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 MINUS_EXPR:
 211       /* Nonzero iff operands of minus differ.  */
 212       do_compare_and_jump (build2 (NE_EXPR, TREE_TYPE (exp),
 213                                    TREE_OPERAND (exp, 0),
 214                                    TREE_OPERAND (exp, 1)),
 215                            NE, NE, if_false_label, if_true_label);
 216       break;
 217
 218     case BIT_AND_EXPR:
 219       /* fold_single_bit_test() converts (X & (1 << C)) into (X >> C) & 1.
 220          See if the former is preferred for jump tests and restore it
 221          if so.  */
 222       if (integer_onep (TREE_OPERAND (exp, 1)))
 223         {
 224           tree exp0 = TREE_OPERAND (exp, 0);
 225           rtx set_label, clr_label;
 226
 227           /* Strip narrowing integral type conversions.  */
 228           while ((TREE_CODE (exp0) == NOP_EXPR
 229                   || TREE_CODE (exp0) == CONVERT_EXPR
 230                   || TREE_CODE (exp0) == NON_LVALUE_EXPR)
 231                  && TREE_OPERAND (exp0, 0) != error_mark_node
 232                  && TYPE_PRECISION (TREE_TYPE (exp0))
 233                     <= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp0, 0))))
 234             exp0 = TREE_OPERAND (exp0, 0);
 235
 236           /* "exp0 ^ 1" inverts the sense of the single bit test.  */
 237           if (TREE_CODE (exp0) == BIT_XOR_EXPR
 238               && integer_onep (TREE_OPERAND (exp0, 1)))
 239             {
 240               exp0 = TREE_OPERAND (exp0, 0);
 241               clr_label = if_true_label;
 242               set_label = if_false_label;
 243             }
 244           else
 245             {
 246               clr_label = if_false_label;
 247               set_label = if_true_label;
 248             }
 249
 250           if (TREE_CODE (exp0) == RSHIFT_EXPR)
 251             {
 252               tree arg = TREE_OPERAND (exp0, 0);
 253               tree shift = TREE_OPERAND (exp0, 1);
 254               tree argtype = TREE_TYPE (arg);
 255               if (TREE_CODE (shift) == INTEGER_CST
 256                   && compare_tree_int (shift, 0) >= 0
 257                   && compare_tree_int (shift, HOST_BITS_PER_WIDE_INT) < 0
 258                   && prefer_and_bit_test (TYPE_MODE (argtype),
 259                                           TREE_INT_CST_LOW (shift)))
 260                 {
 261                   HOST_WIDE_INT mask = (HOST_WIDE_INT) 1
 262                                        << TREE_INT_CST_LOW (shift);
 263                   do_jump (build2 (BIT_AND_EXPR, argtype, arg,
 264                                    build_int_cst_type (argtype, mask)),
 265                            clr_label, set_label);
 266                   break;
 267                 }
 268             }
 269         }
 270
 271       /* If we are AND'ing with a small constant, do this comparison in the
 272          smallest type that fits.  If the machine doesn't have comparisons
 273          that small, it will be converted back to the wider comparison.
