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 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_2 (0, 0);
  47       TREE_TYPE (expr) = type;
  48       return expr;
  49     }
  50
  51   switch (TREE_CODE (TREE_TYPE (expr)))
  52     {
  53     case POINTER_TYPE:
  54     case REFERENCE_TYPE:
  55       return build1 (NOP_EXPR, type, expr);
  56
  57     case INTEGER_TYPE:
  58     case ENUMERAL_TYPE:
  59     case BOOLEAN_TYPE:
  60     case CHAR_TYPE:
  61       if (TYPE_PRECISION (TREE_TYPE (expr)) == POINTER_SIZE)
  62         return build1 (CONVERT_EXPR, type, expr);
  63
  64       return
  65         convert_to_pointer (type,
  66                             convert (lang_hooks.types.type_for_size
  67                                      (POINTER_SIZE, 0), expr));
  68
  69     default:
  70       error ("cannot convert to a pointer type");
  71       return convert_to_pointer (type, integer_zero_node);
  72     }
  73 }
  74
  75 /* Avoid any floating point extensions from EXP.  */
  76 tree
  77 strip_float_extensions (tree exp)
  78 {
  79   tree sub, expt, subt;
  80
  81   /*  For floating point constant look up the narrowest type that can hold
  82       it properly and handle it like (type)(narrowest_type)constant.
  83       This way we can optimize for instance a=a*2.0 where "a" is float
  84       but 2.0 is double constant.  */
  85   if (TREE_CODE (exp) == REAL_CST)
  86     {
  87       REAL_VALUE_TYPE orig;
  88       tree type = NULL;
  89
  90       orig = TREE_REAL_CST (exp);
  91       if (TYPE_PRECISION (TREE_TYPE (exp)) > TYPE_PRECISION (float_type_node)
  92           && exact_real_truncate (TYPE_MODE (float_type_node), &orig))
  93         type = float_type_node;
  94       else if (TYPE_PRECISION (TREE_TYPE (exp))
  95                > TYPE_PRECISION (double_type_node)
  96                && exact_real_truncate (TYPE_MODE (double_type_node), &orig))
  97         type = double_type_node;
  98       if (type)
  99         return build_real (type, real_value_truncate (TYPE_MODE (type), orig));
 100     }
 101
 102   if (TREE_CODE (exp) != NOP_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 = build (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.  For some logical operations,
 401          we must also change the types of the operands to maintain type
 402          correctness.  */
 403
 404       if (TREE_CODE_CLASS (ex_form) == '<')
 405         {
 406           expr = copy_node (expr);
 407           TREE_TYPE (expr) = type;
 408           return expr;
 409         }
 410
 411       else if (ex_form == TRUTH_AND_EXPR || ex_form == TRUTH_ANDIF_EXPR
 412                || ex_form == TRUTH_OR_EXPR || ex_form == TRUTH_ORIF_EXPR
 413                || ex_form == TRUTH_XOR_EXPR)
 414         {
 415           expr = copy_node (expr);
 416           TREE_OPERAND (expr, 0) = convert (type, TREE_OPERAND (expr, 0));
 417           TREE_OPERAND (expr, 1) = convert (type, TREE_OPERAND (expr, 1));
 418           TREE_TYPE (expr) = type;
 419           return expr;
 420         }
 421
 422       else if (ex_form == TRUTH_NOT_EXPR)
 423         {
 424           expr = copy_node (expr);
 425           TREE_OPERAND (expr, 0) = convert (type, TREE_OPERAND (expr, 0));
 426           TREE_TYPE (expr) = type;
 427           return expr;
 428         }
 429
 430       /* If we are widening the type, put in an explicit conversion.
