gcc/ada/utils2.c

   1 /****************************************************************************
   2  *                                                                          *
   3  *                         GNAT COMPILER COMPONENTS                         *
   4  *                                                                          *
   5  *                               U T I L S 2                                *
   6  *                                                                          *
   7  *                          C Implementation File                           *
   8  *                                                                          *
   9  *                                                                          *
  10  *          Copyright (C) 1992-2002, Free Software Foundation, Inc.         *
  11  *                                                                          *
  12  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  13  * terms of the  GNU General Public License as published  by the Free Soft- *
  14  * ware  Foundation;  either version 2,  or (at your option) any later ver- *
  15  * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
  16  * OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY *
  17  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License *
  18  * for  more details.  You should have  received  a copy of the GNU General *
  19  * Public License  distributed with GNAT;  see file COPYING.  If not, write *
  20  * to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, *
  21  * MA 02111-1307, USA.                                                      *
  22  *                                                                          *
  23  * GNAT was originally developed  by the GNAT team at  New York University. *
  24  * Extensive contributions were provided by Ada Core Technologies Inc.      *
  25  *                                                                          *
  26  ****************************************************************************/
  27
  28 #include "config.h"
  29 #include "system.h"
  30 #include "coretypes.h"
  31 #include "tm.h"
  32 #include "tree.h"
  33 #include "flags.h"
  34 #include "ada.h"
  35 #include "types.h"
  36 #include "atree.h"
  37 #include "stringt.h"
  38 #include "uintp.h"
  39 #include "fe.h"
  40 #include "elists.h"
  41 #include "nlists.h"
  42 #include "sinfo.h"
  43 #include "einfo.h"
  44 #include "ada-tree.h"
  45 #include "gigi.h"
  46
  47 static tree find_common_type            PARAMS ((tree, tree));
  48 static int contains_save_expr_p         PARAMS ((tree));
  49 static tree contains_null_expr          PARAMS ((tree));
  50 static tree compare_arrays              PARAMS ((tree, tree, tree));
  51 static tree nonbinary_modular_operation PARAMS ((enum tree_code, tree,
  52                                                 tree, tree));
  53 static tree build_simple_component_ref  PARAMS ((tree, tree, tree));
  54 \f
  55 /* Prepare expr to be an argument of a TRUTH_NOT_EXPR or other logical
  56    operation.
  57
  58    This preparation consists of taking the ordinary representation of
  59    an expression expr and producing a valid tree boolean expression
  60    describing whether expr is nonzero. We could simply always do
  61
  62       build_binary_op (NE_EXPR, expr, integer_zero_node, 1),
  63
  64    but we optimize comparisons, &&, ||, and !.
  65
  66    The resulting type should always be the same as the input type.
  67    This function is simpler than the corresponding C version since
  68    the only possible operands will be things of Boolean type.  */
  69
  70 tree
  71 gnat_truthvalue_conversion (expr)
  72      tree expr;
  73 {
  74   tree type = TREE_TYPE (expr);
  75
  76   switch (TREE_CODE (expr))
  77     {
  78     case EQ_EXPR:  case NE_EXPR: case LE_EXPR: case GE_EXPR:
  79     case LT_EXPR:  case GT_EXPR:
  80     case TRUTH_ANDIF_EXPR:
  81     case TRUTH_ORIF_EXPR:
  82     case TRUTH_AND_EXPR:
  83     case TRUTH_OR_EXPR:
  84     case TRUTH_XOR_EXPR:
  85     case ERROR_MARK:
  86       return expr;
  87
  88     case COND_EXPR:
  89       /* Distribute the conversion into the arms of a COND_EXPR.  */
  90       return fold
  91         (build (COND_EXPR, type, TREE_OPERAND (expr, 0),
  92                 gnat_truthvalue_conversion (TREE_OPERAND (expr, 1)),
  93                 gnat_truthvalue_conversion (TREE_OPERAND (expr, 2))));
  94
  95     case WITH_RECORD_EXPR:
  96       return build (WITH_RECORD_EXPR, type,
  97                     gnat_truthvalue_conversion (TREE_OPERAND (expr, 0)),
  98                     TREE_OPERAND (expr, 1));
  99
 100     default:
 101       return build_binary_op (NE_EXPR, type, expr,
 102                               convert (type, integer_zero_node));
 103     }
 104 }
 105 \f
 106 /* Return the base type of TYPE.  */
 107
 108 tree
 109 get_base_type (type)
 110      tree type;
 111 {
 112   if (TREE_CODE (type) == RECORD_TYPE
 113       && TYPE_LEFT_JUSTIFIED_MODULAR_P (type))
 114     type = TREE_TYPE (TYPE_FIELDS (type));
 115
 116   while (TREE_TYPE (type) != 0
 117          && (TREE_CODE (type) == INTEGER_TYPE
 118              || TREE_CODE (type) == REAL_TYPE))
 119     type = TREE_TYPE (type);
 120
 121   return type;
 122 }
 123
 124 /* Likewise, but only return types known to the Ada source.  */
 125 tree
 126 get_ada_base_type (type)
 127      tree type;
 128 {
 129   while (TREE_TYPE (type) != 0
 130          && (TREE_CODE (type) == INTEGER_TYPE
 131              || TREE_CODE (type) == REAL_TYPE)
 132          && ! TYPE_EXTRA_SUBTYPE_P (type))
 133     type = TREE_TYPE (type);
 134
 135   return type;
 136 }
 137 \f
 138 /* EXP is a GCC tree representing an address.  See if we can find how
 139    strictly the object at that address is aligned.   Return that alignment
 140    in bits.  If we don't know anything about the alignment, return 0.
 141    We do not go merely by type information here since the check on
 142    N_Validate_Unchecked_Alignment does that.  */
 143
 144 unsigned int
 145 known_alignment (exp)
 146      tree exp;
 147 {
 148   unsigned int lhs, rhs;
 149
 150   switch (TREE_CODE (exp))
 151     {
 152     case CONVERT_EXPR:
 153     case NOP_EXPR:
 154     case NON_LVALUE_EXPR:
 155       /* Conversions between pointers and integers don't change the alignment
 156          of the underlying object.  */
 157       return known_alignment (TREE_OPERAND (exp, 0));
 158
 159     case PLUS_EXPR:
 160     case MINUS_EXPR:
 161       /* If two address are added, the alignment of the result is the
 162          minimum of the two aligments.  */
 163       lhs = known_alignment (TREE_OPERAND (exp, 0));
 164       rhs = known_alignment (TREE_OPERAND (exp, 1));
 165       return MIN (lhs, rhs);
 166
 167     case INTEGER_CST:
 168       /* The first part of this represents the lowest bit in the constant,
 169          but is it in bytes, not bits.  */
 170       return MIN (BITS_PER_UNIT
 171                   * (TREE_INT_CST_LOW (exp) & - TREE_INT_CST_LOW (exp)),
 172                   BIGGEST_ALIGNMENT);
 173
 174     case MULT_EXPR:
 175       /* If we know the alignment of just one side, use it.  Otherwise,
 176          use the product of the alignments.  */
 177       lhs = known_alignment (TREE_OPERAND (exp, 0));
 178       rhs = known_alignment (TREE_OPERAND (exp, 1));
 179       if (lhs == 0 || rhs == 0)
 180         return MIN (BIGGEST_ALIGNMENT, MAX (lhs, rhs));
 181
 182       return MIN (BIGGEST_ALIGNMENT, lhs * rhs);
 183
 184     case ADDR_EXPR:
 185       return expr_align (TREE_OPERAND (exp, 0));
 186
 187     default:
 188       return 0;
 189     }
 190 }
 191 \f
 192 /* We have a comparison or assignment operation on two types, T1 and T2,
 193    which are both either array types or both record types.
 194    Return the type that both operands should be converted to, if any.
 195    Otherwise return zero.  */
 196
 197 static tree
 198 find_common_type (t1, t2)
 199      tree t1, t2;
 200 {
 201   /* If either type is non-BLKmode, use it.  Note that we know that we will
 202      not have any alignment problems since if we did the non-BLKmode
 203      type could not have been used.  */
 204   if (TYPE_MODE (t1) != BLKmode)
 205     return t1;
 206   else if (TYPE_MODE (t2) != BLKmode)
 207     return t2;
 208
 209   /* Otherwise, return the type that has a constant size.  */
 210   if (TREE_CONSTANT (TYPE_SIZE (t1)))
 211     return t1;
 212   else if (TREE_CONSTANT (TYPE_SIZE (t2)))
 213     return t2;
 214
 215   /* In this case, both types have variable size.  It's probably
 216      best to leave the "type mismatch" because changing it could
 217      case a bad self-referential reference.  */
 218   return 0;
 219 }
 220 \f
 221 /* See if EXP contains a SAVE_EXPR in a position where we would
 222    normally put it.