 274          This helps if we are testing the sign bit of a narrower object.
 275          combine can't do this for us because it can't know whether a
 276          ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */
 277
 278       if (! SLOW_BYTE_ACCESS
 279           && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
 280           && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT
 281           && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0
 282           && (mode = mode_for_size (i + 1, MODE_INT, 0)) != BLKmode
 283           && (type = lang_hooks.types.type_for_mode (mode, 1)) != 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     case TRUTH_NOT_EXPR:
 294       do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 295       break;
 296
 297     case COND_EXPR:
 298       {
 299         rtx label1 = gen_label_rtx ();
 300         if (!if_true_label || !if_false_label)
 301           {
 302             drop_through_label = gen_label_rtx ();
 303             if (!if_true_label)
 304               if_true_label = drop_through_label;
 305             if (!if_false_label)
 306               if_false_label = drop_through_label;
 307           }
 308
 309         do_pending_stack_adjust ();
 310         do_jump (TREE_OPERAND (exp, 0), label1, NULL_RTX);
 311         do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 312         emit_label (label1);
 313         do_jump (TREE_OPERAND (exp, 2), if_false_label, if_true_label);
 314         break;
 315       }
 316
 317     case TRUTH_ANDIF_EXPR:
 318     case TRUTH_ORIF_EXPR:
 319     case COMPOUND_EXPR:
 320       /* Lowered by gimplify.c.  */
 321       gcc_unreachable ();
 322
 323     case COMPONENT_REF:
 324     case BIT_FIELD_REF:
 325     case ARRAY_REF:
 326     case ARRAY_RANGE_REF:
 327       {
 328         HOST_WIDE_INT bitsize, bitpos;
 329         int unsignedp;
 330         enum machine_mode mode;
 331         tree type;
 332         tree offset;
 333         int volatilep = 0;
 334
 335         /* Get description of this reference.  We don't actually care
 336            about the underlying object here.  */
 337         get_inner_reference (exp, &bitsize, &bitpos, &offset, &mode,
 338                              &unsignedp, &volatilep, false);
 339
 340         type = lang_hooks.types.type_for_size (bitsize, unsignedp);
 341         if (! SLOW_BYTE_ACCESS
 342             && type != 0 && bitsize >= 0
 343             && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 344             && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 345                 != CODE_FOR_nothing))
 346           {
 347             do_jump (convert (type, exp), if_false_label, if_true_label);
 348             break;
 349           }
 350         goto normal;
 351       }
 352
 353     case EQ_EXPR:
 354       {
 355         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 356
 357         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 358                     != MODE_COMPLEX_FLOAT);
 359         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 360                     != MODE_COMPLEX_INT);
 361
 362         if (integer_zerop (TREE_OPERAND (exp, 1)))
 363           do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 364         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 365                  && !can_compare_p (EQ, TYPE_MODE (inner_type), ccp_jump))
 366           do_jump_by_parts_equality (exp, if_false_label, if_true_label);
 367         else
 368           do_compare_and_jump (exp, EQ, EQ, if_false_label, if_true_label);
 369         break;
 370       }
 371
 372     case NE_EXPR:
 373       {
 374         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 375
 376         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 377                     != MODE_COMPLEX_FLOAT);
 378         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 379                     != MODE_COMPLEX_INT);
 380
 381         if (integer_zerop (TREE_OPERAND (exp, 1)))
 382           do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 383         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 384            && !can_compare_p (NE, TYPE_MODE (inner_type), ccp_jump))
 385           do_jump_by_parts_equality (exp, if_true_label, if_false_label);
 386         else
 387           do_compare_and_jump (exp, NE, NE, if_false_label, if_true_label);
