gcc/convert.c

   1 /* Utility routines for data type conversion for GCC.
   2    Copyright (C) 1987-2013 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20
  21 /* These routines are somewhat language-independent utility function
  22    intended to be called by the language-specific convert () functions.  */
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "coretypes.h"
  27 #include "tm.h"
  28 #include "tree.h"
  29 #include "flags.h"
  30 #include "convert.h"
  31 #include "diagnostic-core.h"
  32 #include "langhooks.h"
  33
  34 /* Convert EXPR to some pointer or reference type TYPE.
  35    EXPR must be pointer, reference, integer, enumeral, or literal zero;
  36    in other cases error is called.  */
  37
  38 tree
  39 convert_to_pointer (tree type, tree expr)
  40 {
  41   location_t loc = EXPR_LOCATION (expr);
  42   if (TREE_TYPE (expr) == type)
  43     return expr;
  44
  45   switch (TREE_CODE (TREE_TYPE (expr)))
  46     {
  47     case POINTER_TYPE:
  48     case REFERENCE_TYPE:
  49       {
  50         /* If the pointers point to different address spaces, conversion needs
  51            to be done via a ADDR_SPACE_CONVERT_EXPR instead of a NOP_EXPR.  */
  52         addr_space_t to_as = TYPE_ADDR_SPACE (TREE_TYPE (type));
  53         addr_space_t from_as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (expr)));
  54
  55         if (to_as == from_as)
  56           return fold_build1_loc (loc, NOP_EXPR, type, expr);
  57         else
  58           return fold_build1_loc (loc, ADDR_SPACE_CONVERT_EXPR, type, expr);
  59       }
  60
  61     case INTEGER_TYPE:
  62     case ENUMERAL_TYPE:
  63     case BOOLEAN_TYPE:
  64       {
  65         /* If the input precision differs from the target pointer type
  66            precision, first convert the input expression to an integer type of
  67            the target precision.  Some targets, e.g. VMS, need several pointer
  68            sizes to coexist so the latter isn't necessarily POINTER_SIZE.  */
  69         unsigned int pprec = TYPE_PRECISION (type);
  70         unsigned int eprec = TYPE_PRECISION (TREE_TYPE (expr));
  71
  72         if (eprec != pprec)
  73           expr = fold_build1_loc (loc, NOP_EXPR,
  74                               lang_hooks.types.type_for_size (pprec, 0),
  75                               expr);
  76       }
  77
  78       return fold_build1_loc (loc, CONVERT_EXPR, type, expr);
  79
  80     default:
  81       error ("cannot convert to a pointer type");
  82       return convert_to_pointer (type, integer_zero_node);
  83     }
  84 }
  85
  86
  87 /* Convert EXPR to some floating-point type TYPE.
  88
  89    EXPR must be float, fixed-point, integer, or enumeral;
  90    in other cases error is called.  */
  91
  92 tree
  93 convert_to_real (tree type, tree expr)
  94 {
  95   enum built_in_function fcode = builtin_mathfn_code (expr);
  96   tree itype = TREE_TYPE (expr);
  97
  98   /* Disable until we figure out how to decide whether the functions are
  99      present in runtime.  */
 100   /* Convert (float)sqrt((double)x) where x is float into sqrtf(x) */
 101   if (optimize
 102       && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 103           || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 104     {
 105       switch (fcode)
 106         {
 107 #define CASE_MATHFN(FN) case BUILT_IN_##FN: case BUILT_IN_##FN##L:
 108           CASE_MATHFN (COSH)
 109           CASE_MATHFN (EXP)
 110           CASE_MATHFN (EXP10)
 111           CASE_MATHFN (EXP2)
 112           CASE_MATHFN (EXPM1)
 113           CASE_MATHFN (GAMMA)
 114           CASE_MATHFN (J0)
 115           CASE_MATHFN (J1)
 116           CASE_MATHFN (LGAMMA)
 117           CASE_MATHFN (POW10)
 118           CASE_MATHFN (SINH)
 119           CASE_MATHFN (TGAMMA)
 120           CASE_MATHFN (Y0)
 121           CASE_MATHFN (Y1)
 122             /* The above functions may set errno differently with float
 123                input or output so this transformation is not safe with
 124                -fmath-errno.  */
 125             if (flag_errno_math)
 126               break;
 127           CASE_MATHFN (ACOS)
 128           CASE_MATHFN (ACOSH)
 129           CASE_MATHFN (ASIN)
 130           CASE_MATHFN (ASINH)
 131           CASE_MATHFN (ATAN)
 132           CASE_MATHFN (ATANH)
 133           CASE_MATHFN (CBRT)
 134           CASE_MATHFN (COS)
 135           CASE_MATHFN (ERF)
 136           CASE_MATHFN (ERFC)
 137           CASE_MATHFN (FABS)
 138           CASE_MATHFN (LOG)
 139           CASE_MATHFN (LOG10)
 140           CASE_MATHFN (LOG2)
 141           CASE_MATHFN (LOG1P)
 142           CASE_MATHFN (LOGB)
 143           CASE_MATHFN (SIN)
 144           CASE_MATHFN (SQRT)
 145           CASE_MATHFN (TAN)
 146           CASE_MATHFN (TANH)
 147 #undef CASE_MATHFN
 148             {
 149               tree arg0 = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 150               tree newtype = type;
 151
 152               /* We have (outertype)sqrt((innertype)x).  Choose the wider mode from
 153                  the both as the safe type for operation.  */
 154               if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (type))
 155                 newtype = TREE_TYPE (arg0);
 156
 157               /* Be careful about integer to fp conversions.
