gcc/convert.c

   1 /* Utility routines for data type conversion for GCC.
   2    Copyright (C) 1987, 1988, 1991, 1992, 1993, 1994, 1995, 1997, 1998,
   3    2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   4    Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  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 "diagnostic-core.h"
  34 #include "langhooks.h"
  35
  36 /* Convert EXPR to some pointer or reference type TYPE.
  37    EXPR must be pointer, reference, integer, enumeral, or literal zero;
  38    in other cases error is called.  */
  39
  40 tree
  41 convert_to_pointer (tree type, tree expr)
  42 {
  43   location_t loc = EXPR_LOCATION (expr);
  44   if (TREE_TYPE (expr) == type)
  45     return expr;
  46
  47   /* Propagate overflow to the NULL pointer.  */
  48   if (integer_zerop (expr))
  49     return force_fit_type_double (type, double_int_zero, 0,
  50                                   TREE_OVERFLOW (expr));
  51
  52   switch (TREE_CODE (TREE_TYPE (expr)))
  53     {
  54     case POINTER_TYPE:
  55     case REFERENCE_TYPE:
  56       {
  57         /* If the pointers point to different address spaces, conversion needs
  58            to be done via a ADDR_SPACE_CONVERT_EXPR instead of a NOP_EXPR.  */
  59         addr_space_t to_as = TYPE_ADDR_SPACE (TREE_TYPE (type));
  60         addr_space_t from_as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (expr)));
  61
  62         if (to_as == from_as)
  63           return fold_build1_loc (loc, NOP_EXPR, type, expr);
  64         else
  65           return fold_build1_loc (loc, ADDR_SPACE_CONVERT_EXPR, type, expr);
  66       }
  67
  68     case INTEGER_TYPE:
  69     case ENUMERAL_TYPE:
  70     case BOOLEAN_TYPE:
  71       {
  72         /* If the input precision differs from the target pointer type
  73            precision, first convert the input expression to an integer type of
  74            the target precision.  Some targets, e.g. VMS, need several pointer
  75            sizes to coexist so the latter isn't necessarily POINTER_SIZE.  */
  76         unsigned int pprec = TYPE_PRECISION (type);
  77         unsigned int eprec = TYPE_PRECISION (TREE_TYPE (expr));
  78
  79         if (eprec != pprec)
  80           expr = fold_build1_loc (loc, NOP_EXPR,
  81                               lang_hooks.types.type_for_size (pprec, 0),
  82                               expr);
  83       }
  84
  85       return fold_build1_loc (loc, CONVERT_EXPR, type, expr);
  86
  87     default:
  88       error ("cannot convert to a pointer type");
  89       return convert_to_pointer (type, integer_zero_node);
  90     }
  91 }
  92
  93 /* Avoid any floating point extensions from EXP.  */
  94 tree
  95 strip_float_extensions (tree exp)
  96 {
  97   tree sub, expt, subt;
  98
  99   /*  For floating point constant look up the narrowest type that can hold
 100       it properly and handle it like (type)(narrowest_type)constant.
 101       This way we can optimize for instance a=a*2.0 where "a" is float
 102       but 2.0 is double constant.  */
 103   if (TREE_CODE (exp) == REAL_CST && !DECIMAL_FLOAT_TYPE_P (TREE_TYPE (exp)))
 104     {
 105       REAL_VALUE_TYPE orig;
 106       tree type = NULL;
 107
 108       orig = TREE_REAL_CST (exp);
 109       if (TYPE_PRECISION (TREE_TYPE (exp)) > TYPE_PRECISION (float_type_node)
 110           && exact_real_truncate (TYPE_MODE (float_type_node), &orig))
 111         type = float_type_node;
 112       else if (TYPE_PRECISION (TREE_TYPE (exp))
 113                > TYPE_PRECISION (double_type_node)
 114                && exact_real_truncate (TYPE_MODE (double_type_node), &orig))
 115         type = double_type_node;
 116       if (type)
 117         return build_real (type, real_value_truncate (TYPE_MODE (type), orig));
 118     }
 119
 120   if (!CONVERT_EXPR_P (exp))
 121     return exp;
 122
 123   sub = TREE_OPERAND (exp, 0);
 124   subt = TREE_TYPE (sub);
 125   expt = TREE_TYPE (exp);
 126
 127   if (!FLOAT_TYPE_P (subt))
 128     return exp;
 129
 130   if (DECIMAL_FLOAT_TYPE_P (expt) != DECIMAL_FLOAT_TYPE_P (subt))
 131     return exp;
 132
 133   if (TYPE_PRECISION (subt) > TYPE_PRECISION (expt))
 134     return exp;
 135
 136   return strip_float_extensions (sub);
 137 }
 138
 139
 140 /* Convert EXPR to some floating-point type TYPE.