 223
 224    ??? This is a real kludge, but is probably the best approach short
 225    of some very general solution.  */
 226
 227 static int
 228 contains_save_expr_p (exp)
 229      tree exp;
 230 {
 231   switch (TREE_CODE (exp))
 232     {
 233     case SAVE_EXPR:
 234       return 1;
 235
 236     case ADDR_EXPR:  case INDIRECT_REF:
 237     case COMPONENT_REF:
 238     case NOP_EXPR:  case CONVERT_EXPR: case VIEW_CONVERT_EXPR:
 239       return contains_save_expr_p (TREE_OPERAND (exp, 0));
 240
 241     case CONSTRUCTOR:
 242       return (CONSTRUCTOR_ELTS (exp) != 0
 243               && contains_save_expr_p (CONSTRUCTOR_ELTS (exp)));
 244
 245     case TREE_LIST:
 246       return (contains_save_expr_p (TREE_VALUE (exp))
 247               || (TREE_CHAIN (exp) != 0
 248                   && contains_save_expr_p (TREE_CHAIN (exp))));
 249
 250     default:
 251       return 0;
 252     }
 253 }
 254 \f
 255 /* See if EXP contains a NULL_EXPR in an expression we use for sizes. Return
 256    it if so.  This is used to detect types whose sizes involve computations
 257    that are known to raise Constraint_Error.  */
 258
 259 static tree
 260 contains_null_expr (exp)
 261      tree exp;
 262 {
 263   tree tem;
 264
 265   if (TREE_CODE (exp) == NULL_EXPR)
 266     return exp;
 267
 268   switch (TREE_CODE_CLASS (TREE_CODE (exp)))
 269     {
 270     case '1':
 271       return contains_null_expr (TREE_OPERAND (exp, 0));
 272
 273     case '<':  case '2':
 274       tem = contains_null_expr (TREE_OPERAND (exp, 0));
 275       if (tem != 0)
 276         return tem;
 277
 278       return contains_null_expr (TREE_OPERAND (exp, 1));
 279
 280     case 'e':
 281       switch (TREE_CODE (exp))
 282         {
 283         case SAVE_EXPR:
 284           return contains_null_expr (TREE_OPERAND (exp, 0));
 285
 286         case COND_EXPR:
 287           tem = contains_null_expr (TREE_OPERAND (exp, 0));
 288           if (tem != 0)
 289             return tem;
 290
 291           tem = contains_null_expr (TREE_OPERAND (exp, 1));
 292           if (tem != 0)
 293             return tem;
 294
 295           return contains_null_expr (TREE_OPERAND (exp, 2));
 296
 297         default:
 298           return 0;
 299         }
 300
 301     default:
 302       return 0;
 303     }
 304 }
 305 \f
 306 /* Return an expression tree representing an equality comparison of
 307    A1 and A2, two objects of ARRAY_TYPE.  The returned expression should
 308    be of type RESULT_TYPE
 309
 310    Two arrays are equal in one of two ways: (1) if both have zero length
 311    in some dimension (not necessarily the same dimension) or (2) if the
 312    lengths in each dimension are equal and the data is equal.  We perform the
 313    length tests in as efficient a manner as possible.  */
 314
 315 static tree
 316 compare_arrays (result_type, a1, a2)
 317      tree a1, a2;
 318      tree result_type;
 319 {
 320   tree t1 = TREE_TYPE (a1);
 321   tree t2 = TREE_TYPE (a2);
 322   tree result = convert (result_type, integer_one_node);
 323   tree a1_is_null = convert (result_type, integer_zero_node);
 324   tree a2_is_null = convert (result_type, integer_zero_node);
 325   int length_zero_p = 0;
 326
 327   /* Process each dimension separately and compare the lengths.  If any
 328      dimension has a size known to be zero, set SIZE_ZERO_P to 1 to
 329      suppress the comparison of the data.  */
 330   while (TREE_CODE (t1) == ARRAY_TYPE && TREE_CODE (t2) == ARRAY_TYPE)
 331     {
 332       tree lb1 = TYPE_MIN_VALUE (TYPE_DOMAIN (t1));
 333       tree ub1 = TYPE_MAX_VALUE (TYPE_DOMAIN (t1));
 334       tree lb2 = TYPE_MIN_VALUE (TYPE_DOMAIN (t2));
 335       tree ub2 = TYPE_MAX_VALUE (TYPE_DOMAIN (t2));
 336       tree bt = get_base_type (TREE_TYPE (lb1));
 337       tree length1 = fold (build (MINUS_EXPR, bt, ub1, lb1));
 338       tree length2 = fold (build (MINUS_EXPR, bt, ub2, lb2));
 339       tree nbt;
 340       tree tem;
 341       tree comparison, this_a1_is_null, this_a2_is_null;
 342
 343       /* If the length of the first array is a constant, swap our operands
 344          unless the length of the second array is the constant zero.
 345          Note that we have set the `length' values to the length - 1.  */
 346       if (TREE_CODE (length1) == INTEGER_CST
 347           && ! integer_zerop (fold (build (PLUS_EXPR, bt, length2,
 348                                            convert (bt, integer_one_node)))))
 349         {
 350           tem = a1, a1 = a2, a2 = tem;
 351           tem = t1, t1 = t2, t2 = tem;
 352           tem = lb1, lb1 = lb2, lb2 = tem;
 353           tem = ub1, ub1 = ub2, ub2 = tem;
 354           tem = length1, length1 = length2, length2 = tem;
 355           tem = a1_is_null, a1_is_null = a2_is_null, a2_is_null = tem;
 356         }
 357
 358       /* If the length of this dimension in the second array is the constant
 359          zero, we can just go inside the original bounds for the first
 360          array and see if last < first.  */
 361       if (integer_zerop (fold (build (PLUS_EXPR, bt, length2,
 362                                       convert (bt, integer_one_node)))))
 363         {
 364           tree ub = TYPE_MAX_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (t1)));
 365           tree lb = TYPE_MIN_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (t1)));
 366
 367           comparison = build_binary_op (LT_EXPR, result_type, ub, lb);
 368
 369           if (contains_placeholder_p (comparison))
 370             comparison = build (WITH_RECORD_EXPR, result_type,
 371                                 comparison, a1);
 372           if (contains_placeholder_p (length1))
 373             length1 = build (WITH_RECORD_EXPR, bt, length1, a1);
 374
 375           length_zero_p = 1;
 376
 377           this_a1_is_null = comparison;
 378           this_a2_is_null = convert (result_type, integer_one_node);
 379         }
 380
 381       /* If the length is some other constant value, we know that the
 382          this dimension in the first array cannot be superflat, so we
 383          can just use its length from the actual stored bounds.  */
 384       else if (TREE_CODE (length2) == INTEGER_CST)
 385         {
 386           ub1 = TYPE_MAX_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (t1)));
 387           lb1 = TYPE_MIN_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (t1)));
 388           ub2 = TYPE_MAX_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (t2)));
 389           lb2 = TYPE_MIN_VALUE (TYPE_INDEX_TYPE (TYPE_DOMAIN (t2)));
 390           nbt = get_base_type (TREE_TYPE (ub1));
 391
 392           comparison
 393             = build_binary_op (EQ_EXPR, result_type,
 394                                build_binary_op (MINUS_EXPR, nbt, ub1, lb1),
 395                                build_binary_op (MINUS_EXPR, nbt, ub2, lb2));
 396
 397           /* Note that we know that UB2 and LB2 are constant and hence
 398              cannot contain a PLACEHOLDER_EXPR.  */
 399
 400           if (contains_placeholder_p (comparison))
 401             comparison = build (WITH_RECORD_EXPR, result_type, comparison, a1);
 402           if (contains_placeholder_p (length1))
 403             length1 = build (WITH_RECORD_EXPR, bt, length1, a1);
 404
 405           this_a1_is_null = build_binary_op (LT_EXPR, result_type, ub1, lb1);
 406           this_a2_is_null = convert (result_type, integer_zero_node);
 407         }
 408
 409       /* Otherwise compare the computed lengths.  */
 410       else
 411         {
 412           if (contains_placeholder_p (length1))
 413             length1 = build (WITH_RECORD_EXPR, bt, length1, a1);
 414           if (contains_placeholder_p (length2))
 415             length2 = build (WITH_RECORD_EXPR, bt, length2, a2);
 416
 417           comparison
 418             = build_binary_op (EQ_EXPR, result_type, length1, length2);
 419
 420           this_a1_is_null
 421             = build_binary_op (LT_EXPR, result_type, length1,
 422                                convert (bt, integer_zero_node));
 423           this_a2_is_null
 424             = build_binary_op (LT_EXPR, result_type, length2,
 425                                convert (bt, integer_zero_node));
 426         }
 427
 428       result = build_binary_op (TRUTH_ANDIF_EXPR, result_type,
 429                                 result, comparison);
 430
 431       a1_is_null = build_binary_op (TRUTH_ORIF_EXPR, result_type,
 432                                     this_a1_is_null, a1_is_null);
 433       a2_is_null = build_binary_op (TRUTH_ORIF_EXPR, result_type,
 434                                     this_a2_is_null, a2_is_null);
 435
 436       t1 = TREE_TYPE (t1);
 437       t2 = TREE_TYPE (t2);
 438     }
 439
 440   /* Unless the size of some bound is known to be zero, compare the
 441      data in the array.  */
 442   if (! length_zero_p)
 443     {
 444       tree type = find_common_type (TREE_TYPE (a1), TREE_TYPE (a2));
 445
 446       if (type != 0)
 447         a1 = convert (type, a1), a2 = convert (type, a2);
 448
 449
 450       result = build_binary_op (TRUTH_ANDIF_EXPR, result_type, result,
 451                                 fold (build (EQ_EXPR, result_type, a1, a2)));
 452
 453     }
 454
 455   /* The result is also true if both sizes are zero.  */
 456   result = build_binary_op (TRUTH_ORIF_EXPR, result_type,
 457                             build_binary_op (TRUTH_ANDIF_EXPR, result_type,
 458                                              a1_is_null, a2_is_null),
 459                             result);
 460
 461   /* If either operand contains SAVE_EXPRs, they have to be evaluated before
 462      starting the comparison above since the place it would be otherwise
 463      evaluated would be wrong.  */
 464
 465   if (contains_save_expr_p (a1))
 466     result = build (COMPOUND_EXPR, result_type, a1, result);
 467
 468   if (contains_save_expr_p (a2))
 469     result = build (COMPOUND_EXPR, result_type, a2, result);
 470
 471   return result;
 472 }
 473 \f
 474 /* Compute the result of applying OP_CODE to LHS and RHS, where both are of
 475    type TYPE.  We know that TYPE is a modular type with a nonbinary
 476    modulus.  */
 477
 478 static tree
 479 nonbinary_modular_operation (op_code, type, lhs, rhs)
 480      enum tree_code op_code;
 481      tree type;
 482      tree lhs, rhs;
 483 {
 484   tree modulus = TYPE_MODULUS (type);
 485   unsigned int needed_precision = tree_floor_log2 (modulus) + 1;
 486   unsigned int precision;
 487   int unsignedp = 1;
 488   tree op_type = type;
 489   tree result;
 490
 491   /* If this is an addition of a constant, convert it to a subtraction
 492      of a constant since we can do that faster.  */
 493   if (op_code == PLUS_EXPR && TREE_CODE (rhs) == INTEGER_CST)
 494     rhs = fold (build (MINUS_EXPR, type, modulus, rhs)), op_code = MINUS_EXPR;
 495
 496   /* For the logical operations, we only need PRECISION bits.  For
 497      addition and subraction, we need one more and for multiplication we
 498      need twice as many.  But we never want to make a size smaller than
 499      our size. */
 500   if (op_code == PLUS_EXPR || op_code == MINUS_EXPR)
 501     needed_precision += 1;
 502   else if (op_code == MULT_EXPR)
 503     needed_precision *= 2;
 504
 505   precision = MAX (needed_precision, TYPE_PRECISION (op_type));
 506
 507   /* Unsigned will do for everything but subtraction.  */
 508   if (op_code == MINUS_EXPR)
 509     unsignedp = 0;
 510
 511   /* If our type is the wrong signedness or isn't wide enough, make a new
 512      type and convert both our operands to it.  */
 513   if (TYPE_PRECISION (op_type) < precision
 514       || TREE_UNSIGNED (op_type) != unsignedp)
 515     {
 516       /* Copy the node so we ensure it can be modified to make it modular.  */
 517       op_type = copy_node (gnat_type_for_size (precision, unsignedp));
 518       modulus = convert (op_type, modulus);
 519       SET_TYPE_MODULUS (op_type, modulus);
 520       TYPE_MODULAR_P (op_type) = 1;
 521       lhs = convert (op_type, lhs);
 522       rhs = convert (op_type, rhs);
 523     }
 524
 525   /* Do the operation, then we'll fix it up.  */
 526   result = fold (build (op_code, op_type, lhs, rhs));
 527
 528   /* For multiplication, we have no choice but to do a full modulus
 529      operation.  However, we want to do this in the narrowest
 530      possible size.  */
 531   if (op_code == MULT_EXPR)
 532     {
 533       tree div_type = copy_node (gnat_type_for_size (needed_precision, 1));
 534       modulus = convert (div_type, modulus);
 535       SET_TYPE_MODULUS (div_type, modulus);
 536       TYPE_MODULAR_P (div_type) = 1;
 537       result = convert (op_type,
 538                         fold (build (TRUNC_MOD_EXPR, div_type,
 539                                      convert (div_type, result), modulus)));
 540     }
 541
 542   /* For subtraction, add the modulus back if we are negative.  */
 543   else if (op_code == MINUS_EXPR)
 544     {
 545       result = save_expr (result);
 546       result = fold (build (COND_EXPR, op_type,
 547                             build (LT_EXPR, integer_type_node, result,
 548                                    convert (op_type, integer_zero_node)),
 549                             fold (build (PLUS_EXPR, op_type,
 550                                          result, modulus)),
 551                             result));
 552     }
 553
 554   /* For the other operations, subtract the modulus if we are >= it.  */
 555   else
 556     {
 557       result = save_expr (result);
 558       result = fold (build (COND_EXPR, op_type,
 559                             build (GE_EXPR, integer_type_node,
 560                                    result, modulus),
 561                             fold (build (MINUS_EXPR, op_type,
 562                                          result, modulus)),
 563                             result));
 564     }
 565
 566   return convert (type, result);
 567 }
 568 \f
 569 /* Make a binary operation of kind OP_CODE.  RESULT_TYPE is the type
 570    desired for the result.  Usually the operation is to be performed
 571    in that type.  For MODIFY_EXPR and ARRAY_REF, RESULT_TYPE may be 0
 572    in which case the type to be used will be derived from the operands.
