gcc/convert.c

   1 /* Utility routines for data type conversion for GCC.
   2    Copyright (C) 1987-2014 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 "stor-layout.h"
  30 #include "flags.h"
  31 #include "convert.h"
  32 #include "diagnostic-core.h"
  33 #include "target.h"
  34 #include "langhooks.h"
  35 #include "builtins.h"
  36 #include "ubsan.h"
  37
  38 /* Convert EXPR to some pointer or reference type TYPE.
  39    EXPR must be pointer, reference, integer, enumeral, or literal zero;
  40    in other cases error is called.  */
  41
  42 tree
  43 convert_to_pointer (tree type, tree expr)
  44 {
  45   location_t loc = EXPR_LOCATION (expr);
  46   if (TREE_TYPE (expr) == type)
  47     return expr;
  48
  49   switch (TREE_CODE (TREE_TYPE (expr)))
  50     {
  51     case POINTER_TYPE:
  52     case REFERENCE_TYPE:
  53       {
  54         /* If the pointers point to different address spaces, conversion needs
  55            to be done via a ADDR_SPACE_CONVERT_EXPR instead of a NOP_EXPR.  */
  56         addr_space_t to_as = TYPE_ADDR_SPACE (TREE_TYPE (type));
  57         addr_space_t from_as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (expr)));
  58
  59         if (to_as == from_as)
  60           return fold_build1_loc (loc, NOP_EXPR, type, expr);
  61         else
  62           return fold_build1_loc (loc, ADDR_SPACE_CONVERT_EXPR, type, expr);
  63       }
  64
  65     case INTEGER_TYPE:
  66     case ENUMERAL_TYPE:
  67     case BOOLEAN_TYPE:
  68       {
  69         /* If the input precision differs from the target pointer type
  70            precision, first convert the input expression to an integer type of
  71            the target precision.  Some targets, e.g. VMS, need several pointer
  72            sizes to coexist so the latter isn't necessarily POINTER_SIZE.  */
  73         unsigned int pprec = TYPE_PRECISION (type);
  74         unsigned int eprec = TYPE_PRECISION (TREE_TYPE (expr));
  75
  76         if (eprec != pprec)
  77           expr = fold_build1_loc (loc, NOP_EXPR,
  78                               lang_hooks.types.type_for_size (pprec, 0),
  79                               expr);
  80       }
  81
  82       return fold_build1_loc (loc, CONVERT_EXPR, type, expr);
  83
  84     default:
  85       error ("cannot convert to a pointer type");
  86       return convert_to_pointer (type, integer_zero_node);
  87     }
  88 }
  89
  90
  91 /* Convert EXPR to some floating-point type TYPE.
  92
  93    EXPR must be float, fixed-point, integer, or enumeral;
  94    in other cases error is called.  */
  95
  96 tree
  97 convert_to_real (tree type, tree expr)
  98 {
  99   enum built_in_function fcode = builtin_mathfn_code (expr);
 100   tree itype = TREE_TYPE (expr);
 101
 102   /* Disable until we figure out how to decide whether the functions are
 103      present in runtime.  */
 104   /* Convert (float)sqrt((double)x) where x is float into sqrtf(x) */
 105   if (optimize
 106       && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 107           || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 108     {
 109       switch (fcode)
 110         {
 111 #define CASE_MATHFN(FN) case BUILT_IN_##FN: case BUILT_IN_##FN##L:
 112           CASE_MATHFN (COSH)
 113           CASE_MATHFN (EXP)
 114           CASE_MATHFN (EXP10)
 115           CASE_MATHFN (EXP2)
 116           CASE_MATHFN (EXPM1)
 117           CASE_MATHFN (GAMMA)
 118           CASE_MATHFN (J0)
 119           CASE_MATHFN (J1)
 120           CASE_MATHFN (LGAMMA)
 121           CASE_MATHFN (POW10)
 122           CASE_MATHFN (SINH)
 123           CASE_MATHFN (TGAMMA)
 124           CASE_MATHFN (Y0)
 125           CASE_MATHFN (Y1)
 126             /* The above functions may set errno differently with float
 127                input or output so this transformation is not safe with
 128                -fmath-errno.  */
 129             if (flag_errno_math)
 130               break;
 131           CASE_MATHFN (ACOS)
 132           CASE_MATHFN (ACOSH)
 133           CASE_MATHFN (ASIN)
 134           CASE_MATHFN (ASINH)
 135           CASE_MATHFN (ATAN)
 136           CASE_MATHFN (ATANH)
 137           CASE_MATHFN (CBRT)
 138           CASE_MATHFN (COS)
 139           CASE_MATHFN (ERF)
 140           CASE_MATHFN (ERFC)
 141           CASE_MATHFN (LOG)
 142           CASE_MATHFN (LOG10)
 143           CASE_MATHFN (LOG2)
 144           CASE_MATHFN (LOG1P)
 145           CASE_MATHFN (SIN)
 146           CASE_MATHFN (TAN)
 147           CASE_MATHFN (TANH)
 148             /* The above functions are not safe to do this conversion.  */
 149             if (!flag_unsafe_math_optimizations)
 150               break;
 151           CASE_MATHFN (SQRT)
 152           CASE_MATHFN (FABS)
 153           CASE_MATHFN (LOGB)
 154 #undef CASE_MATHFN
 155             {
 156               tree arg0 = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 157               tree newtype = type;
 158
 159               /* We have (outertype)sqrt((innertype)x).  Choose the wider mode from
 160                  the both as the safe type for operation.  */
 161               if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (type))
 162                 newtype = TREE_TYPE (arg0);
 163
 164               /* We consider to convert
 165
 166                      (T1) sqrtT2 ((T2) exprT3)
 167                  to
 168                      (T1) sqrtT4 ((T4) exprT3)
 169
 170                   , where T1 is TYPE, T2 is ITYPE, T3 is TREE_TYPE (ARG0),
 171                  and T4 is NEWTYPE.  All those types are of floating point types.