 158                  These may overflow still.  */
 159               if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 160                   && TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 161                   && (TYPE_MODE (newtype) == TYPE_MODE (double_type_node)
 162                       || TYPE_MODE (newtype) == TYPE_MODE (float_type_node)))
 163                 {
 164                   tree fn = mathfn_built_in (newtype, fcode);
 165
 166                   if (fn)
 167                   {
 168                     tree arg = fold (convert_to_real (newtype, arg0));
 169                     expr = build_call_expr (fn, 1, arg);
 170                     if (newtype == type)
 171                       return expr;
 172                   }
 173                 }
 174             }
 175         default:
 176           break;
 177         }
 178     }
 179   if (optimize
 180       && (((fcode == BUILT_IN_FLOORL
 181            || fcode == BUILT_IN_CEILL
 182            || fcode == BUILT_IN_ROUNDL
 183            || fcode == BUILT_IN_RINTL
 184            || fcode == BUILT_IN_TRUNCL
 185            || fcode == BUILT_IN_NEARBYINTL)
 186           && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 187               || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 188           || ((fcode == BUILT_IN_FLOOR
 189                || fcode == BUILT_IN_CEIL
 190                || fcode == BUILT_IN_ROUND
 191                || fcode == BUILT_IN_RINT
 192                || fcode == BUILT_IN_TRUNC
 193                || fcode == BUILT_IN_NEARBYINT)
 194               && (TYPE_MODE (type) == TYPE_MODE (float_type_node)))))
 195     {
 196       tree fn = mathfn_built_in (type, fcode);
 197
 198       if (fn)
 199         {
 200           tree arg = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 201
 202           /* Make sure (type)arg0 is an extension, otherwise we could end up
 203              changing (float)floor(double d) into floorf((float)d), which is
 204              incorrect because (float)d uses round-to-nearest and can round
 205              up to the next integer.  */
 206           if (TYPE_PRECISION (type) >= TYPE_PRECISION (TREE_TYPE (arg)))
 207             return build_call_expr (fn, 1, fold (convert_to_real (type, arg)));
 208         }
 209     }
 210
 211   /* Propagate the cast into the operation.  */
 212   if (itype != type && FLOAT_TYPE_P (type))
 213     switch (TREE_CODE (expr))
 214       {
 215         /* Convert (float)-x into -(float)x.  This is safe for
 216            round-to-nearest rounding mode when the inner type is float.  */
 217         case ABS_EXPR:
 218         case NEGATE_EXPR:
 219           if (!flag_rounding_math
 220               && FLOAT_TYPE_P (itype)
 221               && TYPE_PRECISION (type) < TYPE_PRECISION (itype))
 222             return build1 (TREE_CODE (expr), type,
 223                            fold (convert_to_real (type,
 224                                                   TREE_OPERAND (expr, 0))));
 225           break;
 226         /* Convert (outertype)((innertype0)a+(innertype1)b)
 227            into ((newtype)a+(newtype)b) where newtype
 228            is the widest mode from all of these.  */
 229         case PLUS_EXPR:
 230         case MINUS_EXPR:
 231         case MULT_EXPR:
 232         case RDIV_EXPR:
 233            {
 234              tree arg0 = strip_float_extensions (TREE_OPERAND (expr, 0));
 235              tree arg1 = strip_float_extensions (TREE_OPERAND (expr, 1));
 236
 237              if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 238                  && FLOAT_TYPE_P (TREE_TYPE (arg1))
 239                  && DECIMAL_FLOAT_TYPE_P (itype) == DECIMAL_FLOAT_TYPE_P (type))
 240                {
 241                   tree newtype = type;
 242
 243                   if (TYPE_MODE (TREE_TYPE (arg0)) == SDmode
 244                       || TYPE_MODE (TREE_TYPE (arg1)) == SDmode
 245                       || TYPE_MODE (type) == SDmode)
 246                     newtype = dfloat32_type_node;
 247                   if (TYPE_MODE (TREE_TYPE (arg0)) == DDmode
 248                       || TYPE_MODE (TREE_TYPE (arg1)) == DDmode
 249                       || TYPE_MODE (type) == DDmode)
 250                     newtype = dfloat64_type_node;
 251                   if (TYPE_MODE (TREE_TYPE (arg0)) == TDmode
 252                       || TYPE_MODE (TREE_TYPE (arg1)) == TDmode
 253                       || TYPE_MODE (type) == TDmode)
 254                     newtype = dfloat128_type_node;
 255                   if (newtype == dfloat32_type_node
