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GeezerVison is showing github.com — cpython/Python/flowgraph.c at main · python/cpython Expand file tree/ Copy pathflowgraph.cMore file actions 4284 lines (3936 loc) · 137 KB / Copy pathflowgraph.cFile metadata and controls4284 lines (3936 loc) · 137 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 #include "Python.h" #include "opcode.h" #include "pycore_c_array.h" // _Py_CArray_EnsureCapacity #include "pycore_flowgraph.h" #include "pycore_compile.h" #include "pycore_intrinsics.h" #include "pycore_pymem.h" // _PyMem_IsPtrFreed() #include "pycore_long.h" // _PY_IS_SMALL_INT() #include "pycore_hashtable.h" // _Py_hashtable_t #include "pycore_opcode_utils.h" #include "pycore_opcode_metadata.h" // OPCODE_HAS_ARG, etc #include "pycore_pystate.h" // _PyInterpreterState_GET() #include "pycore_stackref.h" // PyStackRef_AsPyObjectBorrow() #include <stdbool.h> #undef SUCCESS #undef ERROR #define SUCCESS 0 #define ERROR -1 #define RETURN_IF_ERROR(X) \ if ((X) == -1) { \ return ERROR; \ } #define DEFAULT_BLOCK_SIZE 16 typedef _Py_SourceLocation location; typedef _PyJumpTargetLabel jump_target_label; typedef struct _PyCfgInstruction { int i_opcode; int i_oparg; _Py_SourceLocation i_loc; struct _PyCfgBasicblock *i_target; /* target block (if jump instruction) */ struct _PyCfgBasicblock *i_except; /* target block when exception is raised */ } cfg_instr; typedef struct _PyCfgBasicblock { /* Each basicblock in a compilation unit is linked via b_list in the reverse order that blocks are allocated. b_list points to the previously allocated block, not to be confused with b_next, which is next by control flow. */ struct _PyCfgBasicblock *b_list; /* The label of this block if it is a jump target, -1 otherwise */ _PyJumpTargetLabel b_label; /* Basic block is an exception handler that preserves lasti */ unsigned b_preserve_lasti : 1; /* Used by compiler passes to mark whether they have visited a basic block. */ unsigned b_visited : 1; /* b_except_handler is used by the cold-detection algorithm to mark exception targets */ unsigned b_except_handler : 1; /* b_cold is true if this block is not perf critical (like an exception handler) */ unsigned b_cold : 1; /* b_warm is used by the cold-detection algorithm to mark blocks which are definitely not cold */ unsigned b_warm : 1; /* Exception stack at start of block, used by assembler to create the exception handling table */ struct _PyCfgExceptStack *b_exceptstack; /* pointer to an array of instructions, initially NULL */ cfg_instr *b_instr; /* If b_next is non-NULL, it is a pointer to the next block reached by normal control flow. */ struct _PyCfgBasicblock *b_next; /* number of instructions used */ int b_iused; /* length of instruction array (b_instr) */ int b_ialloc; /* Used by add_checks_for_loads_of_unknown_variables */ uint64_t b_unsafe_locals_mask; /* Number of predecessors that a block has. */ int b_predecessors; /* depth of stack upon entry of block, computed by stackdepth() */ int b_startdepth; } basicblock; struct _PyCfgBuilder { /* The entryblock, at which control flow begins. All blocks of the CFG are reachable through the b_next links */ struct _PyCfgBasicblock *g_entryblock; /* Pointer to the most recently allocated block. By following b_list links, you can reach all allocated blocks. */ struct _PyCfgBasicblock *g_block_list; /* pointer to the block currently being constructed */ struct _PyCfgBasicblock *g_curblock; /* label for the next instruction to be placed */ _PyJumpTargetLabel g_current_label; }; typedef struct _PyCfgBuilder cfg_builder; #define SAME_LABEL(L1, L2) ((L1).id == (L2).id) #define IS_LABEL(L) (!SAME_LABEL((L), (NO_LABEL))) #define LOCATION(LNO, END_LNO, COL, END_COL) \ ((const _Py_SourceLocation){(LNO), (END_LNO), (COL), (END_COL)}) static inline int is_block_push(cfg_instr *i) { assert(OPCODE_HAS_ARG(i->i_opcode) || !IS_BLOCK_PUSH_OPCODE(i->i_opcode)); return IS_BLOCK_PUSH_OPCODE(i->i_opcode); } static inline int is_jump(cfg_instr *i) { return OPCODE_HAS_JUMP(i->i_opcode); } /* One arg*/ #define INSTR_SET_OP1(I, OP, ARG) \ do { \ assert(OPCODE_HAS_ARG(OP)); \ cfg_instr *_instr__ptr_ = (I); \ _instr__ptr_->i_opcode = (OP); \ _instr__ptr_->i_oparg = (ARG); \ } while (0); /* No args*/ #define INSTR_SET_OP0(I, OP) \ do { \ assert(!OPCODE_HAS_ARG(OP)); \ cfg_instr *_instr__ptr_ = (I); \ _instr__ptr_->i_opcode = (OP); \ _instr__ptr_->i_oparg = 0; \ } while (0); #define INSTR_SET_LOC(I, LOC) \ do { \ cfg_instr *_instr__ptr_ = (I); \ _instr__ptr_->i_loc = (LOC); \ } while (0); /***** Blocks *****/ /* Returns the offset of the next instruction in the current block's b_instr array. Resizes the b_instr as necessary. Returns -1 on failure. */ static int basicblock_next_instr(basicblock *b) { assert(b != NULL); _Py_c_array_t array = { .array = (void*)b->b_instr, .allocated_entries = b->b_ialloc, .item_size = sizeof(cfg_instr), .initial_num_entries = DEFAULT_BLOCK_SIZE, }; RETURN_IF_ERROR(_Py_CArray_EnsureCapacity(&array, b->b_iused + 1)); b->b_instr = array.array; b->b_ialloc = array.allocated_entries; return b->b_iused++; } static cfg_instr * basicblock_last_instr(const basicblock *b) { assert(b->b_iused >= 0); if (b->b_iused > 0) { assert(b->b_instr != NULL); return &b->b_instr[b->b_iused - 1]; } return NULL; } /* Allocate a new block and return a pointer to it. Returns NULL on error. */ static basicblock * cfg_builder_new_block(cfg_builder *g) { basicblock *b = (basicblock *)PyMem_Calloc(1, sizeof(basicblock)); if (b == NULL) { PyErr_NoMemory(); return NULL; } /* Extend the singly linked list of blocks with new block. */ b->b_list = g->g_block_list; g->g_block_list = b; b->b_label = NO_LABEL; return b; } static int basicblock_addop(basicblock *b, int opcode, int oparg, location loc, basicblock *except) { assert(IS_WITHIN_OPCODE_RANGE(opcode)); assert(!IS_ASSEMBLER_OPCODE(opcode)); assert(OPCODE_HAS_ARG(opcode) || HAS_TARGET(opcode) || oparg == 0); assert(0 <= oparg && oparg < (1 << 30)); int off = basicblock_next_instr(b); if (off < 0) { return ERROR; } cfg_instr *i = &b->b_instr[off]; i->i_opcode = opcode; i->i_oparg = oparg; i->i_loc = loc; i->i_except = except; // memory is already zero initialized assert(i->i_target == NULL); return SUCCESS; } static int basicblock_add_jump(basicblock *b, int opcode, basicblock *target, location loc, basicblock *except) { cfg_instr *last = basicblock_last_instr(b); if (last && is_jump(last)) { return ERROR; } RETURN_IF_ERROR( basicblock_addop(b, opcode, target->b_label.id, loc, except)); last = basicblock_last_instr(b); assert(last && last->i_opcode == opcode); last->i_target = target; return SUCCESS; } static inline int basicblock_append_instructions(basicblock *to, basicblock *from) { for (int i = 0; i < from->b_iused; i++) { int n = basicblock_next_instr(to); if (n < 0) { return ERROR; } to->b_instr[n] = from->b_instr[i]; } return SUCCESS; } static inline int basicblock_nofallthrough(const basicblock *b) { cfg_instr *last = basicblock_last_instr(b); return (last && (IS_SCOPE_EXIT_OPCODE(last->i_opcode) || IS_UNCONDITIONAL_JUMP_OPCODE(last->i_opcode))); } #define BB_NO_FALLTHROUGH(B) (basicblock_nofallthrough(B)) #define BB_HAS_FALLTHROUGH(B) (!basicblock_nofallthrough(B)) static basicblock * copy_basicblock(cfg_builder *g, basicblock *block) { /* Cannot copy a block if it has a fallthrough, since * a block can only have one fallthrough predecessor. */ assert(BB_NO_FALLTHROUGH(block)); basicblock *result = cfg_builder_new_block(g); if (result == NULL) { return NULL; } if (basicblock_append_instructions(result, block) < 0) { return NULL; } return result; } static int basicblock_insert_instruction(basicblock *block, int pos, cfg_instr *instr) { RETURN_IF_ERROR(basicblock_next_instr(block)); for (int i = block->b_iused - 1; i > pos; i--) { block->b_instr[i] = block->b_instr[i-1]; } block->b_instr[pos] = *instr; return SUCCESS; } /* For debugging purposes only */ #if 0 static void dump_instr(cfg_instr *i) { const char *jump = is_jump(i) ? "jump " : ""; char arg[128]; *arg = '\0'; if (OPCODE_HAS_ARG(i->i_opcode)) { sprintf(arg, "arg: %d ", i->i_oparg); } if (HAS_TARGET(i->i_opcode)) { sprintf(arg, "target: %p [%d] ", i->i_target, i->i_oparg); } fprintf(stderr, "line: %d, %s (%d) %s%s\n", i->i_loc.lineno, _PyOpcode_OpName[i->i_opcode], i->i_opcode, arg, jump); } static inline int basicblock_returns(const basicblock *b) { cfg_instr *last = basicblock_last_instr(b); return last && IS_RETURN_OPCODE(last->i_opcode); } static void dump_basicblock(const basicblock *b, bool highlight) { const char *b_return = basicblock_returns(b) ? "return " : ""; if (highlight) { fprintf(stderr, ">>> "); } fprintf(stderr, "%d: [EH=%d CLD=%d WRM=%d NO_FT=%d %p] used: %d, depth: %d, preds: %d %s\n", b->b_label.id, b->b_except_handler, b->b_cold, b->b_warm, BB_NO_FALLTHROUGH(b), b, b->b_iused, b->b_startdepth, b->b_predecessors, b_return); int depth = b->b_startdepth; if (b->b_instr) { int i; for (i = 0; i < b->b_iused; i++) { fprintf(stderr, " [%02d] depth: %d ", i, depth); dump_instr(b->b_instr + i); int popped = _PyOpcode_num_popped(b->b_instr[i].i_opcode, b->b_instr[i].i_oparg); int pushed = _PyOpcode_num_pushed(b->b_instr[i].i_opcode, b->b_instr[i].i_oparg); depth += (pushed - popped); } } } void _PyCfgBuilder_DumpGraph(const basicblock *entryblock, const basicblock *mark) { for (const basicblock *b = entryblock; b != NULL; b = b->b_next) { dump_basicblock(b, b == mark); } } #endif /***** CFG construction and modification *****/ static basicblock * cfg_builder_use_next_block(cfg_builder *g, basicblock *block) { assert(block != NULL); g->g_curblock->b_next = block; g->g_curblock = block; return block; } static inline int basicblock_exits_scope(const basicblock *b) { cfg_instr *last = basicblock_last_instr(b); return last && IS_SCOPE_EXIT_OPCODE(last->i_opcode); } static inline int basicblock_has_eval_break(const basicblock *b) { for (int i = 0; i < b->b_iused; i++) { if (OPCODE_HAS_EVAL_BREAK(b->b_instr[i].i_opcode)) { return true; } } return false; } static bool cfg_builder_current_block_is_terminated(cfg_builder *g) { cfg_instr *last = basicblock_last_instr(g->g_curblock); if (last && IS_TERMINATOR_OPCODE(last->i_opcode)) { return true; } if (IS_LABEL(g->g_current_label)) { if (last || IS_LABEL(g->g_curblock->b_label)) { return true; } else { /* current block is empty, label it */ g->g_curblock->b_label = g->g_current_label; g->g_current_label = NO_LABEL; } } return false; } static int cfg_builder_maybe_start_new_block(cfg_builder *g) { if (cfg_builder_current_block_is_terminated(g)) { basicblock *b = cfg_builder_new_block(g); if (b == NULL) { return ERROR; } b->b_label = g->g_current_label; g->g_current_label = NO_LABEL; cfg_builder_use_next_block(g, b); } return SUCCESS; } #ifndef NDEBUG static bool cfg_builder_check(cfg_builder *g) { for (basicblock *block = g->g_block_list; block != NULL; block = block->b_list) { assert(!