gcc/convert.c

   1 /* Utility routines for data type conversion for GCC.
   2    Copyright (C) 1987-2015 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 "alias.h"
  29 #include "tree.h"
  30 #include "fold-const.h"
  31 #include "stor-layout.h"
  32 #include "flags.h"
  33 #include "convert.h"
  34 #include "diagnostic-core.h"
  35 #include "target.h"
  36 #include "langhooks.h"
  37 #include "builtins.h"
  38 #include "ubsan.h"
  39
  40 /* Convert EXPR to some pointer or reference type TYPE.
  41    EXPR must be pointer, reference, integer, enumeral, or literal zero;
  42    in other cases error is called.  */
  43
  44 tree
  45 convert_to_pointer (tree type, tree expr)
  46 {
  47   location_t loc = EXPR_LOCATION (expr);
  48   if (TREE_TYPE (expr) == type)
  49     return expr;
  50
  51   switch (TREE_CODE (TREE_TYPE (expr)))
  52     {
  53     case POINTER_TYPE:
  54     case REFERENCE_TYPE:
  55       {
  56         /* If the pointers point to different address spaces, conversion needs
  57            to be done via a ADDR_SPACE_CONVERT_EXPR instead of a NOP_EXPR.  */
  58         addr_space_t to_as = TYPE_ADDR_SPACE (TREE_TYPE (type));
  59         addr_space_t from_as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (expr)));
  60
  61         if (to_as == from_as)
  62           return fold_build1_loc (loc, NOP_EXPR, type, expr);
  63         else
  64           return fold_build1_loc (loc, ADDR_SPACE_CONVERT_EXPR, type, expr);
  65       }
  66
  67     case INTEGER_TYPE:
  68     case ENUMERAL_TYPE:
  69     case BOOLEAN_TYPE:
  70       {
  71         /* If the input precision differs from the target pointer type
  72            precision, first convert the input expression to an integer type of
  73            the target precision.  Some targets, e.g. VMS, need several pointer
  74            sizes to coexist so the latter isn't necessarily POINTER_SIZE.  */
  75         unsigned int pprec = TYPE_PRECISION (type);
  76         unsigned int eprec = TYPE_PRECISION (TREE_TYPE (expr));
  77
  78         if (eprec != pprec)
  79           expr = fold_build1_loc (loc, NOP_EXPR,
  80                               lang_hooks.types.type_for_size (pprec, 0),
  81                               expr);
  82       }
  83
  84       return fold_build1_loc (loc, CONVERT_EXPR, type, expr);
  85
  86     default:
  87       error ("cannot convert to a pointer type");
  88       return convert_to_pointer (type, integer_zero_node);
  89     }
  90 }
  91
  92
  93 /* Convert EXPR to some floating-point type TYPE.
  94
  95    EXPR must be float, fixed-point, integer, or enumeral;
  96    in other cases error is called.  */
  97
  98 tree
  99 convert_to_real (tree type, tree expr)
 100 {
 101   enum built_in_function fcode = builtin_mathfn_code (expr);
 102   tree itype = TREE_TYPE (expr);
 103
 104   if (TREE_CODE (expr) == COMPOUND_EXPR)
 105     {
 106       tree t = convert_to_real (type, TREE_OPERAND (expr, 1));
 107       if (t == TREE_OPERAND (expr, 1))
 108         return expr;
 109       return build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR, TREE_TYPE (t),
 110                          TREE_OPERAND (expr, 0), t);
 111     }
 112
 113   /* Disable until we figure out how to decide whether the functions are
 114      present in runtime.  */
 115   /* Convert (float)sqrt((double)x) where x is float into sqrtf(x) */
 116   if (optimize
 117       && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 118           || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 119     {
 120       switch (fcode)
 121         {
 122 #define CASE_MATHFN(FN) case BUILT_IN_##FN: case BUILT_IN_##FN##L:
 123           CASE_MATHFN (COSH)
 124           CASE_MATHFN (EXP)
 125           CASE_MATHFN (EXP10)
 126           CASE_MATHFN (EXP2)
 127           CASE_MATHFN (EXPM1)
 128           CASE_MATHFN (GAMMA)
 129           CASE_MATHFN (J0)
 130           CASE_MATHFN (J1)
 131           CASE_MATHFN (LGAMMA)
 132           CASE_MATHFN (POW10)
 133           CASE_MATHFN (SINH)
 134           CASE_MATHFN (TGAMMA)
 135           CASE_MATHFN (Y0)
 136           CASE_MATHFN (Y1)
 137             /* The above functions may set errno differently with float
 138                input or output so this transformation is not safe with
 139                -fmath-errno.  */
 140             if (flag_errno_math)
 141               break;
 142           CASE_MATHFN (ACOS)
 143           CASE_MATHFN (ACOSH)
 144           CASE_MATHFN (ASIN)
 145           CASE_MATHFN (ASINH)
 146           CASE_MATHFN (ATAN)
 147           CASE_MATHFN (ATANH)
 148           CASE_MATHFN (CBRT)
 149           CASE_MATHFN (COS)
 150           CASE_MATHFN (ERF)
 151           CASE_MATHFN (ERFC)
 152           CASE_MATHFN (LOG)
 153           CASE_MATHFN (LOG10)
 154           CASE_MATHFN (LOG2)
 155           CASE_MATHFN (LOG1P)
 156           CASE_MATHFN (SIN)
 157           CASE_MATHFN (TAN)
 158           CASE_MATHFN (TANH)
 159             /* The above functions are not safe to do this conversion.  */
 160             if (!flag_unsafe_math_optimizations)
 161               break;
 162           CASE_MATHFN (SQRT)
 163           CASE_MATHFN (FABS)
 164           CASE_MATHFN (LOGB)
 165 #undef CASE_MATHFN
 166             {
 167               tree arg0 = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 168               tree newtype = type;
 169
 170               /* We have (outertype)sqrt((innertype)x).  Choose the wider mode from
 171                  the both as the safe type for operation.  */
 172               if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (type))
 173                 newtype = TREE_TYPE (arg0);
 174
 175               /* We consider to convert
 176
 177                      (T1) sqrtT2 ((T2) exprT3)
 178                  to
 179                      (T1) sqrtT4 ((T4) exprT3)
 180
 181                   , where T1 is TYPE, T2 is ITYPE, T3 is TREE_TYPE (ARG0),
 182                  and T4 is NEWTYPE.  All those types are of floating point types.
 183                  T4 (NEWTYPE) should be narrower than T2 (ITYPE). This conversion
 184                  is safe only if P1 >= P2*2+2, where P1 and P2 are precisions of
 185                  T2 and T4.  See the following URL for a reference:
 186                  http://stackoverflow.com/questions/9235456/determining-
 187                  floating-point-square-root
 188                  */
 189               if ((fcode == BUILT_IN_SQRT || fcode == BUILT_IN_SQRTL)
 190                   && !flag_unsafe_math_optimizations)
 191                 {
 192                   /* The following conversion is unsafe even the precision condition
 193                      below is satisfied:
 194
 195                      (float) sqrtl ((long double) double_val) -> (float) sqrt (double_val)
 196                     */
 197                   if (TYPE_MODE (type) != TYPE_MODE (newtype))
 198                     break;
 199
 200                   int p1 = REAL_MODE_FORMAT (TYPE_MODE (itype))->p;
 201                   int p2 = REAL_MODE_FORMAT (TYPE_MODE (newtype))->p;
 202                   if (p1 < p2 * 2 + 2)
 203                     break;
 204                 }
 205
 206               /* Be careful about integer to fp conversions.
