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 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
  37 static void do_jump_by_parts_greater (tree, int, rtx, rtx);
  38 static void do_jump_by_parts_equality (tree, rtx, rtx);
  39 static void do_compare_and_jump (tree, enum rtx_code, enum rtx_code, rtx,
  40                                  rtx);
  41
  42 /* At the start of a function, record that we have no previously-pushed
  43    arguments waiting to be popped.  */
  44
  45 void
  46 init_pending_stack_adjust (void)
  47 {
  48   pending_stack_adjust = 0;
  49 }
  50
  51 /* When exiting from function, if safe, clear out any pending stack adjust
  52    so the adjustment won't get done.
  53
  54    Note, if the current function calls alloca, then it must have a
  55    frame pointer regardless of the value of flag_omit_frame_pointer.  */
  56
  57 void
  58 clear_pending_stack_adjust (void)
  59 {
  60   if (optimize > 0
  61       && (! flag_omit_frame_pointer || current_function_calls_alloca)
  62       && EXIT_IGNORE_STACK
  63       && ! (DECL_INLINE (current_function_decl) && ! flag_no_inline)
  64       && ! flag_inline_functions)
  65     {
  66       stack_pointer_delta -= pending_stack_adjust,
  67       pending_stack_adjust = 0;
  68     }
  69 }
  70
  71 /* Pop any previously-pushed arguments that have not been popped yet.  */
  72
  73 void
  74 do_pending_stack_adjust (void)
  75 {
  76   if (inhibit_defer_pop == 0)
  77     {
  78       if (pending_stack_adjust != 0)
  79         adjust_stack (GEN_INT (pending_stack_adjust));
  80       pending_stack_adjust = 0;
  81     }
  82 }
  83 \f
  84 /* Expand conditional expressions.  */
  85
  86 /* Generate code to evaluate EXP and jump to LABEL if the value is zero.
  87    LABEL is an rtx of code CODE_LABEL, in this function and all the
  88    functions here.  */
  89
  90 void
  91 jumpifnot (tree exp, rtx label)
  92 {
  93   do_jump (exp, label, NULL_RTX);
  94 }
  95
  96 /* Generate code to evaluate EXP and jump to LABEL if the value is nonzero.  */
  97
  98 void
  99 jumpif (tree exp, rtx label)
 100 {
 101   do_jump (exp, NULL_RTX, label);
 102 }
 103
 104 /* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if
 105    the result is zero, or IF_TRUE_LABEL if the result is one.
 106    Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero,
 107    meaning fall through in that case.
 108
 109    do_jump always does any pending stack adjust except when it does not
 110    actually perform a jump.  An example where there is no jump
 111    is when EXP is `(foo (), 0)' and IF_FALSE_LABEL is null.
 112
 113    This function is responsible for optimizing cases such as
 114    &&, || and comparison operators in EXP.  */
 115
 116 void
 117 do_jump (tree exp, rtx if_false_label, rtx if_true_label)
 118 {
 119   enum tree_code code = TREE_CODE (exp);
 120   /* Some cases need to create a label to jump to
 121      in order to properly fall through.
 122      These cases set DROP_THROUGH_LABEL nonzero.  */
 123   rtx drop_through_label = 0;
 124   rtx temp;
 125   int i;
 126   tree type;
 127   enum machine_mode mode;
 128
 129   emit_queue ();
 130
 131   switch (code)
 132     {
 133     case ERROR_MARK:
 134       break;
 135
 136     case INTEGER_CST:
 137       temp = integer_zerop (exp) ? if_false_label : if_true_label;
 138       if (temp)
 139         emit_jump (temp);
 140       break;
 141
 142 #if 0
 143       /* This is not true with #pragma weak  */
 144     case ADDR_EXPR:
 145       /* The address of something can never be zero.  */
 146       if (if_true_label)
 147         emit_jump (if_true_label);
 148       break;
 149 #endif
 150
 151     case UNSAVE_EXPR:
 152       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 153       TREE_OPERAND (exp, 0)
 154         = (*lang_hooks.unsave_expr_now) (TREE_OPERAND (exp, 0));
 155       break;
 156
 157     case NOP_EXPR:
 158       if (TREE_CODE (TREE_OPERAND (exp, 0)) == COMPONENT_REF
 159           || TREE_CODE (TREE_OPERAND (exp, 0)) == BIT_FIELD_REF
 160           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF
 161           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_RANGE_REF)
 162         goto normal;
 163     case CONVERT_EXPR:
 164       /* If we are narrowing the operand, we have to do the compare in the
 165          narrower mode.  */
 166       if ((TYPE_PRECISION (TREE_TYPE (exp))
 167            < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
 168         goto normal;
 169     case NON_LVALUE_EXPR:
 170     case REFERENCE_EXPR:
 171     case ABS_EXPR:
 172     case NEGATE_EXPR:
 173     case LROTATE_EXPR:
 174     case RROTATE_EXPR:
