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 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 /* When exiting from function, if safe, clear out any pending stack adjust
  54    so the adjustment won't get done.
  55
  56    Note, if the current function calls alloca, then it must have a
  57    frame pointer regardless of the value of flag_omit_frame_pointer.  */
  58
  59 void
  60 clear_pending_stack_adjust (void)
  61 {
  62   if (optimize > 0
  63       && (! flag_omit_frame_pointer || current_function_calls_alloca)
  64       && EXIT_IGNORE_STACK
  65       && ! (DECL_INLINE (current_function_decl) && ! flag_no_inline)
  66       && ! flag_inline_functions)
  67     {
  68       stack_pointer_delta -= pending_stack_adjust,
  69       pending_stack_adjust = 0;
  70     }
  71 }
  72
  73 /* Pop any previously-pushed arguments that have not been popped yet.  */
  74
  75 void
  76 do_pending_stack_adjust (void)
  77 {
  78   if (inhibit_defer_pop == 0)
  79     {
  80       if (pending_stack_adjust != 0)
  81         adjust_stack (GEN_INT (pending_stack_adjust));
  82       pending_stack_adjust = 0;
  83     }
  84 }
  85 \f
  86 /* Expand conditional expressions.  */
  87
  88 /* Generate code to evaluate EXP and jump to LABEL if the value is zero.
  89    LABEL is an rtx of code CODE_LABEL, in this function and all the
  90    functions here.  */
  91
  92 void
  93 jumpifnot (tree exp, rtx label)
  94 {
  95   do_jump (exp, label, NULL_RTX);
  96 }
  97
  98 /* Generate code to evaluate EXP and jump to LABEL if the value is nonzero.  */
  99
 100 void
 101 jumpif (tree exp, rtx label)
 102 {
 103   do_jump (exp, NULL_RTX, label);
 104 }
 105
 106 /* Used internally by prefer_and_bit_test.  */
 107
 108 static GTY(()) rtx and_reg;
 109 static GTY(()) rtx and_test;
 110 static GTY(()) rtx shift_test;
 111
 112 /* Compare the relative costs of "(X & (1 << BITNUM))" and "(X >> BITNUM) & 1",
 113    where X is an arbitrary register of mode MODE.  Return true if the former
 114    is preferred.  */
 115
 116 static bool
 117 prefer_and_bit_test (enum machine_mode mode, int bitnum)
 118 {
 119   if (and_test == 0)
 120     {
 121       /* Set up rtxes for the two variations.  Use NULL as a placeholder
 122          for the BITNUM-based constants.  */
 123       and_reg = gen_rtx_REG (mode, FIRST_PSEUDO_REGISTER);
 124       and_test = gen_rtx_AND (mode, and_reg, NULL);
 125       shift_test = gen_rtx_AND (mode, gen_rtx_ASHIFTRT (mode, and_reg, NULL),
 126                                 const1_rtx);
 127     }
 128   else
 129     {
 130       /* Change the mode of the previously-created rtxes.  */
 131       PUT_MODE (and_reg, mode);
 132       PUT_MODE (and_test, mode);
 133       PUT_MODE (shift_test, mode);
 134       PUT_MODE (XEXP (shift_test, 0), mode);
 135     }
 136
 137   /* Fill in the integers.  */
 138   XEXP (and_test, 1) = GEN_INT ((unsigned HOST_WIDE_INT) 1 << bitnum);
 139   XEXP (XEXP (shift_test, 0), 1) = GEN_INT (bitnum);
 140
 141   return (rtx_cost (and_test, IF_THEN_ELSE)
 142           <= rtx_cost (shift_test, IF_THEN_ELSE));
 143 }
 144
 145 /* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if
 146    the result is zero, or IF_TRUE_LABEL if the result is one.
 147    Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero,
 148    meaning fall through in that case.
 149
 150    do_jump always does any pending stack adjust except when it does not
 151    actually perform a jump.  An example where there is no jump
 152    is when EXP is `(foo (), 0)' and IF_FALSE_LABEL is null.
 153
 154    This function is responsible for optimizing cases such as
 155    &&, || and comparison operators in EXP.  */
 156
 157 void
 158 do_jump (tree exp, rtx if_false_label, rtx if_true_label)
 159 {
 160   enum tree_code code = TREE_CODE (exp);
 161   /* Some cases need to create a label to jump to
 162      in order to properly fall through.
