gcc/dojump.c

   1 /* Convert tree expression to rtl instructions, for GNU compiler.
   2    Copyright (C) 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
   3    2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "rtl.h"
  27 #include "tree.h"
  28 #include "flags.h"
  29 #include "function.h"
  30 #include "insn-config.h"
  31 #include "insn-attr.h"
  32 /* Include expr.h after insn-config.h so we get HAVE_conditional_move.  */
  33 #include "expr.h"
  34 #include "optabs.h"
  35 #include "langhooks.h"
  36 #include "ggc.h"
  37
  38 static bool prefer_and_bit_test (enum machine_mode, int);
  39 static void do_jump_by_parts_greater (tree, int, rtx, rtx);
  40 static void do_jump_by_parts_equality (tree, rtx, rtx);
  41 static void do_compare_and_jump (tree, enum rtx_code, enum rtx_code, rtx,
  42                                  rtx);
  43
  44 /* At the start of a function, record that we have no previously-pushed
  45    arguments waiting to be popped.  */
  46
  47 void
  48 init_pending_stack_adjust (void)
  49 {
  50   pending_stack_adjust = 0;
  51 }
  52
  53 /* Discard any pending stack adjustment.  This avoid relying on the
  54    RTL optimizers to remove useless adjustments when we know the
  55    stack pointer value is dead.  */
  56 void discard_pending_stack_adjust (void)
  57 {
  58   stack_pointer_delta -= pending_stack_adjust;
  59   pending_stack_adjust = 0;
  60 }
  61
  62 /* When exiting from function, if safe, clear out any pending stack adjust
  63    so the adjustment won't get done.
  64
  65    Note, if the current function calls alloca, then it must have a
  66    frame pointer regardless of the value of flag_omit_frame_pointer.  */
  67
  68 void
  69 clear_pending_stack_adjust (void)
  70 {
  71   if (optimize > 0
  72       && (! flag_omit_frame_pointer || current_function_calls_alloca)
  73       && EXIT_IGNORE_STACK
  74       && ! (DECL_INLINE (current_function_decl) && ! flag_no_inline))
  75     discard_pending_stack_adjust ();
  76 }
  77
  78 /* Pop any previously-pushed arguments that have not been popped yet.  */
  79
  80 void
  81 do_pending_stack_adjust (void)
  82 {
  83   if (inhibit_defer_pop == 0)
  84     {
  85       if (pending_stack_adjust != 0)
  86         adjust_stack (GEN_INT (pending_stack_adjust));
  87       pending_stack_adjust = 0;
  88     }
  89 }
  90 \f
  91 /* Expand conditional expressions.  */
  92
  93 /* Generate code to evaluate EXP and jump to LABEL if the value is zero.
  94    LABEL is an rtx of code CODE_LABEL, in this function and all the
  95    functions here.  */
  96
  97 void
  98 jumpifnot (tree exp, rtx label)
  99 {
 100   do_jump (exp, label, NULL_RTX);
 101 }
 102
 103 /* Generate code to evaluate EXP and jump to LABEL if the value is nonzero.  */
 104
 105 void
 106 jumpif (tree exp, rtx label)
 107 {
 108   do_jump (exp, NULL_RTX, label);
 109 }
 110
 111 /* Used internally by prefer_and_bit_test.  */
 112
 113 static GTY(()) rtx and_reg;
 114 static GTY(()) rtx and_test;
 115 static GTY(()) rtx shift_test;
 116
 117 /* Compare the relative costs of "(X & (1 << BITNUM))" and "(X >> BITNUM) & 1",
 118    where X is an arbitrary register of mode MODE.  Return true if the former
 119    is preferred.  */
 120
 121 static bool
 122 prefer_and_bit_test (enum machine_mode mode, int bitnum)
 123 {
 124   if (and_test == 0)
 125     {
 126       /* Set up rtxes for the two variations.  Use NULL as a placeholder
 127          for the BITNUM-based constants.  */
 128       and_reg = gen_rtx_REG (mode, FIRST_PSEUDO_REGISTER);
 129       and_test = gen_rtx_AND (mode, and_reg, NULL);
 130       shift_test = gen_rtx_AND (mode, gen_rtx_ASHIFTRT (mode, and_reg, NULL),
 131                                 const1_rtx);
 132     }
 133   else
 134     {
 135       /* Change the mode of the previously-created rtxes.  */
 136       PUT_MODE (and_reg, mode);
 137       PUT_MODE (and_test, mode);
 138       PUT_MODE (shift_test, mode);
 139       PUT_MODE (XEXP (shift_test, 0), mode);
 140     }
 141
 142   /* Fill in the integers.  */
 143   XEXP (and_test, 1) = GEN_INT ((unsigned HOST_WIDE_INT) 1 << bitnum);
 144   XEXP (XEXP (shift_test, 0), 1) = GEN_INT (bitnum);
 145
 146   return (rtx_cost (and_test, IF_THEN_ELSE)
 147           <= rtx_cost (shift_test, IF_THEN_ELSE));
 148 }
 149
 150 /* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if
 151    the result is zero, or IF_TRUE_LABEL if the result is one.
