gcc/tree-stdarg.c

   1 /* Pass computing data for optimizing stdarg functions.
   2    Copyright (C) 2004-2013 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 "tree.h"
  26 #include "function.h"
  27 #include "langhooks.h"
  28 #include "gimple-pretty-print.h"
  29 #include "target.h"
  30 #include "tree-ssa.h"
  31 #include "tree-pass.h"
  32 #include "tree-stdarg.h"
  33
  34 /* A simple pass that attempts to optimize stdarg functions on architectures
  35    that need to save register arguments to stack on entry to stdarg functions.
  36    If the function doesn't use any va_start macros, no registers need to
  37    be saved.  If va_start macros are used, the va_list variables don't escape
  38    the function, it is only necessary to save registers that will be used
  39    in va_arg macros.  E.g. if va_arg is only used with integral types
  40    in the function, floating point registers don't need to be saved, etc.  */
  41
  42
  43 /* Return true if basic block VA_ARG_BB is dominated by VA_START_BB and
  44    is executed at most as many times as VA_START_BB.  */
  45
  46 static bool
  47 reachable_at_most_once (basic_block va_arg_bb, basic_block va_start_bb)
  48 {
  49   vec<edge> stack = vNULL;
  50   edge e;
  51   edge_iterator ei;
  52   sbitmap visited;
  53   bool ret;
  54
  55   if (va_arg_bb == va_start_bb)
  56     return true;
  57
  58   if (! dominated_by_p (CDI_DOMINATORS, va_arg_bb, va_start_bb))
  59     return false;
  60
  61   visited = sbitmap_alloc (last_basic_block);
  62   bitmap_clear (visited);
  63   ret = true;
  64
  65   FOR_EACH_EDGE (e, ei, va_arg_bb->preds)
  66     stack.safe_push (e);
  67
  68   while (! stack.is_empty ())
  69     {
  70       basic_block src;
  71
  72       e = stack.pop ();
  73       src = e->src;
  74
  75       if (e->flags & EDGE_COMPLEX)
  76         {
  77           ret = false;
  78           break;
  79         }
  80
  81       if (src == va_start_bb)
  82         continue;
  83
  84       /* va_arg_bb can be executed more times than va_start_bb.  */
  85       if (src == va_arg_bb)
  86         {
  87           ret = false;
  88           break;
  89         }
  90
  91       gcc_assert (src != ENTRY_BLOCK_PTR);
  92
  93       if (! bitmap_bit_p (visited, src->index))
  94         {
  95           bitmap_set_bit (visited, src->index);
  96           FOR_EACH_EDGE (e, ei, src->preds)
  97             stack.safe_push (e);
  98         }
  99     }
 100
 101   stack.release ();
 102   sbitmap_free (visited);
 103   return ret;
 104 }
 105
 106
 107 /* For statement COUNTER = RHS, if RHS is COUNTER + constant,
 108    return constant, otherwise return HOST_WIDE_INT_M1U.
 109    GPR_P is true if this is GPR counter.  */
 110
 111 static unsigned HOST_WIDE_INT
 112 va_list_counter_bump (struct stdarg_info *si, tree counter, tree rhs,
 113                       bool gpr_p)
 114 {
 115   tree lhs, orig_lhs;
 116   gimple stmt;
 117   unsigned HOST_WIDE_INT ret = 0, val, counter_val;
 118   unsigned int max_size;
 119
 120   if (si->offsets == NULL)
 121     {
 122       unsigned int i;
 123
 124       si->offsets = XNEWVEC (int, num_ssa_names);
 125       for (i = 0; i < num_ssa_names; ++i)
 126         si->offsets[i] = -1;
 127     }
 128
 129   counter_val = gpr_p ? cfun->va_list_gpr_size : cfun->va_list_fpr_size;
 130   max_size = gpr_p ? VA_LIST_MAX_GPR_SIZE : VA_LIST_MAX_FPR_SIZE;
 131   orig_lhs = lhs = rhs;
 132   while (lhs)
 133     {
 134       enum tree_code rhs_code;
 135       tree rhs1;
 136
 137       if (si->offsets[SSA_NAME_VERSION (lhs)] != -1)
 138         {
 139           if (counter_val >= max_size)
 140             {
 141               ret = max_size;
 142               break;
 143             }
 144
 145           ret -= counter_val - si->offsets[SSA_NAME_VERSION (lhs)];
 146           break;
 147         }
 148
 149       stmt = SSA_NAME_DEF_STMT (lhs);
 150
 151       if (!is_gimple_assign (stmt) || gimple_assign_lhs (stmt) != lhs)
 152         return HOST_WIDE_INT_M1U;
 153
 154       rhs_code = gimple_assign_rhs_code (stmt);
 155       rhs1 = gimple_assign_rhs1 (stmt);
 156       if ((get_gimple_rhs_class (rhs_code) == GIMPLE_SINGLE_RHS