 388         break;
 389       }
 390
 391     case LT_EXPR:
 392       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 393       if (GET_MODE_CLASS (mode) == MODE_INT
 394           && ! can_compare_p (LT, mode, ccp_jump))
 395         do_jump_by_parts_greater (exp, 1, if_false_label, if_true_label);
 396       else
 397         do_compare_and_jump (exp, LT, LTU, if_false_label, if_true_label);
 398       break;
 399
 400     case LE_EXPR:
 401       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 402       if (GET_MODE_CLASS (mode) == MODE_INT
 403           && ! can_compare_p (LE, mode, ccp_jump))
 404         do_jump_by_parts_greater (exp, 0, if_true_label, if_false_label);
 405       else
 406         do_compare_and_jump (exp, LE, LEU, if_false_label, if_true_label);
 407       break;
 408
 409     case GT_EXPR:
 410       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 411       if (GET_MODE_CLASS (mode) == MODE_INT
 412           && ! can_compare_p (GT, mode, ccp_jump))
 413         do_jump_by_parts_greater (exp, 0, if_false_label, if_true_label);
 414       else
 415         do_compare_and_jump (exp, GT, GTU, if_false_label, if_true_label);
 416       break;
 417
 418     case GE_EXPR:
 419       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 420       if (GET_MODE_CLASS (mode) == MODE_INT
 421           && ! can_compare_p (GE, mode, ccp_jump))
 422         do_jump_by_parts_greater (exp, 1, if_true_label, if_false_label);
 423       else
 424         do_compare_and_jump (exp, GE, GEU, if_false_label, if_true_label);
 425       break;
 426
 427     case UNORDERED_EXPR:
 428     case ORDERED_EXPR:
 429       {
 430         enum rtx_code cmp, rcmp;
 431         int do_rev;
 432
 433         if (code == UNORDERED_EXPR)
 434           cmp = UNORDERED, rcmp = ORDERED;
 435         else
 436           cmp = ORDERED, rcmp = UNORDERED;
 437         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 438
 439         do_rev = 0;
 440         if (! can_compare_p (cmp, mode, ccp_jump)
 441             && (can_compare_p (rcmp, mode, ccp_jump)
 442           /* If the target doesn't provide either UNORDERED or ORDERED
 443              comparisons, canonicalize on UNORDERED for the library.  */
 444           || rcmp == UNORDERED))
 445           do_rev = 1;
 446
 447         if (! do_rev)
 448           do_compare_and_jump (exp, cmp, cmp, if_false_label, if_true_label);
 449         else
 450           do_compare_and_jump (exp, rcmp, rcmp, if_true_label, if_false_label);
 451       }
 452       break;
 453
 454     {
 455       enum rtx_code rcode1;
 456       enum tree_code tcode1, tcode2;
 457
 458       case UNLT_EXPR:
 459         rcode1 = UNLT;
 460         tcode1 = UNORDERED_EXPR;
 461         tcode2 = LT_EXPR;
 462         goto unordered_bcc;
 463       case UNLE_EXPR:
 464         rcode1 = UNLE;
 465         tcode1 = UNORDERED_EXPR;
 466         tcode2 = LE_EXPR;
 467         goto unordered_bcc;
 468       case UNGT_EXPR:
 469         rcode1 = UNGT;
 470         tcode1 = UNORDERED_EXPR;
 471         tcode2 = GT_EXPR;
 472         goto unordered_bcc;
 473       case UNGE_EXPR:
 474         rcode1 = UNGE;
 475         tcode1 = UNORDERED_EXPR;
 476         tcode2 = GE_EXPR;
 477         goto unordered_bcc;
 478       case UNEQ_EXPR:
 479         rcode1 = UNEQ;
 480         tcode1 = UNORDERED_EXPR;
 481         tcode2 = EQ_EXPR;
 482         goto unordered_bcc;
 483       case LTGT_EXPR:
 484         /* It is ok for LTGT_EXPR to trap when the result is unordered,
 485            so expand to (a < b) || (a > b).  */
 486         rcode1 = LTGT;
 487         tcode1 = LT_EXPR;
 488         tcode2 = GT_EXPR;
 489         goto unordered_bcc;
 490
 491       unordered_bcc:
 492         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 493         if (can_compare_p (rcode1, mode, ccp_jump))
 494           do_compare_and_jump (exp, rcode1, rcode1, if_false_label,
 495                                if_true_label);
 496         else
 497           {
 498             tree op0 = save_expr (TREE_OPERAND (exp, 0));
 499             tree op1 = save_expr (TREE_OPERAND (exp, 1));
 500             tree cmp0, cmp1;
 501
 502             /* If the target doesn't support combined unordered
 503                compares, decompose into two comparisons.  */
 504             if (if_true_label == 0)
