1 /* Pass computing data for optimizing stdarg functions. 2 Copyright (C) 2004, 2005, 2007, 2008, 2009, 2010, 2011 3 Free Software Foundation, Inc. 4 Contributed by Jakub Jelinek <jakub@redhat.com> 5 6 This file is part of GCC. 7 8 GCC is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 3, or (at your option) 11 any later version. 12 13 GCC is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License 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 #include "config.h" 23 #include "system.h" 24 #include "coretypes.h" 25 #include "tm.h" 26 #include "tree.h" 27 #include "function.h" 28 #include "langhooks.h" 29 #include "gimple-pretty-print.h" 30 #include "target.h" 31 #include "tree-flow.h" 32 #include "tree-pass.h" 33 #include "tree-stdarg.h" 34 35 /* A simple pass that attempts to optimize stdarg functions on architectures 36 that need to save register arguments to stack on entry to stdarg functions. 37 If the function doesn't use any va_start macros, no registers need to 38 be saved. If va_start macros are used, the va_list variables don't escape 39 the function, it is only necessary to save registers that will be used 40 in va_arg macros. E.g. if va_arg is only used with integral types 41 in the function, floating point registers don't need to be saved, etc. */ 42 43 44 /* Return true if basic block VA_ARG_BB is dominated by VA_START_BB and 45 is executed at most as many times as VA_START_BB. */ 46 47 static bool 48 reachable_at_most_once (basic_block va_arg_bb, basic_block va_start_bb) 49 { 50 VEC (edge, heap) *stack = NULL; 51 edge e; 52 edge_iterator ei; 53 sbitmap visited; 54 bool ret; 55 56 if (va_arg_bb == va_start_bb) 57 return true; 58 59 if (! dominated_by_p (CDI_DOMINATORS, va_arg_bb, va_start_bb)) 60 return false; 61 62 visited = sbitmap_alloc (last_basic_block); 63 sbitmap_zero (visited); 64 ret = true; 65 66 FOR_EACH_EDGE (e, ei, va_arg_bb->preds) 67 VEC_safe_push (edge, heap, stack, e); 68 69 while (! VEC_empty (edge, stack)) 70 { 71 basic_block src; 72 73 e = VEC_pop (edge, stack); 74 src = e->src; 75 76 if (e->flags & EDGE_COMPLEX) 77 { 78 ret = false; 79 break; 80 } 81 82 if (src == va_start_bb) 83 continue; 84 85 /* va_arg_bb can be executed more times than va_start_bb. */ 86 if (src == va_arg_bb) 87 { 88 ret = false; 89 break; 90 } 91 92 gcc_assert (src != ENTRY_BLOCK_PTR); 93 94 if (! TEST_BIT (visited, src->index)) 95 { 96 SET_BIT (visited, src->index); 97 FOR_EACH_EDGE (e, ei, src->preds) 98 VEC_safe_push (edge, heap, stack, e); 99 } 100 } 101 102 VEC_free (edge, heap, stack); 103 sbitmap_free (visited); 104 return ret; 105 } 106 107 108 /* For statement COUNTER = RHS, if RHS is COUNTER + constant, 109 return constant, otherwise return (unsigned HOST_WIDE_INT) -1. 110 GPR_P is true if this is GPR counter. */ 111 112 static unsigned HOST_WIDE_INT 113 va_list_counter_bump (struct stdarg_info *si, tree counter, tree rhs, 114 bool gpr_p) 115 { 116 tree lhs, orig_lhs; 117 gimple stmt; 118 unsigned HOST_WIDE_INT ret = 0, val, counter_val; 119 unsigned int max_size; 120 121 if (si->offsets == NULL) 122 { 123 unsigned int i; 124 125 si->offsets = XNEWVEC (int, num_ssa_names); 126 for (i = 0; i < num_ssa_names; ++i) 127 si->offsets[i] = -1; 128 } 129 130 counter_val = gpr_p ? cfun->va_list_gpr_size : cfun->va_list_fpr_size; 