1 /* Expands front end tree to back end RTL for GCC 2 Copyright (C) 1987-2018 Free Software Foundation, Inc. 3 4 This file is part of GCC. 5 6 GCC is free software; you can redistribute it and/or modify it under 7 the terms of the GNU General Public License as published by the Free 8 Software Foundation; either version 3, or (at your option) any later 9 version. 10 11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12 WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GCC; see the file COPYING3. If not see 18 <http://www.gnu.org/licenses/>. */ 19 20 /* This file handles the generation of rtl code from tree structure 21 above the level of expressions, using subroutines in exp*.c and emit-rtl.c. 22 The functions whose names start with `expand_' are called by the 23 expander to generate RTL instructions for various kinds of constructs. */ 24 25 #include "config.h" 26 #include "system.h" 27 #include "coretypes.h" 28 #include "backend.h" 29 #include "target.h" 30 #include "rtl.h" 31 #include "tree.h" 32 #include "gimple.h" 33 #include "cfghooks.h" 34 #include "predict.h" 35 #include "memmodel.h" 36 #include "tm_p.h" 37 #include "optabs.h" 38 #include "regs.h" 39 #include "emit-rtl.h" 40 #include "pretty-print.h" 41 #include "diagnostic-core.h" 42 43 #include "fold-const.h" 44 #include "varasm.h" 45 #include "stor-layout.h" 46 #include "dojump.h" 47 #include "explow.h" 48 #include "stmt.h" 49 #include "expr.h" 50 #include "langhooks.h" 51 #include "cfganal.h" 52 #include "tree-cfg.h" 53 #include "params.h" 54 #include "dumpfile.h" 55 #include "builtins.h" 56 57 58 /* Functions and data structures for expanding case statements. */ 59 60 /* Case label structure, used to hold info on labels within case 61 statements. We handle "range" labels; for a single-value label 62 as in C, the high and low limits are the same. 63 64 We start with a vector of case nodes sorted in ascending order, and 65 the default label as the last element in the vector. 66 67 Switch statements are expanded in jump table form. 68 69 */ 70 71 struct simple_case_node 72 { 73 simple_case_node (tree low, tree high, tree code_label): 74 m_low (low), m_high (high), m_code_label (code_label) 75 {} 76 77 /* Lowest index value for this label. */ 78 tree m_low; 79 /* Highest index value for this label. */ 80 tree m_high; 81 /* Label to jump to when node matches. */ 82 tree m_code_label; 83 }; 84 85 extern basic_block label_to_block_fn (struct function *, tree); 86 87 static bool check_unique_operand_names (tree, tree, tree); 88 static char *resolve_operand_name_1 (char *, tree, tree, tree); 89 90 /* Return the rtx-label that corresponds to a LABEL_DECL, 91 creating it if necessary. */ 92 93 rtx_insn * 94 label_rtx (tree label) 95 { 96 gcc_assert (TREE_CODE (label) == LABEL_DECL); 97 98 if (!DECL_RTL_SET_P (label)) 99 { 100 rtx_code_label *r = gen_label_rtx (); 101 SET_DECL_RTL (label, r); 102 if (FORCED_LABEL (label) || DECL_NONLOCAL (label)) 103 LABEL_PRESERVE_P (r) = 1; 104 } 105 106 return as_a <rtx_insn *> (DECL_RTL (label)); 107 } 108 109 /* As above, but also put it on the forced-reference list of the 110 function that contains it. */ 111 rtx_insn * 112 force_label_rtx (tree label) 113 { 114 rtx_insn *ref = label_rtx (label); 115 tree function = decl_function_context (label); 116 117 gcc_assert (function); 118 119 vec_safe_push (forced_labels, ref); 120 return ref; 121 } 122 123 /* As label_rtx, but ensures (in check build), that returned value is 124 an existing label (i.e. rtx with code CODE_LABEL). */ 125 rtx_code_label * 126 jump_target_rtx (tree label) 127 { 128 return as_a <rtx_code_label *> (label_rtx (label)); 129 } 130 131 /* Add an unconditional jump to LABEL as the next sequential instruction. */ 132 133 void 134 emit_jump (rtx label) 135 { 136 do_pending_stack_adjust (); 137 emit_jump_insn (targetm.gen_jump (label)); 138 emit_barrier (); 139 } 140 141 /* Handle goto statements and the labels that they can go to. */ 142 143 /* Specify the location in the RTL code of a label LABEL, 144 which is a LABEL_DECL tree node. 145 146 This is used for the kind of label that the user can jump to with a 147 goto statement, and for alternatives of a switch or case statement. 