gcc/tree-stdarg.c

   1 /* Pass computing data for optimizing stdarg functions.
   2    Copyright (C) 2004, 2005 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 2, 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 COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  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 "diagnostic.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   edge *stack, e;
  51   edge_iterator ei;
  52   int sp;
  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   stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge));
  63   sp = 0;
  64
  65   visited = sbitmap_alloc (last_basic_block);
  66   sbitmap_zero (visited);
  67   ret = true;
  68
  69   FOR_EACH_EDGE (e, ei, va_arg_bb->preds)
  70     stack[sp++] = e;
  71
  72   while (sp)
  73     {
  74       basic_block src;
  75
  76       --sp;
  77       e = stack[sp];
  78       src = e->src;
  79
  80       if (e->flags & EDGE_COMPLEX)
  81         {
  82           ret = false;
  83           break;
  84         }
  85
  86       if (src == va_start_bb)
  87         continue;
  88
  89       /* va_arg_bb can be executed more times than va_start_bb.  */
  90       if (src == va_arg_bb)
  91         {
  92           ret = false;
  93           break;
  94         }
  95
  96       gcc_assert (src != ENTRY_BLOCK_PTR);
  97
  98       if (! TEST_BIT (visited, src->index))
  99         {
 100           SET_BIT (visited, src->index);
 101           FOR_EACH_EDGE (e, ei, src->preds)
 102             stack[sp++] = e;
 103         }
 104     }
 105
 106   free (stack);
 107   sbitmap_free (visited);
 108   return ret;
 109 }
 110
 111
 112 /* For statement COUNTER = RHS, if RHS is COUNTER + constant,
 113    return constant, otherwise return (unsigned HOST_WIDE_INT) -1.
 114    GPR_P is true if this is GPR counter.  */
 115
 116 static unsigned HOST_WIDE_INT
 117 va_list_counter_bump (struct stdarg_info *si, tree counter, tree rhs,
 118                       bool gpr_p)
 119 {
 120   tree stmt, lhs, orig_lhs;
 121   unsigned HOST_WIDE_INT ret = 0, val, counter_val;
 122   unsigned int max_size;
 123
 124   if (si->offsets == NULL)
 125     {
 126       unsigned int i;
 127
 128       si->offsets = xmalloc (num_ssa_names * sizeof (int));
 129       for (i = 0; i < num_ssa_names; ++i)
 130         si->offsets[i] = -1;
 131     }
 132
 133   counter_val = gpr_p ? cfun->va_list_gpr_size : cfun->va_list_fpr_size;
 134   max_size = gpr_p ? VA_LIST_MAX_GPR_SIZE : VA_LIST_MAX_FPR_SIZE;
 135   orig_lhs = lhs = rhs;
 136   while (lhs)
 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 (TREE_CODE (stmt) != MODIFY_EXPR
 153           || TREE_OPERAND (stmt, 0) != lhs)
 154         return (unsigned HOST_WIDE_INT) -1;
 155
 156       rhs = TREE_OPERAND (stmt, 1);
 157       if (TREE_CODE (rhs) == WITH_SIZE_EXPR)
 158         rhs = TREE_OPERAND (rhs, 0);
 159
 160       if (TREE_CODE (rhs) == SSA_NAME)
 161         {
 162           lhs = rhs;
 163           continue;
 164         }
 165
 166       if ((TREE_CODE (rhs) == NOP_EXPR
 167            || TREE_CODE (rhs) == CONVERT_EXPR)
 168           && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
 169         {
 170           lhs = TREE_OPERAND (rhs, 0);
 171           continue;
 172         }
 173
 174       if (TREE_CODE (rhs) == PLUS_EXPR
 175           && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
 176           && TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST
 177           && host_integerp (TREE_OPERAND (rhs, 1), 1))
 178         {
 179           ret += tree_low_cst (TREE_OPERAND (rhs, 1), 1);
 180           lhs = TREE_OPERAND (rhs, 0);
 181           continue;
 182         }
 183
 184       if (TREE_CODE (counter) != TREE_CODE (rhs))
 185         return (unsigned HOST_WIDE_INT) -1;
 186
 187       if (TREE_CODE (counter) == COMPONENT_REF)
 188         {
 189           if (get_base_address (counter) != get_base_address (rhs)
 190               || TREE_CODE (TREE_OPERAND (rhs, 1)) != FIELD_DECL
 191               || TREE_OPERAND (counter, 1) != TREE_OPERAND (rhs, 1))
