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 "hash-set.h"
  29 #include "machmode.h"
  30 #include "vec.h"
  31 #include "double-int.h"
  32 #include "input.h"
  33 #include "alias.h"
  34 #include "symtab.h"
  35 #include "wide-int.h"
  36 #include "inchash.h"
  37 #include "real.h"
  38 #include "fixed-value.h"
  39 #include "tree.h"
  40 #include "fold-const.h"
  41 #include "stor-layout.h"
  42 #include "flags.h"
  43 #include "convert.h"
  44 #include "diagnostic-core.h"
  45 #include "target.h"
  46 #include "langhooks.h"
  47 #include "builtins.h"
  48 #include "ubsan.h"
  49
  50 /* Convert EXPR to some pointer or reference type TYPE.
  51    EXPR must be pointer, reference, integer, enumeral, or literal zero;
  52    in other cases error is called.  */
  53
  54 tree
  55 convert_to_pointer (tree type, tree expr)
  56 {
  57   location_t loc = EXPR_LOCATION (expr);
  58   if (TREE_TYPE (expr) == type)
  59     return expr;
  60
  61   switch (TREE_CODE (TREE_TYPE (expr)))
  62     {
  63     case POINTER_TYPE:
  64     case REFERENCE_TYPE:
  65       {
  66         /* If the pointers point to different address spaces, conversion needs
  67            to be done via a ADDR_SPACE_CONVERT_EXPR instead of a NOP_EXPR.  */
  68         addr_space_t to_as = TYPE_ADDR_SPACE (TREE_TYPE (type));
  69         addr_space_t from_as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (expr)));
  70
  71         if (to_as == from_as)
  72           return fold_build1_loc (loc, NOP_EXPR, type, expr);
  73         else
  74           return fold_build1_loc (loc, ADDR_SPACE_CONVERT_EXPR, type, expr);
  75       }
  76
  77     case INTEGER_TYPE:
  78     case ENUMERAL_TYPE:
  79     case BOOLEAN_TYPE:
  80       {
  81         /* If the input precision differs from the target pointer type
  82            precision, first convert the input expression to an integer type of
  83            the target precision.  Some targets, e.g. VMS, need several pointer
  84            sizes to coexist so the latter isn't necessarily POINTER_SIZE.  */
  85         unsigned int pprec = TYPE_PRECISION (type);
  86         unsigned int eprec = TYPE_PRECISION (TREE_TYPE (expr));
  87
  88         if (eprec != pprec)
  89           expr = fold_build1_loc (loc, NOP_EXPR,
  90                               lang_hooks.types.type_for_size (pprec, 0),
  91                               expr);
  92       }
  93
  94       return fold_build1_loc (loc, CONVERT_EXPR, type, expr);
  95
  96     default:
  97       error ("cannot convert to a pointer type");
  98       return convert_to_pointer (type, integer_zero_node);
  99     }
 100 }
 101
 102
 103 /* Convert EXPR to some floating-point type TYPE.
 104
 105    EXPR must be float, fixed-point, integer, or enumeral;
 106    in other cases error is called.  */
 107
 108 tree
 109 convert_to_real (tree type, tree expr)
 110 {
 111   enum built_in_function fcode = builtin_mathfn_code (expr);
 112   tree itype = TREE_TYPE (expr);
 113
 114   if (TREE_CODE (expr) == COMPOUND_EXPR)
 115     {
 116       tree t = convert_to_real (type, TREE_OPERAND (expr, 1));
 117       if (t == TREE_OPERAND (expr, 1))
 118         return expr;
 119       return build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR, TREE_TYPE (t),
 120                          TREE_OPERAND (expr, 0), t);
 121     }
 122
 123   /* Disable until we figure out how to decide whether the functions are
 124      present in runtime.  */
 125   /* Convert (float)sqrt((double)x) where x is float into sqrtf(x) */
 126   if (optimize
 127       && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 128           || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 129     {
 130       switch (fcode)
 131         {
 132 #define CASE_MATHFN(FN) case BUILT_IN_##FN: case BUILT_IN_##FN##L:
 133           CASE_MATHFN (COSH)
 134           CASE_MATHFN (EXP)
 135           CASE_MATHFN (EXP10)
 136           CASE_MATHFN (EXP2)
 137           CASE_MATHFN (EXPM1)
 138           CASE_MATHFN (GAMMA)
 139           CASE_MATHFN (J0)
 140           CASE_MATHFN (J1)
 141           CASE_MATHFN (LGAMMA)
 142           CASE_MATHFN (POW10)
 143           CASE_MATHFN (SINH)
 144           CASE_MATHFN (TGAMMA)
 145           CASE_MATHFN (Y0)
 146           CASE_MATHFN (Y1)
 147             /* The above functions may set errno differently with float
 148                input or output so this transformation is not safe with
 149                -fmath-errno.  */
 150             if (flag_errno_math)
 151               break;
 152           CASE_MATHFN (ACOS)
 153           CASE_MATHFN (ACOSH)
 154           CASE_MATHFN (ASIN)
 155           CASE_MATHFN (ASINH)
 156           CASE_MATHFN (ATAN)
 157           CASE_MATHFN (ATANH)
 158           CASE_MATHFN (CBRT)
 159           CASE_MATHFN (COS)
 160           CASE_MATHFN (ERF)
 161           CASE_MATHFN (ERFC)
 162           CASE_MATHFN (LOG)
 163           CASE_MATHFN (LOG10)
 164           CASE_MATHFN (LOG2)
 165           CASE_MATHFN (LOG1P)
 166           CASE_MATHFN (SIN)
 167           CASE_MATHFN (TAN)
 168           CASE_MATHFN (TANH)
 169             /* The above functions are not safe to do this conversion.  */
 170             if (!flag_unsafe_math_optimizations)
 171               break;
 172           CASE_MATHFN (SQRT)
 173           CASE_MATHFN (FABS)
 174           CASE_MATHFN (LOGB)
 175 #undef CASE_MATHFN
 176             {
 177               tree arg0 = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 178               tree newtype = type;
 179
 180               /* We have (outertype)sqrt((innertype)x).  Choose the wider mode from
 181                  the both as the safe type for operation.  */
 182               if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (type))
 183                 newtype = TREE_TYPE (arg0);
 184
 185               /* We consider to convert
 186
 187                      (T1) sqrtT2 ((T2) exprT3)
 188                  to
 189                      (T1) sqrtT4 ((T4) exprT3)
 190
 191                   , where T1 is TYPE, T2 is ITYPE, T3 is TREE_TYPE (ARG0),
 192                  and T4 is NEWTYPE.  All those types are of floating point types.