_PyMem_IsPtrFreed(block)); if (block->b_instr != NULL) { assert(block->b_ialloc > 0); assert(block->b_iused >= 0); assert(block->b_ialloc >= block->b_iused); } else { assert (block->b_iused == 0); assert (block->b_ialloc == 0); } } return true; } #endif static int init_cfg_builder(cfg_builder *g) { g->g_block_list = NULL; basicblock *block = cfg_builder_new_block(g); if (block == NULL) { return ERROR; } g->g_curblock = g->g_entryblock = block; g->g_current_label = NO_LABEL; return SUCCESS; } cfg_builder * _PyCfgBuilder_New(void) { cfg_builder *g = PyMem_Malloc(sizeof(cfg_builder)); if (g == NULL) { PyErr_NoMemory(); return NULL; } memset(g, 0, sizeof(cfg_builder)); if (init_cfg_builder(g) < 0) { PyMem_Free(g); return NULL; } return g; } void _PyCfgBuilder_Free(cfg_builder *g) { if (g == NULL) { return; } assert(cfg_builder_check(g)); basicblock *b = g->g_block_list; while (b != NULL) { if (b->b_instr) { PyMem_Free((void *)b->b_instr); } basicblock *next = b->b_list; PyMem_Free((void *)b); b = next; } PyMem_Free(g); } int _PyCfgBuilder_CheckSize(cfg_builder *g) { int nblocks = 0; for (basicblock *b = g->g_block_list; b != NULL; b = b->b_list) { nblocks++; } if ((size_t)nblocks > SIZE_MAX / sizeof(basicblock *)) { PyErr_NoMemory(); return ERROR; } return SUCCESS; } int _PyCfgBuilder_UseLabel(cfg_builder *g, jump_target_label lbl) { g->g_current_label = lbl; return cfg_builder_maybe_start_new_block(g); } int _PyCfgBuilder_Addop(cfg_builder *g, int opcode, int oparg, location loc) { RETURN_IF_ERROR(cfg_builder_maybe_start_new_block(g)); return basicblock_addop(g->g_curblock, opcode, oparg, loc, NULL); } static basicblock * next_nonempty_block(basicblock *b) { while (b && b->b_iused == 0) { b = b->b_next; } return b; } /***** debugging helpers *****/ #ifndef NDEBUG static int remove_redundant_nops(cfg_builder *g); static bool no_redundant_nops(cfg_builder *g) { if (remove_redundant_nops(g) != 0) { return false; } return true; } static bool no_redundant_jumps(cfg_builder *g) { for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { cfg_instr *last = basicblock_last_instr(b); if (last != NULL) { if (IS_UNCONDITIONAL_JUMP_OPCODE(last->i_opcode)) { basicblock *next = next_nonempty_block(b->b_next); basicblock *jump_target = next_nonempty_block(last->i_target); if (jump_target == next) { assert(next); if (last->i_loc.lineno == next->b_instr[0].i_loc.lineno) { assert(0); return false; } } } } } return true; } #endif /***** CFG preprocessing (jump targets and exceptions) *****/ static int normalize_jumps_in_block(cfg_builder *g, basicblock *b) { cfg_instr *last = basicblock_last_instr(b); if (last == NULL || !IS_CONDITIONAL_JUMP_OPCODE(last->i_opcode)) { return SUCCESS; } assert(!IS_ASSEMBLER_OPCODE(last->i_opcode)); bool is_forward = last->i_target->b_visited == 0; if (is_forward) { RETURN_IF_ERROR( basicblock_addop(b, NOT_TAKEN, 0, last->i_loc, last->i_except)); return SUCCESS; } int reversed_opcode = 0; switch(last->i_opcode) { case POP_JUMP_IF_NOT_NONE: reversed_opcode = POP_JUMP_IF_NONE; break; case POP_JUMP_IF_NONE: reversed_opcode = POP_JUMP_IF_NOT_NONE; break; case