 172                  T4 (NEWTYPE) should be narrower than T2 (ITYPE). This conversion
 173                  is safe only if P1 >= P2*2+2, where P1 and P2 are precisions of
 174                  T2 and T4.  See the following URL for a reference:
 175                  http://stackoverflow.com/questions/9235456/determining-
 176                  floating-point-square-root
 177                  */
 178               if ((fcode == BUILT_IN_SQRT || fcode == BUILT_IN_SQRTL)
 179                   && !flag_unsafe_math_optimizations)
 180                 {
 181                   /* The following conversion is unsafe even the precision condition
 182                      below is satisfied:
 183
 184                      (float) sqrtl ((long double) double_val) -> (float) sqrt (double_val)
 185                     */
 186                   if (TYPE_MODE (type) != TYPE_MODE (newtype))
 187                     break;
 188
 189                   int p1 = REAL_MODE_FORMAT (TYPE_MODE (itype))->p;
 190                   int p2 = REAL_MODE_FORMAT (TYPE_MODE (newtype))->p;
 191                   if (p1 < p2 * 2 + 2)
 192                     break;
 193                 }
 194
 195               /* Be careful about integer to fp conversions.
 196                  These may overflow still.  */
 197               if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 198                   && TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 199                   && (TYPE_MODE (newtype) == TYPE_MODE (double_type_node)
 200                       || TYPE_MODE (newtype) == TYPE_MODE (float_type_node)))
 201                 {
 202                   tree fn = mathfn_built_in (newtype, fcode);
 203
 204                   if (fn)
 205                   {
 206                     tree arg = fold (convert_to_real (newtype, arg0));
 207                     expr = build_call_expr (fn, 1, arg);
 208                     if (newtype == type)
 209                       return expr;
 210                   }
 211                 }
 212             }
 213         default:
 214           break;
 215         }
 216     }
 217   if (optimize
 218       && (((fcode == BUILT_IN_FLOORL
 219            || fcode == BUILT_IN_CEILL
 220            || fcode == BUILT_IN_ROUNDL
 221            || fcode == BUILT_IN_RINTL
 222            || fcode == BUILT_IN_TRUNCL
 223            || fcode == BUILT_IN_NEARBYINTL)
 224           && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 225               || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 226           || ((fcode == BUILT_IN_FLOOR
 227                || fcode == BUILT_IN_CEIL
 228                || fcode == BUILT_IN_ROUND
 229                || fcode == BUILT_IN_RINT
 230                || fcode == BUILT_IN_TRUNC
 231                || fcode == BUILT_IN_NEARBYINT)
 232               && (TYPE_MODE (type) == TYPE_MODE (float_type_node)))))
 233     {
 234       tree fn = mathfn_built_in (type, fcode);
 235
 236       if (fn)
 237         {
 238           tree arg = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 239
 240           /* Make sure (type)arg0 is an extension, otherwise we could end up
 241              changing (float)floor(double d) into floorf((float)d), which is
 242              incorrect because (float)d uses round-to-nearest and can round
 243              up to the next integer.  */
 244           if (TYPE_PRECISION (type) >= TYPE_PRECISION (TREE_TYPE (arg)))
 245             return build_call_expr (fn, 1, fold (convert_to_real (type, arg)));
 246         }
 247     }
 248
 249   /* Propagate the cast into the operation.  */
 250   if (itype != type && FLOAT_TYPE_P (type))
 251     switch (TREE_CODE (expr))
 252       {
 253         /* Convert (float)-x into -(float)x.  This is safe for
 254            round-to-nearest rounding mode when the inner type is float.  */
 255         case ABS_EXPR:
 256         case NEGATE_EXPR:
 257           if (!flag_rounding_math
 258               && FLOAT_TYPE_P (itype)
 259               && TYPE_PRECISION (type) < TYPE_PRECISION (itype))
 260             return build1 (TREE_CODE (expr), type,
 261                            fold (convert_to_real (type,
 262                                                   TREE_OPERAND (expr, 0))));
 263           break;
 264         /* Convert (outertype)((innertype0)a+(innertype1)b)
 265            into ((newtype)a+(newtype)b) where newtype
 266            is the widest mode from all of these.  */
 267         case PLUS_EXPR:
 268         case MINUS_EXPR:
 269         case MULT_EXPR:
 270         case RDIV_EXPR:
 271            {
 272              tree arg0 = strip_float_extensions (TREE_OPERAND (expr, 0));
 273              tree arg1 = strip_float_extensions (TREE_OPERAND (expr, 1));
 274
 275              if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 276                  && FLOAT_TYPE_P (TREE_TYPE (arg1))
 277                  && DECIMAL_FLOAT_TYPE_P (itype) == DECIMAL_FLOAT_TYPE_P (type))
 278                {
 279                   tree newtype = type;
 280
 281                   if (TYPE_MODE (TREE_TYPE (arg0)) == SDmode
 282                       || TYPE_MODE (TREE_TYPE (arg1)) == SDmode
 283                       || TYPE_MODE (type) == SDmode)
