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 (sval_cmp_val(sval, 0) < 0)
 109                 return 1;
 110         return 0;
 111 }
 112
 113 int sval_is_positive(sval_t sval)
 114 {
 115         return !sval_is_negative(sval);
 116 }
 117
 118 int sval_is_min(sval_t sval)
 119 {
 120         sval_t min = sval_type_min(sval.type);
 121
 122         if (sval_unsigned(sval)) {
 123                 if (sval.uvalue == 0)
 124                         return 1;
 125                 return 0;
 126         }
 127         /* return true for less than min as well */
 128         return (sval.value <= min.value);
 129 }
 130
 131 int sval_is_max(sval_t sval)
 132 {
 133         sval_t max = sval_type_max(sval.type);
 134
 135         if (sval_unsigned(sval))
 136                 return (sval.uvalue >= max.value);
 137         return (sval.value >= max.value);
 138 }
 139
 140 int sval_is_a_min(sval_t sval)
 141 {
 142         if (sval_signed(sval) && sval.value == SHRT_MIN)
 143                 return 1;
 144         if (sval_signed(sval) && sval.value == INT_MIN)
 145                 return 1;
 146         if (sval_signed(sval) && sval.value == LLONG_MIN)
 147                 return 1;
 148         return 0;
 149 }
 150
 151 int sval_is_a_max(sval_t sval)
 152 {
 153         if (sval.uvalue == SHRT_MAX)
 154                 return 1;
 155         if (sval.uvalue == INT_MAX)
 156                 return 1;
 157         if (sval.uvalue == LLONG_MAX)
 158                 return 1;
 159         if (sval.uvalue == USHRT_MAX)
 160                 return 1;
 161         if (sval.uvalue == UINT_MAX)
 162                 return 1;
 163         if (sval_unsigned(sval) && sval.uvalue == ULLONG_MAX)
 164                 return 1;
 165         return 0;
 166 }
 167
 168 /*
 169  * Returns -1 if one is smaller, 0 if they are the same and 1 if two is larger.
 170  */
 171 int sval_cmp(sval_t one, sval_t two)
 172 {
 173         struct symbol *type;
 174
 175         type = one.type;
 176         if (sval_positive_bits(two) > sval_positive_bits(one))
 177                 type = two.type;
 178         if (type_bits(type) < 31)
 179                 type = &int_ctype;
 180
 181         one = sval_cast(type, one);
 182         two = sval_cast(type, two);
 183
 184         if (type_unsigned(type)) {
 185                 if (one.uvalue < two.uvalue)
 186                         return -1;
 187                 if (one.uvalue == two.uvalue)
 188                         return 0;
 189                 return 1;
 190         }
 191         /* fix me handle type promotion and unsigned values */
 192         if (one.value < two.value)
 193                 return -1;
 194         if (one.value == two.value)
 195                 return 0;
 196         return 1;
 197 }
 198
 199 int sval_cmp_t(struct symbol *type, sval_t one, sval_t two)
 200 {
 201         sval_t one_cast, two_cast;
 202
 203         one_cast = sval_cast(type, one);
 204         two_cast = sval_cast(type, two);
 205         return sval_cmp(one_cast, two_cast);
 206 }
 207
 208 int sval_cmp_val(sval_t one, long long val)
 209 {
 210         sval_t sval;
 211
 212         sval = sval_type_val(&llong_ctype, val);
 213         return sval_cmp(one, sval);
 214 }
 215
 216 int sval_too_low(struct symbol *type, sval_t sval)
 217 {
 218         if (sval_is_negative(sval) && type_unsigned(type))
 219                 return 1;
 220         if (type_signed(type) &&  sval_unsigned(sval))
 221                 return 0;
 222         if (sval_cmp(sval, sval_type_min(type)) < 0)
 223                 return 1;
 224         return 0;
 225 }
 226
 227 int sval_too_high(struct symbol *type, sval_t sval)
 228 {
 229         if (sval_is_negative(sval))
 230                 return 0;
 231         if (sval_cmp(sval, sval_type_max(type)) > 0)
 232                 return 1;
 233         return 0;
 234 }
 235
 236 int sval_fits(struct symbol *type, sval_t sval)
 237 {
 238         if (sval_too_low(type, sval))
 239                 return 0;
 240         if (sval_too_high(type, sval))
 241                 return 0;
 242         return 1;
 243 }
 244
 245 sval_t sval_cast(struct symbol *type, sval_t sval)
 246 {
 247         sval_t ret;
 248
 249         if (!type)
 250                 type = &llong_ctype;
 251
 252         ret.type = type;
 253         switch (sval_bits(ret)) {
 254         case 8:
 255                 if (sval_unsigned(ret))
