ret = sval;
  31         return ret;
  32 }
  33
  34 sval_t *sval_alloc_permanent(sval_t sval)
  35 {
  36         sval_t *ret;
  37
  38         ret = malloc(sizeof(*ret));
  39         *ret = sval;
  40         return ret;
  41 }
  42
  43 sval_t sval_blank(struct expression *expr)
  44 {
  45         sval_t ret;
  46
  47         ret.type = get_type(expr);
  48         if (!ret.type)
  49                 ret.type = &llong_ctype;
  50         ret.value = 123456789;
  51
  52         return ret;
  53 }
  54
  55 sval_t sval_type_val(struct symbol *type, long long val)
  56 {
  57         sval_t ret;
  58
  59         ret.type = type;
  60         ret.value = val;
  61         return ret;
  62 }
  63
  64 sval_t sval_from_val(struct expression *expr, long long val)
  65 {
  66         sval_t ret;
  67
  68         ret = sval_blank(expr);
  69         ret.value = val;
  70         ret = sval_cast(get_type(expr), ret);
  71
  72         return ret;
  73 }
  74
  75 int sval_unsigned(sval_t sval)
  76 {
  77         return type_unsigned(sval.type);
  78 }
  79
  80 int sval_signed(sval_t sval)
  81 {
  82         return !type_unsigned(sval.type);
  83 }
  84
  85 int sval_bits(sval_t sval)
  86 {
  87         return type_bits(sval.type);
  88 }
  89
  90 int sval_positive_bits(sval_t sval)
  91 {
  92         return type_positive_bits(sval.type);
  93 }
  94
  95 int sval_bits_used(sval_t sval)
  96 {
  97         int i;
  98
  99         for (i = 64; i >= 1; i--) {
 100                 if (sval.uvalue & (1ULL << (i - 1)))
 101                         return i;
 102         }
 103         return 0;
 104 }
 105
 106 int sval_is_negative(sval_t sval)
 107 {
 108         if (type_unsigned(sval.type))
 109                 return 0;
 110         if (sval.value < 0)
 111                 return 1;
 112         return 0;
 113 }
 114
 115 int sval_is_positive(sval_t sval)
 116 {
 117         return !sval_is_negative(sval);
 118 }
 119
 120 int sval_is_min(sval_t sval)
 121 {
 122         sval_t min = sval_type_min(sval.type);
 123
 124         if (sval_unsigned(sval)) {
 125                 if (sval.uvalue == 0)
 126                         return 1;
 127                 return 0;
 128         }
 129         /* return true for less than min as well */
 130         return (sval.value <= min.value);
 131 }
 132
 133 int sval_is_max(sval_t sval)
 134 {
 135         sval_t max = sval_type_max(sval.type);
 136
 137         if (sval_unsigned(sval))
 138                 return (sval.uvalue >= max.value);
 139         return (sval.value >= max.value);
 140 }
 141
 142 int sval_is_a_min(sval_t sval)
 143 {
 144         if (sval_signed(sval) && sval.value == SHRT_MIN)
 145                 return 1;
 146         if (sval_signed(sval) && sval.value == INT_MIN)
 147                 return 1;
 148         if (sval_signed(sval) && sval.value == LLONG_MIN)
 149                 return 1;
 150         return 0;
 151 }
 152
 153 int sval_is_a_max(sval_t sval)
 154 {
 155         if (sval.uvalue == SHRT_MAX)
 156                 return 1;
 157         if (sval.uvalue == INT_MAX)
 158                 return 1;
 159         if (sval.uvalue == LLONG_MAX)
 160                 return 1;
 161         if (sval.uvalue == USHRT_MAX)
 162                 return 1;
 163         if (sval.uvalue == UINT_MAX)
 164                 return 1;
 165         if (sval_unsigned(sval) && sval.uvalue == ULLONG_MAX)
 166                 return 1;
 167         return 0;
 168 }
 169
 170 int sval_is_negative_min(sval_t sval)
 171 {
 172         if (!sval_is_negative(sval))
 173                 return 0;
 174         return sval_is_min(sval);
 175 }
 176
 177 /*
 178  * Returns -1 if one is smaller, 0 if they are the same and 1 if two is larger.