 284                     newtype = dfloat32_type_node;
 285                   if (TYPE_MODE (TREE_TYPE (arg0)) == DDmode
 286                       || TYPE_MODE (TREE_TYPE (arg1)) == DDmode
 287                       || TYPE_MODE (type) == DDmode)
 288                     newtype = dfloat64_type_node;
 289                   if (TYPE_MODE (TREE_TYPE (arg0)) == TDmode
 290                       || TYPE_MODE (TREE_TYPE (arg1)) == TDmode
 291                       || TYPE_MODE (type) == TDmode)
 292                     newtype = dfloat128_type_node;
 293                   if (newtype == dfloat32_type_node
 294                       || newtype == dfloat64_type_node
 295                       || newtype == dfloat128_type_node)
 296                     {
 297                       expr = build2 (TREE_CODE (expr), newtype,
 298                                      fold (convert_to_real (newtype, arg0)),
 299                                      fold (convert_to_real (newtype, arg1)));
 300                       if (newtype == type)
 301                         return expr;
 302                       break;
 303                     }
 304
 305                   if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (newtype))
 306                     newtype = TREE_TYPE (arg0);
 307                   if (TYPE_PRECISION (TREE_TYPE (arg1)) > TYPE_PRECISION (newtype))
 308                     newtype = TREE_TYPE (arg1);
 309                   /* Sometimes this transformation is safe (cannot
 310                      change results through affecting double rounding
 311                      cases) and sometimes it is not.  If NEWTYPE is
 312                      wider than TYPE, e.g. (float)((long double)double
 313                      + (long double)double) converted to
 314                      (float)(double + double), the transformation is
 315                      unsafe regardless of the details of the types
 316                      involved; double rounding can arise if the result
 317                      of NEWTYPE arithmetic is a NEWTYPE value half way
 318                      between two representable TYPE values but the
 319                      exact value is sufficiently different (in the
 320                      right direction) for this difference to be
 321                      visible in ITYPE arithmetic.  If NEWTYPE is the
 322                      same as TYPE, however, the transformation may be
 323                      safe depending on the types involved: it is safe
 324                      if the ITYPE has strictly more than twice as many
 325                      mantissa bits as TYPE, can represent infinities
 326                      and NaNs if the TYPE can, and has sufficient
 327                      exponent range for the product or ratio of two
 328                      values representable in the TYPE to be within the
 329                      range of normal values of ITYPE.  */
 330                   if (TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 331                       && (flag_unsafe_math_optimizations
 332                           || (TYPE_PRECISION (newtype) == TYPE_PRECISION (type)
 333                               && real_can_shorten_arithmetic (TYPE_MODE (itype),
 334                                                               TYPE_MODE (type))
 335                               && !excess_precision_type (newtype))))
 336                     {
 337                       expr = build2 (TREE_CODE (expr), newtype,
 338                                      fold (convert_to_real (newtype, arg0)),
 339                                      fold (convert_to_real (newtype, arg1)));
 340                       if (newtype == type)
 341                         return expr;
 342                     }
 343                }
 344            }
 345           break;
 346         default:
 347           break;
 348       }
 349
 350   switch (TREE_CODE (TREE_TYPE (expr)))
 351     {
 352     case REAL_TYPE:
 353       /* Ignore the conversion if we don't need to store intermediate
 354          results and neither type is a decimal float.  */
 355       return build1 ((flag_float_store
 356                      || DECIMAL_FLOAT_TYPE_P (type)
 357                      || DECIMAL_FLOAT_TYPE_P (itype))
 358                      ? CONVERT_EXPR : NOP_EXPR, type, expr);
 359
 360     case INTEGER_TYPE:
 361     case ENUMERAL_TYPE:
 362     case BOOLEAN_TYPE:
 363       return build1 (FLOAT_EXPR, type, expr);
 364
 365     case FIXED_POINT_TYPE:
 366       return build1 (FIXED_CONVERT_EXPR, type, expr);
 367
 368     case COMPLEX_TYPE:
 369       return convert (type,
 370                       fold_build1 (REALPART_EXPR,
 371                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 372
 373     case POINTER_TYPE:
 374     case REFERENCE_TYPE:
 375       error ("pointer value used where a floating point value was expected");
 376       return convert_to_real (type, integer_zero_node);
 377
 378     default:
 379       error ("aggregate value used where a float was expected");
 380       return convert_to_real (type, integer_zero_node);
 381     }
 382 }
 383
 384 /* Convert EXPR to some integer (or enum) type TYPE.
