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, 2006 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, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "rtl.h"
  27 #include "tree.h"
  28 #include "flags.h"
  29 #include "function.h"
  30 #include "insn-config.h"
  31 #include "insn-attr.h"
  32 /* Include expr.h after insn-config.h so we get HAVE_conditional_move.  */
  33 #include "expr.h"
  34 #include "optabs.h"
  35 #include "langhooks.h"
  36 #include "ggc.h"
  37
  38 static bool prefer_and_bit_test (enum machine_mode, int);
  39 static void do_jump_by_parts_greater (tree, int, rtx, rtx);
  40 static void do_jump_by_parts_equality (tree, rtx, rtx);
  41 static void do_compare_and_jump (tree, enum rtx_code, enum rtx_code, rtx,
  42                                  rtx);
  43
  44 /* At the start of a function, record that we have no previously-pushed
  45    arguments waiting to be popped.  */
  46
  47 void
  48 init_pending_stack_adjust (void)
  49 {
  50   pending_stack_adjust = 0;
  51 }
  52
  53 /* Discard any pending stack adjustment.  This avoid relying on the
  54    RTL optimizers to remove useless adjustments when we know the
  55    stack pointer value is dead.  */
  56 void discard_pending_stack_adjust (void)
  57 {
  58   stack_pointer_delta -= pending_stack_adjust;
  59   pending_stack_adjust = 0;
  60 }
  61
  62 /* When exiting from function, if safe, clear out any pending stack adjust
  63    so the adjustment won't get done.
  64
  65    Note, if the current function calls alloca, then it must have a
  66    frame pointer regardless of the value of flag_omit_frame_pointer.  */
  67
  68 void
  69 clear_pending_stack_adjust (void)
  70 {
  71   if (optimize > 0
  72       && (! flag_omit_frame_pointer || current_function_calls_alloca)
  73       && EXIT_IGNORE_STACK
  74       && ! (DECL_INLINE (current_function_decl) && ! flag_no_inline))
  75     discard_pending_stack_adjust ();
  76 }
  77
  78 /* Pop any previously-pushed arguments that have not been popped yet.  */
  79
  80 void
  81 do_pending_stack_adjust (void)
  82 {
  83   if (inhibit_defer_pop == 0)
  84     {
  85       if (pending_stack_adjust != 0)
  86         adjust_stack (GEN_INT (pending_stack_adjust));
  87       pending_stack_adjust = 0;
  88     }
  89 }
  90 \f
  91 /* Expand conditional expressions.  */
  92
  93 /* Generate code to evaluate EXP and jump to LABEL if the value is zero.
  94    LABEL is an rtx of code CODE_LABEL, in this function and all the
  95    functions here.  */
  96
  97 void
  98 jumpifnot (tree exp, rtx label)
  99 {
 100   do_jump (exp, label, NULL_RTX);
 101 }
 102
 103 /* Generate code to evaluate EXP and jump to LABEL if the value is nonzero.  */
 104
 105 void
 106 jumpif (tree exp, rtx label)
 107 {
 108   do_jump (exp, NULL_RTX, label);
 109 }
 110
 111 /* Used internally by prefer_and_bit_test.  */
 112
 113 static GTY(()) rtx and_reg;
 114 static GTY(()) rtx and_test;
 115 static GTY(()) rtx shift_test;
 116
 117 /* Compare the relative costs of "(X & (1 << BITNUM))" and "(X >> BITNUM) & 1",
 118    where X is an arbitrary register of mode MODE.  Return true if the former
 119    is preferred.  */
 120
 121 static bool
 122 prefer_and_bit_test (enum machine_mode mode, int bitnum)
 123 {
 124   if (and_test == 0)
 125     {
 126       /* Set up rtxes for the two variations.  Use NULL as a placeholder
 127          for the BITNUM-based constants.  */
 128       and_reg = gen_rtx_REG (mode, FIRST_PSEUDO_REGISTER);
 129       and_test = gen_rtx_AND (mode, and_reg, NULL);
 130       shift_test = gen_rtx_AND (mode, gen_rtx_ASHIFTRT (mode, and_reg, NULL),
 131                                 const1_rtx);
 132     }
 133   else
 134     {
 135       /* Change the mode of the previously-created rtxes.  */
 136       PUT_MODE (and_reg, mode);
 137       PUT_MODE (and_test, mode);
 138       PUT_MODE (shift_test, mode);
 139       PUT_MODE (XEXP (shift_test, 0), mode);
 140     }
 141
 142   /* Fill in the integers.  */
 143   XEXP (and_test, 1) = GEN_INT ((unsigned HOST_WIDE_INT) 1 << bitnum);
 144   XEXP (XEXP (shift_test, 0), 1) = GEN_INT (bitnum);
 145
 146   return (rtx_cost (and_test, IF_THEN_ELSE)
 147           <= rtx_cost (shift_test, IF_THEN_ELSE));
 148 }
 149
 150 /* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if
 151    the result is zero, or IF_TRUE_LABEL if the result is one.