 207                  These may overflow still.  */
 208               if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 209                   && TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 210                   && (TYPE_MODE (newtype) == TYPE_MODE (double_type_node)
 211                       || TYPE_MODE (newtype) == TYPE_MODE (float_type_node)))
 212                 {
 213                   tree fn = mathfn_built_in (newtype, fcode);
 214
 215                   if (fn)
 216                   {
 217                     tree arg = fold (convert_to_real (newtype, arg0));
 218                     expr = build_call_expr (fn, 1, arg);
 219                     if (newtype == type)
 220                       return expr;
 221                   }
 222                 }
 223             }
 224         default:
 225           break;
 226         }
 227     }
 228   if (optimize
 229       && (((fcode == BUILT_IN_FLOORL
 230            || fcode == BUILT_IN_CEILL
 231            || fcode == BUILT_IN_ROUNDL
 232            || fcode == BUILT_IN_RINTL
 233            || fcode == BUILT_IN_TRUNCL
 234            || fcode == BUILT_IN_NEARBYINTL)
 235           && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 236               || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 237           || ((fcode == BUILT_IN_FLOOR
 238                || fcode == BUILT_IN_CEIL
 239                || fcode == BUILT_IN_ROUND
 240                || fcode == BUILT_IN_RINT
 241                || fcode == BUILT_IN_TRUNC
 242                || fcode == BUILT_IN_NEARBYINT)
 243               && (TYPE_MODE (type) == TYPE_MODE (float_type_node)))))
 244     {
 245       tree fn = mathfn_built_in (type, fcode);
 246
 247       if (fn)
 248         {
 249           tree arg = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 250
 251           /* Make sure (type)arg0 is an extension, otherwise we could end up
 252              changing (float)floor(double d) into floorf((float)d), which is
 253              incorrect because (float)d uses round-to-nearest and can round
 254              up to the next integer.  */
 255           if (TYPE_PRECISION (type) >= TYPE_PRECISION (TREE_TYPE (arg)))
 256             return build_call_expr (fn, 1, fold (convert_to_real (type, arg)));
 257         }
 258     }
 259
 260   /* Propagate the cast into the operation.  */
 261   if (itype != type && FLOAT_TYPE_P (type))
 262     switch (TREE_CODE (expr))
 263       {
 264         /* Convert (float)-x into -(float)x.  This is safe for
 265            round-to-nearest rounding mode when the inner type is float.  */
 266         case ABS_EXPR:
 267         case NEGATE_EXPR:
 268           if (!flag_rounding_math
 269               && FLOAT_TYPE_P (itype)
 270               && TYPE_PRECISION (type) < TYPE_PRECISION (itype))
 271             return build1 (TREE_CODE (expr), type,
 272                            fold (convert_to_real (type,
 273                                                   TREE_OPERAND (expr, 0))));
 274           break;
 275         /* Convert (outertype)((innertype0)a+(innertype1)b)
 276            into ((newtype)a+(newtype)b) where newtype
 277            is the widest mode from all of these.  */
 278         case PLUS_EXPR:
 279         case MINUS_EXPR:
 280         case MULT_EXPR:
 281         case RDIV_EXPR:
 282            {
 283              tree arg0 = strip_float_extensions (TREE_OPERAND (expr, 0));
 284              tree arg1 = strip_float_extensions (TREE_OPERAND (expr, 1));
 285
 286              if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 287                  && FLOAT_TYPE_P (TREE_TYPE (arg1))
 288                  && DECIMAL_FLOAT_TYPE_P (itype) == DECIMAL_FLOAT_TYPE_P (type))
 289                {
 290                   tree newtype = type;
 291
 292                   if (TYPE_MODE (TREE_TYPE (arg0)) == SDmode
 293                       || TYPE_MODE (TREE_TYPE (arg1)) == SDmode
 294                       || TYPE_MODE (type) == SDmode)
 295                     newtype = dfloat32_type_node;
 296                   if (TYPE_MODE (TREE_TYPE (arg0)) == DDmode
 297                       || TYPE_MODE (TREE_TYPE (arg1)) == DDmode
 298                       || TYPE_MODE (type) == DDmode)
 299                     newtype = dfloat64_type_node;
 300                   if (TYPE_MODE (TREE_TYPE (arg0)) == TDmode
 301                       || TYPE_MODE (TREE_TYPE (arg1)) == TDmode
 302                       || TYPE_MODE (type) == TDmode)
 303                     newtype = dfloat128_type_node;
 304                   if (newtype == dfloat32_type_node
 305                       || newtype == dfloat64_type_node
 306                       || newtype == dfloat128_type_node)
 307                     {
 308                       expr = build2 (TREE_CODE (expr), newtype,
 309                                      fold (convert_to_real (newtype, arg0)),
 310                                      fold (convert_to_real (newtype, arg1)));
 311                       if (newtype == type)
 312                         return expr;
 313                       break;
 314                     }
 315
 316                   if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (newtype))
 317                     newtype = TREE_TYPE (arg0);