 141
 142    EXPR must be float, fixed-point, integer, or enumeral;
 143    in other cases error is called.  */
 144
 145 tree
 146 convert_to_real (tree type, tree expr)
 147 {
 148   enum built_in_function fcode = builtin_mathfn_code (expr);
 149   tree itype = TREE_TYPE (expr);
 150
 151   /* Disable until we figure out how to decide whether the functions are
 152      present in runtime.  */
 153   /* Convert (float)sqrt((double)x) where x is float into sqrtf(x) */
 154   if (optimize
 155       && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 156           || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 157     {
 158       switch (fcode)
 159         {
 160 #define CASE_MATHFN(FN) case BUILT_IN_##FN: case BUILT_IN_##FN##L:
 161           CASE_MATHFN (COSH)
 162           CASE_MATHFN (EXP)
 163           CASE_MATHFN (EXP10)
 164           CASE_MATHFN (EXP2)
 165           CASE_MATHFN (EXPM1)
 166           CASE_MATHFN (GAMMA)
 167           CASE_MATHFN (J0)
 168           CASE_MATHFN (J1)
 169           CASE_MATHFN (LGAMMA)
 170           CASE_MATHFN (POW10)
 171           CASE_MATHFN (SINH)
 172           CASE_MATHFN (TGAMMA)
 173           CASE_MATHFN (Y0)
 174           CASE_MATHFN (Y1)
 175             /* The above functions may set errno differently with float
 176                input or output so this transformation is not safe with
 177                -fmath-errno.  */
 178             if (flag_errno_math)
 179               break;
 180           CASE_MATHFN (ACOS)
 181           CASE_MATHFN (ACOSH)
 182           CASE_MATHFN (ASIN)
 183           CASE_MATHFN (ASINH)
 184           CASE_MATHFN (ATAN)
 185           CASE_MATHFN (ATANH)
 186           CASE_MATHFN (CBRT)
 187           CASE_MATHFN (COS)
 188           CASE_MATHFN (ERF)
 189           CASE_MATHFN (ERFC)
 190           CASE_MATHFN (FABS)
 191           CASE_MATHFN (LOG)
 192           CASE_MATHFN (LOG10)
 193           CASE_MATHFN (LOG2)
 194           CASE_MATHFN (LOG1P)
 195           CASE_MATHFN (LOGB)
 196           CASE_MATHFN (SIN)
 197           CASE_MATHFN (SQRT)
 198           CASE_MATHFN (TAN)
 199           CASE_MATHFN (TANH)
 200 #undef CASE_MATHFN
 201             {
 202               tree arg0 = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 203               tree newtype = type;
 204
 205               /* We have (outertype)sqrt((innertype)x).  Choose the wider mode from
 206                  the both as the safe type for operation.  */
 207               if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (type))
 208                 newtype = TREE_TYPE (arg0);
 209
 210               /* Be careful about integer to fp conversions.
 211                  These may overflow still.  */
 212               if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 213                   && TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 214                   && (TYPE_MODE (newtype) == TYPE_MODE (double_type_node)
 215                       || TYPE_MODE (newtype) == TYPE_MODE (float_type_node)))
 216                 {
 217                   tree fn = mathfn_built_in (newtype, fcode);
 218
 219                   if (fn)
 220                   {
 221                     tree arg = fold (convert_to_real (newtype, arg0));
 222                     expr = build_call_expr (fn, 1, arg);
 223                     if (newtype == type)
 224                       return expr;
 225                   }
 226                 }
 227             }
 228         default:
 229           break;
 230         }
 231     }
 232   if (optimize
 233       && (((fcode == BUILT_IN_FLOORL
 234            || fcode == BUILT_IN_CEILL
 235            || fcode == BUILT_IN_ROUNDL
 236            || fcode == BUILT_IN_RINTL
 237            || fcode == BUILT_IN_TRUNCL
 238            || fcode == BUILT_IN_NEARBYINTL)
 239           && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 240               || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 241           || ((fcode == BUILT_IN_FLOOR
 242                || fcode == BUILT_IN_CEIL
 243                || fcode == BUILT_IN_ROUND
 244                || fcode == BUILT_IN_RINT
 245                || fcode == BUILT_IN_TRUNC
 246                || fcode == BUILT_IN_NEARBYINT)
 247               && (TYPE_MODE (type) == TYPE_MODE (float_type_node)))))
 248     {
 249       tree fn = mathfn_built_in (type, fcode);
 250
 251       if (fn)
 252         {
 253           tree arg = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 254
 255           /* Make sure (type)arg0 is an extension, otherwise we could end up
 256              changing (float)floor(double d) into floorf((float)d), which is
 257              incorrect because (float)d uses round-to-nearest and can round
 258              up to the next integer.  */
 259           if (TYPE_PRECISION (type) >= TYPE_PRECISION (TREE_TYPE (arg)))