148 RTL labels generated for loops and conditionals don't go through here; 149 they are generated directly at the RTL level, by other functions below. 150 151 Note that this has nothing to do with defining label *names*. 152 Languages vary in how they do that and what that even means. */ 153 154 void 155 expand_label (tree label) 156 { 157 rtx_code_label *label_r = jump_target_rtx (label); 158 159 do_pending_stack_adjust (); 160 emit_label (label_r); 161 if (DECL_NAME (label)) 162 LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label)); 163 164 if (DECL_NONLOCAL (label)) 165 { 166 expand_builtin_setjmp_receiver (NULL); 167 nonlocal_goto_handler_labels 168 = gen_rtx_INSN_LIST (VOIDmode, label_r, 169 nonlocal_goto_handler_labels); 170 } 171 172 if (FORCED_LABEL (label)) 173 vec_safe_push<rtx_insn *> (forced_labels, label_r); 174 175 if (DECL_NONLOCAL (label) || FORCED_LABEL (label)) 176 maybe_set_first_label_num (label_r); 177 } 178 179 /* Parse the output constraint pointed to by *CONSTRAINT_P. It is the 180 OPERAND_NUMth output operand, indexed from zero. There are NINPUTS 181 inputs and NOUTPUTS outputs to this extended-asm. Upon return, 182 *ALLOWS_MEM will be TRUE iff the constraint allows the use of a 183 memory operand. Similarly, *ALLOWS_REG will be TRUE iff the 184 constraint allows the use of a register operand. And, *IS_INOUT 185 will be true if the operand is read-write, i.e., if it is used as 186 an input as well as an output. If *CONSTRAINT_P is not in 187 canonical form, it will be made canonical. (Note that `+' will be 188 replaced with `=' as part of this process.) 189 190 Returns TRUE if all went well; FALSE if an error occurred. */ 191 192 bool 193 parse_output_constraint (const char **constraint_p, int operand_num, 194 int ninputs, int noutputs, bool *allows_mem, 195 bool *allows_reg, bool *is_inout) 196 { 197 const char *constraint = *constraint_p; 198 const char *p; 199 200 /* Assume the constraint doesn't allow the use of either a register 201 or memory. */ 202 *allows_mem = false; 203 *allows_reg = false; 204 205 /* Allow the `=' or `+' to not be at the beginning of the string, 206 since it wasn't explicitly documented that way, and there is a 207 large body of code that puts it last. Swap the character to 208 the front, so as not to uglify any place else. */ 209 p = strchr (constraint, '='); 210 if (!p) 211 p = strchr (constraint, '+'); 212 213 /* If the string doesn't contain an `=', issue an error 214 message. */ 215 if (!p) 216 { 217 error ("output operand constraint lacks %<=%>"); 218 return false; 219 } 220 221 /* If the constraint begins with `+', then the operand is both read 222 from and written to. */ 223 *is_inout = (*p == '+'); 224 225 /* Canonicalize the output constraint so that it begins with `='. */ 226 if (p != constraint || *is_inout) 227 { 228 char *buf; 229 size_t c_len = strlen (constraint); 230 231 if (p != constraint) 232 warning (0, "output constraint %qc for operand %d " 233 "is not at the beginning", 234 *p, operand_num); 235 236 /* Make a copy of the constraint. */ 237 buf = XALLOCAVEC (char, c_len + 1); 238 strcpy (buf, constraint); 239 /* Swap the first character and the `=' or `+'. */ 240 buf[p - constraint] = buf[0]; 241 /* Make sure the first character is an `='. (Until we do this, 242 it might be a `+'.) */ 243 buf[0] = '='; 244 /* Replace the constraint with the canonicalized string. */ 245 *constraint_p = ggc_alloc_string (buf, c_len); 246 constraint = *constraint_p; 247 } 248 249 /* Loop through the constraint string. */ 250 for (p = constraint + 1; *p; ) 251 { 252 switch (*p) 253 { 254 case '+': 255 case '=': 256 error ("operand constraint contains incorrectly positioned " 257 "%<+%> or %<=%>"); 258 return false; 259 260 case '%': 261 if (operand_num + 1 == ninputs + noutputs) 262 { 263 error ("%<%%%> constraint used with last operand"); 264 return false; 265 } 266 break; 267 268 case '?': case '!': case '*': case '&': case '#': 269 case '$': case '^': 270 case 'E': case 'F': case 'G': case 'H': 271 case 's': case 'i': case 'n': 272 case 'I': case 'J': case 'K': case 'L': case 'M': 273 case 'N': case 'O': case 'P': case ',': 274 break; 275 276 case '0': case '1': case '2': case '3': case '4': 277 case '5': case '6': case '7': case '8': case '9': 278 case '[': 279 error ("matching constraint not valid in