 157            || gimple_assign_cast_p (stmt))
 158           && TREE_CODE (rhs1) == SSA_NAME)
 159         {
 160           lhs = rhs1;
 161           continue;
 162         }
 163
 164       if ((rhs_code == POINTER_PLUS_EXPR
 165            || rhs_code == PLUS_EXPR)
 166           && TREE_CODE (rhs1) == SSA_NAME
 167           && host_integerp (gimple_assign_rhs2 (stmt), 1))
 168         {
 169           ret += tree_low_cst (gimple_assign_rhs2 (stmt), 1);
 170           lhs = rhs1;
 171           continue;
 172         }
 173
 174       if (rhs_code == ADDR_EXPR
 175           && TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF
 176           && TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0)) == SSA_NAME
 177           && host_integerp (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1), 1))
 178         {
 179           ret += tree_low_cst (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1), 1);
 180           lhs = TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0);
 181           continue;
 182         }
 183
 184       if (get_gimple_rhs_class (rhs_code) != GIMPLE_SINGLE_RHS)
 185         return HOST_WIDE_INT_M1U;
 186
 187       rhs = gimple_assign_rhs1 (stmt);
 188       if (TREE_CODE (counter) != TREE_CODE (rhs))
 189         return HOST_WIDE_INT_M1U;
 190
 191       if (TREE_CODE (counter) == COMPONENT_REF)
 192         {
 193           if (get_base_address (counter) != get_base_address (rhs)
 194               || TREE_CODE (TREE_OPERAND (rhs, 1)) != FIELD_DECL
 195               || TREE_OPERAND (counter, 1) != TREE_OPERAND (rhs, 1))
 196             return HOST_WIDE_INT_M1U;
 197         }
 198       else if (counter != rhs)
 199         return HOST_WIDE_INT_M1U;
 200
 201       lhs = NULL;
 202     }
 203
 204   lhs = orig_lhs;
 205   val = ret + counter_val;
 206   while (lhs)
 207     {
 208       enum tree_code rhs_code;
 209       tree rhs1;
 210
 211       if (si->offsets[SSA_NAME_VERSION (lhs)] != -1)
 212         break;
 213
 214       if (val >= max_size)
 215         si->offsets[SSA_NAME_VERSION (lhs)] = max_size;
 216       else
 217         si->offsets[SSA_NAME_VERSION (lhs)] = val;
 218
 219       stmt = SSA_NAME_DEF_STMT (lhs);
 220
 221       rhs_code = gimple_assign_rhs_code (stmt);
 222       rhs1 = gimple_assign_rhs1 (stmt);
 223       if ((get_gimple_rhs_class (rhs_code) == GIMPLE_SINGLE_RHS
 224            || gimple_assign_cast_p (stmt))
 225           && TREE_CODE (rhs1) == SSA_NAME)
 226         {
 227           lhs = rhs1;
 228           continue;
 229         }
 230
 231       if ((rhs_code == POINTER_PLUS_EXPR
 232            || rhs_code == PLUS_EXPR)
 233           && TREE_CODE (rhs1) == SSA_NAME
 234           && host_integerp (gimple_assign_rhs2 (stmt), 1))
 235         {
 236           val -= tree_low_cst (gimple_assign_rhs2 (stmt), 1);
 237           lhs = rhs1;
 238           continue;
 239         }
 240
 241       if (rhs_code == ADDR_EXPR
 242           && TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF
 243           && TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0)) == SSA_NAME
 244           && host_integerp (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1), 1))
 245         {
 246           val -= tree_low_cst (TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1), 1);
 247           lhs = TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0);
 248           continue;
 249         }
 250
 251       lhs = NULL;
 252     }
 253
 254   return ret;
 255 }
 256
 257
 258 /* Called by walk_tree to look for references to va_list variables.  */
 259
 260 static tree
 261 find_va_list_reference (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
 262                         void *data)
 263 {
 264   bitmap va_list_vars = (bitmap) ((struct walk_stmt_info *) data)->info;
 265   tree var = *tp;
 266
 267   if (TREE_CODE (var) == SSA_NAME)
 268     {
 269       if (bitmap_bit_p (va_list_vars, SSA_NAME_VERSION (var)))
 270         return var;
 271     }
 272   else if (TREE_CODE (var) == VAR_DECL)
 273     {
 274       if (bitmap_bit_p (va_list_vars, DECL_UID (var) + num_ssa_names))
 275         return var;
 276     }
 277
 278   return NULL_TREE;
 279 }
 280
 281