 193                  T4 (NEWTYPE) should be narrower than T2 (ITYPE). This conversion
 194                  is safe only if P1 >= P2*2+2, where P1 and P2 are precisions of
 195                  T2 and T4.  See the following URL for a reference:
 196                  http://stackoverflow.com/questions/9235456/determining-
 197                  floating-point-square-root
 198                  */
 199               if ((fcode == BUILT_IN_SQRT || fcode == BUILT_IN_SQRTL)
 200                   && !flag_unsafe_math_optimizations)
 201                 {
 202                   /* The following conversion is unsafe even the precision condition
 203                      below is satisfied:
 204
 205                      (float) sqrtl ((long double) double_val) -> (float) sqrt (double_val)
 206                     */
 207                   if (TYPE_MODE (type) != TYPE_MODE (newtype))
 208                     break;
 209
 210                   int p1 = REAL_MODE_FORMAT (TYPE_MODE (itype))->p;
 211                   int p2 = REAL_MODE_FORMAT (TYPE_MODE (newtype))->p;
 212                   if (p1 < p2 * 2 + 2)
 213                     break;
 214                 }
 215
 216               /* Be careful about integer to fp conversions.
 217                  These may overflow still.  */
 218               if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 219                   && TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 220                   && (TYPE_MODE (newtype) == TYPE_MODE (double_type_node)
 221                       || TYPE_MODE (newtype) == TYPE_MODE (float_type_node)))
 222                 {
 223                   tree fn = mathfn_built_in (newtype, fcode);
 224
 225                   if (fn)
 226                   {
 227                     tree arg = fold (convert_to_real (newtype, arg0));
 228                     expr = build_call_expr (fn, 1, arg);
 229                     if (newtype == type)
 230                       return expr;
 231                   }
 232                 }
 233             }
 234         default:
 235           break;
 236         }
 237     }
 238   if (optimize
 239       && (((fcode == BUILT_IN_FLOORL
 240            || fcode == BUILT_IN_CEILL
 241            || fcode == BUILT_IN_ROUNDL
 242            || fcode == BUILT_IN_RINTL
 243            || fcode == BUILT_IN_TRUNCL
 244            || fcode == BUILT_IN_NEARBYINTL)
 245           && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
 246               || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
 247           || ((fcode == BUILT_IN_FLOOR
 248                || fcode == BUILT_IN_CEIL
 249                || fcode == BUILT_IN_ROUND
 250                || fcode == BUILT_IN_RINT
 251                || fcode == BUILT_IN_TRUNC
 252                || fcode == BUILT_IN_NEARBYINT)
 253               && (TYPE_MODE (type) == TYPE_MODE (float_type_node)))))
 254     {
 255       tree fn = mathfn_built_in (type, fcode);
 256
 257       if (fn)
 258         {
 259           tree arg = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
 260
 261           /* Make sure (type)arg0 is an extension, otherwise we could end up
 262              changing (float)floor(double d) into floorf((float)d), which is
 263              incorrect because (float)d uses round-to-nearest and can round
 264              up to the next integer.  */
 265           if (TYPE_PRECISION (type) >= TYPE_PRECISION (TREE_TYPE (arg)))
 266             return build_call_expr (fn, 1, fold (convert_to_real (type, arg)));
 267         }
 268     }
 269
 270   /* Propagate the cast into the operation.  */
 271   if (itype != type && FLOAT_TYPE_P (type))
 272     switch (TREE_CODE (expr))
 273       {
 274         /* Convert (float)-x into -(float)x.  This is safe for
 275            round-to-nearest rounding mode when the inner type is float.  */
 276         case ABS_EXPR:
 277         case NEGATE_EXPR:
 278           if (!flag_rounding_math
 279               && FLOAT_TYPE_P (itype)
 280               && TYPE_PRECISION (type) < TYPE_PRECISION (itype))
 281             return build1 (TREE_CODE (expr), type,
 282                            fold (convert_to_real (type,
 283                                                   TREE_OPERAND (expr, 0))));
 284           break;
 285         /* Convert (outertype)((innertype0)a+(innertype1)b)
 286            into ((newtype)a+(newtype)b) where newtype
 287            is the widest mode from all of these.  */
 288         case PLUS_EXPR:
 289         case MINUS_EXPR:
 290         case MULT_EXPR:
 291         case RDIV_EXPR:
 292            {
 293              tree arg0 = strip_float_extensions (TREE_OPERAND (expr, 0));
 294              tree arg1 = strip_float_extensions (TREE_OPERAND (expr, 1));
 295
 296              if (FLOAT_TYPE_P (TREE_TYPE (arg0))
 297                  && FLOAT_TYPE_P (TREE_TYPE (arg1))
 298                  && DECIMAL_FLOAT_TYPE_P (itype) == DECIMAL_FLOAT_TYPE_P (type))
 299                {
 300                   tree newtype = type;
 301
 302                   if (TYPE_MODE (TREE_TYPE (arg0)) == SDmode
 303                       || TYPE_MODE (TREE_TYPE (arg1)) == SDmode
 304                       || TYPE_MODE (type) == SDmode)