 256                         ret.value = (long long)(unsigned char)sval.value;
 257                 else
 258                         ret.value = (long long)(char)sval.value;
 259                 break;
 260         case 16:
 261                 if (sval_unsigned(ret))
 262                         ret.value = (long long)(unsigned short)sval.value;
 263                 else
 264                         ret.value = (long long)(short)sval.value;
 265                 break;
 266         case 32:
 267                 if (sval_unsigned(ret))
 268                         ret.value = (long long)(unsigned int)sval.value;
 269                 else
 270                         ret.value = (long long)(int)sval.value;
 271                 break;
 272         default:
 273                 ret.value = sval.value;
 274         }
 275         return ret;
 276
 277 }
 278
 279 sval_t sval_preop(sval_t sval, int op)
 280 {
 281         switch (op) {
 282         case '!':
 283                 sval.value = !sval.value;
 284                 break;
 285         case '~':
 286                 sval.value = ~sval.value;
 287                 /* fixme: should probably cast this here */
 288                 break;
 289         case '-':
 290                 sval.value = -sval.value;
 291                 break;
 292         }
 293         return sval;
 294 }
 295
 296 static sval_t sval_binop_unsigned(struct symbol *type, sval_t left, int op, sval_t right)
 297 {
 298         sval_t ret;
 299
 300         ret.type = type;
 301         switch (op) {
 302         case '*':
 303                 ret.uvalue =  left.uvalue * right.uvalue;
 304                 break;
 305         case '/':
 306                 if (right.uvalue == 0) {
 307                         sm_msg("debug: %s: divide by zero", __func__);
 308                         ret.uvalue = 123456789;
 309                 } else {
 310                         ret.uvalue = left.uvalue / right.uvalue;
 311                 }
 312                 break;
 313         case '+':
 314                 ret.uvalue = left.uvalue + right.uvalue;
 315                 break;
 316         case '-':
 317                 ret.uvalue = left.uvalue - right.uvalue;
 318                 break;
 319         case '%':
 320                 if (right.uvalue == 0) {
 321                         sm_msg("internal error: %s: MOD by zero", __func__);
 322                         ret.uvalue = 123456789;
 323                 } else {
 324                         ret.uvalue = left.uvalue % right.uvalue;
 325                 }
 326                 break;
 327         case '|':
 328                 ret.uvalue = left.uvalue | right.uvalue;
 329                 break;
 330         case '&':
 331                 ret.uvalue = left.uvalue & right.uvalue;
 332                 break;
 333         case SPECIAL_RIGHTSHIFT:
 334                 ret.uvalue = left.uvalue >> right.uvalue;
 335                 break;
 336         case SPECIAL_LEFTSHIFT:
 337                 ret.uvalue = left.uvalue << right.uvalue;
 338                 break;
 339         case '^':
 340                 ret.uvalue = left.uvalue ^ right.uvalue;
 341                 break;
 342         default:
 343                 sm_msg("internal error: %s: unhandled binop %s", __func__,
 344                        show_special(op));
 345                 ret.uvalue = 1234567;
 346         }
 347         return ret;
 348 }
 349
 350
 351 static sval_t sval_binop_signed(struct symbol *type, sval_t left, int op, sval_t right)
 352 {
 353         sval_t ret;
 354
 355         ret.type = type;
 356         switch (op) {
 357         case '*':
 358                 ret.value =  left.value * right.value;
 359                 break;
 360         case '/':
 361                 if (right.value == 0) {
 362                         sm_msg("debug: %s: divide by zero", __func__);
 363                         ret.value = 123456789;
 364                 } else if (left.value == LLONG_MIN && right.value == -1) {
 365                         sm_msg("debug: %s: invalid divide LLONG_MIN/-1", __func__);
 366                         ret.value = 12345678;
 367                 } else {
 368                         ret.value = left.value / right.value;
 369                 }
 370                 break;
 371         case '+':
 372                 ret.value = left.value + right.value;
 373                 break;
 374         case '-':
 375                 ret.value = left.value - right.value;