 505               drop_through_label = if_true_label = gen_label_rtx ();
 506
 507             cmp0 = fold (build2 (tcode1, TREE_TYPE (exp), op0, op1));
 508             cmp1 = fold (build2 (tcode2, TREE_TYPE (exp), op0, op1));
 509             do_jump (cmp0, 0, if_true_label);
 510             do_jump (cmp1, if_false_label, if_true_label);
 511           }
 512       }
 513       break;
 514
 515       /* Special case:
 516           __builtin_expect (<test>, 0)  and
 517           __builtin_expect (<test>, 1)
 518
 519          We need to do this here, so that <test> is not converted to a SCC
 520          operation on machines that use condition code registers and COMPARE
 521          like the PowerPC, and then the jump is done based on whether the SCC
 522          operation produced a 1 or 0.  */
 523     case CALL_EXPR:
 524       /* Check for a built-in function.  */
 525       {
 526         tree fndecl = get_callee_fndecl (exp);
 527         tree arglist = TREE_OPERAND (exp, 1);
 528
 529         if (fndecl
 530             && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
 531             && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT
 532             && arglist != NULL_TREE
 533             && TREE_CHAIN (arglist) != NULL_TREE)
 534           {
 535             rtx seq = expand_builtin_expect_jump (exp, if_false_label,
 536                                                   if_true_label);
 537
 538             if (seq != NULL_RTX)
 539               {
 540                 emit_insn (seq);
 541                 return;
 542               }
 543           }
 544       }
 545       /* Fall through and generate the normal code.  */
 546
 547     default:
 548     normal:
 549       temp = expand_expr (exp, NULL_RTX, VOIDmode, 0);
 550       do_pending_stack_adjust ();
 551
 552       if (GET_CODE (temp) == CONST_INT
 553           || (GET_CODE (temp) == CONST_DOUBLE && GET_MODE (temp) == VOIDmode)
 554           || GET_CODE (temp) == LABEL_REF)
 555         {
 556           rtx target = temp == const0_rtx ? if_false_label : if_true_label;
 557           if (target)
 558             emit_jump (target);
 559         }
 560       else if (GET_MODE_CLASS (GET_MODE (temp)) == MODE_INT
 561                && ! can_compare_p (NE, GET_MODE (temp), ccp_jump))
 562         /* Note swapping the labels gives us not-equal.  */
 563         do_jump_by_parts_equality_rtx (temp, if_true_label, if_false_label);
 564       else
 565         {
 566           gcc_assert (GET_MODE (temp) != VOIDmode);
 567
 568           /* The RTL optimizers prefer comparisons against pseudos.  */
 569           if (GET_CODE (temp) == SUBREG)
 570             {
 571               /* Compare promoted variables in their promoted mode.  */
 572               if (SUBREG_PROMOTED_VAR_P (temp)
 573                   && REG_P (XEXP (temp, 0)))
 574                 temp = XEXP (temp, 0);
 575               else
 576                 temp = copy_to_reg (temp);
 577             }
 578           do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),
 579                                    NE, TYPE_UNSIGNED (TREE_TYPE (exp)),
 580                                    GET_MODE (temp), NULL_RTX,
 581                                    if_false_label, if_true_label);
 582         }
 583     }
 584
 585   if (drop_through_label)
 586     {
 587       do_pending_stack_adjust ();
 588       emit_label (drop_through_label);
 589     }
 590 }
 591 \f
 592 /* Given a comparison expression EXP for values too wide to be compared
 593    with one insn, test the comparison and jump to the appropriate label.
 594    The code of EXP is ignored; we always test GT if SWAP is 0,
 595    and LT if SWAP is 1.  */
 596
 597 static void
 598 do_jump_by_parts_greater (tree exp, int swap, rtx if_false_label,
 599                           rtx if_true_label)
 600 {
 601   rtx op0 = expand_expr (TREE_OPERAND (exp, swap), NULL_RTX, VOIDmode, 0);
 602   rtx op1 = expand_expr (TREE_OPERAND (exp, !swap), NULL_RTX, VOIDmode, 0);
 603   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 604   int unsignedp = TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)));
 605
 606   do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label,
 607                                 if_true_label);
 608 }
 609
 610 /* Compare OP0 with OP1, word at a time, in mode MODE.