output operand"); 280 return false; 281 282 case '<': case '>': 283 /* ??? Before flow, auto inc/dec insns are not supposed to exist, 284 excepting those that expand_call created. So match memory 285 and hope. */ 286 *allows_mem = true; 287 break; 288 289 case 'g': case 'X': 290 *allows_reg = true; 291 *allows_mem = true; 292 break; 293 294 default: 295 if (!ISALPHA (*p)) 296 break; 297 enum constraint_num cn = lookup_constraint (p); 298 if (reg_class_for_constraint (cn) != NO_REGS 299 || insn_extra_address_constraint (cn)) 300 *allows_reg = true; 301 else if (insn_extra_memory_constraint (cn)) 302 *allows_mem = true; 303 else 304 insn_extra_constraint_allows_reg_mem (cn, allows_reg, allows_mem); 305 break; 306 } 307 308 for (size_t len = CONSTRAINT_LEN (*p, p); len; len--, p++) 309 if (*p == '\0') 310 break; 311 } 312 313 return true; 314 } 315 316 /* Similar, but for input constraints. */ 317 318 bool 319 parse_input_constraint (const char **constraint_p, int input_num, 320 int ninputs, int noutputs, int ninout, 321 const char * const * constraints, 322 bool *allows_mem, bool *allows_reg) 323 { 324 const char *constraint = *constraint_p; 325 const char *orig_constraint = constraint; 326 size_t c_len = strlen (constraint); 327 size_t j; 328 bool saw_match = false; 329 330 /* Assume the constraint doesn't allow the use of either 331 a register or memory. */ 332 *allows_mem = false; 333 *allows_reg = false; 334 335 /* Make sure constraint has neither `=', `+', nor '&'. */ 336 337 for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j)) 338 switch (constraint[j]) 339 { 340 case '+': case '=': case '&': 341 if (constraint == orig_constraint) 342 { 343 error ("input operand constraint contains %qc", constraint[j]); 344 return false; 345 } 346 break; 347 348 case '%': 349 if (constraint == orig_constraint 350 && input_num + 1 == ninputs - ninout) 351 { 352 error ("%<%%%> constraint used with last operand"); 353 return false; 354 } 355 break; 356 357 case '<': case '>': 358 case '?': case '!': case '*': case '#': 359 case '$': case '^': 360 case 'E': case 'F': case 'G': case 'H': 361 case 's': case 'i': case 'n': 362 case 'I': case 'J': case 'K': case 'L': case 'M': 363 case 'N': case 'O': case 'P': case ',': 364 break; 365 366 /* Whether or not a numeric constraint allows a register is 367 decided by the matching constraint, and so there is no need 368 to do anything special with them. We must handle them in 369 the default case, so that we don't unnecessarily force 370 operands to memory. */ 371 case '0': case '1': case '2': case '3': case '4': 372 case '5': case '6': case '7': case '8': case '9': 373 { 374 char *end; 375 unsigned long match; 376 377 saw_match = true; 378 379 match = strtoul (constraint + j, &end, 10); 380 if (match >= (unsigned long) noutputs) 381 { 382 error ("matching constraint references invalid operand number"); 383 return false; 384 } 385 386 /* Try and find the real constraint for this dup. Only do this 387 if the matching constraint is the only alternative. */ 388 if (*end == '\0' 389 && (j == 0 || (j == 1 && constraint[0] == '%'))) 390 { 391 constraint = constraints[match]; 392 *constraint_p = constraint; 393 c_len = strlen (constraint); 394 j = 0; 395 /* ??? At the end of the loop, we will skip the first part of 396 the matched constraint. This assumes not only that the 397 other constraint is an output constraint, but also that 398 the '=' or '+' come first. */ 399 break; 400 } 401 else 402 j = end - constraint; 403 /* Anticipate increment at end of loop. */ 404 j--; 405 } 406 /* Fall through. */ 407 408 case 'g': case 'X': 409 *allows_reg = true; 410 *allows_mem = true; 411 break; 412 413 default: 414 if (! ISALPHA (constraint[j])) 415 { 416 error ("invalid punctuation %qc in constraint", constraint[j]); 417 return false; 418 } 419 enum constraint_num cn = lookup_constraint (constraint + j); 420 if (reg_class_for_constraint (cn) != NO_REGS 421 || insn_extra_address_constraint (cn)) 422 *allows_reg = true; 423 else if (insn_extra_memory_constraint (cn) 424 || insn_extra_special_memory_constraint (cn)) 425 *allows_mem = true; 426 else 427 insn_extra_constraint_allows_reg_mem (cn, allows_reg, allows_mem); 428 break; 429 } 430 431 if (saw_match && !