gcc/tree-stdarg.c

   1 /* Pass computing data for optimizing stdarg functions.
   2    Copyright (C) 2004-2015 Free Software Foundation, Inc.
   3    Contributed by Jakub Jelinek <jakub@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "hash-set.h"
  26 #include "machmode.h"
  27 #include "vec.h"
  28 #include "double-int.h"
  29 #include "input.h"
  30 #include "alias.h"
  31 #include "symtab.h"
  32 #include "wide-int.h"
  33 #include "inchash.h"
  34 #include "tree.h"
  35 #include "fold-const.h"
  36 #include "hard-reg-set.h"
  37 #include "input.h"
  38 #include "function.h"
  39 #include "langhooks.h"
  40 #include "gimple-pretty-print.h"
  41 #include "target.h"
  42 #include "bitmap.h"
  43 #include "predict.h"
  44 #include "dominance.h"
  45 #include "cfg.h"
  46 #include "basic-block.h"
  47 #include "tree-ssa-alias.h"
  48 #include "internal-fn.h"
  49 #include "gimple-expr.h"
  50 #include "is-a.h"
  51 #include "gimple.h"
  52 #include "gimple-iterator.h"
  53 #include "gimple-walk.h"
  54 #include "gimple-ssa.h"
  55 #include "tree-phinodes.h"
  56 #include "ssa-iterators.h"
  57 #include "stringpool.h"
  58 #include "tree-ssanames.h"
  59 #include "sbitmap.h"
  60 #include "tree-pass.h"
  61 #include "tree-stdarg.h"
  62
  63 /* A simple pass that attempts to optimize stdarg functions on architectures
  64    that need to save register arguments to stack on entry to stdarg functions.
  65    If the function doesn't use any va_start macros, no registers need to
  66    be saved.  If va_start macros are used, the va_list variables don't escape
  67    the function, it is only necessary to save registers that will be used
  68    in va_arg macros.  E.g. if va_arg is only used with integral types
  69    in the function, floating point registers don't need to be saved, etc.  */
  70
  71
  72 /* Return true if basic block VA_ARG_BB is dominated by VA_START_BB and
  73    is executed at most as many times as VA_START_BB.  */
  74
  75 static bool
  76 reachable_at_most_once (basic_block va_arg_bb, basic_block va_start_bb)
  77 {
  78   vec<edge> stack = vNULL;
  79   edge e;
  80   edge_iterator ei;
  81   sbitmap visited;
  82   bool ret;
  83
  84   if (va_arg_bb == va_start_bb)
  85     return true;
  86
  87   if (! dominated_by_p (CDI_DOMINATORS, va_arg_bb, va_start_bb))
  88     return false;
  89
  90   visited = sbitmap_alloc (last_basic_block_for_fn (cfun));
  91   bitmap_clear (visited);
  92   ret = true;
  93
  94   FOR_EACH_EDGE (e, ei, va_arg_bb->preds)
  95     stack.safe_push (e);
  96
  97   while (! stack.is_empty ())
  98     {
  99       basic_block src;
 100
 101       e = stack.pop ();
 102       src = e->src;
 103
 104       if (e->flags & EDGE_COMPLEX)
 105         {
 106           ret = false;
 107           break;
 108         }
 109
 110       if (src == va_start_bb)
 111         continue;
 112
 113       /* va_arg_bb can be executed more times than va_start_bb.  */
 114       if (src == va_arg_bb)
 115         {
 116           ret = false;
 117           break;
 118         }
 119
 120       gcc_assert (src != ENTRY_BLOCK_PTR_FOR_FN (cfun));
 121
 122       if (! bitmap_bit_p (visited, src->index))
 123         {
 124           bitmap_set_bit (visited, src->index);
 125           FOR_EACH_EDGE (e, ei, src->preds)
 126             stack.safe_push (e);
 127         }
 128     }
 129
 130   stack.release ();
 131   sbitmap_free (visited);
 132   return ret;
 133 }
 134
 135
 136 /* For statement COUNTER = RHS, if RHS is COUNTER + constant,
 137    return constant, otherwise return HOST_WIDE_INT_M1U.