 175       /* These cannot change zero->nonzero or vice versa.  */
 176       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 177       break;
 178
 179     case WITH_RECORD_EXPR:
 180       /* Put the object on the placeholder list, recurse through our first
 181          operand, and pop the list.  */
 182       placeholder_list = tree_cons (TREE_OPERAND (exp, 1), NULL_TREE,
 183                                     placeholder_list);
 184       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 185       placeholder_list = TREE_CHAIN (placeholder_list);
 186       break;
 187
 188 #if 0
 189       /* This is never less insns than evaluating the PLUS_EXPR followed by
 190          a test and can be longer if the test is eliminated.  */
 191     case PLUS_EXPR:
 192       /* Reduce to minus.  */
 193       exp = build (MINUS_EXPR, TREE_TYPE (exp),
 194                    TREE_OPERAND (exp, 0),
 195                    fold (build1 (NEGATE_EXPR, TREE_TYPE (TREE_OPERAND (exp, 1)),
 196                                  TREE_OPERAND (exp, 1))));
 197       /* Process as MINUS.  */
 198 #endif
 199
 200     case MINUS_EXPR:
 201       /* Nonzero iff operands of minus differ.  */
 202       do_compare_and_jump (build (NE_EXPR, TREE_TYPE (exp),
 203                                   TREE_OPERAND (exp, 0),
 204                                   TREE_OPERAND (exp, 1)),
 205                            NE, NE, if_false_label, if_true_label);
 206       break;
 207
 208     case BIT_AND_EXPR:
 209       /* If we are AND'ing with a small constant, do this comparison in the
 210          smallest type that fits.  If the machine doesn't have comparisons
 211          that small, it will be converted back to the wider comparison.
 212          This helps if we are testing the sign bit of a narrower object.
 213          combine can't do this for us because it can't know whether a
 214          ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */
 215
 216       if (! SLOW_BYTE_ACCESS
 217           && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
 218           && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT
 219           && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0
 220           && (mode = mode_for_size (i + 1, MODE_INT, 0)) != BLKmode
 221           && (type = (*lang_hooks.types.type_for_mode) (mode, 1)) != 0
 222           && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 223           && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 224               != CODE_FOR_nothing))
 225         {
 226           do_jump (convert (type, exp), if_false_label, if_true_label);
 227           break;
 228         }
 229       goto normal;
 230
 231     case TRUTH_NOT_EXPR:
 232       do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 233       break;
 234
 235     case TRUTH_ANDIF_EXPR:
 236       if (if_false_label == 0)
 237         if_false_label = drop_through_label = gen_label_rtx ();
 238       do_jump (TREE_OPERAND (exp, 0), if_false_label, NULL_RTX);
 239       start_cleanup_deferral ();
 240       do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 241       end_cleanup_deferral ();
 242       break;
 243
 244     case TRUTH_ORIF_EXPR:
 245       if (if_true_label == 0)
 246         if_true_label = drop_through_label = gen_label_rtx ();
 247       do_jump (TREE_OPERAND (exp, 0), NULL_RTX, if_true_label);
 248       start_cleanup_deferral ();
 249       do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 250       end_cleanup_deferral ();
 251       break;
 252
 253     case COMPOUND_EXPR:
 254       push_temp_slots ();
 255       expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, 0);
 256       preserve_temp_slots (NULL_RTX);
 257       free_temp_slots ();
 258       pop_temp_slots ();
 259       emit_queue ();
 260       do_pending_stack_adjust ();
 261       do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 262       break;
 263
 264     case COMPONENT_REF:
 265     case BIT_FIELD_REF:
 266     case ARRAY_REF:
 267     case ARRAY_RANGE_REF:
 268       {
 269         HOST_WIDE_INT bitsize, bitpos;
 270         int unsignedp;
 271         enum machine_mode mode;
 272         tree type;
 273         tree offset;
 274         int volatilep = 0;
 275
 276         /* Get description of this reference.  We don't actually care
 277            about the underlying object here.  */
 278         get_inner_reference (exp, &bitsize, &bitpos, &offset, &mode,
 279                              &unsignedp, &volatilep);
 280
 281         type = (*lang_hooks.types.type_for_size) (bitsize, unsignedp);
 282         if (! SLOW_BYTE_ACCESS
 283             && type != 0 && bitsize >= 0
