1 /* Expands front end tree to back end RTL for GCC 2 Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 3 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 4 2010, 2011, 2012 Free Software Foundation, Inc. 5 6 This file is part of GCC. 7 8 GCC is free software; you can redistribute it and/or modify it under 9 the terms of the GNU General Public License as published by the Free 10 Software Foundation; either version 3, or (at your option) any later 11 version. 12 13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY 14 WARRANTY; without even the implied warranty of MERCHANTABILITY or 15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 16 for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with GCC; see the file COPYING3. If not see 20 <http://www.gnu.org/licenses/>. */ 21 22 /* This file handles the generation of rtl code from tree structure 23 above the level of expressions, using subroutines in exp*.c and emit-rtl.c. 24 The functions whose names start with `expand_' are called by the 25 expander to generate RTL instructions for various kinds of constructs. */ 26 27 #include "config.h" 28 #include "system.h" 29 #include "coretypes.h" 30 #include "tm.h" 31 32 #include "rtl.h" 33 #include "hard-reg-set.h" 34 #include "tree.h" 35 #include "tm_p.h" 36 #include "flags.h" 37 #include "except.h" 38 #include "function.h" 39 #include "insn-config.h" 40 #include "expr.h" 41 #include "libfuncs.h" 42 #include "recog.h" 43 #include "machmode.h" 44 #include "diagnostic-core.h" 45 #include "output.h" 46 #include "ggc.h" 47 #include "langhooks.h" 48 #include "predict.h" 49 #include "optabs.h" 50 #include "target.h" 51 #include "gimple.h" 52 #include "regs.h" 53 #include "alloc-pool.h" 54 #include "pretty-print.h" 55 #include "bitmap.h" 56 #include "params.h" 57 58 59 /* Functions and data structures for expanding case statements. */ 60 61 /* Case label structure, used to hold info on labels within case 62 statements. We handle "range" labels; for a single-value label 63 as in C, the high and low limits are the same. 64 65 We start with a vector of case nodes sorted in ascending order, and 66 the default label as the last element in the vector. Before expanding 67 to RTL, we transform this vector into a list linked via the RIGHT 68 fields in the case_node struct. Nodes with higher case values are 69 later in the list. 70 71 Switch statements can be output in three forms. A branch table is 72 used if there are more than a few labels and the labels are dense 73 within the range between the smallest and largest case value. If a 74 branch table is used, no further manipulations are done with the case 75 node chain. 76 77 The alternative to the use of a branch table is to generate a series 78 of compare and jump insns. When that is done, we use the LEFT, RIGHT, 79 and PARENT fields to hold a binary tree. Initially the tree is 80 totally unbalanced, with everything on the right. We balance the tree 81 with nodes on the left having lower case values than the parent 82 and nodes on the right having higher values. We then output the tree 83 in order. 84 85 For very small, suitable switch statements, we can generate a series 86 of simple bit test and branches instead. */ 87 88 struct case_node 89 { 90 struct case_node *left; /* Left son in binary tree */ 91 struct case_node *right; /* Right son in binary tree; also node chain */ 92 struct case_node *parent; /* Parent of node in binary tree */ 93 tree low; /* Lowest index value for this label */ 94 tree high; /* Highest index value for this label */ 95 tree code_label; /* Label to jump to when node matches */ 96 }; 97 98 typedef struct case_node case_node; 99 typedef struct case_node *case_node_ptr; 100 101 /* These are used by estimate_case_costs and balance_case_nodes. */ 102 103 /* This must be a signed type, and non-ANSI compilers lack signed char. */ 104 static short cost_table_[129]; 105 static int use_cost_table; 106 static int cost_table_initialized; 107 108 /* Special care is needed because we allow -1, but TREE_INT_CST_LOW 109 is unsigned. */ 110 #define COST_TABLE(I) cost_table_[(unsigned HOST_WIDE_INT) ((I) + 1)] 111 112 static int n_occurrences (int, const char *); 113 static bool tree_conflicts_with_clobbers_p (tree, HARD_REG_SET *); 114 static void expand_nl_goto_receiver (void); 115 static bool check_operand_nalternatives (tree, tree); 116 static bool check_unique_operand_names (tree, tree, tree); 117 static char *resolve_operand_name_1 (char *, tree, tree, tree); 118 static void expand_null_return_1 (void); 119 static void expand_value_return (rtx); 120 static int estimate_case_costs (case_node_ptr); 121 static bool lshift_cheap_p (void); 122 static int case_bit_test_cmp (const void *, const void *); 123 static void emit_case_bit_tests (tree, tree, tree, tree, case_node_ptr, rtx); 124 static void balance_case_nodes (case_node_ptr *, case_node_ptr); 125 static int node_has_low_bound (case_node_ptr, tree); 126 static int node_has_high_bound (case_node_ptr, tree); 127 static int node_is_bounded (case_node_ptr, tree); 128 static void emit_case_nodes (rtx, case_node_ptr, rtx, tree); 129 static struct case_node *add_case_node (struct case_node *, tree, 130 tree, tree, tree, alloc_pool); 131 132 133 /* Return the rtx-label that corresponds to a LABEL_DECL, 134 creating it if necessary. */ 135 136 rtx 137 label_rtx (tree label) 138 { 139 gcc_assert (TREE_CODE (label) == LABEL_DECL); 140 141 if (!DECL_RTL_SET_P (label)) 142 { 143 rtx r = gen_label_rtx (); 144 SET_DECL_RTL (label, r); 145 if (FORCED_LABEL (label) || DECL_NONLOCAL (label)) 146 LABEL_PRESERVE_P (r) = 1; 147 } 148 149 return DECL_RTL (label); 150 } 151 152 /* As above, but also put it on the forced-reference list of the 153 function that contains it. */ 154 rtx 155 force_label_rtx (tree label) 156 { 157 rtx ref = label_rtx (label); 158 tree function = decl_function_context (label); 159 160 gcc_assert (function); 161 162 forced_labels = gen_rtx_EXPR_LIST (VOIDmode, ref, forced_labels); 163 return ref; 164 } 165 166 /* Add an unconditional jump to LABEL as the next sequential instruction. */ 167 168 void 169 emit_jump (rtx label) 170 { 171 do_pending_stack_adjust (); 172 emit_jump_insn (gen_jump (label)); 173 emit_barrier (); 174 } 175 176 /* Emit code to jump to the address 177 specified by the pointer expression EXP. */ 178 179 void 180 expand_computed_goto (tree exp) 181 { 182 rtx x = expand_normal (exp); 183 184 x = convert_memory_address (Pmode, x); 185 186 do_pending_stack_adjust (); 187 emit_indirect_jump (x); 188 } 189 190 /* Handle goto statements and the labels that they can go to. */ 191 192 /* Specify the location in the RTL code of a label LABEL, 193 which is a LABEL_DECL tree node. 194 195 This is used for the kind of label that the user can jump to with a 196 goto statement, and for alternatives of a switch or case statement. 197 RTL labels generated for loops and conditionals don't go through here; 198 they are generated directly at the RTL level, by other functions below. 199 200 Note that this has nothing to do with defining label *names*. 201 Languages vary in how they do that and what that even means. */ 202 203 void 204 expand_label (tree label) 205 { 206 rtx label_r = label_rtx (label); 207 208 do_pending_stack_adjust (); 209 emit_label (label_r); 210 if (DECL_NAME (label)) 211 LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label)); 212 213 if (DECL_NONLOCAL (label)) 214 { 215 expand_nl_goto_receiver (); 216 nonlocal_goto_handler_labels 217 = gen_rtx_EXPR_LIST (VOIDmode, label_r, 218 nonlocal_goto_handler_labels); 219 } 220 221 if (FORCED_LABEL (label)) 222 forced_labels = gen_rtx_EXPR_LIST (VOIDmode, label_r, forced_labels); 223 224 if (DECL_NONLOCAL (label) || FORCED_LABEL (label)) 225 maybe_set_first_label_num (label_r); 226 } 227 228 /* Generate RTL code for a `goto' statement with target label LABEL. 229 LABEL should be a LABEL_DECL tree node that was or will later be 230 defined with `expand_label'. */ 231 232 void 233 expand_goto (tree label) 234 { 235 #ifdef ENABLE_CHECKING 236 /* Check for a nonlocal goto to a containing function. Should have 237 gotten translated to __builtin_nonlocal_goto. */ 238 tree context = decl_function_context (label); 239 gcc_assert (!context || context == current_function_decl); 240 #endif 241 242 emit_jump (label_rtx (label)); 243 } 244 245 /* Return the number of times character C occurs in string S. */ 246 static int 247 n_occurrences (int c, const char *s) 248 { 249 int n = 0; 250 while (*s) 251 n += (*s++ == c); 252 return n; 253 } 254 255 /* Generate RTL for an asm statement (explicit assembler code). 256 STRING is a STRING_CST node containing the assembler code text, 257 or an ADDR_EXPR containing a STRING_CST. VOL nonzero means the 258 insn is volatile; don't optimize it. */ 259 260 static void 261 expand_asm_loc (tree string, int vol, location_t locus) 262 { 263 rtx body; 264 265 if (TREE_CODE (string) == ADDR_EXPR) 266 string = TREE_OPERAND (string, 0); 267 268 body = gen_rtx_ASM_INPUT_loc (VOIDmode, 269 ggc_strdup (TREE_STRING_POINTER (string)), 270 locus); 271 272 MEM_VOLATILE_P (body) = vol; 273 274 emit_insn (body); 275 } 276 277 /* Parse the output constraint pointed to by *CONSTRAINT_P. It is the 278 OPERAND_NUMth output operand, indexed from zero. There are NINPUTS 279 inputs and NOUTPUTS outputs to this extended-asm. Upon return, 280 *ALLOWS_MEM will be TRUE iff the constraint allows the use of a 281 memory operand. Similarly, *ALLOWS_REG will be TRUE iff the 282 constraint allows the use of a register operand. And, *IS_INOUT 283 will be true if the operand is read-write, i.e., if it is used as 284 an input as well as an output. If *CONSTRAINT_P is not in 285 canonical form, it will be made canonical. (Note that `+' will be 286 replaced with `=' as part of this process.) 287 288 Returns TRUE if all went well; FALSE if an error occurred. */ 289 290 bool 291 parse_output_constraint (const char **constraint_p, int operand_num, 292 int ninputs, int noutputs, bool *allows_mem, 293 bool *allows_reg, bool *is_inout) 294 { 295 const char *constraint = *constraint_p; 296 const char *p; 297 298 /* Assume the constraint doesn't allow the use of either a register 299 or memory. */ 300 *allows_mem = false; 301 *allows_reg = false; 302 303 /* Allow the `=' or `+' to not be at the beginning of the string, 304 since it wasn't explicitly documented that way, and there is a 305 large body of code that puts it last. Swap the character to 306 the front, so as not to uglify any place else. */ 307 p = strchr (constraint, '='); 308 if (!p) 309 p = strchr (constraint, '+'); 310 311 /* If the string doesn't contain an `=', issue an error 312 message. */ 313 if (!p) 314 { 315 error ("output operand constraint lacks %<=%>"); 316 return false; 317 } 318 319 /* If the constraint begins with `+', then the operand is both read 320 from and written to. */ 321 *is_inout = (*p == '+'); 322 323 /* Canonicalize the output constraint so that it begins with `='. */ 324 if (p != constraint || *is_inout) 325 { 326 char *buf; 327 size_t c_len = strlen (constraint); 328 329 if (p != constraint) 330 warning (0, "output constraint %qc for operand %d " 331 "is not at the beginning", 332 *p, operand_num); 333 334 /* Make a copy of the constraint. */ 335 buf = XALLOCAVEC (char, c_len + 1); 336 strcpy (buf, constraint); 337 /* Swap the first character and the `=' or `+'. */ 338 buf[p - constraint] = buf[0]; 339 /* Make sure the first character is an `='. (Until we do this, 340 it might be a `+'.) */ 341 buf[0] = '='; 342 /* Replace the constraint with the canonicalized string. */ 343 *constraint_p = ggc_alloc_string (buf, c_len); 344 constraint = *constraint_p; 345 } 346 347 /* Loop through the constraint string. */ 348 for (p = constraint + 1; *p; p += CONSTRAINT_LEN (*p, p)) 349 switch (*p) 350 { 351 case '+': 352 case '=': 353 error ("operand constraint contains incorrectly positioned " 354 "%<+%> or %<=%>"); 355 return false; 356 357 case '%': 358 if (operand_num + 1 == ninputs + noutputs) 359 { 360 error ("%<%%%> constraint used with last operand"); 361 return false; 362 } 363 break; 364 365 case 'V': case TARGET_MEM_CONSTRAINT: case 'o': 366 *allows_mem = true; 367 break; 368 369 case '?': case '!': case '*': case '&': case '#': 370 case 'E': case 'F': case 'G': case 'H': 371 case 's': case 'i': case 'n': 372 case 'I': case 'J': case 'K': case 'L': case 'M': 373 case 'N': case 'O': case 'P': case ',': 374 break; 375 376 case '0': case '1': case '2': case '3': case '4': 377 case '5': case '6': case '7': case '8': case '9': 378 case '[': 379 error ("matching constraint not valid in output operand"); 380 return false; 381 382 case '<': case '>': 383 /* ??? Before flow, auto inc/dec insns are not supposed to exist, 384 excepting those that expand_call created. So match memory 385 and hope. */ 386 *allows_mem = true; 387 break; 388 389 case 'g': case 'X': 390 *allows_reg = true; 391 *allows_mem = true; 392 break; 393 394 case 'p': case 'r': 395 *allows_reg = true; 396 break; 397 398 default: 399 if (!ISALPHA (*p)) 400 break; 401 if (REG_CLASS_FROM_CONSTRAINT (*p, p) != NO_REGS) 402 *allows_reg = true; 403 #ifdef EXTRA_CONSTRAINT_STR 404 else if (EXTRA_ADDRESS_CONSTRAINT (*p, p)) 405 *allows_reg = true; 406 else if (EXTRA_MEMORY_CONSTRAINT (*p, p)) 407 *allows_mem = true; 408 else 409 { 410 /* Otherwise we can't assume anything about the nature of 411 the constraint except that it isn't purely registers. 