131 max_size = gpr_p ? VA_LIST_MAX_GPR_SIZE : VA_LIST_MAX_FPR_SIZE; 132 orig_lhs = lhs = rhs; 133 while (lhs) 134 { 135 enum tree_code rhs_code; 136 tree rhs1; 137 138 if (si->offsets[SSA_NAME_VERSION (lhs)] != -1) 139 { 140 if (counter_val >= max_size) 141 { 142 ret = max_size; 143 break; 144 } 145 146 ret -= counter_val - si->offsets[SSA_NAME_VERSION (lhs)]; 147 break; 148 } 149 150 stmt = SSA_NAME_DEF_STMT (lhs); 151 152 if (!is_gimple_assign (stmt) || gimple_assign_lhs (stmt) != lhs) 153 return (unsigned HOST_WIDE_INT) -1; 154 155 rhs_code = gimple_assign_rhs_code (stmt); 156 rhs1 = gimple_assign_rhs1 (stmt); 157 if ((get_gimple_rhs_class (rhs_code) == GIMPLE_SINGLE_RHS 158 || gimple_assign_cast_p (stmt)) 159 && TREE_CODE (rhs1) == SSA_NAME) 160 { 161 lhs = rhs1; 162 continue; 163 } 164 165 if ((rhs_code == POINTER_PLUS_EXPR 166 || rhs_code == PLUS_EXPR) 167 && TREE_CODE (rhs1) == SSA_NAME 168 && host_integerp (gimple_assign_rhs2 (stmt), 1)) 169 { 170 ret += tree_low_cst (gimple_assign_rhs2 (stmt), 1); 171 lhs = rhs1; 172 continue; 173 } 174 175 if (rhs_code == ADDR_EXPR 176 && TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF 177 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0)) == SSA_NAME 178 && host_integerp (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1), 1)) 179 { 180 ret += tree_low_cst (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1), 1); 181 lhs = TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0); 182 continue; 183 } 184 185 if (get_gimple_rhs_class (rhs_code) != GIMPLE_SINGLE_RHS) 186 return (unsigned HOST_WIDE_INT) -1; 187 188 rhs = gimple_assign_rhs1 (stmt); 189 if (TREE_CODE (counter) != TREE_CODE (rhs)) 190 return (unsigned HOST_WIDE_INT) -1; 191 192 if (TREE_CODE (counter) == COMPONENT_REF) 193 { 194 if (get_base_address (counter) != get_base_address (rhs) 195 || TREE_CODE (TREE_OPERAND (rhs, 1)) != FIELD_DECL 196 || TREE_OPERAND (counter, 1) != TREE_OPERAND (rhs, 1)) 197 return (unsigned HOST_WIDE_INT) -1; 198 } 199 else if (counter != rhs) 200 return (unsigned HOST_WIDE_INT) -1; 201 202 lhs = NULL; 203 } 204 205 lhs = orig_lhs; 206 val = ret + counter_val; 207 while (lhs) 208 { 209 enum tree_code rhs_code; 210 tree rhs1; 211 212 if (si->offsets[SSA_NAME_VERSION (lhs)] != -1) 213 break; 214 215 if (val >= max_size) 216 si->offsets[SSA_NAME_VERSION (lhs)] = max_size; 217 else 218 si->offsets[SSA_NAME_VERSION (lhs)] = val; 219 220 stmt = SSA_NAME_DEF_STMT (lhs); 221 222 rhs_code = gimple_assign_rhs_code (stmt); 223 rhs1 = gimple_assign_rhs1 (stmt); 224 if ((get_gimple_rhs_class (rhs_code) == GIMPLE_SINGLE_RHS 225 || gimple_assign_cast_p (stmt)) 226 && TREE_CODE (rhs1) == SSA_NAME) 227 { 228 lhs = rhs1; 229 continue; 230 } 231 232 if ((rhs_code == POINTER_PLUS_EXPR 233 || rhs_code == PLUS_EXPR) 234 && TREE_CODE (rhs1) == SSA_NAME 235 && host_integerp (gimple_assign_rhs2 (stmt), 1)) 236 { 237 val -= tree_low_cst (gimple_assign_rhs2 (stmt), 1); 238 lhs = rhs1; 239 continue; 240 } 241 242 if (rhs_code == ADDR_EXPR 243 && TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF 244 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0)) == SSA_NAME 245 && host_integerp (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1), 1)) 246 { 247 val -= tree_low_cst (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1), 