gcc/convert.c

   1 /* Utility routines for data type conversion for GCC.
   2    Copyright (C) 1987, 1988, 1991, 1992, 1993, 1994, 1995, 1997, 1998,
   3    2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22
  23 /* These routines are somewhat language-independent utility function
  24    intended to be called by the language-specific convert () functions.  */
  25
  26 #include "config.h"
  27 #include "system.h"
  28 #include "coretypes.h"
  29 #include "tm.h"
  30 #include "tree.h"
  31 #include "flags.h"
  32 #include "convert.h"
  33 #include "toplev.h"
  34 #include "langhooks.h"
  35 #include "real.h"
  36 /* Convert EXPR to some pointer or reference type TYPE.
  37
  38    EXPR must be pointer, reference, integer, enumeral, or literal zero;
  39    in other cases error is called.  */
  40
  41 tree
  42 convert_to_pointer (tree type, tree expr)
  43 {
  44   if (integer_zerop (expr))
  45     {
  46       expr = build_int_cst (type, 0);
  47       return expr;
  48     }
  49
  50   switch (TREE_CODE (TREE_TYPE (expr)))
  51     {
  52     case POINTER_TYPE:
  53     case REFERENCE_TYPE:
  54       return build1 (NOP_EXPR, type, expr);
  55
  56     case INTEGER_TYPE:
  57     case ENUMERAL_TYPE:
  58     case BOOLEAN_TYPE:
  59     case CHAR_TYPE:
  60       if (TYPE_PRECISION (TREE_TYPE (expr)) == POINTER_SIZE)
  61         return build1 (CONVERT_EXPR, type, expr);
  62
  63       return
  64         convert_to_pointer (type,
  65                             convert (lang_hooks.types.type_for_size
  66                                      (POINTER_SIZE, 0), expr));
  67
  68     default:
  69       error ("cannot convert to a pointer type");
  70       return convert_to_pointer (type, integer_zero_node);
  71     }
  72 }
  73
  74 /* Avoid any floating point extensions from EXP.  */
  75 tree
  76 strip_float_extensions (tree exp)
  77 {
  78   tree sub, expt, subt;
  79
  80   /*  For floating point constant look up the narrowest type that can hold
  81       it properly and handle it like (type)(narrowest_type)constant.
  82       This way we can optimize for instance a=a*2.0 where "a" is float
  83       but 2.0 is double constant.  */
  84   if (TREE_CODE (exp) == REAL_CST)
  85     {
  86       REAL_VALUE_TYPE orig;
  87       tree type = NULL;
  88
  89       orig = TREE_REAL_CST (exp);
  90       if (TYPE_PRECISION (TREE_TYPE (exp)) > TYPE_PRECISION (float_type_node)
  91           && exact_real_truncate (TYPE_MODE (float_type_node), &orig))
  92         type = float_type_node;
  93       else if (TYPE_PRECISION (TREE_TYPE (exp))
  94                > TYPE_PRECISION (double_type_node)
  95                && exact_real_truncate (TYPE_MODE (double_type_node), &orig))
  96         type = double_type_node;
  97       if (type)
  98         return build_real (type, real_value_truncate (TYPE_MODE (type), orig));
  99     }
 100
 101   if (TREE_CODE (exp) != NOP_EXPR
 102       && TREE_CODE (exp) != CONVERT_EXPR)
 103     return exp;
 104
 105   sub = TREE_OPERAND (exp, 0);
 106   subt = TREE_TYPE (sub);
 107   expt = TREE_TYPE (exp);
 108
 109   if (!FLOAT_TYPE_P (subt))
 110     return exp;
 111
 112   if (TYPE_PRECISION (subt) > TYPE_PRECISION (expt))
 113     return exp;
 114
 115   return strip_float_extensions (sub);
 116 }
 117
 118
 119 /* Convert EXPR to some floating-point type TYPE.
