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_CEIL: case BUILT_IN_CEILF: case BUILT_IN_CEILL:
 353           /* Only convert in ISO C99 mode.  */
 354           if (!TARGET_C99_FUNCTIONS)
 355             break;
 356           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 357             fn = mathfn_built_in (s_intype, BUILT_IN_LLCEIL);
 358           else
 359             fn = mathfn_built_in (s_intype, BUILT_IN_LCEIL);
 360           break;
 361
 362         case BUILT_IN_FLOOR: case BUILT_IN_FLOORF: case BUILT_IN_FLOORL:
 363           /* Only convert in ISO C99 mode.  */
 364           if (!TARGET_C99_FUNCTIONS)
 365             break;
 366           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 367             fn = mathfn_built_in (s_intype, BUILT_IN_LLFLOOR);
 368           else
 369             fn = mathfn_built_in (s_intype, BUILT_IN_LFLOOR);
 370           break;
 371
 372         case BUILT_IN_ROUND: case BUILT_IN_ROUNDF: case BUILT_IN_ROUNDL:
 373           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 374             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 375           else
 376             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 377           break;
 378
 379         case BUILT_IN_RINT: case BUILT_IN_RINTF: case BUILT_IN_RINTL:
 380           /* Only convert rint* if we can ignore math exceptions.  */
 381           if (flag_trapping_math)
 382             break;
 383           /* ... Fall through ...  */
 384         case BUILT_IN_NEARBYINT: case BUILT_IN_NEARBYINTF: case BUILT_IN_NEARBYINTL:
 385           if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (long_long_integer_type_node))
 386             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 387           else
 388             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 389           break;
 390
 391         case BUILT_IN_TRUNC: case BUILT_IN_TRUNCF: case BUILT_IN_TRUNCL:
 392           {
 393             tree arglist = TREE_OPERAND (s_expr, 1);
 394             return convert_to_integer (type, TREE_VALUE (arglist));
 395           }
 396
 397         default:
 398           break;
 399         }
 400
 401       if (fn)
 402         {
 403           tree arglist = TREE_OPERAND (s_expr, 1);
 404           tree newexpr = build_function_call_expr (fn, arglist);
 405           return convert_to_integer (type, newexpr);
 406         }
 407     }
 408
 409   switch (TREE_CODE (intype))
 410     {
 411     case POINTER_TYPE:
 412     case REFERENCE_TYPE:
 413       if (integer_zerop (expr))
 414         expr = integer_zero_node;
 415       else
 416         expr = fold (build1 (CONVERT_EXPR,
 417                              lang_hooks.types.type_for_size (POINTER_SIZE, 0),
 418                              expr));
 419
 420       return convert_to_integer (type, expr);
 421
 422     case INTEGER_TYPE:
 423     case ENUMERAL_TYPE:
 424     case BOOLEAN_TYPE:
 425     case CHAR_TYPE:
 426       /* If this is a logical operation, which just returns 0 or 1, we can
 427          change the type of the expression.  */
 428
 429       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 430         {
 431           expr = copy_node (expr);
 432           TREE_TYPE (expr) = type;
 433           return expr;
 434         }
 435
 436       /* If we are widening the type, put in an explicit conversion.
 437          Similarly if we are not changing the width.  After this, we know
 438          we are truncating EXPR.  */
 439
 440       else if (outprec >= inprec)
 441         {
 442           enum tree_code code;
 443
 444           /* If the precision of the EXPR's type is K bits and the
 445              destination mode has more bits, and the sign is changing,
 446              it is not safe to use a NOP_EXPR.  For example, suppose
 447              that EXPR's type is a 3-bit unsigned integer type, the
 448              TYPE is a 3-bit signed integer type, and the machine mode
 449              for the types is 8-bit QImode.  In that case, the
 450              conversion necessitates an explicit sign-extension.  In
 451              the signed-to-unsigned case the high-order bits have to
 452              be cleared.  */
 453           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 454               && (TYPE_PRECISION (TREE_TYPE (expr))
 455                   != GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)))))
 456             code = CONVERT_EXPR;
 457           else
 458             code = NOP_EXPR;
 459
 460           return build1 (code, type, expr);
 461         }
 462
 463       /* If TYPE is an enumeral type or a type with a precision less
 464          than the number of bits in its mode, do the conversion to the
 465          type corresponding to its mode, then do a nop conversion
 466          to TYPE.  */
 467       else if (TREE_CODE (type) == ENUMERAL_TYPE
 468                || outprec != GET_MODE_BITSIZE (TYPE_MODE (type)))
 469         return build1 (NOP_EXPR, type,
 470                        convert (lang_hooks.types.type_for_mode
 471                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 472                                 expr));
 473
 474       /* Here detect when we can distribute the truncation down past some
 475          arithmetic.  For example, if adding two longs and converting to an
 476          int, we can equally well convert both to ints and then add.
 477          For the operations handled here, such truncation distribution
 478          is always safe.