 318                   if (TYPE_PRECISION (TREE_TYPE (arg1)) > TYPE_PRECISION (newtype))
 319                     newtype = TREE_TYPE (arg1);
 320                   /* Sometimes this transformation is safe (cannot
 321                      change results through affecting double rounding
 322                      cases) and sometimes it is not.  If NEWTYPE is
 323                      wider than TYPE, e.g. (float)((long double)double
 324                      + (long double)double) converted to
 325                      (float)(double + double), the transformation is
 326                      unsafe regardless of the details of the types
 327                      involved; double rounding can arise if the result
 328                      of NEWTYPE arithmetic is a NEWTYPE value half way
 329                      between two representable TYPE values but the
 330                      exact value is sufficiently different (in the
 331                      right direction) for this difference to be
 332                      visible in ITYPE arithmetic.  If NEWTYPE is the
 333                      same as TYPE, however, the transformation may be
 334                      safe depending on the types involved: it is safe
 335                      if the ITYPE has strictly more than twice as many
 336                      mantissa bits as TYPE, can represent infinities
 337                      and NaNs if the TYPE can, and has sufficient
 338                      exponent range for the product or ratio of two
 339                      values representable in the TYPE to be within the
 340                      range of normal values of ITYPE.  */
 341                   if (TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 342                       && (flag_unsafe_math_optimizations
 343                           || (TYPE_PRECISION (newtype) == TYPE_PRECISION (type)
 344                               && real_can_shorten_arithmetic (TYPE_MODE (itype),
 345                                                               TYPE_MODE (type))
 346                               && !excess_precision_type (newtype))))
 347                     {
 348                       expr = build2 (TREE_CODE (expr), newtype,
 349                                      fold (convert_to_real (newtype, arg0)),
 350                                      fold (convert_to_real (newtype, arg1)));
 351                       if (newtype == type)
 352                         return expr;
 353                     }
 354                }
 355            }
 356           break;
 357         default:
 358           break;
 359       }
 360
 361   switch (TREE_CODE (TREE_TYPE (expr)))
 362     {
 363     case REAL_TYPE:
 364       /* Ignore the conversion if we don't need to store intermediate
 365          results and neither type is a decimal float.  */
 366       return build1 ((flag_float_store
 367                      || DECIMAL_FLOAT_TYPE_P (type)
 368                      || DECIMAL_FLOAT_TYPE_P (itype))
 369                      ? CONVERT_EXPR : NOP_EXPR, type, expr);
 370
 371     case INTEGER_TYPE:
 372     case ENUMERAL_TYPE:
 373     case BOOLEAN_TYPE:
 374       return build1 (FLOAT_EXPR, type, expr);
 375
 376     case FIXED_POINT_TYPE:
 377       return build1 (FIXED_CONVERT_EXPR, type, expr);
 378
 379     case COMPLEX_TYPE:
 380       return convert (type,
 381                       fold_build1 (REALPART_EXPR,
 382                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 383
 384     case POINTER_TYPE:
 385     case REFERENCE_TYPE:
 386       error ("pointer value used where a floating point value was expected");
 387       return convert_to_real (type, integer_zero_node);
 388
 389     default:
 390       error ("aggregate value used where a float was expected");
 391       return convert_to_real (type, integer_zero_node);
 392     }
 393 }
 394
 395 /* Convert EXPR to some integer (or enum) type TYPE.
 396
 397    EXPR must be pointer, integer, discrete (enum, char, or bool), float,
 398    fixed-point or vector; in other cases error is called.
 399
 400    The result of this is always supposed to be a newly created tree node
 401    not in use in any existing structure.  */
 402
 403 tree
 404 convert_to_integer (tree type, tree expr)
 405 {
 406   enum tree_code ex_form = TREE_CODE (expr);
 407   tree intype = TREE_TYPE (expr);
 408   unsigned int inprec = element_precision (intype);
 409   unsigned int outprec = element_precision (type);
 410   location_t loc = EXPR_LOCATION (expr);
 411
 412   /* An INTEGER_TYPE cannot be incomplete, but an ENUMERAL_TYPE can
 413      be.  Consider `enum E = { a, b = (enum E) 3 };'.  */
 414   if (!COMPLETE_TYPE_P (type))
 415     {
 416       error ("conversion to incomplete type");
 417       return error_mark_node;
 418     }
 419
 420   if (ex_form == COMPOUND_EXPR)
 421     {
 422       tree t = convert_to_integer (type, TREE_OPERAND (expr, 1));
 423       if (t == TREE_OPERAND (expr, 1))
 424         return expr;
 425       return build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR, TREE_TYPE (t),
 426                          TREE_OPERAND (expr, 0), t);
 427     }
 428
 429   /* Convert e.g. (long)round(d) -> lround(d).  */
 430   /* If we're converting to char, we may encounter differing behavior
 431      between converting from double->char vs double->long->char.