 120
 121    EXPR must be float, integer, or enumeral;
 122    in other cases error is called.  */
 123
 124 tree
 125 convert_to_real (tree type, tree expr)
 126 {
 127   enum built_in_function fcode = builtin_mathfn_code (expr);
 128   tree itype = TREE_TYPE (expr);
 129
 130   /* Disable until we figure out how to decide whether the functions are
 131      present in runtime.  */
 132   /* Convert (float)sqrt((double)x) where x is float into sqrtf(x) */
 133   if (optimize
 134       && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 135           || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 136     {
 137       switch (fcode)
 138         {
 139 #define CASE_MATHFN(FN) case BUILT_IN_##FN: case BUILT_IN_##FN##L:
 140           CASE_MATHFN (ACOS)
 141           CASE_MATHFN (ACOSH)
 142           CASE_MATHFN (ASIN)
 143           CASE_MATHFN (ASINH)
 144           CASE_MATHFN (ATAN)
 145           CASE_MATHFN (ATANH)
 146           CASE_MATHFN (CBRT)
 147           CASE_MATHFN (COS)
 148           CASE_MATHFN (COSH)
 149           CASE_MATHFN (ERF)
 150           CASE_MATHFN (ERFC)
 151           CASE_MATHFN (EXP)
 152           CASE_MATHFN (EXP10)
 153           CASE_MATHFN (EXP2)
 154           CASE_MATHFN (EXPM1)
 155           CASE_MATHFN (FABS)
 156           CASE_MATHFN (GAMMA)
 157           CASE_MATHFN (J0)
 158           CASE_MATHFN (J1)
 159           CASE_MATHFN (LGAMMA)
 160           CASE_MATHFN (LOG)
 161           CASE_MATHFN (LOG10)
 162           CASE_MATHFN (LOG1P)
 163           CASE_MATHFN (LOG2)
 164           CASE_MATHFN (LOGB)
 165           CASE_MATHFN (POW10)
 166           CASE_MATHFN (SIN)
 167           CASE_MATHFN (SINH)
 168           CASE_MATHFN (SQRT)
 169           CASE_MATHFN (TAN)
 170           CASE_MATHFN (TANH)
 171           CASE_MATHFN (TGAMMA)
 172           CASE_MATHFN (Y0)
 173           CASE_MATHFN (Y1)
 174 #undef CASE_MATHFN
 175             {
 176               tree arg0 = strip_float_extensions (TREE_VALUE (TREE_OPERAND (expr, 1)));
 177               tree newtype = type;
 178
 179               /* We have (outertype)sqrt((innertype)x).  Choose the wider mode from
 180                  the both as the safe type for operation.  */
 181               if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (type))
 182                 newtype = TREE_TYPE (arg0);
 183
 184               /* Be careful about integer to fp conversions.
 185                  These may overflow still.  */
 186               if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 187                   && TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 188                   && (TYPE_MODE (newtype) == TYPE_MODE (double_type_node)
 189                       || TYPE_MODE (newtype) == TYPE_MODE (float_type_node)))
 190                 {
 191                   tree arglist;
 192                   tree fn = mathfn_built_in (newtype, fcode);
 193
 194                   if (fn)
 195                   {
 196                     arglist = build_tree_list (NULL_TREE, fold (convert_to_real (newtype, arg0)));
 197                     expr = build_function_call_expr (fn, arglist);
 198                     if (newtype == type)
 199                       return expr;
 200                   }
 201                 }
 202             }
 203         default:
 204           break;
 205         }
 206     }
 207   if (optimize
 208       && (((fcode == BUILT_IN_FLOORL
 209            || fcode == BUILT_IN_CEILL
 210            || fcode == BUILT_IN_ROUNDL
 211            || fcode == BUILT_IN_RINTL
 212            || fcode == BUILT_IN_TRUNCL
 213            || fcode == BUILT_IN_NEARBYINTL)
 214           && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 215               || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 216           || ((fcode == BUILT_IN_FLOOR
 217                || fcode == BUILT_IN_CEIL
 218                || fcode == BUILT_IN_ROUND
 219                || fcode == BUILT_IN_RINT
 220                || fcode == BUILT_IN_TRUNC
 221                || fcode == BUILT_IN_NEARBYINT)
 222               && (TYPE_MODE (type) == TYPE_MODE (float_type_node)))))
 223     {
 224       tree fn = mathfn_built_in (type, fcode);
 225
 226       if (fn)
 227         {
 228           tree arg0 = strip_float_extensions (TREE_VALUE (TREE_OPERAND (expr,
 229                                                                         1)));