 260             return build_call_expr (fn, 1, fold (convert_to_real (type, arg)));
 261         }
 262     }
 263
 264   /* Propagate the cast into the operation.  */
 265   if (itype != type && FLOAT_TYPE_P (type))
 266     switch (TREE_CODE (expr))
 267       {
 268         /* Convert (float)-x into -(float)x.  This is safe for
 269            round-to-nearest rounding mode.  */
 270         case ABS_EXPR:
 271         case NEGATE_EXPR:
 272           if (!flag_rounding_math
 273               && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (expr)))
 274             return build1 (TREE_CODE (expr), type,
 275                            fold (convert_to_real (type,
 276                                                   TREE_OPERAND (expr, 0))));
 277           break;
 278         /* Convert (outertype)((innertype0)a+(innertype1)b)
 279            into ((newtype)a+(newtype)b) where newtype
 280            is the widest mode from all of these.  */
 281         case PLUS_EXPR:
 282         case MINUS_EXPR:
 283         case MULT_EXPR:
 284         case RDIV_EXPR:
 285            {
 286              tree arg0 = strip_float_extensions (TREE_OPERAND (expr, 0));
 287              tree arg1 = strip_float_extensions (TREE_OPERAND (expr, 1));
 288
 289              if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 290                  && FLOAT_TYPE_P (TREE_TYPE (arg1))
 291                  && DECIMAL_FLOAT_TYPE_P (itype) == DECIMAL_FLOAT_TYPE_P (type))
 292                {
 293                   tree newtype = type;
 294
 295                   if (TYPE_MODE (TREE_TYPE (arg0)) == SDmode
 296                       || TYPE_MODE (TREE_TYPE (arg1)) == SDmode
 297                       || TYPE_MODE (type) == SDmode)
 298                     newtype = dfloat32_type_node;
 299                   if (TYPE_MODE (TREE_TYPE (arg0)) == DDmode
 300                       || TYPE_MODE (TREE_TYPE (arg1)) == DDmode
 301                       || TYPE_MODE (type) == DDmode)
 302                     newtype = dfloat64_type_node;
 303                   if (TYPE_MODE (TREE_TYPE (arg0)) == TDmode
 304                       || TYPE_MODE (TREE_TYPE (arg1)) == TDmode
 305                       || TYPE_MODE (type) == TDmode)
 306                     newtype = dfloat128_type_node;
 307                   if (newtype == dfloat32_type_node
 308                       || newtype == dfloat64_type_node
 309                       || newtype == dfloat128_type_node)
 310                     {
 311                       expr = build2 (TREE_CODE (expr), newtype,
 312                                      fold (convert_to_real (newtype, arg0)),
 313                                      fold (convert_to_real (newtype, arg1)));
 314                       if (newtype == type)
 315                         return expr;
 316                       break;
 317                     }
 318
 319                   if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (newtype))
 320                     newtype = TREE_TYPE (arg0);
 321                   if (TYPE_PRECISION (TREE_TYPE (arg1)) > TYPE_PRECISION (newtype))
 322                     newtype = TREE_TYPE (arg1);
 323                   /* Sometimes this transformation is safe (cannot
 324                      change results through affecting double rounding
 325                      cases) and sometimes it is not.  If NEWTYPE is
 326                      wider than TYPE, e.g. (float)((long double)double
 327                      + (long double)double) converted to
 328                      (float)(double + double), the transformation is
 329                      unsafe regardless of the details of the types
 330                      involved; double rounding can arise if the result
 331                      of NEWTYPE arithmetic is a NEWTYPE value half way
 332                      between two representable TYPE values but the
 333                      exact value is sufficiently different (in the
 334                      right direction) for this difference to be
 335                      visible in ITYPE arithmetic.  If NEWTYPE is the
 336                      same as TYPE, however, the transformation may be
 337                      safe depending on the types involved: it is safe
 338                      if the ITYPE has strictly more than twice as many
 339                      mantissa bits as TYPE, can represent infinities
 340                      and NaNs if the TYPE can, and has sufficient
 341                      exponent range for the product or ratio of two
 342                      values representable in the TYPE to be within the
 343                      range of normal values of ITYPE.  */
 344                   if (TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 345                       && (flag_unsafe_math_optimizations
 346                           || (TYPE_PRECISION (newtype) == TYPE_PRECISION (type)