 284             && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 285             && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 286           != CODE_FOR_nothing))
 287           {
 288             do_jump (convert (type, exp), if_false_label, if_true_label);
 289             break;
 290           }
 291         goto normal;
 292       }
 293
 294     case COND_EXPR:
 295       /* Do (a ? 1 : 0) and (a ? 0 : 1) as special cases.  */
 296       if (integer_onep (TREE_OPERAND (exp, 1))
 297           && integer_zerop (TREE_OPERAND (exp, 2)))
 298         do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 299
 300       else if (integer_zerop (TREE_OPERAND (exp, 1))
 301                && integer_onep (TREE_OPERAND (exp, 2)))
 302         do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 303
 304       else
 305       {
 306         rtx label1 = gen_label_rtx ();
 307         drop_through_label = gen_label_rtx ();
 308
 309         do_jump (TREE_OPERAND (exp, 0), label1, NULL_RTX);
 310
 311         start_cleanup_deferral ();
 312         /* Now the THEN-expression.  */
 313         do_jump (TREE_OPERAND (exp, 1),
 314                  if_false_label ? if_false_label : drop_through_label,
 315                  if_true_label ? if_true_label : drop_through_label);
 316         /* In case the do_jump just above never jumps.  */
 317         do_pending_stack_adjust ();
 318         emit_label (label1);
 319
 320         /* Now the ELSE-expression.  */
 321         do_jump (TREE_OPERAND (exp, 2),
 322            if_false_label ? if_false_label : drop_through_label,
 323            if_true_label ? if_true_label : drop_through_label);
 324         end_cleanup_deferral ();
 325       }
 326       break;
 327
 328     case EQ_EXPR:
 329       {
 330         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 331
 332         if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_FLOAT
 333             || GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_INT)
 334           {
 335             tree exp0 = save_expr (TREE_OPERAND (exp, 0));
 336             tree exp1 = save_expr (TREE_OPERAND (exp, 1));
 337             do_jump
 338               (fold
 339                (build (TRUTH_ANDIF_EXPR, TREE_TYPE (exp),
 340                  fold (build (EQ_EXPR, TREE_TYPE (exp),
 341                   fold (build1 (REALPART_EXPR,
 342                     TREE_TYPE (inner_type),
 343                     exp0)),
 344                   fold (build1 (REALPART_EXPR,
 345                     TREE_TYPE (inner_type),
 346                     exp1)))),
 347                  fold (build (EQ_EXPR, TREE_TYPE (exp),
 348                   fold (build1 (IMAGPART_EXPR,
 349                     TREE_TYPE (inner_type),
 350                     exp0)),
 351                   fold (build1 (IMAGPART_EXPR,
 352                     TREE_TYPE (inner_type),
 353                     exp1)))))),
 354                if_false_label, if_true_label);
 355           }
 356
 357         else if (integer_zerop (TREE_OPERAND (exp, 1)))
 358           do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 359
 360         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 361                  && !can_compare_p (EQ, TYPE_MODE (inner_type), ccp_jump))
 362           do_jump_by_parts_equality (exp, if_false_label, if_true_label);
 363         else
 364           do_compare_and_jump (exp, EQ, EQ, if_false_label, if_true_label);
 365         break;
 366       }
 367
 368     case NE_EXPR:
 369       {
 370         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 371
 372         if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_FLOAT
 373             || GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_INT)
 374           {
 375             tree exp0 = save_expr (TREE_OPERAND (exp, 0));
 376             tree exp1 = save_expr (TREE_OPERAND (exp, 1));
 377             do_jump
 378               (fold
 379                (build (TRUTH_ORIF_EXPR, TREE_TYPE (exp),
 380                  fold (build (NE_EXPR, TREE_TYPE (exp),
 381                   fold (build1 (REALPART_EXPR,
 382                     TREE_TYPE (inner_type),
 383                     exp0)),
 384                   fold (build1 (REALPART_EXPR,
 385                     TREE_TYPE (inner_type),
 386                     exp1)))),
 387                  fold (build (NE_EXPR, TREE_TYPE (exp),
 388                     fold (build1 (IMAGPART_EXPR,
 389                       TREE_TYPE (inner_type),
 390                       exp0)),
 391                     fold (build1 (IMAGPART_EXPR,
 392                       TREE_TYPE (inner_type),
 393                       exp1)))))),