 611    UNSIGNEDP says to do unsigned comparison.
 612    Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */
 613
 614 void
 615 do_jump_by_parts_greater_rtx (enum machine_mode mode, int unsignedp, rtx op0,
 616                               rtx op1, rtx if_false_label, rtx if_true_label)
 617 {
 618   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 619   rtx drop_through_label = 0;
 620   int i;
 621
 622   if (! if_true_label || ! if_false_label)
 623     drop_through_label = gen_label_rtx ();
 624   if (! if_true_label)
 625     if_true_label = drop_through_label;
 626   if (! if_false_label)
 627     if_false_label = drop_through_label;
 628
 629   /* Compare a word at a time, high order first.  */
 630   for (i = 0; i < nwords; i++)
 631     {
 632       rtx op0_word, op1_word;
 633
 634       if (WORDS_BIG_ENDIAN)
 635         {
 636           op0_word = operand_subword_force (op0, i, mode);
 637           op1_word = operand_subword_force (op1, i, mode);
 638         }
 639       else
 640         {
 641           op0_word = operand_subword_force (op0, nwords - 1 - i, mode);
 642           op1_word = operand_subword_force (op1, nwords - 1 - i, mode);
 643         }
 644
 645       /* All but high-order word must be compared as unsigned.  */
 646       do_compare_rtx_and_jump (op0_word, op1_word, GT,
 647                                (unsignedp || i > 0), word_mode, NULL_RTX,
 648                                NULL_RTX, if_true_label);
 649
 650       /* Consider lower words only if these are equal.  */
 651       do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,
 652                                NULL_RTX, NULL_RTX, if_false_label);
 653     }
 654
 655   if (if_false_label)
 656     emit_jump (if_false_label);
 657   if (drop_through_label)
 658     emit_label (drop_through_label);
 659 }
 660
 661 /* Given an EQ_EXPR expression EXP for values too wide to be compared
 662    with one insn, test the comparison and jump to the appropriate label.  */
 663
 664 static void
 665 do_jump_by_parts_equality (tree exp, rtx if_false_label, rtx if_true_label)
 666 {
 667   rtx op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
 668   rtx op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 669   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 670   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 671   int i;
 672   rtx drop_through_label = 0;
 673
 674   if (! if_false_label)
 675     drop_through_label = if_false_label = gen_label_rtx ();
 676
 677   for (i = 0; i < nwords; i++)
 678     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 679                              operand_subword_force (op1, i, mode),
 680                              EQ, TYPE_UNSIGNED (TREE_TYPE (exp)),
 681                              word_mode, NULL_RTX, if_false_label, NULL_RTX);
 682
 683   if (if_true_label)
 684     emit_jump (if_true_label);
 685   if (drop_through_label)
 686     emit_label (drop_through_label);
 687 }
 688 \f
 689 /* Jump according to whether OP0 is 0.
 690    We assume that OP0 has an integer mode that is too wide
 691    for the available compare insns.  */
 692
 693 void
 694 do_jump_by_parts_equality_rtx (rtx op0, rtx if_false_label, rtx if_true_label)
 695 {
 696   int nwords = GET_MODE_SIZE (GET_MODE (op0)) / UNITS_PER_WORD;
 697   rtx part;
 698   int i;
 699   rtx drop_through_label = 0;
 700
 701   /* The fastest way of doing this comparison on almost any machine is to
 702      "or" all the words and compare the result.  If all have to be loaded
 703      from memory and this is a very wide item, it's possible this may
 704      be slower, but that's highly unlikely.  */
 705
 706   part = gen_reg_rtx (word_mode);
 707   emit_move_insn (part, operand_subword_force (op0, 0, GET_MODE (op0)));
 708   for (i = 1; i < nwords && part != 0; i++)
 709     part = expand_binop (word_mode, ior_optab, part,
 710                          operand_subword_force (op0, i, GET_MODE (op0)),
 711                          part, 1, OPTAB_WIDEN);
 712
 713   if (part != 0)
 714     {
 715       do_compare_rtx_and_jump (part, const0_rtx, EQ, 1, word_mode,
 716                                NULL_RTX, if_false_label, if_true_label);
 717
 718       return;
 719     }
 720
 721   /* If we couldn't do the "or" simply, do this with a series of compares.  */
 722   if (! if_false_label)
 723     drop_through_label = if_false_label = gen_label_rtx ();
 724
 725   for (i = 0; i < nwords; i++)
 726     do_compare_rtx_and_jump (operand_subword_force (op0, i, GET_MODE (op0)),
 727                              const0_rtx, EQ, 1, word_mode, NULL_RTX,
 728                              if_false_label, NULL_RTX);
 729
 730   if (if_true_label)
 731     emit_jump (if_true_label);
 732
 733   if (drop_through_label)
 734     emit_label (drop_through_label);
 735 }
 736 \f
 737 /* Generate code for a comparison of OP0 and OP1 with rtx code CODE.