 347                               && real_can_shorten_arithmetic (TYPE_MODE (itype),
 348                                                               TYPE_MODE (type))
 349                               && !excess_precision_type (newtype))))
 350                     {
 351                       expr = build2 (TREE_CODE (expr), newtype,
 352                                      fold (convert_to_real (newtype, arg0)),
 353                                      fold (convert_to_real (newtype, arg1)));
 354                       if (newtype == type)
 355                         return expr;
 356                     }
 357                }
 358            }
 359           break;
 360         default:
 361           break;
 362       }
 363
 364   switch (TREE_CODE (TREE_TYPE (expr)))
 365     {
 366     case REAL_TYPE:
 367       /* Ignore the conversion if we don't need to store intermediate
 368          results and neither type is a decimal float.  */
 369       return build1 ((flag_float_store
 370                      || DECIMAL_FLOAT_TYPE_P (type)
 371                      || DECIMAL_FLOAT_TYPE_P (itype))
 372                      ? CONVERT_EXPR : NOP_EXPR, type, expr);
 373
 374     case INTEGER_TYPE:
 375     case ENUMERAL_TYPE:
 376     case BOOLEAN_TYPE:
 377       return build1 (FLOAT_EXPR, type, expr);
 378
 379     case FIXED_POINT_TYPE:
 380       return build1 (FIXED_CONVERT_EXPR, type, expr);
 381
 382     case COMPLEX_TYPE:
 383       return convert (type,
 384                       fold_build1 (REALPART_EXPR,
 385                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 386
 387     case POINTER_TYPE:
 388     case REFERENCE_TYPE:
 389       error ("pointer value used where a floating point value was expected");
 390       return convert_to_real (type, integer_zero_node);
 391
 392     default:
 393       error ("aggregate value used where a float was expected");
 394       return convert_to_real (type, integer_zero_node);
 395     }
 396 }
 397
 398 /* Convert EXPR to some integer (or enum) type TYPE.
 399
 400    EXPR must be pointer, integer, discrete (enum, char, or bool), float,
 401    fixed-point or vector; in other cases error is called.
 402
 403    The result of this is always supposed to be a newly created tree node
 404    not in use in any existing structure.  */
 405
 406 tree
 407 convert_to_integer (tree type, tree expr)
 408 {
 409   enum tree_code ex_form = TREE_CODE (expr);
 410   tree intype = TREE_TYPE (expr);
 411   unsigned int inprec = TYPE_PRECISION (intype);
 412   unsigned int outprec = TYPE_PRECISION (type);
 413
 414   /* An INTEGER_TYPE cannot be incomplete, but an ENUMERAL_TYPE can
 415      be.  Consider `enum E = { a, b = (enum E) 3 };'.  */
 416   if (!COMPLETE_TYPE_P (type))
 417     {
 418       error ("conversion to incomplete type");
 419       return error_mark_node;
 420     }
 421
 422   /* Convert e.g. (long)round(d) -> lround(d).  */
 423   /* If we're converting to char, we may encounter differing behavior
 424      between converting from double->char vs double->long->char.
 425      We're in "undefined" territory but we prefer to be conservative,
 426      so only proceed in "unsafe" math mode.  */
 427   if (optimize
 428       && (flag_unsafe_math_optimizations
 429           || (long_integer_type_node
 430               && outprec >= TYPE_PRECISION (long_integer_type_node))))
 431     {
 432       tree s_expr = strip_float_extensions (expr);
 433       tree s_intype = TREE_TYPE (s_expr);
 434       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 435       tree fn = 0;
 436
 437       switch (fcode)
 438         {
 439         CASE_FLT_FN (BUILT_IN_CEIL):
 440           /* Only convert in ISO C99 mode.  */
 441           if (!TARGET_C99_FUNCTIONS)
 442             break;
 443           if (outprec < TYPE_PRECISION (integer_type_node)
 444               || (outprec == TYPE_PRECISION (integer_type_node)
 445                   && !TYPE_UNSIGNED (type)))
 446             fn = mathfn_built_in (s_intype, BUILT_IN_ICEIL);
 447           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 448                    && !TYPE_UNSIGNED (type))
 449             fn = mathfn_built_in (s_intype, BUILT_IN_LCEIL);
 450           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 451                    && !TYPE_UNSIGNED (type))
 452             fn = mathfn_built_in (s_intype, BUILT_IN_LLCEIL);
 453           break;
 454
 455         CASE_FLT_FN (BUILT_IN_FLOOR):
 456           /* Only convert in ISO C99 mode.  */
 457           if (!TARGET_C99_FUNCTIONS)
 458             break;
 459           if (outprec < TYPE_PRECISION (integer_type_node)
 460               || (outprec == TYPE_PRECISION (integer_type_node)
 461                   && !TYPE_UNSIGNED (type)))
 462             fn = mathfn_built_in (s_intype, BUILT_IN_IFLOOR);