 282 /* Helper function of va_list_counter_struct_op.  Compute
 283    cfun->va_list_{g,f}pr_size.  AP is a va_list GPR/FPR counter,
 284    if WRITE_P is true, seen in AP = VAR, otherwise seen in VAR = AP
 285    statement.  GPR_P is true if AP is a GPR counter, false if it is
 286    a FPR counter.  */
 287
 288 static void
 289 va_list_counter_op (struct stdarg_info *si, tree ap, tree var, bool gpr_p,
 290                     bool write_p)
 291 {
 292   unsigned HOST_WIDE_INT increment;
 293
 294   if (si->compute_sizes < 0)
 295     {
 296       si->compute_sizes = 0;
 297       if (si->va_start_count == 1
 298           && reachable_at_most_once (si->bb, si->va_start_bb))
 299         si->compute_sizes = 1;
 300
 301       if (dump_file && (dump_flags & TDF_DETAILS))
 302         fprintf (dump_file,
 303                  "bb%d will %sbe executed at most once for each va_start "
 304                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 305                  si->va_start_bb->index);
 306     }
 307
 308   if (write_p
 309       && si->compute_sizes
 310       && (increment = va_list_counter_bump (si, ap, var, gpr_p)) + 1 > 1)
 311     {
 312       if (gpr_p && cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE)
 313         {
 314           cfun->va_list_gpr_size += increment;
 315           return;
 316         }
 317
 318       if (!gpr_p && cfun->va_list_fpr_size + increment < VA_LIST_MAX_FPR_SIZE)
 319         {
 320           cfun->va_list_fpr_size += increment;
 321           return;
 322         }
 323     }
 324
 325   if (write_p || !si->compute_sizes)
 326     {
 327       if (gpr_p)
 328         cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 329       else
 330         cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
 331     }
 332 }
 333
 334
 335 /* If AP is a va_list GPR/FPR counter, compute cfun->va_list_{g,f}pr_size.
 336    If WRITE_P is true, AP has been seen in AP = VAR assignment, if WRITE_P
 337    is false, AP has been seen in VAR = AP assignment.
 338    Return true if the AP = VAR (resp. VAR = AP) statement is a recognized
 339    va_arg operation that doesn't cause the va_list variable to escape
 340    current function.  */
 341
 342 static bool
 343 va_list_counter_struct_op (struct stdarg_info *si, tree ap, tree var,
 344                            bool write_p)
 345 {
 346   tree base;
 347
 348   if (TREE_CODE (ap) != COMPONENT_REF
 349       || TREE_CODE (TREE_OPERAND (ap, 1)) != FIELD_DECL)
 350     return false;
 351
 352   if (TREE_CODE (var) != SSA_NAME
 353       || bitmap_bit_p (si->va_list_vars, SSA_NAME_VERSION (var)))
 354     return false;
 355
 356   base = get_base_address (ap);
 357   if (TREE_CODE (base) != VAR_DECL
 358       || !bitmap_bit_p (si->va_list_vars, DECL_UID (base) + num_ssa_names))
 359     return false;
 360
 361   if (TREE_OPERAND (ap, 1) == va_list_gpr_counter_field)
 362     va_list_counter_op (si, ap, var, true, write_p);
 363   else if (TREE_OPERAND (ap, 1) == va_list_fpr_counter_field)
 364     va_list_counter_op (si, ap, var, false, write_p);
 365
 366   return true;
 367 }
 368
 369
 370 /* Check for TEM = AP.  Return true if found and the caller shouldn't
 371    search for va_list references in the statement.  */
 372
 373 static bool
 374 va_list_ptr_read (struct stdarg_info *si, tree ap, tree tem)
 375 {
 376   if (TREE_CODE (ap) != VAR_DECL
 377       || !bitmap_bit_p (si->va_list_vars, DECL_UID (ap) + num_ssa_names))
 378     return false;
 379
 380   if (TREE_CODE (tem) != SSA_NAME
 381       || bitmap_bit_p (si->va_list_vars, SSA_NAME_VERSION (tem)))
 382     return false;
 383
 384   if (si->compute_sizes < 0)
 385     {
 386       si->compute_sizes = 0;
 387       if (si->va_start_count == 1
 388           && reachable_at_most_once (si->bb, si->va_start_bb))
 389         si->compute_sizes = 1;
 390
 391       if (dump_file && (dump_flags & TDF_DETAILS))
 392         fprintf (dump_file,
 393                  "bb%d will %sbe executed at most once for each va_start "
 394                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 395                  si->va_start_bb->index);
 396     }
 397
 398   /* For void * or char * va_list types, there is just one counter.