 376                 break;
 377         case '%':
 378                 if (right.value == 0) {
 379                         sm_msg("internal error: %s: MOD by zero", __func__);
 380                         ret.value = 123456789;
 381                 } else {
 382                         ret.value = left.value % right.value;
 383                 }
 384                 break;
 385         case '|':
 386                 ret.value = left.value | right.value;
 387                 break;
 388         case '&':
 389                 ret.value = left.value & right.value;
 390                 break;
 391         case SPECIAL_RIGHTSHIFT:
 392                 ret.value = left.value >> right.value;
 393                 break;
 394         case SPECIAL_LEFTSHIFT:
 395                 ret.value = left.value << right.value;
 396                 break;
 397         case '^':
 398                 ret.value = left.value ^ right.value;
 399                 break;
 400         default:
 401                 sm_msg("internal error: %s: unhandled binop %s", __func__,
 402                        show_special(op));
 403                 ret.value = 1234567;
 404         }
 405         return ret;
 406 }
 407
 408 sval_t sval_binop(sval_t left, int op, sval_t right)
 409 {
 410         struct symbol *type;
 411         sval_t ret;
 412
 413         type = left.type;
 414         if (sval_positive_bits(right) > sval_positive_bits(left))
 415                 type = right.type;
 416         if (type_positive_bits(type) < 31)
 417                 type = &int_ctype;
 418
 419         if (type_unsigned(type))
 420                 ret = sval_binop_unsigned(type, left, op, right);
 421         else
 422                 ret = sval_binop_signed(type, left, op, right);
 423         return ret;
 424 }
 425
 426 int sval_binop_overflows(sval_t left, int op, sval_t right)
 427 {
 428         sval_t max = sval_type_max(left.type);
 429
 430         switch (op) {
 431         case '+':
 432                 if (sval_cmp(left, sval_binop(max, '-', right)) > 0)
 433                         return 1;
 434                 return 0;
 435         case '*':
 436                 if (sval_cmp(left, sval_binop(max, '/', right)) > 0)
 437                         return 1;
 438                 return 0;
 439         }
 440         return 0;
 441 }
 442
 443 const char *sval_to_str(sval_t sval)
 444 {
 445         char buf[30];
 446
 447         if (sval_unsigned(sval) && sval.value == ULLONG_MAX)
 448                 return "u64max";
 449         if (sval.value == LLONG_MAX)
 450                 return "s64max";
 451         if (sval_unsigned(sval) && sval.value == UINT_MAX)
 452                 return "u32max";
 453         if (sval.value == INT_MAX)
 454                 return "s32max";
 455         if (sval_unsigned(sval) && sval.value == USHRT_MAX)
 456                 return "u16max";
 457         if (sval.value == SHRT_MAX)
 458                 return "s16max";
 459
 460         if (sval_signed(sval) && sval.value == SHRT_MIN)
 461                 return "s16min";
 462         if (sval_signed(sval) && sval.value == INT_MIN)
 463                 return "s32min";
 464         if (sval_signed(sval) && sval.value == LLONG_MIN)
 465                 return "s64min";
 466
 467         if (sval_unsigned(sval))
 468                 snprintf(buf, sizeof(buf), "%llu", sval.value);
 469         else if (sval.value < 0)
 470                 snprintf(buf, sizeof(buf), "(%lld)", sval.value);
 471         else
 472                 snprintf(buf, sizeof(buf), "%lld", sval.value);
 473
 474         return alloc_sname(buf);
 475 }
 476
 477 const char *sval_to_numstr(sval_t sval)
 478 {
 479         char buf[30];
 480
 481         if (sval_unsigned(sval))
 482                 snprintf(buf, sizeof(buf), "%llu", sval.value);
 483         else if (sval.value < 0)
 484                 snprintf(buf, sizeof(buf), "(%lld)", sval.value);
 485         else
 486                 snprintf(buf, sizeof(buf), "%lld", sval.value);
 487
 488         return alloc_sname(buf);
 489 }
 490
 491 sval_t ll_to_sval(long long val)
 492 {
 493         sval_t ret;
 494
 495         ret.type = &llong_ctype;
 496         ret.value = val;
 497         return ret;
 498 }
 499
 500 static void free_svals(struct symbol *sym)
 501 {
 502         clear_sval_alloc();
 503 }
 504
 505 void register_sval(int my_id)
 506 {
 507         add_hook(&free_svals, END_FUNC_HOOK);
 508 }