 431          Similarly if we are not changing the width.  After this, we know
 432          we are truncating EXPR.  */
 433
 434       else if (outprec >= inprec)
 435         {
 436           enum tree_code code;
 437
 438           /* If the precision of the EXPR's type is K bits and the
 439              destination mode has more bits, and the sign is changing,
 440              it is not safe to use a NOP_EXPR.  For example, suppose
 441              that EXPR's type is a 3-bit unsigned integer type, the
 442              TYPE is a 3-bit signed integer type, and the machine mode
 443              for the types is 8-bit QImode.  In that case, the
 444              conversion necessitates an explicit sign-extension.  In
 445              the signed-to-unsigned case the high-order bits have to
 446              be cleared.  */
 447           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 448               && (TYPE_PRECISION (TREE_TYPE (expr))
 449                   != GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)))))
 450             code = CONVERT_EXPR;
 451           else
 452             code = NOP_EXPR;
 453
 454           return build1 (code, type, expr);
 455         }
 456
 457       /* If TYPE is an enumeral type or a type with a precision less
 458          than the number of bits in its mode, do the conversion to the
 459          type corresponding to its mode, then do a nop conversion
 460          to TYPE.  */
 461       else if (TREE_CODE (type) == ENUMERAL_TYPE
 462                || outprec != GET_MODE_BITSIZE (TYPE_MODE (type)))
 463         return build1 (NOP_EXPR, type,
 464                        convert (lang_hooks.types.type_for_mode
 465                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 466                                 expr));
 467
 468       /* Here detect when we can distribute the truncation down past some
 469          arithmetic.  For example, if adding two longs and converting to an
 470          int, we can equally well convert both to ints and then add.
 471          For the operations handled here, such truncation distribution
 472          is always safe.
 473          It is desirable in these cases:
 474          1) when truncating down to full-word from a larger size
 475          2) when truncating takes no work.
 476          3) when at least one operand of the arithmetic has been extended
 477          (as by C's default conversions).  In this case we need two conversions
 478          if we do the arithmetic as already requested, so we might as well
 479          truncate both and then combine.  Perhaps that way we need only one.
 480
 481          Note that in general we cannot do the arithmetic in a type
 482          shorter than the desired result of conversion, even if the operands
 483          are both extended from a shorter type, because they might overflow
 484          if combined in that type.  The exceptions to this--the times when
 485          two narrow values can be combined in their narrow type even to
 486          make a wider result--are handled by "shorten" in build_binary_op.  */
 487
 488       switch (ex_form)
 489         {
 490         case RSHIFT_EXPR:
 491           /* We can pass truncation down through right shifting
 492              when the shift count is a nonpositive constant.  */
 493           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 494               && tree_int_cst_lt (TREE_OPERAND (expr, 1),
 495                                   convert (TREE_TYPE (TREE_OPERAND (expr, 1)),
 496                                            integer_one_node)))
 497             goto trunc1;
 498           break;
 499
 500         case LSHIFT_EXPR:
 501           /* We can pass truncation down through left shifting
 502              when the shift count is a nonnegative constant and
 503              the target type is unsigned.  */
 504           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 505               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 506               && TYPE_UNSIGNED (type)
 507               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 508             {
 509               /* If shift count is less than the width of the truncated type,
 510                  really shift.  */
 511               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 512                 /* In this case, shifting is like multiplication.  */
 513                 goto trunc1;
 514               else
 515                 {
 516                   /* If it is >= that width, result is zero.