 573
 574    This function is very much unlike the ones for C and C++ since we
 575    have already done any type conversion and matching required.  All we
 576    have to do here is validate the work done by SEM and handle subtypes.  */
 577
 578 tree
 579 build_binary_op (op_code, result_type, left_operand, right_operand)
 580      enum tree_code op_code;
 581      tree result_type;
 582      tree left_operand;
 583      tree right_operand;
 584 {
 585   tree left_type  = TREE_TYPE (left_operand);
 586   tree right_type = TREE_TYPE (right_operand);
 587   tree left_base_type = get_base_type (left_type);
 588   tree right_base_type = get_base_type (right_type);
 589   tree operation_type = result_type;
 590   tree best_type = 0;
 591   tree modulus;
 592   tree result;
 593   int has_side_effects = 0;
 594
 595   /* If one (but not both, unless they have the same object) operands are a
 596      WITH_RECORD_EXPR, do the operation and then surround it with the
 597      WITH_RECORD_EXPR.  Don't do this for assignment, for an ARRAY_REF, or
 598      for an ARRAY_RANGE_REF because we need to keep track of the
 599      WITH_RECORD_EXPRs on both operands very carefully.  */
 600   if (op_code != MODIFY_EXPR && op_code != ARRAY_REF
 601       && op_code != ARRAY_RANGE_REF
 602       && TREE_CODE (left_operand) == WITH_RECORD_EXPR
 603       && (TREE_CODE (right_operand) != WITH_RECORD_EXPR
 604           || operand_equal_p (TREE_OPERAND (left_operand, 1),
 605                               TREE_OPERAND (right_operand, 1), 0)))
 606     {
 607       tree right = right_operand;
 608
 609       if (TREE_CODE (right) == WITH_RECORD_EXPR)
 610         right = TREE_OPERAND (right, 0);
 611
 612       result = build_binary_op (op_code, result_type,
 613                                 TREE_OPERAND (left_operand, 0), right);
 614       return build (WITH_RECORD_EXPR, TREE_TYPE (result), result,
 615                     TREE_OPERAND (left_operand, 1));
 616     }
 617   else if (op_code != MODIFY_EXPR && op_code != ARRAY_REF
 618            && op_code != ARRAY_RANGE_REF
 619            && TREE_CODE (left_operand) != WITH_RECORD_EXPR
 620            && TREE_CODE (right_operand) == WITH_RECORD_EXPR)
 621     {
 622       result = build_binary_op (op_code, result_type, left_operand,
 623                                 TREE_OPERAND (right_operand, 0));
 624       return build (WITH_RECORD_EXPR, TREE_TYPE (result), result,
 625                     TREE_OPERAND (right_operand, 1));
 626     }
 627
 628   if (operation_type != 0
 629       && TREE_CODE (operation_type) == RECORD_TYPE
 630       && TYPE_LEFT_JUSTIFIED_MODULAR_P (operation_type))
 631     operation_type = TREE_TYPE (TYPE_FIELDS (operation_type));
 632
 633   if (operation_type != 0
 634       && ! AGGREGATE_TYPE_P (operation_type)
 635       && TYPE_EXTRA_SUBTYPE_P (operation_type))
 636     operation_type = get_base_type (operation_type);
 637
 638   modulus = (operation_type != 0 && TREE_CODE (operation_type) == INTEGER_TYPE
 639              && TYPE_MODULAR_P (operation_type)
 640              ? TYPE_MODULUS (operation_type) : 0);
 641
 642   switch (op_code)
 643     {
 644     case MODIFY_EXPR:
 645       /* If there were any integral or pointer conversions on LHS, remove
 646          them; we'll be putting them back below if needed.  Likewise for
 647          conversions between array and record types.  But don't do this if
 648          the right operand is not BLKmode (for packed arrays)
 649          unless we are not changing the mode.  */
 650       while ((TREE_CODE (left_operand) == CONVERT_EXPR
 651               || TREE_CODE (left_operand) == NOP_EXPR
 652               || TREE_CODE (left_operand) == VIEW_CONVERT_EXPR)
 653              && (((INTEGRAL_TYPE_P (left_type)
 654                    || POINTER_TYPE_P (left_type))
 655                   && (INTEGRAL_TYPE_P (TREE_TYPE
 656                                        (TREE_OPERAND (left_operand, 0)))
 657                       || POINTER_TYPE_P (TREE_TYPE
 658                                          (TREE_OPERAND (left_operand, 0)))))
 659                  || (((TREE_CODE (left_type) == RECORD_TYPE
 660                        /* Don't remove conversions to left-justified modular
 661                           types. */
 662                        && ! TYPE_LEFT_JUSTIFIED_MODULAR_P (left_type))
 663                       || TREE_CODE (left_type) == ARRAY_TYPE)
 664                      && ((TREE_CODE (TREE_TYPE
 665                                      (TREE_OPERAND (left_operand, 0)))
 666                           == RECORD_TYPE)
 667                          || (TREE_CODE (TREE_TYPE
 668                                         (TREE_OPERAND (left_operand, 0)))
 669                              == ARRAY_TYPE))
 670                      && (TYPE_MODE (right_type) == BLKmode
 671                          || (TYPE_MODE (left_type)
 672                              == TYPE_MODE (TREE_TYPE
 673                                            (TREE_OPERAND
 674                                             (left_operand, 0))))))))
 675         {
 676           left_operand = TREE_OPERAND (left_operand, 0);
 677           left_type = TREE_TYPE (left_operand);
 678         }
 679
 680       if (operation_type == 0)
 681         operation_type = left_type;
 682
 683       /* If the RHS has a conversion between record and array types and
 684          an inner type is no worse, use it.  Note we cannot do this for
 685          modular types or types with TYPE_ALIGN_OK, since the latter
 686          might indicate a conversion between a root type and a class-wide
 687          type, which we must not remove.  */
 688       while (TREE_CODE (right_operand) == VIEW_CONVERT_EXPR
 689              && ((TREE_CODE (right_type) == RECORD_TYPE
 690                   && ! TYPE_LEFT_JUSTIFIED_MODULAR_P (right_type)
 691                   && ! TYPE_ALIGN_OK (right_type)
 692                   && ! TYPE_IS_FAT_POINTER_P (right_type))
 693                  || TREE_CODE (right_type) == ARRAY_TYPE)
 694              && (((TREE_CODE (TREE_TYPE (TREE_OPERAND (right_operand, 0)))
 695                    == RECORD_TYPE)
 696                   && ! (TYPE_LEFT_JUSTIFIED_MODULAR_P
 697                         (TREE_TYPE (TREE_OPERAND (right_operand, 0))))
 698                   && ! (TYPE_ALIGN_OK
 699                         (TREE_TYPE (TREE_OPERAND (right_operand, 0))))
 700                   && ! (TYPE_IS_FAT_POINTER_P
 701                         (TREE_TYPE (TREE_OPERAND (right_operand, 0)))))
 702                  || (TREE_CODE (TREE_TYPE (TREE_OPERAND (right_operand, 0)))
 703                      == ARRAY_TYPE))
 704              && (0 == (best_type
 705                        == find_common_type (right_type,
 706                                             TREE_TYPE (TREE_OPERAND
 707                                                        (right_operand, 0))))
 708                  || right_type != best_type))
 709         {
 710           right_operand = TREE_OPERAND (right_operand, 0);
 711           right_type = TREE_TYPE (right_operand);
 712         }
 713
 714       /* If we are copying one array or record to another, find the best type
 715          to use.  */
 716       if (((TREE_CODE (left_type) == ARRAY_TYPE
 717             && TREE_CODE (right_type) == ARRAY_TYPE)
 718            || (TREE_CODE (left_type) == RECORD_TYPE
 719                && TREE_CODE (right_type) == RECORD_TYPE))
 720           && (best_type = find_common_type (left_type, right_type)) != 0)
 721         operation_type = best_type;
 722
 723       /* If a class-wide type may be involved, force use of the RHS type.  */
 724       if (TREE_CODE (right_type) == RECORD_TYPE && TYPE_ALIGN_OK (right_type))
 725         operation_type = right_type;
 726
 727       /* Ensure everything on the LHS is valid.  If we have a field reference,
 728          strip anything that get_inner_reference can handle.  Then remove any
 729          conversions with type types having the same code and mode.  Mark
 730          VIEW_CONVERT_EXPRs with TREE_ADDRESSABLE.  When done, we must have
 731          either an INDIRECT_REF or a decl.  */
 732       result = left_operand;
 733       while (1)
 734         {
 735           tree restype = TREE_TYPE (result);
 736
 737           if (TREE_CODE (result) == COMPONENT_REF
 738               || TREE_CODE (result) == ARRAY_REF
 739               || TREE_CODE (result) == ARRAY_RANGE_REF)
 740             while (handled_component_p (result))
 741               result = TREE_OPERAND (result, 0);
 742           else if (TREE_CODE (result) == REALPART_EXPR
 743                    || TREE_CODE (result) == IMAGPART_EXPR
 744                    || TREE_CODE (result) == WITH_RECORD_EXPR
 745                    || ((TREE_CODE (result) == NOP_EXPR
 746                         || TREE_CODE (result) == CONVERT_EXPR)
 747                        && (((TREE_CODE (restype)
 748                              == TREE_CODE (TREE_TYPE