 138    GPR_P is true if this is GPR counter.  */
 139
 140 static unsigned HOST_WIDE_INT
 141 va_list_counter_bump (struct stdarg_info *si, tree counter, tree rhs,
 142                       bool gpr_p)
 143 {
 144   tree lhs, orig_lhs;
 145   gimple stmt;
 146   unsigned HOST_WIDE_INT ret = 0, val, counter_val;
 147   unsigned int max_size;
 148
 149   if (si->offsets == NULL)
 150     {
 151       unsigned int i;
 152
 153       si->offsets = XNEWVEC (int, num_ssa_names);
 154       for (i = 0; i < num_ssa_names; ++i)
 155         si->offsets[i] = -1;
 156     }
 157
 158   counter_val = gpr_p ? cfun->va_list_gpr_size : cfun->va_list_fpr_size;
 159   max_size = gpr_p ? VA_LIST_MAX_GPR_SIZE : VA_LIST_MAX_FPR_SIZE;
 160   orig_lhs = lhs = rhs;
 161   while (lhs)
 162     {
 163       enum tree_code rhs_code;
 164       tree rhs1;
 165
 166       if (si->offsets[SSA_NAME_VERSION (lhs)] != -1)
 167         {
 168           if (counter_val >= max_size)
 169             {
 170               ret = max_size;
 171               break;
 172             }
 173
 174           ret -= counter_val - si->offsets[SSA_NAME_VERSION (lhs)];
 175           break;
 176         }
 177
 178       stmt = SSA_NAME_DEF_STMT (lhs);
 179
 180       if (!is_gimple_assign (stmt) || gimple_assign_lhs (stmt) != lhs)
 181         return HOST_WIDE_INT_M1U;
 182
 183       rhs_code = gimple_assign_rhs_code (stmt);
 184       rhs1 = gimple_assign_rhs1 (stmt);
 185       if ((get_gimple_rhs_class (rhs_code) == GIMPLE_SINGLE_RHS
 186            || gimple_assign_cast_p (stmt))
 187           && TREE_CODE (rhs1) == SSA_NAME)
 188         {
 189           lhs = rhs1;
 190           continue;
 191         }
 192
 193       if ((rhs_code == POINTER_PLUS_EXPR
 194            || rhs_code == PLUS_EXPR)
 195           && TREE_CODE (rhs1) == SSA_NAME
 196           && tree_fits_uhwi_p (gimple_assign_rhs2 (stmt)))
 197         {
 198           ret += tree_to_uhwi (gimple_assign_rhs2 (stmt));
 199           lhs = rhs1;
 200           continue;
 201         }
 202
 203       if (rhs_code == ADDR_EXPR
 204           && TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF
 205           && TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0)) == SSA_NAME
 206           && tree_fits_uhwi_p (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1)))
 207         {
 208           ret += tree_to_uhwi (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1));
 209           lhs = TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0);
 210           continue;
 211         }
 212
 213       if (get_gimple_rhs_class (rhs_code) != GIMPLE_SINGLE_RHS)
 214         return HOST_WIDE_INT_M1U;
 215
 216       rhs = gimple_assign_rhs1 (stmt);
 217       if (TREE_CODE (counter) != TREE_CODE (rhs))
 218         return HOST_WIDE_INT_M1U;
 219
 220       if (TREE_CODE (counter) == COMPONENT_REF)
 221         {
 222           if (get_base_address (counter) != get_base_address (rhs)
 223               || TREE_CODE (TREE_OPERAND (rhs, 1)) != FIELD_DECL
 224               || TREE_OPERAND (counter, 1) != TREE_OPERAND (rhs, 1))
 225             return HOST_WIDE_INT_M1U;
 226         }
 227       else if (counter != rhs)
 228         return HOST_WIDE_INT_M1U;
 229
 230       lhs = NULL;
 231     }
 232
 233   lhs = orig_lhs;
 234   val = ret + counter_val;
 235   while (lhs)
 236     {
 237       enum tree_code rhs_code;
 238       tree rhs1;
 239
 240       if (si->offsets[SSA_NAME_VERSION (lhs)] != -1)
 241         break;
 242
 243       if (val >= max_size)
 244         si->offsets[SSA_NAME_VERSION (lhs)] = max_size;
 245       else
 246         si->offsets[SSA_NAME_VERSION (lhs)] = val;
 247
 248       stmt = SSA_NAME_DEF_STMT (lhs);
 249
 250       rhs_code = gimple_assign_rhs_code (stmt);
 251       rhs1 = gimple_assign_rhs1 (stmt);
 252       if ((get_gimple_rhs_class (rhs_code) == GIMPLE_SINGLE_RHS
 253            || gimple_assign_cast_p (stmt))
 254           && TREE_CODE (rhs1) == SSA_NAME)
 255         {
 256           lhs = rhs1;
 257           continue;
 258         }
 259
 260       if ((rhs_code == POINTER_PLUS_EXPR
 261            || rhs_code == PLUS_EXPR)
 262           && TREE_CODE (rhs1) == SSA_NAME
 263           && tree_fits_uhwi_p (gimple_assign_rhs2 (stmt)))
 264         {
 265           val -= tree_to_uhwi (gimple_assign_rhs2 (stmt));
 266           lhs = rhs1;
 267           continue;
 268         }
 269
 270       if (rhs_code == ADDR_EXPR
 271           && TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF
 272           && TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0)) == SSA_NAME
 273           && tree_fits_uhwi_p (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1)))
 274         {
 275           val -= tree_to_uhwi (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1));
 276           lhs = TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0);
 277           continue;
 278         }
 279
 280       lhs = NULL;
 281     }