 385
 386    EXPR must be pointer, integer, discrete (enum, char, or bool), float,
 387    fixed-point or vector; in other cases error is called.
 388
 389    The result of this is always supposed to be a newly created tree node
 390    not in use in any existing structure.  */
 391
 392 tree
 393 convert_to_integer (tree type, tree expr)
 394 {
 395   enum tree_code ex_form = TREE_CODE (expr);
 396   tree intype = TREE_TYPE (expr);
 397   unsigned int inprec = element_precision (intype);
 398   unsigned int outprec = element_precision (type);
 399   location_t loc = EXPR_LOCATION (expr);
 400
 401   /* An INTEGER_TYPE cannot be incomplete, but an ENUMERAL_TYPE can
 402      be.  Consider `enum E = { a, b = (enum E) 3 };'.  */
 403   if (!COMPLETE_TYPE_P (type))
 404     {
 405       error ("conversion to incomplete type");
 406       return error_mark_node;
 407     }
 408
 409   /* Convert e.g. (long)round(d) -> lround(d).  */
 410   /* If we're converting to char, we may encounter differing behavior
 411      between converting from double->char vs double->long->char.
 412      We're in "undefined" territory but we prefer to be conservative,
 413      so only proceed in "unsafe" math mode.  */
 414   if (optimize
 415       && (flag_unsafe_math_optimizations
 416           || (long_integer_type_node
 417               && outprec >= TYPE_PRECISION (long_integer_type_node))))
 418     {
 419       tree s_expr = strip_float_extensions (expr);
 420       tree s_intype = TREE_TYPE (s_expr);
 421       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 422       tree fn = 0;
 423
 424       switch (fcode)
 425         {
 426         CASE_FLT_FN (BUILT_IN_CEIL):
 427           /* Only convert in ISO C99 mode.  */
 428           if (!targetm.libc_has_function (function_c99_misc))
 429             break;
 430           if (outprec < TYPE_PRECISION (integer_type_node)
 431               || (outprec == TYPE_PRECISION (integer_type_node)
 432                   && !TYPE_UNSIGNED (type)))
 433             fn = mathfn_built_in (s_intype, BUILT_IN_ICEIL);
 434           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 435                    && !TYPE_UNSIGNED (type))
 436             fn = mathfn_built_in (s_intype, BUILT_IN_LCEIL);
 437           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 438                    && !TYPE_UNSIGNED (type))
 439             fn = mathfn_built_in (s_intype, BUILT_IN_LLCEIL);
 440           break;
 441
 442         CASE_FLT_FN (BUILT_IN_FLOOR):
 443           /* Only convert in ISO C99 mode.  */
 444           if (!targetm.libc_has_function (function_c99_misc))
 445             break;
 446           if (outprec < TYPE_PRECISION (integer_type_node)
 447               || (outprec == TYPE_PRECISION (integer_type_node)
 448                   && !TYPE_UNSIGNED (type)))
 449             fn = mathfn_built_in (s_intype, BUILT_IN_IFLOOR);
 450           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 451                    && !TYPE_UNSIGNED (type))
 452             fn = mathfn_built_in (s_intype, BUILT_IN_LFLOOR);
 453           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 454                    && !TYPE_UNSIGNED (type))
 455             fn = mathfn_built_in (s_intype, BUILT_IN_LLFLOOR);
 456           break;
 457
 458         CASE_FLT_FN (BUILT_IN_ROUND):
 459           /* Only convert in ISO C99 mode and with -fno-math-errno.  */
 460           if (!targetm.libc_has_function (function_c99_misc) || flag_errno_math)
 461             break;
 462           if (outprec < TYPE_PRECISION (integer_type_node)
 463               || (outprec == TYPE_PRECISION (integer_type_node)
 464                   && !TYPE_UNSIGNED (type)))
 465             fn = mathfn_built_in (s_intype, BUILT_IN_IROUND);
 466           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 467                    && !TYPE_UNSIGNED (type))
 468             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 469           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 470                    && !TYPE_UNSIGNED (type))
 471             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 472           break;
 473
 474         CASE_FLT_FN (BUILT_IN_NEARBYINT):
 475           /* Only convert nearbyint* if we can ignore math exceptions.  */
 476           if (flag_trapping_math)
 477             break;
 478           /* ... Fall through ...  */
 479         CASE_FLT_FN (BUILT_IN_RINT):
 480           /* Only convert in ISO C99 mode and with -fno-math-errno.  */
 481           if (!targetm.libc_has_function (function_c99_misc) || flag_errno_math)
 482             break;
 483           if (outprec < TYPE_PRECISION (integer_type_node)
 484               || (outprec == TYPE_PRECISION (integer_type_node)
 485                   && !TYPE_UNSIGNED (type)))
 486             fn = mathfn_built_in (s_intype, BUILT_IN_IRINT);
 487           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 488                    && !TYPE_UNSIGNED (type))