 432      We're in "undefined" territory but we prefer to be conservative,
 433      so only proceed in "unsafe" math mode.  */
 434   if (optimize
 435       && (flag_unsafe_math_optimizations
 436           || (long_integer_type_node
 437               && outprec >= TYPE_PRECISION (long_integer_type_node))))
 438     {
 439       tree s_expr = strip_float_extensions (expr);
 440       tree s_intype = TREE_TYPE (s_expr);
 441       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 442       tree fn = 0;
 443
 444       switch (fcode)
 445         {
 446         CASE_FLT_FN (BUILT_IN_CEIL):
 447           /* Only convert in ISO C99 mode.  */
 448           if (!targetm.libc_has_function (function_c99_misc))
 449             break;
 450           if (outprec < TYPE_PRECISION (integer_type_node)
 451               || (outprec == TYPE_PRECISION (integer_type_node)
 452                   && !TYPE_UNSIGNED (type)))
 453             fn = mathfn_built_in (s_intype, BUILT_IN_ICEIL);
 454           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 455                    && !TYPE_UNSIGNED (type))
 456             fn = mathfn_built_in (s_intype, BUILT_IN_LCEIL);
 457           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 458                    && !TYPE_UNSIGNED (type))
 459             fn = mathfn_built_in (s_intype, BUILT_IN_LLCEIL);
 460           break;
 461
 462         CASE_FLT_FN (BUILT_IN_FLOOR):
 463           /* Only convert in ISO C99 mode.  */
 464           if (!targetm.libc_has_function (function_c99_misc))
 465             break;
 466           if (outprec < TYPE_PRECISION (integer_type_node)
 467               || (outprec == TYPE_PRECISION (integer_type_node)
 468                   && !TYPE_UNSIGNED (type)))
 469             fn = mathfn_built_in (s_intype, BUILT_IN_IFLOOR);
 470           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 471                    && !TYPE_UNSIGNED (type))
 472             fn = mathfn_built_in (s_intype, BUILT_IN_LFLOOR);
 473           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 474                    && !TYPE_UNSIGNED (type))
 475             fn = mathfn_built_in (s_intype, BUILT_IN_LLFLOOR);
 476           break;
 477
 478         CASE_FLT_FN (BUILT_IN_ROUND):
 479           /* Only convert in ISO C99 mode and with -fno-math-errno.  */
 480           if (!targetm.libc_has_function (function_c99_misc) || flag_errno_math)
 481             break;
 482           if (outprec < TYPE_PRECISION (integer_type_node)
 483               || (outprec == TYPE_PRECISION (integer_type_node)
 484                   && !TYPE_UNSIGNED (type)))
 485             fn = mathfn_built_in (s_intype, BUILT_IN_IROUND);
 486           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 487                    && !TYPE_UNSIGNED (type))
 488             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 489           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 490                    && !TYPE_UNSIGNED (type))
 491             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 492           break;
 493
 494         CASE_FLT_FN (BUILT_IN_NEARBYINT):
 495           /* Only convert nearbyint* if we can ignore math exceptions.  */
 496           if (flag_trapping_math)
 497             break;
 498           /* ... Fall through ...  */
 499         CASE_FLT_FN (BUILT_IN_RINT):
 500           /* Only convert in ISO C99 mode and with -fno-math-errno.  */
 501           if (!targetm.libc_has_function (function_c99_misc) || flag_errno_math)
 502             break;
 503           if (outprec < TYPE_PRECISION (integer_type_node)
 504               || (outprec == TYPE_PRECISION (integer_type_node)
 505                   && !TYPE_UNSIGNED (type)))
 506             fn = mathfn_built_in (s_intype, BUILT_IN_IRINT);
 507           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 508                    && !TYPE_UNSIGNED (type))
 509             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 510           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 511                    && !TYPE_UNSIGNED (type))
 512             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 513           break;
 514
 515         CASE_FLT_FN (BUILT_IN_TRUNC):
 516           return convert_to_integer (type, CALL_EXPR_ARG (s_expr, 0));
 517
 518         default:
 519           break;
 520         }
 521
 522       if (fn)
 523         {
 524           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 525           return convert_to_integer (type, newexpr);
 526         }
 527     }
 528
 529   /* Convert (int)logb(d) -> ilogb(d).  */