 305                     newtype = dfloat32_type_node;
 306                   if (TYPE_MODE (TREE_TYPE (arg0)) == DDmode
 307                       || TYPE_MODE (TREE_TYPE (arg1)) == DDmode
 308                       || TYPE_MODE (type) == DDmode)
 309                     newtype = dfloat64_type_node;
 310                   if (TYPE_MODE (TREE_TYPE (arg0)) == TDmode
 311                       || TYPE_MODE (TREE_TYPE (arg1)) == TDmode
 312                       || TYPE_MODE (type) == TDmode)
 313                     newtype = dfloat128_type_node;
 314                   if (newtype == dfloat32_type_node
 315                       || newtype == dfloat64_type_node
 316                       || newtype == dfloat128_type_node)
 317                     {
 318                       expr = build2 (TREE_CODE (expr), newtype,
 319                                      fold (convert_to_real (newtype, arg0)),
 320                                      fold (convert_to_real (newtype, arg1)));
 321                       if (newtype == type)
 322                         return expr;
 323                       break;
 324                     }
 325
 326                   if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (newtype))
 327                     newtype = TREE_TYPE (arg0);
 328                   if (TYPE_PRECISION (TREE_TYPE (arg1)) > TYPE_PRECISION (newtype))
 329                     newtype = TREE_TYPE (arg1);
 330                   /* Sometimes this transformation is safe (cannot
 331                      change results through affecting double rounding
 332                      cases) and sometimes it is not.  If NEWTYPE is
 333                      wider than TYPE, e.g. (float)((long double)double
 334                      + (long double)double) converted to
 335                      (float)(double + double), the transformation is
 336                      unsafe regardless of the details of the types
 337                      involved; double rounding can arise if the result
 338                      of NEWTYPE arithmetic is a NEWTYPE value half way
 339                      between two representable TYPE values but the
 340                      exact value is sufficiently different (in the
 341                      right direction) for this difference to be
 342                      visible in ITYPE arithmetic.  If NEWTYPE is the
 343                      same as TYPE, however, the transformation may be
 344                      safe depending on the types involved: it is safe
 345                      if the ITYPE has strictly more than twice as many
 346                      mantissa bits as TYPE, can represent infinities
 347                      and NaNs if the TYPE can, and has sufficient
 348                      exponent range for the product or ratio of two
 349                      values representable in the TYPE to be within the
 350                      range of normal values of ITYPE.  */
 351                   if (TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
 352                       && (flag_unsafe_math_optimizations
 353                           || (TYPE_PRECISION (newtype) == TYPE_PRECISION (type)
 354                               && real_can_shorten_arithmetic (TYPE_MODE (itype),
 355                                                               TYPE_MODE (type))
 356                               && !excess_precision_type (newtype))))
 357                     {
 358                       expr = build2 (TREE_CODE (expr), newtype,
 359                                      fold (convert_to_real (newtype, arg0)),
 360                                      fold (convert_to_real (newtype, arg1)));
 361                       if (newtype == type)
 362                         return expr;
 363                     }
 364                }
 365            }
 366           break;
 367         default:
 368           break;
 369       }
 370
 371   switch (TREE_CODE (TREE_TYPE (expr)))
 372     {
 373     case REAL_TYPE:
 374       /* Ignore the conversion if we don't need to store intermediate
 375          results and neither type is a decimal float.  */
 376       return build1 ((flag_float_store
 377                      || DECIMAL_FLOAT_TYPE_P (type)
 378                      || DECIMAL_FLOAT_TYPE_P (itype))
 379                      ? CONVERT_EXPR : NOP_EXPR, type, expr);
 380
 381     case INTEGER_TYPE:
 382     case ENUMERAL_TYPE:
 383     case BOOLEAN_TYPE:
 384       return build1 (FLOAT_EXPR, type, expr);
 385
 386     case FIXED_POINT_TYPE:
 387       return build1 (FIXED_CONVERT_EXPR, type, expr);
 388
 389     case COMPLEX_TYPE:
 390       return convert (type,
 391                       fold_build1 (REALPART_EXPR,
 392                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 393
 394     case POINTER_TYPE:
 395     case REFERENCE_TYPE:
 396       error ("pointer value used where a floating point value was expected");
 397       return convert_to_real (type, integer_zero_node);
 398
 399     default:
 400       error ("aggregate value used where a float was expected");
 401       return convert_to_real (type, integer_zero_node);
 402     }
 403 }
 404
 405 /* Convert EXPR to some integer (or enum) type TYPE.