 152    Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero,
 153    meaning fall through in that case.
 154
 155    do_jump always does any pending stack adjust except when it does not
 156    actually perform a jump.  An example where there is no jump
 157    is when EXP is `(foo (), 0)' and IF_FALSE_LABEL is null.  */
 158
 159 void
 160 do_jump (tree exp, rtx if_false_label, rtx if_true_label)
 161 {
 162   enum tree_code code = TREE_CODE (exp);
 163   rtx temp;
 164   int i;
 165   tree type;
 166   enum machine_mode mode;
 167   rtx drop_through_label = 0;
 168
 169   switch (code)
 170     {
 171     case ERROR_MARK:
 172       break;
 173
 174     case INTEGER_CST:
 175       temp = integer_zerop (exp) ? if_false_label : if_true_label;
 176       if (temp)
 177         emit_jump (temp);
 178       break;
 179
 180 #if 0
 181       /* This is not true with #pragma weak  */
 182     case ADDR_EXPR:
 183       /* The address of something can never be zero.  */
 184       if (if_true_label)
 185         emit_jump (if_true_label);
 186       break;
 187 #endif
 188
 189     case NOP_EXPR:
 190       if (TREE_CODE (TREE_OPERAND (exp, 0)) == COMPONENT_REF
 191           || TREE_CODE (TREE_OPERAND (exp, 0)) == BIT_FIELD_REF
 192           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF
 193           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_RANGE_REF)
 194         goto normal;
 195     case CONVERT_EXPR:
 196       /* If we are narrowing the operand, we have to do the compare in the
 197          narrower mode.  */
 198       if ((TYPE_PRECISION (TREE_TYPE (exp))
 199            < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
 200         goto normal;
 201     case NON_LVALUE_EXPR:
 202     case ABS_EXPR:
 203     case NEGATE_EXPR:
 204     case LROTATE_EXPR:
 205     case RROTATE_EXPR:
 206       /* These cannot change zero->nonzero or vice versa.  */
 207       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 208       break;
 209
 210     case BIT_AND_EXPR:
 211       /* fold_single_bit_test() converts (X & (1 << C)) into (X >> C) & 1.
 212          See if the former is preferred for jump tests and restore it
 213          if so.  */
 214       if (integer_onep (TREE_OPERAND (exp, 1)))
 215         {
 216           tree exp0 = TREE_OPERAND (exp, 0);
 217           rtx set_label, clr_label;
 218
 219           /* Strip narrowing integral type conversions.  */
 220           while ((TREE_CODE (exp0) == NOP_EXPR
 221                   || TREE_CODE (exp0) == CONVERT_EXPR
 222                   || TREE_CODE (exp0) == NON_LVALUE_EXPR)
 223                  && TREE_OPERAND (exp0, 0) != error_mark_node
 224                  && TYPE_PRECISION (TREE_TYPE (exp0))
 225                     <= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp0, 0))))
 226             exp0 = TREE_OPERAND (exp0, 0);
 227
 228           /* "exp0 ^ 1" inverts the sense of the single bit test.  */
 229           if (TREE_CODE (exp0) == BIT_XOR_EXPR
 230               && integer_onep (TREE_OPERAND (exp0, 1)))
 231             {
 232               exp0 = TREE_OPERAND (exp0, 0);
 233               clr_label = if_true_label;
 234               set_label = if_false_label;
 235             }
 236           else
 237             {
 238               clr_label = if_false_label;
 239               set_label = if_true_label;
 240             }
 241
 242           if (TREE_CODE (exp0) == RSHIFT_EXPR)
 243             {
 244               tree arg = TREE_OPERAND (exp0, 0);
 245               tree shift = TREE_OPERAND (exp0, 1);
 246               tree argtype = TREE_TYPE (arg);
 247               if (TREE_CODE (shift) == INTEGER_CST
 248                   && compare_tree_int (shift, 0) >= 0
 249                   && compare_tree_int (shift, HOST_BITS_PER_WIDE_INT) < 0
 250                   && prefer_and_bit_test (TYPE_MODE (argtype),
 251                                           TREE_INT_CST_LOW (shift)))
 252                 {
 253                   HOST_WIDE_INT mask = (HOST_WIDE_INT) 1
 254                                        << TREE_INT_CST_LOW (shift);
 255                   do_jump (build2 (BIT_AND_EXPR, argtype, arg,
 256                                    build_int_cst_type (argtype, mask)),
 257                            clr_label, set_label);
 258                   break;
 259                 }
 260             }
 261         }
 262
 263       /* If we are AND'ing with a small constant, do this comparison in the
 264          smallest type that fits.  If the machine doesn't have comparisons
 265          that small, it will be converted back to the wider comparison.