 394                if_false_label, if_true_label);
 395           }
 396
 397         else if (integer_zerop (TREE_OPERAND (exp, 1)))
 398           do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 399
 400         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 401            && !can_compare_p (NE, TYPE_MODE (inner_type), ccp_jump))
 402           do_jump_by_parts_equality (exp, if_true_label, if_false_label);
 403         else
 404           do_compare_and_jump (exp, NE, NE, if_false_label, if_true_label);
 405         break;
 406       }
 407
 408     case LT_EXPR:
 409       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 410       if (GET_MODE_CLASS (mode) == MODE_INT
 411           && ! can_compare_p (LT, mode, ccp_jump))
 412         do_jump_by_parts_greater (exp, 1, if_false_label, if_true_label);
 413       else
 414         do_compare_and_jump (exp, LT, LTU, if_false_label, if_true_label);
 415       break;
 416
 417     case LE_EXPR:
 418       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 419       if (GET_MODE_CLASS (mode) == MODE_INT
 420           && ! can_compare_p (LE, mode, ccp_jump))
 421         do_jump_by_parts_greater (exp, 0, if_true_label, if_false_label);
 422       else
 423         do_compare_and_jump (exp, LE, LEU, if_false_label, if_true_label);
 424       break;
 425
 426     case GT_EXPR:
 427       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 428       if (GET_MODE_CLASS (mode) == MODE_INT
 429           && ! can_compare_p (GT, mode, ccp_jump))
 430         do_jump_by_parts_greater (exp, 0, if_false_label, if_true_label);
 431       else
 432         do_compare_and_jump (exp, GT, GTU, if_false_label, if_true_label);
 433       break;
 434
 435     case GE_EXPR:
 436       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 437       if (GET_MODE_CLASS (mode) == MODE_INT
 438           && ! can_compare_p (GE, mode, ccp_jump))
 439         do_jump_by_parts_greater (exp, 1, if_true_label, if_false_label);
 440       else
 441         do_compare_and_jump (exp, GE, GEU, if_false_label, if_true_label);
 442       break;
 443
 444     case UNORDERED_EXPR:
 445     case ORDERED_EXPR:
 446       {
 447         enum rtx_code cmp, rcmp;
 448         int do_rev;
 449
 450         if (code == UNORDERED_EXPR)
 451           cmp = UNORDERED, rcmp = ORDERED;
 452         else
 453           cmp = ORDERED, rcmp = UNORDERED;
 454         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 455
 456         do_rev = 0;
 457         if (! can_compare_p (cmp, mode, ccp_jump)
 458             && (can_compare_p (rcmp, mode, ccp_jump)
 459           /* If the target doesn't provide either UNORDERED or ORDERED
 460              comparisons, canonicalize on UNORDERED for the library.  */
 461           || rcmp == UNORDERED))
 462           do_rev = 1;
 463
 464         if (! do_rev)
 465           do_compare_and_jump (exp, cmp, cmp, if_false_label, if_true_label);
 466         else
 467           do_compare_and_jump (exp, rcmp, rcmp, if_true_label, if_false_label);
 468       }
 469       break;
 470
 471     {
 472       enum rtx_code rcode1;
 473       enum tree_code tcode2;
 474
 475       case UNLT_EXPR:
 476         rcode1 = UNLT;
 477         tcode2 = LT_EXPR;
 478         goto unordered_bcc;
 479       case UNLE_EXPR:
 480         rcode1 = UNLE;
 481         tcode2 = LE_EXPR;
 482         goto unordered_bcc;
 483       case UNGT_EXPR:
 484         rcode1 = UNGT;
 485         tcode2 = GT_EXPR;
 486         goto unordered_bcc;
 487       case UNGE_EXPR:
 488         rcode1 = UNGE;
 489         tcode2 = GE_EXPR;
 490         goto unordered_bcc;
 491       case UNEQ_EXPR:
 492         rcode1 = UNEQ;
 493         tcode2 = EQ_EXPR;
 494         goto unordered_bcc;
 495
 496       unordered_bcc:
 497         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 498         if (can_compare_p (rcode1, mode, ccp_jump))
 499           do_compare_and_jump (exp, rcode1, rcode1, if_false_label,
 500                                if_true_label);
 501         else
 502           {
 503             tree op0 = save_expr (TREE_OPERAND (exp, 0));
 504             tree op1 = save_expr (TREE_OPERAND (exp, 1));
 505             tree cmp0, cmp1;
 506
 507             /* If the target doesn't support combined unordered
 508                compares, decompose into UNORDERED + comparison.  */
 509             cmp0 = fold (build (UNORDERED_EXPR, TREE_TYPE (exp), op0, op1));
 510             cmp1 = fold (build (tcode2, TREE_TYPE (exp), op0, op1));
 511             exp = build (TRUTH_ORIF_EXPR, TREE_TYPE (exp), cmp0, cmp1);
 512             do_jump (exp, if_false_label, if_true_label);
 513           }