412 Treat it like "g" and hope for the best. */ 413 *allows_reg = true; 414 *allows_mem = true; 415 } 416 #endif 417 break; 418 } 419 420 return true; 421 } 422 423 /* Similar, but for input constraints. */ 424 425 bool 426 parse_input_constraint (const char **constraint_p, int input_num, 427 int ninputs, int noutputs, int ninout, 428 const char * const * constraints, 429 bool *allows_mem, bool *allows_reg) 430 { 431 const char *constraint = *constraint_p; 432 const char *orig_constraint = constraint; 433 size_t c_len = strlen (constraint); 434 size_t j; 435 bool saw_match = false; 436 437 /* Assume the constraint doesn't allow the use of either 438 a register or memory. */ 439 *allows_mem = false; 440 *allows_reg = false; 441 442 /* Make sure constraint has neither `=', `+', nor '&'. */ 443 444 for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j)) 445 switch (constraint[j]) 446 { 447 case '+': case '=': case '&': 448 if (constraint == orig_constraint) 449 { 450 error ("input operand constraint contains %qc", constraint[j]); 451 return false; 452 } 453 break; 454 455 case '%': 456 if (constraint == orig_constraint 457 && input_num + 1 == ninputs - ninout) 458 { 459 error ("%<%%%> constraint used with last operand"); 460 return false; 461 } 462 break; 463 464 case 'V': case TARGET_MEM_CONSTRAINT: case 'o': 465 *allows_mem = true; 466 break; 467 468 case '<': case '>': 469 case '?': case '!': case '*': case '#': 470 case 'E': case 'F': case 'G': case 'H': 471 case 's': case 'i': case 'n': 472 case 'I': case 'J': case 'K': case 'L': case 'M': 473 case 'N': case 'O': case 'P': case ',': 474 break; 475 476 /* Whether or not a numeric constraint allows a register is 477 decided by the matching constraint, and so there is no need 478 to do anything special with them. We must handle them in 479 the default case, so that we don't unnecessarily force 480 operands to memory. */ 481 case '0': case '1': case '2': case '3': case '4': 482 case '5': case '6': case '7': case '8': case '9': 483 { 484 char *end; 485 unsigned long match; 486 487 saw_match = true; 488 489 match = strtoul (constraint + j, &end, 10); 490 if (match >= (unsigned long) noutputs) 491 { 492 error ("matching constraint references invalid operand number"); 493 return false; 494 } 495 496 /* Try and find the real constraint for this dup. Only do this 497 if the matching constraint is the only alternative. */ 498 if (*end == '\0' 499 && (j == 0 || (j == 1 && constraint[0] == '%'))) 500 { 501 constraint = constraints[match]; 502 *constraint_p = constraint; 503 c_len = strlen (constraint); 504 j = 0; 505 /* ??? At the end of the loop, we will skip the first part of 506 the matched constraint. This assumes not only that the 507 other constraint is an output constraint, but also that 508 the '=' or '+' come first. */ 509 break; 510 } 511 else 512 j = end - constraint; 513 /* Anticipate increment at end of loop. */ 514 j--; 515 } 516 /* Fall through. */ 517 518 case 'p': case 'r': 519 *allows_reg = true; 520 break; 521 522 case 'g': case 'X': 523 *allows_reg = true; 524 *allows_mem = true; 525 break; 526 527 default: 528 if (! ISALPHA (constraint[j])) 529 { 530 error ("invalid punctuation %qc in constraint", constraint[j]); 531 return false; 532 } 533 if (REG_CLASS_FROM_CONSTRAINT (constraint[j], constraint + j) 534 != NO_REGS) 535 *allows_reg = true; 536 #ifdef EXTRA_CONSTRAINT_STR 537 else if (EXTRA_ADDRESS_CONSTRAINT (constraint[j], constraint + j)) 538 *allows_reg = true; 539 else if (EXTRA_MEMORY_CONSTRAINT (constraint[j], constraint + j)) 540 *allows_mem = true; 541 else 542 { 543 /* Otherwise we can't assume anything about the nature of 544 the constraint except that it isn't purely registers. 545 Treat it like "g" and hope for the best. */ 546 *allows_reg = true; 547 *allows_mem = true; 548 } 549 #endif 550 break; 551 } 552 553 if (saw_match && !*allows_reg) 554 warning (0, "matching constraint does not allow a register"); 555 556 return true; 557 } 558 559 /* Return DECL iff there's an overlap between *REGS and DECL, where DECL 560 can be an asm-declared register. Called via walk_tree. */ 561 562 static tree 563 decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED, 564 void *data) 565 { 566 tree decl = *declp; 567 const HARD_REG_SET *const regs = (const HARD_REG_SET *) data; 568 569 if (TREE_CODE (decl) == VAR_DECL) 570 { 571 if (DECL_HARD_REGISTER (decl) 572 && REG_P (DECL_RTL (decl)) 573 && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER) 574 { 575 rtx reg = DECL_RTL (decl); 576 577 if (overlaps_hard_reg_set_p (*regs, GET_MODE (reg), REGNO (reg))) 578 return decl; 579 } 580 walk_subtrees = 0; 581 } 582 else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL) 583 walk_subtrees = 0; 584 return NULL_TREE; 585 } 586 587 /* If there is an overlap between *REGS and DECL, return the first overlap 588 found. */ 589 tree 590 tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs) 591 { 592 return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL); 593 } 594 595 /* Check for overlap between registers marked in CLOBBERED_REGS and 596 anything inappropriate in T. Emit error and return the register 597 variable definition for error, NULL_TREE for ok. */ 598 599 static bool 600 tree_conflicts_with_clobbers_p (tree t, HARD_REG_SET *clobbered_regs) 601 { 602 /* Conflicts between asm-declared register variables and the clobber 603 list are not allowed. */ 604 tree overlap = tree_overlaps_hard_reg_set (t, clobbered_regs); 605 606 if (overlap) 607 { 608 error ("asm-specifier for variable %qE conflicts with asm clobber list", 609 DECL_NAME (overlap)); 610 611 /* Reset registerness to stop multiple errors emitted for a single 612 variable. */ 613 DECL_REGISTER (overlap) = 0; 614 return true; 615 } 616 617 return false; 618 } 619 620 /* Generate RTL for an asm statement with arguments. 621 STRING is the instruction template. 622 OUTPUTS is a list of output arguments (lvalues); INPUTS a list of inputs. 623 Each output or input has an expression in the TREE_VALUE and 624 a tree list in TREE_PURPOSE which in turn contains a constraint 625 name in TREE_VALUE (or NULL_TREE) and a constraint string 626 in TREE_PURPOSE. 627 CLOBBERS is a list of STRING_CST nodes each naming a hard register 628 that is clobbered by this insn. 629 630 Not all kinds of lvalue that may appear in OUTPUTS can be stored directly. 631 Some elements of OUTPUTS may be replaced with trees representing temporary 632 values. The caller should copy those temporary values to the originally 633 specified lvalues. 634 635 VOL nonzero means the insn is volatile; don't optimize it. */ 636 637 static void 638 expand_asm_operands (tree string, tree outputs, tree inputs, 639 tree clobbers, tree labels, int vol, location_t locus) 640 { 641 rtvec argvec, constraintvec, labelvec; 642 rtx body; 643 int ninputs = list_length (inputs); 644 int noutputs = list_length (outputs); 645 int nlabels = list_length (labels); 646 int ninout; 647 int nclobbers; 648 HARD_REG_SET clobbered_regs; 649 int clobber_conflict_found = 0; 650 tree tail; 651 tree t; 652 int i; 653 /* Vector of RTX's of evaluated output operands. */ 654 rtx *output_rtx = XALLOCAVEC (rtx, noutputs); 655 int *inout_opnum = XALLOCAVEC (int, noutputs); 656 rtx *real_output_rtx = XALLOCAVEC (rtx, noutputs); 657 enum machine_mode *inout_mode = XALLOCAVEC (enum machine_mode, noutputs); 658 const char **constraints = XALLOCAVEC (const char *, noutputs + ninputs); 659 int old_generating_concat_p = generating_concat_p; 660 661 /* An ASM with no outputs needs to be treated as volatile, for now. */ 662 if (noutputs == 0) 663 vol = 1; 664 665 if (! check_operand_nalternatives (outputs, inputs)) 666 return; 667 668 string = resolve_asm_operand_names (string, outputs, inputs, labels); 669 670 /* Collect constraints. */ 671 i = 0; 672 for (t = outputs; t ; t = TREE_CHAIN (t), i++) 673 constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t))); 674 for (t = inputs; t ; t = TREE_CHAIN (t), i++) 675 constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t))); 676 677 /* Sometimes we wish to automatically clobber registers across an asm. 678 Case in point is when the i386 backend moved from cc0 to a hard reg -- 679 maintaining source-level compatibility means automatically clobbering 680 the flags register. */ 681 clobbers = targetm.md_asm_clobbers (outputs, inputs, clobbers); 682 683 /* Count the number of meaningful clobbered registers, ignoring what 684 we would ignore later. */ 685 nclobbers = 0; 686 CLEAR_HARD_REG_SET (clobbered_regs); 687 for (tail = clobbers; tail; tail = TREE_CHAIN (tail)) 688 { 689 const char *regname; 690 int nregs; 691 692 if (TREE_VALUE (tail) == error_mark_node) 693 return; 694 regname = TREE_STRING_POINTER (TREE_VALUE (tail)); 695 696 i = decode_reg_name_and_count (regname, &nregs); 697 if (i == -4) 698 ++nclobbers; 699 else if (i == -2) 700 error ("unknown register name %qs in %<asm%>", regname); 701 702 /* Mark clobbered registers. */ 703 if (i >= 0) 704 { 705 int reg; 706 707 for (reg = i; reg < i + nregs; reg++) 708 { 709 ++nclobbers; 710 711 /* Clobbering the PIC register is an error. */ 712 if (reg == (int) PIC_OFFSET_TABLE_REGNUM) 713 { 714 error ("PIC register clobbered by %qs in %<asm%>", regname); 715 return; 716 } 717 718 SET_HARD_REG_BIT (clobbered_regs, reg); 719 } 720 } 721 } 722 723 /* First pass over inputs and outputs checks validity and sets 724 mark_addressable if needed. */ 725 726 ninout = 0; 727 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) 728 { 729 tree val = TREE_VALUE (tail); 730 tree type = TREE_TYPE (val); 731 const char *constraint; 732 bool is_inout; 733 bool allows_reg; 734 bool allows_mem; 735 736 /* If there's an erroneous arg, emit no insn. */ 737 if (type == error_mark_node) 738 return; 739 740 /* Try to parse the output constraint. If that fails, there's 741 no point in going further. */ 742 constraint = constraints[i]; 743 if (!parse_output_constraint (&constraint, i, ninputs, noutputs, 744 &allows_mem, &allows_reg, &is_inout)) 745 return; 746 747 if (! allows_reg 748 && (allows_mem 749 || is_inout 750 || (DECL_P (val) 751 && REG_P (DECL_RTL (val)) 752 && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type)))) 753 mark_addressable (val); 754 755 if (is_inout) 756 ninout++; 757 } 758 759 ninputs += ninout; 760 if (ninputs + noutputs > MAX_RECOG_OPERANDS) 761 { 762 error ("more than %d operands in %<asm%>", MAX_RECOG_OPERANDS); 763 return; 764 } 765 766 for (i = 0, tail = inputs; tail; i++, tail = TREE_CHAIN (tail)) 767 { 768 bool allows_reg, allows_mem; 769 const char *constraint; 770 771 /* If there's an erroneous arg, emit no insn, because the ASM_INPUT 772 would get VOIDmode and that could cause a crash in reload. */ 773 if (TREE_TYPE (TREE_VALUE (tail)) == error_mark_node) 774 return; 775 776 constraint = constraints[i + noutputs]; 777 if (! parse_input_constraint (&constraint, i, ninputs, noutputs, ninout, 778 constraints, &allows_mem, &allows_reg)) 779 return; 780 781 if (! allows_reg && allows_mem) 782 mark_addressable (TREE_VALUE (tail)); 783 } 784 785 /* Second pass evaluates arguments. */ 786 787 /* Make sure stack is consistent for asm goto. */ 788 if (nlabels > 0) 789 do_pending_stack_adjust (); 790 791 ninout = 0; 792 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) 793 { 794 tree val = TREE_VALUE (tail); 795 tree type = TREE_TYPE (val); 796 bool is_inout; 797 bool allows_reg; 798 bool allows_mem; 799 rtx op; 800 bool ok; 801 802 ok = parse_output_constraint (&constraints[i], i, ninputs, 803 noutputs, &allows_mem, &allows_reg, 804 &is_inout); 805 gcc_assert (ok); 806 807 /* If an output operand is not a decl or indirect ref and our constraint 808 allows a register, make a temporary to act as an intermediate. 