 282
 283   return ret;
 284 }
 285
 286
 287 /* Called by walk_tree to look for references to va_list variables.  */
 288
 289 static tree
 290 find_va_list_reference (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
 291                         void *data)
 292 {
 293   bitmap va_list_vars = (bitmap) ((struct walk_stmt_info *) data)->info;
 294   tree var = *tp;
 295
 296   if (TREE_CODE (var) == SSA_NAME)
 297     {
 298       if (bitmap_bit_p (va_list_vars, SSA_NAME_VERSION (var)))
 299         return var;
 300     }
 301   else if (TREE_CODE (var) == VAR_DECL)
 302     {
 303       if (bitmap_bit_p (va_list_vars, DECL_UID (var) + num_ssa_names))
 304         return var;
 305     }
 306
 307   return NULL_TREE;
 308 }
 309
 310
 311 /* Helper function of va_list_counter_struct_op.  Compute
 312    cfun->va_list_{g,f}pr_size.  AP is a va_list GPR/FPR counter,
 313    if WRITE_P is true, seen in AP = VAR, otherwise seen in VAR = AP
 314    statement.  GPR_P is true if AP is a GPR counter, false if it is
 315    a FPR counter.  */
 316
 317 static void
 318 va_list_counter_op (struct stdarg_info *si, tree ap, tree var, bool gpr_p,
 319                     bool write_p)
 320 {
 321   unsigned HOST_WIDE_INT increment;
 322
 323   if (si->compute_sizes < 0)
 324     {
 325       si->compute_sizes = 0;
 326       if (si->va_start_count == 1
 327           && reachable_at_most_once (si->bb, si->va_start_bb))
 328         si->compute_sizes = 1;
 329
 330       if (dump_file && (dump_flags & TDF_DETAILS))
 331         fprintf (dump_file,
 332                  "bb%d will %sbe executed at most once for each va_start "
 333                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 334                  si->va_start_bb->index);
 335     }
 336
 337   if (write_p
 338       && si->compute_sizes
 339       && (increment = va_list_counter_bump (si, ap, var, gpr_p)) + 1 > 1)
 340     {
 341       if (gpr_p && cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE)
 342         {
 343           cfun->va_list_gpr_size += increment;
 344           return;
 345         }
 346
 347       if (!gpr_p && cfun->va_list_fpr_size + increment < VA_LIST_MAX_FPR_SIZE)
 348         {
 349           cfun->va_list_fpr_size += increment;
 350           return;
 351         }
 352     }
 353
 354   if (write_p || !si->compute_sizes)
 355     {
 356       if (gpr_p)
 357         cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 358       else
 359         cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
 360     }
 361 }
 362
 363
 364 /* If AP is a va_list GPR/FPR counter, compute cfun->va_list_{g,f}pr_size.
 365    If WRITE_P is true, AP has been seen in AP = VAR assignment, if WRITE_P
 366    is false, AP has been seen in VAR = AP assignment.
 367    Return true if the AP = VAR (resp. VAR = AP) statement is a recognized
 368    va_arg operation that doesn't cause the va_list variable to escape
 369    current function.  */
 370
 371 static bool
 372 va_list_counter_struct_op (struct stdarg_info *si, tree ap, tree var,
 373                            bool write_p)
 374 {
 375   tree base;
 376
 377   if (TREE_CODE (ap) != COMPONENT_REF
 378       || TREE_CODE (TREE_OPERAND (ap, 1)) != FIELD_DECL)
 379     return false;
 380
 381   if (TREE_CODE (var) != SSA_NAME
 382       || bitmap_bit_p (si->va_list_vars, SSA_NAME_VERSION (var)))
 383     return false;
 384
 385   base = get_base_address (ap);
 386   if (TREE_CODE (base) != VAR_DECL
 387       || !bitmap_bit_p (si->va_list_vars, DECL_UID (base) + num_ssa_names))
 388     return false;
 389
 390   if (TREE_OPERAND (ap, 1) == va_list_gpr_counter_field)
 391     va_list_counter_op (si, ap, var, true, write_p);
 392   else if (TREE_OPERAND (ap, 1) == va_list_fpr_counter_field)
 393     va_list_counter_op (si, ap, var, false, write_p);
 394
 395   return true;
 396 }
 397
 398
 399 /* Check for TEM = AP.  Return true if found and the caller shouldn't
 400    search for va_list references in the statement.  */
 401
 402 static bool
 403 va_list_ptr_read (struct stdarg_info *si, tree ap, tree tem)
 404 {
 405   if (TREE_CODE (ap) != VAR_DECL
 406       || !bitmap_bit_p (si->va_list_vars, DECL_UID (ap) + num_ssa_names))
 407     return false;
 408
 409   if (TREE_CODE (tem) != SSA_NAME
 410       || bitmap_bit_p (si->va_list_vars, SSA_NAME_VERSION (tem)))
 411     return false;
 412
 413   if (si->compute_sizes < 0)
 414     {
 415       si->compute_sizes = 0;
 416       if (si->va_start_count == 1
 417           && reachable_at_most_once (si->bb, si->va_start_bb))
 418         si->compute_sizes = 1;
 419
 420       if (dump_file && (dump_flags & TDF_DETAILS))
 421         fprintf (dump_file,
 422                  "bb%d will %sbe executed at most once for each va_start "
 423                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 424                  si->va_start_bb->index);
 425     }
 426
 427   /* For void * or char * va_list types, there is just one counter.