 514       }
 515       break;
 516
 517       /* Special case:
 518           __builtin_expect (<test>, 0)  and
 519           __builtin_expect (<test>, 1)
 520
 521          We need to do this here, so that <test> is not converted to a SCC
 522          operation on machines that use condition code registers and COMPARE
 523          like the PowerPC, and then the jump is done based on whether the SCC
 524          operation produced a 1 or 0.  */
 525     case CALL_EXPR:
 526       /* Check for a built-in function.  */
 527       {
 528         tree fndecl = get_callee_fndecl (exp);
 529         tree arglist = TREE_OPERAND (exp, 1);
 530
 531         if (fndecl
 532             && DECL_BUILT_IN (fndecl)
 533             && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT
 534             && arglist != NULL_TREE
 535             && TREE_CHAIN (arglist) != NULL_TREE)
 536           {
 537             rtx seq = expand_builtin_expect_jump (exp, if_false_label,
 538                                                   if_true_label);
 539
 540             if (seq != NULL_RTX)
 541               {
 542                 emit_insn (seq);
 543                 return;
 544               }
 545           }
 546       }
 547       /* Fall through and generate the normal code.  */
 548
 549     default:
 550     normal:
 551       temp = expand_expr (exp, NULL_RTX, VOIDmode, 0);
 552 #if 0
 553       /* This is not needed any more and causes poor code since it causes
 554          comparisons and tests from non-SI objects to have different code
 555          sequences.  */
 556       /* Copy to register to avoid generating bad insns by cse
 557          from (set (mem ...) (arithop))  (set (cc0) (mem ...)).  */
 558       if (!cse_not_expected && GET_CODE (temp) == MEM)
 559         temp = copy_to_reg (temp);
 560 #endif
 561       do_pending_stack_adjust ();
 562       /* Do any postincrements in the expression that was tested.  */
 563       emit_queue ();
 564
 565       if (GET_CODE (temp) == CONST_INT
 566           || (GET_CODE (temp) == CONST_DOUBLE && GET_MODE (temp) == VOIDmode)
 567           || GET_CODE (temp) == LABEL_REF)
 568         {
 569           rtx target = temp == const0_rtx ? if_false_label : if_true_label;
 570           if (target)
 571             emit_jump (target);
 572         }
 573       else if (GET_MODE_CLASS (GET_MODE (temp)) == MODE_INT
 574                && ! can_compare_p (NE, GET_MODE (temp), ccp_jump))
 575         /* Note swapping the labels gives us not-equal.  */
 576         do_jump_by_parts_equality_rtx (temp, if_true_label, if_false_label);
 577       else if (GET_MODE (temp) != VOIDmode)
 578         {
 579           /* The RTL optimizers prefer comparisons against pseudos.  */
 580           if (GET_CODE (temp) == SUBREG)
 581             {
 582               /* Compare promoted variables in their promoted mode.  */
 583               if (SUBREG_PROMOTED_VAR_P (temp)
 584                   && GET_CODE (XEXP (temp, 0)) == REG)
 585                 temp = XEXP (temp, 0);
 586               else
 587                 temp = copy_to_reg (temp);
 588             }
 589           do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),
 590                                    NE, TREE_UNSIGNED (TREE_TYPE (exp)),
 591                                    GET_MODE (temp), NULL_RTX,
 592                                    if_false_label, if_true_label);
 593         }
 594       else
 595         abort ();
 596     }
 597
 598   if (drop_through_label)
 599     {
 600       /* If do_jump produces code that might be jumped around,
 601          do any stack adjusts from that code, before the place
 602          where control merges in.  */
 603       do_pending_stack_adjust ();
 604       emit_label (drop_through_label);
 605     }
 606 }
 607 \f
 608 /* Given a comparison expression EXP for values too wide to be compared
 609    with one insn, test the comparison and jump to the appropriate label.
 610    The code of EXP is ignored; we always test GT if SWAP is 0,
 611    and LT if SWAP is 1.  */
 612
 613 static void
 614 do_jump_by_parts_greater (tree exp, int swap, rtx if_false_label,
 615                           rtx if_true_label)
 616 {
 617   rtx op0 = expand_expr (TREE_OPERAND (exp, swap), NULL_RTX, VOIDmode, 0);
 618   rtx op1 = expand_expr (TREE_OPERAND (exp, !swap), NULL_RTX, VOIDmode, 0);
 619   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 620   int unsignedp = TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)));
 621
 622   do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label, if_true_label);
 623 }
 624
 625 /* Compare OP0 with OP1, word at a time, in mode MODE.