809 Make the asm insn write into that, then our caller will copy it to 810 the real output operand. Likewise for promoted variables. */ 811 812 generating_concat_p = 0; 813 814 real_output_rtx[i] = NULL_RTX; 815 if ((TREE_CODE (val) == INDIRECT_REF 816 && allows_mem) 817 || (DECL_P (val) 818 && (allows_mem || REG_P (DECL_RTL (val))) 819 && ! (REG_P (DECL_RTL (val)) 820 && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type))) 821 || ! allows_reg 822 || is_inout) 823 { 824 op = expand_expr (val, NULL_RTX, VOIDmode, EXPAND_WRITE); 825 if (MEM_P (op)) 826 op = validize_mem (op); 827 828 if (! allows_reg && !MEM_P (op)) 829 error ("output number %d not directly addressable", i); 830 if ((! allows_mem && MEM_P (op)) 831 || GET_CODE (op) == CONCAT) 832 { 833 real_output_rtx[i] = op; 834 op = gen_reg_rtx (GET_MODE (op)); 835 if (is_inout) 836 emit_move_insn (op, real_output_rtx[i]); 837 } 838 } 839 else 840 { 841 op = assign_temp (type, 0, 0, 1); 842 op = validize_mem (op); 843 if (!MEM_P (op) && TREE_CODE (TREE_VALUE (tail)) == SSA_NAME) 844 set_reg_attrs_for_decl_rtl (SSA_NAME_VAR (TREE_VALUE (tail)), op); 845 TREE_VALUE (tail) = make_tree (type, op); 846 } 847 output_rtx[i] = op; 848 849 generating_concat_p = old_generating_concat_p; 850 851 if (is_inout) 852 { 853 inout_mode[ninout] = TYPE_MODE (type); 854 inout_opnum[ninout++] = i; 855 } 856 857 if (tree_conflicts_with_clobbers_p (val, &clobbered_regs)) 858 clobber_conflict_found = 1; 859 } 860 861 /* Make vectors for the expression-rtx, constraint strings, 862 and named operands. */ 863 864 argvec = rtvec_alloc (ninputs); 865 constraintvec = rtvec_alloc (ninputs); 866 labelvec = rtvec_alloc (nlabels); 867 868 body = gen_rtx_ASM_OPERANDS ((noutputs == 0 ? VOIDmode 869 : GET_MODE (output_rtx[0])), 870 ggc_strdup (TREE_STRING_POINTER (string)), 871 empty_string, 0, argvec, constraintvec, 872 labelvec, locus); 873 874 MEM_VOLATILE_P (body) = vol; 875 876 /* Eval the inputs and put them into ARGVEC. 877 Put their constraints into ASM_INPUTs and store in CONSTRAINTS. */ 878 879 for (i = 0, tail = inputs; tail; tail = TREE_CHAIN (tail), ++i) 880 { 881 bool allows_reg, allows_mem; 882 const char *constraint; 883 tree val, type; 884 rtx op; 885 bool ok; 886 887 constraint = constraints[i + noutputs]; 888 ok = parse_input_constraint (&constraint, i, ninputs, noutputs, ninout, 889 constraints, &allows_mem, &allows_reg); 890 gcc_assert (ok); 891 892 generating_concat_p = 0; 893 894 val = TREE_VALUE (tail); 895 type = TREE_TYPE (val); 896 /* EXPAND_INITIALIZER will not generate code for valid initializer 897 constants, but will still generate code for other types of operand. 898 This is the behavior we want for constant constraints. */ 899 op = expand_expr (val, NULL_RTX, VOIDmode, 900 allows_reg ? EXPAND_NORMAL 901 : allows_mem ? EXPAND_MEMORY 902 : EXPAND_INITIALIZER); 903 904 /* Never pass a CONCAT to an ASM. */ 905 if (GET_CODE (op) == CONCAT) 906 op = force_reg (GET_MODE (op), op); 907 else if (MEM_P (op)) 908 op = validize_mem (op); 909 910 if (asm_operand_ok (op, constraint, NULL) <= 0) 911 { 912 if (allows_reg && TYPE_MODE (type) != BLKmode) 913 op = force_reg (TYPE_MODE (type), op); 914 else if (!allows_mem) 915 warning (0, "asm operand %d probably doesn%'t match constraints", 916 i + noutputs); 917 else if (MEM_P (op)) 918 { 919 /* We won't recognize either volatile memory or memory 920 with a queued address as available a memory_operand 921 at this point. Ignore it: clearly this *is* a memory. */ 922 } 923 else 924 { 925 warning (0, "use of memory input without lvalue in " 926 "asm operand %d is deprecated", i + noutputs); 927 928 if (CONSTANT_P (op)) 929 { 930 rtx mem = force_const_mem (TYPE_MODE (type), op); 931 if (mem) 932 op = validize_mem (mem); 933 else 934 op = force_reg (TYPE_MODE (type), op); 935 } 936 if (REG_P (op) 937 || GET_CODE (op) == SUBREG 938 || GET_CODE (op) == CONCAT) 939 { 940 tree qual_type = build_qualified_type (type, 941 (TYPE_QUALS (type) 942 | TYPE_QUAL_CONST)); 943 rtx memloc = assign_temp (qual_type, 1, 1, 1); 944 memloc = validize_mem (memloc); 945 emit_move_insn (memloc, op); 946 op = memloc; 947 } 948 } 949 } 950 951 generating_concat_p = old_generating_concat_p; 952 ASM_OPERANDS_INPUT (body, i) = op; 953 954 ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, i) 955 = gen_rtx_ASM_INPUT (TYPE_MODE (type), 956 ggc_strdup (constraints[i + noutputs])); 957 958 if (tree_conflicts_with_clobbers_p (val, &clobbered_regs)) 959 clobber_conflict_found = 1; 960 } 961 962 /* Protect all the operands from the queue now that they have all been 963 evaluated. */ 964 965 generating_concat_p = 0; 966 967 /* For in-out operands, copy output rtx to input rtx. */ 968 for (i = 0; i < ninout; i++) 969 { 970 int j = inout_opnum[i]; 971 char buffer[16]; 972 973 ASM_OPERANDS_INPUT (body, ninputs - ninout + i) 974 = output_rtx[j]; 975 976 sprintf (buffer, "%d", j); 977 ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, ninputs - ninout + i) 978 = gen_rtx_ASM_INPUT (inout_mode[i], ggc_strdup (buffer)); 979 } 980 981 /* Copy labels to the vector. */ 982 for (i = 0, tail = labels; i < nlabels; ++i, tail = TREE_CHAIN (tail)) 983 ASM_OPERANDS_LABEL (body, i) 984 = gen_rtx_LABEL_REF (Pmode, label_rtx (TREE_VALUE (tail))); 985 986 generating_concat_p = old_generating_concat_p; 987 988 /* Now, for each output, construct an rtx 989 (set OUTPUT (asm_operands INSN OUTPUTCONSTRAINT OUTPUTNUMBER 990 ARGVEC CONSTRAINTS OPNAMES)) 991 If there is more than one, put them inside a PARALLEL. */ 992 993 if (nlabels > 0 && nclobbers == 0) 994 { 995 gcc_assert (noutputs == 0); 996 emit_jump_insn (body); 997 } 998 else if (noutputs == 0 && nclobbers == 0) 999 { 1000 /* No output operands: put in a raw ASM_OPERANDS rtx. */ 1001 emit_insn (body); 1002 } 1003 else if (noutputs == 1 && nclobbers == 0) 1004 { 1005 ASM_OPERANDS_OUTPUT_CONSTRAINT (body) = ggc_strdup (constraints[0]); 1006 emit_insn (gen_rtx_SET (VOIDmode, output_rtx[0], body)); 1007 } 1008 else 1009 { 1010 rtx obody = body; 1011 int num = noutputs; 1012 1013 if (num == 0) 1014 num = 1; 1015 1016 body = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (num + nclobbers)); 1017 1018 /* For each output operand, store a SET. */ 1019 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) 1020 { 1021 XVECEXP (body, 0, i) 1022 = gen_rtx_SET (VOIDmode, 1023 output_rtx[i], 1024 gen_rtx_ASM_OPERANDS 1025 (GET_MODE (output_rtx[i]), 1026 ggc_strdup (TREE_STRING_POINTER (string)), 1027 ggc_strdup (constraints[i]), 1028 i, argvec, constraintvec, labelvec, locus)); 1029 1030 MEM_VOLATILE_P (SET_SRC (XVECEXP (body, 0, i))) = vol; 1031 } 1032 1033 /* If there are no outputs (but there are some clobbers) 1034 store the bare ASM_OPERANDS into the PARALLEL. */ 1035 1036 if (i == 0) 1037 XVECEXP (body, 0, i++) = obody; 1038 1039 /* Store (clobber REG) for each clobbered register specified. */ 1040 1041 for (tail = clobbers; tail; tail = TREE_CHAIN (tail)) 1042 { 1043 const char *regname = TREE_STRING_POINTER (TREE_VALUE (tail)); 1044 int reg, nregs; 1045 int j = decode_reg_name_and_count (regname, &nregs); 1046 rtx clobbered_reg; 1047 1048 if (j < 0) 1049 { 1050 if (j == -3) /* `cc', which is not a register */ 1051 continue; 1052 1053 if (j == -4) /* `memory', don't cache memory across asm */ 1054 { 1055 XVECEXP (body, 0, i++) 1056 = gen_rtx_CLOBBER (VOIDmode, 1057 gen_rtx_MEM 1058 (BLKmode, 1059 gen_rtx_SCRATCH (VOIDmode))); 1060 continue; 1061 } 1062 1063 /* Ignore unknown register, error already signaled. */ 1064 continue; 1065 } 1066 1067 for (reg = j; reg < j + nregs; reg++) 1068 { 1069 /* Use QImode since that's guaranteed to clobber just 1070 * one reg. */ 1071 clobbered_reg = gen_rtx_REG (QImode, reg); 1072 1073 /* Do sanity check for overlap between clobbers and 1074 respectively input and outputs that hasn't been 1075 handled. Such overlap should have been detected and 1076 reported above. */ 1077 if (!clobber_conflict_found) 1078 { 1079 int opno; 1080 1081 /* We test the old body (obody) contents to avoid 1082 tripping over the under-construction body. */ 1083 for (opno = 0; opno < noutputs; opno++) 1084 if (reg_overlap_mentioned_p (clobbered_reg, 1085 output_rtx[opno])) 1086 internal_error 1087 ("asm clobber conflict with output operand"); 1088 1089 for (opno = 0; opno < ninputs - ninout; opno++) 1090 if (reg_overlap_mentioned_p (clobbered_reg, 1091 ASM_OPERANDS_INPUT (obody, 1092 opno))) 1093 internal_error 1094 ("asm clobber conflict with input operand"); 1095 } 1096 1097 XVECEXP (body, 0, i++) 1098 = gen_rtx_CLOBBER (VOIDmode, clobbered_reg); 1099 } 1100 } 1101 1102 if (nlabels > 0) 1103 emit_jump_insn (body); 1104 else 1105 emit_insn (body); 1106 } 1107 1108 /* For any outputs that needed reloading into registers, spill them 1109 back to where they belong. */ 1110 for (i = 0; i < noutputs; ++i) 1111 if (real_output_rtx[i]) 1112 emit_move_insn (real_output_rtx[i], output_rtx[i]); 1113 1114 crtl->has_asm_statement = 1; 1115 free_temp_slots (); 1116 } 1117 1118 void 1119 expand_asm_stmt (gimple stmt) 1120 { 1121 int noutputs; 1122 tree outputs, tail, t; 1123 tree *o; 1124 size_t i, n; 1125 const char *s; 1126 tree str, out, in, cl, labels; 1127 location_t locus = gimple_location (stmt); 1128 1129 /* Meh... convert the gimple asm operands into real tree lists. 1130 Eventually we should make all routines work on the vectors instead 1131 of relying on TREE_CHAIN. */ 1132 out = NULL_TREE; 1133 n = gimple_asm_noutputs (stmt); 1134 if (n > 0) 1135 { 1136 t = out = gimple_asm_output_op (stmt, 0); 1137 for (i = 1; i < n; i++) 1138 t = TREE_CHAIN (t) = gimple_asm_output_op (stmt, i); 1139 } 1140 1141 in = NULL_TREE; 1142 n = gimple_asm_ninputs (stmt); 1143 if (n > 0) 1144 { 1145 t = in = gimple_asm_input_op (stmt, 0); 1146 for (i = 1; i < n; i++) 1147 t = TREE_CHAIN (t) = gimple_asm_input_op (stmt, i); 1148 } 1149 1150 cl = NULL_TREE; 1151 n = gimple_asm_nclobbers (stmt); 1152 if (n > 0) 1153 { 1154 t = cl = gimple_asm_clobber_op (stmt, 0); 1155 for (i = 1; i < n; i++) 1156 t = TREE_CHAIN (t) = gimple_asm_clobber_op (stmt, i); 1157 } 1158 1159 labels = NULL_TREE; 1160 n = gimple_asm_nlabels (stmt); 1161 if (n > 0) 1162 { 1163 t = labels = gimple_asm_label_op (stmt, 0); 1164 for (i = 1; i < n; i++) 1165 t = TREE_CHAIN (t) = gimple_asm_label_op (stmt, i); 1166 } 1167 1168 s = gimple_asm_string (stmt); 1169 str = build_string (strlen (s), s); 1170 1171 if (gimple_asm_input_p (stmt)) 1172 { 1173 expand_asm_loc (str, gimple_asm_volatile_p (stmt), locus); 1174 return; 1175 } 1176 1177 outputs = out; 1178 noutputs = gimple_asm_noutputs (stmt); 1179 /* o[I] is the place that output number I should be written. */ 1180 o = (tree *) alloca (noutputs * sizeof (tree)); 1181 1182 /* Record the contents of OUTPUTS before it is modified. */ 1183 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) 1184 o[i] = TREE_VALUE (tail); 1185 1186 /* Generate the ASM_OPERANDS insn; store into the TREE_VALUEs of 1187 OUTPUTS some trees for where the values were actually stored. */ 1188 expand_asm_operands (str, outputs, in, cl, labels, 1189 gimple_asm_volatile_p (stmt), locus); 1190 1191 /* Copy all the intermediate outputs into the specified outputs. */ 1192 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++) 1193 { 1194 if (o[i] != TREE_VALUE (tail)) 1195 { 1196 expand_assignment (o[i], TREE_VALUE (tail), false); 1197 free_temp_slots (); 1198 1199 /* Restore the original value so that it's correct the next 1200 time we expand this function. */ 1201 TREE_VALUE (tail) = o[i]; 1202 } 1203 } 1204 } 1205 1206 /* A subroutine of expand_asm_operands. Check that all operands have 1207 the same number of alternatives. Return true if so. */ 1208 1209 static bool 1210 check_operand_nalternatives (tree outputs, tree inputs) 1211 { 1212 if (outputs || inputs) 1213 { 1214 tree tmp = TREE_PURPOSE (outputs ? outputs : inputs); 1215 int nalternatives 