 406
 407    EXPR must be pointer, integer, discrete (enum, char, or bool), float,
 408    fixed-point or vector; in other cases error is called.
 409
 410    The result of this is always supposed to be a newly created tree node
 411    not in use in any existing structure.  */
 412
 413 tree
 414 convert_to_integer (tree type, tree expr)
 415 {
 416   enum tree_code ex_form = TREE_CODE (expr);
 417   tree intype = TREE_TYPE (expr);
 418   unsigned int inprec = element_precision (intype);
 419   unsigned int outprec = element_precision (type);
 420   location_t loc = EXPR_LOCATION (expr);
 421
 422   /* An INTEGER_TYPE cannot be incomplete, but an ENUMERAL_TYPE can
 423      be.  Consider `enum E = { a, b = (enum E) 3 };'.  */
 424   if (!COMPLETE_TYPE_P (type))
 425     {
 426       error ("conversion to incomplete type");
 427       return error_mark_node;
 428     }
 429
 430   if (ex_form == COMPOUND_EXPR)
 431     {
 432       tree t = convert_to_integer (type, TREE_OPERAND (expr, 1));
 433       if (t == TREE_OPERAND (expr, 1))
 434         return expr;
 435       return build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR, TREE_TYPE (t),
 436                          TREE_OPERAND (expr, 0), t);
 437     }
 438
 439   /* Convert e.g. (long)round(d) -> lround(d).  */
 440   /* If we're converting to char, we may encounter differing behavior
 441      between converting from double->char vs double->long->char.
 442      We're in "undefined" territory but we prefer to be conservative,
 443      so only proceed in "unsafe" math mode.  */
 444   if (optimize
 445       && (flag_unsafe_math_optimizations
 446           || (long_integer_type_node
 447               && outprec >= TYPE_PRECISION (long_integer_type_node))))
 448     {
 449       tree s_expr = strip_float_extensions (expr);
 450       tree s_intype = TREE_TYPE (s_expr);
 451       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 452       tree fn = 0;
 453
 454       switch (fcode)
 455         {
 456         CASE_FLT_FN (BUILT_IN_CEIL):
 457           /* Only convert in ISO C99 mode.  */
 458           if (!targetm.libc_has_function (function_c99_misc))
 459             break;
 460           if (outprec < TYPE_PRECISION (integer_type_node)
 461               || (outprec == TYPE_PRECISION (integer_type_node)
 462                   && !TYPE_UNSIGNED (type)))
 463             fn = mathfn_built_in (s_intype, BUILT_IN_ICEIL);
 464           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 465                    && !TYPE_UNSIGNED (type))
 466             fn = mathfn_built_in (s_intype, BUILT_IN_LCEIL);
 467           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 468                    && !TYPE_UNSIGNED (type))
 469             fn = mathfn_built_in (s_intype, BUILT_IN_LLCEIL);
 470           break;
 471
 472         CASE_FLT_FN (BUILT_IN_FLOOR):
 473           /* Only convert in ISO C99 mode.  */
 474           if (!targetm.libc_has_function (function_c99_misc))
 475             break;
 476           if (outprec < TYPE_PRECISION (integer_type_node)
 477               || (outprec == TYPE_PRECISION (integer_type_node)
 478                   && !TYPE_UNSIGNED (type)))
 479             fn = mathfn_built_in (s_intype, BUILT_IN_IFLOOR);
 480           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 481                    && !TYPE_UNSIGNED (type))
 482             fn = mathfn_built_in (s_intype, BUILT_IN_LFLOOR);
 483           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 484                    && !TYPE_UNSIGNED (type))
 485             fn = mathfn_built_in (s_intype, BUILT_IN_LLFLOOR);
 486           break;
 487
 488         CASE_FLT_FN (BUILT_IN_ROUND):
 489           /* Only convert in ISO C99 mode and with -fno-math-errno.  */
 490           if (!targetm.libc_has_function (function_c99_misc) || flag_errno_math)
 491             break;
 492           if (outprec < TYPE_PRECISION (integer_type_node)
 493               || (outprec == TYPE_PRECISION (integer_type_node)
 494                   && !TYPE_UNSIGNED (type)))
 495             fn = mathfn_built_in (s_intype, BUILT_IN_IROUND);
 496           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 497                    && !TYPE_UNSIGNED (type))
 498             fn = mathfn_built_in (s_intype, BUILT_IN_LROUND);
 499           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 500                    && !TYPE_UNSIGNED (type))
 501             fn = mathfn_built_in (s_intype, BUILT_IN_LLROUND);
 502           break;
 503
 504         CASE_FLT_FN (BUILT_IN_NEARBYINT):
 505           /* Only convert nearbyint* if we can ignore math exceptions.  */
 506           if (flag_trapping_math)
 507             break;
 508           /* ... Fall through ...  */
 509         CASE_FLT_FN (BUILT_IN_RINT):
 510           /* Only convert in ISO C99 mode and with -fno-math-errno.  */
 511           if (!targetm.libc_has_function (function_c99_misc) || flag_errno_math)
 512             break;
 513           if (outprec < TYPE_PRECISION (integer_type_node)
 514               || (outprec == TYPE_PRECISION (integer_type_node)
 515                   && !TYPE_UNSIGNED (type)))
 516             fn = mathfn_built_in (s_intype, BUILT_IN_IRINT);