*allows_reg) 432 warning (0, "matching constraint does not allow a register"); 433 434 return true; 435 } 436 437 /* Return DECL iff there's an overlap between *REGS and DECL, where DECL 438 can be an asm-declared register. Called via walk_tree. */ 439 440 static tree 441 decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED, 442 void *data) 443 { 444 tree decl = *declp; 445 const HARD_REG_SET *const regs = (const HARD_REG_SET *) data; 446 447 if (VAR_P (decl)) 448 { 449 if (DECL_HARD_REGISTER (decl) 450 && REG_P (DECL_RTL (decl)) 451 && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER) 452 { 453 rtx reg = DECL_RTL (decl); 454 455 if (overlaps_hard_reg_set_p (*regs, GET_MODE (reg), REGNO (reg))) 456 return decl; 457 } 458 walk_subtrees = 0; 459 } 460 else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL) 461 walk_subtrees = 0; 462 return NULL_TREE; 463 } 464 465 /* If there is an overlap between *REGS and DECL, return the first overlap 466 found. */ 467 tree 468 tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs) 469 { 470 return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL); 471 } 472 473 474 /* A subroutine of expand_asm_operands. Check that all operand names 475 are unique. Return true if so. We rely on the fact that these names 476 are identifiers, and so have been canonicalized by get_identifier, 477 so all we need are pointer comparisons. */ 478 479 static bool 480 check_unique_operand_names (tree outputs, tree inputs, tree labels) 481 { 482 tree i, j, i_name = NULL_TREE; 483 484 for (i = outputs; i ; i = TREE_CHAIN (i)) 485 { 486 i_name = TREE_PURPOSE (TREE_PURPOSE (i)); 487 if (! i_name) 488 continue; 489 490 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j)) 491 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) 492 goto failure; 493 } 494 495 for (i = inputs; i ; i = TREE_CHAIN (i)) 496 { 497 i_name = TREE_PURPOSE (TREE_PURPOSE (i)); 498 if (! i_name) 499 continue; 500 501 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j)) 502 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) 503 goto failure; 504 for (j = outputs; j ; j = TREE_CHAIN (j)) 505 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) 506 goto failure; 507 } 508 509 for (i = labels; i ; i = TREE_CHAIN (i)) 510 { 511 i_name = TREE_PURPOSE (i); 512 if (! i_name) 513 continue; 514 515 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j)) 516 if (simple_cst_equal (i_name, TREE_PURPOSE (j))) 517 goto failure; 518 for (j = inputs; j ; j = TREE_CHAIN (j)) 519 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) 520 goto failure; 521 } 522 523 return true; 524 525 failure: 526 error ("duplicate asm operand name %qs", TREE_STRING_POINTER (i_name)); 527 return false; 528 } 529 530 /* Resolve the names of the operands in *POUTPUTS and *PINPUTS to numbers, 531 and replace the name expansions in STRING and in the constraints to 532 those numbers. This is generally done in the front end while creating 533 the ASM_EXPR generic tree that eventually becomes the GIMPLE_ASM. */ 534 535 tree 536 resolve_asm_operand_names (tree string, tree outputs, tree inputs, tree labels) 537 { 538 char *buffer; 539 char *p; 540 const char *c; 541 tree t; 542 543 check_unique_operand_names (outputs, inputs, labels); 544 545 /* Substitute [<name>] in input constraint strings. There should be no 546 named operands in output constraints. */ 547 for (t = inputs; t ; t = TREE_CHAIN (t)) 548 { 549 c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t))); 550 if (strchr (c, '[') != NULL) 551 { 552 p = buffer = xstrdup (c); 553 while ((p = strchr (p, '[')) != NULL) 554 p = resolve_operand_name_1 (p, outputs, inputs, NULL); 555 TREE_VALUE (TREE_PURPOSE (t)) 556 = build_string (strlen (buffer), buffer); 557 free (buffer); 558 } 559 } 560 561 /* Now check for any needed substitutions in the template. */ 562 c = TREE_STRING_POINTER (string); 563 while ((c = strchr (c, '%')) != NULL) 564 { 565 if (c[1] == '[') 566 break; 567 else if (ISALPHA (c[1]) && c[2] == '[') 568 break; 569 else 570 { 571 c += 1 + (c[1] == '%'); 572 continue; 573 } 574 } 575 576 if (c) 577 { 578 /* OK, we need to make a copy so we can perform the substitutions. 