1216 = n_occurrences (',', TREE_STRING_POINTER (TREE_VALUE (tmp))); 1217 tree next = inputs; 1218 1219 if (nalternatives + 1 > MAX_RECOG_ALTERNATIVES) 1220 { 1221 error ("too many alternatives in %<asm%>"); 1222 return false; 1223 } 1224 1225 tmp = outputs; 1226 while (tmp) 1227 { 1228 const char *constraint 1229 = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tmp))); 1230 1231 if (n_occurrences (',', constraint) != nalternatives) 1232 { 1233 error ("operand constraints for %<asm%> differ " 1234 "in number of alternatives"); 1235 return false; 1236 } 1237 1238 if (TREE_CHAIN (tmp)) 1239 tmp = TREE_CHAIN (tmp); 1240 else 1241 tmp = next, next = 0; 1242 } 1243 } 1244 1245 return true; 1246 } 1247 1248 /* A subroutine of expand_asm_operands. Check that all operand names 1249 are unique. Return true if so. We rely on the fact that these names 1250 are identifiers, and so have been canonicalized by get_identifier, 1251 so all we need are pointer comparisons. */ 1252 1253 static bool 1254 check_unique_operand_names (tree outputs, tree inputs, tree labels) 1255 { 1256 tree i, j, i_name = NULL_TREE; 1257 1258 for (i = outputs; i ; i = TREE_CHAIN (i)) 1259 { 1260 i_name = TREE_PURPOSE (TREE_PURPOSE (i)); 1261 if (! i_name) 1262 continue; 1263 1264 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j)) 1265 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) 1266 goto failure; 1267 } 1268 1269 for (i = inputs; i ; i = TREE_CHAIN (i)) 1270 { 1271 i_name = TREE_PURPOSE (TREE_PURPOSE (i)); 1272 if (! i_name) 1273 continue; 1274 1275 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j)) 1276 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) 1277 goto failure; 1278 for (j = outputs; j ; j = TREE_CHAIN (j)) 1279 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) 1280 goto failure; 1281 } 1282 1283 for (i = labels; i ; i = TREE_CHAIN (i)) 1284 { 1285 i_name = TREE_PURPOSE (i); 1286 if (! i_name) 1287 continue; 1288 1289 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j)) 1290 if (simple_cst_equal (i_name, TREE_PURPOSE (j))) 1291 goto failure; 1292 for (j = inputs; j ; j = TREE_CHAIN (j)) 1293 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j)))) 1294 goto failure; 1295 } 1296 1297 return true; 1298 1299 failure: 1300 error ("duplicate asm operand name %qs", TREE_STRING_POINTER (i_name)); 1301 return false; 1302 } 1303 1304 /* A subroutine of expand_asm_operands. Resolve the names of the operands 1305 in *POUTPUTS and *PINPUTS to numbers, and replace the name expansions in 1306 STRING and in the constraints to those numbers. */ 1307 1308 tree 1309 resolve_asm_operand_names (tree string, tree outputs, tree inputs, tree labels) 1310 { 1311 char *buffer; 1312 char *p; 1313 const char *c; 1314 tree t; 1315 1316 check_unique_operand_names (outputs, inputs, labels); 1317 1318 /* Substitute [<name>] in input constraint strings. There should be no 1319 named operands in output constraints. */ 1320 for (t = inputs; t ; t = TREE_CHAIN (t)) 1321 { 1322 c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t))); 1323 if (strchr (c, '[') != NULL) 1324 { 1325 p = buffer = xstrdup (c); 1326 while ((p = strchr (p, '[')) != NULL) 1327 p = resolve_operand_name_1 (p, outputs, inputs, NULL); 1328 TREE_VALUE (TREE_PURPOSE (t)) 1329 = build_string (strlen (buffer), buffer); 1330 free (buffer); 1331 } 1332 } 1333 1334 /* Now check for any needed substitutions in the template. */ 1335 c = TREE_STRING_POINTER (string); 1336 while ((c = strchr (c, '%')) != NULL) 1337 { 1338 if (c[1] == '[') 1339 break; 1340 else if (ISALPHA (c[1]) && c[2] == '[') 1341 break; 1342 else 1343 { 1344 c += 1 + (c[1] == '%'); 1345 continue; 1346 } 1347 } 1348 1349 if (c) 1350 { 1351 /* OK, we need to make a copy so we can perform the substitutions. 1352 Assume that we will not need extra space--we get to remove '[' 1353 and ']', which means we cannot have a problem until we have more 1354 than 999 operands. */ 1355 buffer = xstrdup (TREE_STRING_POINTER (string)); 1356 p = buffer + (c - TREE_STRING_POINTER (string)); 1357 1358 while ((p = strchr (p, '%')) != NULL) 1359 { 1360 if (p[1] == '[') 1361 p += 1; 1362 else if (ISALPHA (p[1]) && p[2] == '[') 1363 p += 2; 1364 else 1365 { 1366 p += 1 + (p[1] == '%'); 1367 continue; 1368 } 1369 1370 p = resolve_operand_name_1 (p, outputs, inputs, labels); 1371 } 1372 1373 string = build_string (strlen (buffer), buffer); 1374 free (buffer); 1375 } 1376 1377 return string; 1378 } 1379 1380 /* A subroutine of resolve_operand_names. P points to the '[' for a 1381 potential named operand of the form [<name>]. In place, replace 1382 the name and brackets with a number. Return a pointer to the 1383 balance of the string after substitution. */ 1384 1385 static char * 1386 resolve_operand_name_1 (char *p, tree outputs, tree inputs, tree labels) 1387 { 1388 char *q; 1389 int op; 1390 tree t; 1391 1392 /* Collect the operand name. */ 1393 q = strchr (++p, ']'); 1394 if (!q) 1395 { 1396 error ("missing close brace for named operand"); 1397 return strchr (p, '\0'); 1398 } 1399 *q = '\0'; 1400 1401 /* Resolve the name to a number. */ 1402 for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++) 1403 { 1404 tree name = TREE_PURPOSE (TREE_PURPOSE (t)); 1405 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0) 1406 goto found; 1407 } 1408 for (t = inputs; t ; t = TREE_CHAIN (t), op++) 1409 { 1410 tree name = TREE_PURPOSE (TREE_PURPOSE (t)); 1411 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0) 1412 goto found; 1413 } 1414 for (t = labels; t ; t = TREE_CHAIN (t), op++) 1415 { 1416 tree name = TREE_PURPOSE (t); 1417 if (name && strcmp (TREE_STRING_POINTER (name), p) == 0) 1418 goto found; 1419 } 1420 1421 error ("undefined named operand %qs", identifier_to_locale (p)); 1422 op = 0; 1423 1424 found: 1425 /* Replace the name with the number. Unfortunately, not all libraries 1426 get the return value of sprintf correct, so search for the end of the 1427 generated string by hand. */ 1428 sprintf (--p, "%d", op); 1429 p = strchr (p, '\0'); 1430 1431 /* Verify the no extra buffer space assumption. */ 1432 gcc_assert (p <= q); 1433 1434 /* Shift the rest of the buffer down to fill the gap. */ 1435 memmove (p, q + 1, strlen (q + 1) + 1); 1436 1437 return p; 1438 } 1439 1440 /* Generate RTL to evaluate the expression EXP. */ 1441 1442 void 1443 expand_expr_stmt (tree exp) 1444 { 1445 rtx value; 1446 tree type; 1447 1448 value = expand_expr (exp, const0_rtx, VOIDmode, EXPAND_NORMAL); 1449 type = TREE_TYPE (exp); 1450 1451 /* If all we do is reference a volatile value in memory, 1452 copy it to a register to be sure it is actually touched. */ 1453 if (value && MEM_P (value) && TREE_THIS_VOLATILE (exp)) 1454 { 1455 if (TYPE_MODE (type) == VOIDmode) 1456 ; 1457 else if (TYPE_MODE (type) != BLKmode) 1458 copy_to_reg (value); 1459 else 1460 { 1461 rtx lab = gen_label_rtx (); 1462 1463 /* Compare the value with itself to reference it. */ 1464 emit_cmp_and_jump_insns (value, value, EQ, 1465 expand_normal (TYPE_SIZE (type)), 1466 BLKmode, 0, lab); 1467 emit_label (lab); 1468 } 1469 } 1470 1471 /* Free any temporaries used to evaluate this expression. */ 1472 free_temp_slots (); 1473 } 1474 1475 /* Warn if EXP contains any computations whose results are not used. 1476 Return 1 if a warning is printed; 0 otherwise. LOCUS is the 1477 (potential) location of the expression. */ 1478 1479 int 1480 warn_if_unused_value (const_tree exp, location_t locus) 1481 { 1482 restart: 1483 if (TREE_USED (exp) || TREE_NO_WARNING (exp)) 1484 return 0; 1485 1486 /* Don't warn about void constructs. This includes casting to void, 1487 void function calls, and statement expressions with a final cast 1488 to void. */ 1489 if (VOID_TYPE_P (TREE_TYPE (exp))) 1490 return 0; 1491 1492 if (EXPR_HAS_LOCATION (exp)) 1493 locus = EXPR_LOCATION (exp); 1494 1495 switch (TREE_CODE (exp)) 1496 { 1497 case PREINCREMENT_EXPR: 1498 case POSTINCREMENT_EXPR: 1499 case PREDECREMENT_EXPR: 1500 case POSTDECREMENT_EXPR: 1501 case MODIFY_EXPR: 1502 case INIT_EXPR: 1503 case TARGET_EXPR: 1504 case CALL_EXPR: 1505 case TRY_CATCH_EXPR: 1506 case WITH_CLEANUP_EXPR: 1507 case EXIT_EXPR: 1508 case VA_ARG_EXPR: 1509 return 0; 1510 1511 case BIND_EXPR: 1512 /* For a binding, warn if no side effect within it. */ 1513 exp = BIND_EXPR_BODY (exp); 1514 goto restart; 1515 1516 case SAVE_EXPR: 1517 case NON_LVALUE_EXPR: 1518 exp = TREE_OPERAND (exp, 0); 1519 goto restart; 1520 1521 case TRUTH_ORIF_EXPR: 1522 case TRUTH_ANDIF_EXPR: 1523 /* In && or ||, warn if 2nd operand has no side effect. */ 1524 exp = TREE_OPERAND (exp, 1); 1525 goto restart; 1526 1527 case COMPOUND_EXPR: 1528 if (warn_if_unused_value (TREE_OPERAND (exp, 0), locus)) 1529 return 1; 1530 /* Let people do `(foo (), 0)' without a warning. */ 1531 if (TREE_CONSTANT (TREE_OPERAND (exp, 1))) 1532 return 0; 1533 exp = TREE_OPERAND (exp, 1); 1534 goto restart; 1535 1536 case COND_EXPR: 1537 /* If this is an expression with side effects, don't warn; this 1538 case commonly appears in macro expansions. */ 1539 if (TREE_SIDE_EFFECTS (exp)) 1540 return 0; 1541 goto warn; 1542 1543 case INDIRECT_REF: 1544 /* Don't warn about automatic dereferencing of references, since 1545 the user cannot control it. */ 1546 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == REFERENCE_TYPE) 1547 { 1548 exp = TREE_OPERAND (exp, 0); 1549 goto restart; 1550 } 1551 /* Fall through. */ 1552 1553 default: 1554 /* Referencing a volatile value is a side effect, so don't warn. */ 1555 if ((DECL_P (exp) || REFERENCE_CLASS_P (exp)) 1556 && TREE_THIS_VOLATILE (exp)) 1557 return 0; 1558 1559 /* If this is an expression which has no operands, there is no value 1560 to be unused. There are no such language-independent codes, 1561 but front ends may define such. */ 1562 if (EXPRESSION_CLASS_P (exp) && TREE_OPERAND_LENGTH (exp) == 0) 1563 return 0; 1564 1565 warn: 1566 warning_at (locus, OPT_Wunused_value, "value computed is not used"); 1567 return 1; 1568 } 1569 } 1570 1571 1572 /* Generate RTL to return from the current function, with no value. 1573 (That is, we do not do anything about returning any value.) */ 1574 1575 void 1576 expand_null_return (void) 1577 { 1578 /* If this function was declared to return a value, but we 1579 didn't, clobber the return registers so that they are not 1580 propagated live to the rest of the function. */ 1581 clobber_return_register (); 1582 1583 expand_null_return_1 (); 1584 } 1585 1586 /* Generate RTL to return directly from the current function. 1587 (That is, we bypass any return value.) */ 1588 1589 void 1590 expand_naked_return (void) 1591 { 1592 rtx end_label; 1593 1594 clear_pending_stack_adjust (); 1595 do_pending_stack_adjust (); 1596 1597 end_label = naked_return_label; 1598 if (end_label == 0) 1599 end_label = naked_return_label = gen_label_rtx (); 1600 1601 emit_jump (end_label); 1602 } 1603 1604 /* Generate RTL to return from the current function, with value VAL. */ 1605 1606 static void 1607 expand_value_return (rtx val) 1608 { 1609 /* Copy the value to the return location unless it's already there. */ 1610 1611 tree decl = DECL_RESULT (current_function_decl); 1612 rtx return_reg = DECL_RTL (decl); 1613 if (return_reg != val) 1614 { 1615 tree funtype = TREE_TYPE (current_function_decl); 1616 tree type = TREE_TYPE (decl); 1617 int unsignedp = TYPE_UNSIGNED (type); 1618 enum machine_mode old_mode = DECL_MODE (decl); 1619 enum machine_mode mode; 1620 if (DECL_BY_REFERENCE (decl)) 1621 mode = promote_function_mode (type, old_mode, &unsignedp, funtype, 2); 1622 else 1623 mode = promote_function_mode (type, old_mode, &unsignedp, funtype, 1); 1624 1625 if (mode != old_mode) 1626 val = convert_modes (mode, old_mode, val, unsignedp); 1627 1628 if (GET_CODE (return_reg) == PARALLEL) 1629 emit_group_load (return_reg, val, type, int_size_in_bytes (type)); 1630 else 1631 emit_move_insn (return_reg, val); 1632 } 1633 1634 expand_null_return_1 (); 1635 } 1636 1637 /* Output a return with no value. */ 1638 1639 static void 1640 expand_null_return_1 (void) 1641 { 1642 clear_pending_stack_adjust (); 1643 do_pending_stack_adjust (); 1644 emit_jump (return_label); 1645 } 1646 1647 /* Generate RTL to evaluate the expression RETVAL and return it 1648 from the current function. */ 1649 1650 void 1651 expand_return (tree retval) 1652 { 1653 rtx result_rtl; 1654 rtx val = 0; 1655 tree retval_rhs; 