 192             return (unsigned HOST_WIDE_INT) -1;
 193         }
 194       else if (counter != rhs)
 195         return (unsigned HOST_WIDE_INT) -1;
 196
 197       lhs = NULL;
 198     }
 199
 200   lhs = orig_lhs;
 201   val = ret + counter_val;
 202   while (lhs)
 203     {
 204       if (si->offsets[SSA_NAME_VERSION (lhs)] != -1)
 205         break;
 206
 207       if (val >= max_size)
 208         si->offsets[SSA_NAME_VERSION (lhs)] = max_size;
 209       else
 210         si->offsets[SSA_NAME_VERSION (lhs)] = val;
 211
 212       stmt = SSA_NAME_DEF_STMT (lhs);
 213
 214       rhs = TREE_OPERAND (stmt, 1);
 215       if (TREE_CODE (rhs) == WITH_SIZE_EXPR)
 216         rhs = TREE_OPERAND (rhs, 0);
 217
 218       if (TREE_CODE (rhs) == SSA_NAME)
 219         {
 220           lhs = rhs;
 221           continue;
 222         }
 223
 224       if ((TREE_CODE (rhs) == NOP_EXPR
 225            || TREE_CODE (rhs) == CONVERT_EXPR)
 226           && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
 227         {
 228           lhs = TREE_OPERAND (rhs, 0);
 229           continue;
 230         }
 231
 232       if (TREE_CODE (rhs) == PLUS_EXPR
 233           && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
 234           && TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST
 235           && host_integerp (TREE_OPERAND (rhs, 1), 1))
 236         {
 237           val -= tree_low_cst (TREE_OPERAND (rhs, 1), 1);
 238           lhs = TREE_OPERAND (rhs, 0);
 239           continue;
 240         }
 241
 242       lhs = NULL;
 243     }
 244
 245   return ret;
 246 }
 247
 248
 249 /* Called by walk_tree to look for references to va_list variables.  */
 250
 251 static tree
 252 find_va_list_reference (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
 253                         void *data)
 254 {
 255   bitmap va_list_vars = (bitmap) data;
 256   tree var = *tp;
 257
 258   if (TREE_CODE (var) == SSA_NAME)
 259     var = SSA_NAME_VAR (var);
 260
 261   if (TREE_CODE (var) == VAR_DECL
 262       && bitmap_bit_p (va_list_vars, var_ann (var)->uid))
 263     return var;
 264
 265   return NULL_TREE;
 266 }
 267
 268
 269 /* Helper function of va_list_counter_struct_op.  Compute
 270    cfun->va_list_{g,f}pr_size.  AP is a va_list GPR/FPR counter,
 271    if WRITE_P is true, seen in AP = VAR, otherwise seen in VAR = AP
 272    statement.  GPR_P is true if AP is a GPR counter, false if it is
 273    a FPR counter.  */
 274
 275 static void
 276 va_list_counter_op (struct stdarg_info *si, tree ap, tree var, bool gpr_p,
 277                     bool write_p)
 278 {
 279   unsigned HOST_WIDE_INT increment;
 280
 281   if (si->compute_sizes < 0)
 282     {
 283       si->compute_sizes = 0;
 284       if (si->va_start_count == 1
 285           && reachable_at_most_once (si->bb, si->va_start_bb))
 286         si->compute_sizes = 1;
 287
 288       if (dump_file && (dump_flags & TDF_DETAILS))
 289         fprintf (dump_file,
 290                  "bb%d will %sbe executed at most once for each va_start "
 291                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 292                  si->va_start_bb->index);
 293     }
 294
 295   if (write_p
 296       && si->compute_sizes
 297       && (increment = va_list_counter_bump (si, ap, var, gpr_p)) + 1 > 1)
 298     {
 299       if (gpr_p && cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE)
 300         {
 301           cfun->va_list_gpr_size += increment;
 302           return;
 303         }
 304
 305       if (!gpr_p && cfun->va_list_fpr_size + increment < VA_LIST_MAX_FPR_SIZE)
 306         {
 307           cfun->va_list_fpr_size += increment;
 308           return;
 309         }
 310     }
 311
 312   if (write_p || !si->compute_sizes)
 313     {
 314       if (gpr_p)
 315         cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 316       else
 317         cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
 318     }
 319 }
 320
 321
 322 /* If AP is a va_list GPR/FPR counter, compute cfun->va_list_{g,f}pr_size.