 399      If va_arg is used in a loop, we don't know how many registers need
 400      saving.  */
 401   if (! si->compute_sizes)
 402     return false;
 403
 404   if (va_list_counter_bump (si, ap, tem, true) == HOST_WIDE_INT_M1U)
 405     return false;
 406
 407   /* Note the temporary, as we need to track whether it doesn't escape
 408      the current function.  */
 409   bitmap_set_bit (si->va_list_escape_vars, SSA_NAME_VERSION (tem));
 410
 411   return true;
 412 }
 413
 414
 415 /* Check for:
 416      tem1 = AP;
 417      TEM2 = tem1 + CST;
 418      AP = TEM2;
 419    sequence and update cfun->va_list_gpr_size.  Return true if found.  */
 420
 421 static bool
 422 va_list_ptr_write (struct stdarg_info *si, tree ap, tree tem2)
 423 {
 424   unsigned HOST_WIDE_INT increment;
 425
 426   if (TREE_CODE (ap) != VAR_DECL
 427       || !bitmap_bit_p (si->va_list_vars, DECL_UID (ap) + num_ssa_names))
 428     return false;
 429
 430   if (TREE_CODE (tem2) != SSA_NAME
 431       || bitmap_bit_p (si->va_list_vars, SSA_NAME_VERSION (tem2)))
 432     return false;
 433
 434   if (si->compute_sizes <= 0)
 435     return false;
 436
 437   increment = va_list_counter_bump (si, ap, tem2, true);
 438   if (increment + 1 <= 1)
 439     return false;
 440
 441   if (cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE)
 442     cfun->va_list_gpr_size += increment;
 443   else
 444     cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 445
 446   return true;
 447 }
 448
 449
 450 /* If RHS is X, (some type *) X or X + CST for X a temporary variable
 451    containing value of some va_list variable plus optionally some constant,
 452    either set si->va_list_escapes or add LHS to si->va_list_escape_vars,
 453    depending whether LHS is a function local temporary.  */
 454
 455 static void
 456 check_va_list_escapes (struct stdarg_info *si, tree lhs, tree rhs)
 457 {
 458   if (! POINTER_TYPE_P (TREE_TYPE (rhs)))
 459     return;
 460
 461   if (TREE_CODE (rhs) == SSA_NAME)
 462     {
 463       if (! bitmap_bit_p (si->va_list_escape_vars, SSA_NAME_VERSION (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       tree ptr = TREE_OPERAND (TREE_OPERAND (rhs, 0), 0);
 471       if (! bitmap_bit_p (si->va_list_escape_vars, SSA_NAME_VERSION (ptr)))
 472         return;
 473     }
 474   else
 475     return;
 476
 477   if (TREE_CODE (lhs) != SSA_NAME)
 478     {
 479       si->va_list_escapes = true;
 480       return;
 481     }
 482
 483   if (si->compute_sizes < 0)
 484     {
 485       si->compute_sizes = 0;
 486       if (si->va_start_count == 1
 487           && reachable_at_most_once (si->bb, si->va_start_bb))
 488         si->compute_sizes = 1;
 489
 490       if (dump_file && (dump_flags & TDF_DETAILS))
 491         fprintf (dump_file,
 492                  "bb%d will %sbe executed at most once for each va_start "
 493                  "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ",
 494                  si->va_start_bb->index);
 495     }
 496
 497   /* For void * or char * va_list types, there is just one counter.
 498      If va_arg is used in a loop, we don't know how many registers need
 499      saving.  */
 500   if (! si->compute_sizes)
 501     {
 502       si->va_list_escapes = true;
 503       return;
 504     }
 505
 506   if (va_list_counter_bump (si, si->va_start_ap, lhs, true)
 507       == HOST_WIDE_INT_M1U)
 508     {
 509       si->va_list_escapes = true;
 510       return;
 511     }
 512
 513   bitmap_set_bit (si->va_list_escape_vars, SSA_NAME_VERSION (lhs));
 514 }
 515
 516
 517 /* Check all uses of temporaries from si->va_list_escape_vars bitmap.