 163      These cases set DROP_THROUGH_LABEL nonzero.  */
 164   rtx drop_through_label = 0;
 165   rtx temp;
 166   int i;
 167   tree type;
 168   enum machine_mode mode;
 169
 170   emit_queue ();
 171
 172   switch (code)
 173     {
 174     case ERROR_MARK:
 175       break;
 176
 177     case INTEGER_CST:
 178       temp = integer_zerop (exp) ? if_false_label : if_true_label;
 179       if (temp)
 180         emit_jump (temp);
 181       break;
 182
 183 #if 0
 184       /* This is not true with #pragma weak  */
 185     case ADDR_EXPR:
 186       /* The address of something can never be zero.  */
 187       if (if_true_label)
 188         emit_jump (if_true_label);
 189       break;
 190 #endif
 191
 192     case UNSAVE_EXPR:
 193       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 194       TREE_OPERAND (exp, 0)
 195         = lang_hooks.unsave_expr_now (TREE_OPERAND (exp, 0));
 196       break;
 197
 198     case NOP_EXPR:
 199       if (TREE_CODE (TREE_OPERAND (exp, 0)) == COMPONENT_REF
 200           || TREE_CODE (TREE_OPERAND (exp, 0)) == BIT_FIELD_REF
 201           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF
 202           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_RANGE_REF)
 203         goto normal;
 204     case CONVERT_EXPR:
 205       /* If we are narrowing the operand, we have to do the compare in the
 206          narrower mode.  */
 207       if ((TYPE_PRECISION (TREE_TYPE (exp))
 208            < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
 209         goto normal;
 210     case NON_LVALUE_EXPR:
 211     case REFERENCE_EXPR:
 212     case ABS_EXPR:
 213     case NEGATE_EXPR:
 214     case LROTATE_EXPR:
 215     case RROTATE_EXPR:
 216       /* These cannot change zero->nonzero or vice versa.  */
 217       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 218       break;
 219
 220 #if 0
 221       /* This is never less insns than evaluating the PLUS_EXPR followed by
 222          a test and can be longer if the test is eliminated.  */
 223     case PLUS_EXPR:
 224       /* Reduce to minus.  */
 225       exp = build (MINUS_EXPR, TREE_TYPE (exp),
 226                    TREE_OPERAND (exp, 0),
 227                    fold (build1 (NEGATE_EXPR, TREE_TYPE (TREE_OPERAND (exp, 1)),
 228                                  TREE_OPERAND (exp, 1))));
 229       /* Process as MINUS.  */
 230 #endif
 231
 232     case MINUS_EXPR:
 233       /* Nonzero iff operands of minus differ.  */
 234       do_compare_and_jump (build (NE_EXPR, TREE_TYPE (exp),
 235                                   TREE_OPERAND (exp, 0),
 236                                   TREE_OPERAND (exp, 1)),
 237                            NE, NE, if_false_label, if_true_label);
 238       break;
 239
 240     case BIT_AND_EXPR:
 241       /* fold_single_bit_test() converts (X & (1 << C)) into (X >> C) & 1.
 242          See if the former is preferred for jump tests and restore it
 243          if so.  */
 244       if (TREE_CODE (TREE_OPERAND (exp, 0)) == RSHIFT_EXPR
 245           && integer_onep (TREE_OPERAND (exp, 1)))
 246         {
 247           tree arg = TREE_OPERAND (TREE_OPERAND (exp, 0), 0);
 248           tree shift = TREE_OPERAND (TREE_OPERAND (exp, 0), 1);
 249           tree one = TREE_OPERAND (exp, 1);
 250           tree argtype = TREE_TYPE (arg);
 251           if (TREE_CODE (shift) == INTEGER_CST
 252               && compare_tree_int (shift, 0) > 0
 253               && compare_tree_int (shift, HOST_BITS_PER_WIDE_INT) < 0
 254               && prefer_and_bit_test (TYPE_MODE (argtype),
 255                                       TREE_INT_CST_LOW (shift)))
 256             {
 257               do_jump (build (BIT_AND_EXPR, argtype, arg,
 258                               fold (build (LSHIFT_EXPR, argtype, one, shift))),
 259                        if_false_label, if_true_label);
 260               break;
 261             }
 262         }
 263
 264       /* If we are AND'ing with a small constant, do this comparison in the
 265          smallest type that fits.  If the machine doesn't have comparisons
 266          that small, it will be converted back to the wider comparison.