579 Assume that we will not need extra space--we get to remove '[' 580 and ']', which means we cannot have a problem until we have more 581 than 999 operands. */ 582 buffer = xstrdup (TREE_STRING_POINTER (string)); 583 p = buffer + (c - TREE_STRING_POINTER (string)); 584 585 while ((p = strchr (p, '%')) != NULL) 586 { 587 if (p[1] == '[') 588 p += 1; 589 else if (ISALPHA (p[1]) && p[2] == '[') 590 p += 2; 591 else 592 { 593 p += 1 + (p[1] == '%'); 594 continue; 595 } 596 597 p = resolve_operand_name_1 (p, outputs, inputs, labels); 598 } 599 600 string = build_string (strlen (buffer), buffer); 601 free (buffer); 602 } 603 604 return string; 605 } 606 607 /* A subroutine of resolve_operand_names. P points to the '[' for a 608 potential named operand of the form [<name>]. In place, replace 609 the name and brackets with a number. Return a pointer to the 610 balance of the string after substitution. */ 611 612 static char * 613 resolve_operand_name_1 (char *p, tree outputs, tree inputs, tree labels) 614 { 615 char *q; 616 int op; 617 tree t; 618 619 /* Collect the operand name. */ 620 q = strchr (++p, ']'); 621 if (!q) 622 { 623 error ("missing close brace for named operand"); 624 return strchr (p, '\0'); 625 } 626 *q = '\0'; 627 628 /* Resolve the name to a number. */ 629 for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++) 630 { 631 tree name = TREE_PURPOSE (TREE_PURPOSE (t)); 632 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0) 633 goto found; 634 } 635 for (t = inputs; t ; t = TREE_CHAIN (t), op++) 636 { 637 tree name = TREE_PURPOSE (TREE_PURPOSE (t)); 638 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0) 639 goto found; 640 } 641 for (t = labels; t ; t = TREE_CHAIN (t), op++) 642 { 643 tree name = TREE_PURPOSE (t); 644 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0) 645 goto found; 646 } 647 648 error ("undefined named operand %qs", identifier_to_locale (p)); 649 op = 0; 650 651 found: 652 /* Replace the name with the number. Unfortunately, not all libraries 653 get the return value of sprintf correct, so search for the end of the 654 generated string by hand. */ 655 sprintf (--p, "%d", op); 656 p = strchr (p, '\0'); 657 658 /* Verify the no extra buffer space assumption. */ 659 gcc_assert (p <= q); 660 661 /* Shift the rest of the buffer down to fill the gap. */ 662 memmove (p, q + 1, strlen (q + 1) + 1); 663 664 return p; 665 } 666 667 668 /* Generate RTL to return directly from the current function. 669 (That is, we bypass any return value.) */ 670 671 void 672 expand_naked_return (void) 673 { 674 rtx_code_label *end_label; 675 676 clear_pending_stack_adjust (); 677 do_pending_stack_adjust (); 678 679 end_label = naked_return_label; 680 if (end_label == 0) 681 end_label = naked_return_label = gen_label_rtx (); 682 683 emit_jump (end_label); 684 } 685 686 /* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE. PROB 687 is the probability of jumping to LABEL. */ 688 static void 689 do_jump_if_equal (machine_mode mode, rtx op0, rtx op1, rtx_code_label *label, 690 int unsignedp, profile_probability prob) 691 { 692 do_compare_rtx_and_jump (op0, op1, EQ, unsignedp, mode, 693 NULL_RTX, NULL, label, prob); 694 } 695 696 /* Return the sum of probabilities of outgoing edges of basic block BB. */ 697 698 static profile_probability 699 get_outgoing_edge_probs (basic_block bb) 700 { 701 edge e; 702 edge_iterator ei; 703 profile_probability prob_sum = profile_probability::never (); 704 if (!bb) 705 return profile_probability::never (); 706 FOR_EACH_EDGE (e, ei, bb->succs) 707 prob_sum += e->probability; 708 return prob_sum; 709 } 710 711 /* Computes the conditional probability of jumping to a target if the branch 712 instruction is executed. 713 TARGET_PROB is the estimated probability of jumping to a target relative 714 to some basic block BB. 715 BASE_PROB is the probability of reaching the branch instruction relative 716 to the same basic block BB. */ 717 718 static inline profile_probability 719 conditional_probability (profile_probability target_prob, 720 profile_probability base_prob) 721 { 722 return target_prob / base_prob; 723 } 724 725 /* Generate a dispatch tabler, switching on INDEX_EXPR and jumping to 726 one of the labels in CASE_LIST or to the DEFAULT_LABEL. 727 MINVAL, MAXVAL, and RANGE are the extrema and range of the case 728 labels in CASE_LIST. STMT_BB is the basic block containing the statement. 