 323    If WRITE_P is true, AP has been seen in AP = VAR assignment, if WRITE_P
 324    is false, AP has been seen in VAR = AP assignment.
 325    Return true if the AP = VAR (resp. VAR = AP) statement is a recognized
 326    va_arg operation that doesn't cause the va_list variable to escape
 327    current function.  */
 328
 329 static bool
 330 va_list_counter_struct_op (struct stdarg_info *si, tree ap, tree var,
 331                            bool write_p)
 332 {
 333   tree base;
 334
 335   if (TREE_CODE (ap) != COMPONENT_REF
 336       || TREE_CODE (TREE_OPERAND (ap, 1)) != FIELD_DECL)
 337     return false;
 338
 339   if (TREE_CODE (var) != SSA_NAME
 340       || bitmap_bit_p (si->va_list_vars, var_ann (SSA_NAME_VAR (var))->uid))
 341     return false;
 342
 343   base = get_base_address (ap);
 344   if (TREE_CODE (base) != VAR_DECL
 345       || !bitmap_bit_p (si->va_list_vars, var_ann (base)->uid))
 346     return false;
 347
 348   if (TREE_OPERAND (ap, 1) == va_list_gpr_counter_field)
 349     va_list_counter_op (si, ap, var, true, write_p);
 350   else if (TREE_OPERAND (ap, 1) == va_list_fpr_counter_field)
 351     va_list_counter_op (si, ap, var, false, write_p);
 352
 353   return true;
 354 }
 355
 356
 357 /* Check for TEM = AP.  Return true if found and the caller shouldn't
 358    search for va_list references in the statement.  */
 359
 360 static bool
 361 va_list_ptr_read (struct stdarg_info *si, tree ap, tree tem)
 362 {
 363   if (TREE_CODE (ap) != VAR_DECL
 364       || !bitmap_bit_p (si->va_list_vars, var_ann (ap)->uid))
 365     return false;
 366
 367   if (TREE_CODE (tem) != SSA_NAME
 368       || bitmap_bit_p (si->va_list_vars,
 369                        var_ann (SSA_NAME_VAR (tem))->uid)
 370       || is_global_var (SSA_NAME_VAR (tem)))
 371     return false;
 372
 373   if (si->compute_sizes < 0)
 374     {
 375       si->compute_sizes = 0;
 376       if (si->va_start_count == 1
 377           && reachable_at_most_once (si->bb, si->va_start_bb))
 378         si->compute_sizes = 1;
 379
 380       if (dump_file && (dump_flags & TDF_DETAILS))
 381         fprintf (dump_file,
 382                  "bb%d will %sbe executed at most once for each va_start "
 383                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 384                  si->va_start_bb->index);
 385     }
 386
 387   /* For void * or char * va_list types, there is just one counter.