POP_JUMP_IF_FALSE: reversed_opcode = POP_JUMP_IF_TRUE; break; case POP_JUMP_IF_TRUE: reversed_opcode = POP_JUMP_IF_FALSE; break; } /* transform 'conditional jump T' to * 'reversed_jump b_next' followed by 'jump_backwards T' */ basicblock *target = last->i_target; basicblock *backwards_jump = cfg_builder_new_block(g); if (backwards_jump == NULL) { return ERROR; } RETURN_IF_ERROR( basicblock_addop(backwards_jump, NOT_TAKEN, 0, last->i_loc, last->i_except)); RETURN_IF_ERROR( basicblock_add_jump(backwards_jump, JUMP, target, last->i_loc, last->i_except)); backwards_jump->b_startdepth = target->b_startdepth; last->i_opcode = reversed_opcode; last->i_target = b->b_next; backwards_jump->b_cold = b->b_cold; backwards_jump->b_next = b->b_next; b->b_next = backwards_jump; return SUCCESS; } static int normalize_jumps(cfg_builder *g) { basicblock *entryblock = g->g_entryblock; for (basicblock *b = entryblock; b != NULL; b = b->b_next) { b->b_visited = 0; } for (basicblock *b = entryblock; b != NULL; b = b->b_next) { b->b_visited = 1; RETURN_IF_ERROR(normalize_jumps_in_block(g, b)); } return SUCCESS; } static int check_cfg(cfg_builder *g) { for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { /* Raise SystemError if jump or exit is not last instruction in the block. */ for (int i = 0; i < b->b_iused; i++) { int opcode = b->b_instr[i].i_opcode; assert(!IS_ASSEMBLER_OPCODE(opcode)); if (IS_TERMINATOR_OPCODE(opcode)) { if (i != b->b_iused - 1) { PyErr_SetString(PyExc_SystemError, "malformed control flow graph."); return ERROR; } } } } return SUCCESS; } static int get_max_label(basicblock *entryblock) { int lbl = -1; for (basicblock *b = entryblock; b != NULL; b = b->b_next) { if (b->b_label.id > lbl) { lbl = b->b_label.id; } } return lbl; } /* Calculate the actual jump target from the target_label */ static int translate_jump_labels_to_targets(basicblock *entryblock) { int max_label = get_max_label(entryblock); size_t mapsize = sizeof(basicblock *) * (max_label + 1); basicblock **label2block = (basicblock **)PyMem_Malloc(mapsize); if (!label2block) { PyErr_NoMemory(); return ERROR; } memset(label2block, 0, mapsize); for (basicblock *b = entryblock; b != NULL; b = b->b_next) { if (b->b_label.id >= 0) { label2block[b->b_label.id] = b; } } for (basicblock *b = entryblock; b != NULL; b = b->b_next) { for (int i = 0; i < b->b_iused; i++) { cfg_instr *instr = &b->b_instr[i]; assert(instr->i_target == NULL); if (HAS_TARGET(instr->i_opcode)) { int lbl = instr->i_oparg; assert(lbl >= 0 && lbl <= max_label); instr->i_target = label2block[lbl]; assert(instr->i_target != NULL); assert(instr->i_target->b_label.id == lbl); } } } PyMem_Free(label2block); return SUCCESS; } static int mark_except_handlers(basicblock *entryblock) { #ifndef NDEBUG for (basicblock *b = entryblock; b != NULL; b = b->b_next) { assert(!b->b_except_handler); } #endif for (basicblock *b = entryblock; b != NULL; b = b->b_next) { for (int i=0; i < b->b_iused; i++) { cfg_instr *instr = &b->b_instr[i]; if (is_block_push(instr)) { instr->i_target->b_except_handler = 1; } } } return SUCCESS; } struct _PyCfgExceptStack { basicblock *handlers[CO_MAXBLOCKS+2]; int depth; }; static basicblock * push_except_block(struct _PyCfgExceptStack *stack, cfg_instr *setup) { assert(is_block_push(setup)); int opcode = setup->i_opcode; basicblock * target = setup->i_target; if (opcode == SETUP_WITH || opcode == SETUP_CLEANUP) { target->b_preserve_lasti = 1; } assert(stack->depth <= CO_MAXBLOCKS); stack->handlers[++stack->depth] = target; return