 230           tree arglist = build_tree_list (NULL_TREE,
 231                                           fold (convert_to_real (type, arg0)));
 232
 233           return build_function_call_expr (fn, arglist);
 234         }
 235     }
 236
 237   /* Propagate the cast into the operation.  */
 238   if (itype != type && FLOAT_TYPE_P (type))
 239     switch (TREE_CODE (expr))
 240       {
 241         /* Convert (float)-x into -(float)x.  This is always safe.  */
 242         case ABS_EXPR:
 243         case NEGATE_EXPR:
 244           if (TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (expr)))
 245             return build1 (TREE_CODE (expr), type,
 246                            fold (convert_to_real (type,
 247                                                   TREE_OPERAND (expr, 0))));
 248           break;
 249         /* Convert (outertype)((innertype0)a+(innertype1)b)
 250            into ((newtype)a+(newtype)b) where newtype
 251            is the widest mode from all of these.  */
 252         case PLUS_EXPR:
 253         case MINUS_EXPR:
 254         case MULT_EXPR:
 255         case RDIV_EXPR:
 256            {
 257              tree arg0 = strip_float_extensions (TREE_OPERAND (expr, 0));
 258              tree arg1 = strip_float_extensions (TREE_OPERAND (expr, 1));
 259
 260              if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 261                  && FLOAT_TYPE_P (TREE_TYPE (arg1)))
 262                {
 263                   tree newtype = type;
 264                   if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (newtype))
 265                     newtype = TREE_TYPE (arg0);
 266                   if (TYPE_PRECISION (TREE_TYPE (arg1)) > TYPE_PRECISION (newtype))
 267                     newtype = TREE_TYPE (arg1);
 268                   if (TYPE_PRECISION (newtype) < TYPE_PRECISION (itype))
 269                     {
 270                       expr = build2 (TREE_CODE (expr), newtype,
 271                                      fold (convert_to_real (newtype, arg0)),
 272                                      fold (convert_to_real (newtype, arg1)));
 273                       if (newtype == type)
 274                         return expr;
 275                     }
 276                }
 277            }
 278           break;
 279         default:
 280           break;
 281       }
 282
 283   switch (TREE_CODE (TREE_TYPE (expr)))
 284     {
 285     case REAL_TYPE:
 286       return build1 (flag_float_store ? CONVERT_EXPR : NOP_EXPR,
 287                      type, expr);
 288
 289     case INTEGER_TYPE:
 290     case ENUMERAL_TYPE:
 291     case BOOLEAN_TYPE:
 292     case CHAR_TYPE:
 293       return build1 (FLOAT_EXPR, type, expr);
 294
 295     case COMPLEX_TYPE:
 296       return convert (type,
 297                       fold (build1 (REALPART_EXPR,
 298                                     TREE_TYPE (TREE_TYPE (expr)), expr)));
 299
 300     case POINTER_TYPE:
 301     case REFERENCE_TYPE:
 302       error ("pointer value used where a floating point value was expected");
 303       return convert_to_real (type, integer_zero_node);
 304
 305     default:
 306       error ("aggregate value used where a float was expected");
 307       return convert_to_real (type, integer_zero_node);
 308     }
 309 }
 310
 311 /* Convert EXPR to some integer (or enum) type TYPE.
 312
 313    EXPR must be pointer, integer, discrete (enum, char, or bool), float, or
 314    vector; in other cases error is called.
 315
 316    The result of this is always supposed to be a newly created tree node
 317    not in use in any existing structure.  */
 318
 319 tree
 320 convert_to_integer (tree type, tree expr)
 321 {
 322   enum tree_code ex_form = TREE_CODE (expr);
 323   tree intype = TREE_TYPE (expr);
 324   unsigned int inprec = TYPE_PRECISION (intype);
 325   unsigned int outprec = TYPE_PRECISION (type);
 326
 327   /* An INTEGER_TYPE cannot be incomplete, but an ENUMERAL_TYPE can
 328      be.  Consider `enum E = { a, b = (enum E) 3 };'.  */
 329   if (!COMPLETE_TYPE_P (type))
 330     {
 331       error ("conversion to incomplete type");
 332       return error_mark_node;
 333     }
 334
 335   /* Convert e.g. (long)round(d) -> lround(d).  */
 336   /* If we're converting to char, we may encounter differing behavior
 337      between converting from double->char vs double->long->char.