 749                                            (TREE_OPERAND (result, 0))))
 750                              && (TYPE_MODE (TREE_TYPE
 751                                             (TREE_OPERAND (result, 0)))
 752                                  == TYPE_MODE (restype)))
 753                            || TYPE_ALIGN_OK (restype))))
 754             result = TREE_OPERAND (result, 0);
 755           else if (TREE_CODE (result) == VIEW_CONVERT_EXPR)
 756             {
 757               TREE_ADDRESSABLE (result) = 1;
 758               result = TREE_OPERAND (result, 0);
 759             }
 760           else
 761             break;
 762         }
 763
 764       if (TREE_CODE (result) != INDIRECT_REF && TREE_CODE (result) != NULL_EXPR
 765           && ! DECL_P (result))
 766         gigi_abort (516);
 767
 768       /* Convert the right operand to the operation type unless
 769          it is either already of the correct type or if the type
 770          involves a placeholder, since the RHS may not have the same
 771          record type.  */
 772       if (operation_type != right_type
 773           && (! (TREE_CODE (TYPE_SIZE (operation_type)) != INTEGER_CST
 774                  && contains_placeholder_p (TYPE_SIZE (operation_type)))))
 775         {
 776           /* For a variable-size type, with both BLKmode, convert using
 777              CONVERT_EXPR instead of an unchecked conversion since we don't
 778              need to make a temporary (and can't anyway).  */
 779           if (TREE_CODE (TYPE_SIZE (operation_type)) != INTEGER_CST
 780               && TYPE_MODE (TREE_TYPE (right_operand)) == BLKmode
 781               && TREE_CODE (right_operand) != UNCONSTRAINED_ARRAY_REF)
 782             right_operand = build1 (CONVERT_EXPR, operation_type,
 783                                     right_operand);
 784           else
 785             right_operand = convert (operation_type, right_operand);
 786
 787           right_type = operation_type;
 788         }
 789
 790       /* If the modes differ, make up a bogus type and convert the RHS to
 791          it.  This can happen with packed types.  */
 792       if (TYPE_MODE (left_type) != TYPE_MODE (right_type))
 793         {
 794           tree new_type = copy_node (left_type);
 795
 796           TYPE_SIZE (new_type) = TYPE_SIZE (right_type);
 797           TYPE_SIZE_UNIT (new_type) = TYPE_SIZE_UNIT (right_type);
 798           TYPE_MAIN_VARIANT (new_type) = new_type;
 799           right_operand = convert (new_type, right_operand);
 800         }
 801
 802       has_side_effects = 1;
 803       modulus = 0;
 804       break;
 805
 806     case ARRAY_REF:
 807       if (operation_type == 0)
 808         operation_type = TREE_TYPE (left_type);
 809
 810       /* ... fall through ... */
 811
 812     case ARRAY_RANGE_REF:
 813
 814       /* First convert the right operand to its base type.  This will
 815          prevent unneed signedness conversions when sizetype is wider than
 816          integer.  */
 817       right_operand = convert (right_base_type, right_operand);
 818       right_operand = convert (TYPE_DOMAIN (left_type), right_operand);
 819
 820       if (! TREE_CONSTANT (right_operand)
 821           || ! TREE_CONSTANT (TYPE_MIN_VALUE (right_type))
 822           || op_code == ARRAY_RANGE_REF)
 823         gnat_mark_addressable (left_operand);
 824
 825       modulus = 0;
 826       break;
 827
 828     case GE_EXPR:
 829     case LE_EXPR:
 830     case GT_EXPR:
 831     case LT_EXPR:
 832       if (POINTER_TYPE_P (left_type))
 833         gigi_abort (501);
 834
 835       /* ... fall through ... */
 836
 837     case EQ_EXPR:
 838     case NE_EXPR:
 839       /* If either operand is a NULL_EXPR, just return a new one.  */
 840       if (TREE_CODE (left_operand) == NULL_EXPR)
 841         return build (op_code, result_type,
 842                       build1 (NULL_EXPR, integer_type_node,
 843                               TREE_OPERAND (left_operand, 0)),
 844                       integer_zero_node);
 845
 846       else if (TREE_CODE (right_operand) == NULL_EXPR)
 847         return build (op_code, result_type,
 848                       build1 (NULL_EXPR, integer_type_node,
 849                               TREE_OPERAND (right_operand, 0)),
 850                       integer_zero_node);
 851
 852       /* If either object is a left-justified modular types, get the
 853          fields from within.  */
 854       if (TREE_CODE (left_type) == RECORD_TYPE
 855           && TYPE_LEFT_JUSTIFIED_MODULAR_P (left_type))
 856         {
 857           left_operand = convert (TREE_TYPE (TYPE_FIELDS (left_type)),
 858                                   left_operand);
 859           left_type = TREE_TYPE (left_operand);
 860           left_base_type = get_base_type (left_type);
 861         }
 862
 863       if (TREE_CODE (right_type) == RECORD_TYPE
 864           && TYPE_LEFT_JUSTIFIED_MODULAR_P (right_type))
 865         {
 866           right_operand = convert (TREE_TYPE (TYPE_FIELDS (right_type)),
 867                                   right_operand);
 868           right_type = TREE_TYPE (right_operand);
 869           right_base_type = get_base_type (right_type);
 870         }
 871
 872       /* If both objects are arrays, compare them specially.  */
 873       if ((TREE_CODE (left_type) == ARRAY_TYPE
 874            || (TREE_CODE (left_type) == INTEGER_TYPE
 875                && TYPE_HAS_ACTUAL_BOUNDS_P (left_type)))
 876           && (TREE_CODE (right_type) == ARRAY_TYPE
 877               || (TREE_CODE (right_type) == INTEGER_TYPE
 878                   && TYPE_HAS_ACTUAL_BOUNDS_P (right_type))))
 879         {
 880           result = compare_arrays (result_type, left_operand, right_operand);
 881
 882           if (op_code == EQ_EXPR)
 883             ;
 884           else if (op_code == NE_EXPR)
 885             result = invert_truthvalue (result);
 886           else
 887             gigi_abort (502);
 888
 889           return result;
 890         }
 891
 892       /* Otherwise, the base types must be the same unless the objects are
 893          records.  If we have records, use the best type and convert both
 894          operands to that type.  */
 895       if (left_base_type != right_base_type)
 896         {
 897           if (TREE_CODE (left_base_type) == RECORD_TYPE
 898               && TREE_CODE (right_base_type) == RECORD_TYPE)
 899             {
 900               /* The only way these are permitted to be the same is if both
 901                  types have the same name.  In that case, one of them must
 902                  not be self-referential.  Use that one as the best type.
 903                  Even better is if one is of fixed size.  */
 904               best_type = 0;
 905
 906               if (TYPE_NAME (left_base_type) == 0
 907                   || TYPE_NAME (left_base_type) != TYPE_NAME (right_base_type))
 908                 gigi_abort (503);
 909
 910               if (TREE_CONSTANT (TYPE_SIZE (left_base_type)))
 911                 best_type = left_base_type;
 912               else if (TREE_CONSTANT (TYPE_SIZE (right_base_type)))
 913                 best_type = right_base_type;
 914               else if (! contains_placeholder_p (TYPE_SIZE (left_base_type)))
 915                 best_type = left_base_type;
 916               else if (! contains_placeholder_p (TYPE_SIZE (right_base_type)))
 917                 best_type = right_base_type;
 918               else
 919                 gigi_abort (504);
 920
 921               left_operand = convert (best_type, left_operand);
 922               right_operand = convert (best_type, right_operand);
 923             }
 924           else
 925             gigi_abort (505);
 926         }
 927
 928       /* If we are comparing a fat pointer against zero, we need to
 929          just compare the data pointer.  */
 930       else if (TYPE_FAT_POINTER_P (left_base_type)
 931                && TREE_CODE (right_operand) == CONSTRUCTOR
 932                && integer_zerop (TREE_VALUE (TREE_OPERAND (right_operand, 1))))
 933         {
 934           right_operand = build_component_ref (left_operand, NULL_TREE,
 935                                                TYPE_FIELDS (left_base_type));
 936           left_operand = convert (TREE_TYPE (right_operand),
 937                                   integer_zero_node);
 938         }
 939       else
 940         {
 941           left_operand = convert (left_base_type, left_operand);
 942           right_operand = convert (right_base_type, right_operand);
 943         }
 944
 945       modulus = 0;
 946       break;
 947
 948     case PREINCREMENT_EXPR:
 949     case PREDECREMENT_EXPR:
 950     case POSTINCREMENT_EXPR:
 951     case POSTDECREMENT_EXPR:
 952       /* In these, the result type and the left operand type should be the
 953          same.  Do the operation in the base type of those and convert the
 954          right operand (which is an integer) to that type.