 266          This helps if we are testing the sign bit of a narrower object.
 267          combine can't do this for us because it can't know whether a
 268          ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */
 269
 270       if (! SLOW_BYTE_ACCESS
 271           && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
 272           && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT
 273           && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0
 274           && (mode = mode_for_size (i + 1, MODE_INT, 0)) != BLKmode
 275           && (type = lang_hooks.types.type_for_mode (mode, 1)) != 0
 276           && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 277           && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 278               != CODE_FOR_nothing))
 279         {
 280           do_jump (convert (type, exp), if_false_label, if_true_label);
 281           break;
 282         }
 283       goto normal;
 284
 285     case TRUTH_NOT_EXPR:
 286       do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 287       break;
 288
 289     case COND_EXPR:
 290       {
 291         rtx label1 = gen_label_rtx ();
 292         if (!if_true_label || !if_false_label)
 293           {
 294             drop_through_label = gen_label_rtx ();
 295             if (!if_true_label)
 296               if_true_label = drop_through_label;
 297             if (!if_false_label)
 298               if_false_label = drop_through_label;
 299           }
 300
 301         do_pending_stack_adjust ();
 302         do_jump (TREE_OPERAND (exp, 0), label1, NULL_RTX);
 303         do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 304         emit_label (label1);
 305         do_jump (TREE_OPERAND (exp, 2), if_false_label, if_true_label);
 306         break;
 307       }
 308
 309     case TRUTH_ANDIF_EXPR:
 310     case TRUTH_ORIF_EXPR:
 311     case COMPOUND_EXPR:
 312       /* Lowered by gimplify.c.  */
 313       gcc_unreachable ();
 314
 315     case COMPONENT_REF:
 316     case BIT_FIELD_REF:
 317     case ARRAY_REF:
 318     case ARRAY_RANGE_REF:
 319       {
 320         HOST_WIDE_INT bitsize, bitpos;
 321         int unsignedp;
 322         enum machine_mode mode;
 323         tree type;
 324         tree offset;
 325         int volatilep = 0;
 326
 327         /* Get description of this reference.  We don't actually care
 328            about the underlying object here.  */
 329         get_inner_reference (exp, &bitsize, &bitpos, &offset, &mode,
 330                              &unsignedp, &volatilep, false);
 331
 332         type = lang_hooks.types.type_for_size (bitsize, unsignedp);
 333         if (! SLOW_BYTE_ACCESS
 334             && type != 0 && bitsize >= 0
 335             && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 336             && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 337                 != CODE_FOR_nothing))
 338           {
 339             do_jump (convert (type, exp), if_false_label, if_true_label);
 340             break;
 341           }
 342         goto normal;
 343       }
 344
 345     case EQ_EXPR:
 346       {
 347         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 348
 349         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 350                     != MODE_COMPLEX_FLOAT);
 351         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 352                     != MODE_COMPLEX_INT);
 353
 354         if (integer_zerop (TREE_OPERAND (exp, 1)))
 355           do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 356         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 357                  && !can_compare_p (EQ, TYPE_MODE (inner_type), ccp_jump))
 358           do_jump_by_parts_equality (exp, if_false_label, if_true_label);
 359         else
 360           do_compare_and_jump (exp, EQ, EQ, if_false_label, if_true_label);
 361         break;
 362       }
 363
 364     case MINUS_EXPR:
 365       /* Nonzero iff operands of minus differ.  */
 366       exp = build2 (NE_EXPR, TREE_TYPE (exp),
 367                     TREE_OPERAND (exp, 0),
 368                     TREE_OPERAND (exp, 1));
 369       /* FALLTHRU */
 370     case NE_EXPR:
 371       {
 372         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 373