 388      If va_arg is used in a loop, we don't know how many registers need
 389      saving.  */
 390   if (! si->compute_sizes)
 391     return false;
 392
 393   if (va_list_counter_bump (si, ap, tem, true) == (unsigned HOST_WIDE_INT) -1)
 394     return false;
 395
 396   /* Note the temporary, as we need to track whether it doesn't escape
 397      the current function.  */
 398   bitmap_set_bit (si->va_list_escape_vars,
 399                   var_ann (SSA_NAME_VAR (tem))->uid);
 400   return true;
 401 }
 402
 403
 404 /* Check for:
 405      tem1 = AP;
 406      TEM2 = tem1 + CST;
 407      AP = TEM2;
 408    sequence and update cfun->va_list_gpr_size.  Return true if found.  */
 409
 410 static bool
 411 va_list_ptr_write (struct stdarg_info *si, tree ap, tree tem2)
 412 {
 413   unsigned HOST_WIDE_INT increment;
 414
 415   if (TREE_CODE (ap) != VAR_DECL
 416       || !bitmap_bit_p (si->va_list_vars, var_ann (ap)->uid))
 417     return false;
 418
 419   if (TREE_CODE (tem2) != SSA_NAME
 420       || bitmap_bit_p (si->va_list_vars, var_ann (SSA_NAME_VAR (tem2))->uid))
 421     return false;
 422
 423   if (si->compute_sizes <= 0)
 424     return false;
 425
 426   increment = va_list_counter_bump (si, ap, tem2, true);
 427   if (increment + 1 <= 1)
 428     return false;
 429
 430   if (cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE)
 431     cfun->va_list_gpr_size += increment;
 432   else
 433     cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 434
 435   return true;
 436 }
 437
 438
 439 /* If RHS is X, (some type *) X or X + CST for X a temporary variable
 440    containing value of some va_list variable plus optionally some constant,
 441    either set si->va_list_escapes or add LHS to si->va_list_escape_vars,
 442    depending whether LHS is a function local temporary.  */
 443
 444 static void
 445 check_va_list_escapes (struct stdarg_info *si, tree lhs, tree rhs)
 446 {
 447   if (! POINTER_TYPE_P (TREE_TYPE (rhs)))
 448     return;
 449
 450   if ((TREE_CODE (rhs) == PLUS_EXPR
 451        && TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST)
 452       || TREE_CODE (rhs) == NOP_EXPR
 453       || TREE_CODE (rhs) == CONVERT_EXPR)
 454     rhs = TREE_OPERAND (rhs, 0);
 455
 456   if (TREE_CODE (rhs) != SSA_NAME
 457       || ! bitmap_bit_p (si->va_list_escape_vars,
 458                          var_ann (SSA_NAME_VAR (rhs))->uid))
 459     return;
 460
 461   if (TREE_CODE (lhs) != SSA_NAME || is_global_var (SSA_NAME_VAR (lhs)))
 462     {
 463       si->va_list_escapes = true;
 464       return;
 465     }
 466
 467   if (si->compute_sizes < 0)
 468     {
 469       si->compute_sizes = 0;
 470       if (si->va_start_count == 1
 471           && reachable_at_most_once (si->bb, si->va_start_bb))
 472         si->compute_sizes = 1;
 473
 474       if (dump_file && (dump_flags & TDF_DETAILS))
 475         fprintf (dump_file,
 476                  "bb%d will %sbe executed at most once for each va_start "
 477                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 478                  si->va_start_bb->index);
 479     }
 480
 481   /* For void * or char * va_list types, there is just one counter.
 482      If va_arg is used in a loop, we don't know how many registers need
 483      saving.  */
 484   if (! si->compute_sizes)
 485     {
 486       si->va_list_escapes = true;
 487       return;
 488     }
 489
 490   if (va_list_counter_bump (si, si->va_start_ap, lhs, true)
 491       == (unsigned HOST_WIDE_INT) -1)
 492     {
 493       si->va_list_escapes = true;
 494       return;
 495     }
 496
 497   bitmap_set_bit (si->va_list_escape_vars,
 498                   var_ann (SSA_NAME_VAR (lhs))->uid);
 499 }
 500
 501
 502 /* Check all uses of temporaries from si->va_list_escape_vars bitmap.