 955
 956          Note that these operations are only used in loop control where
 957          we guarantee that no overflow can occur.  So nothing special need
 958          be done for modular types.  */
 959
 960       if (left_type != result_type)
 961         gigi_abort (506);
 962
 963       operation_type = get_base_type (result_type);
 964       left_operand = convert (operation_type, left_operand);
 965       right_operand = convert (operation_type, right_operand);
 966       has_side_effects = 1;
 967       modulus = 0;
 968       break;
 969
 970     case LSHIFT_EXPR:
 971     case RSHIFT_EXPR:
 972     case LROTATE_EXPR:
 973     case RROTATE_EXPR:
 974        /* The RHS of a shift can be any type.  Also, ignore any modulus
 975          (we used to abort, but this is needed for unchecked conversion
 976          to modular types).  Otherwise, processing is the same as normal.  */
 977       if (operation_type != left_base_type)
 978         gigi_abort (514);
 979
 980       modulus = 0;
 981       left_operand = convert (operation_type, left_operand);
 982       break;
 983
 984     case TRUTH_ANDIF_EXPR:
 985     case TRUTH_ORIF_EXPR:
 986     case TRUTH_AND_EXPR:
 987     case TRUTH_OR_EXPR:
 988     case TRUTH_XOR_EXPR:
 989       left_operand = gnat_truthvalue_conversion (left_operand);
 990       right_operand = gnat_truthvalue_conversion (right_operand);
 991       goto common;
 992
 993     case BIT_AND_EXPR:
 994     case BIT_IOR_EXPR:
 995     case BIT_XOR_EXPR:
 996       /* For binary modulus, if the inputs are in range, so are the
 997          outputs.  */
 998       if (modulus != 0 && integer_pow2p (modulus))
 999         modulus = 0;
1000
1001       goto common;
1002
1003     case COMPLEX_EXPR:
1004       if (TREE_TYPE (result_type) != left_base_type
1005           || TREE_TYPE (result_type) != right_base_type)
1006         gigi_abort (515);
1007
1008       left_operand = convert (left_base_type, left_operand);
1009       right_operand = convert (right_base_type, right_operand);
1010       break;
1011
1012     case TRUNC_DIV_EXPR:   case TRUNC_MOD_EXPR:
1013     case CEIL_DIV_EXPR:    case CEIL_MOD_EXPR:
1014     case FLOOR_DIV_EXPR:   case FLOOR_MOD_EXPR:
1015     case ROUND_DIV_EXPR:   case ROUND_MOD_EXPR:
1016       /* These always produce results lower than either operand.  */
1017       modulus = 0;
1018       goto common;
1019
1020     default:
1021     common:
1022       /* The result type should be the same as the base types of the
1023          both operands (and they should be the same).  Convert
1024          everything to the result type.  */
1025
1026       if (operation_type != left_base_type
1027           || left_base_type != right_base_type)
1028         gigi_abort (507);
1029
1030       left_operand = convert (operation_type, left_operand);
1031       right_operand = convert (operation_type, right_operand);
1032     }
1033
1034   if (modulus != 0 && ! integer_pow2p (modulus))
1035     {
1036       result = nonbinary_modular_operation (op_code, operation_type,
1037                                             left_operand, right_operand);
1038       modulus = 0;
1039     }
1040   /* If either operand is a NULL_EXPR, just return a new one.  */
1041   else if (TREE_CODE (left_operand) == NULL_EXPR)
1042     return build1 (NULL_EXPR, operation_type, TREE_OPERAND (left_operand, 0));
1043   else if (TREE_CODE (right_operand) == NULL_EXPR)
1044     return build1 (NULL_EXPR, operation_type, TREE_OPERAND (right_operand, 0));
1045   else
1046     result = fold (build (op_code, operation_type,
1047                           left_operand, right_operand));
1048
1049   TREE_SIDE_EFFECTS (result) |= has_side_effects;
1050   TREE_CONSTANT (result)
1051     |= (TREE_CONSTANT (left_operand) & TREE_CONSTANT (right_operand)
1052         && op_code != ARRAY_REF && op_code != ARRAY_RANGE_REF);
1053
1054   if ((op_code == ARRAY_REF || op_code == ARRAY_RANGE_REF)
1055       && TYPE_VOLATILE (operation_type))
1056     TREE_THIS_VOLATILE (result) = 1;
1057
1058   /* If we are working with modular types, perform the MOD operation
1059      if something above hasn't eliminated the need for it.  */
1060   if (modulus != 0)
1061     result = fold (build (FLOOR_MOD_EXPR, operation_type, result,
1062                           convert (operation_type, modulus)));
1063
1064   if (result_type != 0 && result_type != operation_type)
1065     result = convert (result_type, result);
1066
1067   return result;
1068 }
1069 \f
1070 /* Similar, but for unary operations.  */
1071
1072 tree
1073 build_unary_op (op_code, result_type, operand)
1074      enum tree_code op_code;
1075      tree result_type;
1076      tree operand;
1077 {
1078   tree type = TREE_TYPE (operand);
1079   tree base_type = get_base_type (type);
1080   tree operation_type = result_type;
1081   tree result;
1082   int side_effects = 0;
1083
1084   /* If we have a WITH_RECORD_EXPR as our operand, do the operation first,
1085      then surround it with the WITH_RECORD_EXPR.  This allows GCC to do better
1086      expression folding.  */
1087   if (TREE_CODE (operand) == WITH_RECORD_EXPR)
1088     {
1089       result = build_unary_op (op_code, result_type,
1090                                TREE_OPERAND (operand, 0));
1091       return build (WITH_RECORD_EXPR, TREE_TYPE (result), result,
1092                     TREE_OPERAND (operand, 1));
1093     }
1094
1095   if (operation_type != 0
1096       && TREE_CODE (operation_type) == RECORD_TYPE
1097       && TYPE_LEFT_JUSTIFIED_MODULAR_P (operation_type))
1098     operation_type = TREE_TYPE (TYPE_FIELDS (operation_type));
1099
1100   if (operation_type != 0
1101       && ! AGGREGATE_TYPE_P (operation_type)
1102       && TYPE_EXTRA_SUBTYPE_P (operation_type))
1103     operation_type = get_base_type (operation_type);
1104
1105   switch (op_code)
1106     {
1107     case REALPART_EXPR:
1108     case IMAGPART_EXPR:
1109       if (operation_type == 0)
1110         result_type = operation_type = TREE_TYPE (type);
1111       else if (result_type != TREE_TYPE (type))
1112         gigi_abort (513);
1113
1114       result = fold (build1 (op_code, operation_type, operand));
1115       break;
1116
1117     case TRUTH_NOT_EXPR:
1118       if (result_type != base_type)
1119         gigi_abort (508);
1120
1121       result = invert_truthvalue (gnat_truthvalue_conversion (operand));
1122       break;
1123
1124     case ATTR_ADDR_EXPR:
1125     case ADDR_EXPR:
1126       switch (TREE_CODE (operand))
1127         {
1128         case INDIRECT_REF:
1129         case UNCONSTRAINED_ARRAY_REF:
1130           result = TREE_OPERAND (operand, 0);
1131
1132           /* Make sure the type here is a pointer, not a reference.
1133              GCC wants pointer types for function addresses.  */
1134           if (result_type == 0)
1135             result_type = build_pointer_type (type);
1136           break;
1137
1138         case NULL_EXPR:
1139           result = operand;
1140           TREE_TYPE (result) = type = build_pointer_type (type);
1141           break;
1142
1143         case ARRAY_REF:
1144         case ARRAY_RANGE_REF:
1145         case COMPONENT_REF:
1146         case BIT_FIELD_REF:
1147             /* If this is for 'Address, find the address of the prefix and
1148                add the offset to the field.  Otherwise, do this the normal
1149                way.  */
1150           if (op_code == ATTR_ADDR_EXPR)
1151             {
1152               HOST_WIDE_INT bitsize;
1153               HOST_WIDE_INT bitpos;
1154               tree offset, inner;
1155               enum machine_mode mode;
1156               int unsignedp, volatilep;
1157
1158               inner = get_inner_reference (operand, &bitsize, &bitpos, &offset,
1159                                            &mode, &unsignedp, &volatilep);
1160
1161               /* If INNER is a padding type whose field has a self-referential
1162                  size, convert to that inner type.  We know the offset is zero
1163                  and we need to have that type visible.  */
1164               if (TREE_CODE (TREE_TYPE (inner)) == RECORD_TYPE
1165                   && TYPE_IS_PADDING_P (TREE_TYPE (inner))
1166                   && (contains_placeholder_p
1167                       (TYPE_SIZE (TREE_TYPE (TYPE_FIELDS
1168                                              (TREE_TYPE (inner)))))))
1169                 inner = convert (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (inner))),
1170                                  inner);
1171
1172               /* Compute the offset as a byte offset from INNER.  */
1173               if (offset == 0)
1174                 offset = size_zero_node;
1175
1176               if (bitpos % BITS_PER_UNIT != 0)
1177                 post_error
1178                   ("taking address of object not aligned on storage unit?",
1179                    error_gnat_node);
1180
1181               offset = size_binop (PLUS_EXPR, offset,
1182                                    size_int (bitpos / BITS_PER_UNIT));
1183
1184               /* Take the address of INNER, convert the offset to void *, and
1185                  add then.  It will later be converted to the desired result
1186                  type, if any.  */
1187               inner = build_unary_op (ADDR_EXPR, NULL_TREE, inner);
1188               inner = convert (ptr_void_type_node, inner);
1189               offset = convert (ptr_void_type_node, offset);
1190               result = build_binary_op (PLUS_EXPR, ptr_void_type_node,
1191                                         inner, offset);
1192               result = convert (build_pointer_type (TREE_TYPE (operand)),
1193                                 result);
1194               break;
1195             }
1196           goto common;
1197
1198         case CONSTRUCTOR:
1199           /* If this is just a constructor for a padded record, we can
1200              just take the address of the single field and convert it to
1201              a pointer to our type.  */
1202           if (TREE_CODE (type) == RECORD_TYPE && TYPE_IS_PADDING_P (type))
1203             {
1204               result
1205                 = build_unary_op (ADDR_EXPR, NULL_TREE,
1206                                   TREE_VALUE (CONSTRUCTOR_ELTS (operand)));
1207               result = convert (build_pointer_type (TREE_TYPE (operand)),
1208                                 result);
1209               break;
1210             }
1211
1212           goto common;
1213
1214         case NOP_EXPR:
1215           if (AGGREGATE_TYPE_P (type)
1216               && AGGREGATE_TYPE_P (TREE_TYPE (TREE_OPERAND (operand, 0))))
1217             return build_unary_op (ADDR_EXPR, result_type,
1218                                    TREE_OPERAND (operand, 0));
1219
1220           /* If this NOP_EXPR doesn't change the mode, get the result type
1221              from this type and go down.  We need to do this in case
1222              this is a conversion of a CONST_DECL.  */
1223           if (TYPE_MODE (type) != BLKmode
1224               && (TYPE_MODE (type)
1225                   == TYPE_MODE (TREE_TYPE (TREE_OPERAND (operand, 0)))))
1226             return build_unary_op (ADDR_EXPR,
1227                                    (result_type == 0
1228                                     ? build_pointer_type (type)
1229                                     : result_type),
1230                                    TREE_OPERAND (operand, 0));
1231           goto common;
1232
1233         case CONST_DECL:
1234           operand = DECL_CONST_CORRESPONDING_VAR (operand);
1235
1236           /* ... fall through ... */
1237
1238         default:
1239         common:
1240
1241           if (type != error_mark_node)
1242             operation_type = build_pointer_type (type);
1243
1244           gnat_mark_addressable (operand);
1245           result = fold (build1 (ADDR_EXPR, operation_type, operand));
1246         }
1247
1248       TREE_CONSTANT (result) = staticp (operand) || TREE_CONSTANT (operand);
1249       break;
1250
1251     case INDIRECT_REF:
1252       /* If we want to refer to an entire unconstrained array,
1253          make up an expression to do so.  This will never survive to
1254          the backend.  If TYPE is a thin pointer, first convert the
1255          operand to a fat pointer.  */
1256       if (TYPE_THIN_POINTER_P (type)
1257           && TYPE_UNCONSTRAINED_ARRAY (TREE_TYPE (type)) != 0)
1258         {
1259           operand
1260             = convert (TREE_TYPE (TYPE_UNCONSTRAINED_ARRAY (TREE_TYPE (type))),