 738    MODE is the machine mode of the comparison, not of the result.
 739    (including code to compute the values to be compared) and set CC0
 740    according to the result.  The decision as to signed or unsigned
 741    comparison must be made by the caller.
 742
 743    We force a stack adjustment unless there are currently
 744    things pushed on the stack that aren't yet used.
 745
 746    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 747    compared.  */
 748
 749 rtx
 750 compare_from_rtx (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 751                   enum machine_mode mode, rtx size)
 752 {
 753   rtx tem;
 754
 755   /* If one operand is constant, make it the second one.  Only do this
 756      if the other operand is not constant as well.  */
 757
 758   if (swap_commutative_operands_p (op0, op1))
 759     {
 760       tem = op0;
 761       op0 = op1;
 762       op1 = tem;
 763       code = swap_condition (code);
 764     }
 765
 766   if (flag_force_mem)
 767     {
 768       op0 = force_not_mem (op0);
 769       op1 = force_not_mem (op1);
 770     }
 771
 772   do_pending_stack_adjust ();
 773
 774   code = unsignedp ? unsigned_condition (code) : code;
 775   tem = simplify_relational_operation (code, VOIDmode, mode, op0, op1);
 776   if (tem)
 777     {
 778       if (CONSTANT_P (tem))
 779         return tem;
 780
 781       if (COMPARISON_P (tem))
 782         {
 783           code = GET_CODE (tem);
 784           op0 = XEXP (tem, 0);
 785           op1 = XEXP (tem, 1);
 786           mode = GET_MODE (op0);
 787           unsignedp = (code == GTU || code == LTU
 788                        || code == GEU || code == LEU);
 789         }
 790     }
 791
 792   emit_cmp_insn (op0, op1, code, size, mode, unsignedp);
 793
 794 #if HAVE_cc0
 795   return gen_rtx_fmt_ee (code, VOIDmode, cc0_rtx, const0_rtx);
 796 #else
 797   return gen_rtx_fmt_ee (code, VOIDmode, op0, op1);
 798 #endif
 799 }
 800
 801 /* Like do_compare_and_jump but expects the values to compare as two rtx's.
 802    The decision as to signed or unsigned comparison must be made by the caller.
 803
 804    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 805    compared.  */
 806
 807 void
 808 do_compare_rtx_and_jump (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 809                          enum machine_mode mode, rtx size, rtx if_false_label,
 810                          rtx if_true_label)
 811 {
 812   rtx tem;
 813   int dummy_true_label = 0;
 814
 815   /* Reverse the comparison if that is safe and we want to jump if it is
 816      false.  */
 817   if (! if_true_label && ! FLOAT_MODE_P (mode))
 818     {
 819       if_true_label = if_false_label;
 820       if_false_label = 0;
 821       code = reverse_condition (code);
 822     }
 823
 824   /* If one operand is constant, make it the second one.  Only do this
 825      if the other operand is not constant as well.  */
 826
 827   if (swap_commutative_operands_p (op0, op1))
 828     {
 829       tem = op0;
 830       op0 = op1;
 831       op1 = tem;
 832       code = swap_condition (code);
 833     }
 834
 835   if (flag_force_mem)
 836     {
 837       op0 = force_not_mem (op0);
 838       op1 = force_not_mem (op1);
 839     }
 840
 841   do_pending_stack_adjust ();
 842
 843   code = unsignedp ? unsigned_condition (code) : code;
 844   if (0 != (tem = simplify_relational_operation (code, mode, VOIDmode,
 845                                                  op0, op1)))
 846     {
 847       if (CONSTANT_P (tem))
 848         {
 849           rtx label = (tem == const0_rtx || tem == CONST0_RTX (mode))
 850                       ? if_false_label : if_true_label;
 851           if (label)
 852             emit_jump (label);
 853           return;
 854         }
 855
 856       code = GET_CODE (tem);
 857       mode = GET_MODE (tem);
 858       op0 = XEXP (tem, 0);
 859       op1 = XEXP (tem, 1);
 860       unsignedp = (code == GTU || code == LTU || code == GEU || code == LEU);
 861     }
 862
 863   if (! if_true_label)
 864     {
 865       dummy_true_label = 1;
 866       if_true_label = gen_label_rtx ();
 867     }
 868
 869   emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp,
 870                            if_true_label);
 871
 872   if (if_false_label)
 873     emit_jump (if_false_label);
 874   if (dummy_true_label)
 875     emit_label (if_true_label);
 876 }
 877
 878 /* Generate code for a comparison expression EXP (including code to compute
 879    the values to be compared) and a conditional jump to IF_FALSE_LABEL and/or
 880    IF_TRUE_LABEL.  One of the labels can be NULL_RTX, in which case the
 881    generated code will drop through.