 374         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 375                     != MODE_COMPLEX_FLOAT);
 376         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 377                     != MODE_COMPLEX_INT);
 378
 379         if (integer_zerop (TREE_OPERAND (exp, 1)))
 380           do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 381         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 382            && !can_compare_p (NE, TYPE_MODE (inner_type), ccp_jump))
 383           do_jump_by_parts_equality (exp, if_true_label, if_false_label);
 384         else
 385           do_compare_and_jump (exp, NE, NE, if_false_label, if_true_label);
 386         break;
 387       }
 388
 389     case LT_EXPR:
 390       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 391       if (GET_MODE_CLASS (mode) == MODE_INT
 392           && ! can_compare_p (LT, mode, ccp_jump))
 393         do_jump_by_parts_greater (exp, 1, if_false_label, if_true_label);
 394       else
 395         do_compare_and_jump (exp, LT, LTU, if_false_label, if_true_label);
 396       break;
 397
 398     case LE_EXPR:
 399       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 400       if (GET_MODE_CLASS (mode) == MODE_INT
 401           && ! can_compare_p (LE, mode, ccp_jump))
 402         do_jump_by_parts_greater (exp, 0, if_true_label, if_false_label);
 403       else
 404         do_compare_and_jump (exp, LE, LEU, if_false_label, if_true_label);
 405       break;
 406
 407     case GT_EXPR:
 408       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 409       if (GET_MODE_CLASS (mode) == MODE_INT
 410           && ! can_compare_p (GT, mode, ccp_jump))
 411         do_jump_by_parts_greater (exp, 0, if_false_label, if_true_label);
 412       else
 413         do_compare_and_jump (exp, GT, GTU, if_false_label, if_true_label);
 414       break;
 415
 416     case GE_EXPR:
 417       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 418       if (GET_MODE_CLASS (mode) == MODE_INT
 419           && ! can_compare_p (GE, mode, ccp_jump))
 420         do_jump_by_parts_greater (exp, 1, if_true_label, if_false_label);
 421       else
 422         do_compare_and_jump (exp, GE, GEU, if_false_label, if_true_label);
 423       break;
 424
 425     case UNORDERED_EXPR:
 426     case ORDERED_EXPR:
 427       {
 428         enum rtx_code cmp, rcmp;
 429         int do_rev;
 430
 431         if (code == UNORDERED_EXPR)
 432           cmp = UNORDERED, rcmp = ORDERED;
 433         else
 434           cmp = ORDERED, rcmp = UNORDERED;
 435         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 436
 437         do_rev = 0;
 438         if (! can_compare_p (cmp, mode, ccp_jump)
 439             && (can_compare_p (rcmp, mode, ccp_jump)
 440           /* If the target doesn't provide either UNORDERED or ORDERED
 441              comparisons, canonicalize on UNORDERED for the library.  */
 442           || rcmp == UNORDERED))
 443           do_rev = 1;
 444
 445         if (! do_rev)
 446           do_compare_and_jump (exp, cmp, cmp, if_false_label, if_true_label);
 447         else
 448           do_compare_and_jump (exp, rcmp, rcmp, if_true_label, if_false_label);
 449       }
 450       break;
 451
 452     {
 453       enum rtx_code rcode1;
 454       enum tree_code tcode1, tcode2;
 455
 456       case UNLT_EXPR:
 457         rcode1 = UNLT;
 458         tcode1 = UNORDERED_EXPR;
 459         tcode2 = LT_EXPR;
 460         goto unordered_bcc;
 461       case UNLE_EXPR:
 462         rcode1 = UNLE;
 463         tcode1 = UNORDERED_EXPR;
 464         tcode2 = LE_EXPR;
 465         goto unordered_bcc;
 466       case UNGT_EXPR:
 467         rcode1 = UNGT;
 468         tcode1 = UNORDERED_EXPR;
 469         tcode2 = GT_EXPR;
 470         goto unordered_bcc;
 471       case UNGE_EXPR:
 472         rcode1 = UNGE;
 473         tcode1 = UNORDERED_EXPR;
 474         tcode2 = GE_EXPR;
 475         goto unordered_bcc;
 476       case UNEQ_EXPR:
 477         rcode1 = UNEQ;
 478         tcode1 = UNORDERED_EXPR;
 479         tcode2 = EQ_EXPR;
 480         goto unordered_bcc;
 481       case LTGT_EXPR:
 482         /* It is ok for LTGT_EXPR to trap when the result is unordered,
 483            so expand to (a < b) || (a > b).  */
 484         rcode1 = LTGT;
 485         tcode1 = LT_EXPR;
 486         tcode2 = GT_EXPR;