 530   if (optimize
 531       && flag_unsafe_math_optimizations
 532       && !flag_trapping_math && !flag_errno_math && flag_finite_math_only
 533       && integer_type_node
 534       && (outprec > TYPE_PRECISION (integer_type_node)
 535           || (outprec == TYPE_PRECISION (integer_type_node)
 536               && !TYPE_UNSIGNED (type))))
 537     {
 538       tree s_expr = strip_float_extensions (expr);
 539       tree s_intype = TREE_TYPE (s_expr);
 540       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 541       tree fn = 0;
 542
 543       switch (fcode)
 544         {
 545         CASE_FLT_FN (BUILT_IN_LOGB):
 546           fn = mathfn_built_in (s_intype, BUILT_IN_ILOGB);
 547           break;
 548
 549         default:
 550           break;
 551         }
 552
 553       if (fn)
 554         {
 555           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 556           return convert_to_integer (type, newexpr);
 557         }
 558     }
 559
 560   switch (TREE_CODE (intype))
 561     {
 562     case POINTER_TYPE:
 563     case REFERENCE_TYPE:
 564       if (integer_zerop (expr))
 565         return build_int_cst (type, 0);
 566
 567       /* Convert to an unsigned integer of the correct width first, and from
 568          there widen/truncate to the required type.  Some targets support the
 569          coexistence of multiple valid pointer sizes, so fetch the one we need
 570          from the type.  */
 571       expr = fold_build1 (CONVERT_EXPR,
 572                           lang_hooks.types.type_for_size
 573                             (TYPE_PRECISION (intype), 0),
 574                           expr);
 575       return fold_convert (type, expr);
 576
 577     case INTEGER_TYPE:
 578     case ENUMERAL_TYPE:
 579     case BOOLEAN_TYPE:
 580     case OFFSET_TYPE:
 581       /* If this is a logical operation, which just returns 0 or 1, we can
 582          change the type of the expression.  */
 583
 584       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 585         {
 586           expr = copy_node (expr);
 587           TREE_TYPE (expr) = type;
 588           return expr;
 589         }
 590
 591       /* If we are widening the type, put in an explicit conversion.
 592          Similarly if we are not changing the width.  After this, we know
 593          we are truncating EXPR.  */
 594
 595       else if (outprec >= inprec)
 596         {
 597           enum tree_code code;
 598
 599           /* If the precision of the EXPR's type is K bits and the
 600              destination mode has more bits, and the sign is changing,
 601              it is not safe to use a NOP_EXPR.  For example, suppose
 602              that EXPR's type is a 3-bit unsigned integer type, the
 603              TYPE is a 3-bit signed integer type, and the machine mode
 604              for the types is 8-bit QImode.  In that case, the
 605              conversion necessitates an explicit sign-extension.  In
 606              the signed-to-unsigned case the high-order bits have to
 607              be cleared.  */
 608           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 609               && (TYPE_PRECISION (TREE_TYPE (expr))
 610                   != GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (expr)))))
 611             code = CONVERT_EXPR;
 612           else
 613             code = NOP_EXPR;
 614
 615           return fold_build1 (code, type, expr);
 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
 770                     = lang_hooks.types.type_for_size (TYPE_PRECISION (typex),
 771                                                       TYPE_UNSIGNED (typex));
 772
 773                 /* But now perhaps TYPEX is as wide as INPREC.
 774                    In that case, do nothing special here.
 775                    (Otherwise would recurse infinitely in convert.  */
 776                 if (TYPE_PRECISION (typex) != inprec)
 777                   {
 778                     /* Don't do unsigned arithmetic where signed was wanted,
 779                        or vice versa.
 780                        Exception: if both of the original operands were
 781                        unsigned then we can safely do the work as unsigned.
 782                        Exception: shift operations take their type solely
 783                        from the first argument.
 784                        Exception: the LSHIFT_EXPR case above requires that
 785                        we perform this operation unsigned lest we produce
 786                        signed-overflow undefinedness.