 503    Return true if va_list might be escaping.  */
 504
 505 static bool
 506 check_all_va_list_escapes (struct stdarg_info *si)
 507 {
 508   basic_block bb;
 509
 510   FOR_EACH_BB (bb)
 511     {
 512       block_stmt_iterator i;
 513
 514       for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
 515         {
 516           tree stmt = bsi_stmt (i), use;
 517           ssa_op_iter iter;
 518
 519           FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES)
 520             {
 521               if (! bitmap_bit_p (si->va_list_escape_vars,
 522                                   var_ann (SSA_NAME_VAR (use))->uid))
 523                 continue;
 524
 525               if (TREE_CODE (stmt) == MODIFY_EXPR)
 526                 {
 527                   tree lhs = TREE_OPERAND (stmt, 0);
 528                   tree rhs = TREE_OPERAND (stmt, 1);
 529
 530                   if (TREE_CODE (rhs) == WITH_SIZE_EXPR)
 531                     rhs = TREE_OPERAND (rhs, 0);
 532
 533                   /* x = *ap_temp;  */
 534                   if (TREE_CODE (rhs) == INDIRECT_REF
 535                       && TREE_OPERAND (rhs, 0) == use
 536                       && TYPE_SIZE_UNIT (TREE_TYPE (rhs))
 537                       && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (rhs)), 1)
 538                       && si->offsets[SSA_NAME_VERSION (use)] != -1)
 539                     {
 540                       unsigned HOST_WIDE_INT gpr_size;
 541                       tree access_size = TYPE_SIZE_UNIT (TREE_TYPE (rhs));
 542
 543                       gpr_size = si->offsets[SSA_NAME_VERSION (use)]
 544                                  + tree_low_cst (access_size, 1);
 545                       if (gpr_size >= VA_LIST_MAX_GPR_SIZE)
 546                         cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 547                       else if (gpr_size > cfun->va_list_gpr_size)
 548                         cfun->va_list_gpr_size = gpr_size;
 549                       continue;
 550                     }
 551
 552                   /* va_arg sequences may contain
 553                      other_ap_temp = ap_temp;
 554                      other_ap_temp = ap_temp + constant;
 555                      other_ap_temp = (some_type *) ap_temp;
 556                      ap = ap_temp;
 557                      statements.  */
 558                   if ((TREE_CODE (rhs) == PLUS_EXPR
 559                        && TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST)
 560                       || TREE_CODE (rhs) == NOP_EXPR
 561                       || TREE_CODE (rhs) == CONVERT_EXPR)
 562                     rhs = TREE_OPERAND (rhs, 0);
 563
 564                   if (rhs == use)
 565                     {
 566                       if (TREE_CODE (lhs) == SSA_NAME
 567                           && bitmap_bit_p (si->va_list_escape_vars,
 568                                            var_ann (SSA_NAME_VAR (lhs))->uid))
 569                         continue;
 570
 571                       if (TREE_CODE (lhs) == VAR_DECL
 572                           && bitmap_bit_p (si->va_list_vars,
 573                                            var_ann (lhs)->uid))
 574                         continue;
 575                     }
 576                 }
 577
 578               if (dump_file && (dump_flags & TDF_DETAILS))
 579                 {
 580                   fputs ("va_list escapes in ", dump_file);
 581                   print_generic_expr (dump_file, stmt, dump_flags);
 582                   fputc ('\n', dump_file);
 583                 }
 584               return true;
 585             }
 586         }
 587     }
 588
 589   return false;
 590 }
 591
 592
 593 /* Return true if this optimization pass should be done.
 594    It makes only sense for stdarg functions.  */
 595
 596 static bool
 597 gate_optimize_stdarg (void)
 598 {
 599   /* This optimization is only for stdarg functions.  */
 600   return current_function_stdarg != 0;
 601 }
 602
 603
 604 /* Entry point to the stdarg optimization pass.  */
 605
 606 static void
 607 execute_optimize_stdarg (void)
 608 {
 609   basic_block bb;
 610   bool va_list_escapes = false;
 611   bool va_list_simple_ptr;
 612   struct stdarg_info si;
 613   const char *funcname = NULL;
 614
 615   cfun->va_list_gpr_size = 0;
 616   cfun->va_list_fpr_size = 0;
 617   memset (&si, 0, sizeof (si));
 618   si.va_list_vars = BITMAP_ALLOC (NULL);
 619   si.va_list_escape_vars = BITMAP_ALLOC (NULL);
 620
 621   if (dump_file)
 622     funcname = lang_hooks.decl_printable_name (current_function_decl, 2);
 623
 624   va_list_simple_ptr = POINTER_TYPE_P (va_list_type_node)