 267          This helps if we are testing the sign bit of a narrower object.
 268          combine can't do this for us because it can't know whether a
 269          ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */
 270
 271       if (! SLOW_BYTE_ACCESS
 272           && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
 273           && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT
 274           && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0
 275           && (mode = mode_for_size (i + 1, MODE_INT, 0)) != BLKmode
 276           && (type = lang_hooks.types.type_for_mode (mode, 1)) != 0
 277           && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 278           && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 279               != CODE_FOR_nothing))
 280         {
 281           do_jump (convert (type, exp), if_false_label, if_true_label);
 282           break;
 283         }
 284       goto normal;
 285
 286     case TRUTH_NOT_EXPR:
 287       do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 288       break;
 289
 290     case TRUTH_ANDIF_EXPR:
 291       if (if_false_label == 0)
 292         if_false_label = drop_through_label = gen_label_rtx ();
 293       do_jump (TREE_OPERAND (exp, 0), if_false_label, NULL_RTX);
 294       start_cleanup_deferral ();
 295       do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 296       end_cleanup_deferral ();
 297       break;
 298
 299     case TRUTH_ORIF_EXPR:
 300       if (if_true_label == 0)
 301         if_true_label = drop_through_label = gen_label_rtx ();
 302       do_jump (TREE_OPERAND (exp, 0), NULL_RTX, if_true_label);
 303       start_cleanup_deferral ();
 304       do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 305       end_cleanup_deferral ();
 306       break;
 307
 308     case COMPOUND_EXPR:
 309       push_temp_slots ();
 310       expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, 0);
 311       preserve_temp_slots (NULL_RTX);
 312       free_temp_slots ();
 313       pop_temp_slots ();
 314       emit_queue ();
 315       do_pending_stack_adjust ();
 316       do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 317       break;
 318
 319     case COMPONENT_REF:
 320     case BIT_FIELD_REF:
 321     case ARRAY_REF:
 322     case ARRAY_RANGE_REF:
 323       {
 324         HOST_WIDE_INT bitsize, bitpos;
 325         int unsignedp;
 326         enum machine_mode mode;
 327         tree type;
 328         tree offset;
 329         int volatilep = 0;
 330
 331         /* Get description of this reference.  We don't actually care
 332            about the underlying object here.  */
 333         get_inner_reference (exp, &bitsize, &bitpos, &offset, &mode,
 334                              &unsignedp, &volatilep);
 335
 336         type = lang_hooks.types.type_for_size (bitsize, unsignedp);
 337         if (! SLOW_BYTE_ACCESS
 338             && type != 0 && bitsize >= 0
 339             && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 340             && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 341                 != CODE_FOR_nothing))
 342           {
 343             do_jump (convert (type, exp), if_false_label, if_true_label);
 344             break;
 345           }
 346         goto normal;
 347       }
 348
 349     case COND_EXPR:
 350       /* Do (a ? 1 : 0) and (a ? 0 : 1) as special cases.  */
 351       if (integer_onep (TREE_OPERAND (exp, 1))
 352           && integer_zerop (TREE_OPERAND (exp, 2)))
 353         do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 354
 355       else if (integer_zerop (TREE_OPERAND (exp, 1))
 356                && integer_onep (TREE_OPERAND (exp, 2)))
 357         do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 358
 359       else
 360       {
 361         rtx label1 = gen_label_rtx ();
 362         drop_through_label = gen_label_rtx ();
 363
 364         do_jump (TREE_OPERAND (exp, 0), label1, NULL_RTX);
 365
 366         start_cleanup_deferral ();
 367         /* Now the THEN-expression.  */
 368         do_jump (TREE_OPERAND (exp, 1),
 369                  if_false_label ? if_false_label : drop_through_label,
 370                  if_true_label ? if_true_label : drop_through_label);
 371         /* In case the do_jump just above never jumps.  */
 372         do_pending_stack_adjust ();
 373         emit_label (label1);
 374
 375         /* Now the ELSE-expression.  */
 376         do_jump (TREE_OPERAND (exp, 2),
 377            if_false_label ? if_false_label : drop_through_label,
 378            if_true_label ? if_true_label : drop_through_label);
 379         end_cleanup_deferral ();
 380       }
 381       break;
 382
 383     case EQ_EXPR:
 384       {
 385         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 386
 387         if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_FLOAT
 388             || GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_INT)
 389           {
 390             tree exp0 = save_expr (TREE_OPERAND (exp, 0));
 391             tree exp1 = save_expr (TREE_OPERAND (exp, 1));
 392             do_jump
 393               (fold
 394                (build (TRUTH_ANDIF_EXPR, TREE_TYPE (exp),
 395                  fold (build (EQ_EXPR, TREE_TYPE (exp),
 396                   fold (build1 (REALPART_EXPR,
 397                     TREE_TYPE (inner_type),
 398                     exp0)),
 399                   fold (build1 (REALPART_EXPR,
 400                     TREE_TYPE (inner_type),
 401                     exp1)))),
 402                  fold (build (EQ_EXPR, TREE_TYPE (exp),