 256                       || newtype == dfloat64_type_node
 257                       || newtype == dfloat128_type_node)
 258                     {
 259                       expr = build2 (TREE_CODE (expr), newtype,
 260                                      fold (convert_to_real (newtype, arg0)),
 261                                      fold (convert_to_real (newtype, arg1)));
 262                       if (newtype == type)
 263                         return expr;
 264                       break;
 265                     }
 266
 267                   if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (newtype))
 268                     newtype = TREE_TYPE (arg0);
 269                   if (TYPE_PRECISION (TREE_TYPE (arg1)) > TYPE_PRECISION (newtype))
 270                     newtype = TREE_TYPE (arg1);
 271                   /* Sometimes this transformation is safe (cannot
 272                      change results through affecting double rounding
 273                      cases) and sometimes it is not.  If NEWTYPE is
 274                      wider than TYPE, e.g. (float)((long double)double
 275                      + (long double)double) converted to
 276                      (float)(double + double), the transformation is
 277                      unsafe regardless of the details of the types
 278                      involved; double rounding can arise if the result
 279                      of NEWTYPE arithmetic is a NEWTYPE value half way
 280                      between two representable TYPE values but the
 281                      exact value is sufficiently different (in the
 282                      right direction) for this difference to be
 283                      visible in ITYPE arithmetic.  If NEWTYPE is the
 284                      same as TYPE, however, the transformation may be
 285                      safe depending on the types involved: it is safe
 286                      if the ITYPE has strictly more than twice as many
 287                      mantissa bits as TYPE, can represent infinities
 288                      and NaNs if the TYPE can, and has sufficient
 289                      exponent range for the product or ratio of two
 290                      values representable in the TYPE to be within the
 291                      range of normal values of ITYPE.  */
 292                   if (TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 293                       && (flag_unsafe_math_optimizations
 294                           || (TYPE_PRECISION (newtype) == TYPE_PRECISION (type)
 295                               && real_can_shorten_arithmetic (TYPE_MODE (itype),
 296                                                               TYPE_MODE (type))
 297                               && !excess_precision_type (newtype))))
 298                     {
 299                       expr = build2 (TREE_CODE (expr), newtype,
 300                                      fold (convert_to_real (newtype, arg0)),
 301                                      fold (convert_to_real (newtype, arg1)));
 302                       if (newtype == type)
 303                         return expr;
 304                     }
 305                }
 306            }
 307           break;
 308         default:
 309           break;
 310       }
 311
 312   switch (TREE_CODE (TREE_TYPE (expr)))
 313     {
 314     case REAL_TYPE:
 315       /* Ignore the conversion if we don't need to store intermediate
 316          results and neither type is a decimal float.  */
 317       return build1 ((flag_float_store
 318                      || DECIMAL_FLOAT_TYPE_P (type)
 319                      || DECIMAL_FLOAT_TYPE_P (itype))
 320                      ? CONVERT_EXPR : NOP_EXPR, type, expr);
 321
 322     case INTEGER_TYPE:
 323     case ENUMERAL_TYPE:
 324     case BOOLEAN_TYPE:
 325       return build1 (FLOAT_EXPR, type, expr);
 326
 327     case FIXED_POINT_TYPE:
 328       return build1 (FIXED_CONVERT_EXPR, type, expr);
 329
 330     case COMPLEX_TYPE:
 331       return convert (type,
 332                       fold_build1 (REALPART_EXPR,
 333                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 334
 335     case POINTER_TYPE:
 336     case REFERENCE_TYPE:
 337       error ("pointer value used where a floating point value was expected");
 338       return convert_to_real (type, integer_zero_node);
 339
 340     default:
 341       error ("aggregate value used where a float was expected");
 342       return convert_to_real (type, integer_zero_node);
 343     }
 344 }
 345
 346 /* Convert EXPR to some integer (or enum) type TYPE.