 625                        && (TREE_TYPE (va_list_type_node) == void_type_node
 626                            || TREE_TYPE (va_list_type_node) == char_type_node);
 627
 628   FOR_EACH_BB (bb)
 629     {
 630       block_stmt_iterator i;
 631
 632       for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
 633         {
 634           tree stmt = bsi_stmt (i);
 635           tree call = get_call_expr_in (stmt), callee;
 636           tree ap;
 637
 638           if (!call)
 639             continue;
 640
 641           callee = get_callee_fndecl (call);
 642           if (!callee
 643               || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
 644             continue;
 645
 646           switch (DECL_FUNCTION_CODE (callee))
 647             {
 648             case BUILT_IN_VA_START:
 649               break;
 650               /* If old style builtins are used, don't optimize anything.  */
 651             case BUILT_IN_SAVEREGS:
 652             case BUILT_IN_STDARG_START:
 653             case BUILT_IN_ARGS_INFO:
 654             case BUILT_IN_NEXT_ARG:
 655               va_list_escapes = true;
 656               continue;
 657             default:
 658               continue;
 659             }
 660
 661           si.va_start_count++;
 662           ap = TREE_VALUE (TREE_OPERAND (call, 1));
 663
 664           if (TREE_CODE (ap) != ADDR_EXPR)
 665             {
 666               va_list_escapes = true;
 667               break;
 668             }
 669           ap = TREE_OPERAND (ap, 0);
 670           if (TREE_CODE (ap) == ARRAY_REF)
 671             {
 672               if (! integer_zerop (TREE_OPERAND (ap, 1)))
 673                 {
 674                   va_list_escapes = true;
 675                   break;
 676                 }
 677               ap = TREE_OPERAND (ap, 0);
 678             }
 679           if (TYPE_MAIN_VARIANT (TREE_TYPE (ap))
 680               != TYPE_MAIN_VARIANT (va_list_type_node)
 681               || TREE_CODE (ap) != VAR_DECL)
 682             {
 683               va_list_escapes = true;
 684               break;
 685             }
 686
 687           if (is_global_var (ap))
 688             {
 689               va_list_escapes = true;
 690               break;
 691             }
 692
 693           bitmap_set_bit (si.va_list_vars, var_ann (ap)->uid);
 694
 695           /* VA_START_BB and VA_START_AP will be only used if there is just
 696              one va_start in the function.  */
 697           si.va_start_bb = bb;
 698           si.va_start_ap = ap;
 699         }
 700
 701       if (va_list_escapes)
 702         break;
 703     }
 704
 705   /* If there were no va_start uses in the function, there is no need to
 706      save anything.  */
 707   if (si.va_start_count == 0)
 708     goto finish;
 709
 710   /* If some va_list arguments weren't local, we can't optimize.  */
 711   if (va_list_escapes)
 712     goto finish;
 713
 714   /* For void * or char * va_list, something useful can be done only
 715      if there is just one va_start.  */
 716   if (va_list_simple_ptr && si.va_start_count > 1)
 717     {
 718       va_list_escapes = true;
 719       goto finish;
 720     }
 721
 722   /* For struct * va_list, if the backend didn't tell us what the counter fields
 723      are, there is nothing more we can do.  */
 724   if (!va_list_simple_ptr
 725       && va_list_gpr_counter_field == NULL_TREE
 726       && va_list_fpr_counter_field == NULL_TREE)
 727     {
 728       va_list_escapes = true;
 729       goto finish;
 730     }
 731
 732   /* For void * or char * va_list there is just one counter
 733      (va_list itself).  Use VA_LIST_GPR_SIZE for it.  */
 734   if (va_list_simple_ptr)
 735     cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
 736
 737   FOR_EACH_BB (bb)
 738     {
 739       block_stmt_iterator i;
 740
 741       si.compute_sizes = -1;
 742       si.bb = bb;
 743       for (i = bsi_start (bb);
 744            !bsi_end_p (i) && !va_list_escapes;
 745            bsi_next (&i))
 746         {
 747           tree stmt = bsi_stmt (i);
 748           tree call;
 749
 750           /* Don't look at __builtin_va_{start,end}, they are ok.  */
 751           call = get_call_expr_in (stmt);
 752           if (call)
 753             {
 754               tree callee = get_callee_fndecl (call);
 755
 756               if (callee
 757                   && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
 758                   && (DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_START
 759                       || DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_END))
 760                 continue;
 761             }
 762
 763           if (TREE_CODE (stmt) == MODIFY_EXPR)