 626    UNSIGNEDP says to do unsigned comparison.
 627    Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */
 628
 629 void
 630 do_jump_by_parts_greater_rtx (enum machine_mode mode, int unsignedp, rtx op0,
 631                               rtx op1, rtx if_false_label, rtx if_true_label)
 632 {
 633   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 634   rtx drop_through_label = 0;
 635   int i;
 636
 637   if (! if_true_label || ! if_false_label)
 638     drop_through_label = gen_label_rtx ();
 639   if (! if_true_label)
 640     if_true_label = drop_through_label;
 641   if (! if_false_label)
 642     if_false_label = drop_through_label;
 643
 644   /* Compare a word at a time, high order first.  */
 645   for (i = 0; i < nwords; i++)
 646     {
 647       rtx op0_word, op1_word;
 648
 649       if (WORDS_BIG_ENDIAN)
 650         {
 651           op0_word = operand_subword_force (op0, i, mode);
 652           op1_word = operand_subword_force (op1, i, mode);
 653         }
 654       else
 655         {
 656           op0_word = operand_subword_force (op0, nwords - 1 - i, mode);
 657           op1_word = operand_subword_force (op1, nwords - 1 - i, mode);
 658         }
 659
 660       /* All but high-order word must be compared as unsigned.  */
 661       do_compare_rtx_and_jump (op0_word, op1_word, GT,
 662                                (unsignedp || i > 0), word_mode, NULL_RTX,
 663                                NULL_RTX, if_true_label);
 664
 665       /* Consider lower words only if these are equal.  */
 666       do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,
 667                                NULL_RTX, NULL_RTX, if_false_label);
 668     }
 669
 670   if (if_false_label)
 671     emit_jump (if_false_label);
 672   if (drop_through_label)
 673     emit_label (drop_through_label);
 674 }
 675
 676 /* Given an EQ_EXPR expression EXP for values too wide to be compared
 677    with one insn, test the comparison and jump to the appropriate label.  */
 678
 679 static void
 680 do_jump_by_parts_equality (tree exp, rtx if_false_label, rtx if_true_label)
 681 {
 682   rtx op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
 683   rtx op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 684   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 685   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 686   int i;
 687   rtx drop_through_label = 0;
 688
 689   if (! if_false_label)
 690     drop_through_label = if_false_label = gen_label_rtx ();
 691
 692   for (i = 0; i < nwords; i++)
 693     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 694                              operand_subword_force (op1, i, mode),
 695                              EQ, TREE_UNSIGNED (TREE_TYPE (exp)),
 696                              word_mode, NULL_RTX, if_false_label, NULL_RTX);
 697
 698   if (if_true_label)
 699     emit_jump (if_true_label);
 700   if (drop_through_label)
 701     emit_label (drop_through_label);
 702 }
 703 \f
 704 /* Jump according to whether OP0 is 0.
 705    We assume that OP0 has an integer mode that is too wide
 706    for the available compare insns.  */
 707
 708 void
 709 do_jump_by_parts_equality_rtx (rtx op0, rtx if_false_label, rtx if_true_label)
 710 {
 711   int nwords = GET_MODE_SIZE (GET_MODE (op0)) / UNITS_PER_WORD;
 712   rtx part;
 713   int i;
 714   rtx drop_through_label = 0;
 715
 716   /* The fastest way of doing this comparison on almost any machine is to
 717      "or" all the words and compare the result.  If all have to be loaded
 718      from memory and this is a very wide item, it's possible this may
 719      be slower, but that's highly unlikely.  */
 720
 721   part = gen_reg_rtx (word_mode);
 722   emit_move_insn (part, operand_subword_force (op0, 0, GET_MODE (op0)));
 723   for (i = 1; i < nwords && part != 0; i++)
 724     part = expand_binop (word_mode, ior_optab, part,
 725                          operand_subword_force (op0, i, GET_MODE (op0)),
 726                          part, 1, OPTAB_WIDEN);
 727
 728   if (part != 0)
 729     {
 730       do_compare_rtx_and_jump (part, const0_rtx, EQ, 1, word_mode,
 731                                NULL_RTX, if_false_label, if_true_label);
 732
 733       return;
 734     }
 735
 736   /* If we couldn't do the "or" simply, do this with a series of compares.  */
 737   if (! if_false_label)
 738     drop_through_label = if_false_label = gen_label_rtx ();
 739
 740   for (i = 0; i < nwords; i++)
 741     do_compare_rtx_and_jump (operand_subword_force (op0, i, GET_MODE (op0)),
 742                              const0_rtx, EQ, 1, word_mode, NULL_RTX,
 743                              if_false_label, NULL_RTX);
 744
 745   if (if_true_label)
 746     emit_jump (if_true_label);
 747
 748   if (drop_through_label)
 749     emit_label (drop_through_label);
 750 }
 751 \f
 752 /* Generate code for a comparison of OP0 and OP1 with rtx code CODE.