 487         goto unordered_bcc;
 488
 489       unordered_bcc:
 490         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 491         if (can_compare_p (rcode1, mode, ccp_jump))
 492           do_compare_and_jump (exp, rcode1, rcode1, if_false_label,
 493                                if_true_label);
 494         else
 495           {
 496             tree op0 = save_expr (TREE_OPERAND (exp, 0));
 497             tree op1 = save_expr (TREE_OPERAND (exp, 1));
 498             tree cmp0, cmp1;
 499
 500             /* If the target doesn't support combined unordered
 501                compares, decompose into two comparisons.  */
 502             if (if_true_label == 0)
 503               drop_through_label = if_true_label = gen_label_rtx ();
 504
 505             cmp0 = fold_build2 (tcode1, TREE_TYPE (exp), op0, op1);
 506             cmp1 = fold_build2 (tcode2, TREE_TYPE (exp), op0, op1);
 507             do_jump (cmp0, 0, if_true_label);
 508             do_jump (cmp1, if_false_label, if_true_label);
 509           }
 510       }
 511       break;
 512
 513       /* Special case:
 514           __builtin_expect (<test>, 0)  and
 515           __builtin_expect (<test>, 1)
 516
 517          We need to do this here, so that <test> is not converted to a SCC
 518          operation on machines that use condition code registers and COMPARE
 519          like the PowerPC, and then the jump is done based on whether the SCC
 520          operation produced a 1 or 0.  */
 521     case CALL_EXPR:
 522       /* Check for a built-in function.  */
 523       {
 524         tree fndecl = get_callee_fndecl (exp);
 525         tree arglist = TREE_OPERAND (exp, 1);
 526
 527         if (fndecl
 528             && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
 529             && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT
 530             && arglist != NULL_TREE
 531             && TREE_CHAIN (arglist) != NULL_TREE)
 532           {
 533             rtx seq = expand_builtin_expect_jump (exp, if_false_label,
 534                                                   if_true_label);
 535
 536             if (seq != NULL_RTX)
 537               {
 538                 emit_insn (seq);
 539                 return;
 540               }
 541           }
 542       }
 543       /* Fall through and generate the normal code.  */
 544
 545     default:
 546     normal:
 547       temp = expand_expr (exp, NULL_RTX, VOIDmode, 0);
 548       do_pending_stack_adjust ();
 549
 550       if (GET_CODE (temp) == CONST_INT
 551           || (GET_CODE (temp) == CONST_DOUBLE && GET_MODE (temp) == VOIDmode)
 552           || GET_CODE (temp) == LABEL_REF)
 553         {
 554           rtx target = temp == const0_rtx ? if_false_label : if_true_label;
 555           if (target)
 556             emit_jump (target);
 557         }
 558       else if (GET_MODE_CLASS (GET_MODE (temp)) == MODE_INT
 559                && ! can_compare_p (NE, GET_MODE (temp), ccp_jump))
 560         /* Note swapping the labels gives us not-equal.  */
 561         do_jump_by_parts_equality_rtx (temp, if_true_label, if_false_label);
 562       else
 563         {
 564           gcc_assert (GET_MODE (temp) != VOIDmode);
 565
 566           /* The RTL optimizers prefer comparisons against pseudos.  */
 567           if (GET_CODE (temp) == SUBREG)
 568             {
 569               /* Compare promoted variables in their promoted mode.  */
 570               if (SUBREG_PROMOTED_VAR_P (temp)
 571                   && REG_P (XEXP (temp, 0)))
 572                 temp = XEXP (temp, 0);
 573               else
 574                 temp = copy_to_reg (temp);
 575             }
 576           do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),
 577                                    NE, TYPE_UNSIGNED (TREE_TYPE (exp)),
 578                                    GET_MODE (temp), NULL_RTX,
 579                                    if_false_label, if_true_label);
 580         }
 581     }
 582
 583   if (drop_through_label)
 584     {
 585       do_pending_stack_adjust ();
 586       emit_label (drop_through_label);
 587     }
 588 }
 589 \f
 590 /* Given a comparison expression EXP for values too wide to be compared
 591    with one insn, test the comparison and jump to the appropriate label.