 403                   fold (build1 (IMAGPART_EXPR,
 404                     TREE_TYPE (inner_type),
 405                     exp0)),
 406                   fold (build1 (IMAGPART_EXPR,
 407                     TREE_TYPE (inner_type),
 408                     exp1)))))),
 409                if_false_label, if_true_label);
 410           }
 411
 412         else if (integer_zerop (TREE_OPERAND (exp, 1)))
 413           do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 414
 415         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 416                  && !can_compare_p (EQ, TYPE_MODE (inner_type), ccp_jump))
 417           do_jump_by_parts_equality (exp, if_false_label, if_true_label);
 418         else
 419           do_compare_and_jump (exp, EQ, EQ, if_false_label, if_true_label);
 420         break;
 421       }
 422
 423     case NE_EXPR:
 424       {
 425         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 426
 427         if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_FLOAT
 428             || GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_INT)
 429           {
 430             tree exp0 = save_expr (TREE_OPERAND (exp, 0));
 431             tree exp1 = save_expr (TREE_OPERAND (exp, 1));
 432             do_jump
 433               (fold
 434                (build (TRUTH_ORIF_EXPR, TREE_TYPE (exp),
 435                  fold (build (NE_EXPR, TREE_TYPE (exp),
 436                   fold (build1 (REALPART_EXPR,
 437                     TREE_TYPE (inner_type),
 438                     exp0)),
 439                   fold (build1 (REALPART_EXPR,
 440                     TREE_TYPE (inner_type),
 441                     exp1)))),
 442                  fold (build (NE_EXPR, TREE_TYPE (exp),
 443                     fold (build1 (IMAGPART_EXPR,
 444                       TREE_TYPE (inner_type),
 445                       exp0)),
 446                     fold (build1 (IMAGPART_EXPR,
 447                       TREE_TYPE (inner_type),
 448                       exp1)))))),
 449                if_false_label, if_true_label);
 450           }
 451
 452         else if (integer_zerop (TREE_OPERAND (exp, 1)))
 453           do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 454
 455         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 456            && !can_compare_p (NE, TYPE_MODE (inner_type), ccp_jump))
 457           do_jump_by_parts_equality (exp, if_true_label, if_false_label);
 458         else
 459           do_compare_and_jump (exp, NE, NE, if_false_label, if_true_label);
 460         break;
 461       }
 462
 463     case LT_EXPR:
 464       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 465       if (GET_MODE_CLASS (mode) == MODE_INT
 466           && ! can_compare_p (LT, mode, ccp_jump))
 467         do_jump_by_parts_greater (exp, 1, if_false_label, if_true_label);
 468       else
 469         do_compare_and_jump (exp, LT, LTU, if_false_label, if_true_label);
 470       break;
 471
 472     case LE_EXPR:
 473       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 474       if (GET_MODE_CLASS (mode) == MODE_INT
 475           && ! can_compare_p (LE, mode, ccp_jump))
 476         do_jump_by_parts_greater (exp, 0, if_true_label, if_false_label);
 477       else
 478         do_compare_and_jump (exp, LE, LEU, if_false_label, if_true_label);
 479       break;
 480
 481     case GT_EXPR:
 482       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 483       if (GET_MODE_CLASS (mode) == MODE_INT
 484           && ! can_compare_p (GT, mode, ccp_jump))
 485         do_jump_by_parts_greater (exp, 0, if_false_label, if_true_label);
 486       else
 487         do_compare_and_jump (exp, GT, GTU, if_false_label, if_true_label);
 488       break;
 489
 490     case GE_EXPR:
 491       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 492       if (GET_MODE_CLASS (mode) == MODE_INT
 493           && ! can_compare_p (GE, mode, ccp_jump))
 494         do_jump_by_parts_greater (exp, 1, if_true_label, if_false_label);
 495       else
 496         do_compare_and_jump (exp, GE, GEU, if_false_label, if_true_label);
 497       break;
 498
 499     case UNORDERED_EXPR:
 500     case ORDERED_EXPR:
 501       {
 502         enum rtx_code cmp, rcmp;
 503         int do_rev;
 504
 505         if (code == UNORDERED_EXPR)
 506           cmp = UNORDERED, rcmp = ORDERED;
 507         else
 508           cmp = ORDERED, rcmp = UNORDERED;
 509         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 510
 511         do_rev = 0;
 512         if (! can_compare_p (cmp, mode, ccp_jump)
 513             && (can_compare_p (rcmp, mode, ccp_jump)
 514           /* If the target doesn't provide either UNORDERED or ORDERED
 515              comparisons, canonicalize on UNORDERED for the library.  */
 516           || rcmp == UNORDERED))
 517           do_rev = 1;
 518
 519         if (! do_rev)
 520           do_compare_and_jump (exp, cmp, cmp, if_false_label, if_true_label);
 521         else
 522           do_compare_and_jump (exp, rcmp, rcmp, if_true_label, if_false_label);
 523       }
 524       break;
 525
 526     {
 527       enum rtx_code rcode1;
 528       enum tree_code tcode1, tcode2;
 529
 530       case UNLT_EXPR:
 531         rcode1 = UNLT;
 532         tcode1 = UNORDERED_EXPR;
 533         tcode2 = LT_EXPR;
 534         goto unordered_bcc;
 535       case UNLE_EXPR:
 536         rcode1 = UNLE;
 537         tcode1 = UNORDERED_EXPR;
 538         tcode2 = LE_EXPR;
 539         goto unordered_bcc;
 540       case UNGT_EXPR:
 541         rcode1 = UNGT;
 542         tcode1 = UNORDERED_EXPR;
 543         tcode2 = GT_EXPR;
 544         goto unordered_bcc;
 545       case UNGE_EXPR:
 546         rcode1 = UNGE;
 547         tcode1 = UNORDERED_EXPR;
 548         tcode2 = GE_EXPR;
 549         goto unordered_bcc;
 550       case UNEQ_EXPR:
 551         rcode1 = UNEQ;
 552         tcode1 = UNORDERED_EXPR;
 553         tcode2 = EQ_EXPR;
 554         goto unordered_bcc;
 555       case LTGT_EXPR:
 556         /* It is ok for LTGT_EXPR to trap when the result is unordered,
 557            so expand to (a < b) || (a > b).  */
 558         rcode1 = LTGT;
 559         tcode1 = LT_EXPR;
 560         tcode2 = GT_EXPR;
 561         goto unordered_bcc;
 562
 563       unordered_bcc:
 564         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 565         if (can_compare_p (rcode1, mode, ccp_jump))
 566           do_compare_and_jump (exp, rcode1, rcode1, if_false_label,
 567                                if_true_label);
 568         else
 569           {
 570             tree op0 = save_expr (TREE_OPERAND (exp, 0));
 571             tree op1 = save_expr (TREE_OPERAND (exp, 1));
 572             tree cmp0, cmp1;
 573
 574             /* If the target doesn't support combined unordered
 575                compares, decompose into two comparisons.  */
 576             cmp0 = fold (build (tcode1, TREE_TYPE (exp), op0, op1));
 577             cmp1 = fold (build (tcode2, TREE_TYPE (exp), op0, op1));
 578             exp = build (TRUTH_ORIF_EXPR, TREE_TYPE (exp), cmp0, cmp1);
 579             do_jump (exp, if_false_label, if_true_label);
 580           }
 581       }
 582       break;
 583
 584       /* Special case:
 585           __builtin_expect (<test>, 0)  and
 586           __builtin_expect (<test>, 1)
 587
 588          We need to do this here, so that <test> is not converted to a SCC
 589          operation on machines that use condition code registers and COMPARE
 590          like the PowerPC, and then the jump is done based on whether the SCC
 591          operation produced a 1 or 0.  */
 592     case CALL_EXPR:
 593       /* Check for a built-in function.  */
 594       {
 595         tree fndecl = get_callee_fndecl (exp);
 596         tree arglist = TREE_OPERAND (exp, 1);
 597
 598         if (fndecl
 599             && DECL_BUILT_IN (fndecl)
 600             && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT
 601             && arglist != NULL_TREE
 602             && TREE_CHAIN (arglist) != NULL_TREE)
 603           {
 604             rtx seq = expand_builtin_expect_jump (exp, if_false_label,
 605                                                   if_true_label);
 606
 607             if (seq != NULL_RTX)
 608               {
 609                 emit_insn (seq);
 610                 return;
 611               }
 612           }
 613       }
 614       /* Fall through and generate the normal code.  */
 615
 616     default:
 617     normal:
 618       temp = expand_expr (exp, NULL_RTX, VOIDmode, 0);
 619 #if 0
 620       /* This is not needed any more and causes poor code since it causes
 621          comparisons and tests from non-SI objects to have different code
 622          sequences.  */
 623       /* Copy to register to avoid generating bad insns by cse
 624          from (set (mem ...) (arithop))  (set (cc0) (mem ...)).  */
 625       if (!cse_not_expected && MEM_P (temp))
 626         temp = copy_to_reg (temp);
 627 #endif
 628       do_pending_stack_adjust ();
 629       /* Do any postincrements in the expression that was tested.  */
 630       emit_queue ();
 631
 632       if (GET_CODE (temp) == CONST_INT
 633           || (GET_CODE (temp) == CONST_DOUBLE && GET_MODE (temp) == VOIDmode)
 634           || GET_CODE (temp) == LABEL_REF)
 635         {
 636           rtx target = temp == const0_rtx ? if_false_label : if_true_label;
 637           if (target)
 638             emit_jump (target);
 639         }
 640       else if (GET_MODE_CLASS (GET_MODE (temp)) == MODE_INT
 641                && ! can_compare_p (NE, GET_MODE (temp), ccp_jump))
 642         /* Note swapping the labels gives us not-equal.  */
 643         do_jump_by_parts_equality_rtx (temp, if_true_label, if_false_label);
 644       else if (GET_MODE (temp) != VOIDmode)
 645         {
 646           /* The RTL optimizers prefer comparisons against pseudos.  */
 647           if (GET_CODE (temp) == SUBREG)
 648             {
 649               /* Compare promoted variables in their promoted mode.  */
 650               if (SUBREG_PROMOTED_VAR_P (temp)
 651                   && REG_P (XEXP (temp, 0)))
 652                 temp = XEXP (temp, 0);
 653               else
 654                 temp = copy_to_reg (temp);
 655             }
 656           do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),
 657                                    NE, TYPE_UNSIGNED (TREE_TYPE (exp)),
 658                                    GET_MODE (temp), NULL_RTX,
 659                                    if_false_label, if_true_label);
 660         }
 661       else
 662         abort ();
 663     }
 664
 665   if (drop_through_label)
 666     {
 667       /* If do_jump produces code that might be jumped around,
 668          do any stack adjusts from that code, before the place
 669          where control merges in.  */
 670       do_pending_stack_adjust ();
 671       emit_label (drop_through_label);
 672     }
 673 }
 674 \f
 675 /* Given a comparison expression EXP for values too wide to be compared
 676    with one insn, test the comparison and jump to the appropriate label.