 463           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 464                    && !TYPE_UNSIGNED (type))
 465             fn = mathfn_built_in (s_intype, BUILT_IN_LFLOOR);
 466           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 467                    && !TYPE_UNSIGNED (type))
 468             fn = mathfn_built_in (s_intype, BUILT_IN_LLFLOOR);
 469           break;
 470
 471         CASE_FLT_FN (BUILT_IN_ROUND):
 472           /* Only convert in ISO C99 mode.  */
 473           if (!TARGET_C99_FUNCTIONS)
 474             break;
 475           if (outprec < TYPE_PRECISION (integer_type_node)
 476               || (outprec == TYPE_PRECISION (integer_type_node)
 477                   && !TYPE_UNSIGNED (type)))
 478             fn = mathfn_built_in (s_intype, BUILT_IN_IROUND);
 479           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 480                    && !TYPE_UNSIGNED (type))
 481             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 482           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 483                    && !TYPE_UNSIGNED (type))
 484             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 485           break;
 486
 487         CASE_FLT_FN (BUILT_IN_NEARBYINT):
 488           /* Only convert nearbyint* if we can ignore math exceptions.  */
 489           if (flag_trapping_math)
 490             break;
 491           /* ... Fall through ...  */
 492         CASE_FLT_FN (BUILT_IN_RINT):
 493           /* Only convert in ISO C99 mode.  */
 494           if (!TARGET_C99_FUNCTIONS)
 495             break;
 496           if (outprec < TYPE_PRECISION (integer_type_node)
 497               || (outprec == TYPE_PRECISION (integer_type_node)
 498                   && !TYPE_UNSIGNED (type)))
 499             fn = mathfn_built_in (s_intype, BUILT_IN_IRINT);
 500           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 501                    && !TYPE_UNSIGNED (type))
 502             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 503           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 504                    && !TYPE_UNSIGNED (type))
 505             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 506           break;
 507
 508         CASE_FLT_FN (BUILT_IN_TRUNC):
 509           return convert_to_integer (type, CALL_EXPR_ARG (s_expr, 0));
 510
 511         default:
 512           break;
 513         }
 514
 515       if (fn)
 516         {
 517           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 518           return convert_to_integer (type, newexpr);
 519         }
 520     }
 521
 522   /* Convert (int)logb(d) -> ilogb(d).  */
 523   if (optimize
 524       && flag_unsafe_math_optimizations
 525       && !flag_trapping_math && !flag_errno_math && flag_finite_math_only
 526       && integer_type_node
 527       && (outprec > TYPE_PRECISION (integer_type_node)
 528           || (outprec == TYPE_PRECISION (integer_type_node)
 529               && !TYPE_UNSIGNED (type))))
 530     {
 531       tree s_expr = strip_float_extensions (expr);
 532       tree s_intype = TREE_TYPE (s_expr);
 533       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 534       tree fn = 0;
 535
 536       switch (fcode)
 537         {
 538         CASE_FLT_FN (BUILT_IN_LOGB):
 539           fn = mathfn_built_in (s_intype, BUILT_IN_ILOGB);
 540           break;
 541
 542         default:
 543           break;
 544         }
 545
 546       if (fn)
 547         {
 548           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 549           return convert_to_integer (type, newexpr);
 550         }
 551     }
 552
 553   switch (TREE_CODE (intype))
 554     {
 555     case POINTER_TYPE:
 556     case REFERENCE_TYPE:
 557       if (integer_zerop (expr))
 558         return build_int_cst (type, 0);
 559
 560       /* Convert to an unsigned integer of the correct width first, and from
 561          there widen/truncate to the required type.  Some targets support the
 562          coexistence of multiple valid pointer sizes, so fetch the one we need
 563          from the type.  */
 564       expr = fold_build1 (CONVERT_EXPR,
 565                           lang_hooks.types.type_for_size
 566                             (TYPE_PRECISION (intype), 0),
 567                           expr);
 568       return fold_convert (type, expr);
 569
 570     case INTEGER_TYPE:
 571     case ENUMERAL_TYPE:
 572     case BOOLEAN_TYPE:
 573     case OFFSET_TYPE:
 574       /* If this is a logical operation, which just returns 0 or 1, we can
 575          change the type of the expression.  */
 576
 577       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 578         {
 579           expr = copy_node (expr);
 580           TREE_TYPE (expr) = type;
 581           return expr;
 582         }
 583
 584       /* If we are widening the type, put in an explicit conversion.