 428      If va_arg is used in a loop, we don't know how many registers need
 429      saving.  */
 430   if (! si->compute_sizes)
 431     return false;
 432
 433   if (va_list_counter_bump (si, ap, tem, true) == HOST_WIDE_INT_M1U)
 434     return false;
 435
 436   /* Note the temporary, as we need to track whether it doesn't escape
 437      the current function.  */
 438   bitmap_set_bit (si->va_list_escape_vars, SSA_NAME_VERSION (tem));
 439
 440   return true;
 441 }
 442
 443
 444 /* Check for:
 445      tem1 = AP;
 446      TEM2 = tem1 + CST;
 447      AP = TEM2;
 448    sequence and update cfun->va_list_gpr_size.  Return true if found.  */
 449
 450 static bool
 451 va_list_ptr_write (struct stdarg_info *si, tree ap, tree tem2)
 452 {
 453   unsigned HOST_WIDE_INT increment;
 454
 455   if (TREE_CODE (ap) != VAR_DECL
 456       || !bitmap_bit_p (si->va_list_vars, DECL_UID (ap) + num_ssa_names))
 457     return false;
 458
 459   if (TREE_CODE (tem2) != SSA_NAME
 460       || bitmap_bit_p (si->va_list_vars, SSA_NAME_VERSION (tem2)))
 461     return false;
 462
 463   if (si->compute_sizes <= 0)
 464     return false;
 465
 466   increment = va_list_counter_bump (si, ap, tem2, true);
 467   if (increment + 1 <= 1)
 468     return false;
 469
 470   if (cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE)
 471     cfun->va_list_gpr_size += increment;
 472   else
 473     cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 474
 475   return true;
 476 }
 477
 478
 479 /* If RHS is X, (some type *) X or X + CST for X a temporary variable
 480    containing value of some va_list variable plus optionally some constant,
 481    either set si->va_list_escapes or add LHS to si->va_list_escape_vars,
 482    depending whether LHS is a function local temporary.  */
 483
 484 static void
 485 check_va_list_escapes (struct stdarg_info *si, tree lhs, tree rhs)
 486 {
 487   if (! POINTER_TYPE_P (TREE_TYPE (rhs)))
 488     return;
 489
 490   if (TREE_CODE (rhs) == SSA_NAME)
 491     {
 492       if (! bitmap_bit_p (si->va_list_escape_vars, SSA_NAME_VERSION (rhs)))
 493         return;
 494     }
 495   else if (TREE_CODE (rhs) == ADDR_EXPR
 496            && TREE_CODE (TREE_OPERAND (rhs, 0)) == MEM_REF
 497            && TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)) == SSA_NAME)
 498     {
 499       tree ptr = TREE_OPERAND (TREE_OPERAND (rhs, 0), 0);
 500       if (! bitmap_bit_p (si->va_list_escape_vars, SSA_NAME_VERSION (ptr)))
 501         return;
 502     }
 503   else
 504     return;
 505
 506   if (TREE_CODE (lhs) != SSA_NAME)
 507     {
 508       si->va_list_escapes = true;
 509       return;
 510     }
 511
 512   if (si->compute_sizes < 0)
 513     {
 514       si->compute_sizes = 0;
 515       if (si->va_start_count == 1
 516           && reachable_at_most_once (si->bb, si->va_start_bb))
 517         si->compute_sizes = 1;
 518
 519       if (dump_file && (dump_flags & TDF_DETAILS))
 520         fprintf (dump_file,
 521                  "bb%d will %sbe executed at most once for each va_start "
 522                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 523                  si->va_start_bb->index);
 524     }
 525
 526   /* For void * or char * va_list types, there is just one counter.