 517           else if (outprec == TYPE_PRECISION (long_integer_type_node)
 518                    && !TYPE_UNSIGNED (type))
 519             fn = mathfn_built_in (s_intype, BUILT_IN_LRINT);
 520           else if (outprec == TYPE_PRECISION (long_long_integer_type_node)
 521                    && !TYPE_UNSIGNED (type))
 522             fn = mathfn_built_in (s_intype, BUILT_IN_LLRINT);
 523           break;
 524
 525         CASE_FLT_FN (BUILT_IN_TRUNC):
 526           return convert_to_integer (type, CALL_EXPR_ARG (s_expr, 0));
 527
 528         default:
 529           break;
 530         }
 531
 532       if (fn)
 533         {
 534           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 535           return convert_to_integer (type, newexpr);
 536         }
 537     }
 538
 539   /* Convert (int)logb(d) -> ilogb(d).  */
 540   if (optimize
 541       && flag_unsafe_math_optimizations
 542       && !flag_trapping_math && !flag_errno_math && flag_finite_math_only
 543       && integer_type_node
 544       && (outprec > TYPE_PRECISION (integer_type_node)
 545           || (outprec == TYPE_PRECISION (integer_type_node)
 546               && !TYPE_UNSIGNED (type))))
 547     {
 548       tree s_expr = strip_float_extensions (expr);
 549       tree s_intype = TREE_TYPE (s_expr);
 550       const enum built_in_function fcode = builtin_mathfn_code (s_expr);
 551       tree fn = 0;
 552
 553       switch (fcode)
 554         {
 555         CASE_FLT_FN (BUILT_IN_LOGB):
 556           fn = mathfn_built_in (s_intype, BUILT_IN_ILOGB);
 557           break;
 558
 559         default:
 560           break;
 561         }
 562
 563       if (fn)
 564         {
 565           tree newexpr = build_call_expr (fn, 1, CALL_EXPR_ARG (s_expr, 0));
 566           return convert_to_integer (type, newexpr);
 567         }
 568     }
 569
 570   switch (TREE_CODE (intype))
 571     {
 572     case POINTER_TYPE:
 573     case REFERENCE_TYPE:
 574       if (integer_zerop (expr))
 575         return build_int_cst (type, 0);
 576
 577       /* Convert to an unsigned integer of the correct width first, and from
 578          there widen/truncate to the required type.  Some targets support the
 579          coexistence of multiple valid pointer sizes, so fetch the one we need
 580          from the type.  */
 581       expr = fold_build1 (CONVERT_EXPR,
 582                           lang_hooks.types.type_for_size
 583                             (TYPE_PRECISION (intype), 0),
 584                           expr);
 585       return fold_convert (type, expr);
 586
 587     case INTEGER_TYPE:
 588     case ENUMERAL_TYPE:
 589     case BOOLEAN_TYPE:
 590     case OFFSET_TYPE:
 591       /* If this is a logical operation, which just returns 0 or 1, we can
 592          change the type of the expression.  */
 593
 594       if (TREE_CODE_CLASS (ex_form) == tcc_comparison)
 595         {
 596           expr = copy_node (expr);
 597           TREE_TYPE (expr) = type;
 598           return expr;
 599         }
 600
 601       /* If we are widening the type, put in an explicit conversion.
 602          Similarly if we are not changing the width.  After this, we know
 603          we are truncating EXPR.  */
 604
 605       else if (outprec >= inprec)
 606         {
 607           enum tree_code code;
 608
 609           /* If the precision of the EXPR's type is K bits and the
 610              destination mode has more bits, and the sign is changing,
 611              it is not safe to use a NOP_EXPR.  For example, suppose
 612              that EXPR's type is a 3-bit unsigned integer type, the
 613              TYPE is a 3-bit signed integer type, and the machine mode
 614              for the types is 8-bit QImode.  In that case, the
 615              conversion necessitates an explicit sign-extension.  In
 616              the signed-to-unsigned case the high-order bits have to
 617              be cleared.  */
 618           if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (TREE_TYPE (expr))
 619               && (TYPE_PRECISION (TREE_TYPE (expr))
 620                   != GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (expr)))))
 621             code = CONVERT_EXPR;
 622           else
 623             code = NOP_EXPR;
 624
 625           return fold_build1 (code, type, expr);
 626         }
 627
 628       /* If TYPE is an enumeral type or a type with a precision less
 629          than the number of bits in its mode, do the conversion to the
 630          type corresponding to its mode, then do a nop conversion
 631          to TYPE.  */
 632       else if (TREE_CODE (type) == ENUMERAL_TYPE
 633                || outprec != GET_MODE_PRECISION (TYPE_MODE (type)))
 634         return build1 (NOP_EXPR, type,
 635                        convert (lang_hooks.types.type_for_mode
 636                                 (TYPE_MODE (type), TYPE_UNSIGNED (type)),
 637                                 expr));
 638
 639       /* Here detect when we can distribute the truncation down past some
 640          arithmetic.  For example, if adding two longs and converting to an
 641          int, we can equally well convert both to ints and then add.