 677    The code of EXP is ignored; we always test GT if SWAP is 0,
 678    and LT if SWAP is 1.  */
 679
 680 static void
 681 do_jump_by_parts_greater (tree exp, int swap, rtx if_false_label,
 682                           rtx if_true_label)
 683 {
 684   rtx op0 = expand_expr (TREE_OPERAND (exp, swap), NULL_RTX, VOIDmode, 0);
 685   rtx op1 = expand_expr (TREE_OPERAND (exp, !swap), NULL_RTX, VOIDmode, 0);
 686   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 687   int unsignedp = TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)));
 688
 689   do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label,
 690                                 if_true_label);
 691 }
 692
 693 /* Compare OP0 with OP1, word at a time, in mode MODE.
 694    UNSIGNEDP says to do unsigned comparison.
 695    Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */
 696
 697 void
 698 do_jump_by_parts_greater_rtx (enum machine_mode mode, int unsignedp, rtx op0,
 699                               rtx op1, rtx if_false_label, rtx if_true_label)
 700 {
 701   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 702   rtx drop_through_label = 0;
 703   int i;
 704
 705   if (! if_true_label || ! if_false_label)
 706     drop_through_label = gen_label_rtx ();
 707   if (! if_true_label)
 708     if_true_label = drop_through_label;
 709   if (! if_false_label)
 710     if_false_label = drop_through_label;
 711
 712   /* Compare a word at a time, high order first.  */
 713   for (i = 0; i < nwords; i++)
 714     {
 715       rtx op0_word, op1_word;
 716
 717       if (WORDS_BIG_ENDIAN)
 718         {
 719           op0_word = operand_subword_force (op0, i, mode);
 720           op1_word = operand_subword_force (op1, i, mode);
 721         }
 722       else
 723         {
 724           op0_word = operand_subword_force (op0, nwords - 1 - i, mode);
 725           op1_word = operand_subword_force (op1, nwords - 1 - i, mode);
 726         }
 727
 728       /* All but high-order word must be compared as unsigned.  */
 729       do_compare_rtx_and_jump (op0_word, op1_word, GT,
 730                                (unsignedp || i > 0), word_mode, NULL_RTX,
 731                                NULL_RTX, if_true_label);
 732
 733       /* Consider lower words only if these are equal.  */
 734       do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,
 735                                NULL_RTX, NULL_RTX, if_false_label);
 736     }
 737
 738   if (if_false_label)
 739     emit_jump (if_false_label);
 740   if (drop_through_label)
 741     emit_label (drop_through_label);
 742 }
 743
 744 /* Given an EQ_EXPR expression EXP for values too wide to be compared
 745    with one insn, test the comparison and jump to the appropriate label.  */
 746
 747 static void
 748 do_jump_by_parts_equality (tree exp, rtx if_false_label, rtx if_true_label)
 749 {
 750   rtx op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
 751   rtx op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 752   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 753   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 754   int i;
 755   rtx drop_through_label = 0;
 756
 757   if (! if_false_label)
 758     drop_through_label = if_false_label = gen_label_rtx ();
 759
 760   for (i = 0; i < nwords; i++)
 761     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 762                              operand_subword_force (op1, i, mode),
 763                              EQ, TYPE_UNSIGNED (TREE_TYPE (exp)),
 764                              word_mode, NULL_RTX, if_false_label, NULL_RTX);
 765
 766   if (if_true_label)
 767     emit_jump (if_true_label);
 768   if (drop_through_label)
 769     emit_label (drop_through_label);
 770 }
 771 \f
 772 /* Jump according to whether OP0 is 0.