1261                        operand);
1262           type = TREE_TYPE (operand);
1263         }
1264
1265       if (TYPE_FAT_POINTER_P (type))
1266         result = build1 (UNCONSTRAINED_ARRAY_REF,
1267                          TYPE_UNCONSTRAINED_ARRAY (type), operand);
1268
1269       else if (TREE_CODE (operand) == ADDR_EXPR)
1270         result = TREE_OPERAND (operand, 0);
1271
1272       else
1273         {
1274           result = fold (build1 (op_code, TREE_TYPE (type), operand));
1275           TREE_READONLY (result) = TREE_READONLY (TREE_TYPE (type));
1276         }
1277
1278       side_effects = flag_volatile
1279         || (! TYPE_FAT_POINTER_P (type) && TYPE_VOLATILE (TREE_TYPE (type)));
1280       break;
1281
1282     case NEGATE_EXPR:
1283     case BIT_NOT_EXPR:
1284       {
1285         tree modulus = ((operation_type != 0
1286                          && TREE_CODE (operation_type) == INTEGER_TYPE
1287                          && TYPE_MODULAR_P (operation_type))
1288                         ? TYPE_MODULUS (operation_type) : 0);
1289         int mod_pow2 = modulus != 0 && integer_pow2p (modulus);
1290
1291         /* If this is a modular type, there are various possibilities
1292            depending on the operation and whether the modulus is a
1293            power of two or not.  */
1294
1295         if (modulus != 0)
1296           {
1297             if (operation_type != base_type)
1298               gigi_abort (509);
1299
1300             operand = convert (operation_type, operand);
1301
1302             /* The fastest in the negate case for binary modulus is
1303                the straightforward code; the TRUNC_MOD_EXPR below
1304                is an AND operation.  */
1305             if (op_code == NEGATE_EXPR && mod_pow2)
1306               result = fold (build (TRUNC_MOD_EXPR, operation_type,
1307                                     fold (build1 (NEGATE_EXPR, operation_type,
1308                                                   operand)),
1309                                     modulus));
1310
1311             /* For nonbinary negate case, return zero for zero operand,
1312                else return the modulus minus the operand.  If the modulus
1313                is a power of two minus one, we can do the subtraction
1314                as an XOR since it is equivalent and faster on most machines. */
1315             else if (op_code == NEGATE_EXPR && ! mod_pow2)
1316               {
1317                 if (integer_pow2p (fold (build (PLUS_EXPR, operation_type,
1318                                                 modulus,
1319                                                 convert (operation_type,
1320                                                          integer_one_node)))))
1321                   result = fold (build (BIT_XOR_EXPR, operation_type,
1322                                         operand, modulus));
1323                 else
1324                   result = fold (build (MINUS_EXPR, operation_type,
1325                                         modulus, operand));
1326
1327                 result = fold (build (COND_EXPR, operation_type,
1328                                       fold (build (NE_EXPR, integer_type_node,
1329                                                    operand,
1330                                                    convert (operation_type,
1331                                                             integer_zero_node))),
1332                                       result, operand));
1333               }
1334             else
1335               {
1336                 /* For the NOT cases, we need a constant equal to
1337                    the modulus minus one.  For a binary modulus, we
1338                    XOR against the constant and subtract the operand from
1339                    that constant for nonbinary modulus.  */
1340
1341                 tree cnst = fold (build (MINUS_EXPR, operation_type, modulus,
1342                                          convert (operation_type,
1343                                                   integer_one_node)));
1344
1345                 if (mod_pow2)
1346                   result = fold (build (BIT_XOR_EXPR, operation_type,
1347                                         operand, cnst));
1348                 else
1349                   result = fold (build (MINUS_EXPR, operation_type,
1350                                         cnst, operand));
1351               }
1352
1353             break;
1354           }
1355       }
1356
1357       /* ... fall through ... */
1358
1359     default:
1360       if (operation_type != base_type)
1361         gigi_abort (509);
1362
1363       result = fold (build1 (op_code, operation_type, convert (operation_type,
1364                                                                operand)));
1365     }
1366
1367   if (side_effects)
1368     {
1369       TREE_SIDE_EFFECTS (result) = 1;
1370       if (TREE_CODE (result) == INDIRECT_REF)
1371         TREE_THIS_VOLATILE (result) = TYPE_VOLATILE (TREE_TYPE (result));
1372     }
1373
1374   if (result_type != 0 && TREE_TYPE (result) != result_type)
1375     result = convert (result_type, result);
1376
1377   return result;
1378 }
1379 \f
1380 /* Similar, but for COND_EXPR.  */
1381
1382 tree
1383 build_cond_expr (result_type, condition_operand, true_operand, false_operand)
1384      tree result_type;
1385      tree condition_operand;
1386      tree true_operand;
1387      tree false_operand;
1388 {
1389   tree result;
1390   int addr_p = 0;
1391
1392   /* Front-end verifies that result, true and false operands have same base
1393      type. Convert everything to the result type.  */
1394
1395   true_operand  = convert (result_type, true_operand);
1396   false_operand = convert (result_type, false_operand);
1397
1398   /* If the result type is unconstrained, take the address of
1399      the operands and then dereference our result.  */
1400
1401   if (TREE_CODE (result_type) == UNCONSTRAINED_ARRAY_TYPE
1402       || (TREE_CODE (TYPE_SIZE (result_type)) != INTEGER_CST
1403           && contains_placeholder_p (TYPE_SIZE (result_type))))
1404     {
1405       addr_p = 1;
1406       result_type = build_pointer_type (result_type);
1407       true_operand = build_unary_op (ADDR_EXPR, result_type, true_operand);
1408       false_operand = build_unary_op (ADDR_EXPR, result_type, false_operand);
1409     }
1410
1411   result = fold (build (COND_EXPR, result_type, condition_operand,
1412                         true_operand, false_operand));
1413
1414   /* If either operand is a SAVE_EXPR (possibly surrounded by
1415      arithmetic, make sure it gets done.  */
1416   while (TREE_CODE_CLASS (TREE_CODE (true_operand)) == '1'
1417          || (TREE_CODE_CLASS (TREE_CODE (true_operand)) == '2'
1418             && TREE_CONSTANT (TREE_OPERAND (true_operand, 1))))
1419     true_operand = TREE_OPERAND (true_operand, 0);
1420
1421   while (TREE_CODE_CLASS (TREE_CODE (false_operand)) == '1'
1422          || (TREE_CODE_CLASS (TREE_CODE (false_operand)) == '2'
1423             && TREE_CONSTANT (TREE_OPERAND (false_operand, 1))))
1424     false_operand = TREE_OPERAND (false_operand, 0);
1425
1426   if (TREE_CODE (true_operand) == SAVE_EXPR)
1427     result = build (COMPOUND_EXPR, result_type, true_operand, result);
1428   if (TREE_CODE (false_operand) == SAVE_EXPR)
1429     result = build (COMPOUND_EXPR, result_type, false_operand, result);
1430
1431  if (addr_p)
1432     result = build_unary_op (INDIRECT_REF, NULL_TREE, result);
1433
1434   return result;
1435 }
1436 \f
1437
1438 /* Build a CALL_EXPR to call FUNDECL with one argument, ARG.  Return
1439    the CALL_EXPR.  */
1440
1441 tree
1442 build_call_1_expr (fundecl, arg)
1443      tree fundecl;
1444      tree arg;
1445 {
1446   tree call = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fundecl)),
1447                      build_unary_op (ADDR_EXPR, NULL_TREE, fundecl),
1448                      chainon (NULL_TREE, build_tree_list (NULL_TREE, arg)),
1449                      NULL_TREE);
1450
1451   TREE_SIDE_EFFECTS (call) = 1;
1452
1453   return call;
1454 }
1455
1456 /* Build a CALL_EXPR to call FUNDECL with two arguments, ARG1 & ARG2.  Return
1457    the CALL_EXPR.  */
1458
1459 tree
1460 build_call_2_expr (fundecl, arg1, arg2)
1461      tree fundecl;
1462      tree arg1, arg2;
1463 {
1464   tree call = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fundecl)),
1465                      build_unary_op (ADDR_EXPR, NULL_TREE, fundecl),
1466                      chainon (chainon (NULL_TREE,
1467                                        build_tree_list (NULL_TREE, arg1)),
1468                               build_tree_list (NULL_TREE, arg2)),
1469                      NULL_TREE);
1470
1471   TREE_SIDE_EFFECTS (call) = 1;
1472
1473   return call;
1474 }
1475
1476 /* Likewise to call FUNDECL with no arguments.  */
1477
1478 tree
1479 build_call_0_expr (fundecl)
1480      tree fundecl;
1481 {
1482   tree call = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fundecl)),
1483                      build_unary_op (ADDR_EXPR, NULL_TREE, fundecl),
1484                      NULL_TREE, NULL_TREE);
1485
1486   TREE_SIDE_EFFECTS (call) = 1;
1487
1488   return call;
1489 }
1490 \f
1491 /* Call a function that raises an exception and pass the line number and file
1492    name, if requested.  MSG says which exception function to call.  */
1493
1494 tree
1495 build_call_raise (msg)
1496      int msg;
1497 {
1498   tree fndecl = gnat_raise_decls[msg];
1499   const char *str = discard_file_names ? "" : ref_filename;
1500   int len = strlen (str) + 1;
1501   tree filename = build_string (len, str);
1502
1503   TREE_TYPE (filename)
1504     = build_array_type (char_type_node,
1505                         build_index_type (build_int_2 (len, 0)));
1506
1507   return
1508     build_call_2_expr (fndecl,
1509                        build1 (ADDR_EXPR, build_pointer_type (char_type_node),
1510                                filename),
1511                        build_int_2 (lineno, 0));
1512 }
1513 \f
1514 /* Return a CONSTRUCTOR of TYPE whose list is LIST.  */
1515
1516 tree
1517 build_constructor (type, list)
1518      tree type;
1519      tree list;
1520 {
1521   tree elmt;
1522   int allconstant = (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST);
1523   int side_effects = 0;
1524   tree result;
1525
1526   for (elmt = list; elmt; elmt = TREE_CHAIN (elmt))
1527     {
1528       if (! TREE_CONSTANT (TREE_VALUE (elmt))
1529           || (TREE_CODE (type) == RECORD_TYPE
1530               && DECL_BIT_FIELD (TREE_PURPOSE (elmt))
1531               && TREE_CODE (TREE_VALUE (elmt)) != INTEGER_CST))
1532         allconstant = 0;
1533
1534       if (TREE_SIDE_EFFECTS (TREE_VALUE (elmt)))
1535         side_effects = 1;
1536
1537       /* Propagate an NULL_EXPR from the size of the type.  We won't ever
1538          be executing the code we generate here in that case, but handle it
1539          specially to avoid the cmpiler blowing up.  */
1540       if (TREE_CODE (type) == RECORD_TYPE
1541           && (0 != (result
1542                     = contains_null_expr (DECL_SIZE (TREE_PURPOSE (elmt))))))
1543         return build1 (NULL_EXPR, type, TREE_OPERAND (result, 0));
1544     }
1545
1546   /* If TYPE is a RECORD_TYPE and the fields are not in the
1547      same order as their bit position, don't treat this as constant
1548      since varasm.c can't handle it.  */
1549   if (allconstant && TREE_CODE (type) == RECORD_TYPE)
1550     {
1551       tree last_pos = bitsize_zero_node;
1552       tree field;
1553
1554       for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
1555         {
1556           tree this_pos = bit_position (field);
1557
1558           if (TREE_CODE (this_pos) != INTEGER_CST
1559               || tree_int_cst_lt (this_pos, last_pos))
1560             {
1561               allconstant = 0;
1562               break;
1563             }
1564
1565           last_pos = this_pos;
1566         }
1567     }
1568
1569   result = build (CONSTRUCTOR, type, NULL_TREE, list);
1570   TREE_CONSTANT (result) = allconstant;
1571   TREE_STATIC (result) = allconstant;
1572   TREE_SIDE_EFFECTS (result) = side_effects;
1573   TREE_READONLY (result) = TREE_READONLY (type);
1574
1575   return result;
1576 }
1577 \f
1578 /* Return a COMPONENT_REF to access a field that is given by COMPONENT,
1579    an IDENTIFIER_NODE giving the name of the field, or FIELD, a FIELD_DECL,
1580    for the field.