 517                      Handling this with trunc1 would give the wrong result:
 518                      (int) ((long long) a << 32) is well defined (as 0)
 519                      but (int) a << 32 is undefined and would get a
 520                      warning.  */
 521
 522                   tree t = convert_to_integer (type, integer_zero_node);
 523
 524                   /* If the original expression had side-effects, we must
 525                      preserve it.  */
 526                   if (TREE_SIDE_EFFECTS (expr))
 527                     return build (COMPOUND_EXPR, type, expr, t);
 528                   else
 529                     return t;
 530                 }
 531             }
 532           break;
 533
 534         case MAX_EXPR:
 535         case MIN_EXPR:
 536         case MULT_EXPR:
 537           {
 538             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 539             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 540
 541             /* Don't distribute unless the output precision is at least as big
 542                as the actual inputs.  Otherwise, the comparison of the
 543                truncated values will be wrong.  */
 544             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 545                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 546                 /* If signedness of arg0 and arg1 don't match,
 547                    we can't necessarily find a type to compare them in.  */
 548                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 549                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 550               goto trunc1;
 551             break;
 552           }
 553
 554         case PLUS_EXPR:
 555         case MINUS_EXPR:
 556         case BIT_AND_EXPR:
 557         case BIT_IOR_EXPR:
 558         case BIT_XOR_EXPR:
 559         trunc1:
 560           {
 561             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 562             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 563
 564             if (outprec >= BITS_PER_WORD
 565                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 566                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 567                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 568               {
 569                 /* Do the arithmetic in type TYPEX,
 570                    then convert result to TYPE.  */
 571                 tree typex = type;
 572
 573                 /* Can't do arithmetic in enumeral types
 574                    so use an integer type that will hold the values.  */
 575                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 576                   typex = lang_hooks.types.type_for_size
 577                     (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 578
 579                 /* But now perhaps TYPEX is as wide as INPREC.
 580                    In that case, do nothing special here.
 581                    (Otherwise would recurse infinitely in convert.  */
 582                 if (TYPE_PRECISION (typex) != inprec)
 583                   {
 584                     /* Don't do unsigned arithmetic where signed was wanted,
 585                        or vice versa.
 586                        Exception: if both of the original operands were
 587                        unsigned then we can safely do the work as unsigned.
 588                        Exception: shift operations take their type solely
 589                        from the first argument.
 590                        Exception: the LSHIFT_EXPR case above requires that
 591                        we perform this operation unsigned lest we produce
 592                        signed-overflow undefinedness.
 593                        And we may need to do it as unsigned
 594                        if we truncate to the original size.  */
 595                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 596                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 597                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 598                                 || ex_form == LSHIFT_EXPR
 599                                 || ex_form == RSHIFT_EXPR
 600                                 || ex_form == LROTATE_EXPR
 601                                 || ex_form == RROTATE_EXPR))
 602                         || ex_form == LSHIFT_EXPR)
 603                       typex = lang_hooks.types.unsigned_type (typex);
 604                     else
 605                       typex = lang_hooks.types.signed_type (typex);
 606                     return convert (type,
 607                                     fold (build (ex_form, typex,
 608                                                  convert (typex, arg0),
 609                                                  convert (typex, arg1))));
 610                   }
 611               }
 612           }
 613           break;
 614
 615         case NEGATE_EXPR:
 616         case BIT_NOT_EXPR:
 617           /* This is not correct for ABS_EXPR,
 618              since we must test the sign before truncation.  */
 619           {
 620             tree typex = type;
 621
 622             /* Can't do arithmetic in enumeral types
 623                so use an integer type that will hold the values.  */
 624             if (TREE_CODE (typex) == ENUMERAL_TYPE)
 625               typex = lang_hooks.types.type_for_size
 626                 (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 627
 628             /* But now perhaps TYPEX is as wide as INPREC.
 629                In that case, do nothing special here.
 630                (Otherwise would recurse infinitely in convert.  */
 631             if (TYPE_PRECISION (typex) != inprec)
 632               {
 633                 /* Don't do unsigned arithmetic where signed was wanted,
 634                    or vice versa.  */
 635                 if (TYPE_UNSIGNED (TREE_TYPE (expr)))
 636                   typex = lang_hooks.types.unsigned_type (typex);
 637                 else
 638                   typex = lang_hooks.types.signed_type (typex);
 639                 return convert (type,
 640                                 fold (build1 (ex_form, typex,
 641                                               convert (typex,
 642                                                        TREE_OPERAND (expr, 0)))));
 643               }
 644           }
 645
 646         case NOP_EXPR:
 647           /* Don't introduce a
 648              "can't convert between vector values of different size" error.  */
 649           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 650               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 651                   != GET_MODE_SIZE (TYPE_MODE (type))))
 652             break;
 653           /* If truncating after truncating, might as well do all at once.
