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, 2006 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 (outprec < TYPE_PRECISION (long_integer_type_node)
 354               || (outprec == TYPE_PRECISION (long_integer_type_node)
 355                   && !TYPE_UNSIGNED (type)))
 356             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 357           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 358                    && !TYPE_UNSIGNED (type))
 359             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 360           break;
 361
 362         case BUILT_IN_RINT: case BUILT_IN_RINTF: case BUILT_IN_RINTL:
 363           /* Only convert rint* if we can ignore math exceptions.  */
 364           if (flag_trapping_math)
 365             break;
 366           /* ... Fall through ...  */
 367         case BUILT_IN_NEARBYINT:
 368         case BUILT_IN_NEARBYINTF:
 369         case BUILT_IN_NEARBYINTL:
 370           if (outprec < TYPE_PRECISION (long_integer_type_node)
 371               || (outprec == TYPE_PRECISION (long_integer_type_node)
 372                   && !TYPE_UNSIGNED (type)))
 373             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 374           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 375                    && !TYPE_UNSIGNED (type))
 376             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 377           break;
 378         default:
 379           break;
 380         }
 381
 382       if (fn)
 383         {
 384           tree arglist = TREE_OPERAND (s_expr, 1);
 385           tree newexpr = build_function_call_expr (fn, arglist);
 386           return convert_to_integer (type, newexpr);
 387         }
 388     }
 389
 390   switch (TREE_CODE (intype))
 391     {
 392     case POINTER_TYPE:
 393     case REFERENCE_TYPE:
 394       if (integer_zerop (expr))
 395         expr = integer_zero_node;
 396       else
 397         expr = fold (build1 (CONVERT_EXPR,
 398                              lang_hooks.types.type_for_size (POINTER_SIZE, 0),
 399                              expr));
 400
 401       return convert_to_integer (type, expr);
 402
 403     case INTEGER_TYPE:
 404     case ENUMERAL_TYPE:
 405     case BOOLEAN_TYPE:
 406     case CHAR_TYPE:
 407       /* If this is a logical operation, which just returns 0 or 1, we can
 408          change the type of the expression.  */
 409
 410       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 411         {
 412           expr = copy_node (expr);
 413           TREE_TYPE (expr) = type;
 414           return expr;
 415         }
 416
 417       /* If we are widening the type, put in an explicit conversion.
 418          Similarly if we are not changing the width.  After this, we know
 419          we are truncating EXPR.  */
 420
 421       else if (outprec >= inprec)
 422         {
 423           enum tree_code code;
 424
 425           /* If the precision of the EXPR's type is K bits and the
 426              destination mode has more bits, and the sign is changing,
 427              it is not safe to use a NOP_EXPR.  For example, suppose
 428              that EXPR's type is a 3-bit unsigned integer type, the
 429              TYPE is a 3-bit signed integer type, and the machine mode
 430              for the types is 8-bit QImode.  In that case, the
 431              conversion necessitates an explicit sign-extension.  In
 432              the signed-to-unsigned case the high-order bits have to
 433              be cleared.  */
 434           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 435               && (TYPE_PRECISION (TREE_TYPE (expr))
 436                   != GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)))))
 437             code = CONVERT_EXPR;
 438           else
 439             code = NOP_EXPR;
 440
 441           return build1 (code, type, expr);
 442         }
 443
 444       /* If TYPE is an enumeral type or a type with a precision less
 445          than the number of bits in its mode, do the conversion to the
 446          type corresponding to its mode, then do a nop conversion
 447          to TYPE.  */
 448       else if (TREE_CODE (type) == ENUMERAL_TYPE
 449                || outprec != GET_MODE_BITSIZE (TYPE_MODE (type)))
 450         return build1 (NOP_EXPR, type,
 451                        convert (lang_hooks.types.type_for_mode
 452                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 453                                 expr));
 454
 455       /* Here detect when we can distribute the truncation down past some
 456          arithmetic.  For example, if adding two longs and converting to an
 457          int, we can equally well convert both to ints and then add.
 458          For the operations handled here, such truncation distribution
 459          is always safe.
 460          It is desirable in these cases:
 461          1) when truncating down to full-word from a larger size
 462          2) when truncating takes no work.
 463          3) when at least one operand of the arithmetic has been extended
 464          (as by C's default conversions).  In this case we need two conversions
 465          if we do the arithmetic as already requested, so we might as well
 466          truncate both and then combine.  Perhaps that way we need only one.