 347
 348    EXPR must be pointer, integer, discrete (enum, char, or bool), float,
 349    fixed-point or vector; in other cases error is called.
 350
 351    The result of this is always supposed to be a newly created tree node
 352    not in use in any existing structure.  */
 353
 354 tree
 355 convert_to_integer (tree type, tree expr)
 356 {
 357   enum tree_code ex_form = TREE_CODE (expr);
 358   tree intype = TREE_TYPE (expr);
 359   unsigned int inprec = element_precision (intype);
 360   unsigned int outprec = element_precision (type);
 361
 362   /* An INTEGER_TYPE cannot be incomplete, but an ENUMERAL_TYPE can
 363      be.  Consider `enum E = { a, b = (enum E) 3 };'.  */
 364   if (!COMPLETE_TYPE_P (type))
 365     {
 366       error ("conversion to incomplete type");
 367       return error_mark_node;
 368     }
 369
 370   /* Convert e.g. (long)round(d) -> lround(d).  */
 371   /* If we're converting to char, we may encounter differing behavior
 372      between converting from double->char vs double->long->char.
 373      We're in "undefined" territory but we prefer to be conservative,
 374      so only proceed in "unsafe" math mode.  */
 375   if (optimize
 376       && (flag_unsafe_math_optimizations
 377           || (long_integer_type_node
 378               && outprec >= TYPE_PRECISION (long_integer_type_node))))
 379     {
 380       tree s_expr = strip_float_extensions (expr);
 381       tree s_intype = TREE_TYPE (s_expr);
 382       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 383       tree fn = 0;
 384
 385       switch (fcode)
 386         {
 387         CASE_FLT_FN (BUILT_IN_CEIL):
 388           /* Only convert in ISO C99 mode.  */
 389           if (!TARGET_C99_FUNCTIONS)
 390             break;
 391           if (outprec < TYPE_PRECISION (integer_type_node)
 392               || (outprec == TYPE_PRECISION (integer_type_node)
 393                   && !TYPE_UNSIGNED (type)))
 394             fn = mathfn_built_in (s_intype, BUILT_IN_ICEIL);
 395           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 396                    && !TYPE_UNSIGNED (type))
 397             fn = mathfn_built_in (s_intype, BUILT_IN_LCEIL);
 398           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 399                    && !TYPE_UNSIGNED (type))
 400             fn = mathfn_built_in (s_intype, BUILT_IN_LLCEIL);
 401           break;
 402
 403         CASE_FLT_FN (BUILT_IN_FLOOR):
 404           /* Only convert in ISO C99 mode.  */
 405           if (!TARGET_C99_FUNCTIONS)
 406             break;
 407           if (outprec < TYPE_PRECISION (integer_type_node)
 408               || (outprec == TYPE_PRECISION (integer_type_node)
 409                   && !TYPE_UNSIGNED (type)))
 410             fn = mathfn_built_in (s_intype, BUILT_IN_IFLOOR);
 411           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 412                    && !TYPE_UNSIGNED (type))
 413             fn = mathfn_built_in (s_intype, BUILT_IN_LFLOOR);
 414           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 415                    && !TYPE_UNSIGNED (type))
 416             fn = mathfn_built_in (s_intype, BUILT_IN_LLFLOOR);
 417           break;
 418
 419         CASE_FLT_FN (BUILT_IN_ROUND):
 420           /* Only convert in ISO C99 mode.  */
 421           if (!TARGET_C99_FUNCTIONS)
 422             break;
 423           if (outprec < TYPE_PRECISION (integer_type_node)
 424               || (outprec == TYPE_PRECISION (integer_type_node)
 425                   && !TYPE_UNSIGNED (type)))
 426             fn = mathfn_built_in (s_intype, BUILT_IN_IROUND);
 427           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 428                    && !TYPE_UNSIGNED (type))
 429             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 430           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 431                    && !TYPE_UNSIGNED (type))
 432             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 433           break;
 434
 435         CASE_FLT_FN (BUILT_IN_NEARBYINT):
 436           /* Only convert nearbyint* if we can ignore math exceptions.  */
 437           if (flag_trapping_math)
 438             break;
 439           /* ... Fall through ...  */
 440         CASE_FLT_FN (BUILT_IN_RINT):
 441           /* Only convert in ISO C99 mode.  */
 442           if (!TARGET_C99_FUNCTIONS)
 443             break;
 444           if (outprec < TYPE_PRECISION (integer_type_node)
 445               || (outprec == TYPE_PRECISION (integer_type_node)
 446                   && !TYPE_UNSIGNED (type)))
 447             fn = mathfn_built_in (s_intype, BUILT_IN_IRINT);
 448           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 449                    && !TYPE_UNSIGNED (type))
 450             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 451           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 452                    && !TYPE_UNSIGNED (type))