 592    The code of EXP is ignored; we always test GT if SWAP is 0,
 593    and LT if SWAP is 1.  */
 594
 595 static void
 596 do_jump_by_parts_greater (tree exp, int swap, rtx if_false_label,
 597                           rtx if_true_label)
 598 {
 599   rtx op0 = expand_expr (TREE_OPERAND (exp, swap), NULL_RTX, VOIDmode, 0);
 600   rtx op1 = expand_expr (TREE_OPERAND (exp, !swap), NULL_RTX, VOIDmode, 0);
 601   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 602   int unsignedp = TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)));
 603
 604   do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label,
 605                                 if_true_label);
 606 }
 607
 608 /* Compare OP0 with OP1, word at a time, in mode MODE.
 609    UNSIGNEDP says to do unsigned comparison.
 610    Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */
 611
 612 void
 613 do_jump_by_parts_greater_rtx (enum machine_mode mode, int unsignedp, rtx op0,
 614                               rtx op1, rtx if_false_label, rtx if_true_label)
 615 {
 616   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 617   rtx drop_through_label = 0;
 618   int i;
 619
 620   if (! if_true_label || ! if_false_label)
 621     drop_through_label = gen_label_rtx ();
 622   if (! if_true_label)
 623     if_true_label = drop_through_label;
 624   if (! if_false_label)
 625     if_false_label = drop_through_label;
 626
 627   /* Compare a word at a time, high order first.  */
 628   for (i = 0; i < nwords; i++)
 629     {
 630       rtx op0_word, op1_word;
 631
 632       if (WORDS_BIG_ENDIAN)
 633         {
 634           op0_word = operand_subword_force (op0, i, mode);
 635           op1_word = operand_subword_force (op1, i, mode);
 636         }
 637       else
 638         {
 639           op0_word = operand_subword_force (op0, nwords - 1 - i, mode);
 640           op1_word = operand_subword_force (op1, nwords - 1 - i, mode);
 641         }
 642
 643       /* All but high-order word must be compared as unsigned.  */
 644       do_compare_rtx_and_jump (op0_word, op1_word, GT,
 645                                (unsignedp || i > 0), word_mode, NULL_RTX,
 646                                NULL_RTX, if_true_label);
 647
 648       /* Consider lower words only if these are equal.  */
 649       do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,
 650                                NULL_RTX, NULL_RTX, if_false_label);
 651     }
 652
 653   if (if_false_label)
 654     emit_jump (if_false_label);
 655   if (drop_through_label)
 656     emit_label (drop_through_label);
 657 }
 658
 659 /* Given an EQ_EXPR expression EXP for values too wide to be compared
 660    with one insn, test the comparison and jump to the appropriate label.  */
 661
 662 static void
 663 do_jump_by_parts_equality (tree exp, rtx if_false_label, rtx if_true_label)
 664 {
 665   rtx op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
 666   rtx op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 667   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 668   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 669   int i;
 670   rtx drop_through_label = 0;
 671
 672   if (! if_false_label)
 673     drop_through_label = if_false_label = gen_label_rtx ();
 674
 675   for (i = 0; i < nwords; i++)
 676     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 677                              operand_subword_force (op1, i, mode),
 678                              EQ, TYPE_UNSIGNED (TREE_TYPE (exp)),
 679                              word_mode, NULL_RTX, if_false_label, NULL_RTX);
 680
 681   if (if_true_label)
 682     emit_jump (if_true_label);
 683   if (drop_through_label)
 684     emit_label (drop_through_label);
 685 }
 686 \f
 687 /* Jump according to whether OP0 is 0.