729 730 First, a jump insn is emitted. First we try "casesi". If that 731 fails, try "tablejump". A target *must* have one of them (or both). 732 733 Then, a table with the target labels is emitted. 734 735 The process is unaware of the CFG. The caller has to fix up 736 the CFG itself. This is done in cfgexpand.c. */ 737 738 static void 739 emit_case_dispatch_table (tree index_expr, tree index_type, 740 auto_vec<simple_case_node> &case_list, 741 rtx default_label, 742 edge default_edge, tree minval, tree maxval, 743 tree range, basic_block stmt_bb) 744 { 745 int i, ncases; 746 rtx *labelvec; 747 rtx_insn *fallback_label = label_rtx (case_list[0].m_code_label); 748 rtx_code_label *table_label = gen_label_rtx (); 749 bool has_gaps = false; 750 profile_probability default_prob = default_edge ? default_edge->probability 751 : profile_probability::never (); 752 profile_probability base = get_outgoing_edge_probs (stmt_bb); 753 bool try_with_tablejump = false; 754 755 profile_probability new_default_prob = conditional_probability (default_prob, 756 base); 757 758 if (! try_casesi (index_type, index_expr, minval, range, 759 table_label, default_label, fallback_label, 760 new_default_prob)) 761 { 762 /* Index jumptables from zero for suitable values of minval to avoid 763 a subtraction. For the rationale see: 764 "http://gcc.gnu.org/ml/gcc-patches/2001-10/msg01234.html". */ 765 if (optimize_insn_for_speed_p () 766 && compare_tree_int (minval, 0) > 0 767 && compare_tree_int (minval, 3) < 0) 768 { 769 minval = build_int_cst (index_type, 0); 770 range = maxval; 771 has_gaps = true; 772 } 773 try_with_tablejump = true; 774 } 775 776 /* Get table of labels to jump to, in order of case index. */ 777 778 ncases = tree_to_shwi (range) + 1; 779 labelvec = XALLOCAVEC (rtx, ncases); 780 memset (labelvec, 0, ncases * sizeof (rtx)); 781 782 for (unsigned j = 0; j < case_list.length (); j++) 783 { 784 simple_case_node *n = &case_list[j]; 785 /* Compute the low and high bounds relative to the minimum 786 value since that should fit in a HOST_WIDE_INT while the 787 actual values may not. */ 788 HOST_WIDE_INT i_low 789 = tree_to_uhwi (fold_build2 (MINUS_EXPR, index_type, 790 n->m_low, minval)); 791 HOST_WIDE_INT i_high 792 = tree_to_uhwi (fold_build2 (MINUS_EXPR, index_type, 793 n->m_high, minval)); 794 HOST_WIDE_INT i; 795 796 for (i = i_low; i <= i_high; i ++) 797 labelvec[i] 798 = gen_rtx_LABEL_REF (Pmode, label_rtx (n->m_code_label)); 799 } 800 801 /* The dispatch table may contain gaps, including at the beginning of 802 the table if we tried to avoid the minval subtraction. We fill the 803 dispatch table slots associated with the gaps with the default case label. 804 However, in the event the default case is unreachable, we then use 805 any label from one of the case statements. */ 806 rtx gap_label = (default_label) ? default_label : fallback_label; 807 808 for (i = 0; i < ncases; i++) 809 if (labelvec[i] == 0) 810 { 811 has_gaps = true; 812 labelvec[i] = gen_rtx_LABEL_REF (Pmode, gap_label); 813 } 814 815 if (has_gaps && default_label) 816 { 817 /* There is at least one entry in the jump table that jumps 818 to default label. The default label can either be reached 819 through the indirect jump or the direct conditional jump 820 before that. Split the probability of reaching the 821 default label among these two jumps. */ 822 new_default_prob 823 = conditional_probability (default_prob.apply_scale (1, 2), base); 824 default_prob = default_prob.apply_scale (1, 2); 825 base -= default_prob; 826 } 827 else 828 { 829 base -= default_prob; 830 default_prob = profile_probability::never (); 831 } 832 833 if (default_edge) 834 default_edge->probability = default_prob; 835 836 /* We have altered the probability of the default edge. So the probabilities 837 of all other edges need to be adjusted so that it sums up to 838 REG_BR_PROB_BASE. */ 839 if (base > profile_probability::never ()) 840 { 841 edge e; 842 edge_iterator ei; 843 FOR_EACH_EDGE (e, ei, stmt_bb->succs) 844 e->probability /= base; 845 } 846 847 if (try_with_tablejump) 848 { 849 bool ok = try_tablejump (index_type, index_expr, minval, range, 850 table_label, default_label, new_default_prob); 851 gcc_assert (ok); 852 } 853 /* Output the table. */ 854 emit_label (table_label); 855 856 if (CASE_VECTOR_PC_RELATIVE || flag_pic) 857 emit_jump_table_data (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE, 858 gen_rtx_LABEL_REF (Pmode, 859 table_label), 860 gen_rtvec_v (ncases, labelvec), 861 const0_rtx, const0_rtx)); 862 else 863 emit_jump_table_data (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE, 864 gen_rtvec_v (ncases, labelvec))); 865 866 /* Record no drop-through after the table. */ 867 emit_barrier (); 868 } 869 870 /* Terminate a case Ada or switch (C) statement 871 in which ORIG_INDEX is the expression to be tested. 