 467
 468          Note that in general we cannot do the arithmetic in a type
 469          shorter than the desired result of conversion, even if the operands
 470          are both extended from a shorter type, because they might overflow
 471          if combined in that type.  The exceptions to this--the times when
 472          two narrow values can be combined in their narrow type even to
 473          make a wider result--are handled by "shorten" in build_binary_op.  */
 474
 475       switch (ex_form)
 476         {
 477         case RSHIFT_EXPR:
 478           /* We can pass truncation down through right shifting
 479              when the shift count is a nonpositive constant.  */
 480           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 481               && tree_int_cst_lt (TREE_OPERAND (expr, 1),
 482                                   convert (TREE_TYPE (TREE_OPERAND (expr, 1)),
 483                                            integer_one_node)))
 484             goto trunc1;
 485           break;
 486
 487         case LSHIFT_EXPR:
 488           /* We can pass truncation down through left shifting
 489              when the shift count is a nonnegative constant and
 490              the target type is unsigned.  */
 491           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 492               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 493               && TYPE_UNSIGNED (type)
 494               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 495             {
 496               /* If shift count is less than the width of the truncated type,
 497                  really shift.  */
 498               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 499                 /* In this case, shifting is like multiplication.  */
 500                 goto trunc1;
 501               else
 502                 {
 503                   /* If it is >= that width, result is zero.
 504                      Handling this with trunc1 would give the wrong result:
 505                      (int) ((long long) a << 32) is well defined (as 0)
 506                      but (int) a << 32 is undefined and would get a
 507                      warning.  */
 508
 509                   tree t = convert_to_integer (type, integer_zero_node);
 510
 511                   /* If the original expression had side-effects, we must
 512                      preserve it.  */
 513                   if (TREE_SIDE_EFFECTS (expr))
 514                     return build2 (COMPOUND_EXPR, type, expr, t);
 515                   else
 516                     return t;
 517                 }
 518             }
 519           break;
 520
 521         case MAX_EXPR:
 522         case MIN_EXPR:
 523         case MULT_EXPR:
 524           {
 525             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 526             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 527
 528             /* Don't distribute unless the output precision is at least as big
 529                as the actual inputs.  Otherwise, the comparison of the
 530                truncated values will be wrong.  */
 531             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 532                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 533                 /* If signedness of arg0 and arg1 don't match,
 534                    we can't necessarily find a type to compare them in.  */
 535                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 536                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 537               goto trunc1;
 538             break;
 539           }
 540
 541         case PLUS_EXPR:
 542         case MINUS_EXPR:
 543         case BIT_AND_EXPR:
 544         case BIT_IOR_EXPR:
 545         case BIT_XOR_EXPR:
 546         trunc1:
 547           {
 548             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 549             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 550
 551             if (outprec >= BITS_PER_WORD
 552                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 553                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 554                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 555               {
 556                 /* Do the arithmetic in type TYPEX,
 557                    then convert result to TYPE.  */
 558                 tree typex = type;
 559
 560                 /* Can't do arithmetic in enumeral types
 561                    so use an integer type that will hold the values.  */
 562                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 563                   typex = lang_hooks.types.type_for_size
 564                     (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 565
 566                 /* But now perhaps TYPEX is as wide as INPREC.
 567                    In that case, do nothing special here.
 568                    (Otherwise would recurse infinitely in convert.  */
 569                 if (TYPE_PRECISION (typex) != inprec)
 570                   {
 571                     /* Don't do unsigned arithmetic where signed was wanted,
 572                        or vice versa.
 573                        Exception: if both of the original operands were
 574                        unsigned then we can safely do the work as unsigned.
 575                        Exception: shift operations take their type solely
 576                        from the first argument.
 577                        Exception: the LSHIFT_EXPR case above requires that
 578                        we perform this operation unsigned lest we produce
 579                        signed-overflow undefinedness.
 580                        And we may need to do it as unsigned
 581                        if we truncate to the original size.  */
 582                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 583                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 584                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 585                                 || ex_form == LSHIFT_EXPR
 586                                 || ex_form == RSHIFT_EXPR
 587                                 || ex_form == LROTATE_EXPR
 588                                 || ex_form == RROTATE_EXPR))
 589                         || ex_form == LSHIFT_EXPR)
 590                       typex = lang_hooks.types.unsigned_type (typex);
 591                     else
 592                       typex = lang_hooks.types.signed_type (typex);
 593                     return convert (type,
 594                                     fold (build2 (ex_form, typex,
 595                                                   convert (typex, arg0),
 596                                                   convert (typex, arg1))));
 597                   }
 598               }
 599           }
 600           break;
 601
 602         case NEGATE_EXPR:
 603         case BIT_NOT_EXPR:
 604           /* This is not correct for ABS_EXPR,
 605              since we must test the sign before truncation.  */
 606           {
 607             tree typex = type;
 608
 609             /* Can't do arithmetic in enumeral types
 610                so use an integer type that will hold the values.  */
 611             if (TREE_CODE (typex) == ENUMERAL_TYPE)
 612               typex = lang_hooks.types.type_for_size
 613                 (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 614
 615             /* But now perhaps TYPEX is as wide as INPREC.