 527      If va_arg is used in a loop, we don't know how many registers need
 528      saving.  */
 529   if (! si->compute_sizes)
 530     {
 531       si->va_list_escapes = true;
 532       return;
 533     }
 534
 535   if (va_list_counter_bump (si, si->va_start_ap, lhs, true)
 536       == HOST_WIDE_INT_M1U)
 537     {
 538       si->va_list_escapes = true;
 539       return;
 540     }
 541
 542   bitmap_set_bit (si->va_list_escape_vars, SSA_NAME_VERSION (lhs));
 543 }
 544
 545
 546 /* Check all uses of temporaries from si->va_list_escape_vars bitmap.
 547    Return true if va_list might be escaping.  */
 548
 549 static bool
 550 check_all_va_list_escapes (struct stdarg_info *si)
 551 {
 552   basic_block bb;
 553
 554   FOR_EACH_BB_FN (bb, cfun)
 555     {
 556       for (gphi_iterator i = gsi_start_phis (bb); !gsi_end_p (i);
 557            gsi_next (&i))
 558         {
 559           tree lhs;
 560           use_operand_p uop;
 561           ssa_op_iter soi;
 562           gphi *phi = i.phi ();
 563
 564           lhs = PHI_RESULT (phi);
 565           if (virtual_operand_p (lhs)
 566               || bitmap_bit_p (si->va_list_escape_vars,
 567                                SSA_NAME_VERSION (lhs)))
 568             continue;
 569
 570           FOR_EACH_PHI_ARG (uop, phi, soi, SSA_OP_USE)
 571             {
 572               tree rhs = USE_FROM_PTR (uop);
 573               if (TREE_CODE (rhs) == SSA_NAME
 574                   && bitmap_bit_p (si->va_list_escape_vars,
 575                                 SSA_NAME_VERSION (rhs)))
 576                 {
 577                   if (dump_file && (dump_flags & TDF_DETAILS))
 578                     {
 579                       fputs ("va_list escapes in ", dump_file);
 580                       print_gimple_stmt (dump_file, phi, 0, dump_flags);
 581                       fputc ('\n', dump_file);
 582                     }
 583                   return true;
 584                 }
 585             }
 586         }
 587
 588       for (gimple_stmt_iterator i = gsi_start_bb (bb); !gsi_end_p (i);
 589            gsi_next (&i))
 590         {
 591           gimple stmt = gsi_stmt (i);
 592           tree use;
 593           ssa_op_iter iter;
 594
 595           if (is_gimple_debug (stmt))
 596             continue;
 597
 598           FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES)
 599             {
 600               if (! bitmap_bit_p (si->va_list_escape_vars,
 601                                   SSA_NAME_VERSION (use)))
 602                 continue;
 603
 604               if (is_gimple_assign (stmt))
 605                 {
 606                   tree rhs = gimple_assign_rhs1 (stmt);
 607                   enum tree_code rhs_code = gimple_assign_rhs_code (stmt);
 608
 609                   /* x = *ap_temp;  */
 610                   if (rhs_code == MEM_REF
 611                       && TREE_OPERAND (rhs, 0) == use
 612                       && TYPE_SIZE_UNIT (TREE_TYPE (rhs))
 613                       && tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (rhs)))
 614                       && si->offsets[SSA_NAME_VERSION (use)] != -1)
 615                     {
 616                       unsigned HOST_WIDE_INT gpr_size;
 617                       tree access_size = TYPE_SIZE_UNIT (TREE_TYPE (rhs));
 618
 619                       gpr_size = si->offsets[SSA_NAME_VERSION (use)]
 620                                  + tree_to_shwi (TREE_OPERAND (rhs, 1))
 621                                  + tree_to_uhwi (access_size);
 622                       if (gpr_size >= VA_LIST_MAX_GPR_SIZE)
 623                         cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 624                       else if (gpr_size > cfun->va_list_gpr_size)
 625                         cfun->va_list_gpr_size = gpr_size;
 626                       continue;
 627                     }
 628
 629                   /* va_arg sequences may contain
 630                      other_ap_temp = ap_temp;
 631                      other_ap_temp = ap_temp + constant;
 632                      other_ap_temp = (some_type *) ap_temp;
 633                      ap = ap_temp;
 634                      statements.  */
 635                   if (rhs == use
 636                       && ((rhs_code == POINTER_PLUS_EXPR
 637                            && (TREE_CODE (gimple_assign_rhs2 (stmt))
 638                                == INTEGER_CST))
 639                           || gimple_assign_cast_p (stmt)
 640                           || (get_gimple_rhs_class (rhs_code)
 641                               == GIMPLE_SINGLE_RHS)))
 642                     {
 643                       tree lhs = gimple_assign_lhs (stmt);
 644
 645                       if (TREE_CODE (lhs) == SSA_NAME
 646                           && bitmap_bit_p (si->va_list_escape_vars,