 152    Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero,
 153    meaning fall through in that case.
 154
 155    do_jump always does any pending stack adjust except when it does not
 156    actually perform a jump.  An example where there is no jump
 157    is when EXP is `(foo (), 0)' and IF_FALSE_LABEL is null.  */
 158
 159 void
 160 do_jump (tree exp, rtx if_false_label, rtx if_true_label)
 161 {
 162   enum tree_code code = TREE_CODE (exp);
 163   rtx temp;
 164   int i;
 165   tree type;
 166   enum machine_mode mode;
 167   rtx drop_through_label = 0;
 168
 169   switch (code)
 170     {
 171     case ERROR_MARK:
 172       break;
 173
 174     case INTEGER_CST:
 175       temp = integer_zerop (exp) ? if_false_label : if_true_label;
 176       if (temp)
 177         emit_jump (temp);
 178       break;
 179
 180 #if 0
 181       /* This is not true with #pragma weak  */
 182     case ADDR_EXPR:
 183       /* The address of something can never be zero.  */
 184       if (if_true_label)
 185         emit_jump (if_true_label);
 186       break;
 187 #endif
 188
 189     case NOP_EXPR:
 190       if (TREE_CODE (TREE_OPERAND (exp, 0)) == COMPONENT_REF
 191           || TREE_CODE (TREE_OPERAND (exp, 0)) == BIT_FIELD_REF
 192           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF
 193           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_RANGE_REF)
 194         goto normal;
 195     case CONVERT_EXPR:
 196       /* If we are narrowing the operand, we have to do the compare in the
 197          narrower mode.  */
 198       if ((TYPE_PRECISION (TREE_TYPE (exp))
 199            < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
 200         goto normal;
 201     case NON_LVALUE_EXPR:
 202     case ABS_EXPR:
 203     case NEGATE_EXPR:
 204     case LROTATE_EXPR:
 205     case RROTATE_EXPR:
 206       /* These cannot change zero->nonzero or vice versa.  */
 207       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 208       break;
 209
 210     case BIT_AND_EXPR:
 211       /* fold_single_bit_test() converts (X & (1 << C)) into (X >> C) & 1.