 787                        And we may need to do it as unsigned
 788                        if we truncate to the original size.  */
 789                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 790                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 791                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 792                                 || ex_form == LSHIFT_EXPR
 793                                 || ex_form == RSHIFT_EXPR
 794                                 || ex_form == LROTATE_EXPR
 795                                 || ex_form == RROTATE_EXPR))
 796                         || ex_form == LSHIFT_EXPR
 797                         /* If we have !flag_wrapv, and either ARG0 or
 798                            ARG1 is of a signed type, we have to do
 799                            PLUS_EXPR, MINUS_EXPR or MULT_EXPR in an unsigned
 800                            type in case the operation in outprec precision
 801                            could overflow.  Otherwise, we would introduce
 802                            signed-overflow undefinedness.  */
 803                         || ((!TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg0))
 804                              || !TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1)))
 805                             && ((TYPE_PRECISION (TREE_TYPE (arg0)) * 2u
 806                                  > outprec)
 807                                 || (TYPE_PRECISION (TREE_TYPE (arg1)) * 2u
 808                                     > outprec))
 809                             && (ex_form == PLUS_EXPR
 810                                 || ex_form == MINUS_EXPR
 811                                 || ex_form == MULT_EXPR)))
 812                       {
 813                         if (!TYPE_UNSIGNED (typex))
 814                           typex = unsigned_type_for (typex);
 815                       }
 816                     else
 817                       {
 818                         if (TYPE_UNSIGNED (typex))
 819                           typex = signed_type_for (typex);
 820                       }
 821                     return convert (type,
 822                                     fold_build2 (ex_form, typex,
 823                                                  convert (typex, arg0),
 824                                                  convert (typex, arg1)));
 825                   }
 826               }
 827           }
 828           break;
 829
 830         case NEGATE_EXPR:
 831         case BIT_NOT_EXPR:
 832           /* This is not correct for ABS_EXPR,
 833              since we must test the sign before truncation.  */
 834           {
 835             /* Do the arithmetic in type TYPEX,
 836                then convert result to TYPE.  */
 837             tree typex = type;
 838
 839             /* Can't do arithmetic in enumeral types
 840                so use an integer type that will hold the values.  */
 841             if (TREE_CODE (typex) == ENUMERAL_TYPE)
 842               typex
 843                 = lang_hooks.types.type_for_size (TYPE_PRECISION (typex),
 844                                                   TYPE_UNSIGNED (typex));
 845
 846             if (!TYPE_UNSIGNED (typex))
 847               typex = unsigned_type_for (typex);
 848             return convert (type,
 849                             fold_build1 (ex_form, typex,
 850                                          convert (typex,
 851                                                   TREE_OPERAND (expr, 0))));
 852           }
 853
 854         CASE_CONVERT:
 855           /* Don't introduce a
 856              "can't convert between vector values of different size" error.  */
 857           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 858               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 859                   != GET_MODE_SIZE (TYPE_MODE (type))))
 860             break;
 861           /* If truncating after truncating, might as well do all at once.
 862              If truncating after extending, we may get rid of wasted work.  */
 863           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 864
 865         case COND_EXPR:
 866           /* It is sometimes worthwhile to push the narrowing down through
 867              the conditional and never loses.  A COND_EXPR may have a throw
 868              as one operand, which then has void type.  Just leave void
 869              operands as they are.  */
 870           return fold_build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 871                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 1)))
 872                               ? TREE_OPERAND (expr, 1)
 873                               : convert (type, TREE_OPERAND (expr, 1)),
 874                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 2)))
 875                               ? TREE_OPERAND (expr, 2)
 876                               : convert (type, TREE_OPERAND (expr, 2)));
 877
 878         default:
 879           break;
 880         }
 881
 882       /* When parsing long initializers, we might end up with a lot of casts.
 883          Shortcut this.  */
 884       if (TREE_CODE (expr) == INTEGER_CST)
 885         return fold_convert (type, expr);
 886       return build1 (CONVERT_EXPR, type, expr);
 887
 888     case REAL_TYPE:
 889       if (flag_sanitize & SANITIZE_FLOAT_CAST
 890           && do_ubsan_in_current_function ())
 891         {
 892           expr = save_expr (expr);
 893           tree check = ubsan_instrument_float_cast (loc, type, expr, expr);