 489             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 490           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 491                    && !TYPE_UNSIGNED (type))
 492             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 493           break;
 494
 495         CASE_FLT_FN (BUILT_IN_TRUNC):
 496           return convert_to_integer (type, CALL_EXPR_ARG (s_expr, 0));
 497
 498         default:
 499           break;
 500         }
 501
 502       if (fn)
 503         {
 504           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 505           return convert_to_integer (type, newexpr);
 506         }
 507     }
 508
 509   /* Convert (int)logb(d) -> ilogb(d).  */
 510   if (optimize
 511       && flag_unsafe_math_optimizations
 512       && !flag_trapping_math && !flag_errno_math && flag_finite_math_only
 513       && integer_type_node
 514       && (outprec > TYPE_PRECISION (integer_type_node)
 515           || (outprec == TYPE_PRECISION (integer_type_node)
 516               && !TYPE_UNSIGNED (type))))
 517     {
 518       tree s_expr = strip_float_extensions (expr);
 519       tree s_intype = TREE_TYPE (s_expr);
 520       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 521       tree fn = 0;
 522
 523       switch (fcode)
 524         {
 525         CASE_FLT_FN (BUILT_IN_LOGB):
 526           fn = mathfn_built_in (s_intype, BUILT_IN_ILOGB);
 527           break;
 528
 529         default:
 530           break;
 531         }
 532
 533       if (fn)
 534         {
 535           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 536           return convert_to_integer (type, newexpr);
 537         }
 538     }
 539
 540   switch (TREE_CODE (intype))
 541     {
 542     case POINTER_TYPE:
 543     case REFERENCE_TYPE:
 544       if (integer_zerop (expr))
 545         return build_int_cst (type, 0);
 546
 547       /* Convert to an unsigned integer of the correct width first, and from
 548          there widen/truncate to the required type.  Some targets support the
 549          coexistence of multiple valid pointer sizes, so fetch the one we need
 550          from the type.  */
 551       expr = fold_build1 (CONVERT_EXPR,
 552                           lang_hooks.types.type_for_size
 553                             (TYPE_PRECISION (intype), 0),
 554                           expr);
 555       return fold_convert (type, expr);
 556
 557     case INTEGER_TYPE:
 558     case ENUMERAL_TYPE:
 559     case BOOLEAN_TYPE:
 560     case OFFSET_TYPE:
 561       /* If this is a logical operation, which just returns 0 or 1, we can
 562          change the type of the expression.  */
 563
 564       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 565         {
 566           expr = copy_node (expr);
 567           TREE_TYPE (expr) = type;
 568           return expr;
 569         }
 570
 571       /* If we are widening the type, put in an explicit conversion.
 572          Similarly if we are not changing the width.  After this, we know
 573          we are truncating EXPR.  */
 574
 575       else if (outprec >= inprec)
 576         {
 577           enum tree_code code;
 578
 579           /* If the precision of the EXPR's type is K bits and the
 580              destination mode has more bits, and the sign is changing,
 581              it is not safe to use a NOP_EXPR.  For example, suppose
 582              that EXPR's type is a 3-bit unsigned integer type, the
 583              TYPE is a 3-bit signed integer type, and the machine mode
 584              for the types is 8-bit QImode.  In that case, the
 585              conversion necessitates an explicit sign-extension.  In
 586              the signed-to-unsigned case the high-order bits have to
 587              be cleared.  */
 588           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 589               && (TYPE_PRECISION (TREE_TYPE (expr))
 590                   != GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (expr)))))
 591             code = CONVERT_EXPR;
 592           else
 593             code = NOP_EXPR;
 594
 595           return fold_build1 (code, type, expr);
 596         }
 597
 598       /* If TYPE is an enumeral type or a type with a precision less
 599          than the number of bits in its mode, do the conversion to the
 600          type corresponding to its mode, then do a nop conversion
 601          to TYPE.  */
 602       else if (TREE_CODE (type) == ENUMERAL_TYPE
 603                || outprec != GET_MODE_PRECISION (TYPE_MODE (type)))
 604         return build1 (NOP_EXPR, type,
 605                        convert (lang_hooks.types.type_for_mode
 606                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 607                                 expr));
 608
 609       /* Here detect when we can distribute the truncation down past some
 610          arithmetic.  For example, if adding two longs and converting to an
 611          int, we can equally well convert both to ints and then add.