 518    Return true if va_list might be escaping.  */
 519
 520 static bool
 521 check_all_va_list_escapes (struct stdarg_info *si)
 522 {
 523   basic_block bb;
 524
 525   FOR_EACH_BB (bb)
 526     {
 527       gimple_stmt_iterator i;
 528
 529       for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
 530         {
 531           tree lhs;
 532           use_operand_p uop;
 533           ssa_op_iter soi;
 534           gimple phi = gsi_stmt (i);
 535
 536           lhs = PHI_RESULT (phi);
 537           if (virtual_operand_p (lhs)
 538               || bitmap_bit_p (si->va_list_escape_vars,
 539                                SSA_NAME_VERSION (lhs)))
 540             continue;
 541
 542           FOR_EACH_PHI_ARG (uop, phi, soi, SSA_OP_USE)
 543             {
 544               tree rhs = USE_FROM_PTR (uop);
 545               if (TREE_CODE (rhs) == SSA_NAME
 546                   && bitmap_bit_p (si->va_list_escape_vars,
 547                                 SSA_NAME_VERSION (rhs)))
 548                 {
 549                   if (dump_file && (dump_flags & TDF_DETAILS))
 550                     {
 551                       fputs ("va_list escapes in ", dump_file);
 552                       print_gimple_stmt (dump_file, phi, 0, dump_flags);
 553                       fputc ('\n', dump_file);
 554                     }
 555                   return true;
 556                 }
 557             }
 558         }
 559
 560       for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
 561         {
 562           gimple stmt = gsi_stmt (i);
 563           tree use;
 564           ssa_op_iter iter;
 565
 566           if (is_gimple_debug (stmt))
 567             continue;
 568
 569           FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES)
 570             {
 571               if (! bitmap_bit_p (si->va_list_escape_vars,
 572                                   SSA_NAME_VERSION (use)))
 573                 continue;
 574
 575               if (is_gimple_assign (stmt))
 576                 {
 577                   tree rhs = gimple_assign_rhs1 (stmt);
 578                   enum tree_code rhs_code = gimple_assign_rhs_code (stmt);
 579
 580                   /* x = *ap_temp;  */
 581                   if (rhs_code == MEM_REF
 582                       && TREE_OPERAND (rhs, 0) == use
 583                       && TYPE_SIZE_UNIT (TREE_TYPE (rhs))
 584                       && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (rhs)), 1)
 585                       && si->offsets[SSA_NAME_VERSION (use)] != -1)
 586                     {
 587                       unsigned HOST_WIDE_INT gpr_size;
 588                       tree access_size = TYPE_SIZE_UNIT (TREE_TYPE (rhs));
 589
 590                       gpr_size = si->offsets[SSA_NAME_VERSION (use)]
 591                                  + tree_low_cst (TREE_OPERAND (rhs, 1), 0)
 592                                  + tree_low_cst (access_size, 1);
 593                       if (gpr_size >= VA_LIST_MAX_GPR_SIZE)
 594                         cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 595                       else if (gpr_size > cfun->va_list_gpr_size)
 596                         cfun->va_list_gpr_size = gpr_size;
 597                       continue;
 598                     }
 599
 600                   /* va_arg sequences may contain
 601                      other_ap_temp = ap_temp;
 602                      other_ap_temp = ap_temp + constant;
 603                      other_ap_temp = (some_type *) ap_temp;
 604                      ap = ap_temp;
 605                      statements.  */
 606                   if (rhs == use
 607                       && ((rhs_code == POINTER_PLUS_EXPR
 608                            && (TREE_CODE (gimple_assign_rhs2 (stmt))
 609                                == INTEGER_CST))
 610                           || gimple_assign_cast_p (stmt)
 611                           || (get_gimple_rhs_class (rhs_code)
 612                               == GIMPLE_SINGLE_RHS)))
 613                     {
 614                       tree lhs = gimple_assign_lhs (stmt);
 615
 616                       if (TREE_CODE (lhs) == SSA_NAME
 617                           && bitmap_bit_p (si->va_list_escape_vars,
 618                                            SSA_NAME_VERSION (lhs)))
 619                         continue;
 620
 621                       if (TREE_CODE (lhs) == VAR_DECL
 622                           && bitmap_bit_p (si->va_list_vars,
 623                                            DECL_UID (lhs) + num_ssa_names))
 624                         continue;
 625                     }
 626                   else if (rhs_code == ADDR_EXPR
 627                            && TREE_CODE (TREE_OPERAND (rhs, 0)) == MEM_REF
 628                            && TREE_OPERAND (TREE_OPERAND (rhs, 0), 0) == use)
 629                     {
 630                       tree lhs = gimple_assign_lhs (stmt);
 631
 632                       if (bitmap_bit_p (si->va_list_escape_vars,
 633                                         SSA_NAME_VERSION (lhs)))
 634                         continue;
 635                     }
 636                 }
 637
 638               if (dump_file && (dump_flags & TDF_DETAILS))
 639                 {
 640                   fputs ("va_list escapes in ", dump_file);
 641                   print_gimple_stmt (dump_file, stmt, 0, dump_flags);
 642                   fputc ('\n', dump_file);
 643                 }
 644               return true;
 645             }
 646         }
 647     }
 648
 649   return false;
 650 }
 651
 652
 653 /* Return true if this optimization pass should be done.