 453             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 454           break;
 455
 456         CASE_FLT_FN (BUILT_IN_TRUNC):
 457           return convert_to_integer (type, CALL_EXPR_ARG (s_expr, 0));
 458
 459         default:
 460           break;
 461         }
 462
 463       if (fn)
 464         {
 465           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 466           return convert_to_integer (type, newexpr);
 467         }
 468     }
 469
 470   /* Convert (int)logb(d) -> ilogb(d).  */
 471   if (optimize
 472       && flag_unsafe_math_optimizations
 473       && !flag_trapping_math && !flag_errno_math && flag_finite_math_only
 474       && integer_type_node
 475       && (outprec > TYPE_PRECISION (integer_type_node)
 476           || (outprec == TYPE_PRECISION (integer_type_node)
 477               && !TYPE_UNSIGNED (type))))
 478     {
 479       tree s_expr = strip_float_extensions (expr);
 480       tree s_intype = TREE_TYPE (s_expr);
 481       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 482       tree fn = 0;
 483
 484       switch (fcode)
 485         {
 486         CASE_FLT_FN (BUILT_IN_LOGB):
 487           fn = mathfn_built_in (s_intype, BUILT_IN_ILOGB);
 488           break;
 489
 490         default:
 491           break;
 492         }
 493
 494       if (fn)
 495         {
 496           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 497           return convert_to_integer (type, newexpr);
 498         }
 499     }
 500
 501   switch (TREE_CODE (intype))
 502     {
 503     case POINTER_TYPE:
 504     case REFERENCE_TYPE:
 505       if (integer_zerop (expr))
 506         return build_int_cst (type, 0);
 507
 508       /* Convert to an unsigned integer of the correct width first, and from
 509          there widen/truncate to the required type.  Some targets support the
 510          coexistence of multiple valid pointer sizes, so fetch the one we need
 511          from the type.  */
 512       expr = fold_build1 (CONVERT_EXPR,
 513                           lang_hooks.types.type_for_size
 514                             (TYPE_PRECISION (intype), 0),
 515                           expr);
 516       return fold_convert (type, expr);
 517
 518     case INTEGER_TYPE:
 519     case ENUMERAL_TYPE:
 520     case BOOLEAN_TYPE:
 521     case OFFSET_TYPE:
 522       /* If this is a logical operation, which just returns 0 or 1, we can
 523          change the type of the expression.  */
 524
 525       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 526         {
 527           expr = copy_node (expr);
 528           TREE_TYPE (expr) = type;
 529           return expr;
 530         }
 531
 532       /* If we are widening the type, put in an explicit conversion.
 533          Similarly if we are not changing the width.  After this, we know
 534          we are truncating EXPR.  */
 535
 536       else if (outprec >= inprec)
 537         {
 538           enum tree_code code;
 539
 540           /* If the precision of the EXPR's type is K bits and the
 541              destination mode has more bits, and the sign is changing,
 542              it is not safe to use a NOP_EXPR.  For example, suppose
 543              that EXPR's type is a 3-bit unsigned integer type, the
 544              TYPE is a 3-bit signed integer type, and the machine mode
 545              for the types is 8-bit QImode.  In that case, the
 546              conversion necessitates an explicit sign-extension.  In
 547              the signed-to-unsigned case the high-order bits have to
 548              be cleared.  */
 549           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 550               && (TYPE_PRECISION (TREE_TYPE (expr))
 551                   != GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (expr)))))
 552             code = CONVERT_EXPR;
 553           else
 554             code = NOP_EXPR;
 555
 556           return fold_build1 (code, type, expr);
 557         }
 558
 559       /* If TYPE is an enumeral type or a type with a precision less
 560          than the number of bits in its mode, do the conversion to the
 561          type corresponding to its mode, then do a nop conversion
 562          to TYPE.  */
 563       else if (TREE_CODE (type) == ENUMERAL_TYPE
 564                || outprec != GET_MODE_PRECISION (TYPE_MODE (type)))
 565         return build1 (NOP_EXPR, type,
 566                        convert (lang_hooks.types.type_for_mode
 567                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 568                                 expr));
 569
 570       /* Here detect when we can distribute the truncation down past some
 571          arithmetic.  For example, if adding two longs and converting to an
 572          int, we can equally well convert both to ints and then add.