 612          For the operations handled here, such truncation distribution
 613          is always safe.
 614          It is desirable in these cases:
 615          1) when truncating down to full-word from a larger size
 616          2) when truncating takes no work.
 617          3) when at least one operand of the arithmetic has been extended
 618          (as by C's default conversions).  In this case we need two conversions
 619          if we do the arithmetic as already requested, so we might as well
 620          truncate both and then combine.  Perhaps that way we need only one.
 621
 622          Note that in general we cannot do the arithmetic in a type
 623          shorter than the desired result of conversion, even if the operands
 624          are both extended from a shorter type, because they might overflow
 625          if combined in that type.  The exceptions to this--the times when
 626          two narrow values can be combined in their narrow type even to
 627          make a wider result--are handled by "shorten" in build_binary_op.  */
 628
 629       switch (ex_form)
 630         {
 631         case RSHIFT_EXPR:
 632           /* We can pass truncation down through right shifting
 633              when the shift count is a nonpositive constant.  */
 634           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 635               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) <= 0)
 636             goto trunc1;
 637           break;
 638
 639         case LSHIFT_EXPR:
 640           /* We can pass truncation down through left shifting
 641              when the shift count is a nonnegative constant and
 642              the target type is unsigned.  */
 643           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 644               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 645               && TYPE_UNSIGNED (type)
 646               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 647             {
 648               /* If shift count is less than the width of the truncated type,
 649                  really shift.  */
 650               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 651                 /* In this case, shifting is like multiplication.  */
 652                 goto trunc1;
 653               else
 654                 {
 655                   /* If it is >= that width, result is zero.
 656                      Handling this with trunc1 would give the wrong result:
 657                      (int) ((long long) a << 32) is well defined (as 0)
 658                      but (int) a << 32 is undefined and would get a
 659                      warning.  */
 660
 661                   tree t = build_int_cst (type, 0);
 662
 663                   /* If the original expression had side-effects, we must
 664                      preserve it.  */
 665                   if (TREE_SIDE_EFFECTS (expr))
 666                     return build2 (COMPOUND_EXPR, type, expr, t);
 667                   else
 668                     return t;
 669                 }
 670             }
 671           break;
 672
 673         case TRUNC_DIV_EXPR:
 674           {
 675             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 676             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 677
 678             /* Don't distribute unless the output precision is at least as big
 679                as the actual inputs and it has the same signedness.  */
 680             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 681                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 682                 /* If signedness of arg0 and arg1 don't match,
 683                    we can't necessarily find a type to compare them in.  */
 684                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 685                     == TYPE_UNSIGNED (TREE_TYPE (arg1)))
 686                 /* Do not change the sign of the division.  */
 687                 && (TYPE_UNSIGNED (TREE_TYPE (expr))
 688                     == TYPE_UNSIGNED (TREE_TYPE (arg0)))
 689                 /* Either require unsigned division or a division by
 690                    a constant that is not -1.  */
 691                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 692                     || (TREE_CODE (arg1) == INTEGER_CST
 693                         && !integer_all_onesp (arg1))))
 694               goto trunc1;
 695             break;
 696           }
 697
 698         case MAX_EXPR:
 699         case MIN_EXPR:
 700         case MULT_EXPR:
 701           {
 702             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 703             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 704
 705             /* Don't distribute unless the output precision is at least as big
 706                as the actual inputs.  Otherwise, the comparison of the
 707                truncated values will be wrong.  */
 708             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 709                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 710                 /* If signedness of arg0 and arg1 don't match,
 711                    we can't necessarily find a type to compare them in.  */
 712                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 713                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 714               goto trunc1;
 715             break;
 716           }
 717
 718         case PLUS_EXPR:
 719         case MINUS_EXPR:
 720         case BIT_AND_EXPR:
 721         case BIT_IOR_EXPR:
 722         case BIT_XOR_EXPR:
 723         trunc1:
 724           {
 725             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 726             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 727
 728             /* Do not try to narrow operands of pointer subtraction;
 729                that will interfere with other folding.  */
 730             if (ex_form == MINUS_EXPR
 731                 && CONVERT_EXPR_P (arg0)
 732                 && CONVERT_EXPR_P (arg1)
 733                 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 0)))
 734                 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0))))
 735               break;
 736
 737             if (outprec >= BITS_PER_WORD
 738                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 739                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 740                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 741               {
 742                 /* Do the arithmetic in type TYPEX,
 743                    then convert result to TYPE.  */
 744                 tree typex = type;
 745
 746                 /* Can't do arithmetic in enumeral types
 747                    so use an integer type that will hold the values.  */
 748                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 749                   typex
 750                     = lang_hooks.types.type_for_size (TYPE_PRECISION (typex),
 751                                                       TYPE_UNSIGNED (typex));
 752
 753                 /* But now perhaps TYPEX is as wide as INPREC.