 179  */
 180 int sval_cmp(sval_t one, sval_t two)
 181 {
 182         struct symbol *type;
 183
 184         type = one.type;
 185         if (sval_positive_bits(two) > sval_positive_bits(one))
 186                 type = two.type;
 187         if (type_bits(type) < 31)
 188                 type = &int_ctype;
 189
 190         one = sval_cast(type, one);
 191         two = sval_cast(type, two);
 192
 193         if (type_unsigned(type)) {
 194                 if (one.uvalue < two.uvalue)
 195                         return -1;
 196                 if (one.uvalue == two.uvalue)
 197                         return 0;
 198                 return 1;
 199         }
 200         /* fix me handle type promotion and unsigned values */
 201         if (one.value < two.value)
 202                 return -1;
 203         if (one.value == two.value)
 204                 return 0;
 205         return 1;
 206 }
 207
 208 int sval_cmp_t(struct symbol *type, sval_t one, sval_t two)
 209 {
 210         sval_t one_cast, two_cast;
 211
 212         one_cast = sval_cast(type, one);
 213         two_cast = sval_cast(type, two);
 214         return sval_cmp(one_cast, two_cast);
 215 }
 216
 217 int sval_cmp_val(sval_t one, long long val)
 218 {
 219         sval_t sval;
 220
 221         sval = sval_type_val(&llong_ctype, val);
 222         return sval_cmp(one, sval);
 223 }
 224
 225 sval_t sval_min(sval_t one, sval_t two)
 226 {
 227         if (sval_cmp(one, two) > 0)
 228                 return two;
 229         return one;
 230 }
 231
 232 sval_t sval_max(sval_t one, sval_t two)
 233 {
 234         if (sval_cmp(one, two) < 0)
 235                 return two;
 236         return one;
 237 }
 238
 239 int sval_too_low(struct symbol *type, sval_t sval)
 240 {
 241         if (sval_is_negative(sval) && type_unsigned(type))
 242                 return 1;
 243         if (type_signed(type) &&  sval_unsigned(sval))
 244                 return 0;
 245         if (sval_cmp(sval, sval_type_min(type)) < 0)
 246                 return 1;
 247         return 0;
 248 }
 249
 250 int sval_too_high(struct symbol *type, sval_t sval)
 251 {
 252         if (sval_is_negative(sval))
 253                 return 0;
 254         if (sval.uvalue > sval_type_max(type).uvalue)
 255                 return 1;
 256         return 0;
 257 }
 258
 259 int sval_fits(struct symbol *type, sval_t sval)
 260 {
 261         if (sval_too_low(type, sval))
 262                 return 0;
 263         if (sval_too_high(type, sval))
 264                 return 0;
 265         return 1;
 266 }
 267
 268 sval_t sval_cast(struct symbol *type, sval_t sval)
 269 {
 270         sval_t ret;
 271
 272         if (!type)
 273                 type = &llong_ctype;
 274
 275         ret.type = type;
 276         switch (sval_bits(ret)) {
 277         case 8:
 278                 if (sval_unsigned(ret))
 279                         ret.value = (long long)(unsigned char)sval.value;
 280                 else
 281                         ret.value = (long long)(char)sval.value;
 282                 break;
 283         case 16:
 284                 if (sval_unsigned(ret))
 285                         ret.value = (long long)(unsigned short)sval.value;
 286                 else
 287                         ret.value = (long long)(short)sval.value;
 288                 break;
 289         case 32:
 290                 if (sval_unsigned(ret))
 291                         ret.value = (long long)(unsigned int)sval.value;
 292                 else
 293                         ret.value = (long long)(int)sval.value;
 294                 break;
 295         default:
 296                 ret.value = sval.value;
 297         }
 298         return ret;
 299
 300 }
 301
 302 sval_t sval_preop(sval_t sval, int op)
 303 {
 304         switch (op) {
 305         case '!':
 306                 sval.value = !sval.value;
 307                 break;
 308         case '~':
 309                 sval.value = ~sval.value;
 310                 /* fixme: should probably cast this here */
 311                 break;
 312         case '-':