1581
1582    We also handle the fact that we might have been passed a pointer to the
1583    actual record and know how to look for fields in variant parts.  */
1584
1585 static tree
1586 build_simple_component_ref (record_variable, component, field)
1587      tree record_variable;
1588      tree component;
1589      tree field;
1590 {
1591   tree record_type = TYPE_MAIN_VARIANT (TREE_TYPE (record_variable));
1592   tree ref;
1593
1594   if ((TREE_CODE (record_type) != RECORD_TYPE
1595        && TREE_CODE (record_type) != UNION_TYPE
1596        && TREE_CODE (record_type) != QUAL_UNION_TYPE)
1597       || TYPE_SIZE (record_type) == 0)
1598     gigi_abort (510);
1599
1600   /* Either COMPONENT or FIELD must be specified, but not both.  */
1601   if ((component != 0) == (field != 0))
1602     gigi_abort (511);
1603
1604   /* If no field was specified, look for a field with the specified name
1605      in the current record only.  */
1606   if (field == 0)
1607     for (field = TYPE_FIELDS (record_type); field;
1608          field = TREE_CHAIN (field))
1609       if (DECL_NAME (field) == component)
1610         break;
1611
1612   if (field == 0)
1613     return 0;
1614
1615   /* If this field is not in the specified record, see if we can find
1616      something in the record whose original field is the same as this one. */
1617   if (DECL_CONTEXT (field) != record_type)
1618     /* Check if there is a field with name COMPONENT in the record.  */
1619     {
1620       tree new_field;
1621
1622       /* First loop thru normal components.  */
1623
1624       for (new_field = TYPE_FIELDS (record_type); new_field != 0;
1625            new_field = TREE_CHAIN (new_field))
1626         if (DECL_ORIGINAL_FIELD (new_field) == field
1627             || new_field == DECL_ORIGINAL_FIELD (field)
1628             || (DECL_ORIGINAL_FIELD (field) != 0
1629                 && (DECL_ORIGINAL_FIELD (field)
1630                     == DECL_ORIGINAL_FIELD (new_field))))
1631           break;
1632
1633       /* Next, loop thru DECL_INTERNAL_P components if we haven't found
1634          the component in the first search. Doing this search in 2 steps
1635          is required to avoiding hidden homonymous fields in the
1636          _Parent field.  */
1637
1638       if (new_field == 0)
1639         for (new_field = TYPE_FIELDS (record_type); new_field != 0;
1640              new_field = TREE_CHAIN (new_field))
1641           if (DECL_INTERNAL_P (new_field))
1642             {
1643               tree field_ref
1644                 = build_simple_component_ref (record_variable,
1645                                               NULL_TREE, new_field);
1646               ref = build_simple_component_ref (field_ref, NULL_TREE, field);
1647
1648               if (ref != 0)
1649                 return ref;
1650             }
1651
1652       field = new_field;
1653     }
1654
1655   if (field == 0)
1656     return 0;
1657
1658   /* It would be nice to call "fold" here, but that can lose a type
1659      we need to tag a PLACEHOLDER_EXPR with, so we can't do it.  */
1660   ref = build (COMPONENT_REF, TREE_TYPE (field), record_variable, field);
1661
1662   if (TREE_READONLY (record_variable) || TREE_READONLY (field))
1663     TREE_READONLY (ref) = 1;
1664   if (TREE_THIS_VOLATILE (record_variable) || TREE_THIS_VOLATILE (field)
1665       || TYPE_VOLATILE (record_type))
1666     TREE_THIS_VOLATILE (ref) = 1;
1667
1668   return ref;
1669 }
1670 \f
1671 /* Like build_simple_component_ref, except that we give an error if the
1672    reference could not be found.  */
1673
1674 tree
1675 build_component_ref (record_variable, component, field)
1676      tree record_variable;
1677      tree component;
1678      tree field;
1679 {
1680   tree ref = build_simple_component_ref (record_variable, component, field);
1681
1682   if (ref != 0)
1683     return ref;
1684
1685   /* If FIELD was specified, assume this is an invalid user field so
1686      raise constraint error.  Otherwise, we can't find the type to return, so
1687      abort.  */
1688
1689   else if (field != 0)
1690     return build1 (NULL_EXPR, TREE_TYPE (field),
1691                    build_call_raise (CE_Discriminant_Check_Failed));
1692   else
1693     gigi_abort (512);
1694 }
1695 \f
1696 /* Build a GCC tree to call an allocation or deallocation function.
1697    If GNU_OBJ is nonzero, it is an object to deallocate.  Otherwise,
1698    generate an allocator.
1699
1700    GNU_SIZE is the size of the object in bytes and ALIGN is the alignment in
1701    bits.  GNAT_PROC, if present, is a procedure to call and GNAT_POOL is the
1702    storage pool to use.  If not preset, malloc and free will be used except
1703    if GNAT_PROC is the "fake" value of -1, in which case we allocate the
1704    object dynamically on the stack frame.  */
1705
1706 tree
1707 build_call_alloc_dealloc (gnu_obj, gnu_size, align, gnat_proc, gnat_pool)
1708      tree gnu_obj;
1709      tree gnu_size;
1710      int align;
1711      Entity_Id gnat_proc;
1712      Entity_Id gnat_pool;
1713 {
1714   tree gnu_align = size_int (align / BITS_PER_UNIT);
1715
1716   if (TREE_CODE (gnu_size) != INTEGER_CST && contains_placeholder_p (gnu_size))
1717     gnu_size = build (WITH_RECORD_EXPR, sizetype, gnu_size,
1718                       build_unary_op (INDIRECT_REF, NULL_TREE, gnu_obj));
1719
1720   if (Present (gnat_proc))
1721     {
1722       /* The storage pools are obviously always tagged types, but the
1723          secondary stack uses the same mechanism and is not tagged */
1724       if (Is_Tagged_Type (Etype (gnat_pool)))
1725         {
1726           /* The size is the third parameter; the alignment is the
1727              same type.  */
1728           Entity_Id gnat_size_type
1729             = Etype (Next_Formal (Next_Formal (First_Formal (gnat_proc))));
1730           tree gnu_size_type = gnat_to_gnu_type (gnat_size_type);
1731           tree gnu_proc = gnat_to_gnu (gnat_proc);
1732           tree gnu_proc_addr = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_proc);
1733           tree gnu_pool = gnat_to_gnu (gnat_pool);
1734           tree gnu_pool_addr = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_pool);
1735           tree gnu_args = NULL_TREE;
1736           tree gnu_call;
1737
1738           /* The first arg is always the address of the storage pool; next
1739              comes the address of the object, for a deallocator, then the
1740              size and alignment.  */
1741           gnu_args
1742             = chainon (gnu_args, build_tree_list (NULL_TREE, gnu_pool_addr));
1743
1744           if (gnu_obj)
1745             gnu_args
1746               = chainon (gnu_args, build_tree_list (NULL_TREE, gnu_obj));
1747
1748           gnu_args
1749             = chainon (gnu_args,
1750                        build_tree_list (NULL_TREE,
1751                                         convert (gnu_size_type, gnu_size)));
1752           gnu_args
1753             = chainon (gnu_args,
1754                        build_tree_list (NULL_TREE,
1755                                         convert (gnu_size_type, gnu_align)));
1756
1757           gnu_call = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (gnu_proc)),
1758                             gnu_proc_addr, gnu_args, NULL_TREE);
1759           TREE_SIDE_EFFECTS (gnu_call) = 1;
1760           return gnu_call;
1761         }
1762
1763       /* Secondary stack case.  */
1764       else
1765         {
1766           /* The size is the second parameter */
1767           Entity_Id gnat_size_type
1768             = Etype (Next_Formal (First_Formal (gnat_proc)));
1769           tree gnu_size_type = gnat_to_gnu_type (gnat_size_type);
1770           tree gnu_proc = gnat_to_gnu (gnat_proc);
1771           tree gnu_proc_addr = build_unary_op (ADDR_EXPR, NULL_TREE, gnu_proc);
1772           tree gnu_args = NULL_TREE;
1773           tree gnu_call;
1774
1775           /* The first arg is the address of the object, for a
1776              deallocator, then the size */
1777           if (gnu_obj)
1778             gnu_args
1779               = chainon (gnu_args, build_tree_list (NULL_TREE, gnu_obj));
1780
1781           gnu_args
1782             = chainon (gnu_args,
1783                        build_tree_list (NULL_TREE,
1784                                         convert (gnu_size_type, gnu_size)));
1785
1786           gnu_call = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (gnu_proc)),
1787                             gnu_proc_addr, gnu_args, NULL_TREE);
1788           TREE_SIDE_EFFECTS (gnu_call) = 1;
1789           return gnu_call;
1790         }
1791     }
1792
1793   else if (gnu_obj)
1794     return build_call_1_expr (free_decl, gnu_obj);
1795   else if (gnat_pool == -1)
1796     {
1797       /* If the size is a constant, we can put it in the fixed portion of
1798          the stack frame to avoid the need to adjust the stack pointer.  */
1799       if (TREE_CODE (gnu_size) == INTEGER_CST && ! flag_stack_check)
1800         {
1801           tree gnu_range
1802             = build_range_type (NULL_TREE, size_one_node, gnu_size);
1803           tree gnu_array_type = build_array_type (char_type_node, gnu_range);
1804           tree gnu_decl =
1805             create_var_decl (get_identifier ("RETVAL"), NULL_TREE,
1806                              gnu_array_type, NULL_TREE, 0, 0, 0, 0, 0);
1807
1808           return convert (ptr_void_type_node,
1809                           build_unary_op (ADDR_EXPR, NULL_TREE, gnu_decl));
1810         }
1811       else
1812         return build (ALLOCATE_EXPR, ptr_void_type_node, gnu_size, gnu_align);
1813     }
1814   else
1815     return build_call_1_expr (malloc_decl, gnu_size);