1656 1657 /* If function wants no value, give it none. */ 1658 if (TREE_CODE (TREE_TYPE (TREE_TYPE (current_function_decl))) == VOID_TYPE) 1659 { 1660 expand_normal (retval); 1661 expand_null_return (); 1662 return; 1663 } 1664 1665 if (retval == error_mark_node) 1666 { 1667 /* Treat this like a return of no value from a function that 1668 returns a value. */ 1669 expand_null_return (); 1670 return; 1671 } 1672 else if ((TREE_CODE (retval) == MODIFY_EXPR 1673 || TREE_CODE (retval) == INIT_EXPR) 1674 && TREE_CODE (TREE_OPERAND (retval, 0)) == RESULT_DECL) 1675 retval_rhs = TREE_OPERAND (retval, 1); 1676 else 1677 retval_rhs = retval; 1678 1679 result_rtl = DECL_RTL (DECL_RESULT (current_function_decl)); 1680 1681 /* If we are returning the RESULT_DECL, then the value has already 1682 been stored into it, so we don't have to do anything special. */ 1683 if (TREE_CODE (retval_rhs) == RESULT_DECL) 1684 expand_value_return (result_rtl); 1685 1686 /* If the result is an aggregate that is being returned in one (or more) 1687 registers, load the registers here. */ 1688 1689 else if (retval_rhs != 0 1690 && TYPE_MODE (TREE_TYPE (retval_rhs)) == BLKmode 1691 && REG_P (result_rtl)) 1692 { 1693 val = copy_blkmode_to_reg (GET_MODE (result_rtl), retval_rhs); 1694 if (val) 1695 { 1696 /* Use the mode of the result value on the return register. */ 1697 PUT_MODE (result_rtl, GET_MODE (val)); 1698 expand_value_return (val); 1699 } 1700 else 1701 expand_null_return (); 1702 } 1703 else if (retval_rhs != 0 1704 && !VOID_TYPE_P (TREE_TYPE (retval_rhs)) 1705 && (REG_P (result_rtl) 1706 || (GET_CODE (result_rtl) == PARALLEL))) 1707 { 1708 /* Calculate the return value into a temporary (usually a pseudo 1709 reg). */ 1710 tree ot = TREE_TYPE (DECL_RESULT (current_function_decl)); 1711 tree nt = build_qualified_type (ot, TYPE_QUALS (ot) | TYPE_QUAL_CONST); 1712 1713 val = assign_temp (nt, 0, 0, 1); 1714 val = expand_expr (retval_rhs, val, GET_MODE (val), EXPAND_NORMAL); 1715 val = force_not_mem (val); 1716 /* Return the calculated value. */ 1717 expand_value_return (val); 1718 } 1719 else 1720 { 1721 /* No hard reg used; calculate value into hard return reg. */ 1722 expand_expr (retval, const0_rtx, VOIDmode, EXPAND_NORMAL); 1723 expand_value_return (result_rtl); 1724 } 1725 } 1726 1727 /* Emit code to restore vital registers at the beginning of a nonlocal goto 1728 handler. */ 1729 static void 1730 expand_nl_goto_receiver (void) 1731 { 1732 rtx chain; 1733 1734 /* Clobber the FP when we get here, so we have to make sure it's 1735 marked as used by this function. */ 1736 emit_use (hard_frame_pointer_rtx); 1737 1738 /* Mark the static chain as clobbered here so life information 1739 doesn't get messed up for it. */ 1740 chain = targetm.calls.static_chain (current_function_decl, true); 1741 if (chain && REG_P (chain)) 1742 emit_clobber (chain); 1743 1744 #ifdef HAVE_nonlocal_goto 1745 if (! HAVE_nonlocal_goto) 1746 #endif 1747 /* First adjust our frame pointer to its actual value. It was 1748 previously set to the start of the virtual area corresponding to 1749 the stacked variables when we branched here and now needs to be 1750 adjusted to the actual hardware fp value. 1751 1752 Assignments are to virtual registers are converted by 1753 instantiate_virtual_regs into the corresponding assignment 1754 to the underlying register (fp in this case) that makes 1755 the original assignment true. 1756 So the following insn will actually be 1757 decrementing fp by STARTING_FRAME_OFFSET. */ 1758 emit_move_insn (virtual_stack_vars_rtx, hard_frame_pointer_rtx); 1759 1760 #if !HARD_FRAME_POINTER_IS_ARG_POINTER 1761 if (fixed_regs[ARG_POINTER_REGNUM]) 1762 { 1763 #ifdef ELIMINABLE_REGS 1764 /* If the argument pointer can be eliminated in favor of the 1765 frame pointer, we don't need to restore it. We assume here 1766 that if such an elimination is present, it can always be used. 1767 This is the case on all known machines; if we don't make this 1768 assumption, we do unnecessary saving on many machines. */ 1769 static const struct elims {const int from, to;} elim_regs[] = ELIMINABLE_REGS; 1770 size_t i; 1771 1772 for (i = 0; i < ARRAY_SIZE (elim_regs); i++) 1773 if (elim_regs[i].from == ARG_POINTER_REGNUM 1774 && elim_regs[i].to == HARD_FRAME_POINTER_REGNUM) 1775 break; 1776 1777 if (i == ARRAY_SIZE (elim_regs)) 1778 #endif 1779 { 1780 /* Now restore our arg pointer from the address at which it 1781 was saved in our stack frame. */ 1782 emit_move_insn (crtl->args.internal_arg_pointer, 1783 copy_to_reg (get_arg_pointer_save_area ())); 1784 } 1785 } 1786 #endif 1787 1788 #ifdef HAVE_nonlocal_goto_receiver 1789 if (HAVE_nonlocal_goto_receiver) 1790 emit_insn (gen_nonlocal_goto_receiver ()); 1791 #endif 1792 1793 /* We must not allow the code we just generated to be reordered by 1794 scheduling. Specifically, the update of the frame pointer must 1795 happen immediately, not later. */ 1796 emit_insn (gen_blockage ()); 1797 } 1798 1799 /* Generate RTL for the automatic variable declaration DECL. 1800 (Other kinds of declarations are simply ignored if seen here.) */ 1801 1802 void 1803 expand_decl (tree decl) 1804 { 1805 tree type; 1806 1807 type = TREE_TYPE (decl); 1808 1809 /* For a CONST_DECL, set mode, alignment, and sizes from those of the 1810 type in case this node is used in a reference. */ 1811 if (TREE_CODE (decl) == CONST_DECL) 1812 { 1813 DECL_MODE (decl) = TYPE_MODE (type); 1814 DECL_ALIGN (decl) = TYPE_ALIGN (type); 1815 DECL_SIZE (decl) = TYPE_SIZE (type); 1816 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type); 1817 return; 1818 } 1819 1820 /* Otherwise, only automatic variables need any expansion done. Static and 1821 external variables, and external functions, will be handled by 1822 `assemble_variable' (called from finish_decl). TYPE_DECL requires 1823 nothing. PARM_DECLs are handled in `assign_parms'. */ 1824 if (TREE_CODE (decl) != VAR_DECL) 1825 return; 1826 1827 if (TREE_STATIC (decl) || DECL_EXTERNAL (decl)) 1828 return; 1829 1830 /* Create the RTL representation for the variable. */ 1831 1832 if (type == error_mark_node) 1833 SET_DECL_RTL (decl, gen_rtx_MEM (BLKmode, const0_rtx)); 1834 1835 else if (DECL_SIZE (decl) == 0) 1836 { 1837 /* Variable with incomplete type. */ 1838 rtx x; 1839 if (DECL_INITIAL (decl) == 0) 1840 /* Error message was already done; now avoid a crash. */ 1841 x = gen_rtx_MEM (BLKmode, const0_rtx); 1842 else 1843 /* An initializer is going to decide the size of this array. 1844 Until we know the size, represent its address with a reg. */ 1845 x = gen_rtx_MEM (BLKmode, gen_reg_rtx (Pmode)); 1846 1847 set_mem_attributes (x, decl, 1); 1848 SET_DECL_RTL (decl, x); 1849 } 1850 else if (use_register_for_decl (decl)) 1851 { 1852 /* Automatic variable that can go in a register. */ 1853 enum machine_mode reg_mode = promote_decl_mode (decl, NULL); 1854 1855 SET_DECL_RTL (decl, gen_reg_rtx (reg_mode)); 1856 1857 /* Note if the object is a user variable. */ 1858 if (!DECL_ARTIFICIAL (decl)) 1859 mark_user_reg (DECL_RTL (decl)); 1860 1861 if (POINTER_TYPE_P (type)) 1862 mark_reg_pointer (DECL_RTL (decl), 1863 TYPE_ALIGN (TREE_TYPE (TREE_TYPE (decl)))); 1864 } 1865 1866 else 1867 { 1868 rtx oldaddr = 0; 1869 rtx addr; 1870 rtx x; 1871 1872 /* Variable-sized decls are dealt with in the gimplifier. */ 1873 gcc_assert (TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST); 1874 1875 /* If we previously made RTL for this decl, it must be an array 1876 whose size was determined by the initializer. 1877 The old address was a register; set that register now 1878 to the proper address. */ 1879 if (DECL_RTL_SET_P (decl)) 1880 { 1881 gcc_assert (MEM_P (DECL_RTL (decl))); 1882 gcc_assert (REG_P (XEXP (DECL_RTL (decl), 0))); 1883 oldaddr = XEXP (DECL_RTL (decl), 0); 1884 } 1885 1886 /* Set alignment we actually gave this decl. */ 1887 DECL_ALIGN (decl) = (DECL_MODE (decl) == BLKmode ? BIGGEST_ALIGNMENT 1888 : GET_MODE_BITSIZE (DECL_MODE (decl))); 1889 DECL_USER_ALIGN (decl) = 0; 1890 1891 x = assign_temp (decl, 1, 1, 1); 1892 set_mem_attributes (x, decl, 1); 1893 SET_DECL_RTL (decl, x); 1894 1895 if (oldaddr) 1896 { 1897 addr = force_operand (XEXP (DECL_RTL (decl), 0), oldaddr); 1898 if (addr != oldaddr) 1899 emit_move_insn (oldaddr, addr); 1900 } 1901 } 1902 } 1903 1904 /* Emit code to save the current value of stack. */ 1905 rtx 1906 expand_stack_save (void) 1907 { 1908 rtx ret = NULL_RTX; 1909 1910 do_pending_stack_adjust (); 1911 emit_stack_save (SAVE_BLOCK, &ret); 1912 return ret; 1913 } 1914 1915 /* Emit code to restore the current value of stack. */ 1916 void 1917 expand_stack_restore (tree var) 1918 { 1919 rtx prev, sa = expand_normal (var); 1920 1921 sa = convert_memory_address (Pmode, sa); 1922 1923 prev = get_last_insn (); 1924 emit_stack_restore (SAVE_BLOCK, sa); 1925 fixup_args_size_notes (prev, get_last_insn (), 0); 1926 } 1927 1928 /* Do the insertion of a case label into case_list. The labels are 1929 fed to us in descending order from the sorted vector of case labels used 1930 in the tree part of the middle end. So the list we construct is 1931 sorted in ascending order. The bounds on the case range, LOW and HIGH, 1932 are converted to case's index type TYPE. */ 1933 1934 static struct case_node * 1935 add_case_node (struct case_node *head, tree type, tree low, tree high, 1936 tree label, alloc_pool case_node_pool) 1937 { 1938 tree min_value, max_value; 1939 struct case_node *r; 1940 1941 gcc_assert (TREE_CODE (low) == INTEGER_CST); 1942 gcc_assert (!high || TREE_CODE (high) == INTEGER_CST); 1943 1944 min_value = TYPE_MIN_VALUE (type); 1945 max_value = TYPE_MAX_VALUE (type); 1946 1947 /* If there's no HIGH value, then this is not a case range; it's 1948 just a simple case label. But that's just a degenerate case 1949 range. 1950 If the bounds are equal, turn this into the one-value case. */ 1951 if (!high || tree_int_cst_equal (low, high)) 1952 { 1953 /* If the simple case value is unreachable, ignore it. */ 1954 if ((TREE_CODE (min_value) == INTEGER_CST 1955 && tree_int_cst_compare (low, min_value) < 0) 1956 || (TREE_CODE (max_value) == INTEGER_CST 1957 && tree_int_cst_compare (low, max_value) > 0)) 1958 return head; 1959 low = fold_convert (type, low); 1960 high = low; 1961 } 1962 else 1963 { 1964 /* If the entire case range is unreachable, ignore it. */ 1965 if ((TREE_CODE (min_value) == INTEGER_CST 1966 && tree_int_cst_compare (high, min_value) < 0) 1967 || (TREE_CODE (max_value) == INTEGER_CST 1968 && tree_int_cst_compare (low, max_value) > 0)) 1969 return head; 1970 1971 /* If the lower bound is less than the index type's minimum 1972 value, truncate the range bounds. */ 1973 if (TREE_CODE (min_value) == INTEGER_CST 1974 && tree_int_cst_compare (low, min_value) < 0) 1975 low = min_value; 1976 low = fold_convert (type, low); 1977 1978 /* If the upper bound is greater than the index type's maximum 1979 value, truncate the range bounds. */ 1980 if (TREE_CODE (max_value) == INTEGER_CST 1981 && tree_int_cst_compare (high, max_value) > 0) 1982 high = max_value; 1983 high = fold_convert (type, high); 1984 } 1985 1986 1987 /* Add this label to the chain. Make sure to drop overflow flags. */ 1988 r = (struct case_node *) pool_alloc (case_node_pool); 1989 r->low = build_int_cst_wide (TREE_TYPE (low), TREE_INT_CST_LOW (low), 1990 TREE_INT_CST_HIGH (low)); 1991 r->high = build_int_cst_wide (TREE_TYPE (high), TREE_INT_CST_LOW (high), 1992 TREE_INT_CST_HIGH (high)); 1993 r->code_label = label; 1994 r->parent = r->left = NULL; 1995 r->right = head; 1996 return r; 1997 } 1998 1999 /* Maximum number of case bit tests. */ 2000 #define MAX_CASE_BIT_TESTS 3 2001 2002 /* By default, enable case bit tests on targets with ashlsi3. */ 2003 #ifndef CASE_USE_BIT_TESTS 2004 #define CASE_USE_BIT_TESTS (optab_handler (ashl_optab, word_mode) \ 2005 != CODE_FOR_nothing) 2006 #endif 2007 2008 2009 /* A case_bit_test represents a set of case nodes that may be 2010 selected from using a bit-wise comparison. HI and LO hold 2011 the integer to be tested against, LABEL contains the label 2012 to jump to upon success and BITS counts the number of case 2013 nodes handled by this test, typically the number of bits 2014 set in HI:LO. */ 2015 2016 struct case_bit_test 2017 { 2018 HOST_WIDE_INT hi; 2019 HOST_WIDE_INT lo; 2020 rtx label; 2021 int bits; 2022 }; 2023 2024 /* Determine whether "1 << x" is relatively cheap in word_mode. */ 2025 2026 static 2027 bool lshift_cheap_p (void) 2028 { 2029 static bool init[2] = {false, false}; 2030 static bool cheap[2] = {true, true}; 2031 2032 bool speed_p = optimize_insn_for_speed_p (); 2033 2034 if (!init[speed_p]) 2035 { 2036 rtx reg = gen_rtx_REG (word_mode, 10000); 2037 int cost = set_src_cost (gen_rtx_ASHIFT (word_mode, const1_rtx, reg), 2038 speed_p); 2039 cheap[speed_p] = cost < COSTS_N_INSNS (3); 2040 init[speed_p] = true; 2041 } 2042 2043 return cheap[speed_p]; 2044 } 2045 2046 /* Comparison function for qsort to order bit tests by decreasing 2047 number of case nodes, i.e. the node with the most cases gets 2048 tested first. */ 2049 2050 static int 2051 case_bit_test_cmp (const void *p1, const void *p2) 2052 { 2053 const struct case_bit_test *const d1 = (const struct case_bit_test *) p1; 2054 const struct case_bit_test *const d2 = (const struct case_bit_test *) p2; 2055 2056 if (d2->bits != d1->bits) 2057 return d2->bits - d1->bits; 2058 2059 /* Stabilize the sort. */ 2060 return CODE_LABEL_NUMBER (d2->label) - CODE_LABEL_NUMBER (d1->label); 2061 } 2062 2063 /* Expand a switch statement by a short sequence of bit-wise 2064 comparisons. "switch(x)" is effectively converted into 2065 "if ((1 << (x-MINVAL)) & CST)" where CST and MINVAL are 2066 integer constants. 