 773    We assume that OP0 has an integer mode that is too wide
 774    for the available compare insns.  */
 775
 776 void
 777 do_jump_by_parts_equality_rtx (rtx op0, rtx if_false_label, rtx if_true_label)
 778 {
 779   int nwords = GET_MODE_SIZE (GET_MODE (op0)) / UNITS_PER_WORD;
 780   rtx part;
 781   int i;
 782   rtx drop_through_label = 0;
 783
 784   /* The fastest way of doing this comparison on almost any machine is to
 785      "or" all the words and compare the result.  If all have to be loaded
 786      from memory and this is a very wide item, it's possible this may
 787      be slower, but that's highly unlikely.  */
 788
 789   part = gen_reg_rtx (word_mode);
 790   emit_move_insn (part, operand_subword_force (op0, 0, GET_MODE (op0)));
 791   for (i = 1; i < nwords && part != 0; i++)
 792     part = expand_binop (word_mode, ior_optab, part,
 793                          operand_subword_force (op0, i, GET_MODE (op0)),
 794                          part, 1, OPTAB_WIDEN);
 795
 796   if (part != 0)
 797     {
 798       do_compare_rtx_and_jump (part, const0_rtx, EQ, 1, word_mode,
 799                                NULL_RTX, if_false_label, if_true_label);
 800
 801       return;
 802     }
 803
 804   /* If we couldn't do the "or" simply, do this with a series of compares.  */
 805   if (! if_false_label)
 806     drop_through_label = if_false_label = gen_label_rtx ();
 807
 808   for (i = 0; i < nwords; i++)
 809     do_compare_rtx_and_jump (operand_subword_force (op0, i, GET_MODE (op0)),
 810                              const0_rtx, EQ, 1, word_mode, NULL_RTX,
 811                              if_false_label, NULL_RTX);
 812
 813   if (if_true_label)
 814     emit_jump (if_true_label);
 815
 816   if (drop_through_label)
 817     emit_label (drop_through_label);
 818 }
 819 \f
 820 /* Generate code for a comparison of OP0 and OP1 with rtx code CODE.
 821    (including code to compute the values to be compared)
 822    and set (CC0) according to the result.
 823    The decision as to signed or unsigned comparison must be made by the caller.
 824
 825    We force a stack adjustment unless there are currently
 826    things pushed on the stack that aren't yet used.
 827
 828    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 829    compared.  */
 830
 831 rtx
 832 compare_from_rtx (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 833                   enum machine_mode mode, rtx size)
 834 {
 835   rtx tem;
 836
 837   /* If one operand is constant, make it the second one.  Only do this
 838      if the other operand is not constant as well.  */
 839
 840   if (swap_commutative_operands_p (op0, op1))
 841     {
 842       tem = op0;
 843       op0 = op1;
 844       op1 = tem;
 845       code = swap_condition (code);
 846     }
 847
 848   if (flag_force_mem)
 849     {
 850       op0 = force_not_mem (op0);
 851       op1 = force_not_mem (op1);
 852     }
 853
 854   do_pending_stack_adjust ();
 855
 856   code = unsignedp ? unsigned_condition (code) : code;
 857   if (0 != (tem = simplify_relational_operation (code, mode, VOIDmode,
 858                                                  op0, op1)))
 859     {
 860       if (CONSTANT_P (tem))
 861         return tem;
 862
 863       code = GET_CODE (tem);
 864       mode = GET_MODE (tem);
 865       op0 = XEXP (tem, 0);
 866       op1 = XEXP (tem, 1);
 867       unsignedp = (code == GTU || code == LTU || code == GEU || code == LEU);
 868     }
 869
 870   emit_cmp_insn (op0, op1, code, size, mode, unsignedp);
 871
 872 #if HAVE_cc0
 873   return gen_rtx_fmt_ee (code, VOIDmode, cc0_rtx, const0_rtx);
 874 #else
 875   return gen_rtx_fmt_ee (code, VOIDmode, op0, op1);
 876 #endif
 877 }
 878
 879 /* Like do_compare_and_jump but expects the values to compare as two rtx's.