 585          Similarly if we are not changing the width.  After this, we know
 586          we are truncating EXPR.  */
 587
 588       else if (outprec >= inprec)
 589         {
 590           enum tree_code code;
 591           tree tem;
 592
 593           /* If the precision of the EXPR's type is K bits and the
 594              destination mode has more bits, and the sign is changing,
 595              it is not safe to use a NOP_EXPR.  For example, suppose
 596              that EXPR's type is a 3-bit unsigned integer type, the
 597              TYPE is a 3-bit signed integer type, and the machine mode
 598              for the types is 8-bit QImode.  In that case, the
 599              conversion necessitates an explicit sign-extension.  In
 600              the signed-to-unsigned case the high-order bits have to
 601              be cleared.  */
 602           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 603               && (TYPE_PRECISION (TREE_TYPE (expr))
 604                   != GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (expr)))))
 605             code = CONVERT_EXPR;
 606           else
 607             code = NOP_EXPR;
 608
 609           tem = fold_unary (code, type, expr);
 610           if (tem)
 611             return tem;
 612
 613           tem = build1 (code, type, expr);
 614           TREE_NO_WARNING (tem) = 1;
 615           return tem;
 616         }
 617
 618       /* If TYPE is an enumeral type or a type with a precision less
 619          than the number of bits in its mode, do the conversion to the
 620          type corresponding to its mode, then do a nop conversion
 621          to TYPE.  */
 622       else if (TREE_CODE (type) == ENUMERAL_TYPE
 623                || outprec != GET_MODE_PRECISION (TYPE_MODE (type)))
 624         return build1 (NOP_EXPR, type,
 625                        convert (lang_hooks.types.type_for_mode
 626                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 627                                 expr));
 628
 629       /* Here detect when we can distribute the truncation down past some
 630          arithmetic.  For example, if adding two longs and converting to an
 631          int, we can equally well convert both to ints and then add.
 632          For the operations handled here, such truncation distribution
 633          is always safe.
 634          It is desirable in these cases:
 635          1) when truncating down to full-word from a larger size
 636          2) when truncating takes no work.
 637          3) when at least one operand of the arithmetic has been extended
 638          (as by C's default conversions).  In this case we need two conversions
 639          if we do the arithmetic as already requested, so we might as well
 640          truncate both and then combine.  Perhaps that way we need only one.
 641
 642          Note that in general we cannot do the arithmetic in a type
 643          shorter than the desired result of conversion, even if the operands
 644          are both extended from a shorter type, because they might overflow
 645          if combined in that type.  The exceptions to this--the times when
 646          two narrow values can be combined in their narrow type even to
 647          make a wider result--are handled by "shorten" in build_binary_op.  */
 648
 649       switch (ex_form)
 650         {
 651         case RSHIFT_EXPR:
 652           /* We can pass truncation down through right shifting
 653              when the shift count is a nonpositive constant.  */
 654           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 655               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) <= 0)
 656             goto trunc1;
 657           break;
 658
 659         case LSHIFT_EXPR:
 660           /* We can pass truncation down through left shifting
 661              when the shift count is a nonnegative constant and
 662              the target type is unsigned.  */
 663           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 664               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 665               && TYPE_UNSIGNED (type)
 666               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 667             {
 668               /* If shift count is less than the width of the truncated type,
 669                  really shift.  */
 670               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 671                 /* In this case, shifting is like multiplication.  */
 672                 goto trunc1;
 673               else
 674                 {
 675                   /* If it is >= that width, result is zero.
 676                      Handling this with trunc1 would give the wrong result:
 677                      (int) ((long long) a << 32) is well defined (as 0)
 678                      but (int) a << 32 is undefined and would get a
 679                      warning.  */
 680
 681                   tree t = build_int_cst (type, 0);
 682
 683                   /* If the original expression had side-effects, we must
 684                      preserve it.  */
 685                   if (TREE_SIDE_EFFECTS (expr))
 686                     return build2 (COMPOUND_EXPR, type, expr, t);
 687                   else
 688                     return t;
 689                 }
 690             }
 691           break;
 692
 693         case TRUNC_DIV_EXPR:
 694           {
 695             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 696             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 697
 698             /* Don't distribute unless the output precision is at least as big
 699                as the actual inputs and it has the same signedness.  */
 700             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 701                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 702                 /* If signedness of arg0 and arg1 don't match,
 703                    we can't necessarily find a type to compare them in.  */
 704                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 705                     == TYPE_UNSIGNED (TREE_TYPE (arg1)))
 706                 /* Do not change the sign of the division.  */
 707                 && (TYPE_UNSIGNED (TREE_TYPE (expr))
 708                     == TYPE_UNSIGNED (TREE_TYPE (arg0)))
 709                 /* Either require unsigned division or a division by
 710                    a constant that is not -1.  */
 711                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 712                     || (TREE_CODE (arg1) == INTEGER_CST
 713                         && !integer_all_onesp (arg1))))
 714               goto trunc1;
 715             break;
 716           }
 717
 718         case MAX_EXPR:
 719         case MIN_EXPR:
 720         case MULT_EXPR:
 721           {
 722             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 723             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 724
 725             /* Don't distribute unless the output precision is at least as big
 726                as the actual inputs.  Otherwise, the comparison of the
 727                truncated values will be wrong.  */
 728             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 729                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 730                 /* If signedness of arg0 and arg1 don't match,
 731                    we can't necessarily find a type to compare them in.  */
 732                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 733                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 734               goto trunc1;
 735             break;
 736           }
 737
 738         case PLUS_EXPR:
 739         case MINUS_EXPR:
 740         case BIT_AND_EXPR:
 741         case BIT_IOR_EXPR:
 742         case BIT_XOR_EXPR:
 743         trunc1:
 744           {
 745             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 746             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 747
 748             /* Do not try to narrow operands of pointer subtraction;
 749                that will interfere with other folding.  */
 750             if (ex_form == MINUS_EXPR
 751                 && CONVERT_EXPR_P (arg0)
 752                 && CONVERT_EXPR_P (arg1)
 753                 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 0)))
 754                 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0))))
 755               break;
 756
 757             if (outprec >= BITS_PER_WORD
 758                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 759                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 760                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 761               {
 762                 /* Do the arithmetic in type TYPEX,
 763                    then convert result to TYPE.  */
 764                 tree typex = type;
 765
 766                 /* Can't do arithmetic in enumeral types
 767                    so use an integer type that will hold the values.  */
 768                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 769                   typex = lang_hooks.types.type_for_size
 770                     (TYPE_PRECISION (typex), TYPE_UNSIGNED (typex));
 771
 772                 /* But now perhaps TYPEX is as wide as INPREC.