 642          For the operations handled here, such truncation distribution
 643          is always safe.
 644          It is desirable in these cases:
 645          1) when truncating down to full-word from a larger size
 646          2) when truncating takes no work.
 647          3) when at least one operand of the arithmetic has been extended
 648          (as by C's default conversions).  In this case we need two conversions
 649          if we do the arithmetic as already requested, so we might as well
 650          truncate both and then combine.  Perhaps that way we need only one.
 651
 652          Note that in general we cannot do the arithmetic in a type
 653          shorter than the desired result of conversion, even if the operands
 654          are both extended from a shorter type, because they might overflow
 655          if combined in that type.  The exceptions to this--the times when
 656          two narrow values can be combined in their narrow type even to
 657          make a wider result--are handled by "shorten" in build_binary_op.  */
 658
 659       switch (ex_form)
 660         {
 661         case RSHIFT_EXPR:
 662           /* We can pass truncation down through right shifting
 663              when the shift count is a nonpositive constant.  */
 664           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 665               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) <= 0)
 666             goto trunc1;
 667           break;
 668
 669         case LSHIFT_EXPR:
 670           /* We can pass truncation down through left shifting
 671              when the shift count is a nonnegative constant and
 672              the target type is unsigned.  */
 673           if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
 674               && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
 675               && TYPE_UNSIGNED (type)
 676               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
 677             {
 678               /* If shift count is less than the width of the truncated type,
 679                  really shift.  */
 680               if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
 681                 /* In this case, shifting is like multiplication.  */
 682                 goto trunc1;
 683               else
 684                 {
 685                   /* If it is >= that width, result is zero.
 686                      Handling this with trunc1 would give the wrong result:
 687                      (int) ((long long) a << 32) is well defined (as 0)
 688                      but (int) a << 32 is undefined and would get a
 689                      warning.  */
 690
 691                   tree t = build_int_cst (type, 0);
 692
 693                   /* If the original expression had side-effects, we must
 694                      preserve it.  */
 695                   if (TREE_SIDE_EFFECTS (expr))
 696                     return build2 (COMPOUND_EXPR, type, expr, t);
 697                   else
 698                     return t;
 699                 }
 700             }
 701           break;
 702
 703         case TRUNC_DIV_EXPR:
 704           {
 705             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 706             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 707
 708             /* Don't distribute unless the output precision is at least as big
 709                as the actual inputs and it has the same signedness.  */
 710             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 711                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 712                 /* If signedness of arg0 and arg1 don't match,
 713                    we can't necessarily find a type to compare them in.  */
 714                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 715                     == TYPE_UNSIGNED (TREE_TYPE (arg1)))
 716                 /* Do not change the sign of the division.  */
 717                 && (TYPE_UNSIGNED (TREE_TYPE (expr))
 718                     == TYPE_UNSIGNED (TREE_TYPE (arg0)))
 719                 /* Either require unsigned division or a division by
 720                    a constant that is not -1.  */
 721                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 722                     || (TREE_CODE (arg1) == INTEGER_CST
 723                         && !integer_all_onesp (arg1))))
 724               goto trunc1;
 725             break;
 726           }
 727
 728         case MAX_EXPR:
 729         case MIN_EXPR:
 730         case MULT_EXPR:
 731           {
 732             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 733             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 734
 735             /* Don't distribute unless the output precision is at least as big
 736                as the actual inputs.  Otherwise, the comparison of the
 737                truncated values will be wrong.  */
 738             if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
 739                 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
 740                 /* If signedness of arg0 and arg1 don't match,
 741                    we can't necessarily find a type to compare them in.  */
 742                 && (TYPE_UNSIGNED (TREE_TYPE (arg0))
 743                     == TYPE_UNSIGNED (TREE_TYPE (arg1))))
 744               goto trunc1;
 745             break;
 746           }
 747
 748         case PLUS_EXPR:
 749         case MINUS_EXPR:
 750         case BIT_AND_EXPR:
 751         case BIT_IOR_EXPR:
 752         case BIT_XOR_EXPR:
 753         trunc1:
 754           {
 755             tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
 756             tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
 757
 758             /* Do not try to narrow operands of pointer subtraction;
 759                that will interfere with other folding.  */
 760             if (ex_form == MINUS_EXPR
 761                 && CONVERT_EXPR_P (arg0)
 762                 && CONVERT_EXPR_P (arg1)
 763                 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 0)))
 764                 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0))))
 765               break;
 766
 767             if (outprec >= BITS_PER_WORD
 768                 || TRULY_NOOP_TRUNCATION (outprec, inprec)
 769                 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
 770                 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
 771               {
 772                 /* Do the arithmetic in type TYPEX,
 773                    then convert result to TYPE.  */
 774                 tree typex = type;
 775
 776                 /* Can't do arithmetic in enumeral types
 777                    so use an integer type that will hold the values.  */
 778                 if (TREE_CODE (typex) == ENUMERAL_TYPE)
 779                   typex
 780                     = lang_hooks.types.type_for_size (TYPE_PRECISION (typex),
 781                                                       TYPE_UNSIGNED (typex));
 782
 783                 /* But now perhaps TYPEX is as wide as INPREC.