2067 2068 INDEX_EXPR is the value being switched on, which is of 2069 type INDEX_TYPE. MINVAL is the lowest case value of in 2070 the case nodes, of INDEX_TYPE type, and RANGE is highest 2071 value minus MINVAL, also of type INDEX_TYPE. NODES is 2072 the set of case nodes, and DEFAULT_LABEL is the label to 2073 branch to should none of the cases match. 2074 2075 There *MUST* be MAX_CASE_BIT_TESTS or less unique case 2076 node targets. */ 2077 2078 static void 2079 emit_case_bit_tests (tree index_type, tree index_expr, tree minval, 2080 tree range, case_node_ptr nodes, rtx default_label) 2081 { 2082 struct case_bit_test test[MAX_CASE_BIT_TESTS]; 2083 enum machine_mode mode; 2084 rtx expr, index, label; 2085 unsigned int i,j,lo,hi; 2086 struct case_node *n; 2087 unsigned int count; 2088 2089 count = 0; 2090 for (n = nodes; n; n = n->right) 2091 { 2092 label = label_rtx (n->code_label); 2093 for (i = 0; i < count; i++) 2094 if (label == test[i].label) 2095 break; 2096 2097 if (i == count) 2098 { 2099 gcc_assert (count < MAX_CASE_BIT_TESTS); 2100 test[i].hi = 0; 2101 test[i].lo = 0; 2102 test[i].label = label; 2103 test[i].bits = 1; 2104 count++; 2105 } 2106 else 2107 test[i].bits++; 2108 2109 lo = tree_low_cst (fold_build2 (MINUS_EXPR, index_type, 2110 n->low, minval), 1); 2111 hi = tree_low_cst (fold_build2 (MINUS_EXPR, index_type, 2112 n->high, minval), 1); 2113 for (j = lo; j <= hi; j++) 2114 if (j >= HOST_BITS_PER_WIDE_INT) 2115 test[i].hi |= (HOST_WIDE_INT) 1 << (j - HOST_BITS_PER_INT); 2116 else 2117 test[i].lo |= (HOST_WIDE_INT) 1 << j; 2118 } 2119 2120 qsort (test, count, sizeof(*test), case_bit_test_cmp); 2121 2122 index_expr = fold_build2 (MINUS_EXPR, index_type, 2123 fold_convert (index_type, index_expr), 2124 fold_convert (index_type, minval)); 2125 index = expand_normal (index_expr); 2126 do_pending_stack_adjust (); 2127 2128 mode = TYPE_MODE (index_type); 2129 expr = expand_normal (range); 2130 if (default_label) 2131 emit_cmp_and_jump_insns (index, expr, GTU, NULL_RTX, mode, 1, 2132 default_label); 2133 2134 index = convert_to_mode (word_mode, index, 0); 2135 index = expand_binop (word_mode, ashl_optab, const1_rtx, 2136 index, NULL_RTX, 1, OPTAB_WIDEN); 2137 2138 for (i = 0; i < count; i++) 2139 { 2140 expr = immed_double_const (test[i].lo, test[i].hi, word_mode); 2141 expr = expand_binop (word_mode, and_optab, index, expr, 2142 NULL_RTX, 1, OPTAB_WIDEN); 2143 emit_cmp_and_jump_insns (expr, const0_rtx, NE, NULL_RTX, 2144 word_mode, 1, test[i].label); 2145 } 2146 2147 if (default_label) 2148 emit_jump (default_label); 2149 } 2150 2151 #ifndef HAVE_casesi 2152 #define HAVE_casesi 0 2153 #endif 2154 2155 #ifndef HAVE_tablejump 2156 #define HAVE_tablejump 0 2157 #endif 2158 2159 /* Return true if a switch should be expanded as a bit test. 2160 INDEX_EXPR is the index expression, RANGE is the difference between 2161 highest and lowest case, UNIQ is number of unique case node targets 2162 not counting the default case and COUNT is the number of comparisons 2163 needed, not counting the default case. */ 2164 bool 2165 expand_switch_using_bit_tests_p (tree index_expr, tree range, 2166 unsigned int uniq, unsigned int count) 2167 { 2168 return (CASE_USE_BIT_TESTS 2169 && ! TREE_CONSTANT (index_expr) 2170 && compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0 2171 && compare_tree_int (range, 0) > 0 2172 && lshift_cheap_p () 2173 && ((uniq == 1 && count >= 3) 2174 || (uniq == 2 && count >= 5) 2175 || (uniq == 3 && count >= 6))); 2176 } 2177 2178 /* Return the smallest number of different values for which it is best to use a 2179 jump-table instead of a tree of conditional branches. */ 2180 2181 static unsigned int 2182 case_values_threshold (void) 2183 { 2184 unsigned int threshold = PARAM_VALUE (PARAM_CASE_VALUES_THRESHOLD); 2185 2186 if (threshold == 0) 2187 threshold = targetm.case_values_threshold (); 2188 2189 return threshold; 2190 } 2191 2192 /* Terminate a case (Pascal/Ada) or switch (C) statement 2193 in which ORIG_INDEX is the expression to be tested. 2194 If ORIG_TYPE is not NULL, it is the original ORIG_INDEX 2195 type as given in the source before any compiler conversions. 2196 Generate the code to test it and jump to the right place. */ 2197 2198 void 2199 expand_case (gimple stmt) 2200 { 2201 tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE; 2202 rtx default_label = 0; 2203 struct case_node *n; 2204 unsigned int count, uniq; 2205 rtx index; 2206 rtx table_label; 2207 int ncases; 2208 rtx *labelvec; 2209 int i; 2210 rtx before_case, end, lab; 2211 2212 tree index_expr = gimple_switch_index (stmt); 2213 tree index_type = TREE_TYPE (index_expr); 2214 int unsignedp = TYPE_UNSIGNED (index_type); 2215 2216 /* The insn after which the case dispatch should finally 2217 be emitted. Zero for a dummy. */ 2218 rtx start; 2219 2220 /* A list of case labels; it is first built as a list and it may then 2221 be rearranged into a nearly balanced binary tree. */ 2222 struct case_node *case_list = 0; 2223 2224 /* Label to jump to if no case matches. */ 2225 tree default_label_decl = NULL_TREE; 2226 2227 alloc_pool case_node_pool = create_alloc_pool ("struct case_node pool", 2228 sizeof (struct case_node), 2229 100); 2230 2231 do_pending_stack_adjust (); 2232 2233 /* An ERROR_MARK occurs for various reasons including invalid data type. */ 2234 if (index_type != error_mark_node) 2235 { 2236 tree elt; 2237 bitmap label_bitmap; 2238 int stopi = 0; 2239 2240 /* cleanup_tree_cfg removes all SWITCH_EXPR with their index 2241 expressions being INTEGER_CST. */ 2242 gcc_assert (TREE_CODE (index_expr) != INTEGER_CST); 2243 2244 /* The default case, if ever taken, is the first element. */ 2245 elt = gimple_switch_label (stmt, 0); 2246 if (!CASE_LOW (elt) && !CASE_HIGH (elt)) 2247 { 2248 default_label_decl = CASE_LABEL (elt); 2249 stopi = 1; 2250 } 2251 2252 for (i = gimple_switch_num_labels (stmt) - 1; i >= stopi; --i) 2253 { 2254 tree low, high; 2255 elt = gimple_switch_label (stmt, i); 2256 2257 low = CASE_LOW (elt); 2258 gcc_assert (low); 2259 high = CASE_HIGH (elt); 2260 2261 /* Discard empty ranges. */ 2262 if (high && tree_int_cst_lt (high, low)) 2263 continue; 2264 2265 case_list = add_case_node (case_list, index_type, low, high, 2266 CASE_LABEL (elt), case_node_pool); 2267 } 2268 2269 2270 before_case = start = get_last_insn (); 2271 if (default_label_decl) 2272 default_label = label_rtx (default_label_decl); 2273 2274 /* Get upper and lower bounds of case values. */ 2275 2276 uniq = 0; 2277 count = 0; 2278 label_bitmap = BITMAP_ALLOC (NULL); 2279 for (n = case_list; n; n = n->right) 2280 { 2281 /* Count the elements and track the largest and smallest 2282 of them (treating them as signed even if they are not). */ 2283 if (count++ == 0) 2284 { 2285 minval = n->low; 2286 maxval = n->high; 2287 } 2288 else 2289 { 2290 if (tree_int_cst_lt (n->low, minval)) 2291 minval = n->low; 2292 if (tree_int_cst_lt (maxval, n->high)) 2293 maxval = n->high; 2294 } 2295 /* A range counts double, since it requires two compares. */ 2296 if (! tree_int_cst_equal (n->low, n->high)) 2297 count++; 2298 2299 /* If we have not seen this label yet, then increase the 2300 number of unique case node targets seen. */ 2301 lab = label_rtx (n->code_label); 2302 if (bitmap_set_bit (label_bitmap, CODE_LABEL_NUMBER (lab))) 2303 uniq++; 2304 } 2305 2306 BITMAP_FREE (label_bitmap); 2307 2308 /* cleanup_tree_cfg removes all SWITCH_EXPR with a single 2309 destination, such as one with a default case only. However, 2310 it doesn't remove cases that are out of range for the switch 2311 type, so we may still get a zero here. */ 2312 if (count == 0) 2313 { 2314 if (default_label) 2315 emit_jump (default_label); 2316 free_alloc_pool (case_node_pool); 2317 return; 2318 } 2319 2320 /* Compute span of values. */ 2321 range = fold_build2 (MINUS_EXPR, index_type, maxval, minval); 2322 2323 /* Try implementing this switch statement by a short sequence of 2324 bit-wise comparisons. However, we let the binary-tree case 2325 below handle constant index expressions. */ 2326 if (expand_switch_using_bit_tests_p (index_expr, range, uniq, count)) 2327 { 2328 /* Optimize the case where all the case values fit in a 2329 word without having to subtract MINVAL. In this case, 2330 we can optimize away the subtraction. */ 2331 if (compare_tree_int (minval, 0) > 0 2332 && compare_tree_int (maxval, GET_MODE_BITSIZE (word_mode)) < 0) 2333 { 2334 minval = build_int_cst (index_type, 0); 2335 range = maxval; 2336 } 2337 emit_case_bit_tests (index_type, index_expr, minval, range, 2338 case_list, default_label); 2339 } 2340 2341 /* If range of values is much bigger than number of values, 2342 make a sequence of conditional branches instead of a dispatch. 2343 If the switch-index is a constant, do it this way 2344 because we can optimize it. */ 2345 2346 else if (count < case_values_threshold () 2347 || compare_tree_int (range, 2348 (optimize_insn_for_size_p () ? 3 : 10) * count) > 0 2349 /* RANGE may be signed, and really large ranges will show up 2350 as negative numbers. */ 2351 || compare_tree_int (range, 0) < 0 2352 #ifndef ASM_OUTPUT_ADDR_DIFF_ELT 2353 || flag_pic 2354 #endif 2355 || !flag_jump_tables 2356 || TREE_CONSTANT (index_expr) 2357 /* If neither casesi or tablejump is available, we can 2358 only go this way. */ 2359 || (!HAVE_casesi && !HAVE_tablejump)) 2360 { 2361 index = expand_normal (index_expr); 2362 2363 /* If the index is a short or char that we do not have 2364 an insn to handle comparisons directly, convert it to 2365 a full integer now, rather than letting each comparison 2366 generate the conversion. */ 2367 2368 if (GET_MODE_CLASS (GET_MODE (index)) == MODE_INT 2369 && ! have_insn_for (COMPARE, GET_MODE (index))) 2370 { 2371 enum machine_mode wider_mode; 2372 for (wider_mode = GET_MODE (index); wider_mode != VOIDmode; 2373 wider_mode = GET_MODE_WIDER_MODE (wider_mode)) 2374 if (have_insn_for (COMPARE, wider_mode)) 2375 { 2376 index = convert_to_mode (wider_mode, index, unsignedp); 2377 break; 2378 } 2379 } 2380 2381 do_pending_stack_adjust (); 2382 2383 if (MEM_P (index)) 2384 index = copy_to_reg (index); 2385 2386 /* We generate a binary decision tree to select the 2387 appropriate target code. This is done as follows: 2388 2389 The list of cases is rearranged into a binary tree, 2390 nearly optimal assuming equal probability for each case. 2391 2392 The tree is transformed into RTL, eliminating 2393 redundant test conditions at the same time. 2394 2395 If program flow could reach the end of the 2396 decision tree an unconditional jump to the 2397 default code is emitted. */ 2398 2399 use_cost_table = estimate_case_costs (case_list); 2400 balance_case_nodes (&case_list, NULL); 2401 emit_case_nodes (index, case_list, default_label, index_type); 2402 if (default_label) 2403 emit_jump (default_label); 2404 } 2405 else 2406 { 2407 rtx fallback_label = label_rtx (case_list->code_label); 2408 table_label = gen_label_rtx (); 2409 if (! try_casesi (index_type, index_expr, minval, range, 2410 table_label, default_label, fallback_label)) 