1); 248 lhs = TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0); 249 continue; 250 } 251 252 lhs = NULL; 253 } 254 255 return ret; 256 } 257 258 259 /* Called by walk_tree to look for references to va_list variables. */ 260 261 static tree 262 find_va_list_reference (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED, 263 void *data) 264 { 265 bitmap va_list_vars = (bitmap) ((struct walk_stmt_info *) data)->info; 266 tree var = *tp; 267 268 if (TREE_CODE (var) == SSA_NAME) 269 var = SSA_NAME_VAR (var); 270 271 if (TREE_CODE (var) == VAR_DECL 272 && bitmap_bit_p (va_list_vars, DECL_UID (var))) 273 return var; 274 275 return NULL_TREE; 276 } 277 278 279 /* Helper function of va_list_counter_struct_op. Compute 280 cfun->va_list_{g,f}pr_size. AP is a va_list GPR/FPR counter, 281 if WRITE_P is true, seen in AP = VAR, otherwise seen in VAR = AP 282 statement. GPR_P is true if AP is a GPR counter, false if it is 283 a FPR counter. */ 284 285 static void 286 va_list_counter_op (struct stdarg_info *si, tree ap, tree var, bool gpr_p, 287 bool write_p) 288 { 289 unsigned HOST_WIDE_INT increment; 290 291 if (si->compute_sizes < 0) 292 { 293 si->compute_sizes = 0; 294 if (si->va_start_count == 1 295 && reachable_at_most_once (si->bb, si->va_start_bb)) 296 si->compute_sizes = 1; 297 298 if (dump_file && (dump_flags & TDF_DETAILS)) 299 fprintf (dump_file, 300 "bb%d will %sbe executed at most once for each va_start " 301 "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ", 302 si->va_start_bb->index); 303 } 304 305 if (write_p 306 && si->compute_sizes 307 && (increment = va_list_counter_bump (si, ap, var, gpr_p)) + 1 > 1) 308 { 309 if (gpr_p && cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE) 310 { 311 cfun->va_list_gpr_size += increment; 312 return; 313 } 314 315 if (!gpr_p && cfun->va_list_fpr_size + increment < VA_LIST_MAX_FPR_SIZE) 316 { 317 cfun->va_list_fpr_size += increment; 318 return; 319 } 320 } 321 322 if (write_p || !si->compute_sizes) 323 { 324 if (gpr_p) 325 cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE; 326 else 327 cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE; 328 } 329 } 330 331 332 /* If AP is a va_list GPR/FPR counter, compute cfun->va_list_{g,f}pr_size. 333 If WRITE_P is true, AP has been seen in AP = VAR assignment, if WRITE_P 334 is false, AP has been seen in VAR = AP assignment. 335 Return true if the AP = VAR (resp. VAR = AP) statement is a recognized 336 va_arg operation that doesn't cause the va_list variable to escape 337 current function. */ 338 339 static bool 340 va_list_counter_struct_op (struct stdarg_info *si, tree ap, tree var, 341 bool write_p) 342 { 343 tree base; 344 345 if (TREE_CODE (ap) != COMPONENT_REF 346 || TREE_CODE (TREE_OPERAND (ap, 1)) != FIELD_DECL) 347 return false; 348 349 if (TREE_CODE (var) != SSA_NAME 350 || bitmap_bit_p (si->va_list_vars, DECL_UID (SSA_NAME_VAR (var)))) 351 return false; 352 353 base = get_base_address (ap); 354 if (TREE_CODE (base) != VAR_DECL 355 || !bitmap_bit_p (si->va_list_vars, DECL_UID (base))) 356 return false; 357 358 if (TREE_OPERAND (ap, 1) == va_list_gpr_counter_field) 359 va_list_counter_op (si, ap, var, true, write_p); 360 else if (TREE_OPERAND (ap, 1) == va_list_fpr_counter_field) 361 va_list_counter_op (si, ap, var, false, write_p); 362 363 return true; 364 } 365 366 367 /* Check for TEM = AP. Return true if found and the caller shouldn't 368 search for va_list references in the statement. */ 369 370 static bool 371 va_list_ptr_read (struct stdarg_info *si, tree ap, tree tem) 372 { 373 if (TREE_CODE (ap) != VAR_DECL 374 || !bitmap_bit_p (si->va_list_vars, DECL_UID (ap))) 375 return false; 376 377 if (TREE_CODE (tem) != SSA_NAME 378 || bitmap_bit_p (si->va_list_vars, 379 DECL_UID (SSA_NAME_VAR (tem))) 380 || is_global_var (SSA_NAME_VAR (tem))) 381 return false; 382 383 if (si->compute_sizes < 0) 384 { 385 si->compute_sizes = 0; 386 if (si->va_start_count == 1 387 && reachable_at_most_once (si->bb, si->va_start_bb)) 388 si->compute_sizes = 1; 389 390 if (dump_file && (dump_flags & TDF_DETAILS)) 391 fprintf (dump_file, 392 "bb%d will %sbe executed at most once for each va_start " 393 "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ", 394 si->va_start_bb->index); 395 } 396 397 /* For void * or char * va_list types, there is just one counter. 398 If va_arg is used in a loop, we don't know how many registers need 399 saving. */ 400 if (! si->compute_sizes) 401 return false; 402 403 if (va_list_counter_bump (si, ap, tem, true) == (unsigned HOST_WIDE_INT) -1) 404 return false; 405 406 /* Note the temporary, as we need to track whether it doesn't escape 407 the current function. */ 408 bitmap_set_bit (si->va_list_escape_vars, 409 DECL_UID (SSA_NAME_VAR (tem))); 410 return true; 411 } 412 413 414 /* Check for: 415 tem1 = AP; 416 TEM2 = tem1 + CST; 417 AP = TEM2; 418 sequence and update cfun->va_list_gpr_size. Return true if found. */ 419 420 static bool 421 va_list_ptr_write (struct stdarg_info *si, tree ap, tree tem2) 422 { 423 unsigned HOST_WIDE_INT increment; 424 425 if (TREE_CODE (ap) != VAR_DECL 426 || !bitmap_bit_p (si->va_list_vars, DECL_UID (ap))) 427 return false; 428 429 if (TREE_CODE (tem2) != SSA_NAME 430 || bitmap_bit_p (si->va_list_vars, DECL_UID (SSA_NAME_VAR (tem2)))) 431 return false; 432 433 if (si->compute_sizes <= 0) 434 return false; 435 436 increment = va_list_counter_bump (si, ap, tem2, true); 437 if (increment + 1 <= 1) 438 return false; 439 440 if (cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE) 441 cfun->va_list_gpr_size += increment; 442 else 443 cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE; 444 445 return true; 446 } 447 448 449 /* If RHS is X, (some type *) X or X + CST for X a temporary variable 450 containing value of some va_list variable plus optionally some constant, 451 either set si->va_list_escapes or add LHS to si->va_list_escape_vars, 452 depending whether LHS is a function local temporary. */ 453 454 static void 455 check_va_list_escapes (struct stdarg_info *si, tree lhs, tree rhs) 456 { 457 if (! POINTER_TYPE_P (TREE_TYPE (rhs))) 458 return; 459 460 if (TREE_CODE (rhs) == SSA_NAME) 461 { 462 if (! bitmap_bit_p (si->va_list_escape_vars, 463 DECL_UID (SSA_NAME_VAR (rhs)))) 464 return; 465 } 466 else if (TREE_CODE (rhs) == ADDR_EXPR 467 && TREE_CODE (TREE_OPERAND (rhs, 0)) == MEM_REF 468 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)) == SSA_NAME) 469 { 470 if (! bitmap_bit_p (si->va_list_escape_vars, 471 DECL_UID (SSA_NAME_VAR (TREE_OPERAND 472 (TREE_OPERAND (rhs, 0), 0))))) 473 return; 474 } 475 else 476 return; 477 478 if (TREE_CODE (lhs) != SSA_NAME || is_global_var (SSA_NAME_VAR (lhs))) 479 { 480 si->va_list_escapes = true; 481 return; 482 } 483 484 if (si->compute_sizes < 0) 485 { 486 si->compute_sizes = 0; 487 if (si->va_start_count == 1 488 && reachable_at_most_once (si->bb, si->va_start_bb)) 489 si->compute_sizes = 1; 490 491 if (dump_file && (dump_flags & TDF_DETAILS)) 492 fprintf (dump_file, 493 "bb%d will %sbe executed at most once for each va_start " 494 "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ", 495 si->va_start_bb->index); 496 } 497 498 /* For void * or char * va_list types, there is just one counter. 499 If va_arg is used in a loop, we don't know how many registers need 500 saving. */ 501 if (! si->compute_sizes) 502 { 503 si->va_list_escapes = true; 504 return; 505 } 506 507 if (va_list_counter_bump (si, si->va_start_ap, lhs, true) 508 == (unsigned HOST_WIDE_INT) -1) 509 { 510 si->va_list_escapes = true; 511 return; 512 } 513 514 bitmap_set_bit (si->va_list_escape_vars, 515 DECL_UID (SSA_NAME_VAR (lhs))); 516 } 517 518 519 /* Check all uses of temporaries from si->va_list_escape_vars bitmap. 520 Return true if va_list might be escaping. */ 521 522 static bool 523 check_all_va_list_escapes (struct stdarg_info *si) 524 { 525 basic_block bb; 526 527 FOR_EACH_BB (bb) 528 { 529 gimple_stmt_iterator i; 530 531 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i)) 532 { 533 gimple stmt = gsi_stmt (i); 534 tree use; 535 ssa_op_iter iter; 536 537 if (is_gimple_debug (stmt)) 538 continue; 539 540 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES) 541 { 542 if (! bitmap_bit_p (si->va_list_escape_vars, 543 DECL_UID (SSA_NAME_VAR (use)))) 544 continue; 545 546 if (is_gimple_assign (stmt)) 547 { 548 tree rhs = gimple_assign_rhs1 (stmt); 549 enum tree_code rhs_code = gimple_assign_rhs_code (stmt); 550 551 /* x = *ap_temp; */ 552 if (rhs_code == MEM_REF 553 && TREE_OPERAND (rhs, 0) == use 554 && TYPE_SIZE_UNIT (TREE_TYPE (rhs)) 555 && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (rhs)), 1) 556 && si->offsets[SSA_NAME_VERSION (use)] != -1) 557 { 558 unsigned HOST_WIDE_INT gpr_size; 559 tree access_size = TYPE_SIZE_UNIT (TREE_TYPE (rhs)); 560 561 gpr_size = si->offsets[SSA_NAME_VERSION (use)] 562 + tree_low_cst (TREE_OPERAND (rhs, 1), 0) 563 + tree_low_cst (access_size, 1); 564 if (gpr_size >= VA_LIST_MAX_GPR_SIZE) 565 cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE; 566 else if (gpr_size > cfun->va_list_gpr_size) 567 cfun->va_list_gpr_size = gpr_size; 568 continue; 569 } 570 571 /* va_arg sequences may contain 572 other_ap_temp = ap_temp; 573 other_ap_temp = ap_temp + constant; 574 other_ap_temp = (some_type *) ap_temp; 575 ap = ap_temp; 576 statements. */ 577 if (rhs == use 578 && ((rhs_code == POINTER_PLUS_EXPR 579 && (TREE_CODE (gimple_assign_rhs2 (stmt)) 580 == INTEGER_CST)) 581 || gimple_assign_cast_p (stmt) 582 || (get_gimple_rhs_class (rhs_code) 583 == GIMPLE_SINGLE_RHS))) 584 { 585 tree lhs = gimple_assign_lhs (stmt); 586 587 if (TREE_CODE (lhs) == SSA_NAME 588 && bitmap_bit_p (si->va_list_escape_vars, 589 DECL_UID (SSA_NAME_VAR (lhs)))) 590 continue; 591 592 if (TREE_CODE (lhs) == VAR_DECL 593 && bitmap_bit_p (si->va_list_vars, 594 DECL_UID (lhs))) 595 continue; 596 } 597 else if (rhs_code == ADDR_EXPR 598 && TREE_CODE (TREE_OPERAND (rhs, 0)) == MEM_REF 599 && TREE_OPERAND (TREE_OPERAND (rhs, 0), 0) == use) 600 { 601 tree lhs = gimple_assign_lhs (stmt); 602 603 if (bitmap_bit_p (si->va_list_escape_vars, 604 DECL_UID (SSA_NAME_VAR (lhs)))) 605 continue; 606 } 607 } 608 609 if (dump_file && (dump_flags & TDF_DETAILS)) 610 { 611 fputs ("va_list escapes in ", dump_file); 612 print_gimple_stmt (dump_file, stmt, 0, dump_flags); 613 fputc ('\n', dump_file); 614 } 615 return true; 616 } 617 } 618 } 619 620 return false; 621 } 622 623 624 /* Return true if this optimization pass should be done. 625 It makes only sense for stdarg functions. */ 626 627 static bool 628 gate_optimize_stdarg (void) 629 { 630 /* This optimization is only for stdarg functions. */ 631 return cfun->stdarg != 0; 632 } 633 634 635 /* Entry point to the stdarg optimization pass. */ 636 637 static unsigned int 638 execute_optimize_stdarg (void) 639 { 640 basic_block bb; 641 bool va_list_escapes = false; 642 bool va_list_simple_ptr; 643 struct stdarg_info si; 644 struct walk_stmt_info wi; 645 const char *funcname = NULL; 646 tree cfun_va_list; 647 648 cfun->va_list_gpr_size = 0; 649 cfun->va_list_fpr_size = 0; 650 memset (&si, 0, sizeof (si)); 651 si.va_list_vars = BITMAP_ALLOC (NULL); 652 si.va_list_escape_vars = BITMAP_ALLOC (NULL); 653 654 if (dump_file) 655 funcname = lang_hooks.decl_printable_name (current_function_decl, 2); 656 657 cfun_va_list = targetm.fn_abi_va_list (cfun->decl); 658 va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list) 659 && (TREE_TYPE (cfun_va_list) == void_type_node 660 || TREE_TYPE (cfun_va_list) == char_type_node); 661 gcc_assert (is_gimple_reg_type (cfun_va_list) == va_list_simple_ptr); 662 663 FOR_EACH_BB (bb) 664 { 665 gimple_stmt_iterator i; 666 667 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i)) 668 { 669 gimple stmt = gsi_stmt (i); 670 tree callee, ap; 671 672 if (!is_gimple_call (stmt)) 673 continue; 674 675 callee = gimple_call_fndecl (stmt); 676 if (!callee 677 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) 678 continue; 679 680 switch (DECL_FUNCTION_CODE (callee)) 681 { 682 case BUILT_IN_VA_START: 683 break; 684 /* If old style builtins are used, don't optimize anything. */ 685 case BUILT_IN_SAVEREGS: 686 case BUILT_IN_NEXT_ARG: 687 va_list_escapes = true; 688 continue; 689 default: 690 continue; 691 } 692 693 si.va_start_count++; 694 ap = gimple_call_arg (stmt, 0); 695 696 if (TREE_CODE (ap) != ADDR_EXPR) 697 { 698 va_list_escapes = true; 699 break; 700 } 701 ap = TREE_OPERAND (ap, 0); 702 if (TREE_CODE (ap) == ARRAY_REF) 703 { 704 if (! integer_zerop (TREE_OPERAND (ap, 1))) 705 { 706 va_list_escapes = true; 707 break; 708 } 709 ap = TREE_OPERAND (ap, 0); 710 } 711 if (TYPE_MAIN_VARIANT (TREE_TYPE (ap)) 712 != TYPE_MAIN_VARIANT (targetm.fn_abi_va_list (cfun->decl)) 713 || TREE_CODE (ap) != VAR_DECL) 714 { 715 va_list_escapes = true; 716 break; 717 } 718 719 if (is_global_var (ap)) 720 { 721 va_list_escapes = true; 722 break; 723 } 724 725 bitmap_set_bit (si.va_list_vars, DECL_UID (ap)); 726 727 /* VA_START_BB and VA_START_AP will be only used if there is just 728 one va_start in the function. */ 729 si.va_start_bb = bb; 730 si.va_start_ap = ap; 731 } 732 733 if (va_list_escapes) 734 break; 735 } 736 