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_FLOOR: case BUILT_IN_FLOORF: case BUILT_IN_FLOORL:
 353           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 354             fn = mathfn_built_in (s_intype, BUILT_IN_LLFLOOR);
 355           else
 356             fn = mathfn_built_in (s_intype, BUILT_IN_LFLOOR);
 357           break;
 358
 359         case BUILT_IN_ROUND: case BUILT_IN_ROUNDF: case BUILT_IN_ROUNDL:
 360           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 361             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 362           else
 363             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 364           break;
 365
 366         case BUILT_IN_RINT: case BUILT_IN_RINTF: case BUILT_IN_RINTL:
 367           /* Only convert rint* if we can ignore math exceptions.  */
 368           if (flag_trapping_math)
 369             break;
 370           /* ... Fall through ...  */
 371         case BUILT_IN_NEARBYINT: case BUILT_IN_NEARBYINTF: case BUILT_IN_NEARBYINTL:
 372           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 373             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 374           else
 375             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 376           break;
 377         default:
 378           break;
 379         }
 380
 381       if (fn)
 382         {
 383           tree arglist = TREE_OPERAND (s_expr, 1);
 384           tree newexpr = build_function_call_expr (fn, arglist);
 385           return convert_to_integer (type, newexpr);
 386         }
 387     }
 388
 389   switch (TREE_CODE (intype))
 390     {
 391     case POINTER_TYPE:
 392     case REFERENCE_TYPE:
 393       if (integer_zerop (expr))
 394         expr = integer_zero_node;
 395       else
 396         expr = fold (build1 (CONVERT_EXPR,
 397                              lang_hooks.types.type_for_size (POINTER_SIZE, 0),
 398                              expr));
 399
 400       return convert_to_integer (type, expr);
 401
 402     case INTEGER_TYPE:
 403     case ENUMERAL_TYPE:
 404     case BOOLEAN_TYPE:
 405     case CHAR_TYPE:
 406       /* If this is a logical operation, which just returns 0 or 1, we can
 407          change the type of the expression.  */
 408
 409       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 410         {
 411           expr = copy_node (expr);
 412           TREE_TYPE (expr) = type;
 413           return expr;
 414         }
 415
 416       /* If we are widening the type, put in an explicit conversion.
 417          Similarly if we are not changing the width.  After this, we know
 418          we are truncating EXPR.  */
 419
 420       else if (outprec >= inprec)
 421         {
 422           enum tree_code code;
 423
 424           /* If the precision of the EXPR's type is K bits and the
 425              destination mode has more bits, and the sign is changing,
 426              it is not safe to use a NOP_EXPR.  For example, suppose
 427              that EXPR's type is a 3-bit unsigned integer type, the
 428              TYPE is a 3-bit signed integer type, and the machine mode
 429              for the types is 8-bit QImode.  In that case, the
 430              conversion necessitates an explicit sign-extension.  In
 431              the signed-to-unsigned case the high-order bits have to
 432              be cleared.  */
 433           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 434               && (TYPE_PRECISION (TREE_TYPE (expr))
 435                   != GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)))))
 436             code = CONVERT_EXPR;
 437           else
 438             code = NOP_EXPR;
 439
 440           return build1 (code, type, expr);
 441         }
 442
 443       /* If TYPE is an enumeral type or a type with a precision less
 444          than the number of bits in its mode, do the conversion to the
 445          type corresponding to its mode, then do a nop conversion
 446          to TYPE.  */
 447       else if (TREE_CODE (type) == ENUMERAL_TYPE
 448                || outprec != GET_MODE_BITSIZE (TYPE_MODE (type)))
 449         return build1 (NOP_EXPR, type,
 450                        convert (lang_hooks.types.type_for_mode
 451                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 452                                 expr));
 453
 454       /* Here detect when we can distribute the truncation down past some
 455          arithmetic.  For example, if adding two longs and converting to an
 456          int, we can equally well convert both to ints and then add.
 457          For the operations handled here, such truncation distribution
 458          is always safe.
 459          It is desirable in these cases:
 460          1) when truncating down to full-word from a larger size
 461          2) when truncating takes no work.
 462          3) when at least one operand of the arithmetic has been extended
 463          (as by C's default conversions).  In this case we need two conversions
 464          if we do the arithmetic as already requested, so we might as well
 465          truncate both and then combine.  Perhaps that way we need only one.