 784                    In that case, do nothing special here.
 785                    (Otherwise would recurse infinitely in convert.  */
 786                 if (TYPE_PRECISION (typex) != inprec)
 787                   {
 788                     /* Don't do unsigned arithmetic where signed was wanted,
 789                        or vice versa.
 790                        Exception: if both of the original operands were
 791                        unsigned then we can safely do the work as unsigned.
 792                        Exception: shift operations take their type solely
 793                        from the first argument.
 794                        Exception: the LSHIFT_EXPR case above requires that
 795                        we perform this operation unsigned lest we produce
 796                        signed-overflow undefinedness.
 797                        And we may need to do it as unsigned
 798                        if we truncate to the original size.  */
 799                     if (TYPE_UNSIGNED (TREE_TYPE (expr))
 800                         || (TYPE_UNSIGNED (TREE_TYPE (arg0))
 801                             && (TYPE_UNSIGNED (TREE_TYPE (arg1))
 802                                 || ex_form == LSHIFT_EXPR
 803                                 || ex_form == RSHIFT_EXPR
 804                                 || ex_form == LROTATE_EXPR
 805                                 || ex_form == RROTATE_EXPR))
 806                         || ex_form == LSHIFT_EXPR
 807                         /* If we have !flag_wrapv, and either ARG0 or
 808                            ARG1 is of a signed type, we have to do
 809                            PLUS_EXPR, MINUS_EXPR or MULT_EXPR in an unsigned
 810                            type in case the operation in outprec precision
 811                            could overflow.  Otherwise, we would introduce
 812                            signed-overflow undefinedness.  */
 813                         || ((!TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg0))
 814                              || !TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1)))
 815                             && ((TYPE_PRECISION (TREE_TYPE (arg0)) * 2u
 816                                  > outprec)
 817                                 || (TYPE_PRECISION (TREE_TYPE (arg1)) * 2u
 818                                     > outprec))
 819                             && (ex_form == PLUS_EXPR
 820                                 || ex_form == MINUS_EXPR
 821                                 || ex_form == MULT_EXPR)))
 822                       {
 823                         if (!TYPE_UNSIGNED (typex))
 824                           typex = unsigned_type_for (typex);
 825                       }
 826                     else
 827                       {
 828                         if (TYPE_UNSIGNED (typex))
 829                           typex = signed_type_for (typex);
 830                       }
 831                     return convert (type,
 832                                     fold_build2 (ex_form, typex,
 833                                                  convert (typex, arg0),
 834                                                  convert (typex, arg1)));
 835                   }
 836               }
 837           }
 838           break;
 839
 840         case NEGATE_EXPR:
 841         case BIT_NOT_EXPR:
 842           /* This is not correct for ABS_EXPR,
 843              since we must test the sign before truncation.  */
 844           {
 845             /* Do the arithmetic in type TYPEX,
 846                then convert result to TYPE.  */
 847             tree typex = type;
 848
 849             /* Can't do arithmetic in enumeral types
 850                so use an integer type that will hold the values.  */
 851             if (TREE_CODE (typex) == ENUMERAL_TYPE)
 852               typex
 853                 = lang_hooks.types.type_for_size (TYPE_PRECISION (typex),
 854                                                   TYPE_UNSIGNED (typex));
 855
 856             if (!TYPE_UNSIGNED (typex))
 857               typex = unsigned_type_for (typex);
 858             return convert (type,
 859                             fold_build1 (ex_form, typex,
 860                                          convert (typex,
 861                                                   TREE_OPERAND (expr, 0))));
 862           }
 863
 864         CASE_CONVERT:
 865           /* Don't introduce a
 866              "can't convert between vector values of different size" error.  */
 867           if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == VECTOR_TYPE
 868               && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0))))
 869                   != GET_MODE_SIZE (TYPE_MODE (type))))
 870             break;
 871           /* If truncating after truncating, might as well do all at once.
 872              If truncating after extending, we may get rid of wasted work.  */
 873           return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
 874
 875         case COND_EXPR:
 876           /* It is sometimes worthwhile to push the narrowing down through
 877              the conditional and never loses.  A COND_EXPR may have a throw
 878              as one operand, which then has void type.  Just leave void
 879              operands as they are.  */
 880           return fold_build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 881                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 1)))
 882                               ? TREE_OPERAND (expr, 1)
 883                               : convert (type, TREE_OPERAND (expr, 1)),
 884                               VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 2)))
 885                               ? TREE_OPERAND (expr, 2)
 886                               : convert (type, TREE_OPERAND (expr, 2)));
 887
 888         default:
 889           break;
 890         }
 891
 892       /* When parsing long initializers, we might end up with a lot of casts.