737 /* If there were no va_start uses in the function, there is no need to 738 save anything. */ 739 if (si.va_start_count == 0) 740 goto finish; 741 742 /* If some va_list arguments weren't local, we can't optimize. */ 743 if (va_list_escapes) 744 goto finish; 745 746 /* For void * or char * va_list, something useful can be done only 747 if there is just one va_start. */ 748 if (va_list_simple_ptr && si.va_start_count > 1) 749 { 750 va_list_escapes = true; 751 goto finish; 752 } 753 754 /* For struct * va_list, if the backend didn't tell us what the counter fields 755 are, there is nothing more we can do. */ 756 if (!va_list_simple_ptr 757 && va_list_gpr_counter_field == NULL_TREE 758 && va_list_fpr_counter_field == NULL_TREE) 759 { 760 va_list_escapes = true; 761 goto finish; 762 } 763 764 /* For void * or char * va_list there is just one counter 765 (va_list itself). Use VA_LIST_GPR_SIZE for it. */ 766 if (va_list_simple_ptr) 767 cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE; 768 769 calculate_dominance_info (CDI_DOMINATORS); 770 memset (&wi, 0, sizeof (wi)); 771 wi.info = si.va_list_vars; 772 773 FOR_EACH_BB (bb) 774 { 775 gimple_stmt_iterator i; 776 777 si.compute_sizes = -1; 778 si.bb = bb; 779 780 /* For va_list_simple_ptr, we have to check PHI nodes too. We treat 781 them as assignments for the purpose of escape analysis. This is 782 not needed for non-simple va_list because virtual phis don't perform 783 any real data movement. */ 784 if (va_list_simple_ptr) 785 { 786 tree lhs, rhs; 787 use_operand_p uop; 788 ssa_op_iter soi; 789 790 for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i)) 791 { 792 gimple phi = gsi_stmt (i); 793 lhs = PHI_RESULT (phi); 794 795 if (!is_gimple_reg (lhs)) 796 continue; 797 798 FOR_EACH_PHI_ARG (uop, phi, soi, SSA_OP_USE) 799 { 800 rhs = USE_FROM_PTR (uop); 801 if (va_list_ptr_read (&si, rhs, lhs)) 802 continue; 803 else if (va_list_ptr_write (&si, lhs, rhs)) 804 continue; 805 else 806 check_va_list_escapes (&si, lhs, rhs); 807 808 if (si.va_list_escapes) 809 { 810 if (dump_file && (dump_flags & TDF_DETAILS)) 811 { 812 fputs ("va_list escapes in ", dump_file); 813 print_gimple_stmt (dump_file, phi, 0, dump_flags); 814 fputc ('\n', dump_file); 815 } 816 va_list_escapes = true; 817 } 818 } 819 } 820 } 821 822 for (i = gsi_start_bb (bb); 823 !gsi_end_p (i) && !va_list_escapes; 824 gsi_next (&i)) 825 { 826 gimple stmt = gsi_stmt (i); 827 828 /* Don't look at __builtin_va_{start,end}, they are ok. */ 829 if (is_gimple_call (stmt)) 830 { 831 tree callee = gimple_call_fndecl (stmt); 832 833 if (callee 834 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL 835 && (DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_START 836 || DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_END)) 837 continue; 838 } 839 840 if (is_gimple_assign (stmt)) 841 { 842 tree lhs = gimple_assign_lhs (stmt); 843 tree rhs = gimple_assign_rhs1 (stmt); 844 845 if (va_list_simple_ptr) 846 { 847 if (get_gimple_rhs_class (gimple_assign_rhs_code (stmt)) 848 == GIMPLE_SINGLE_RHS) 849 { 850 /* Check for ap ={v} {}. */ 851 if (TREE_CLOBBER_P (rhs)) 852 continue; 853 854 /* Check for tem = ap. */ 855 else if (va_list_ptr_read (&si, rhs, lhs)) 856 continue; 857 858 /* Check for the last insn in: 859 tem1 = ap; 860 tem2 = tem1 + CST; 861 ap = tem2; 862 sequence. */ 863 else if (va_list_ptr_write (&si, lhs, rhs)) 864 continue; 865 } 866 867 if ((gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR 868 && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST) 869 || CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt)) 870 || (get_gimple_rhs_class (gimple_assign_rhs_code (stmt)) 871 == GIMPLE_SINGLE_RHS)) 872 check_va_list_escapes (&si, lhs, rhs); 873 } 874 else 875 { 876 if (get_gimple_rhs_class (gimple_assign_rhs_code (stmt)) 877 == GIMPLE_SINGLE_RHS) 878 { 879 /* Check for ap ={v} {}. */ 880 if (TREE_CLOBBER_P (rhs)) 881 continue; 882 883 /* Check for ap[0].field = temp. */ 884 else if (va_list_counter_struct_op (&si, lhs, rhs, true)) 885 continue; 886 887 /* Check for temp = ap[0].field. */ 888 else if (va_list_counter_struct_op (&si, rhs, lhs, 889 false)) 890 continue; 891 } 892 893 /* Do any architecture specific checking. */ 894 if (targetm.stdarg_optimize_hook 895 && targetm.stdarg_optimize_hook (&si, stmt)) 896 continue; 897 } 898 } 899 else if (is_gimple_debug (stmt)) 900 continue; 901 902 /* All other uses of va_list are either va_copy (that is not handled 903 in this optimization), taking address of va_list variable or 904 passing va_list to other functions (in that case va_list might 905 escape the function and therefore va_start needs to set it up 906 fully), or some unexpected use of va_list. None of these should 907 happen in a gimplified VA_ARG_EXPR. */ 908 if (si.va_list_escapes 909 || walk_gimple_op (stmt, find_va_list_reference, &wi)) 910 { 911 if (dump_file && (dump_flags & TDF_DETAILS)) 912 { 913 fputs ("va_list escapes in ", dump_file); 914 print_gimple_stmt (dump_file, stmt, 0, dump_flags); 915 fputc ('\n', dump_file); 916 } 917 va_list_escapes = true; 918 } 919 } 920 921 if (va_list_escapes) 922 break; 923 } 924 925 if (! va_list_escapes 926 && va_list_simple_ptr 927 && ! bitmap_empty_p (si.va_list_escape_vars) 928 && check_all_va_list_escapes (&si)) 929 va_list_escapes = true; 930 931 finish: 932 if (va_list_escapes) 933 { 934 cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE; 935 cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE; 936 } 937 BITMAP_FREE (si.va_list_vars); 938 BITMAP_FREE (si.va_list_escape_vars); 939 free (si.offsets); 940 if (dump_file) 941 { 942 fprintf (dump_file, "%s: va_list escapes %d, needs to save ", 943 funcname, (int) va_list_escapes); 944 if (cfun->va_list_gpr_size >= VA_LIST_MAX_GPR_SIZE) 945 fputs ("all", dump_file); 946 else 947 fprintf (dump_file, "%d", cfun->va_list_gpr_size); 948 fputs (" GPR units and ", dump_file); 949 if (cfun->va_list_fpr_size >= VA_LIST_MAX_FPR_SIZE) 950 fputs ("all", dump_file); 951 else 952 fprintf (dump_file, "%d", cfun->va_list_fpr_size); 953 fputs (" FPR units.\n", dump_file); 954 } 955 return 0; 956 } 957 958 959 struct gimple_opt_pass pass_stdarg = 960 { 961 { 962 GIMPLE_PASS, 963 "stdarg", /* name */ 964 gate_optimize_stdarg, /* gate */ 965 execute_optimize_stdarg, /* execute */ 966 NULL, /* sub */ 967 NULL, /* next */ 968 0, /* static_pass_number */ 969 TV_NONE, /* tv_id */ 970 PROP_cfg | PROP_ssa, /* properties_required */ 971 0, /* properties_provided */ 972 0, /* properties_destroyed */ 973 0, /* todo_flags_start */ 974 0 /* todo_flags_finish */ 975 } 976 }; 977