 654    It makes only sense for stdarg functions.  */
 655
 656 static bool
 657 gate_optimize_stdarg (void)
 658 {
 659   /* This optimization is only for stdarg functions.  */
 660   return cfun->stdarg != 0;
 661 }
 662
 663
 664 /* Entry point to the stdarg optimization pass.  */
 665
 666 static unsigned int
 667 execute_optimize_stdarg (void)
 668 {
 669   basic_block bb;
 670   bool va_list_escapes = false;
 671   bool va_list_simple_ptr;
 672   struct stdarg_info si;
 673   struct walk_stmt_info wi;
 674   const char *funcname = NULL;
 675   tree cfun_va_list;
 676
 677   cfun->va_list_gpr_size = 0;
 678   cfun->va_list_fpr_size = 0;
 679   memset (&si, 0, sizeof (si));
 680   si.va_list_vars = BITMAP_ALLOC (NULL);
 681   si.va_list_escape_vars = BITMAP_ALLOC (NULL);
 682
 683   if (dump_file)
 684     funcname = lang_hooks.decl_printable_name (current_function_decl, 2);
 685
 686   cfun_va_list = targetm.fn_abi_va_list (cfun->decl);
 687   va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list)
 688                        && (TREE_TYPE (cfun_va_list) == void_type_node
 689                            || TREE_TYPE (cfun_va_list) == char_type_node);
 690   gcc_assert (is_gimple_reg_type (cfun_va_list) == va_list_simple_ptr);
 691
 692   FOR_EACH_BB (bb)
 693     {
 694       gimple_stmt_iterator i;
 695
 696       for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
 697         {
 698           gimple stmt = gsi_stmt (i);
 699           tree callee, ap;
 700
 701           if (!is_gimple_call (stmt))
 702             continue;
 703
 704           callee = gimple_call_fndecl (stmt);
 705           if (!callee
 706               || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
 707             continue;
 708
 709           switch (DECL_FUNCTION_CODE (callee))
 710             {
 711             case BUILT_IN_VA_START:
 712               break;
 713               /* If old style builtins are used, don't optimize anything.  */
 714             case BUILT_IN_SAVEREGS:
 715             case BUILT_IN_NEXT_ARG:
 716               va_list_escapes = true;
 717               continue;
 718             default:
 719               continue;
 720             }
 721
 722           si.va_start_count++;
 723           ap = gimple_call_arg (stmt, 0);
 724
 725           if (TREE_CODE (ap) != ADDR_EXPR)
 726             {
 727               va_list_escapes = true;
 728               break;
 729             }
 730           ap = TREE_OPERAND (ap, 0);
 731           if (TREE_CODE (ap) == ARRAY_REF)
 732             {
 733               if (! integer_zerop (TREE_OPERAND (ap, 1)))
 734                 {
 735                   va_list_escapes = true;
 736                   break;
 737                 }
 738               ap = TREE_OPERAND (ap, 0);
 739             }
 740           if (TYPE_MAIN_VARIANT (TREE_TYPE (ap))
 741               != TYPE_MAIN_VARIANT (targetm.fn_abi_va_list (cfun->decl))
 742               || TREE_CODE (ap) != VAR_DECL)
 743             {
 744               va_list_escapes = true;
 745               break;
 746             }
 747
 748           if (is_global_var (ap))
 749             {
 750               va_list_escapes = true;
 751               break;
 752             }
 753
 754           bitmap_set_bit (si.va_list_vars, DECL_UID (ap) + num_ssa_names);
 755
 756           /* VA_START_BB and VA_START_AP will be only used if there is just
 757              one va_start in the function.  */
 758           si.va_start_bb = bb;
 759           si.va_start_ap = ap;
 760         }
 761
 762       if (va_list_escapes)
 763         break;
 764     }
 765
 766   /* If there were no va_start uses in the function, there is no need to
 767      save anything.  */
 768   if (si.va_start_count == 0)
 769     goto finish;
 770
 771   /* If some va_list arguments weren't local, we can't optimize.  */
 772   if (va_list_escapes)
 773     goto finish;
 774
 775   /* For void * or char * va_list, something useful can be done only
 776      if there is just one va_start.  */
 777   if (va_list_simple_ptr && si.va_start_count > 1)
 778     {
 779       va_list_escapes = true;
 780       goto finish;
 781     }
 782
 783   /* For struct * va_list, if the backend didn't tell us what the counter fields
 784      are, there is nothing more we can do.  */
 785   if (!va_list_simple_ptr