872 If ORIG_TYPE is not NULL, it is the original ORIG_INDEX 873 type as given in the source before any compiler conversions. 874 Generate the code to test it and jump to the right place. */ 875 876 void 877 expand_case (gswitch *stmt) 878 { 879 tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE; 880 rtx_code_label *default_label; 881 unsigned int count; 882 int i; 883 int ncases = gimple_switch_num_labels (stmt); 884 tree index_expr = gimple_switch_index (stmt); 885 tree index_type = TREE_TYPE (index_expr); 886 tree elt; 887 basic_block bb = gimple_bb (stmt); 888 889 auto_vec<simple_case_node> case_list; 890 891 /* An ERROR_MARK occurs for various reasons including invalid data type. 892 ??? Can this still happen, with GIMPLE and all? */ 893 if (index_type == error_mark_node) 894 return; 895 896 /* cleanup_tree_cfg removes all SWITCH_EXPR with their index 897 expressions being INTEGER_CST. */ 898 gcc_assert (TREE_CODE (index_expr) != INTEGER_CST); 899 900 /* Optimization of switch statements with only one label has already 901 occurred, so we should never see them at this point. */ 902 gcc_assert (ncases > 1); 903 904 do_pending_stack_adjust (); 905 906 /* Find the default case target label. */ 907 tree default_lab = CASE_LABEL (gimple_switch_default_label (stmt)); 908 default_label = jump_target_rtx (default_lab); 909 basic_block default_bb = label_to_block_fn (cfun, default_lab); 910 edge default_edge = find_edge (bb, default_bb); 911 912 /* Get upper and lower bounds of case values. */ 913 elt = gimple_switch_label (stmt, 1); 914 minval = fold_convert (index_type, CASE_LOW (elt)); 915 elt = gimple_switch_label (stmt, ncases - 1); 916 if (CASE_HIGH (elt)) 917 maxval = fold_convert (index_type, CASE_HIGH (elt)); 918 else 919 maxval = fold_convert (index_type, CASE_LOW (elt)); 920 921 /* Compute span of values. */ 922 range = fold_build2 (MINUS_EXPR, index_type, maxval, minval); 923 924 /* Listify the labels queue and gather some numbers to decide 925 how to expand this switch(). */ 926 count = 0; 927 928 for (i = ncases - 1; i >= 1; --i) 929 { 930 elt = gimple_switch_label (stmt, i); 931 tree low = CASE_LOW (elt); 932 gcc_assert (low); 933 tree high = CASE_HIGH (elt); 934 gcc_assert (! high || tree_int_cst_lt (low, high)); 935 tree lab = CASE_LABEL (elt); 936 937 /* Count the elements. 938 A range counts double, since it requires two compares. */ 939 count++; 940 if (high) 941 count++; 942 943 /* The bounds on the case range, LOW and HIGH, have to be converted 944 to case's index type TYPE. Note that the original type of the 945 case index in the source code is usually "lost" during 946 gimplification due to type promotion, but the case labels retain the 947 original type. Make sure to drop overflow flags. */ 948 low = fold_convert (index_type, low); 949 if (TREE_OVERFLOW (low)) 950 low = wide_int_to_tree (index_type, wi::to_wide (low)); 951 952 /* The canonical from of a case label in GIMPLE is that a simple case 953 has an empty CASE_HIGH. For the casesi and tablejump expanders, 954 the back ends want simple cases to have high == low. */ 955 if (! high) 956 high = low; 957 high = fold_convert (index_type, high); 958 if (TREE_OVERFLOW (high)) 959 high = wide_int_to_tree (index_type, wi::to_wide (high)); 960 961 case_list.safe_push (simple_case_node (low, high, lab)); 962 } 963 964 /* cleanup_tree_cfg removes all SWITCH_EXPR with a single 965 destination, such as one with a default case only. 966 It also removes cases that are out of range for the switch 967 type, so we should never get a zero here. */ 968 gcc_assert (count > 0); 969 970 rtx_insn *before_case = get_last_insn (); 971 972 /* Decide how to expand this switch. 