 882    SIGNED_CODE should be the rtx operation for this comparison for
 883    signed data; UNSIGNED_CODE, likewise for use if data is unsigned.
 884
 885    We force a stack adjustment unless there are currently
 886    things pushed on the stack that aren't yet used.  */
 887
 888 static void
 889 do_compare_and_jump (tree exp, enum rtx_code signed_code,
 890                      enum rtx_code unsigned_code, rtx if_false_label,
 891                      rtx if_true_label)
 892 {
 893   rtx op0, op1;
 894   tree type;
 895   enum machine_mode mode;
 896   int unsignedp;
 897   enum rtx_code code;
 898
 899   /* Don't crash if the comparison was erroneous.  */
 900   op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
 901   if (TREE_CODE (TREE_OPERAND (exp, 0)) == ERROR_MARK)
 902     return;
 903
 904   op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 905   if (TREE_CODE (TREE_OPERAND (exp, 1)) == ERROR_MARK)
 906     return;
 907
 908   type = TREE_TYPE (TREE_OPERAND (exp, 0));
 909   mode = TYPE_MODE (type);
 910   if (TREE_CODE (TREE_OPERAND (exp, 0)) == INTEGER_CST
 911       && (TREE_CODE (TREE_OPERAND (exp, 1)) != INTEGER_CST
 912           || (GET_MODE_BITSIZE (mode)
 913               > GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp,
 914                                                                       1)))))))
 915     {
 916       /* op0 might have been replaced by promoted constant, in which
 917          case the type of second argument should be used.  */
 918       type = TREE_TYPE (TREE_OPERAND (exp, 1));
 919       mode = TYPE_MODE (type);
 920     }
 921   unsignedp = TYPE_UNSIGNED (type);
 922   code = unsignedp ? unsigned_code : signed_code;
 923
 924 #ifdef HAVE_canonicalize_funcptr_for_compare
 925   /* If function pointers need to be "canonicalized" before they can
 926      be reliably compared, then canonicalize them.
 927      Only do this if *both* sides of the comparison are function pointers.
 928      If one side isn't, we want a noncanonicalized comparison.  See PR
 929      middle-end/17564.  */
 930   if (HAVE_canonicalize_funcptr_for_compare
 931       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == POINTER_TYPE
 932       && TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 0))))
 933           == FUNCTION_TYPE
 934       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 1))) == POINTER_TYPE
 935       && TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 1))))
 936           == FUNCTION_TYPE)
 937     {
 938       rtx new_op0 = gen_reg_rtx (mode);
 939       rtx new_op1 = gen_reg_rtx (mode);
 940
 941       emit_insn (gen_canonicalize_funcptr_for_compare (new_op0, op0));
 942       op0 = new_op0;
 943
 944       emit_insn (gen_canonicalize_funcptr_for_compare (new_op1, op1));
 945       op1 = new_op1;
 946     }
 947 #endif
 948
 949   do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode,
 950                            ((mode == BLKmode)
 951                             ? expr_size (TREE_OPERAND (exp, 0)) : NULL_RTX),
 952                            if_false_label, if_true_label);
 953 }
 954
 955 #include "gt-dojump.h"