2411 { 2412 bool ok; 2413 2414 /* Index jumptables from zero for suitable values of 2415 minval to avoid a subtraction. */ 2416 if (optimize_insn_for_speed_p () 2417 && compare_tree_int (minval, 0) > 0 2418 && compare_tree_int (minval, 3) < 0) 2419 { 2420 minval = build_int_cst (index_type, 0); 2421 range = maxval; 2422 } 2423 2424 ok = try_tablejump (index_type, index_expr, minval, range, 2425 table_label, default_label); 2426 gcc_assert (ok); 2427 } 2428 2429 /* Get table of labels to jump to, in order of case index. */ 2430 2431 ncases = tree_low_cst (range, 0) + 1; 2432 labelvec = XALLOCAVEC (rtx, ncases); 2433 memset (labelvec, 0, ncases * sizeof (rtx)); 2434 2435 for (n = case_list; n; n = n->right) 2436 { 2437 /* Compute the low and high bounds relative to the minimum 2438 value since that should fit in a HOST_WIDE_INT while the 2439 actual values may not. */ 2440 HOST_WIDE_INT i_low 2441 = tree_low_cst (fold_build2 (MINUS_EXPR, index_type, 2442 n->low, minval), 1); 2443 HOST_WIDE_INT i_high 2444 = tree_low_cst (fold_build2 (MINUS_EXPR, index_type, 2445 n->high, minval), 1); 2446 HOST_WIDE_INT i; 2447 2448 for (i = i_low; i <= i_high; i ++) 2449 labelvec[i] 2450 = gen_rtx_LABEL_REF (Pmode, label_rtx (n->code_label)); 2451 } 2452 2453 /* Fill in the gaps with the default. We may have gaps at 2454 the beginning if we tried to avoid the minval subtraction, 2455 so substitute some label even if the default label was 2456 deemed unreachable. */ 2457 if (!default_label) 2458 default_label = fallback_label; 2459 for (i = 0; i < ncases; i++) 2460 if (labelvec[i] == 0) 2461 labelvec[i] = gen_rtx_LABEL_REF (Pmode, default_label); 2462 2463 /* Output the table. */ 2464 emit_label (table_label); 2465 2466 if (CASE_VECTOR_PC_RELATIVE || flag_pic) 2467 emit_jump_insn (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE, 2468 gen_rtx_LABEL_REF (Pmode, table_label), 2469 gen_rtvec_v (ncases, labelvec), 2470 const0_rtx, const0_rtx)); 2471 else 2472 emit_jump_insn (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE, 2473 gen_rtvec_v (ncases, labelvec))); 2474 2475 /* Record no drop-through after the table. */ 2476 emit_barrier (); 2477 } 2478 2479 before_case = NEXT_INSN (before_case); 2480 end = get_last_insn (); 2481 reorder_insns (before_case, end, start); 2482 } 2483 2484 free_temp_slots (); 2485 free_alloc_pool (case_node_pool); 2486 } 2487 2488 /* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE. */ 2489 2490 static void 2491 do_jump_if_equal (enum machine_mode mode, rtx op0, rtx op1, rtx label, 2492 int unsignedp) 2493 { 2494 do_compare_rtx_and_jump (op0, op1, EQ, unsignedp, mode, 2495 NULL_RTX, NULL_RTX, label, -1); 2496 } 2497 2498 /* Not all case values are encountered equally. This function 2499 uses a heuristic to weight case labels, in cases where that 2500 looks like a reasonable thing to do. 2501 2502 Right now, all we try to guess is text, and we establish the 2503 following weights: 2504 2505 chars above space: 16 2506 digits: 16 2507 default: 12 2508 space, punct: 8 2509 tab: 4 2510 newline: 2 2511 other "\" chars: 1 2512 remaining chars: 0 2513 2514 If we find any cases in the switch that are not either -1 or in the range 2515 of valid ASCII characters, or are control characters other than those 2516 commonly used with "\", don't treat this switch scanning text. 2517 2518 Return 1 if these nodes are suitable for cost estimation, otherwise 2519 return 0. */ 2520 2521 static int 2522 estimate_case_costs (case_node_ptr node) 2523 { 2524 tree min_ascii = integer_minus_one_node; 2525 tree max_ascii = build_int_cst (TREE_TYPE (node->high), 127); 2526 case_node_ptr n; 2527 int i; 2528 2529 /* If we haven't already made the cost table, make it now. Note that the 2530 lower bound of the table is -1, not zero. */ 2531 2532 if (! cost_table_initialized) 2533 { 2534 cost_table_initialized = 1; 2535 2536 for (i = 0; i < 128; i++) 2537 { 2538 if (ISALNUM (i)) 2539 COST_TABLE (i) = 16; 2540 else if (ISPUNCT (i)) 2541 COST_TABLE (i) = 8; 2542 else if (ISCNTRL (i)) 2543 COST_TABLE (i) = -1; 2544 } 2545 2546 COST_TABLE (' ') = 8; 2547 COST_TABLE ('\t') = 4; 2548 COST_TABLE ('\0') = 4; 2549 COST_TABLE ('\n') = 2; 2550 COST_TABLE ('\f') = 1; 2551 COST_TABLE ('\v') = 1; 2552 COST_TABLE ('\b') = 1; 2553 } 2554 2555 /* See if all the case expressions look like text. It is text if the 2556 constant is >= -1 and the highest constant is <= 127. Do all comparisons 2557 as signed arithmetic since we don't want to ever access cost_table with a 2558 value less than -1. Also check that none of the constants in a range 2559 are strange control characters. */ 2560 2561 for (n = node; n; n = n->right) 2562 { 2563 if (tree_int_cst_lt (n->low, min_ascii) 2564 || tree_int_cst_lt (max_ascii, n->high)) 2565 return 0; 2566 2567 for (i = (HOST_WIDE_INT) TREE_INT_CST_LOW (n->low); 2568 i <= (HOST_WIDE_INT) TREE_INT_CST_LOW (n->high); i++) 2569 if (COST_TABLE (i) < 0) 2570 return 0; 2571 } 2572 2573 /* All interesting values are within the range of interesting 2574 ASCII characters. */ 2575 return 1; 2576 } 2577 2578 /* Take an ordered list of case nodes 2579 and transform them into a near optimal binary tree, 2580 on the assumption that any target code selection value is as 2581 likely as any other. 2582 2583 The transformation is performed by splitting the ordered 2584 list into two equal sections plus a pivot. The parts are 2585 then attached to the pivot as left and right branches. Each 2586 branch is then transformed recursively. */ 2587 2588 static void 2589 balance_case_nodes (case_node_ptr *head, case_node_ptr parent) 2590 { 2591 case_node_ptr np; 2592 2593 np = *head; 2594 if (np) 2595 { 2596 int cost = 0; 2597 int i = 0; 2598 int ranges = 0; 2599 case_node_ptr *npp; 2600 case_node_ptr left; 2601 2602 /* Count the number of entries on branch. Also count the ranges. */ 2603 2604 while (np) 2605 { 2606 if (!tree_int_cst_equal (np->low, np->high)) 2607 { 2608 ranges++; 2609 if (use_cost_table) 2610 cost += COST_TABLE (TREE_INT_CST_LOW (np->high)); 2611 } 2612 2613 if (use_cost_table) 2614 cost += COST_TABLE (TREE_INT_CST_LOW (np->low)); 2615 2616 i++; 2617 np = np->right; 2618 } 2619 2620 if (i > 2) 2621 { 2622 /* Split this list if it is long enough for that to help. */ 2623 npp = head; 2624 left = *npp; 2625 if (use_cost_table) 2626 { 2627 /* Find the place in the list that bisects the list's total cost, 2628 Here I gets half the total cost. */ 2629 int n_moved = 0; 2630 i = (cost + 1) / 2; 2631 while (1) 2632 { 2633 /* Skip nodes while their cost does not reach that amount. */ 2634 if (!tree_int_cst_equal ((*npp)->low, (*npp)->high)) 2635 i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->high)); 2636 i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->low)); 2637 if (i <= 0) 2638 break; 2639 npp = &(*npp)->right; 2640 n_moved += 1; 2641 } 2642 if (n_moved == 0) 2643 { 2644 /* Leave this branch lopsided, but optimize left-hand 2645 side and fill in `parent' fields for right-hand side. */ 2646 np = *head; 2647 np->parent = parent; 2648 balance_case_nodes (&np->left, np); 2649 for (; np->right; np = np->right) 2650 np->right->parent = np; 2651 return; 2652 } 2653 } 2654 /* If there are just three nodes, split at the middle one. */ 2655 else if (i == 3) 2656 npp = &(*npp)->right; 2657 else 2658 { 2659 /* Find the place in the list that bisects the list's total cost, 2660 where ranges count as 2. 2661 Here I gets half the total cost. */ 2662 i = (i + ranges + 1) / 2; 2663 while (1) 2664 { 2665 /* Skip nodes while their cost does not reach that amount. */ 2666 if (!tree_int_cst_equal ((*npp)->low, (*npp)->high)) 2667 i--; 2668 i--; 2669 if (i <= 0) 2670 break; 2671 npp = &(*npp)->right; 2672 } 2673 } 2674 *head = np = *npp; 2675 *npp = 0; 2676 np->parent = parent; 2677 np->left = left; 2678 2679 /* Optimize each of the two split parts. */ 2680 balance_case_nodes (&np->left, np); 2681 balance_case_nodes (&np->right, np); 2682 } 2683 else 2684 { 2685 /* Else leave this branch as one level, 2686 but fill in `parent' fields. */ 2687 np = *head; 2688 np->parent = parent; 2689 for (; np->right; np = np->right) 2690 np->right->parent = np; 2691 } 2692 } 2693 } 2694 2695 /* Search the parent sections of the case node tree 2696 to see if a test for the lower bound of NODE would be redundant. 2697 INDEX_TYPE is the type of the index expression. 2698 2699 The instructions to generate the case decision tree are 2700 output in the same order as nodes are processed so it is 2701 known that if a parent node checks the range of the current 2702 node minus one that the current node is bounded at its lower 2703 span. Thus the test would be redundant. */ 2704 2705 static int 2706 node_has_low_bound (case_node_ptr node, tree index_type) 2707 { 2708 tree low_minus_one; 2709 case_node_ptr pnode; 2710 2711 /* If the lower bound of this node is the lowest value in the index type, 2712 we need not test it. */ 2713 2714 if (tree_int_cst_equal (node->low, TYPE_MIN_VALUE (index_type))) 2715 return 1; 2716 2717 /* If this node has a left branch, the value at the left must be less 2718 than that at this node, so it cannot be bounded at the bottom and 2719 we need not bother testing any further. */ 2720 2721 if (node->left) 2722 return 0; 2723 2724 low_minus_one = fold_build2 (MINUS_EXPR, TREE_TYPE (node->low), 2725 node->low, 2726 build_int_cst (TREE_TYPE (node->low), 1)); 2727 2728 /* If the subtraction above overflowed, we can't verify anything. 2729 Otherwise, look for a parent that tests our value - 1. */ 2730 2731 if (! tree_int_cst_lt (low_minus_one, node->low)) 2732 return 0; 2733 2734 for (pnode = node->parent; pnode; pnode = pnode->parent) 2735 if (tree_int_cst_equal (low_minus_one, pnode->high)) 2736 return 1; 2737 2738 return 0; 2739 } 2740 2741 /* Search the parent sections of the case node tree 2742 to see if a test for the upper bound of NODE would be redundant. 2743 INDEX_TYPE is the type of the index expression. 2744 2745 The instructions to generate the case decision tree are 2746 output in the same order as nodes are processed so it is 2747 known that if a parent node checks the range of the current 2748 node plus one that the current node is bounded at its upper 2749 span. Thus the test would be redundant. */ 2750 2751 static int 2752 node_has_high_bound (case_node_ptr node, tree index_type) 2753 { 2754 tree high_plus_one; 2755 case_node_ptr pnode; 2756 2757 /* If there is no upper bound, obviously no test is needed. */ 2758 2759 if (TYPE_MAX_VALUE (index_type) == NULL) 2760 return 1; 2761 2762 /* If the upper bound of this node is the highest value in the type 2763 of the index expression, we need not test against it. */ 2764 2765 if (tree_int_cst_equal (node->high, TYPE_MAX_VALUE (index_type))) 2766 return 1; 2767 2768 /* If this node has a right branch, the value at the right must be greater 2769 than that at this node, so it cannot be bounded at the top and 2770 we need not bother testing any further. */ 2771 2772 if (node->right) 2773 return 0; 2774 2775 high_plus_one = fold_build2 (PLUS_EXPR, TREE_TYPE (node->high), 2776 node->high, 2777 build_int_cst (TREE_TYPE (node->high), 1)); 2778 2779 /* If the addition above overflowed, we can't verify anything. 2780 Otherwise, look for a parent that tests our value + 1. */ 2781 2782 if (! tree_int_cst_lt (node->high, high_plus_one)) 2783 return 0; 2784 2785 for (pnode = node->parent; pnode; pnode = pnode->parent) 2786 if (tree_int_cst_equal (high_plus_one, pnode->low)) 2787 return 1; 2788 2789 return 0; 2790 } 2791 2792 /* Search the parent sections of the 2793 case node tree to see if both tests for the upper and lower 2794 bounds of NODE would be redundant. */ 2795 2796 static int 2797 node_is_bounded (case_node_ptr node, tree index_type) 2798 { 2799 return (node_has_low_bound (node, index_type) 2800 && node_has_high_bound (node, index_type)); 2801 } 2802 2803 /* Emit step-by-step code to select a case for the value of INDEX. 2804 The thus generated decision tree follows the form of the 2805 case-node binary tree NODE, whose nodes represent test conditions. 2806 INDEX_TYPE is the type of the index of the switch. 2807 2808 Care is taken to prune redundant tests from the decision tree 2809 by detecting any boundary conditions already checked by 2810 emitted rtx. (See node_has_high_bound, node_has_low_bound 2811 and node_is_bounded, above.) 