 786       && va_list_gpr_counter_field == NULL_TREE
 787       && va_list_fpr_counter_field == NULL_TREE)
 788     {
 789       va_list_escapes = true;
 790       goto finish;
 791     }
 792
 793   /* For void * or char * va_list there is just one counter
 794      (va_list itself).  Use VA_LIST_GPR_SIZE for it.  */
 795   if (va_list_simple_ptr)
 796     cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
 797
 798   calculate_dominance_info (CDI_DOMINATORS);
 799   memset (&wi, 0, sizeof (wi));
 800   wi.info = si.va_list_vars;
 801
 802   FOR_EACH_BB (bb)
 803     {
 804       gimple_stmt_iterator i;
 805
 806       si.compute_sizes = -1;
 807       si.bb = bb;
 808
 809       /* For va_list_simple_ptr, we have to check PHI nodes too.  We treat
 810          them as assignments for the purpose of escape analysis.  This is
 811          not needed for non-simple va_list because virtual phis don't perform
 812          any real data movement.  */
 813       if (va_list_simple_ptr)
 814         {
 815           tree lhs, rhs;
 816           use_operand_p uop;
 817           ssa_op_iter soi;
 818
 819           for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
 820             {
 821               gimple phi = gsi_stmt (i);
 822               lhs = PHI_RESULT (phi);
 823
 824               if (virtual_operand_p (lhs))
 825                 continue;
 826
 827               FOR_EACH_PHI_ARG (uop, phi, soi, SSA_OP_USE)
 828                 {
 829                   rhs = USE_FROM_PTR (uop);
 830                   if (va_list_ptr_read (&si, rhs, lhs))
 831                     continue;
 832                   else if (va_list_ptr_write (&si, lhs, rhs))
 833                     continue;
 834                   else
 835                     check_va_list_escapes (&si, lhs, rhs);
 836
 837                   if (si.va_list_escapes)
 838                     {
 839                       if (dump_file && (dump_flags & TDF_DETAILS))
 840                         {
 841                           fputs ("va_list escapes in ", dump_file);
 842                           print_gimple_stmt (dump_file, phi, 0, dump_flags);
 843                           fputc ('\n', dump_file);
 844                         }
 845                       va_list_escapes = true;
 846                     }
 847                 }
 848             }
 849         }
 850
 851       for (i = gsi_start_bb (bb);
 852            !gsi_end_p (i) && !va_list_escapes;
 853            gsi_next (&i))
 854         {
 855           gimple stmt = gsi_stmt (i);
 856
 857           /* Don't look at __builtin_va_{start,end}, they are ok.  */
 858           if (is_gimple_call (stmt))
 859             {
 860               tree callee = gimple_call_fndecl (stmt);
 861
 862               if (callee
 863                   && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
 864                   && (DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_START
 865                       || DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_END))
 866                 continue;
 867             }
 868
 869           if (is_gimple_assign (stmt))
 870             {
 871               tree lhs = gimple_assign_lhs (stmt);
 872               tree rhs = gimple_assign_rhs1 (stmt);
 873
 874               if (va_list_simple_ptr)
 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 tem = ap.  */
 884                       else if (va_list_ptr_read (&si, rhs, lhs))
 885                         continue;
 886
 887                       /* Check for the last insn in:
 888                          tem1 = ap;
 889                          tem2 = tem1 + CST;
 890                          ap = tem2;
 891                          sequence.  */
 892                       else if (va_list_ptr_write (&si, lhs, rhs))
 893                         continue;
 894                     }
 895
 896                   if ((gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
 897                        && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST)
 898                       || CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt))
 899                       || (get_gimple_rhs_class (gimple_assign_rhs_code (stmt))
 900                           == GIMPLE_SINGLE_RHS))
 901                     check_va_list_escapes (&si, lhs, rhs);
 902                 }
 903               else