 212          See if the former is preferred for jump tests and restore it
 213          if so.  */
 214       if (integer_onep (TREE_OPERAND (exp, 1)))
 215         {
 216           tree exp0 = TREE_OPERAND (exp, 0);
 217           rtx set_label, clr_label;
 218
 219           /* Strip narrowing integral type conversions.  */
 220           while ((TREE_CODE (exp0) == NOP_EXPR
 221                   || TREE_CODE (exp0) == CONVERT_EXPR
 222                   || TREE_CODE (exp0) == NON_LVALUE_EXPR)
 223                  && TREE_OPERAND (exp0, 0) != error_mark_node
 224                  && TYPE_PRECISION (TREE_TYPE (exp0))
 225                     <= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp0, 0))))
 226             exp0 = TREE_OPERAND (exp0, 0);
 227
 228           /* "exp0 ^ 1" inverts the sense of the single bit test.  */
 229           if (TREE_CODE (exp0) == BIT_XOR_EXPR
 230               && integer_onep (TREE_OPERAND (exp0, 1)))
 231             {
 232               exp0 = TREE_OPERAND (exp0, 0);
 233               clr_label = if_true_label;
 234               set_label = if_false_label;
 235             }
 236           else
 237             {
 238               clr_label = if_false_label;
 239               set_label = if_true_label;
 240             }
 241
 242           if (TREE_CODE (exp0) == RSHIFT_EXPR)
 243             {
 244               tree arg = TREE_OPERAND (exp0, 0);
 245               tree shift = TREE_OPERAND (exp0, 1);
 246               tree argtype = TREE_TYPE (arg);
 247               if (TREE_CODE (shift) == INTEGER_CST
 248                   && compare_tree_int (shift, 0) >= 0
 249                   && compare_tree_int (shift, HOST_BITS_PER_WIDE_INT) < 0
 250                   && prefer_and_bit_test (TYPE_MODE (argtype),
 251                                           TREE_INT_CST_LOW (shift)))
 252                 {
 253                   HOST_WIDE_INT mask = (HOST_WIDE_INT) 1
 254                                        << TREE_INT_CST_LOW (shift);
 255                   do_jump (build2 (BIT_AND_EXPR, argtype, arg,
 256                                    build_int_cst_type (argtype, mask)),
 257                            clr_label, set_label);
 258                   break;
 259                 }
 260             }
 261         }
 262
 263       /* If we are AND'ing with a small constant, do this comparison in the
 264          smallest type that fits.  If the machine doesn't have comparisons
 265          that small, it will be converted back to the wider comparison.
 266          This helps if we are testing the sign bit of a narrower object.
 267          combine can't do this for us because it can't know whether a
 268          ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */
 269
 270       if (! SLOW_BYTE_ACCESS
 271           && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
 272           && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT
 273           && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0
 274           && (mode = mode_for_size (i + 1, MODE_INT, 0)) != BLKmode
 275           && (type = lang_hooks.types.type_for_mode (mode, 1)) != 0
 276           && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 277           && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 278               != CODE_FOR_nothing))
 279         {
 280           do_jump (fold_convert (type, exp), if_false_label, if_true_label);
 281           break;
 282         }
 283       goto normal;
 284
 285     case TRUTH_NOT_EXPR:
 286       do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 287       break;
 288
 289     case COND_EXPR:
 290       {
 291         rtx label1 = gen_label_rtx ();
 292         if (!if_true_label || !if_false_label)
 293           {
 294             drop_through_label = gen_label_rtx ();
 295             if (!if_true_label)
 296               if_true_label = drop_through_label;
 297             if (!if_false_label)
 298               if_false_label = drop_through_label;
 299           }
 300
 301         do_pending_stack_adjust ();
 302         do_jump (TREE_OPERAND (exp, 0), label1, NULL_RTX);
 303         do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 304         emit_label (label1);
 305         do_jump (TREE_OPERAND (exp, 2), if_false_label, if_true_label);
 306         break;
 307       }
 308
 309     case TRUTH_ANDIF_EXPR:
 310     case TRUTH_ORIF_EXPR:
 311     case COMPOUND_EXPR:
 312       /* Lowered by gimplify.c.  */
 313       gcc_unreachable ();
 314
 315     case COMPONENT_REF:
 316     case BIT_FIELD_REF:
 317     case ARRAY_REF:
 318     case ARRAY_RANGE_REF:
 319       {
 320         HOST_WIDE_INT bitsize, bitpos;
 321         int unsignedp;
 322         enum machine_mode mode;
 323         tree type;
 324         tree offset;
 325         int volatilep = 0;
 326
 327         /* Get description of this reference.  We don't actually care
 328            about the underlying object here.  */
 329         get_inner_reference (exp, &bitsize, &bitpos, &offset, &mode,
 330                              &unsignedp, &volatilep, false);
 331
 332         type = lang_hooks.types.type_for_size (bitsize, unsignedp);
 333         if (! SLOW_BYTE_ACCESS
 334             && type != 0 && bitsize >= 0
 335             && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 336             && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
 337                 != CODE_FOR_nothing))
 338           {
 339             do_jump (fold_convert (type, exp), if_false_label, if_true_label);
 340             break;
 341           }
 342         goto normal;
 343       }
 344
 345     case EQ_EXPR:
 346       {
 347         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 348
 349         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 350                     != MODE_COMPLEX_FLOAT);
 351         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 352                     != MODE_COMPLEX_INT);
 353
 354         if (integer_zerop (TREE_OPERAND (exp, 1)))
 355           do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
 356         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 357                  && !can_compare_p (EQ, TYPE_MODE (inner_type), ccp_jump))
 358           do_jump_by_parts_equality (exp, if_false_label, if_true_label);
 359         else
 360           do_compare_and_jump (exp, EQ, EQ, if_false_label, if_true_label);
 361         break;
 362       }
 363
 364     case MINUS_EXPR:
 365       /* Nonzero iff operands of minus differ.  */
 366       exp = build2 (NE_EXPR, TREE_TYPE (exp),
 367                     TREE_OPERAND (exp, 0),
 368                     TREE_OPERAND (exp, 1));
 369       /* FALLTHRU */
 370     case NE_EXPR:
 371       {
 372         tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
 373
 374         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 375                     != MODE_COMPLEX_FLOAT);
 376         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 377                     != MODE_COMPLEX_INT);
 378
 379         if (integer_zerop (TREE_OPERAND (exp, 1)))
 380           do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
 381         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 382            && !can_compare_p (NE, TYPE_MODE (inner_type), ccp_jump))
 383           do_jump_by_parts_equality (exp, if_true_label, if_false_label);
 384         else
 385           do_compare_and_jump (exp, NE, NE, if_false_label, if_true_label);
 386         break;
 387       }
 388
 389     case LT_EXPR:
 390       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 391       if (GET_MODE_CLASS (mode) == MODE_INT
 392           && ! can_compare_p (LT, mode, ccp_jump))
 393         do_jump_by_parts_greater (exp, 1, if_false_label, if_true_label);
 394       else
 395         do_compare_and_jump (exp, LT, LTU, if_false_label, if_true_label);
 396       break;
 397
 398     case LE_EXPR:
 399       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 400       if (GET_MODE_CLASS (mode) == MODE_INT
 401           && ! can_compare_p (LE, mode, ccp_jump))
 402         do_jump_by_parts_greater (exp, 0, if_true_label, if_false_label);
 403       else
 404         do_compare_and_jump (exp, LE, LEU, if_false_label, if_true_label);
 405       break;
 406
 407     case GT_EXPR:
 408       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 409       if (GET_MODE_CLASS (mode) == MODE_INT
 410           && ! can_compare_p (GT, mode, ccp_jump))
 411         do_jump_by_parts_greater (exp, 0, if_false_label, if_true_label);
 412       else
 413         do_compare_and_jump (exp, GT, GTU, if_false_label, if_true_label);
 414       break;
 415
 416     case GE_EXPR:
 417       mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 418       if (GET_MODE_CLASS (mode) == MODE_INT