 479          It is desirable in these cases:
 480          1) when truncating down to full-word from a larger size
 481          2) when truncating takes no work.
 482          3) when at least one operand of the arithmetic has been extended
 483          (as by C's default conversions).  In this case we need two conversions
 484          if we do the arithmetic as already requested, so we might as well
 485          truncate both and then combine.  Perhaps that way we need only one.
 486
 487          Note that in general we cannot do the arithmetic in a type
 488          shorter than the desired result of conversion, even if the operands
 489          are both extended from a shorter type, because they might overflow
 490          if combined in that type.  The exceptions to this--the times when
 491          two narrow values can be combined in their narrow type even to
 492          make a wider result--are handled by "shorten" in build_binary_op.  */
 493
 494       switch (ex_form)
 495         {
 496         case RSHIFT_EXPR:
 497           /* We can pass truncation down through right shifting
 498              when the shift count is a nonpositive constant.  */
 499           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 500               && tree_int_cst_lt (TREE_OPERAND (expr, 1),
 501                                   convert (TREE_TYPE (TREE_OPERAND (expr, 1)),
 502                                            integer_one_node)))
 503             goto trunc1;
 504           break;
 505
 506         case LSHIFT_EXPR:
 507           /* We can pass truncation down through left shifting
 508              when the shift count is a nonnegative constant and
 509              the target type is unsigned.  */
 510           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 511               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 512               && TYPE_UNSIGNED (type)
 513               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 514             {
 515               /* If shift count is less than the width of the truncated type,
 516                  really shift.  */
 517               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 518                 /* In this case, shifting is like multiplication.  */
 519                 goto trunc1;
 520               else
 521                 {
 522                   /* If it is >= that width, result is zero.
 523                      Handling this with trunc1 would give the wrong result:
 524                      (int) ((long long) a << 32) is well defined (as 0)
 525                      but (int) a << 32 is undefined and would get a
 526                      warning.  */
 527
 528                   tree t = convert_to_integer (type, integer_zero_node);
 529
 530                   /* If the original expression had side-effects, we must
 531                      preserve it.  */
 532                   if (TREE_SIDE_EFFECTS (expr))
 533                     return build2 (COMPOUND_EXPR, type, expr, t);
 534                   else
 535                     return t;
 536                 }
 537             }
 538           break;
 539
 540         case MAX_EXPR:
 541         case MIN_EXPR:
 542         case MULT_EXPR:
 543           {
 544             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 545             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 546
 547             /* Don't distribute unless the output precision is at least as big
 548                as the actual inputs.  Otherwise, the comparison of the
 549                truncated values will be wrong.  */
 550             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 551                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 552                 /* If signedness of arg0 and arg1 don't match,
 553                    we can't necessarily find a type to compare them in.  */
 554                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 555                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 556               goto trunc1;
 557             break;
 558           }
 559
 560         case PLUS_EXPR:
 561         case MINUS_EXPR:
 562         case BIT_AND_EXPR:
 563         case BIT_IOR_EXPR:
 564         case BIT_XOR_EXPR:
 565         trunc1:
 566           {
 567             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 568             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 569
 570             if (outprec >= BITS_PER_WORD
 571                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 572                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 573                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 574               {
 575                 /* Do the arithmetic in type TYPEX,
 576                    then convert result to TYPE.  */
 577                 tree typex = type;
 578
 579                 /* Can't do arithmetic in enumeral types
 580                    so use an integer type that will hold the values.  */
 581                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 582                   typex = lang_hooks.types.type_for_size
 583                     (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 584
 585                 /* But now perhaps TYPEX is as wide as INPREC.
 586                    In that case, do nothing special here.
 587                    (Otherwise would recurse infinitely in convert.  */
 588                 if (TYPE_PRECISION (typex) != inprec)
 589                   {
 590                     /* Don't do unsigned arithmetic where signed was wanted,
 591                        or vice versa.
 592                        Exception: if both of the original operands were
 593                        unsigned then we can safely do the work as unsigned.
 594                        Exception: shift operations take their type solely
 595                        from the first argument.
 596                        Exception: the LSHIFT_EXPR case above requires that
 597                        we perform this operation unsigned lest we produce
 598                        signed-overflow undefinedness.
 599                        And we may need to do it as unsigned
 600                        if we truncate to the original size.  */
 601                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 602                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 603                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 604                                 || ex_form == LSHIFT_EXPR
 605                                 || ex_form == RSHIFT_EXPR
 606                                 || ex_form == LROTATE_EXPR
 607                                 || ex_form == RROTATE_EXPR))
 608                         || ex_form == LSHIFT_EXPR)
 609                       typex = lang_hooks.types.unsigned_type (typex);
 610                     else
 611                       typex = lang_hooks.types.signed_type (typex);
 612                     return convert (type,
 613                                     fold (build2 (ex_form, typex,
 614                                                   convert (typex, arg0),
 615                                                   convert (typex, arg1))));
 616                   }
 617               }
 618           }
 619           break;
 620
 621         case NEGATE_EXPR:
 622         case BIT_NOT_EXPR:
 623           /* This is not correct for ABS_EXPR,
 624              since we must test the sign before truncation.  */
 625           {
 626             tree typex = type;
 627
 628             /* Can't do arithmetic in enumeral types
 629                so use an integer type that will hold the values.  */
 630             if (TREE_CODE (typex) == ENUMERAL_TYPE)
 631               typex = lang_hooks.types.type_for_size
 632                 (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 633
 634             /* But now perhaps TYPEX is as wide as INPREC.