 773                    In that case, do nothing special here.
 774                    (Otherwise would recurse infinitely in convert.  */
 775                 if (TYPE_PRECISION (typex) != inprec)
 776                   {
 777                     /* Don't do unsigned arithmetic where signed was wanted,
 778                        or vice versa.
 779                        Exception: if both of the original operands were
 780                        unsigned then we can safely do the work as unsigned.
 781                        Exception: shift operations take their type solely
 782                        from the first argument.
 783                        Exception: the LSHIFT_EXPR case above requires that
 784                        we perform this operation unsigned lest we produce
 785                        signed-overflow undefinedness.
 786                        And we may need to do it as unsigned
 787                        if we truncate to the original size.  */
 788                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 789                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 790                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 791                                 || ex_form == LSHIFT_EXPR
 792                                 || ex_form == RSHIFT_EXPR
 793                                 || ex_form == LROTATE_EXPR
 794                                 || ex_form == RROTATE_EXPR))
 795                         || ex_form == LSHIFT_EXPR
 796                         /* If we have !flag_wrapv, and either ARG0 or
 797                            ARG1 is of a signed type, we have to do
 798                            PLUS_EXPR, MINUS_EXPR or MULT_EXPR in an unsigned
 799                            type in case the operation in outprec precision
 800                            could overflow.  Otherwise, we would introduce
 801                            signed-overflow undefinedness.  */
 802                         || ((!TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg0))
 803                              || !TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1)))
 804                             && ((TYPE_PRECISION (TREE_TYPE (arg0)) * 2u
 805                                  > outprec)
 806                                 || (TYPE_PRECISION (TREE_TYPE (arg1)) * 2u
 807                                     > outprec))
 808                             && (ex_form == PLUS_EXPR
 809                                 || ex_form == MINUS_EXPR
 810                                 || ex_form == MULT_EXPR)))
 811                       typex = unsigned_type_for (typex);
 812                     else
 813                       typex = signed_type_for (typex);
 814                     return convert (type,
 815                                     fold_build2 (ex_form, typex,
 816                                                  convert (typex, arg0),
 817                                                  convert (typex, arg1)));
 818                   }
 819               }
 820           }
 821           break;
 822
 823         case NEGATE_EXPR:
 824         case BIT_NOT_EXPR:
 825           /* This is not correct for ABS_EXPR,
 826              since we must test the sign before truncation.  */
 827           {
 828             tree typex = unsigned_type_for (type);
 829             return convert (type,
 830                             fold_build1 (ex_form, typex,
 831                                          convert (typex,
 832                                                   TREE_OPERAND (expr, 0))));
 833           }
 834
 835         case NOP_EXPR:
 836           /* Don't introduce a
 837              "can't convert between vector values of different size" error.  */
 838           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 839               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 840                   != GET_MODE_SIZE (TYPE_MODE (type))))
 841             break;
 842           /* If truncating after truncating, might as well do all at once.