 419           && ! can_compare_p (GE, mode, ccp_jump))
 420         do_jump_by_parts_greater (exp, 1, if_true_label, if_false_label);
 421       else
 422         do_compare_and_jump (exp, GE, GEU, if_false_label, if_true_label);
 423       break;
 424
 425     case UNORDERED_EXPR:
 426     case ORDERED_EXPR:
 427       {
 428         enum rtx_code cmp, rcmp;
 429         int do_rev;
 430
 431         if (code == UNORDERED_EXPR)
 432           cmp = UNORDERED, rcmp = ORDERED;
 433         else
 434           cmp = ORDERED, rcmp = UNORDERED;
 435         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 436
 437         do_rev = 0;
 438         if (! can_compare_p (cmp, mode, ccp_jump)
 439             && (can_compare_p (rcmp, mode, ccp_jump)
 440           /* If the target doesn't provide either UNORDERED or ORDERED
 441              comparisons, canonicalize on UNORDERED for the library.  */
 442           || rcmp == UNORDERED))
 443           do_rev = 1;
 444
 445         if (! do_rev)
 446           do_compare_and_jump (exp, cmp, cmp, if_false_label, if_true_label);
 447         else
 448           do_compare_and_jump (exp, rcmp, rcmp, if_true_label, if_false_label);
 449       }
 450       break;
 451
 452     {
 453       enum rtx_code rcode1;
 454       enum tree_code tcode1, tcode2;
 455
 456       case UNLT_EXPR:
 457         rcode1 = UNLT;
 458         tcode1 = UNORDERED_EXPR;
 459         tcode2 = LT_EXPR;
 460         goto unordered_bcc;
 461       case UNLE_EXPR:
 462         rcode1 = UNLE;
 463         tcode1 = UNORDERED_EXPR;
 464         tcode2 = LE_EXPR;
 465         goto unordered_bcc;
 466       case UNGT_EXPR:
 467         rcode1 = UNGT;
 468         tcode1 = UNORDERED_EXPR;
 469         tcode2 = GT_EXPR;
 470         goto unordered_bcc;
 471       case UNGE_EXPR:
 472         rcode1 = UNGE;
 473         tcode1 = UNORDERED_EXPR;
 474         tcode2 = GE_EXPR;
 475         goto unordered_bcc;
 476       case UNEQ_EXPR:
 477         rcode1 = UNEQ;
 478         tcode1 = UNORDERED_EXPR;
 479         tcode2 = EQ_EXPR;
 480         goto unordered_bcc;
 481       case LTGT_EXPR:
 482         /* It is ok for LTGT_EXPR to trap when the result is unordered,
 483            so expand to (a < b) || (a > b).  */
 484         rcode1 = LTGT;
 485         tcode1 = LT_EXPR;
 486         tcode2 = GT_EXPR;
 487         goto unordered_bcc;
 488
 489       unordered_bcc:
 490         mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 491         if (can_compare_p (rcode1, mode, ccp_jump))
 492           do_compare_and_jump (exp, rcode1, rcode1, if_false_label,
 493                                if_true_label);
 494         else
 495           {
 496             tree op0 = save_expr (TREE_OPERAND (exp, 0));
 497             tree op1 = save_expr (TREE_OPERAND (exp, 1));
 498             tree cmp0, cmp1;
 499
 500             /* If the target doesn't support combined unordered
 501                compares, decompose into two comparisons.  */
 502             if (if_true_label == 0)
 503               drop_through_label = if_true_label = gen_label_rtx ();
 504
 505             cmp0 = fold_build2 (tcode1, TREE_TYPE (exp), op0, op1);
 506             cmp1 = fold_build2 (tcode2, TREE_TYPE (exp), op0, op1);
 507             do_jump (cmp0, 0, if_true_label);
 508             do_jump (cmp1, if_false_label, if_true_label);
 509           }
 510       }
 511       break;
 512
 513     case TRUTH_AND_EXPR:
 514       /* High branch cost, expand as the bitwise AND of the conditions.
 515          Do the same if the RHS has side effects, because we're effectively
 516          turning a TRUTH_AND_EXPR into a TRUTH_ANDIF_EXPR.  */
 517       if (BRANCH_COST >= 4 || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))
 518         goto normal;
 519
 520       if (if_false_label == NULL_RTX)
 521         {
 522           drop_through_label = gen_label_rtx ();
 523           do_jump (TREE_OPERAND (exp, 0), drop_through_label, NULL_RTX);
 524           do_jump (TREE_OPERAND (exp, 1), NULL_RTX, if_true_label);
 525         }
 526       else
 527         {
 528           do_jump (TREE_OPERAND (exp, 0), if_false_label, NULL_RTX);
 529           do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 530         }
 531       break;
 532
 533     case TRUTH_OR_EXPR:
 534       /* High branch cost, expand as the bitwise OR of the conditions.