 313                 sval.value = -sval.value;
 314                 break;
 315         }
 316         return sval;
 317 }
 318
 319 static sval_t sval_binop_unsigned(struct symbol *type, sval_t left, int op, sval_t right)
 320 {
 321         sval_t ret;
 322
 323         ret.type = type;
 324         switch (op) {
 325         case '*':
 326                 ret.uvalue =  left.uvalue * right.uvalue;
 327                 break;
 328         case '/':
 329                 if (right.uvalue == 0) {
 330                         sm_msg("debug: %s: divide by zero", __func__);
 331                         ret.uvalue = 123456789;
 332                 } else {
 333                         ret.uvalue = left.uvalue / right.uvalue;
 334                 }
 335                 break;
 336         case '+':
 337                 ret.uvalue = left.uvalue + right.uvalue;
 338                 break;
 339         case '-':
 340                 ret.uvalue = left.uvalue - right.uvalue;
 341                 break;
 342         case '%':
 343                 if (right.uvalue == 0) {
 344                         sm_msg("internal error: %s: MOD by zero", __func__);
 345                         ret.uvalue = 123456789;
 346                 } else {
 347                         ret.uvalue = left.uvalue % right.uvalue;
 348                 }
 349                 break;
 350         case '|':
 351                 ret.uvalue = left.uvalue | right.uvalue;
 352                 break;
 353         case '&':
 354                 ret.uvalue = left.uvalue & right.uvalue;
 355                 break;
 356         case SPECIAL_RIGHTSHIFT:
 357                 ret.uvalue = left.uvalue >> right.uvalue;
 358                 break;
 359         case SPECIAL_LEFTSHIFT:
 360                 ret.uvalue = left.uvalue << right.uvalue;
 361                 break;
 362         case '^':
 363                 ret.uvalue = left.uvalue ^ right.uvalue;
 364                 break;
 365         default:
 366                 sm_msg("internal error: %s: unhandled binop %s", __func__,
 367                        show_special(op));
 368                 ret.uvalue = 1234567;
 369         }
 370         return ret;
 371 }
 372
 373
 374 static sval_t sval_binop_signed(struct symbol *type, sval_t left, int op, sval_t right)
 375 {
 376         sval_t ret;
 377
 378         ret.type = type;
 379         switch (op) {
 380         case '*':
 381                 ret.value =  left.value * right.value;
 382                 break;
 383         case '/':
 384                 if (right.value == 0) {
 385                         sm_msg("debug: %s: divide by zero", __func__);
 386                         ret.value = 123456789;
 387                 } else if (left.value == LLONG_MIN && right.value == -1) {
 388                         sm_msg("debug: %s: invalid divide LLONG_MIN/-1", __func__);
 389                         ret.value = 12345678;
 390                 } else {
 391                         ret.value = left.value / right.value;
 392                 }
 393                 break;
 394         case '+':
 395                 ret.value = left.value + right.value;
 396                 break;
 397         case '-':
 398                 ret.value = left.value - right.value;
 399                 break;
 400         case '%':
 401                 if (right.value == 0) {
 402                         sm_msg("internal error: %s: MOD by zero", __func__);
 403                         ret.value = 123456789;
 404                 } else {
 405                         ret.value = left.value % right.value;
 406                 }
 407                 break;
 408         case '|':
 409                 ret.value = left.value | right.value;
 410                 break;
 411         case '&':
 412                 ret.value = left.value & right.value;
 413                 break;
 414         case SPECIAL_RIGHTSHIFT:
 415                 ret.value = left.value >> right.value;
 416                 break;
 417         case SPECIAL_LEFTSHIFT:
 418                 ret.value = left.value << right.value;
 419                 break;