target; } static basicblock * pop_except_block(struct _PyCfgExceptStack *stack) { assert(stack->depth > 0); return stack->handlers[--stack->depth]; } static basicblock * except_stack_top(struct _PyCfgExceptStack *stack) { return stack->handlers[stack->depth]; } static struct _PyCfgExceptStack * make_except_stack(void) { struct _PyCfgExceptStack *new = PyMem_Malloc(sizeof(struct _PyCfgExceptStack)); if (new == NULL) { PyErr_NoMemory(); return NULL; } new->depth = 0; new->handlers[0] = NULL; return new; } static struct _PyCfgExceptStack * copy_except_stack(struct _PyCfgExceptStack *stack) { struct _PyCfgExceptStack *copy = PyMem_Malloc(sizeof(struct _PyCfgExceptStack)); if (copy == NULL) { PyErr_NoMemory(); return NULL; } memcpy(copy, stack, sizeof(struct _PyCfgExceptStack)); return copy; } static basicblock** make_cfg_traversal_stack(basicblock *entryblock) { int nblocks = 0; for (basicblock *b = entryblock; b != NULL; b = b->b_next) { b->b_visited = 0; nblocks++; } basicblock **stack = (basicblock **)PyMem_Malloc(sizeof(basicblock *) * nblocks); if (!stack) { PyErr_NoMemory(); } return stack; } /* Compute the stack effects of opcode with argument oparg. Some opcodes have different stack effect when jump to the target and when not jump. The 'jump' parameter specifies the case: * 0 -- when not jump * 1 -- when jump * -1 -- maximal */ typedef struct { /* The stack effect of the instruction. */ int net; } stack_effects; Py_LOCAL(int) get_stack_effects(int opcode, int oparg, int jump, stack_effects *effects) { if (opcode < 0) { return -1; } if ((opcode <= MAX_REAL_OPCODE) && (_PyOpcode_Deopt[opcode] != opcode)) { // Specialized instructions are not supported. return -1; } int popped = _PyOpcode_num_popped(opcode, oparg); int pushed = _PyOpcode_num_pushed(opcode, oparg); if (popped < 0 || pushed < 0) { return -1; } if (IS_BLOCK_PUSH_OPCODE(opcode) && !jump) { effects->net = 0; return 0; } effects->net = pushed - popped; return 0; } Py_LOCAL_INLINE(int) stackdepth_push(basicblock ***sp, basicblock *b, int depth) { if (!(b->b_startdepth < 0 || b->b_startdepth == depth)) { PyErr_Format(PyExc_ValueError, "Invalid CFG, inconsistent stackdepth"); return ERROR; } if (b->b_startdepth < depth && b->b_startdepth < 100) { assert(b->b_startdepth < 0); b->b_startdepth = depth; *(*sp)++ = b; } return SUCCESS; } /* Find the flow path that needs the largest stack. We assume that * cycles in the flow graph have no net effect on the stack depth. */ static int calculate_stackdepth(cfg_builder *g) { basicblock *entryblock = g->g_entryblock; for (basicblock *b = entryblock; b != NULL; b = b->b_next) { b->b_startdepth = INT_MIN; } basicblock **stack = make_cfg_traversal_stack(entryblock); if (!stack) { return ERROR; } int stackdepth = -1; int maxdepth = 0; basicblock **sp = stack; if (stackdepth_push(&sp, entryblock, 0) < 0) { goto error; } while (sp != stack) { basicblock *b = *--sp; int depth = b->b_startdepth; assert(depth >= 0); basicblock *next = b->b_next; for (int i = 0; i < b->b_iused; i++) { cfg_instr *instr = &b->b_instr[i]; stack_effects effects; if (get_stack_effects(instr->i_opcode, instr->i_oparg, 0, &effects) < 0) { PyErr_Format(PyExc_SystemError, "Invalid stack effect for opcode=%d, arg=%i", instr->i_opcode, instr->i_oparg); goto error; } int new_depth = depth + effects.net; if (new_depth < 0) { PyErr_Format(PyExc_ValueError, "Invalid CFG, stack underflow at line %d", instr->i_loc.lineno); goto error; } maxdepth = Py_MAX(maxdepth, depth); if (HAS_TARGET(instr->i_opcode) && instr->i_opcode != END_ASYNC_FOR) { if (get_stack_effects(instr->i_opcode, instr->i_oparg, 1, &effects) < 0) { PyErr_Format(PyExc_SystemError, "Invalid stack effect for opcode=%d, arg=%i", instr->i_opcode, instr->i_oparg); goto error; } int target_depth = depth + effects.net; assert(target_depth >= 0); /* invalid code or bug in stackdepth() */ maxdepth = Py_MAX(maxdepth, depth); if (stackdepth_push(&sp, instr->i_target, target_depth) < 0) { goto error; } } depth = new_depth; assert(!IS_ASSEMBLER_OPCODE(instr->i_opcode)); if (IS_UNCONDITIONAL_JUMP_OPCODE(instr->i_opcode) || IS_SCOPE_EXIT_OPCODE(instr->i_opcode)) { /* remaining code is dead */ next = NULL; break; } } if (next != NULL) { assert(BB_HAS_FALLTHROUGH(b)); if (stackdepth_push(&sp, next, depth) < 0) { goto error; } } } stackdepth = maxdepth; error: PyMem_Free(stack); return stackdepth; } static int label_exception_targets(basicblock *entryblock) { basicblock **todo_stack = make_cfg_traversal_stack(entryblock); if (todo_stack == NULL) { return ERROR; } struct _PyCfgExceptStack *except_stack = make_except_stack(); if (except_stack == NULL) { PyMem_Free(todo_stack); PyErr_NoMemory(); return ERROR; } except_stack->depth = 0; todo_stack[0] = entryblock; entryblock->b_visited = 1; entryblock->b_exceptstack = except_stack; basicblock **todo = &todo_stack[1]; basicblock *handler = NULL; while (todo > todo_stack) { todo--; basicblock *b = todo[0]; assert(b->b_visited == 1); except_stack = b->b_exceptstack; assert(except_stack != NULL); b->b_exceptstack = NULL; handler = except_stack_top(except_stack); int last_yield_except_depth = -1; for (int i = 0; i < b->b_iused; i++) { cfg_instr *instr = &b->b_instr[i]; if (is_block_push(instr)) { if (!instr->i_target->b_visited) { struct _PyCfgExceptStack *copy = copy_except_stack(except_stack); if (copy == NULL) { goto error; } instr->i_target->b_exceptstack = copy; todo[0] = instr->i_target; instr->i_target->b_visited = 1; todo++; } handler = push_except_block(except_stack, instr); } else if (instr->i_opcode == POP_BLOCK) { handler = pop_except_block(except_stack); INSTR_SET_OP0(instr, NOP); } else if (is_jump(instr)) { instr->i_except = handler; assert(i == b->b_iused -1); if (!instr->i_target->b_visited) { if (BB_HAS_FALLTHROUGH(b)) { struct _PyCfgExceptStack *copy = copy_except_stack(except_stack); if (copy == NULL) { goto error; } instr->i_target->b_exceptstack = copy; } else { instr->i_target->b_exceptstack = except_stack; except_stack = NULL; } todo[0] = instr->i_target; instr->i_target->b_visited = 1; todo++; } } else if (instr->i_opcode == YIELD_VALUE) { instr->i_except = handler; last_yield_except_depth = except_stack->depth; } else if (instr->i_opcode == RESUME) { instr->i_except = handler; if (instr->i_oparg != RESUME_AT_FUNC_START && instr->i_oparg != RESUME_AT_GEN_EXPR_START) { assert(last_yield_except_depth >= 0); if (last_yield_except_depth == 1) { instr->i_oparg |= RESUME_OPARG_DEPTH1_MASK; } last_yield_except_depth = -1; } } else if (instr->i_opcode == RETURN_GENERATOR) { instr->i_except = NULL; } else { instr->i_except = handler; } } if (BB_HAS_FALLTHROUGH(b) && !b->b_next->b_visited) { assert(except_stack != NULL); b->b_next->b_exceptstack = except_stack; todo[0] = b->b_next; b->b_next->b_visited = 1; todo++; } else if (except_stack != NULL) { PyMem_Free(except_stack); } } #ifdef Py_DEBUG for (basicblock *b = entryblock; b != NULL; b = b->b_next) { assert(b->b_exceptstack == NULL); |
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