 573          For the operations handled here, such truncation distribution
 574          is always safe.
 575          It is desirable in these cases:
 576          1) when truncating down to full-word from a larger size
 577          2) when truncating takes no work.
 578          3) when at least one operand of the arithmetic has been extended
 579          (as by C's default conversions).  In this case we need two conversions
 580          if we do the arithmetic as already requested, so we might as well
 581          truncate both and then combine.  Perhaps that way we need only one.
 582
 583          Note that in general we cannot do the arithmetic in a type
 584          shorter than the desired result of conversion, even if the operands
 585          are both extended from a shorter type, because they might overflow
 586          if combined in that type.  The exceptions to this--the times when
 587          two narrow values can be combined in their narrow type even to
 588          make a wider result--are handled by "shorten" in build_binary_op.  */
 589
 590       switch (ex_form)
 591         {
 592         case RSHIFT_EXPR:
 593           /* We can pass truncation down through right shifting
 594              when the shift count is a nonpositive constant.  */
 595           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 596               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) <= 0)
 597             goto trunc1;
 598           break;
 599
 600         case LSHIFT_EXPR:
 601           /* We can pass truncation down through left shifting
 602              when the shift count is a nonnegative constant and
 603              the target type is unsigned.  */
 604           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 605               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 606               && TYPE_UNSIGNED (type)
 607               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 608             {
 609               /* If shift count is less than the width of the truncated type,
 610                  really shift.  */
 611               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 612                 /* In this case, shifting is like multiplication.  */
 613                 goto trunc1;
 614               else
 615                 {
 616                   /* If it is >= that width, result is zero.
 617                      Handling this with trunc1 would give the wrong result:
 618                      (int) ((long long) a << 32) is well defined (as 0)
 619                      but (int) a << 32 is undefined and would get a
 620                      warning.  */
 621
 622                   tree t = build_int_cst (type, 0);
 623
 624                   /* If the original expression had side-effects, we must
 625                      preserve it.  */
 626                   if (TREE_SIDE_EFFECTS (expr))
 627                     return build2 (COMPOUND_EXPR, type, expr, t);
 628                   else
 629                     return t;
 630                 }
 631             }
 632           break;
 633
 634         case TRUNC_DIV_EXPR:
 635           {
 636             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 637             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 638
 639             /* Don't distribute unless the output precision is at least as big
 640                as the actual inputs and it has the same signedness.  */
 641             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 642                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 643                 /* If signedness of arg0 and arg1 don't match,
 644                    we can't necessarily find a type to compare them in.  */
 645                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 646                     == TYPE_UNSIGNED (TREE_TYPE (arg1)))
 647                 /* Do not change the sign of the division.  */
 648                 && (TYPE_UNSIGNED (TREE_TYPE (expr))
 649                     == TYPE_UNSIGNED (TREE_TYPE (arg0)))
 650                 /* Either require unsigned division or a division by
 651                    a constant that is not -1.  */
 652                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 653                     || (TREE_CODE (arg1) == INTEGER_CST
 654                         && !integer_all_onesp (arg1))))
 655               goto trunc1;
 656             break;
 657           }
 658
 659         case MAX_EXPR:
 660         case MIN_EXPR:
 661         case MULT_EXPR:
 662           {
 663             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 664             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 665
 666             /* Don't distribute unless the output precision is at least as big
 667                as the actual inputs.  Otherwise, the comparison of the
 668                truncated values will be wrong.  */
 669             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 670                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 671                 /* If signedness of arg0 and arg1 don't match,
 672                    we can't necessarily find a type to compare them in.  */
 673                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 674                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 675               goto trunc1;
 676             break;
 677           }
 678
 679         case PLUS_EXPR:
 680         case MINUS_EXPR:
 681         case BIT_AND_EXPR:
 682         case BIT_IOR_EXPR:
 683         case BIT_XOR_EXPR:
 684         trunc1:
 685           {
 686             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 687             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 688
 689             /* Do not try to narrow operands of pointer subtraction;
 690                that will interfere with other folding.  */
 691             if (ex_form == MINUS_EXPR
 692                 && CONVERT_EXPR_P (arg0)
 693                 && CONVERT_EXPR_P (arg1)
 694                 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 0)))
 695                 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0))))
 696               break;
 697
 698             if (outprec >= BITS_PER_WORD
 699                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 700                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 701                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 702               {
 703                 /* Do the arithmetic in type TYPEX,
 704                    then convert result to TYPE.  */
 705                 tree typex = type;
 706
 707                 /* Can't do arithmetic in enumeral types
 708                    so use an integer type that will hold the values.  */
 709                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 710                   typex = lang_hooks.types.type_for_size
 711                     (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 712
 713                 /* But now perhaps TYPEX is as wide as INPREC.