 466
 467          Note that in general we cannot do the arithmetic in a type
 468          shorter than the desired result of conversion, even if the operands
 469          are both extended from a shorter type, because they might overflow
 470          if combined in that type.  The exceptions to this--the times when
 471          two narrow values can be combined in their narrow type even to
 472          make a wider result--are handled by "shorten" in build_binary_op.  */
 473
 474       switch (ex_form)
 475         {
 476         case RSHIFT_EXPR:
 477           /* We can pass truncation down through right shifting
 478              when the shift count is a nonpositive constant.  */
 479           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 480               && tree_int_cst_lt (TREE_OPERAND (expr, 1),
 481                                   convert (TREE_TYPE (TREE_OPERAND (expr, 1)),
 482                                            integer_one_node)))
 483             goto trunc1;
 484           break;
 485
 486         case LSHIFT_EXPR:
 487           /* We can pass truncation down through left shifting
 488              when the shift count is a nonnegative constant and
 489              the target type is unsigned.  */
 490           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 491               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 492               && TYPE_UNSIGNED (type)
 493               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 494             {
 495               /* If shift count is less than the width of the truncated type,
 496                  really shift.  */
 497               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 498                 /* In this case, shifting is like multiplication.  */
 499                 goto trunc1;
 500               else
 501                 {
 502                   /* If it is >= that width, result is zero.
 503                      Handling this with trunc1 would give the wrong result:
 504                      (int) ((long long) a << 32) is well defined (as 0)
 505                      but (int) a << 32 is undefined and would get a
 506                      warning.  */
 507
 508                   tree t = convert_to_integer (type, integer_zero_node);
 509
 510                   /* If the original expression had side-effects, we must
 511                      preserve it.  */
 512                   if (TREE_SIDE_EFFECTS (expr))
 513                     return build2 (COMPOUND_EXPR, type, expr, t);
 514                   else
 515                     return t;
 516                 }
 517             }
 518           break;
 519
 520         case MAX_EXPR:
 521         case MIN_EXPR:
 522         case MULT_EXPR:
 523           {
 524             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 525             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 526
 527             /* Don't distribute unless the output precision is at least as big
 528                as the actual inputs.  Otherwise, the comparison of the
 529                truncated values will be wrong.  */
 530             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 531                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 532                 /* If signedness of arg0 and arg1 don't match,
 533                    we can't necessarily find a type to compare them in.  */
 534                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 535                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 536               goto trunc1;
 537             break;
 538           }
 539
 540         case PLUS_EXPR:
 541         case MINUS_EXPR:
 542         case BIT_AND_EXPR:
 543         case BIT_IOR_EXPR:
 544         case BIT_XOR_EXPR:
 545         trunc1:
 546           {
 547             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 548             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 549
 550             if (outprec >= BITS_PER_WORD
 551                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 552                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 553                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 554               {
 555                 /* Do the arithmetic in type TYPEX,
 556                    then convert result to TYPE.  */
 557                 tree typex = type;
 558
 559                 /* Can't do arithmetic in enumeral types
 560                    so use an integer type that will hold the values.  */
 561                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 562                   typex = lang_hooks.types.type_for_size
 563                     (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 564
 565                 /* But now perhaps TYPEX is as wide as INPREC.
 566                    In that case, do nothing special here.
 567                    (Otherwise would recurse infinitely in convert.  */
 568                 if (TYPE_PRECISION (typex) != inprec)
 569                   {
 570                     /* Don't do unsigned arithmetic where signed was wanted,
 571                        or vice versa.
 572                        Exception: if both of the original operands were
 573                        unsigned then we can safely do the work as unsigned.
 574                        Exception: shift operations take their type solely
 575                        from the first argument.
 576                        Exception: the LSHIFT_EXPR case above requires that
 577                        we perform this operation unsigned lest we produce
 578                        signed-overflow undefinedness.
 579                        And we may need to do it as unsigned
 580                        if we truncate to the original size.  */
 581                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 582                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 583                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 584                                 || ex_form == LSHIFT_EXPR
 585                                 || ex_form == RSHIFT_EXPR
 586                                 || ex_form == LROTATE_EXPR
 587                                 || ex_form == RROTATE_EXPR))
 588                         || ex_form == LSHIFT_EXPR)
 589                       typex = lang_hooks.types.unsigned_type (typex);
 590                     else
 591                       typex = lang_hooks.types.signed_type (typex);
 592                     return convert (type,
 593                                     fold (build2 (ex_form, typex,
 594                                                   convert (typex, arg0),
 595                                                   convert (typex, arg1))));
 596                   }
 597               }
 598           }
 599           break;
 600
 601         case NEGATE_EXPR:
 602         case BIT_NOT_EXPR:
 603           /* This is not correct for ABS_EXPR,
 604              since we must test the sign before truncation.  */
 605           {
 606             tree typex = type;
 607
 608             /* Can't do arithmetic in enumeral types
 609                so use an integer type that will hold the values.  */
 610             if (TREE_CODE (typex) == ENUMERAL_TYPE)
 611               typex = lang_hooks.types.type_for_size
 612                 (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 613
 614             /* But now perhaps TYPEX is as wide as INPREC.