 420         case '^':
 421                 ret.value = left.value ^ right.value;
 422                 break;
 423         default:
 424                 sm_msg("internal error: %s: unhandled binop %s", __func__,
 425                        show_special(op));
 426                 ret.value = 1234567;
 427         }
 428         return ret;
 429 }
 430
 431 sval_t sval_binop(sval_t left, int op, sval_t right)
 432 {
 433         struct symbol *type;
 434         sval_t ret;
 435
 436         type = left.type;
 437         if (sval_positive_bits(right) > sval_positive_bits(left))
 438                 type = right.type;
 439         if (type_positive_bits(type) < 31)
 440                 type = &int_ctype;
 441
 442         if (type_unsigned(type))
 443                 ret = sval_binop_unsigned(type, left, op, right);
 444         else
 445                 ret = sval_binop_signed(type, left, op, right);
 446         return ret;
 447 }
 448
 449 int sval_binop_overflows(sval_t left, int op, sval_t right)
 450 {
 451         struct symbol *type;
 452         sval_t max, min;
 453
 454         type = left.type;
 455         if (type_positive_bits(right.type) > type_positive_bits(left.type))
 456                 type = right.type;
 457         if (type_positive_bits(type) < 31)
 458                 return 0;
 459         max = sval_type_max(type);
 460         min = sval_type_min(type);
 461
 462         switch (op) {
 463         case '+':
 464                 if (left.uvalue > max.uvalue - right.uvalue)
 465                         return 1;
 466                 return 0;
 467         case '*':
 468                 return right.uvalue != 0 && left.uvalue > max.uvalue / right.uvalue;
 469         case '-':
 470                 return sval_cmp(right, sval_binop(min, '+', left)) < 0;
 471         }
 472         return 0;
 473 }
 474
 475 const char *sval_to_str(sval_t sval)
 476 {
 477         char buf[30];
 478
 479         if (sval_unsigned(sval) && sval.value == ULLONG_MAX)
 480                 return "u64max";
 481         if (sval_unsigned(sval) && sval.value == UINT_MAX)
 482                 return "u32max";
 483         if (sval_unsigned(sval) && sval.value == USHRT_MAX)
 484                 return "u16max";
 485
 486         if (sval_signed(sval) && sval.value == LLONG_MAX)
 487                 return "s64max";
 488         if (sval_signed(sval) && sval.value == INT_MAX)
 489                 return "s32max";
 490         if (sval_signed(sval) && sval.value == SHRT_MAX)
 491                 return "s16max";
 492
 493         if (sval_signed(sval) && sval.value == SHRT_MIN)
 494                 return "s16min";
 495         if (sval_signed(sval) && sval.value == INT_MIN)
 496                 return "s32min";
 497         if (sval_signed(sval) && sval.value == LLONG_MIN)
 498                 return "s64min";
 499
 500         if (sval_unsigned(sval))
 501                 snprintf(buf, sizeof(buf), "%llu", sval.value);
 502         else if (sval.value < 0)
 503                 snprintf(buf, sizeof(buf), "(%lld)", sval.value);
 504         else
 505                 snprintf(buf, sizeof(buf), "%lld", sval.value);
 506
 507         return alloc_sname(buf);
 508 }
 509
 510 const char *sval_to_numstr(sval_t sval)
 511 {
 512         char buf[30];
 513
 514         if (sval_unsigned(sval))
 515                 snprintf(buf, sizeof(buf), "%llu", sval.value);
 516         else if (sval.value < 0)
 517                 snprintf(buf, sizeof(buf), "(%lld)", sval.value);
 518         else
 519                 snprintf(buf, sizeof(buf), "%lld", sval.value);
 520
 521         return alloc_sname(buf);
 522 }
 523
 524 sval_t ll_to_sval(long long val)
 525 {
 526         sval_t ret;
 527
 528         ret.type = &llong_ctype;
 529         ret.value = val;
 530         return ret;
 531 }
 532
 533 static void free_svals(struct symbol *sym)
 534 {
 535         if (__inline_fn)
 536                 return;
 537         clear_sval_alloc();
 538 }
 539
 540 void register_sval(int my_id)
 541 {
 542         add_hook(&free_svals, END_FUNC_HOOK);
 543 }