 764             {
 765               tree lhs = TREE_OPERAND (stmt, 0);
 766               tree rhs = TREE_OPERAND (stmt, 1);
 767
 768               if (TREE_CODE (rhs) == WITH_SIZE_EXPR)
 769                 rhs = TREE_OPERAND (rhs, 0);
 770
 771               if (va_list_simple_ptr)
 772                 {
 773                   /* Check for tem = ap.  */
 774                   if (va_list_ptr_read (&si, rhs, lhs))
 775                     continue;
 776
 777                   /* Check for the last insn in:
 778                      tem1 = ap;
 779                      tem2 = tem1 + CST;
 780                      ap = tem2;
 781                      sequence.  */
 782                   else if (va_list_ptr_write (&si, lhs, rhs))
 783                     continue;
 784
 785                   else
 786                     check_va_list_escapes (&si, lhs, rhs);
 787                 }
 788               else
 789                 {
 790                   /* Check for ap[0].field = temp.  */
 791                   if (va_list_counter_struct_op (&si, lhs, rhs, true))
 792                     continue;
 793
 794                   /* Check for temp = ap[0].field.  */
 795                   else if (va_list_counter_struct_op (&si, rhs, lhs, false))
 796                     continue;
 797
 798                   /* Do any architecture specific checking.  */
 799                   else if (targetm.stdarg_optimize_hook
 800                            && targetm.stdarg_optimize_hook (&si, lhs, rhs))
 801                     continue;
 802                 }
 803             }
 804
 805           /* All other uses of va_list are either va_copy (that is not handled
 806              in this optimization), taking address of va_list variable or
 807              passing va_list to other functions (in that case va_list might
 808              escape the function and therefore va_start needs to set it up
 809              fully), or some unexpected use of va_list.  None of these should
 810              happen in a gimplified VA_ARG_EXPR.  */
 811           if (si.va_list_escapes
 812               || walk_tree (&stmt, find_va_list_reference,
 813                             si.va_list_vars, NULL))
 814             {
 815               if (dump_file && (dump_flags & TDF_DETAILS))
 816                 {
 817                   fputs ("va_list escapes in ", dump_file);
 818                   print_generic_expr (dump_file, stmt, dump_flags);
 819                   fputc ('\n', dump_file);
 820                 }
 821               va_list_escapes = true;
 822             }
 823         }
 824
 825       if (va_list_escapes)
 826         break;
 827     }
 828
 829   if (! va_list_escapes
 830       && va_list_simple_ptr
 831       && ! bitmap_empty_p (si.va_list_escape_vars)
 832       && check_all_va_list_escapes (&si))
 833     va_list_escapes = true;
 834
 835 finish:
 836   if (va_list_escapes)
 837     {
 838       cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 839       cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
 840     }
 841   BITMAP_FREE (si.va_list_vars);
 842   BITMAP_FREE (si.va_list_escape_vars);
 843   free (si.offsets);
 844   if (dump_file)
 845     {
 846       fprintf (dump_file, "%s: va_list escapes %d, needs to save ",
 847                funcname, (int) va_list_escapes);
 848       if (cfun->va_list_gpr_size >= VA_LIST_MAX_GPR_SIZE)
 849         fputs ("all", dump_file);
 850       else
 851         fprintf (dump_file, "%d", cfun->va_list_gpr_size);
 852       fputs (" GPR units and ", dump_file);
 853       if (cfun->va_list_fpr_size >= VA_LIST_MAX_FPR_SIZE)
 854         fputs ("all", dump_file);
 855       else
 856         fprintf (dump_file, "%d", cfun->va_list_fpr_size);
 857       fputs (" FPR units.\n", dump_file);
 858     }
 859 }
 860
 861
 862 struct tree_opt_pass pass_stdarg =
 863 {
 864   "stdarg",                             /* name */
 865   gate_optimize_stdarg,                 /* gate */
 866   execute_optimize_stdarg,              /* execute */
 867   NULL,                                 /* sub */
 868   NULL,                                 /* next */
 869   0,                                    /* static_pass_number */
 870   0,                                    /* tv_id */
 871   PROP_cfg | PROP_ssa | PROP_alias,     /* properties_required */
 872   0,                                    /* properties_provided */
 873   0,                                    /* properties_destroyed */
 874   0,                                    /* todo_flags_start */
 875   TODO_dump_func,                       /* todo_flags_finish */
 876   0                                     /* letter */
 877 };