 753    (including code to compute the values to be compared)
 754    and set (CC0) according to the result.
 755    The decision as to signed or unsigned comparison must be made by the caller.
 756
 757    We force a stack adjustment unless there are currently
 758    things pushed on the stack that aren't yet used.
 759
 760    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 761    compared.  */
 762
 763 rtx
 764 compare_from_rtx (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 765                   enum machine_mode mode, rtx size)
 766 {
 767   enum rtx_code ucode;
 768   rtx tem;
 769
 770   /* If one operand is constant, make it the second one.  Only do this
 771      if the other operand is not constant as well.  */
 772
 773   if (swap_commutative_operands_p (op0, op1))
 774     {
 775       tem = op0;
 776       op0 = op1;
 777       op1 = tem;
 778       code = swap_condition (code);
 779     }
 780
 781   if (flag_force_mem)
 782     {
 783       op0 = force_not_mem (op0);
 784       op1 = force_not_mem (op1);
 785     }
 786
 787   do_pending_stack_adjust ();
 788
 789   ucode = unsignedp ? unsigned_condition (code) : code;
 790   if ((tem = simplify_relational_operation (ucode, mode, op0, op1)) != 0)
 791     return tem;
 792
 793 #if 0
 794   /* There's no need to do this now that combine.c can eliminate lots of
 795      sign extensions.  This can be less efficient in certain cases on other
 796      machines.  */
 797
 798   /* If this is a signed equality comparison, we can do it as an
 799      unsigned comparison since zero-extension is cheaper than sign
 800      extension and comparisons with zero are done as unsigned.  This is
 801      the case even on machines that can do fast sign extension, since
 802      zero-extension is easier to combine with other operations than
 803      sign-extension is.  If we are comparing against a constant, we must
 804      convert it to what it would look like unsigned.  */
 805   if ((code == EQ || code == NE) && ! unsignedp
 806       && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT)
 807     {
 808       if (GET_CODE (op1) == CONST_INT
 809           && (INTVAL (op1) & GET_MODE_MASK (GET_MODE (op0))) != INTVAL (op1))
 810         op1 = GEN_INT (INTVAL (op1) & GET_MODE_MASK (GET_MODE (op0)));
 811       unsignedp = 1;
 812     }
 813 #endif
 814
 815   emit_cmp_insn (op0, op1, code, size, mode, unsignedp);
 816
 817 #if HAVE_cc0
 818   return gen_rtx_fmt_ee (code, VOIDmode, cc0_rtx, const0_rtx);
 819 #else
 820   return gen_rtx_fmt_ee (code, VOIDmode, op0, op1);
 821 #endif
 822 }
 823
 824 /* Like do_compare_and_jump but expects the values to compare as two rtx's.
 825    The decision as to signed or unsigned comparison must be made by the caller.
 826
 827    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 828    compared.  */
 829
 830 void
 831 do_compare_rtx_and_jump (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 832                          enum machine_mode mode, rtx size, rtx if_false_label,
 833                          rtx if_true_label)
 834 {
 835   enum rtx_code ucode;
 836   rtx tem;
 837   int dummy_true_label = 0;
 838
 839   /* Reverse the comparison if that is safe and we want to jump if it is
 840      false.  */
 841   if (! if_true_label && ! FLOAT_MODE_P (mode))
 842     {
 843       if_true_label = if_false_label;
 844       if_false_label = 0;
 845       code = reverse_condition (code);
 846     }
 847
 848   /* If one operand is constant, make it the second one.  Only do this
 849      if the other operand is not constant as well.  */
 850
 851   if (swap_commutative_operands_p (op0, op1))
 852     {
 853       tem = op0;
 854       op0 = op1;
 855       op1 = tem;
 856       code = swap_condition (code);
 857     }
 858
 859   if (flag_force_mem)
 860     {
 861       op0 = force_not_mem (op0);
 862       op1 = force_not_mem (op1);
 863     }
 864
 865   do_pending_stack_adjust ();
 866
 867   ucode = unsignedp ? unsigned_condition (code) : code;
 868   if ((tem = simplify_relational_operation (ucode, mode, op0, op1)) != 0)
 869     {
 870       if (tem == const_true_rtx)
 871         {
 872           if (if_true_label)
 873             emit_jump (if_true_label);
 874         }
 875       else
 876         {
 877           if (if_false_label)
 878             emit_jump (if_false_label);
 879         }
 880       return;
 881     }
 882
 883 #if 0
 884   /* There's no need to do this now that combine.c can eliminate lots of
 885      sign extensions.  This can be less efficient in certain cases on other
 886      machines.  */
 887