 647                                            SSA_NAME_VERSION (lhs)))
 648                         continue;
 649
 650                       if (TREE_CODE (lhs) == VAR_DECL
 651                           && bitmap_bit_p (si->va_list_vars,
 652                                            DECL_UID (lhs) + num_ssa_names))
 653                         continue;
 654                     }
 655                   else if (rhs_code == ADDR_EXPR
 656                            && TREE_CODE (TREE_OPERAND (rhs, 0)) == MEM_REF
 657                            && TREE_OPERAND (TREE_OPERAND (rhs, 0), 0) == use)
 658                     {
 659                       tree lhs = gimple_assign_lhs (stmt);
 660
 661                       if (bitmap_bit_p (si->va_list_escape_vars,
 662                                         SSA_NAME_VERSION (lhs)))
 663                         continue;
 664                     }
 665                 }
 666
 667               if (dump_file && (dump_flags & TDF_DETAILS))
 668                 {
 669                   fputs ("va_list escapes in ", dump_file);
 670                   print_gimple_stmt (dump_file, stmt, 0, dump_flags);
 671                   fputc ('\n', dump_file);
 672                 }
 673               return true;
 674             }
 675         }
 676     }
 677
 678   return false;
 679 }
 680
 681
 682 namespace {
 683
 684 const pass_data pass_data_stdarg =
 685 {
 686   GIMPLE_PASS, /* type */
 687   "stdarg", /* name */
 688   OPTGROUP_NONE, /* optinfo_flags */
 689   TV_NONE, /* tv_id */
 690   ( PROP_cfg | PROP_ssa ), /* properties_required */
 691   0, /* properties_provided */
 692   0, /* properties_destroyed */
 693   0, /* todo_flags_start */
 694   0, /* todo_flags_finish */
 695 };
 696
 697 class pass_stdarg : public gimple_opt_pass
 698 {
 699 public:
 700   pass_stdarg (gcc::context *ctxt)
 701     : gimple_opt_pass (pass_data_stdarg, ctxt)
 702   {}
 703
 704   /* opt_pass methods: */
 705   virtual bool gate (function *fun)
 706     {
 707       /* This optimization is only for stdarg functions.  */
 708       return fun->stdarg != 0;
 709     }
 710
 711   virtual unsigned int execute (function *);
 712
 713 }; // class pass_stdarg
 714
 715 unsigned int
 716 pass_stdarg::execute (function *fun)
 717 {
 718   basic_block bb;
 719   bool va_list_escapes = false;
 720   bool va_list_simple_ptr;
 721   struct stdarg_info si;
 722   struct walk_stmt_info wi;
 723   const char *funcname = NULL;
 724   tree cfun_va_list;
 725
 726   fun->va_list_gpr_size = 0;
 727   fun->va_list_fpr_size = 0;
 728   memset (&si, 0, sizeof (si));
 729   si.va_list_vars = BITMAP_ALLOC (NULL);
 730   si.va_list_escape_vars = BITMAP_ALLOC (NULL);
 731
 732   if (dump_file)
 733     funcname = lang_hooks.decl_printable_name (current_function_decl, 2);
 734
 735   cfun_va_list = targetm.fn_abi_va_list (fun->decl);
 736   va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list)
 737                        && (TREE_TYPE (cfun_va_list) == void_type_node
 738                            || TREE_TYPE (cfun_va_list) == char_type_node);
 739   gcc_assert (is_gimple_reg_type (cfun_va_list) == va_list_simple_ptr);
 740
 741   FOR_EACH_BB_FN (bb, fun)
 742     {
 743       gimple_stmt_iterator i;
 744
 745       for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
 746         {
 747           gimple stmt = gsi_stmt (i);
 748           tree callee, ap;
 749
 750           if (!is_gimple_call (stmt))
 751             continue;
 752
 753           callee = gimple_call_fndecl (stmt);
 754           if (!callee
 755               || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
 756             continue;
 757
 758           switch (DECL_FUNCTION_CODE (callee))
 759             {
 760             case BUILT_IN_VA_START:
 761               break;
 762               /* If old style builtins are used, don't optimize anything.  */
 763             case BUILT_IN_SAVEREGS:
 764             case BUILT_IN_NEXT_ARG:
 765               va_list_escapes = true;
 766               continue;
 767             default:
 768               continue;
 769             }
 770
 771           si.va_start_count++;
 772           ap = gimple_call_arg (stmt, 0);
 773
 774           if (TREE_CODE (ap) != ADDR_EXPR)
 775             {
 776               va_list_escapes = true;
 777               break;
 778             }
 779           ap = TREE_OPERAND (ap, 0);
 780           if (TREE_CODE (ap) == ARRAY_REF)
 781             {
 782               if (! integer_zerop (TREE_OPERAND (ap, 1)))
 783                 {
 784                   va_list_escapes = true;
 785                   break;
 786                 }
 787               ap = TREE_OPERAND (ap, 0);
 788             }
 789           if (TYPE_MAIN_VARIANT (TREE_TYPE (ap))
 790               != TYPE_MAIN_VARIANT (targetm.fn_abi_va_list (fun->decl))