 615                In that case, do nothing special here.
 616                (Otherwise would recurse infinitely in convert.  */
 617             if (TYPE_PRECISION (typex) != inprec)
 618               {
 619                 /* Don't do unsigned arithmetic where signed was wanted,
 620                    or vice versa.  */
 621                 if (TYPE_UNSIGNED (TREE_TYPE (expr)))
 622                   typex = lang_hooks.types.unsigned_type (typex);
 623                 else
 624                   typex = lang_hooks.types.signed_type (typex);
 625                 return convert (type,
 626                                 fold (build1 (ex_form, typex,
 627                                               convert (typex,
 628                                                        TREE_OPERAND (expr, 0)))));
 629               }
 630           }
 631
 632         case NOP_EXPR:
 633           /* Don't introduce a
 634              "can't convert between vector values of different size" error.  */
 635           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 636               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 637                   != GET_MODE_SIZE (TYPE_MODE (type))))
 638             break;
 639           /* If truncating after truncating, might as well do all at once.
 640              If truncating after extending, we may get rid of wasted work.  */
 641           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 642
 643         case COND_EXPR:
 644           /* It is sometimes worthwhile to push the narrowing down through
 645              the conditional and never loses.  */
 646           return fold (build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 647                                convert (type, TREE_OPERAND (expr, 1)),
 648                                convert (type, TREE_OPERAND (expr, 2))));
 649
 650         default:
 651           break;
 652         }
 653
 654       return build1 (CONVERT_EXPR, type, expr);
 655
 656     case REAL_TYPE:
 657       return build1 (FIX_TRUNC_EXPR, type, expr);
 658
 659     case COMPLEX_TYPE:
 660       return convert (type,
 661                       fold (build1 (REALPART_EXPR,
 662                                     TREE_TYPE (TREE_TYPE (expr)), expr)));
 663
 664     case VECTOR_TYPE:
 665       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 666         {
 667           error ("can't convert between vector values of different size");
 668           return error_mark_node;
 669         }
 670       return build1 (NOP_EXPR, type, expr);
 671
 672     default:
 673       error ("aggregate value used where an integer was expected");
 674       return convert (type, integer_zero_node);
 675     }
 676 }
 677
 678 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 679
 680 tree
 681 convert_to_complex (tree type, tree expr)
 682 {
 683   tree subtype = TREE_TYPE (type);
 684
 685   switch (TREE_CODE (TREE_TYPE (expr)))
 686     {
 687     case REAL_TYPE:
 688     case INTEGER_TYPE:
 689     case ENUMERAL_TYPE:
 690     case BOOLEAN_TYPE:
 691     case CHAR_TYPE:
 692       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 693                      convert (subtype, integer_zero_node));
 694
 695     case COMPLEX_TYPE:
 696       {
 697         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 698
 699         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 700           return expr;
 701         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 702           return fold (build2 (COMPLEX_EXPR, type,
 703                                convert (subtype, TREE_OPERAND (expr, 0)),
 704                                convert (subtype, TREE_OPERAND (expr, 1))));
 705         else
 706           {
 707             expr = save_expr (expr);
 708             return
 709               fold (build2 (COMPLEX_EXPR, type,
 710                             convert (subtype,
 711                                      fold (build1 (REALPART_EXPR,
 712                                                    TREE_TYPE (TREE_TYPE (expr)),
 713                                                    expr))),
 714                             convert (subtype,
 715                                      fold (build1 (IMAGPART_EXPR,
 716                                                    TREE_TYPE (TREE_TYPE (expr)),
 717                                                    expr)))));
 718           }
 719       }
 720
 721     case POINTER_TYPE:
 722     case REFERENCE_TYPE:
 723       error ("pointer value used where a complex was expected");
 724       return convert_to_complex (type, integer_zero_node);
 725
 726     default:
 727       error ("aggregate value used where a complex was expected");
 728       return convert_to_complex (type, integer_zero_node);
 729     }
 730 }
 731
 732 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 733
 734 tree
 735 convert_to_vector (tree type, tree expr)
 736 {
 737   switch (TREE_CODE (TREE_TYPE (expr)))
 738     {
 739     case INTEGER_TYPE:
 740     case VECTOR_TYPE:
 741       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 742         {
 743           error ("can't convert between vector values of different size");
 744           return error_mark_node;
 745         }
 746       return build1 (NOP_EXPR, type, expr);
 747
 748     default:
 749       error ("can't convert value to a vector");
 750       return error_mark_node;
 751     }
 752 }