 654              If truncating after extending, we may get rid of wasted work.  */
 655           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 656
 657         case COND_EXPR:
 658           /* It is sometimes worthwhile to push the narrowing down through
 659              the conditional and never loses.  */
 660           return fold (build (COND_EXPR, type, TREE_OPERAND (expr, 0),
 661                               convert (type, TREE_OPERAND (expr, 1)),
 662                               convert (type, TREE_OPERAND (expr, 2))));
 663
 664         default:
 665           break;
 666         }
 667
 668       return build1 (CONVERT_EXPR, type, expr);
 669
 670     case REAL_TYPE:
 671       return build1 (FIX_TRUNC_EXPR, type, expr);
 672
 673     case COMPLEX_TYPE:
 674       return convert (type,
 675                       fold (build1 (REALPART_EXPR,
 676                                     TREE_TYPE (TREE_TYPE (expr)), expr)));
 677
 678     case VECTOR_TYPE:
 679       if (GET_MODE_SIZE (TYPE_MODE (type))
 680           != GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))))
 681         {
 682           error ("can't convert between vector values of different size");
 683           return error_mark_node;
 684         }
 685       return build1 (NOP_EXPR, type, expr);
 686
 687     default:
 688       error ("aggregate value used where an integer was expected");
 689       return convert (type, integer_zero_node);
 690     }
 691 }
 692
 693 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 694
 695 tree
 696 convert_to_complex (tree type, tree expr)
 697 {
 698   tree subtype = TREE_TYPE (type);
 699
 700   switch (TREE_CODE (TREE_TYPE (expr)))
 701     {
 702     case REAL_TYPE:
 703     case INTEGER_TYPE:
 704     case ENUMERAL_TYPE:
 705     case BOOLEAN_TYPE:
 706     case CHAR_TYPE:
 707       return build (COMPLEX_EXPR, type, convert (subtype, expr),
 708                     convert (subtype, integer_zero_node));
 709
 710     case COMPLEX_TYPE:
 711       {
 712         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 713
 714         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 715           return expr;
 716         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 717           return fold (build (COMPLEX_EXPR,
 718                               type,
 719                               convert (subtype, TREE_OPERAND (expr, 0)),
 720                               convert (subtype, TREE_OPERAND (expr, 1))));
 721         else
 722           {
 723             expr = save_expr (expr);
 724             return
 725               fold (build (COMPLEX_EXPR,
 726                            type, convert (subtype,
 727                                           fold (build1 (REALPART_EXPR,
 728                                                         TREE_TYPE (TREE_TYPE (expr)),
 729                                                         expr))),
 730                            convert (subtype,
 731                                     fold (build1 (IMAGPART_EXPR,
 732                                                   TREE_TYPE (TREE_TYPE (expr)),
 733                                                   expr)))));
 734           }
 735       }
 736
 737     case POINTER_TYPE:
 738     case REFERENCE_TYPE:
 739       error ("pointer value used where a complex was expected");
 740       return convert_to_complex (type, integer_zero_node);
 741
 742     default:
 743       error ("aggregate value used where a complex was expected");
 744       return convert_to_complex (type, integer_zero_node);
 745     }
 746 }
 747
 748 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 749
 750 tree
 751 convert_to_vector (tree type, tree expr)
 752 {
 753   switch (TREE_CODE (TREE_TYPE (expr)))
 754     {
 755     case INTEGER_TYPE:
 756     case VECTOR_TYPE:
 757       if (GET_MODE_SIZE (TYPE_MODE (type))
 758           != GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))))
 759         {
 760           error ("can't convert between vector values of different size");
 761           return error_mark_node;
 762         }
 763       return build1 (NOP_EXPR, type, expr);
 764
 765     default:
 766       error ("can't convert value to a vector");
 767       return convert_to_vector (type, integer_zero_node);
 768     }
 769 }