 338      We're in "undefined" territory but we prefer to be conservative,
 339      so only proceed in "unsafe" math mode.  */
 340   if (optimize
 341       && (flag_unsafe_math_optimizations
 342           || (long_integer_type_node
 343               && outprec >= TYPE_PRECISION (long_integer_type_node))))
 344     {
 345       tree s_expr = strip_float_extensions (expr);
 346       tree s_intype = TREE_TYPE (s_expr);
 347       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 348       tree fn = 0;
 349
 350       switch (fcode)
 351         {
 352         case BUILT_IN_ROUND: case BUILT_IN_ROUNDF: case BUILT_IN_ROUNDL:
 353           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 354             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 355           else
 356             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 357           break;
 358
 359         case BUILT_IN_RINT: case BUILT_IN_RINTF: case BUILT_IN_RINTL:
 360           /* Only convert rint* if we can ignore math exceptions.  */
 361           if (flag_trapping_math)
 362             break;
 363           /* ... Fall through ...  */
 364         case BUILT_IN_NEARBYINT: case BUILT_IN_NEARBYINTF: case BUILT_IN_NEARBYINTL:
 365           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 366             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 367           else
 368             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 369           break;
 370         default:
 371           break;
 372         }
 373
 374       if (fn)
 375         {
 376           tree arglist = TREE_OPERAND (s_expr, 1);
 377           tree newexpr = build_function_call_expr (fn, arglist);
 378           return convert_to_integer (type, newexpr);
 379         }
 380     }
 381
 382   switch (TREE_CODE (intype))
 383     {
 384     case POINTER_TYPE:
 385     case REFERENCE_TYPE:
 386       if (integer_zerop (expr))
 387         expr = integer_zero_node;
 388       else
 389         expr = fold (build1 (CONVERT_EXPR,
 390                              lang_hooks.types.type_for_size (POINTER_SIZE, 0),
 391                              expr));
 392
 393       return convert_to_integer (type, expr);
 394
 395     case INTEGER_TYPE:
 396     case ENUMERAL_TYPE:
 397     case BOOLEAN_TYPE:
 398     case CHAR_TYPE:
 399       /* If this is a logical operation, which just returns 0 or 1, we can
 400          change the type of the expression.  */
 401
 402       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 403         {
 404           expr = copy_node (expr);
 405           TREE_TYPE (expr) = type;
 406           return expr;
 407         }
 408
 409       /* If we are widening the type, put in an explicit conversion.
 410          Similarly if we are not changing the width.  After this, we know
 411          we are truncating EXPR.  */
 412
 413       else if (outprec >= inprec)
 414         {
 415           enum tree_code code;
 416
 417           /* If the precision of the EXPR's type is K bits and the
 418              destination mode has more bits, and the sign is changing,
 419              it is not safe to use a NOP_EXPR.  For example, suppose
 420              that EXPR's type is a 3-bit unsigned integer type, the
 421              TYPE is a 3-bit signed integer type, and the machine mode
 422              for the types is 8-bit QImode.  In that case, the
 423              conversion necessitates an explicit sign-extension.  In
 424              the signed-to-unsigned case the high-order bits have to
 425              be cleared.  */
 426           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 427               && (TYPE_PRECISION (TREE_TYPE (expr))
 428                   != GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)))))
 429             code = CONVERT_EXPR;
 430           else
 431             code = NOP_EXPR;
 432
 433           return build1 (code, type, expr);
 434         }
 435
 436       /* If TYPE is an enumeral type or a type with a precision less
 437          than the number of bits in its mode, do the conversion to the
 438          type corresponding to its mode, then do a nop conversion
 439          to TYPE.  */
 440       else if (TREE_CODE (type) == ENUMERAL_TYPE
 441                || outprec != GET_MODE_BITSIZE (TYPE_MODE (type)))
 442         return build1 (NOP_EXPR, type,
 443                        convert (lang_hooks.types.type_for_mode
 444                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 445                                 expr));
 446
 447       /* Here detect when we can distribute the truncation down past some
 448          arithmetic.  For example, if adding two longs and converting to an
 449          int, we can equally well convert both to ints and then add.
 450          For the operations handled here, such truncation distribution
 451          is always safe.
 452          It is desirable in these cases:
 453          1) when truncating down to full-word from a larger size
 454          2) when truncating takes no work.
 455          3) when at least one operand of the arithmetic has been extended
 456          (as by C's default conversions).  In this case we need two conversions
 457          if we do the arithmetic as already requested, so we might as well
 458          truncate both and then combine.  Perhaps that way we need only one.