973 The two options at this point are a dispatch table (casesi or 974 tablejump) or a decision tree. */ 975 976 { 977 /* If the default case is unreachable, then set default_label to NULL 978 so that we omit the range check when generating the dispatch table. 979 We also remove the edge to the unreachable default case. The block 980 itself will be automatically removed later. */ 981 if (EDGE_COUNT (default_edge->dest->succs) == 0 982 && gimple_seq_unreachable_p (bb_seq (default_edge->dest))) 983 { 984 default_label = NULL; 985 remove_edge (default_edge); 986 default_edge = NULL; 987 } 988 emit_case_dispatch_table (index_expr, index_type, 989 case_list, default_label, default_edge, 990 minval, maxval, range, bb); 991 } 992 993 reorder_insns (NEXT_INSN (before_case), get_last_insn (), before_case); 994 995 free_temp_slots (); 996 } 997 998 /* Expand the dispatch to a short decrement chain if there are few cases 999 to dispatch to. Likewise if neither casesi nor tablejump is available, 1000 or if flag_jump_tables is set. Otherwise, expand as a casesi or a 1001 tablejump. The index mode is always the mode of integer_type_node. 1002 Trap if no case matches the index. 1003 1004 DISPATCH_INDEX is the index expression to switch on. It should be a 1005 memory or register operand. 1006 1007 DISPATCH_TABLE is a set of case labels. The set should be sorted in 1008 ascending order, be contiguous, starting with value 0, and contain only 1009 single-valued case labels. */ 1010 1011 void 1012 expand_sjlj_dispatch_table (rtx dispatch_index, 1013 vec<tree> dispatch_table) 1014 { 1015 tree index_type = integer_type_node; 1016 machine_mode index_mode = TYPE_MODE (index_type); 1017 1018 int ncases = dispatch_table.length (); 1019 1020 do_pending_stack_adjust (); 1021 rtx_insn *before_case = get_last_insn (); 1022 1023 /* Expand as a decrement-chain if there are 5 or fewer dispatch 1024 labels. This covers more than 98% of the cases in libjava, 1025 and seems to be a reasonable compromise between the "old way" 1026 of expanding as a decision tree or dispatch table vs. the "new 1027 way" with decrement chain or dispatch table. */ 1028 if (dispatch_table.length () <= 5 1029 || (!targetm.have_casesi () && !targetm.have_tablejump ()) 1030 || !flag_jump_tables) 1031 { 1032 /* Expand the dispatch as a decrement chain: 1033 1034 "switch(index) {case 0: do_0; case 1: do_1; ...; case N: do_N;}" 1035 1036 ==> 1037 1038 if (index == 0) do_0; else index--; 1039 if (index == 0) do_1; else index--; 1040 ... 1041 if (index == 0) do_N; else index--; 1042 1043 This is more efficient than a dispatch table on most machines. 1044 The last "index--" is redundant but the code is trivially dead 1045 and will be cleaned up by later passes. */ 1046 rtx index = copy_to_mode_reg (index_mode, dispatch_index); 1047 rtx zero = CONST0_RTX (index_mode); 1048 for (int i = 0; i < ncases; i++) 1049 { 1050 tree elt = dispatch_table[i]; 1051 rtx_code_label *lab = jump_target_rtx (CASE_LABEL (elt)); 1052 do_jump_if_equal (index_mode, index, zero, lab, 0, 1053 profile_probability::uninitialized ()); 1054 force_expand_binop (index_mode, sub_optab, 1055 index, CONST1_RTX (index_mode), 1056 index, 0, OPTAB_DIRECT); 1057 } 1058 } 1059 else 1060 { 1061 /* Similar to expand_case, but much simpler. */ 1062 auto_vec<simple_case_node> case_list; 1063 tree index_expr = make_tree (index_type, dispatch_index); 1064 tree minval = build_int_cst (index_type, 0); 1065 tree maxval = CASE_LOW (dispatch_table.last ()); 1066 tree range = maxval; 1067 rtx_code_label *default_label = gen_label_rtx (); 1068 1069 for (int i = ncases - 1; i >= 0; --i) 1070 { 1071 tree elt = dispatch_table[i]; 1072 tree high = CASE_HIGH (elt); 1073 if (high == NULL_TREE) 1074 high = CASE_LOW (elt); 1075 case_list.safe_push (simple_case_node (CASE_LOW (elt), high, 1076 CASE_LABEL (elt))); 1077 } 1078 1079 emit_case_dispatch_table (index_expr, index_type, 1080 case_list, default_label, NULL, 1081 minval, maxval, range, 1082 BLOCK_FOR_INSN (before_case)); 1083 emit_label (default_label); 1084 } 1085 1086 /* Dispatching something not handled? Trap! */ 1087 expand_builtin_trap (); 1088 1089 reorder_insns (NEXT_INSN (before_case), get_last_insn (), before_case); 1090 1091 free_temp_slots (); 1092 } 1093 1094 1095