 880    The decision as to signed or unsigned comparison must be made by the caller.
 881
 882    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 883    compared.  */
 884
 885 void
 886 do_compare_rtx_and_jump (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 887                          enum machine_mode mode, rtx size, rtx if_false_label,
 888                          rtx if_true_label)
 889 {
 890   rtx tem;
 891   int dummy_true_label = 0;
 892
 893   /* Reverse the comparison if that is safe and we want to jump if it is
 894      false.  */
 895   if (! if_true_label && ! FLOAT_MODE_P (mode))
 896     {
 897       if_true_label = if_false_label;
 898       if_false_label = 0;
 899       code = reverse_condition (code);
 900     }
 901
 902   /* If one operand is constant, make it the second one.  Only do this
 903      if the other operand is not constant as well.  */
 904
 905   if (swap_commutative_operands_p (op0, op1))
 906     {
 907       tem = op0;
 908       op0 = op1;
 909       op1 = tem;
 910       code = swap_condition (code);
 911     }
 912
 913   if (flag_force_mem)
 914     {
 915       op0 = force_not_mem (op0);
 916       op1 = force_not_mem (op1);
 917     }
 918
 919   do_pending_stack_adjust ();
 920
 921   code = unsignedp ? unsigned_condition (code) : code;
 922   if (0 != (tem = simplify_relational_operation (code, mode, VOIDmode,
 923                                                  op0, op1)))
 924     {
 925       if (CONSTANT_P (tem))
 926         {
 927           rtx label = (tem == const0_rtx || tem == CONST0_RTX (mode))
 928                       ? if_false_label : if_true_label;
 929           if (label)
 930             emit_jump (label);
 931           return;
 932         }
 933
 934       code = GET_CODE (tem);
 935       mode = GET_MODE (tem);
 936       op0 = XEXP (tem, 0);
 937       op1 = XEXP (tem, 1);
 938       unsignedp = (code == GTU || code == LTU || code == GEU || code == LEU);
 939     }
 940
 941   if (! if_true_label)
 942     {
 943       dummy_true_label = 1;
 944       if_true_label = gen_label_rtx ();
 945     }
 946
 947   emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp,
 948                            if_true_label);
 949
 950   if (if_false_label)
 951     emit_jump (if_false_label);
 952   if (dummy_true_label)
 953     emit_label (if_true_label);
 954 }
 955
 956 /* Generate code for a comparison expression EXP (including code to compute
 957    the values to be compared) and a conditional jump to IF_FALSE_LABEL and/or
 958    IF_TRUE_LABEL.  One of the labels can be NULL_RTX, in which case the
 959    generated code will drop through.
 960    SIGNED_CODE should be the rtx operation for this comparison for
 961    signed data; UNSIGNED_CODE, likewise for use if data is unsigned.
 962
 963    We force a stack adjustment unless there are currently
 964    things pushed on the stack that aren't yet used.  */
 965
 966 static void
 967 do_compare_and_jump (tree exp, enum rtx_code signed_code,
 968                      enum rtx_code unsigned_code, rtx if_false_label,
 969                      rtx if_true_label)
 970 {
 971   rtx op0, op1;
 972   tree type;
 973   enum machine_mode mode;
 974   int unsignedp;
 975   enum rtx_code code;
 976
 977   /* Don't crash if the comparison was erroneous.  */
 978   op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
 979   if (TREE_CODE (TREE_OPERAND (exp, 0)) == ERROR_MARK)
 980     return;
 981
 982   op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 983   if (TREE_CODE (TREE_OPERAND (exp, 1)) == ERROR_MARK)
 984     return;
 985
 986   type = TREE_TYPE (TREE_OPERAND (exp, 0));
 987   mode = TYPE_MODE (type);
 988   if (TREE_CODE (TREE_OPERAND (exp, 0)) == INTEGER_CST
 989       && (TREE_CODE (TREE_OPERAND (exp, 1)) != INTEGER_CST
 990           || (GET_MODE_BITSIZE (mode)
 991               > GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp,
 992                                                                       1)))))))
 993     {
 994       /* op0 might have been replaced by promoted constant, in which
 995          case the type of second argument should be used.  */
 996       type = TREE_TYPE (TREE_OPERAND (exp, 1));
 997       mode = TYPE_MODE (type);
 998     }
 999   unsignedp = TYPE_UNSIGNED (type);
1000   code = unsignedp ? unsigned_code : signed_code;
1001
1002 #ifdef HAVE_canonicalize_funcptr_for_compare
1003   /* If function pointers need to be "canonicalized" before they can
1004      be reliably compared, then canonicalize them.  */
1005   if (HAVE_canonicalize_funcptr_for_compare
1006       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == POINTER_TYPE
1007       && (TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 0))))
1008           == FUNCTION_TYPE))
1009     {
1010       rtx new_op0 = gen_reg_rtx (mode);
1011
1012       emit_insn (gen_canonicalize_funcptr_for_compare (new_op0, op0));
1013       op0 = new_op0;
1014     }
1015
1016   if (HAVE_canonicalize_funcptr_for_compare
1017       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 1))) == POINTER_TYPE
1018       && (TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 1))))
1019           == FUNCTION_TYPE))
1020     {
1021       rtx new_op1 = gen_reg_rtx (mode);
1022
1023       emit_insn (gen_canonicalize_funcptr_for_compare (new_op1, op1));
1024       op1 = new_op1;
1025     }
1026 #endif
1027
1028   /* Do any postincrements in the expression that was tested.  */
1029   emit_queue ();
1030
1031   do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode,
1032                            ((mode == BLKmode)
1033                             ? expr_size (TREE_OPERAND (exp, 0)) : NULL_RTX),
1034                            if_false_label, if_true_label);
1035 }
1036
1037 #include "gt-dojump.h"