 904                 {
 905                   if (get_gimple_rhs_class (gimple_assign_rhs_code (stmt))
 906                       == GIMPLE_SINGLE_RHS)
 907                     {
 908                       /* Check for ap ={v} {}.  */
 909                       if (TREE_CLOBBER_P (rhs))
 910                         continue;
 911
 912                       /* Check for ap[0].field = temp.  */
 913                       else if (va_list_counter_struct_op (&si, lhs, rhs, true))
 914                         continue;
 915
 916                       /* Check for temp = ap[0].field.  */
 917                       else if (va_list_counter_struct_op (&si, rhs, lhs,
 918                                                           false))
 919                         continue;
 920                     }
 921
 922                   /* Do any architecture specific checking.  */
 923                   if (targetm.stdarg_optimize_hook
 924                       && targetm.stdarg_optimize_hook (&si, stmt))
 925                     continue;
 926                 }
 927             }
 928           else if (is_gimple_debug (stmt))
 929             continue;
 930
 931           /* All other uses of va_list are either va_copy (that is not handled
 932              in this optimization), taking address of va_list variable or
 933              passing va_list to other functions (in that case va_list might
 934              escape the function and therefore va_start needs to set it up
 935              fully), or some unexpected use of va_list.  None of these should
 936              happen in a gimplified VA_ARG_EXPR.  */
 937           if (si.va_list_escapes
 938               || walk_gimple_op (stmt, find_va_list_reference, &wi))
 939             {
 940               if (dump_file && (dump_flags & TDF_DETAILS))
 941                 {
 942                   fputs ("va_list escapes in ", dump_file);
 943                   print_gimple_stmt (dump_file, stmt, 0, dump_flags);
 944                   fputc ('\n', dump_file);
 945                 }
 946               va_list_escapes = true;
 947             }
 948         }
 949
 950       if (va_list_escapes)
 951         break;
 952     }
 953
 954   if (! va_list_escapes
 955       && va_list_simple_ptr
 956       && ! bitmap_empty_p (si.va_list_escape_vars)
 957       && check_all_va_list_escapes (&si))
 958     va_list_escapes = true;
 959
 960 finish:
 961   if (va_list_escapes)
 962     {
 963       cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
 964       cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE;
 965     }
 966   BITMAP_FREE (si.va_list_vars);
 967   BITMAP_FREE (si.va_list_escape_vars);
 968   free (si.offsets);
 969   if (dump_file)
 970     {
 971       fprintf (dump_file, "%s: va_list escapes %d, needs to save ",
 972                funcname, (int) va_list_escapes);
 973       if (cfun->va_list_gpr_size >= VA_LIST_MAX_GPR_SIZE)
 974         fputs ("all", dump_file);
 975       else
 976         fprintf (dump_file, "%d", cfun->va_list_gpr_size);
 977       fputs (" GPR units and ", dump_file);
 978       if (cfun->va_list_fpr_size >= VA_LIST_MAX_FPR_SIZE)
 979         fputs ("all", dump_file);
 980       else
 981         fprintf (dump_file, "%d", cfun->va_list_fpr_size);
 982       fputs (" FPR units.\n", dump_file);
 983     }
 984   return 0;
 985 }
 986
 987
 988 namespace {
 989
 990 const pass_data pass_data_stdarg =
 991 {
 992   GIMPLE_PASS, /* type */
 993   "stdarg", /* name */
 994   OPTGROUP_NONE, /* optinfo_flags */
 995   true, /* has_gate */
 996   true, /* has_execute */
 997   TV_NONE, /* tv_id */
 998   ( PROP_cfg | PROP_ssa ), /* properties_required */
 999   0, /* properties_provided */
1000   0, /* properties_destroyed */
1001   0, /* todo_flags_start */
1002   0, /* todo_flags_finish */
1003 };
1004
1005 class pass_stdarg : public gimple_opt_pass
1006 {
1007 public:
1008   pass_stdarg(gcc::context *ctxt)
1009     : gimple_opt_pass(pass_data_stdarg, ctxt)
1010   {}
1011
1012   /* opt_pass methods: */
1013   bool gate () { return gate_optimize_stdarg (); }
1014   unsigned int execute () { return execute_optimize_stdarg (); }
1015
1016 }; // class pass_stdarg
1017
1018 } // anon namespace
1019
1020 gimple_opt_pass *
1021 make_pass_stdarg (gcc::context *ctxt)
1022 {
1023   return new pass_stdarg (ctxt);
1024 }