 688    We assume that OP0 has an integer mode that is too wide
 689    for the available compare insns.  */
 690
 691 void
 692 do_jump_by_parts_equality_rtx (rtx op0, rtx if_false_label, rtx if_true_label)
 693 {
 694   int nwords = GET_MODE_SIZE (GET_MODE (op0)) / UNITS_PER_WORD;
 695   rtx part;
 696   int i;
 697   rtx drop_through_label = 0;
 698
 699   /* The fastest way of doing this comparison on almost any machine is to
 700      "or" all the words and compare the result.  If all have to be loaded
 701      from memory and this is a very wide item, it's possible this may
 702      be slower, but that's highly unlikely.  */
 703
 704   part = gen_reg_rtx (word_mode);
 705   emit_move_insn (part, operand_subword_force (op0, 0, GET_MODE (op0)));
 706   for (i = 1; i < nwords && part != 0; i++)
 707     part = expand_binop (word_mode, ior_optab, part,
 708                          operand_subword_force (op0, i, GET_MODE (op0)),
 709                          part, 1, OPTAB_WIDEN);
 710
 711   if (part != 0)
 712     {
 713       do_compare_rtx_and_jump (part, const0_rtx, EQ, 1, word_mode,
 714                                NULL_RTX, if_false_label, if_true_label);
 715
 716       return;
 717     }
 718
 719   /* If we couldn't do the "or" simply, do this with a series of compares.  */
 720   if (! if_false_label)
 721     drop_through_label = if_false_label = gen_label_rtx ();
 722
 723   for (i = 0; i < nwords; i++)
 724     do_compare_rtx_and_jump (operand_subword_force (op0, i, GET_MODE (op0)),
 725                              const0_rtx, EQ, 1, word_mode, NULL_RTX,
 726                              if_false_label, NULL_RTX);
 727
 728   if (if_true_label)
 729     emit_jump (if_true_label);
 730
 731   if (drop_through_label)
 732     emit_label (drop_through_label);
 733 }
 734 \f
 735 /* Generate code for a comparison of OP0 and OP1 with rtx code CODE.
 736    MODE is the machine mode of the comparison, not of the result.
 737    (including code to compute the values to be compared) and set CC0
 738    according to the result.  The decision as to signed or unsigned
 739    comparison must be made by the caller.
 740
 741    We force a stack adjustment unless there are currently
 742    things pushed on the stack that aren't yet used.
 743
 744    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 745    compared.  */
 746
 747 rtx
 748 compare_from_rtx (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 749                   enum machine_mode mode, rtx size)
 750 {
 751   rtx tem;
 752
 753   /* If one operand is constant, make it the second one.  Only do this
 754      if the other operand is not constant as well.  */
 755
 756   if (swap_commutative_operands_p (op0, op1))
 757     {
 758       tem = op0;
 759       op0 = op1;
 760       op1 = tem;
 761       code = swap_condition (code);
 762     }
 763
 764   if (flag_force_mem)
 765     {
 766       op0 = force_not_mem (op0);
 767       op1 = force_not_mem (op1);
 768     }
 769
 770   do_pending_stack_adjust ();
 771
 772   code = unsignedp ? unsigned_condition (code) : code;
 773   tem = simplify_relational_operation (code, VOIDmode, mode, op0, op1);
 774   if (tem)
 775     {
 776       if (CONSTANT_P (tem))
 777         return tem;
 778
 779       if (COMPARISON_P (tem))
 780         {
 781           code = GET_CODE (tem);
 782           op0 = XEXP (tem, 0);
 783           op1 = XEXP (tem, 1);
 784           mode = GET_MODE (op0);
 785           unsignedp = (code == GTU || code == LTU
 786                        || code == GEU || code == LEU);
 787         }
 788     }
 789
 790   emit_cmp_insn (op0, op1, code, size, mode, unsignedp);
 791
 792 #if HAVE_cc0
 793   return gen_rtx_fmt_ee (code, VOIDmode, cc0_rtx, const0_rtx);
 794 #else
 795   return gen_rtx_fmt_ee (code, VOIDmode, op0, op1);
 796 #endif
 797 }
 798
 799 /* Like do_compare_and_jump but expects the values to compare as two rtx's.