 635                In that case, do nothing special here.
 636                (Otherwise would recurse infinitely in convert.  */
 637             if (TYPE_PRECISION (typex) != inprec)
 638               {
 639                 /* Don't do unsigned arithmetic where signed was wanted,
 640                    or vice versa.  */
 641                 if (TYPE_UNSIGNED (TREE_TYPE (expr)))
 642                   typex = lang_hooks.types.unsigned_type (typex);
 643                 else
 644                   typex = lang_hooks.types.signed_type (typex);
 645                 return convert (type,
 646                                 fold (build1 (ex_form, typex,
 647                                               convert (typex,
 648                                                        TREE_OPERAND (expr, 0)))));
 649               }
 650           }
 651
 652         case NOP_EXPR:
 653           /* Don't introduce a
 654              "can't convert between vector values of different size" error.  */
 655           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 656               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 657                   != GET_MODE_SIZE (TYPE_MODE (type))))
 658             break;
 659           /* If truncating after truncating, might as well do all at once.
 660              If truncating after extending, we may get rid of wasted work.  */
 661           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 662
 663         case COND_EXPR:
 664           /* It is sometimes worthwhile to push the narrowing down through
 665              the conditional and never loses.  */
 666           return fold (build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 667                                convert (type, TREE_OPERAND (expr, 1)),
 668                                convert (type, TREE_OPERAND (expr, 2))));
 669
 670         default:
 671           break;
 672         }
 673
 674       return build1 (CONVERT_EXPR, type, expr);
 675
 676     case REAL_TYPE:
 677       return build1 (FIX_TRUNC_EXPR, type, expr);
 678
 679     case COMPLEX_TYPE:
 680       return convert (type,
 681                       fold (build1 (REALPART_EXPR,
 682                                     TREE_TYPE (TREE_TYPE (expr)), expr)));
 683
 684     case VECTOR_TYPE:
 685       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 686         {
 687           error ("can't convert between vector values of different size");
 688           return error_mark_node;
 689         }
 690       return build1 (NOP_EXPR, type, expr);
 691
 692     default:
 693       error ("aggregate value used where an integer was expected");
 694       return convert (type, integer_zero_node);
 695     }
 696 }
 697
 698 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 699
 700 tree
 701 convert_to_complex (tree type, tree expr)
 702 {
 703   tree subtype = TREE_TYPE (type);
 704
 705   switch (TREE_CODE (TREE_TYPE (expr)))
 706     {
 707     case REAL_TYPE:
 708     case INTEGER_TYPE:
 709     case ENUMERAL_TYPE:
 710     case BOOLEAN_TYPE:
 711     case CHAR_TYPE:
 712       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 713                      convert (subtype, integer_zero_node));
 714
 715     case COMPLEX_TYPE:
 716       {
 717         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 718
 719         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 720           return expr;
 721         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 722           return fold (build2 (COMPLEX_EXPR, type,
 723                                convert (subtype, TREE_OPERAND (expr, 0)),
 724                                convert (subtype, TREE_OPERAND (expr, 1))));
 725         else
 726           {
 727             expr = save_expr (expr);
 728             return
 729               fold (build2 (COMPLEX_EXPR, type,
 730                             convert (subtype,
 731                                      fold (build1 (REALPART_EXPR,
 732                                                    TREE_TYPE (TREE_TYPE (expr)),
 733                                                    expr))),
 734                             convert (subtype,
 735                                      fold (build1 (IMAGPART_EXPR,
 736                                                    TREE_TYPE (TREE_TYPE (expr)),
 737                                                    expr)))));
 738           }
 739       }
 740
 741     case POINTER_TYPE:
 742     case REFERENCE_TYPE:
 743       error ("pointer value used where a complex was expected");
 744       return convert_to_complex (type, integer_zero_node);
 745
 746     default:
 747       error ("aggregate value used where a complex was expected");
 748       return convert_to_complex (type, integer_zero_node);
 749     }
 750 }
 751
 752 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 753
 754 tree
 755 convert_to_vector (tree type, tree expr)
 756 {
 757   switch (TREE_CODE (TREE_TYPE (expr)))
 758     {
 759     case INTEGER_TYPE:
 760     case VECTOR_TYPE:
 761       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 762         {
 763           error ("can't convert between vector values of different size");
 764           return error_mark_node;
 765         }
 766       return build1 (NOP_EXPR, type, expr);
 767
 768     default:
 769       error ("can't convert value to a vector");
 770       return error_mark_node;
 771     }
 772 }