 893          Shortcut this.  */
 894       if (TREE_CODE (expr) == INTEGER_CST)
 895         return fold_convert (type, expr);
 896       return build1 (CONVERT_EXPR, type, expr);
 897
 898     case REAL_TYPE:
 899       if (flag_sanitize & SANITIZE_FLOAT_CAST
 900           && do_ubsan_in_current_function ())
 901         {
 902           expr = save_expr (expr);
 903           tree check = ubsan_instrument_float_cast (loc, type, expr, expr);
 904           expr = build1 (FIX_TRUNC_EXPR, type, expr);
 905           if (check == NULL)
 906             return expr;
 907           return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr);
 908         }
 909       else
 910         return build1 (FIX_TRUNC_EXPR, type, expr);
 911
 912     case FIXED_POINT_TYPE:
 913       return build1 (FIXED_CONVERT_EXPR, type, expr);
 914
 915     case COMPLEX_TYPE:
 916       return convert (type,
 917                       fold_build1 (REALPART_EXPR,
 918                                    TREE_TYPE (TREE_TYPE (expr)), expr));
 919
 920     case VECTOR_TYPE:
 921       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
 922         {
 923           error ("can%'t convert between vector values of different size");
 924           return error_mark_node;
 925         }
 926       return build1 (VIEW_CONVERT_EXPR, type, expr);
 927
 928     default:
 929       error ("aggregate value used where an integer was expected");
 930       return convert (type, integer_zero_node);
 931     }
 932 }
 933
 934 /* Convert EXPR to the complex type TYPE in the usual ways.  */
 935
 936 tree
 937 convert_to_complex (tree type, tree expr)
 938 {
 939   tree subtype = TREE_TYPE (type);
 940
 941   switch (TREE_CODE (TREE_TYPE (expr)))
 942     {
 943     case REAL_TYPE:
 944     case FIXED_POINT_TYPE:
 945     case INTEGER_TYPE:
 946     case ENUMERAL_TYPE:
 947     case BOOLEAN_TYPE:
 948       return build2 (COMPLEX_EXPR, type, convert (subtype, expr),
 949                      convert (subtype, integer_zero_node));
 950
 951     case COMPLEX_TYPE:
 952       {
 953         tree elt_type = TREE_TYPE (TREE_TYPE (expr));
 954
 955         if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
 956           return expr;
 957         else if (TREE_CODE (expr) == COMPOUND_EXPR)
 958           {
 959             tree t = convert_to_complex (type, TREE_OPERAND (expr, 1));
 960             if (t == TREE_OPERAND (expr, 1))
 961               return expr;
 962             return build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR,
 963                                TREE_TYPE (t), TREE_OPERAND (expr, 0), t);
 964           }
 965         else if (TREE_CODE (expr) == COMPLEX_EXPR)
 966           return fold_build2 (COMPLEX_EXPR, type,
 967                               convert (subtype, TREE_OPERAND (expr, 0)),
 968                               convert (subtype, TREE_OPERAND (expr, 1)));
 969         else
 970           {
 971             expr = save_expr (expr);
 972             return
 973               fold_build2 (COMPLEX_EXPR, type,
 974                            convert (subtype,
 975                                     fold_build1 (REALPART_EXPR,
 976                                                  TREE_TYPE (TREE_TYPE (expr)),
 977                                                  expr)),
 978                            convert (subtype,
 979                                     fold_build1 (IMAGPART_EXPR,
 980                                                  TREE_TYPE (TREE_TYPE (expr)),
 981                                                  expr)));
 982           }
 983       }
 984
 985     case POINTER_TYPE:
 986     case REFERENCE_TYPE:
 987       error ("pointer value used where a complex was expected");
 988       return convert_to_complex (type, integer_zero_node);
 989
 990     default:
 991       error ("aggregate value used where a complex was expected");
 992       return convert_to_complex (type, integer_zero_node);
 993     }
 994 }
 995
 996 /* Convert EXPR to the vector type TYPE in the usual ways.  */
 997
 998 tree
 999 convert_to_vector (tree type, tree expr)
1000 {
1001   switch (TREE_CODE (TREE_TYPE (expr)))
1002     {
1003     case INTEGER_TYPE:
1004     case VECTOR_TYPE:
1005       if (!tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (expr))))
1006         {
1007           error ("can%'t convert between vector values of different size");
1008           return error_mark_node;
1009         }
1010       return build1 (VIEW_CONVERT_EXPR, type, expr);
1011
1012     default:
1013       error ("can%'t convert value to a vector");
1014       return error_mark_node;
1015     }
1016 }
1017
1018 /* Convert EXPR to some fixed-point type TYPE.
1019
1020    EXPR must be fixed-point, float, integer, or enumeral;
1021    in other cases error is called.  */
1022
1023 tree
1024 convert_to_fixed (tree type, tree expr)
1025 {
1026   if (integer_zerop (expr))
1027     {
1028       tree fixed_zero_node = build_fixed (type, FCONST0 (TYPE_MODE (type)));
1029       return fixed_zero_node;
1030     }
1031   else if (integer_onep (expr) && ALL_SCALAR_ACCUM_MODE_P (TYPE_MODE (type)))
1032     {
1033       tree fixed_one_node = build_fixed (type, FCONST1 (TYPE_MODE (type)));
1034       return fixed_one_node;
1035     }
1036
1037   switch (TREE_CODE (TREE_TYPE (expr)))
1038     {
1039     case FIXED_POINT_TYPE:
1040     case INTEGER_TYPE:
1041     case ENUMERAL_TYPE:
1042     case BOOLEAN_TYPE:
1043     case REAL_TYPE:
1044       return build1 (FIXED_CONVERT_EXPR, type, expr);
1045
1046     case COMPLEX_TYPE:
1047       return convert (type,
1048                       fold_build1 (REALPART_EXPR,
1049                                    TREE_TYPE (TREE_TYPE (expr)), expr));
1050
1051     default:
1052       error ("aggregate value used where a fixed-point was expected");
1053       return error_mark_node;
1054     }
1055 }