 791               || TREE_CODE (ap) != VAR_DECL)
 792             {
 793               va_list_escapes = true;
 794               break;
 795             }
 796
 797           if (is_global_var (ap))
 798             {
 799               va_list_escapes = true;
 800               break;
 801             }
 802
 803           bitmap_set_bit (si.va_list_vars, DECL_UID (ap) + num_ssa_names);
 804
 805           /* VA_START_BB and VA_START_AP will be only used if there is just
 806              one va_start in the function.  */
 807           si.va_start_bb = bb;
 808           si.va_start_ap = ap;
 809         }
 810
 811       if (va_list_escapes)
 812         break;
 813     }
 814
 815   /* If there were no va_start uses in the function, there is no need to
 816      save anything.  */
 817   if (si.va_start_count == 0)
 818     goto finish;
 819
 820   /* If some va_list arguments weren't local, we can't optimize.  */
 821   if (va_list_escapes)
 822     goto finish;
 823
 824   /* For void * or char * va_list, something useful can be done only
 825      if there is just one va_start.  */
 826   if (va_list_simple_ptr && si.va_start_count > 1)
 827     {
 828       va_list_escapes = true;
 829       goto finish;
 830     }
 831
 832   /* For struct * va_list, if the backend didn't tell us what the counter fields
 833      are, there is nothing more we can do.  */
 834   if (!va_list_simple_ptr
 835       && va_list_gpr_counter_field == NULL_TREE
 836       && va_list_fpr_counter_field == NULL_TREE)
 837     {
 838       va_list_escapes = true;
 839       goto finish;
 840     }
 841
 842   /* For void * or char * va_list there is just one counter
 843      (va_list itself).  Use VA_LIST_GPR_SIZE for it.  */
 844   if (va_list_simple_ptr)
 845     fun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
 846
 847   calculate_dominance_info (CDI_DOMINATORS);
 848   memset (&wi, 0, sizeof (wi));
 849   wi.info = si.va_list_vars;
 850
 851   FOR_EACH_BB_FN (bb, fun)
 852     {
 853       si.compute_sizes = -1;
 854       si.bb = bb;
 855
 856       /* For va_list_simple_ptr, we have to check PHI nodes too.  We treat
 857          them as assignments for the purpose of escape analysis.  This is
 858          not needed for non-simple va_list because virtual phis don't perform
 859          any real data movement.  */
 860       if (va_list_simple_ptr)
 861         {
 862           tree lhs, rhs;
 863           use_operand_p uop;
 864           ssa_op_iter soi;
 865
 866           for (gphi_iterator i = gsi_start_phis (bb); !gsi_end_p (i);
 867                gsi_next (&i))
 868             {
 869               gphi *phi = i.phi ();
 870               lhs = PHI_RESULT (phi);
 871
 872               if (virtual_operand_p (lhs))
 873                 continue;
 874
 875               FOR_EACH_PHI_ARG (uop, phi, soi, SSA_OP_USE)
 876                 {
 877                   rhs = USE_FROM_PTR (uop);
 878                   if (va_list_ptr_read (&si, rhs, lhs))
 879                     continue;
 880                   else if (va_list_ptr_write (&si, lhs, rhs))
 881                     continue;
 882                   else
 883                     check_va_list_escapes (&si, lhs, rhs);
 884
 885                   if (si.va_list_escapes)
 886                     {
 887                       if (dump_file && (dump_flags & TDF_DETAILS))
 888                         {
 889                           fputs ("va_list escapes in ", dump_file);
 890                           print_gimple_stmt (dump_file, phi, 0, dump_flags);
 891                           fputc ('\n', dump_file);
 892                         }
 893                       va_list_escapes = true;
 894                     }
 895                 }
 896             }
 897         }
 898
 899       for (gimple_stmt_iterator i = gsi_start_bb (bb);
 900            !gsi_end_p (i) && !va_list_escapes;
 901            gsi_next (&i))
 902         {
 903           gimple stmt = gsi_stmt (i);
 904
 905           /* Don't look at __builtin_va_{start,end}, they are ok.  */
 906           if (is_gimple_call (stmt))
 907             {
 908               tree callee = gimple_call_fndecl (stmt);
 909
 910               if (callee
 911                   && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
 912                   && (DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_START
 913                       || DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_END))
 914                 continue;
 915             }
 916
 917           if (is_gimple_assign (stmt))
 918             {
 919               tree lhs = gimple_assign_lhs (stmt);
 920               tree rhs = gimple_assign_rhs1 (stmt);
 921
 922               if (va_list_simple_ptr)
 923                 {