1816 }
1817 \f
1818 /* Build a GCC tree to correspond to allocating an object of TYPE whose
1819    initial value is INIT, if INIT is nonzero.  Convert the expression to
1820    RESULT_TYPE, which must be some type of pointer.  Return the tree.
1821    GNAT_PROC and GNAT_POOL optionally give the procedure to call and
1822    the storage pool to use.  */
1823
1824 tree
1825 build_allocator (type, init, result_type, gnat_proc, gnat_pool)
1826      tree type;
1827      tree init;
1828      tree result_type;
1829      Entity_Id gnat_proc;
1830      Entity_Id gnat_pool;
1831 {
1832   tree size = TYPE_SIZE_UNIT (type);
1833   tree result;
1834
1835   /* If the initializer, if present, is a NULL_EXPR, just return a new one.  */
1836   if (init != 0 && TREE_CODE (init) == NULL_EXPR)
1837     return build1 (NULL_EXPR, result_type, TREE_OPERAND (init, 0));
1838
1839   /* If RESULT_TYPE is a fat or thin pointer, set SIZE to be the sum of the
1840      sizes of the object and its template.  Allocate the whole thing and
1841      fill in the parts that are known.  */
1842   else if (TYPE_FAT_OR_THIN_POINTER_P (result_type))
1843     {
1844       tree template_type
1845         = (TYPE_FAT_POINTER_P (result_type)
1846            ? TREE_TYPE (TREE_TYPE (TREE_CHAIN (TYPE_FIELDS (result_type))))
1847            : TREE_TYPE (TYPE_FIELDS (TREE_TYPE (result_type))));
1848       tree storage_type
1849         = build_unc_object_type (template_type, type,
1850                                  get_identifier ("ALLOC"));
1851       tree storage_ptr_type = build_pointer_type (storage_type);
1852       tree storage;
1853       tree template_cons = NULL_TREE;
1854
1855       size = TYPE_SIZE_UNIT (storage_type);
1856
1857       if (TREE_CODE (size) != INTEGER_CST
1858           && contains_placeholder_p (size))
1859         size = build (WITH_RECORD_EXPR, sizetype, size, init);
1860
1861       /* If the size overflows, pass -1 so the allocator will raise
1862          storage error.  */
1863       if (TREE_CODE (size) == INTEGER_CST && TREE_OVERFLOW (size))
1864         size = ssize_int (-1);
1865
1866       storage = build_call_alloc_dealloc (NULL_TREE, size,
1867                                           TYPE_ALIGN (storage_type),
1868                                           gnat_proc, gnat_pool);
1869       storage = convert (storage_ptr_type, protect_multiple_eval (storage));
1870
1871       if (TREE_CODE (type) == RECORD_TYPE && TYPE_IS_PADDING_P (type))
1872         {
1873           type = TREE_TYPE (TYPE_FIELDS (type));
1874
1875           if (init != 0)
1876             init = convert (type, init);
1877         }
1878
1879       /* If there is an initializing expression, make a constructor for
1880          the entire object including the bounds and copy it into the
1881          object.  If there is no initializing expression, just set the
1882          bounds.  */
1883       if (init != 0)
1884         {
1885           template_cons = tree_cons (TREE_CHAIN (TYPE_FIELDS (storage_type)),
1886                                      init, NULL_TREE);
1887           template_cons = tree_cons (TYPE_FIELDS (storage_type),
1888                                      build_template (template_type, type,
1889                                                      init),
1890                                      template_cons);
1891
1892           return convert
1893             (result_type,
1894              build (COMPOUND_EXPR, storage_ptr_type,
1895                     build_binary_op
1896                     (MODIFY_EXPR, storage_type,
1897                      build_unary_op (INDIRECT_REF, NULL_TREE,
1898                                      convert (storage_ptr_type, storage)),
1899                      build_constructor (storage_type, template_cons)),
1900                     convert (storage_ptr_type, storage)));
1901         }
1902       else
1903         return build
1904           (COMPOUND_EXPR, result_type,
1905            build_binary_op
1906            (MODIFY_EXPR, template_type,
1907             build_component_ref
1908             (build_unary_op (INDIRECT_REF, NULL_TREE,
1909                              convert (storage_ptr_type, storage)),
1910              NULL_TREE, TYPE_FIELDS (storage_type)),
1911             build_template (template_type, type, NULL_TREE)),
1912            convert (result_type, convert (storage_ptr_type, storage)));
1913     }
1914
1915   /* If we have an initializing expression, see if its size is simpler
1916      than the size from the type.  */
1917   if (init != 0 && TYPE_SIZE_UNIT (TREE_TYPE (init)) != 0
1918       && (TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (init))) == INTEGER_CST
1919           || (TREE_CODE (size) != INTEGER_CST
1920               && contains_placeholder_p (size))))
1921     size = TYPE_SIZE_UNIT (TREE_TYPE (init));
1922
1923   /* If the size is still self-referential, reference the initializing
1924      expression, if it is present.  If not, this must have been a
1925      call to allocate a library-level object, in which case we use
1926      the maximum size.  */
1927   if (TREE_CODE (size) != INTEGER_CST && contains_placeholder_p (size))
1928     {
1929       if (init == 0)
1930         size = max_size (size, 1);
1931       else
1932         size = build (WITH_RECORD_EXPR, sizetype, size, init);
1933     }
1934
1935   /* If the size overflows, pass -1 so the allocator will raise
1936      storage error.  */
1937   if (TREE_CODE (size) == INTEGER_CST && TREE_OVERFLOW (size))
1938     size = ssize_int (-1);
1939
1940   /* If this is a type whose alignment is larger than the
1941      biggest we support in normal alignment and this is in
1942      the default storage pool, make an "aligning type", allocate
1943      it, point to the field we need, and return that.  */
1944   if (TYPE_ALIGN (type) > BIGGEST_ALIGNMENT
1945       && No (gnat_proc))
1946     {
1947       tree new_type = make_aligning_type (type, TYPE_ALIGN (type), size);
1948
1949       result = build_call_alloc_dealloc (NULL_TREE, TYPE_SIZE (new_type),
1950                                          BIGGEST_ALIGNMENT, Empty, Empty);
1951       result = save_expr (result);
1952       result = convert (build_pointer_type (new_type), result);
1953       result = build_unary_op (INDIRECT_REF, NULL_TREE, result);
1954       result = build_component_ref (result, NULL_TREE,
1955                                     TYPE_FIELDS (new_type));
1956       result = convert (result_type,
1957                         build_unary_op (ADDR_EXPR, NULL_TREE, result));
1958     }
1959   else
1960     result = convert (result_type,
1961                       build_call_alloc_dealloc (NULL_TREE, size,
1962                                                 TYPE_ALIGN (type),
1963                                                 gnat_proc, gnat_pool));
1964
1965   /* If we have an initial value, put the new address into a SAVE_EXPR, assign
1966      the value, and return the address.  Do this with a COMPOUND_EXPR.  */
1967
1968   if (init)
1969     {
1970       result = save_expr (result);
1971       result
1972         = build (COMPOUND_EXPR, TREE_TYPE (result),
1973                  build_binary_op
1974                  (MODIFY_EXPR, TREE_TYPE (TREE_TYPE (result)),
1975                   build_unary_op (INDIRECT_REF, TREE_TYPE (TREE_TYPE (result)),
1976                                   result),
1977                   init),
1978                  result);
1979     }
1980
1981   return convert (result_type, result);
1982 }
1983 \f
1984 /* Fill in a VMS descriptor for EXPR and return a constructor for it.
1985    GNAT_FORMAL is how we find the descriptor record.  */
1986
1987 tree
1988 fill_vms_descriptor (expr, gnat_formal)
1989      tree expr;
1990      Entity_Id gnat_formal;
1991 {
1992   tree record_type = TREE_TYPE (TREE_TYPE (get_gnu_tree (gnat_formal)));
1993   tree field;
1994   tree const_list = 0;
1995
1996   expr = maybe_unconstrained_array (expr);
1997   gnat_mark_addressable (expr);
1998
1999   for (field = TYPE_FIELDS (record_type); field; field = TREE_CHAIN (field))
2000     {
2001       tree init = DECL_INITIAL (field);
2002
2003       if (TREE_CODE (init) != INTEGER_CST
2004           && contains_placeholder_p (init))
2005         init = build (WITH_RECORD_EXPR, TREE_TYPE (init), init, expr);
2006
2007       const_list = tree_cons (field, convert (TREE_TYPE (field), init),
2008                               const_list);
2009     }
2010
2011   return build_constructor (record_type, nreverse (const_list));
2012 }
2013
2014 /* Indicate that we need to make the address of EXPR_NODE and it therefore
2015    should not be allocated in a register.  Returns true if successful.  */
2016
2017 bool
2018 gnat_mark_addressable (expr_node)
2019      tree expr_node;
2020 {
2021   while (1)
2022     switch (TREE_CODE (expr_node))
2023       {
2024       case ADDR_EXPR:
2025       case COMPONENT_REF:
2026       case ARRAY_REF:
2027       case ARRAY_RANGE_REF:
2028       case REALPART_EXPR:
2029       case IMAGPART_EXPR:
2030       case NOP_EXPR:
2031         expr_node = TREE_OPERAND (expr_node, 0);
2032         break;
2033
2034       case CONSTRUCTOR:
2035         TREE_ADDRESSABLE (expr_node) = 1;
2036         return true;
2037
2038       case VAR_DECL:
2039       case PARM_DECL:
2040       case RESULT_DECL:
2041         put_var_into_stack (expr_node);
2042         TREE_ADDRESSABLE (expr_node) = 1;
2043         return true;
2044
2045       case FUNCTION_DECL:
2046         TREE_ADDRESSABLE (expr_node) = 1;
2047         return true;
2048
2049       case CONST_DECL:
2050         return (DECL_CONST_CORRESPONDING_VAR (expr_node) != 0
2051                 && (gnat_mark_addressable
2052                     (DECL_CONST_CORRESPONDING_VAR (expr_node))));
2053       default:
2054         return true;
2055     }
2056 }