 714                    In that case, do nothing special here.
 715                    (Otherwise would recurse infinitely in convert.  */
 716                 if (TYPE_PRECISION (typex) != inprec)
 717                   {
 718                     /* Don't do unsigned arithmetic where signed was wanted,
 719                        or vice versa.
 720                        Exception: if both of the original operands were
 721                        unsigned then we can safely do the work as unsigned.
 722                        Exception: shift operations take their type solely
 723                        from the first argument.
 724                        Exception: the LSHIFT_EXPR case above requires that
 725                        we perform this operation unsigned lest we produce
 726                        signed-overflow undefinedness.
 727                        And we may need to do it as unsigned
 728                        if we truncate to the original size.  */
 729                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 730                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 731                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 732                                 || ex_form == LSHIFT_EXPR
 733                                 || ex_form == RSHIFT_EXPR
 734                                 || ex_form == LROTATE_EXPR
 735                                 || ex_form == RROTATE_EXPR))
 736                         || ex_form == LSHIFT_EXPR
 737                         /* If we have !flag_wrapv, and either ARG0 or
 738                            ARG1 is of a signed type, we have to do
 739                            PLUS_EXPR, MINUS_EXPR or MULT_EXPR in an unsigned
 740                            type in case the operation in outprec precision
 741                            could overflow.  Otherwise, we would introduce
 742                            signed-overflow undefinedness.  */
 743                         || ((!TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg0))
 744                              || !TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1)))
 745                             && ((TYPE_PRECISION (TREE_TYPE (arg0)) * 2u
 746                                  > outprec)
 747                                 || (TYPE_PRECISION (TREE_TYPE (arg1)) * 2u
 748                                     > outprec))
 749                             && (ex_form == PLUS_EXPR
 750                                 || ex_form == MINUS_EXPR
 751                                 || ex_form == MULT_EXPR)))
 752                       typex = unsigned_type_for (typex);
 753                     else
 754                       typex = signed_type_for (typex);
 755                     return convert (type,
 756                                     fold_build2 (ex_form, typex,
 757                                                  convert (typex, arg0),
 758                                                  convert (typex, arg1)));
 759                   }
 760               }
 761           }
 762           break;
 763
 764         case NEGATE_EXPR:
 765         case BIT_NOT_EXPR:
 766           /* This is not correct for ABS_EXPR,
 767              since we must test the sign before truncation.  */
 768           {
 769             tree typex = unsigned_type_for (type);
 770             return convert (type,
 771                             fold_build1 (ex_form, typex,
 772                                          convert (typex,
 773                                                   TREE_OPERAND (expr, 0))));
 774           }
 775
 776         case NOP_EXPR:
 777           /* Don't introduce a
 778              "can't convert between vector values of different size" error.  */
 779           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 780               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 781                   != GET_MODE_SIZE (TYPE_MODE (type))))
 782             break;
 783           /* If truncating after truncating, might as well do all at once.
 784              If truncating after extending, we may get rid of wasted work.  */
 785           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 786
 787         case COND_EXPR:
 788           /* It is sometimes worthwhile to push the narrowing down through
 789              the conditional and never loses.  A COND_EXPR may have a throw
 790              as one operand, which then has void type.  Just leave void
 791              operands as they are.  */
 792           return fold_build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 793                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 1)))
 794                               ? TREE_OPERAND (expr, 1)
 795                               : convert (type, TREE_OPERAND (expr, 1)),
 796                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 2)))
 797                               ? TREE_OPERAND (expr, 2)
 798                               : convert (type, TREE_OPERAND (expr, 2)));
 799
 800         default:
 801           break;
 802         }
 803
 804       /* When parsing long initializers, we might end up with a lot of casts.