 754                    In that case, do nothing special here.
 755                    (Otherwise would recurse infinitely in convert.  */
 756                 if (TYPE_PRECISION (typex) != inprec)
 757                   {
 758                     /* Don't do unsigned arithmetic where signed was wanted,
 759                        or vice versa.
 760                        Exception: if both of the original operands were
 761                        unsigned then we can safely do the work as unsigned.
 762                        Exception: shift operations take their type solely
 763                        from the first argument.
 764                        Exception: the LSHIFT_EXPR case above requires that
 765                        we perform this operation unsigned lest we produce
 766                        signed-overflow undefinedness.
 767                        And we may need to do it as unsigned
 768                        if we truncate to the original size.  */
 769                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 770                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 771                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 772                                 || ex_form == LSHIFT_EXPR
 773                                 || ex_form == RSHIFT_EXPR
 774                                 || ex_form == LROTATE_EXPR
 775                                 || ex_form == RROTATE_EXPR))
 776                         || ex_form == LSHIFT_EXPR
 777                         /* If we have !flag_wrapv, and either ARG0 or
 778                            ARG1 is of a signed type, we have to do
 779                            PLUS_EXPR, MINUS_EXPR or MULT_EXPR in an unsigned
 780                            type in case the operation in outprec precision
 781                            could overflow.  Otherwise, we would introduce
 782                            signed-overflow undefinedness.  */
 783                         || ((!TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg0))
 784                              || !TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1)))
 785                             && ((TYPE_PRECISION (TREE_TYPE (arg0)) * 2u
 786                                  > outprec)
 787                                 || (TYPE_PRECISION (TREE_TYPE (arg1)) * 2u
 788                                     > outprec))
 789                             && (ex_form == PLUS_EXPR
 790                                 || ex_form == MINUS_EXPR
 791                                 || ex_form == MULT_EXPR)))
 792                       {
 793                         if (!TYPE_UNSIGNED (typex))
 794                           typex = unsigned_type_for (typex);
 795                       }
 796                     else
 797                       {
 798                         if (TYPE_UNSIGNED (typex))
 799                           typex = signed_type_for (typex);
 800                       }
 801                     return convert (type,
 802                                     fold_build2 (ex_form, typex,
 803                                                  convert (typex, arg0),
 804                                                  convert (typex, arg1)));
 805                   }
 806               }
 807           }
 808           break;
 809
 810         case NEGATE_EXPR:
 811         case BIT_NOT_EXPR:
 812           /* This is not correct for ABS_EXPR,
 813              since we must test the sign before truncation.  */
 814           {
 815             /* Do the arithmetic in type TYPEX,
 816                then convert result to TYPE.  */
 817             tree typex = type;
 818
 819             /* Can't do arithmetic in enumeral types
 820                so use an integer type that will hold the values.  */
 821             if (TREE_CODE (typex) == ENUMERAL_TYPE)
 822               typex
 823                 = lang_hooks.types.type_for_size (TYPE_PRECISION (typex),
 824                                                   TYPE_UNSIGNED (typex));
 825
 826             if (!TYPE_UNSIGNED (typex))
 827               typex = unsigned_type_for (typex);
 828             return convert (type,
 829                             fold_build1 (ex_form, typex,
 830                                          convert (typex,
 831                                                   TREE_OPERAND (expr, 0))));
 832           }
 833
 834         case NOP_EXPR:
 835           /* Don't introduce a
 836              "can't convert between vector values of different size" error.  */
 837           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 838               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 839                   != GET_MODE_SIZE (TYPE_MODE (type))))
 840             break;
 841           /* If truncating after truncating, might as well do all at once.
 842              If truncating after extending, we may get rid of wasted work.  */
 843           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 844
 845         case COND_EXPR:
 846           /* It is sometimes worthwhile to push the narrowing down through
 847              the conditional and never loses.  A COND_EXPR may have a throw
 848              as one operand, which then has void type.  Just leave void
 849              operands as they are.  */
 850           return fold_build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 851                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 1)))
 852                               ? TREE_OPERAND (expr, 1)
 853                               : convert (type, TREE_OPERAND (expr, 1)),
 854                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 2)))
 855                               ? TREE_OPERAND (expr, 2)
 856                               : convert (type, TREE_OPERAND (expr, 2)));
 857
 858         default:
 859           break;
 860         }
 861
 862       /* When parsing long initializers, we might end up with a lot of casts.