 616                In that case, do nothing special here.
 617                (Otherwise would recurse infinitely in convert.  */
 618             if (TYPE_PRECISION (typex) != inprec)
 619               {
 620                 /* Don't do unsigned arithmetic where signed was wanted,
 621                    or vice versa.  */
 622                 if (TYPE_UNSIGNED (TREE_TYPE (expr)))
 623                   typex = lang_hooks.types.unsigned_type (typex);
 624                 else
 625                   typex = lang_hooks.types.signed_type (typex);
 626                 return convert (type,
 627                                 fold (build1 (ex_form, typex,
 628                                               convert (typex,
 629                                                        TREE_OPERAND (expr, 0)))));
 630               }
 631           }
 632
 633         case NOP_EXPR:
 634           /* Don't introduce a
 635              "can't convert between vector values of different size" error.  */
 636           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 637               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 638                   != GET_MODE_SIZE (TYPE_MODE (type))))
 639             break;
 640           /* If truncating after truncating, might as well do all at once.
 641              If truncating after extending, we may get rid of wasted work.  */
 642           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 643
 644         case COND_EXPR:
 645           /* It is sometimes worthwhile to push the narrowing down through
 646              the conditional and never loses.  */
 647           return fold (build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 648                                convert (type, TREE_OPERAND (expr, 1)),
 649                                convert (type, TREE_OPERAND (expr, 2))));
 650
 651         default:
 652           break;
 653         }
 654
 655       return build1 (CONVERT_EXPR, type, expr);
 656
 657     case REAL_TYPE:
 658       return build1 (FIX_TRUNC_EXPR, type, expr);
 659
 660     case COMPLEX_TYPE:
 661       return convert (type,
 662                       fold (build1 (REALPART_EXPR,
 663                                     TREE_TYPE (TREE_TYPE (expr)), expr)));
 664
 665     case VECTOR_TYPE:
 666       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 667         {
 668           error ("can't convert between vector values of different size");
 669           return error_mark_node;
 670         }
 671       return build1 (VIEW_CONVERT_EXPR, type, expr);
 672
 673     default:
 674       error ("aggregate value used where an integer was expected");
 675       return convert (type, integer_zero_node);
 676     }
 677 }
 678
 679 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 680
 681 tree
 682 convert_to_complex (tree type, tree expr)
 683 {
 684   tree subtype = TREE_TYPE (type);
 685
 686   switch (TREE_CODE (TREE_TYPE (expr)))
 687     {
 688     case REAL_TYPE:
 689     case INTEGER_TYPE:
 690     case ENUMERAL_TYPE:
 691     case BOOLEAN_TYPE:
 692     case CHAR_TYPE:
 693       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 694                      convert (subtype, integer_zero_node));
 695
 696     case COMPLEX_TYPE:
 697       {
 698         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 699
 700         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 701           return expr;
 702         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 703           return fold (build2 (COMPLEX_EXPR, type,
 704                                convert (subtype, TREE_OPERAND (expr, 0)),
 705                                convert (subtype, TREE_OPERAND (expr, 1))));
 706         else
 707           {
 708             expr = save_expr (expr);
 709             return
 710               fold (build2 (COMPLEX_EXPR, type,
 711                             convert (subtype,
 712                                      fold (build1 (REALPART_EXPR,
 713                                                    TREE_TYPE (TREE_TYPE (expr)),
 714                                                    expr))),
 715                             convert (subtype,
 716                                      fold (build1 (IMAGPART_EXPR,
 717                                                    TREE_TYPE (TREE_TYPE (expr)),
 718                                                    expr)))));
 719           }
 720       }
 721
 722     case POINTER_TYPE:
 723     case REFERENCE_TYPE:
 724       error ("pointer value used where a complex was expected");
 725       return convert_to_complex (type, integer_zero_node);
 726
 727     default:
 728       error ("aggregate value used where a complex was expected");
 729       return convert_to_complex (type, integer_zero_node);
 730     }
 731 }
 732
 733 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 734
 735 tree
 736 convert_to_vector (tree type, tree expr)
 737 {
 738   switch (TREE_CODE (TREE_TYPE (expr)))
 739     {
 740     case INTEGER_TYPE:
 741     case VECTOR_TYPE:
 742       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 743         {
 744           error ("can't convert between vector values of different size");
 745           return error_mark_node;
 746         }
 747       return build1 (VIEW_CONVERT_EXPR, type, expr);
 748
 749     default:
 750       error ("can't convert value to a vector");
 751       return error_mark_node;
 752     }
 753 }