 888   /* If this is a signed equality comparison, we can do it as an
 889      unsigned comparison since zero-extension is cheaper than sign
 890      extension and comparisons with zero are done as unsigned.  This is
 891      the case even on machines that can do fast sign extension, since
 892      zero-extension is easier to combine with other operations than
 893      sign-extension is.  If we are comparing against a constant, we must
 894      convert it to what it would look like unsigned.  */
 895   if ((code == EQ || code == NE) && ! unsignedp
 896       && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT)
 897     {
 898       if (GET_CODE (op1) == CONST_INT
 899           && (INTVAL (op1) & GET_MODE_MASK (GET_MODE (op0))) != INTVAL (op1))
 900         op1 = GEN_INT (INTVAL (op1) & GET_MODE_MASK (GET_MODE (op0)));
 901       unsignedp = 1;
 902     }
 903 #endif
 904
 905   if (! if_true_label)
 906     {
 907       dummy_true_label = 1;
 908       if_true_label = gen_label_rtx ();
 909     }
 910
 911   emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp,
 912                            if_true_label);
 913
 914   if (if_false_label)
 915     emit_jump (if_false_label);
 916   if (dummy_true_label)
 917     emit_label (if_true_label);
 918 }
 919
 920 /* Generate code for a comparison expression EXP (including code to compute
 921    the values to be compared) and a conditional jump to IF_FALSE_LABEL and/or
 922    IF_TRUE_LABEL.  One of the labels can be NULL_RTX, in which case the
 923    generated code will drop through.
 924    SIGNED_CODE should be the rtx operation for this comparison for
 925    signed data; UNSIGNED_CODE, likewise for use if data is unsigned.
 926
 927    We force a stack adjustment unless there are currently
 928    things pushed on the stack that aren't yet used.  */
 929
 930 static void
 931 do_compare_and_jump (tree exp, enum rtx_code signed_code,
 932                      enum rtx_code unsigned_code, rtx if_false_label,
 933                      rtx if_true_label)
 934 {
 935   rtx op0, op1;
 936   tree type;
 937   enum machine_mode mode;
 938   int unsignedp;
 939   enum rtx_code code;
 940
 941   /* Don't crash if the comparison was erroneous.  */
 942   op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
 943   if (TREE_CODE (TREE_OPERAND (exp, 0)) == ERROR_MARK)
 944     return;
 945
 946   op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 947   if (TREE_CODE (TREE_OPERAND (exp, 1)) == ERROR_MARK)
 948     return;
 949
 950   type = TREE_TYPE (TREE_OPERAND (exp, 0));
 951   mode = TYPE_MODE (type);
 952   if (TREE_CODE (TREE_OPERAND (exp, 0)) == INTEGER_CST
 953       && (TREE_CODE (TREE_OPERAND (exp, 1)) != INTEGER_CST
 954           || (GET_MODE_BITSIZE (mode)
 955               > GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp,
 956                                                                       1)))))))
 957     {
 958       /* op0 might have been replaced by promoted constant, in which
 959          case the type of second argument should be used.  */
 960       type = TREE_TYPE (TREE_OPERAND (exp, 1));
 961       mode = TYPE_MODE (type);
 962     }
 963   unsignedp = TREE_UNSIGNED (type);
 964   code = unsignedp ? unsigned_code : signed_code;
 965
 966 #ifdef HAVE_canonicalize_funcptr_for_compare
 967   /* If function pointers need to be "canonicalized" before they can
 968      be reliably compared, then canonicalize them.  */
 969   if (HAVE_canonicalize_funcptr_for_compare
 970       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == POINTER_TYPE
 971       && (TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 0))))
 972           == FUNCTION_TYPE))
 973     {
 974       rtx new_op0 = gen_reg_rtx (mode);
 975
 976       emit_insn (gen_canonicalize_funcptr_for_compare (new_op0, op0));
 977       op0 = new_op0;
 978     }
 979
 980   if (HAVE_canonicalize_funcptr_for_compare
 981       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 1))) == POINTER_TYPE
 982       && (TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 1))))
 983           == FUNCTION_TYPE))
 984     {
 985       rtx new_op1 = gen_reg_rtx (mode);
 986
 987       emit_insn (gen_canonicalize_funcptr_for_compare (new_op1, op1));
 988       op1 = new_op1;
 989     }
 990 #endif
 991
 992   /* Do any postincrements in the expression that was tested.  */
 993   emit_queue ();
 994
 995   do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode,
 996                            ((mode == BLKmode)
 997                             ? expr_size (TREE_OPERAND (exp, 0)) : NULL_RTX),
 998                            if_false_label, if_true_label);
 999 }