 805          Shortcut this.  */
 806       if (TREE_CODE (expr) == INTEGER_CST)
 807         return fold_convert (type, expr);
 808       return build1 (CONVERT_EXPR, type, expr);
 809
 810     case REAL_TYPE:
 811       return build1 (FIX_TRUNC_EXPR, type, expr);
 812
 813     case FIXED_POINT_TYPE:
 814       return build1 (FIXED_CONVERT_EXPR, type, expr);
 815
 816     case COMPLEX_TYPE:
 817       return convert (type,
 818                       fold_build1 (REALPART_EXPR,
 819                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 820
 821     case VECTOR_TYPE:
 822       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 823         {
 824           error ("can%'t convert between vector values of different size");
 825           return error_mark_node;
 826         }
 827       return build1 (VIEW_CONVERT_EXPR, type, expr);
 828
 829     default:
 830       error ("aggregate value used where an integer was expected");
 831       return convert (type, integer_zero_node);
 832     }
 833 }
 834
 835 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 836
 837 tree
 838 convert_to_complex (tree type, tree expr)
 839 {
 840   tree subtype = TREE_TYPE (type);
 841
 842   switch (TREE_CODE (TREE_TYPE (expr)))
 843     {
 844     case REAL_TYPE:
 845     case FIXED_POINT_TYPE:
 846     case INTEGER_TYPE:
 847     case ENUMERAL_TYPE:
 848     case BOOLEAN_TYPE:
 849       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 850                      convert (subtype, integer_zero_node));
 851
 852     case COMPLEX_TYPE:
 853       {
 854         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 855
 856         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 857           return expr;
 858         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 859           return fold_build2 (COMPLEX_EXPR, type,
 860                               convert (subtype, TREE_OPERAND (expr, 0)),
 861                               convert (subtype, TREE_OPERAND (expr, 1)));
 862         else
 863           {
 864             expr = save_expr (expr);
 865             return
 866               fold_build2 (COMPLEX_EXPR, type,
 867                            convert (subtype,
 868                                     fold_build1 (REALPART_EXPR,
 869                                                  TREE_TYPE (TREE_TYPE (expr)),
 870                                                  expr)),
 871                            convert (subtype,
 872                                     fold_build1 (IMAGPART_EXPR,
 873                                                  TREE_TYPE (TREE_TYPE (expr)),
 874                                                  expr)));
 875           }
 876       }
 877
 878     case POINTER_TYPE:
 879     case REFERENCE_TYPE:
 880       error ("pointer value used where a complex was expected");
 881       return convert_to_complex (type, integer_zero_node);
 882
 883     default:
 884       error ("aggregate value used where a complex was expected");
 885       return convert_to_complex (type, integer_zero_node);
 886     }
 887 }
 888
 889 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 890
 891 tree
 892 convert_to_vector (tree type, tree expr)
 893 {
 894   switch (TREE_CODE (TREE_TYPE (expr)))
 895     {
 896     case INTEGER_TYPE:
 897     case VECTOR_TYPE:
 898       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 899         {
 900           error ("can%'t convert between vector values of different size");
 901           return error_mark_node;
 902         }
 903       return build1 (VIEW_CONVERT_EXPR, type, expr);
 904
 905     default:
 906       error ("can%'t convert value to a vector");
 907       return error_mark_node;
 908     }
 909 }
 910
 911 /* Convert EXPR to some fixed-point type TYPE.
 912
 913    EXPR must be fixed-point, float, integer, or enumeral;
 914    in other cases error is called.  */
 915
 916 tree
 917 convert_to_fixed (tree type, tree expr)
 918 {
 919   if (integer_zerop (expr))
 920     {
 921       tree fixed_zero_node = build_fixed (type, FCONST0 (TYPE_MODE (type)));
 922       return fixed_zero_node;
 923     }
 924   else if (integer_onep (expr) && ALL_SCALAR_ACCUM_MODE_P (TYPE_MODE (type)))
 925     {
 926       tree fixed_one_node = build_fixed (type, FCONST1 (TYPE_MODE (type)));
 927       return fixed_one_node;
 928     }
 929
 930   switch (TREE_CODE (TREE_TYPE (expr)))
 931     {
 932     case FIXED_POINT_TYPE:
 933     case INTEGER_TYPE:
 934     case ENUMERAL_TYPE:
 935     case BOOLEAN_TYPE:
 936     case REAL_TYPE:
 937       return build1 (FIXED_CONVERT_EXPR, type, expr);
 938
 939     case COMPLEX_TYPE:
 940       return convert (type,
 941                       fold_build1 (REALPART_EXPR,
 942                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 943
 944     default:
 945       error ("aggregate value used where a fixed-point was expected");
 946       return error_mark_node;
 947     }
 948 }