 843              If truncating after extending, we may get rid of wasted work.  */
 844           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 845
 846         case COND_EXPR:
 847           /* It is sometimes worthwhile to push the narrowing down through
 848              the conditional and never loses.  A COND_EXPR may have a throw
 849              as one operand, which then has void type.  Just leave void
 850              operands as they are.  */
 851           return fold_build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 852                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 1)))
 853                               ? TREE_OPERAND (expr, 1)
 854                               : convert (type, TREE_OPERAND (expr, 1)),
 855                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 2)))
 856                               ? TREE_OPERAND (expr, 2)
 857                               : convert (type, TREE_OPERAND (expr, 2)));
 858
 859         default:
 860           break;
 861         }
 862
 863       return build1 (CONVERT_EXPR, type, expr);
 864
 865     case REAL_TYPE:
 866       return build1 (FIX_TRUNC_EXPR, type, expr);
 867
 868     case FIXED_POINT_TYPE:
 869       return build1 (FIXED_CONVERT_EXPR, type, expr);
 870
 871     case COMPLEX_TYPE:
 872       return convert (type,
 873                       fold_build1 (REALPART_EXPR,
 874                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 875
 876     case VECTOR_TYPE:
 877       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 878         {
 879           error ("can%'t convert between vector values of different size");
 880           return error_mark_node;
 881         }
 882       return build1 (VIEW_CONVERT_EXPR, type, expr);
 883
 884     default:
 885       error ("aggregate value used where an integer was expected");
 886       return convert (type, integer_zero_node);
 887     }
 888 }
 889
 890 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 891
 892 tree
 893 convert_to_complex (tree type, tree expr)
 894 {
 895   tree subtype = TREE_TYPE (type);
 896
 897   switch (TREE_CODE (TREE_TYPE (expr)))
 898     {
 899     case REAL_TYPE:
 900     case FIXED_POINT_TYPE:
 901     case INTEGER_TYPE:
 902     case ENUMERAL_TYPE:
 903     case BOOLEAN_TYPE:
 904       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 905                      convert (subtype, integer_zero_node));
 906
 907     case COMPLEX_TYPE:
 908       {
 909         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 910
 911         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 912           return expr;
 913         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 914           return fold_build2 (COMPLEX_EXPR, type,
 915                               convert (subtype, TREE_OPERAND (expr, 0)),
 916                               convert (subtype, TREE_OPERAND (expr, 1)));
 917         else
 918           {
 919             expr = save_expr (expr);
 920             return
 921               fold_build2 (COMPLEX_EXPR, type,
 922                            convert (subtype,
 923                                     fold_build1 (REALPART_EXPR,
 924                                                  TREE_TYPE (TREE_TYPE (expr)),
 925                                                  expr)),
 926                            convert (subtype,
 927                                     fold_build1 (IMAGPART_EXPR,
 928                                                  TREE_TYPE (TREE_TYPE (expr)),
 929                                                  expr)));
 930           }
 931       }
 932
 933     case POINTER_TYPE:
 934     case REFERENCE_TYPE:
 935       error ("pointer value used where a complex was expected");
 936       return convert_to_complex (type, integer_zero_node);
 937
 938     default:
 939       error ("aggregate value used where a complex was expected");
 940       return convert_to_complex (type, integer_zero_node);
 941     }
 942 }
 943
 944 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 945
 946 tree
 947 convert_to_vector (tree type, tree expr)
 948 {
 949   switch (TREE_CODE (TREE_TYPE (expr)))
 950     {
 951     case INTEGER_TYPE:
 952     case VECTOR_TYPE:
 953       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 954         {
 955           error ("can%'t convert between vector values of different size");
 956           return error_mark_node;
 957         }
 958       return build1 (VIEW_CONVERT_EXPR, type, expr);
 959
 960     default:
 961       error ("can%'t convert value to a vector");
 962       return error_mark_node;
 963     }
 964 }
 965
 966 /* Convert EXPR to some fixed-point type TYPE.
 967
 968    EXPR must be fixed-point, float, integer, or enumeral;
 969    in other cases error is called.  */
 970
 971 tree
 972 convert_to_fixed (tree type, tree expr)
 973 {
 974   if (integer_zerop (expr))
 975     {
 976       tree fixed_zero_node = build_fixed (type, FCONST0 (TYPE_MODE (type)));
 977       return fixed_zero_node;
 978     }
 979   else if (integer_onep (expr) && ALL_SCALAR_ACCUM_MODE_P (TYPE_MODE (type)))
 980     {
 981       tree fixed_one_node = build_fixed (type, FCONST1 (TYPE_MODE (type)));
 982       return fixed_one_node;
 983     }
 984
 985   switch (TREE_CODE (TREE_TYPE (expr)))
 986     {
 987     case FIXED_POINT_TYPE:
 988     case INTEGER_TYPE:
 989     case ENUMERAL_TYPE:
 990     case BOOLEAN_TYPE:
 991     case REAL_TYPE:
 992       return build1 (FIXED_CONVERT_EXPR, type, expr);
 993
 994     case COMPLEX_TYPE:
 995       return convert (type,
 996                       fold_build1 (REALPART_EXPR,
 997                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 998
 999     default:
1000       error ("aggregate value used where a fixed-point was expected");
1001       return error_mark_node;
1002     }
1003 }