 459
 460          Note that in general we cannot do the arithmetic in a type
 461          shorter than the desired result of conversion, even if the operands
 462          are both extended from a shorter type, because they might overflow
 463          if combined in that type.  The exceptions to this--the times when
 464          two narrow values can be combined in their narrow type even to
 465          make a wider result--are handled by "shorten" in build_binary_op.  */
 466
 467       switch (ex_form)
 468         {
 469         case RSHIFT_EXPR:
 470           /* We can pass truncation down through right shifting
 471              when the shift count is a nonpositive constant.  */
 472           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 473               && tree_int_cst_lt (TREE_OPERAND (expr, 1),
 474                                   convert (TREE_TYPE (TREE_OPERAND (expr, 1)),
 475                                            integer_one_node)))
 476             goto trunc1;
 477           break;
 478
 479         case LSHIFT_EXPR:
 480           /* We can pass truncation down through left shifting
 481              when the shift count is a nonnegative constant and
 482              the target type is unsigned.  */
 483           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 484               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 485               && TYPE_UNSIGNED (type)
 486               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 487             {
 488               /* If shift count is less than the width of the truncated type,
 489                  really shift.  */
 490               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 491                 /* In this case, shifting is like multiplication.  */
 492                 goto trunc1;
 493               else
 494                 {
 495                   /* If it is >= that width, result is zero.
 496                      Handling this with trunc1 would give the wrong result:
 497                      (int) ((long long) a << 32) is well defined (as 0)
 498                      but (int) a << 32 is undefined and would get a
 499                      warning.  */
 500
 501                   tree t = convert_to_integer (type, integer_zero_node);
 502
 503                   /* If the original expression had side-effects, we must
 504                      preserve it.  */
 505                   if (TREE_SIDE_EFFECTS (expr))
 506                     return build2 (COMPOUND_EXPR, type, expr, t);
 507                   else
 508                     return t;
 509                 }
 510             }
 511           break;
 512
 513         case MAX_EXPR:
 514         case MIN_EXPR:
 515         case MULT_EXPR:
 516           {
 517             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 518             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 519
 520             /* Don't distribute unless the output precision is at least as big
 521                as the actual inputs.  Otherwise, the comparison of the
 522                truncated values will be wrong.  */
 523             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 524                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 525                 /* If signedness of arg0 and arg1 don't match,
 526                    we can't necessarily find a type to compare them in.  */
 527                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 528                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 529               goto trunc1;
 530             break;
 531           }
 532
 533         case PLUS_EXPR:
 534         case MINUS_EXPR:
 535         case BIT_AND_EXPR:
 536         case BIT_IOR_EXPR:
 537         case BIT_XOR_EXPR:
 538         trunc1:
 539           {
 540             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 541             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 542
 543             if (outprec >= BITS_PER_WORD
 544                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 545                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 546                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 547               {
 548                 /* Do the arithmetic in type TYPEX,
 549                    then convert result to TYPE.  */
 550                 tree typex = type;
 551
 552                 /* Can't do arithmetic in enumeral types
 553                    so use an integer type that will hold the values.  */
 554                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 555                   typex = lang_hooks.types.type_for_size
 556                     (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 557
 558                 /* But now perhaps TYPEX is as wide as INPREC.
 559                    In that case, do nothing special here.
 560                    (Otherwise would recurse infinitely in convert.  */
 561                 if (TYPE_PRECISION (typex) != inprec)
 562                   {
 563                     /* Don't do unsigned arithmetic where signed was wanted,
 564                        or vice versa.
 565                        Exception: if both of the original operands were
 566                        unsigned then we can safely do the work as unsigned.
 567                        Exception: shift operations take their type solely
 568                        from the first argument.
 569                        Exception: the LSHIFT_EXPR case above requires that
 570                        we perform this operation unsigned lest we produce
 571                        signed-overflow undefinedness.
 572                        And we may need to do it as unsigned
 573                        if we truncate to the original size.  */
 574                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 575                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 576                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 577                                 || ex_form == LSHIFT_EXPR
 578                                 || ex_form == RSHIFT_EXPR
 579                                 || ex_form == LROTATE_EXPR
 580                                 || ex_form == RROTATE_EXPR))
 581                         || ex_form == LSHIFT_EXPR)
 582                       typex = lang_hooks.types.unsigned_type (typex);
 583                     else
 584                       typex = lang_hooks.types.signed_type (typex);
 585                     return convert (type,
 586                                     fold (build2 (ex_form, typex,
 587                                                   convert (typex, arg0),
 588                                                   convert (typex, arg1))));
 589                   }
 590               }
 591           }
 592           break;
 593
 594         case NEGATE_EXPR:
 595         case BIT_NOT_EXPR:
 596           /* This is not correct for ABS_EXPR,
 597              since we must test the sign before truncation.  */
 598           {
 599             tree typex = type;
 600
 601             /* Can't do arithmetic in enumeral types
 602                so use an integer type that will hold the values.  */
 603             if (TREE_CODE (typex) == ENUMERAL_TYPE)
 604               typex = lang_hooks.types.type_for_size
 605                 (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 606
 607             /* But now perhaps TYPEX is as wide as INPREC.