 863          Shortcut this.  */
 864       if (TREE_CODE (expr) == INTEGER_CST)
 865         return fold_convert (type, expr);
 866       return build1 (CONVERT_EXPR, type, expr);
 867
 868     case REAL_TYPE:
 869       if (flag_sanitize & SANITIZE_FLOAT_CAST
 870           && current_function_decl != NULL_TREE
 871           && !lookup_attribute ("no_sanitize_undefined",
 872                                 DECL_ATTRIBUTES (current_function_decl)))
 873         {
 874           expr = save_expr (expr);
 875           tree check = ubsan_instrument_float_cast (loc, type, expr);
 876           expr = build1 (FIX_TRUNC_EXPR, type, expr);
 877           if (check == NULL)
 878             return expr;
 879           return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr);
 880         }
 881       else
 882         return build1 (FIX_TRUNC_EXPR, type, expr);
 883
 884     case FIXED_POINT_TYPE:
 885       return build1 (FIXED_CONVERT_EXPR, type, expr);
 886
 887     case COMPLEX_TYPE:
 888       return convert (type,
 889                       fold_build1 (REALPART_EXPR,
 890                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 891
 892     case VECTOR_TYPE:
 893       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 894         {
 895           error ("can%'t convert between vector values of different size");
 896           return error_mark_node;
 897         }
 898       return build1 (VIEW_CONVERT_EXPR, type, expr);
 899
 900     default:
 901       error ("aggregate value used where an integer was expected");
 902       return convert (type, integer_zero_node);
 903     }
 904 }
 905
 906 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 907
 908 tree
 909 convert_to_complex (tree type, tree expr)
 910 {
 911   tree subtype = TREE_TYPE (type);
 912
 913   switch (TREE_CODE (TREE_TYPE (expr)))
 914     {
 915     case REAL_TYPE:
 916     case FIXED_POINT_TYPE:
 917     case INTEGER_TYPE:
 918     case ENUMERAL_TYPE:
 919     case BOOLEAN_TYPE:
 920       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 921                      convert (subtype, integer_zero_node));
 922
 923     case COMPLEX_TYPE:
 924       {
 925         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 926
 927         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 928           return expr;
 929         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 930           return fold_build2 (COMPLEX_EXPR, type,
 931                               convert (subtype, TREE_OPERAND (expr, 0)),
 932                               convert (subtype, TREE_OPERAND (expr, 1)));
 933         else
 934           {
 935             expr = save_expr (expr);
 936             return
 937               fold_build2 (COMPLEX_EXPR, type,
 938                            convert (subtype,
 939                                     fold_build1 (REALPART_EXPR,
 940                                                  TREE_TYPE (TREE_TYPE (expr)),
 941                                                  expr)),
 942                            convert (subtype,
 943                                     fold_build1 (IMAGPART_EXPR,
 944                                                  TREE_TYPE (TREE_TYPE (expr)),
 945                                                  expr)));
 946           }
 947       }
 948
 949     case POINTER_TYPE:
 950     case REFERENCE_TYPE:
 951       error ("pointer value used where a complex was expected");
 952       return convert_to_complex (type, integer_zero_node);
 953
 954     default:
 955       error ("aggregate value used where a complex was expected");
 956       return convert_to_complex (type, integer_zero_node);
 957     }
 958 }
 959
 960 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 961
 962 tree
 963 convert_to_vector (tree type, tree expr)
 964 {
 965   switch (TREE_CODE (TREE_TYPE (expr)))
 966     {
 967     case INTEGER_TYPE:
 968     case VECTOR_TYPE:
 969       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 970         {
 971           error ("can%'t convert between vector values of different size");
 972           return error_mark_node;
 973         }
 974       return build1 (VIEW_CONVERT_EXPR, type, expr);
 975
 976     default:
 977       error ("can%'t convert value to a vector");
 978       return error_mark_node;
 979     }
 980 }
 981
 982 /* Convert EXPR to some fixed-point type TYPE.
 983
 984    EXPR must be fixed-point, float, integer, or enumeral;
 985    in other cases error is called.  */
 986
 987 tree
 988 convert_to_fixed (tree type, tree expr)
 989 {
 990   if (integer_zerop (expr))
 991     {
 992       tree fixed_zero_node = build_fixed (type, FCONST0 (TYPE_MODE (type)));
 993       return fixed_zero_node;
 994     }
 995   else if (integer_onep (expr) && ALL_SCALAR_ACCUM_MODE_P (TYPE_MODE (type)))
 996     {
 997       tree fixed_one_node = build_fixed (type, FCONST1 (TYPE_MODE (type)));
 998       return fixed_one_node;
 999     }
1000
1001   switch (TREE_CODE (TREE_TYPE (expr)))
1002     {
1003     case FIXED_POINT_TYPE:
1004     case INTEGER_TYPE:
1005     case ENUMERAL_TYPE:
1006     case BOOLEAN_TYPE:
1007     case REAL_TYPE:
1008       return build1 (FIXED_CONVERT_EXPR, type, expr);
1009
1010     case COMPLEX_TYPE:
1011       return convert (type,
1012                       fold_build1 (REALPART_EXPR,
1013                                    TREE_TYPE (TREE_TYPE (expr)), expr));
1014
1015     default:
1016       error ("aggregate value used where a fixed-point was expected");
1017       return error_mark_node;
1018     }
1019 }