2812 2813 Where the test conditions can be shown to be redundant we emit 2814 an unconditional jump to the target code. As a further 2815 optimization, the subordinates of a tree node are examined to 2816 check for bounded nodes. In this case conditional and/or 2817 unconditional jumps as a result of the boundary check for the 2818 current node are arranged to target the subordinates associated 2819 code for out of bound conditions on the current node. 2820 2821 We can assume that when control reaches the code generated here, 2822 the index value has already been compared with the parents 2823 of this node, and determined to be on the same side of each parent 2824 as this node is. Thus, if this node tests for the value 51, 2825 and a parent tested for 52, we don't need to consider 2826 the possibility of a value greater than 51. If another parent 2827 tests for the value 50, then this node need not test anything. */ 2828 2829 static void 2830 emit_case_nodes (rtx index, case_node_ptr node, rtx default_label, 2831 tree index_type) 2832 { 2833 /* If INDEX has an unsigned type, we must make unsigned branches. */ 2834 int unsignedp = TYPE_UNSIGNED (index_type); 2835 enum machine_mode mode = GET_MODE (index); 2836 enum machine_mode imode = TYPE_MODE (index_type); 2837 2838 /* Handle indices detected as constant during RTL expansion. */ 2839 if (mode == VOIDmode) 2840 mode = imode; 2841 2842 /* See if our parents have already tested everything for us. 2843 If they have, emit an unconditional jump for this node. */ 2844 if (node_is_bounded (node, index_type)) 2845 emit_jump (label_rtx (node->code_label)); 2846 2847 else if (tree_int_cst_equal (node->low, node->high)) 2848 { 2849 /* Node is single valued. First see if the index expression matches 2850 this node and then check our children, if any. */ 2851 2852 do_jump_if_equal (mode, index, 2853 convert_modes (mode, imode, 2854 expand_normal (node->low), 2855 unsignedp), 2856 label_rtx (node->code_label), unsignedp); 2857 2858 if (node->right != 0 && node->left != 0) 2859 { 2860 /* This node has children on both sides. 2861 Dispatch to one side or the other 2862 by comparing the index value with this node's value. 2863 If one subtree is bounded, check that one first, 2864 so we can avoid real branches in the tree. */ 2865 2866 if (node_is_bounded (node->right, index_type)) 2867 { 2868 emit_cmp_and_jump_insns (index, 2869 convert_modes 2870 (mode, imode, 2871 expand_normal (node->high), 2872 unsignedp), 2873 GT, NULL_RTX, mode, unsignedp, 2874 label_rtx (node->right->code_label)); 2875 emit_case_nodes (index, node->left, default_label, index_type); 2876 } 2877 2878 else if (node_is_bounded (node->left, index_type)) 2879 { 2880 emit_cmp_and_jump_insns (index, 2881 convert_modes 2882 (mode, imode, 2883 expand_normal (node->high), 2884 unsignedp), 2885 LT, NULL_RTX, mode, unsignedp, 2886 label_rtx (node->left->code_label)); 2887 emit_case_nodes (index, node->right, default_label, index_type); 2888 } 2889 2890 /* If both children are single-valued cases with no 2891 children, finish up all the work. This way, we can save 2892 one ordered comparison. */ 2893 else if (tree_int_cst_equal (node->right->low, node->right->high) 2894 && node->right->left == 0 2895 && node->right->right == 0 2896 && tree_int_cst_equal (node->left->low, node->left->high) 2897 && node->left->left == 0 2898 && node->left->right == 0) 2899 { 2900 /* Neither node is bounded. First distinguish the two sides; 2901 then emit the code for one side at a time. */ 2902 2903 /* See if the value matches what the right hand side 2904 wants. */ 2905 do_jump_if_equal (mode, index, 2906 convert_modes (mode, imode, 2907 expand_normal (node->right->low), 2908 unsignedp), 2909 label_rtx (node->right->code_label), 2910 unsignedp); 2911 2912 /* See if the value matches what the left hand side 2913 wants. */ 2914 do_jump_if_equal (mode, index, 2915 convert_modes (mode, imode, 2916 expand_normal (node->left->low), 2917 unsignedp), 2918 label_rtx (node->left->code_label), 2919 unsignedp); 2920 } 2921 2922 else 2923 { 2924 /* Neither node is bounded. First distinguish the two sides; 2925 then emit the code for one side at a time. */ 2926 2927 tree test_label 2928 = build_decl (CURR_INSN_LOCATION, 2929 LABEL_DECL, NULL_TREE, NULL_TREE); 2930 2931 /* See if the value is on the right. */ 2932 emit_cmp_and_jump_insns (index, 2933 convert_modes 2934 (mode, imode, 2935 expand_normal (node->high), 2936 unsignedp), 2937 GT, NULL_RTX, mode, unsignedp, 2938 label_rtx (test_label)); 2939 2940 /* Value must be on the left. 2941 Handle the left-hand subtree. */ 2942 emit_case_nodes (index, node->left, default_label, index_type); 2943 /* If left-hand subtree does nothing, 2944 go to default. */ 2945 if (default_label) 2946 emit_jump (default_label); 2947 2948 /* Code branches here for the right-hand subtree. */ 2949 expand_label (test_label); 2950 emit_case_nodes (index, node->right, default_label, index_type); 2951 } 2952 } 2953 2954 else if (node->right != 0 && node->left == 0) 2955 { 2956 /* Here we have a right child but no left so we issue a conditional 2957 branch to default and process the right child. 2958 2959 Omit the conditional branch to default if the right child 2960 does not have any children and is single valued; it would 2961 cost too much space to save so little time. */ 2962 2963 if (node->right->right || node->right->left 2964 || !tree_int_cst_equal (node->right->low, node->right->high)) 2965 { 2966 if (!node_has_low_bound (node, index_type)) 2967 { 2968 emit_cmp_and_jump_insns (index, 2969 convert_modes 2970 (mode, imode, 2971 expand_normal (node->high), 2972 unsignedp), 2973 LT, NULL_RTX, mode, unsignedp, 2974 default_label); 2975 } 2976 2977 emit_case_nodes (index, node->right, default_label, index_type); 2978 } 2979 else 2980 /* We cannot process node->right normally 2981 since we haven't ruled out the numbers less than 2982 this node's value. So handle node->right explicitly. */ 2983 do_jump_if_equal (mode, index, 2984 convert_modes 2985 (mode, imode, 2986 expand_normal (node->right->low), 2987 unsignedp), 2988 label_rtx (node->right->code_label), unsignedp); 2989 } 2990 2991 else if (node->right == 0 && node->left != 0) 2992 { 2993 /* Just one subtree, on the left. */ 2994 if (node->left->left || node->left->right 2995 || !tree_int_cst_equal (node->left->low, node->left->high)) 2996 { 2997 if (!node_has_high_bound (node, index_type)) 2998 { 2999 emit_cmp_and_jump_insns (index, 3000 convert_modes 3001 (mode, imode, 3002 expand_normal (node->high), 3003 unsignedp), 3004 GT, NULL_RTX, mode, unsignedp, 3005 default_label); 3006 } 3007 3008 emit_case_nodes (index, node->left, default_label, index_type); 3009 } 3010 else 3011 /* We cannot process node->left normally 3012 since we haven't ruled out the numbers less than 3013 this node's value. So handle node->left explicitly. */ 3014 do_jump_if_equal (mode, index, 3015 convert_modes 3016 (mode, imode, 3017 expand_normal (node->left->low), 3018 unsignedp), 3019 label_rtx (node->left->code_label), unsignedp); 3020 } 3021 } 3022 else 3023 { 3024 /* Node is a range. These cases are very similar to those for a single 3025 value, except that we do not start by testing whether this node 3026 is the one to branch to. */ 3027 3028 if (node->right != 0 && node->left != 0) 3029 { 3030 /* Node has subtrees on both sides. 3031 If the right-hand subtree is bounded, 3032 test for it first, since we can go straight there. 3033 Otherwise, we need to make a branch in the control structure, 3034 then handle the two subtrees. */ 3035 tree test_label = 0; 3036 3037 if (node_is_bounded (node->right, index_type)) 3038 /* Right hand node is fully bounded so we can eliminate any 3039 testing and branch directly to the target code. */ 3040 emit_cmp_and_jump_insns (index, 3041 convert_modes 3042 (mode, imode, 3043 expand_normal (node->high), 3044 unsignedp), 3045 GT, NULL_RTX, mode, unsignedp, 3046 label_rtx (node->right->code_label)); 3047 else 3048 { 3049 /* Right hand node requires testing. 3050 Branch to a label where we will handle it later. */ 3051 3052 test_label = build_decl (CURR_INSN_LOCATION, 3053 LABEL_DECL, NULL_TREE, NULL_TREE); 3054 emit_cmp_and_jump_insns (index, 3055 convert_modes 3056 (mode, imode, 3057 expand_normal (node->high), 3058 unsignedp), 3059 GT, NULL_RTX, mode, unsignedp, 3060 label_rtx (test_label)); 3061 } 3062 3063 /* Value belongs to this node or to the left-hand subtree. */ 3064 3065 emit_cmp_and_jump_insns (index, 3066 convert_modes 3067 (mode, imode, 3068 expand_normal (node->low), 3069 unsignedp), 3070 GE, NULL_RTX, mode, unsignedp, 3071 label_rtx (node->code_label)); 3072 3073 /* Handle the left-hand subtree. */ 3074 emit_case_nodes (index, node->left, default_label, index_type); 3075 3076 /* If right node had to be handled later, do that now. */ 3077 3078 if (test_label) 3079 { 3080 /* If the left-hand subtree fell through, 3081 don't let it fall into the right-hand subtree. */ 3082 if (default_label) 3083 emit_jump (default_label); 3084 3085 expand_label (test_label); 3086 emit_case_nodes (index, node->right, default_label, index_type); 3087 } 3088 } 3089 3090 else if (node->right != 0 && node->left == 0) 3091 { 3092 /* Deal with values to the left of this node, 3093 if they are possible. */ 3094 if (!node_has_low_bound (node, index_type)) 3095 { 3096 emit_cmp_and_jump_insns (index, 3097 convert_modes 3098 (mode, imode, 3099 expand_normal (node->low), 3100 unsignedp), 3101 LT, NULL_RTX, mode, unsignedp, 3102 default_label); 3103 } 3104 3105 /* Value belongs to this node or to the right-hand subtree. */ 3106 3107 emit_cmp_and_jump_insns (index, 3108 convert_modes 3109 (mode, imode, 3110 expand_normal (node->high), 3111 unsignedp), 3112 LE, NULL_RTX, mode, unsignedp, 3113 label_rtx (node->code_label)); 3114 3115 emit_case_nodes (index, node->right, default_label, index_type); 3116 } 3117 3118 else if (node->right == 0 && node->left != 0) 3119 { 3120 /* Deal with values to the right of this node, 3121 if they are possible. */ 3122 if (!node_has_high_bound (node, index_type)) 3123 { 3124 emit_cmp_and_jump_insns (index, 3125 convert_modes 3126 (mode, imode, 3127 expand_normal (node->high), 3128 unsignedp), 3129 GT, NULL_RTX, mode, unsignedp, 3130 default_label); 3131 } 3132 3133 /* Value belongs to this node or to the left-hand subtree. */ 3134 3135 emit_cmp_and_jump_insns (index, 3136 convert_modes 3137 (mode, imode, 3138 expand_normal (node->low), 3139 unsignedp), 3140 GE, NULL_RTX, mode, unsignedp, 3141 label_rtx (node->code_label)); 3142 3143 emit_case_nodes (index, node->left, default_label, index_type); 3144 } 3145 3146 else 3147 { 3148 /* Node has no children so we check low and high bounds to remove 3149 redundant tests. Only one of the bounds can exist, 3150 since otherwise this node is bounded--a case tested already. */ 3151 int high_bound = node_has_high_bound (node, index_type); 3152 int low_bound = node_has_low_bound (node, index_type); 3153 3154 if (!high_bound && low_bound) 3155 { 3156 emit_cmp_and_jump_insns (index, 3157 convert_modes 3158 (mode, imode, 3159 expand_normal (node->high), 3160 unsignedp), 3161 GT, NULL_RTX, mode, unsignedp, 3162 default_label); 3163 } 3164 3165 else if (!low_bound && high_bound) 3166 { 3167 emit_cmp_and_jump_insns (index, 3168 convert_modes 3169 (mode, imode, 3170 expand_normal (node->low), 3171 unsignedp), 3172 LT, NULL_RTX, mode, unsignedp, 3173 default_label); 3174 } 3175 else if (!low_bound && !high_bound) 3176 { 3177 /* Widen LOW and HIGH to the same width as INDEX. */ 3178 tree type = lang_hooks.types.type_for_mode (mode, unsignedp); 3179 tree low = build1 (CONVERT_EXPR, type, node->low); 3180 tree high = build1 (CONVERT_EXPR, type, node->high); 3181 rtx low_rtx, new_index, new_bound; 3182 3183 /* Instead of doing two branches, emit one unsigned branch for 3184 (index-low) > (high-low). */ 3185 low_rtx = expand_expr (low, NULL_RTX, mode, EXPAND_NORMAL); 3186 new_index = expand_simple_binop (mode, MINUS, index, low_rtx, 3187 NULL_RTX, unsignedp, 3188 OPTAB_WIDEN); 3189 new_bound = expand_expr (fold_build2 (MINUS_EXPR, type, 3190 high, low), 3191 NULL_RTX, mode, EXPAND_NORMAL); 3192 3193 emit_cmp_and_jump_insns (new_index, new_bound, GT, NULL_RTX, 3194 mode, 1, default_label); 3195 } 3196 3197 emit_jump (label_rtx (node->code_label)); 3198 } 3199 } 3200 } 3201