 608                In that case, do nothing special here.
 609                (Otherwise would recurse infinitely in convert.  */
 610             if (TYPE_PRECISION (typex) != inprec)
 611               {
 612                 /* Don't do unsigned arithmetic where signed was wanted,
 613                    or vice versa.  */
 614                 if (TYPE_UNSIGNED (TREE_TYPE (expr)))
 615                   typex = lang_hooks.types.unsigned_type (typex);
 616                 else
 617                   typex = lang_hooks.types.signed_type (typex);
 618                 return convert (type,
 619                                 fold (build1 (ex_form, typex,
 620                                               convert (typex,
 621                                                        TREE_OPERAND (expr, 0)))));
 622               }
 623           }
 624
 625         case NOP_EXPR:
 626           /* Don't introduce a
 627              "can't convert between vector values of different size" error.  */
 628           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 629               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 630                   != GET_MODE_SIZE (TYPE_MODE (type))))
 631             break;
 632           /* If truncating after truncating, might as well do all at once.
 633              If truncating after extending, we may get rid of wasted work.  */
 634           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 635
 636         case COND_EXPR:
 637           /* It is sometimes worthwhile to push the narrowing down through
 638              the conditional and never loses.  */
 639           return fold (build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 640                                convert (type, TREE_OPERAND (expr, 1)),
 641                                convert (type, TREE_OPERAND (expr, 2))));
 642
 643         default:
 644           break;
 645         }
 646
 647       return build1 (CONVERT_EXPR, type, expr);
 648
 649     case REAL_TYPE:
 650       return build1 (FIX_TRUNC_EXPR, type, expr);
 651
 652     case COMPLEX_TYPE:
 653       return convert (type,
 654                       fold (build1 (REALPART_EXPR,
 655                                     TREE_TYPE (TREE_TYPE (expr)), expr)));
 656
 657     case VECTOR_TYPE:
 658       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 659         {
 660           error ("can't convert between vector values of different size");
 661           return error_mark_node;
 662         }
 663       return build1 (NOP_EXPR, type, expr);
 664
 665     default:
 666       error ("aggregate value used where an integer was expected");
 667       return convert (type, integer_zero_node);
 668     }
 669 }
 670
 671 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 672
 673 tree
 674 convert_to_complex (tree type, tree expr)
 675 {
 676   tree subtype = TREE_TYPE (type);
 677
 678   switch (TREE_CODE (TREE_TYPE (expr)))
 679     {
 680     case REAL_TYPE:
 681     case INTEGER_TYPE:
 682     case ENUMERAL_TYPE:
 683     case BOOLEAN_TYPE:
 684     case CHAR_TYPE:
 685       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 686                      convert (subtype, integer_zero_node));
 687
 688     case COMPLEX_TYPE:
 689       {
 690         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 691
 692         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 693           return expr;
 694         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 695           return fold (build2 (COMPLEX_EXPR, type,
 696                                convert (subtype, TREE_OPERAND (expr, 0)),
 697                                convert (subtype, TREE_OPERAND (expr, 1))));
 698         else
 699           {
 700             expr = save_expr (expr);
 701             return
 702               fold (build2 (COMPLEX_EXPR, type,
 703                             convert (subtype,
 704                                      fold (build1 (REALPART_EXPR,
 705                                                    TREE_TYPE (TREE_TYPE (expr)),
 706                                                    expr))),
 707                             convert (subtype,
 708                                      fold (build1 (IMAGPART_EXPR,
 709                                                    TREE_TYPE (TREE_TYPE (expr)),
 710                                                    expr)))));
 711           }
 712       }
 713
 714     case POINTER_TYPE:
 715     case REFERENCE_TYPE:
 716       error ("pointer value used where a complex was expected");
 717       return convert_to_complex (type, integer_zero_node);
 718
 719     default:
 720       error ("aggregate value used where a complex was expected");
 721       return convert_to_complex (type, integer_zero_node);
 722     }
 723 }
 724
 725 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 726
 727 tree
 728 convert_to_vector (tree type, tree expr)
 729 {
 730   switch (TREE_CODE (TREE_TYPE (expr)))
 731     {
 732     case INTEGER_TYPE:
 733     case VECTOR_TYPE:
 734       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 735         {
 736           error ("can't convert between vector values of different size");
 737           return error_mark_node;
 738         }
 739       return build1 (NOP_EXPR, type, expr);
 740
 741     default:
 742       error ("can't convert value to a vector");
 743       return error_mark_node;
 744     }
 745 }