 894           expr = build1 (FIX_TRUNC_EXPR, type, expr);
 895           if (check == NULL)
 896             return expr;
 897           return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr);
 898         }
 899       else
 900         return build1 (FIX_TRUNC_EXPR, type, expr);
 901
 902     case FIXED_POINT_TYPE:
 903       return build1 (FIXED_CONVERT_EXPR, type, expr);
 904
 905     case COMPLEX_TYPE:
 906       return convert (type,
 907                       fold_build1 (REALPART_EXPR,
 908                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 909
 910     case VECTOR_TYPE:
 911       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 912         {
 913           error ("can%'t convert a vector of type %qT"
 914                  " to type %qT which has different size",
 915                  TREE_TYPE (expr), type);
 916           return error_mark_node;
 917         }
 918       return build1 (VIEW_CONVERT_EXPR, type, expr);
 919
 920     default:
 921       error ("aggregate value used where an integer was expected");
 922       return convert (type, integer_zero_node);
 923     }
 924 }
 925
 926 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 927
 928 tree
 929 convert_to_complex (tree type, tree expr)
 930 {
 931   tree subtype = TREE_TYPE (type);
 932
 933   switch (TREE_CODE (TREE_TYPE (expr)))
 934     {
 935     case REAL_TYPE:
 936     case FIXED_POINT_TYPE:
 937     case INTEGER_TYPE:
 938     case ENUMERAL_TYPE:
 939     case BOOLEAN_TYPE:
 940       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 941                      convert (subtype, integer_zero_node));
 942
 943     case COMPLEX_TYPE:
 944       {
 945         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 946
 947         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 948           return expr;
 949         else if (TREE_CODE (expr) == COMPOUND_EXPR)
 950           {
 951             tree t = convert_to_complex (type, TREE_OPERAND (expr, 1));
 952             if (t == TREE_OPERAND (expr, 1))
 953               return expr;
 954             return build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR,
 955                                TREE_TYPE (t), TREE_OPERAND (expr, 0), t);
 956           }
 957         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 958           return fold_build2 (COMPLEX_EXPR, type,
 959                               convert (subtype, TREE_OPERAND (expr, 0)),
 960                               convert (subtype, TREE_OPERAND (expr, 1)));
 961         else
 962           {
 963             expr = save_expr (expr);
 964             return
 965               fold_build2 (COMPLEX_EXPR, type,
 966                            convert (subtype,
 967                                     fold_build1 (REALPART_EXPR,
 968                                                  TREE_TYPE (TREE_TYPE (expr)),
 969                                                  expr)),
 970                            convert (subtype,
 971                                     fold_build1 (IMAGPART_EXPR,
 972                                                  TREE_TYPE (TREE_TYPE (expr)),
 973                                                  expr)));
 974           }
 975       }
 976
 977     case POINTER_TYPE:
 978     case REFERENCE_TYPE:
 979       error ("pointer value used where a complex was expected");
 980       return convert_to_complex (type, integer_zero_node);
 981
 982     default:
 983       error ("aggregate value used where a complex was expected");
 984       return convert_to_complex (type, integer_zero_node);
 985     }
 986 }
 987
 988 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 989
 990 tree
 991 convert_to_vector (tree type, tree expr)
 992 {
 993   switch (TREE_CODE (TREE_TYPE (expr)))
 994     {
 995     case INTEGER_TYPE:
 996     case VECTOR_TYPE:
 997       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 998         {
 999           error ("can%'t convert a value of type %qT"
1000                  " to vector type %qT which has different size",
1001                  TREE_TYPE (expr), type);
1002           return error_mark_node;
1003         }
1004       return build1 (VIEW_CONVERT_EXPR, type, expr);
1005
1006     default:
1007       error ("can%'t convert value to a vector");
1008       return error_mark_node;
1009     }
1010 }
1011
1012 /* Convert EXPR to some fixed-point type TYPE.
1013
1014    EXPR must be fixed-point, float, integer, or enumeral;
1015    in other cases error is called.  */
1016
1017 tree
1018 convert_to_fixed (tree type, tree expr)
1019 {
1020   if (integer_zerop (expr))
1021     {
1022       tree fixed_zero_node = build_fixed (type, FCONST0 (TYPE_MODE (type)));
1023       return fixed_zero_node;
1024     }
1025   else if (integer_onep (expr) && ALL_SCALAR_ACCUM_MODE_P (TYPE_MODE (type)))
1026     {
1027       tree fixed_one_node = build_fixed (type, FCONST1 (TYPE_MODE (type)));
1028       return fixed_one_node;
1029     }
1030
1031   switch (TREE_CODE (TREE_TYPE (expr)))
1032     {
1033     case FIXED_POINT_TYPE:
1034     case INTEGER_TYPE:
1035     case ENUMERAL_TYPE:
1036     case BOOLEAN_TYPE:
1037     case REAL_TYPE:
1038       return build1 (FIXED_CONVERT_EXPR, type, expr);
1039
1040     case COMPLEX_TYPE:
1041       return convert (type,
1042                       fold_build1 (REALPART_EXPR,
1043                                    TREE_TYPE (TREE_TYPE (expr)), expr));
1044
1045     default:
1046       error ("aggregate value used where a fixed-point was expected");
1047       return error_mark_node;
1048     }
1049 }