 800    The decision as to signed or unsigned comparison must be made by the caller.
 801
 802    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 803    compared.  */
 804
 805 void
 806 do_compare_rtx_and_jump (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 807                          enum machine_mode mode, rtx size, rtx if_false_label,
 808                          rtx if_true_label)
 809 {
 810   rtx tem;
 811   int dummy_true_label = 0;
 812
 813   /* Reverse the comparison if that is safe and we want to jump if it is
 814      false.  */
 815   if (! if_true_label && ! FLOAT_MODE_P (mode))
 816     {
 817       if_true_label = if_false_label;
 818       if_false_label = 0;
 819       code = reverse_condition (code);
 820     }
 821
 822   /* If one operand is constant, make it the second one.  Only do this
 823      if the other operand is not constant as well.  */
 824
 825   if (swap_commutative_operands_p (op0, op1))
 826     {
 827       tem = op0;
 828       op0 = op1;
 829       op1 = tem;
 830       code = swap_condition (code);
 831     }
 832
 833   if (flag_force_mem)
 834     {
 835       op0 = force_not_mem (op0);
 836       op1 = force_not_mem (op1);
 837     }
 838
 839   do_pending_stack_adjust ();
 840
 841   code = unsignedp ? unsigned_condition (code) : code;
 842   if (0 != (tem = simplify_relational_operation (code, mode, VOIDmode,
 843                                                  op0, op1)))
 844     {
 845       if (CONSTANT_P (tem))
 846         {
 847           rtx label = (tem == const0_rtx || tem == CONST0_RTX (mode))
 848                       ? if_false_label : if_true_label;
 849           if (label)
 850             emit_jump (label);
 851           return;
 852         }
 853
 854       code = GET_CODE (tem);
 855       mode = GET_MODE (tem);
 856       op0 = XEXP (tem, 0);
 857       op1 = XEXP (tem, 1);
 858       unsignedp = (code == GTU || code == LTU || code == GEU || code == LEU);
 859     }
 860
 861   if (! if_true_label)
 862     {
 863       dummy_true_label = 1;
 864       if_true_label = gen_label_rtx ();
 865     }
 866
 867   emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp,
 868                            if_true_label);
 869
 870   if (if_false_label)
 871     emit_jump (if_false_label);
 872   if (dummy_true_label)
 873     emit_label (if_true_label);
 874 }
 875
 876 /* Generate code for a comparison expression EXP (including code to compute
 877    the values to be compared) and a conditional jump to IF_FALSE_LABEL and/or
 878    IF_TRUE_LABEL.  One of the labels can be NULL_RTX, in which case the
 879    generated code will drop through.
 880    SIGNED_CODE should be the rtx operation for this comparison for
 881    signed data; UNSIGNED_CODE, likewise for use if data is unsigned.
 882
 883    We force a stack adjustment unless there are currently
 884    things pushed on the stack that aren't yet used.  */
 885
 886 static void
 887 do_compare_and_jump (tree exp, enum rtx_code signed_code,
 888                      enum rtx_code unsigned_code, rtx if_false_label,
 889                      rtx if_true_label)
 890 {
 891   rtx op0, op1;
 892   tree type;
 893   enum machine_mode mode;
 894   int unsignedp;
 895   enum rtx_code code;
 896
 897   /* Don't crash if the comparison was erroneous.  */
 898   op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
 899   if (TREE_CODE (TREE_OPERAND (exp, 0)) == ERROR_MARK)
 900     return;
 901
 902   op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 903   if (TREE_CODE (TREE_OPERAND (exp, 1)) == ERROR_MARK)
 904     return;
 905
 906   type = TREE_TYPE (TREE_OPERAND (exp, 0));
 907   mode = TYPE_MODE (type);
 908   if (TREE_CODE (TREE_OPERAND (exp, 0)) == INTEGER_CST
 909       && (TREE_CODE (TREE_OPERAND (exp, 1)) != INTEGER_CST
 910           || (GET_MODE_BITSIZE (mode)
 911               > GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp,
 912                                                                       1)))))))
 913     {
 914       /* op0 might have been replaced by promoted constant, in which
 915          case the type of second argument should be used.  */
 916       type = TREE_TYPE (TREE_OPERAND (exp, 1));
 917       mode = TYPE_MODE (type);
 918     }
 919   unsignedp = TYPE_UNSIGNED (type);
 920   code = unsignedp ? unsigned_code : signed_code;
 921
 922 #ifdef HAVE_canonicalize_funcptr_for_compare
 923   /* If function pointers need to be "canonicalized" before they can
 924      be reliably compared, then canonicalize them.
 925      Only do this if *both* sides of the comparison are function pointers.
 926      If one side isn't, we want a noncanonicalized comparison.  See PR
 927      middle-end/17564.  */
 928   if (HAVE_canonicalize_funcptr_for_compare
 929       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == POINTER_TYPE
 930       && TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 0))))
 931           == FUNCTION_TYPE
 932       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 1))) == POINTER_TYPE
 933       && TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 1))))
 934           == FUNCTION_TYPE)
 935     {
 936       rtx new_op0 = gen_reg_rtx (mode);
 937       rtx new_op1 = gen_reg_rtx (mode);
 938
 939       emit_insn (gen_canonicalize_funcptr_for_compare (new_op0, op0));
 940       op0 = new_op0;
 941
 942       emit_insn (gen_canonicalize_funcptr_for_compare (new_op1, op1));
 943       op1 = new_op1;
 944     }
 945 #endif
 946
 947   do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode,
 948                            ((mode == BLKmode)
 949                             ? expr_size (TREE_OPERAND (exp, 0)) : NULL_RTX),
 950                            if_false_label, if_true_label);
 951 }
 952
 953 #include "gt-dojump.h"