 924                   if (get_gimple_rhs_class (gimple_assign_rhs_code (stmt))
 925                       == GIMPLE_SINGLE_RHS)
 926                     {
 927                       /* Check for ap ={v} {}.  */
 928                       if (TREE_CLOBBER_P (rhs))
 929                         continue;
 930
 931                       /* Check for tem = ap.  */
 932                       else if (va_list_ptr_read (&si, rhs, lhs))
 933                         continue;
 934
 935                       /* Check for the last insn in:
 936                          tem1 = ap;
 937                          tem2 = tem1 + CST;
 938                          ap = tem2;
 939                          sequence.  */
 940                       else if (va_list_ptr_write (&si, lhs, rhs))
 941                         continue;
 942                     }
 943
 944                   if ((gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
 945                        && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST)
 946                       || CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt))
 947                       || (get_gimple_rhs_class (gimple_assign_rhs_code (stmt))
 948                           == GIMPLE_SINGLE_RHS))
 949                     check_va_list_escapes (&si, lhs, rhs);
 950                 }
 951               else
 952                 {
 953                   if (get_gimple_rhs_class (gimple_assign_rhs_code (stmt))
 954                       == GIMPLE_SINGLE_RHS)
 955                     {
 956                       /* Check for ap ={v} {}.  */
 957                       if (TREE_CLOBBER_P (rhs))
 958                         continue;
 959
 960                       /* Check for ap[0].field = temp.  */
 961                       else if (va_list_counter_struct_op (&si, lhs, rhs, true))
 962                         continue;
 963
 964                       /* Check for temp = ap[0].field.  */
 965                       else if (va_list_counter_struct_op (&si, rhs, lhs,
 966                                                           false))
 967                         continue;
 968                     }
 969
 970                   /* Do any architecture specific checking.  */
 971                   if (targetm.stdarg_optimize_hook
 972                       && targetm.stdarg_optimize_hook (&si, stmt))
 973                     continue;
 974                 }
 975             }
 976           else if (is_gimple_debug (stmt))
 977             continue;
 978
 979           /* All other uses of va_list are either va_copy (that is not handled
 980              in this optimization), taking address of va_list variable or
 981              passing va_list to other functions (in that case va_list might
 982              escape the function and therefore va_start needs to set it up
 983              fully), or some unexpected use of va_list.  None of these should
 984              happen in a gimplified VA_ARG_EXPR.  */
 985           if (si.va_list_escapes
 986               || walk_gimple_op (stmt, find_va_list_reference, &wi))
 987             {
 988               if (dump_file && (dump_flags & TDF_DETAILS))
 989                 {
 990                   fputs ("va_list escapes in ", dump_file);
 991                   print_gimple_stmt (dump_file, stmt, 0, dump_flags);
 992                   fputc ('\n', dump_file);
 993                 }
 994               va_list_escapes = true;
 995             }
 996         }
 997
 998       if (va_list_escapes)
 999         break;
1000     }
1001
1002   if (! va_list_escapes
1003       && va_list_simple_ptr
1004       && ! bitmap_empty_p (si.va_list_escape_vars)
1005       && check_all_va_list_escapes (&si))
1006     va_list_escapes = true;
1007
1008 finish:
1009   if (va_list_escapes)
1010     {
1011       fun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
1012       fun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
1013     }
1014   BITMAP_FREE (si.va_list_vars);
1015   BITMAP_FREE (si.va_list_escape_vars);
1016   free (si.offsets);
1017   if (dump_file)
1018     {
1019       fprintf (dump_file, "%s: va_list escapes %d, needs to save ",
1020                funcname, (int) va_list_escapes);
1021       if (fun->va_list_gpr_size >= VA_LIST_MAX_GPR_SIZE)
1022         fputs ("all", dump_file);
1023       else
1024         fprintf (dump_file, "%d", cfun->va_list_gpr_size);
1025       fputs (" GPR units and ", dump_file);
1026       if (fun->va_list_fpr_size >= VA_LIST_MAX_FPR_SIZE)
1027         fputs ("all", dump_file);
1028       else
1029         fprintf (dump_file, "%d", cfun->va_list_fpr_size);
1030       fputs (" FPR units.\n", dump_file);
1031     }
1032   return 0;
1033 }
1034
1035 } // anon namespace
1036
1037 gimple_opt_pass *
1038 make_pass_stdarg (gcc::context *ctxt)
1039 {
1040   return new pass_stdarg (ctxt);
1041 }