 535          Do the same if the RHS has side effects, because we're effectively
 536          turning a TRUTH_OR_EXPR into a TRUTH_ORIF_EXPR.  */
 537       if (BRANCH_COST >= 4 || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))
 538         goto normal;
 539
 540       if (if_true_label == NULL_RTX)
 541         {
 542           drop_through_label = gen_label_rtx ();
 543           do_jump (TREE_OPERAND (exp, 0), NULL_RTX, drop_through_label);
 544           do_jump (TREE_OPERAND (exp, 1), if_false_label, NULL_RTX);
 545         }
 546       else
 547         {
 548           do_jump (TREE_OPERAND (exp, 0), NULL_RTX, if_true_label);
 549           do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
 550         }
 551       break;
 552
 553       /* Special case:
 554           __builtin_expect (<test>, 0)  and
 555           __builtin_expect (<test>, 1)
 556
 557          We need to do this here, so that <test> is not converted to a SCC
 558          operation on machines that use condition code registers and COMPARE
 559          like the PowerPC, and then the jump is done based on whether the SCC
 560          operation produced a 1 or 0.  */
 561     case CALL_EXPR:
 562       /* Check for a built-in function.  */
 563       {
 564         tree fndecl = get_callee_fndecl (exp);
 565         tree arglist = TREE_OPERAND (exp, 1);
 566
 567         if (fndecl
 568             && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
 569             && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT
 570             && arglist != NULL_TREE
 571             && TREE_CHAIN (arglist) != NULL_TREE)
 572           {
 573             rtx seq = expand_builtin_expect_jump (exp, if_false_label,
 574                                                   if_true_label);
 575
 576             if (seq != NULL_RTX)
 577               {
 578                 emit_insn (seq);
 579                 return;
 580               }
 581           }
 582       }
 583
 584       /* Fall through and generate the normal code.  */
 585     default:
 586     normal:
 587       temp = expand_normal (exp);
 588       do_pending_stack_adjust ();
 589       /* The RTL optimizers prefer comparisons against pseudos.  */
 590       if (GET_CODE (temp) == SUBREG)
 591         {
 592           /* Compare promoted variables in their promoted mode.  */
 593           if (SUBREG_PROMOTED_VAR_P (temp)
 594               && REG_P (XEXP (temp, 0)))
 595             temp = XEXP (temp, 0);
 596           else
 597             temp = copy_to_reg (temp);
 598         }
 599       do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),
 600                                NE, TYPE_UNSIGNED (TREE_TYPE (exp)),
 601                                GET_MODE (temp), NULL_RTX,
 602                                if_false_label, if_true_label);
 603     }
 604
 605   if (drop_through_label)
 606     {
 607       do_pending_stack_adjust ();
 608       emit_label (drop_through_label);
 609     }
 610 }
 611 \f
 612 /* Compare OP0 with OP1, word at a time, in mode MODE.
 613    UNSIGNEDP says to do unsigned comparison.
 614    Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */
 615
 616 static void
 617 do_jump_by_parts_greater_rtx (enum machine_mode mode, int unsignedp, rtx op0,
 618                               rtx op1, rtx if_false_label, rtx if_true_label)
 619 {
 620   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 621   rtx drop_through_label = 0;
 622   int i;
 623
 624   if (! if_true_label || ! if_false_label)
 625     drop_through_label = gen_label_rtx ();
 626   if (! if_true_label)
 627     if_true_label = drop_through_label;
 628   if (! if_false_label)
 629     if_false_label = drop_through_label;
 630
 631   /* Compare a word at a time, high order first.  */
 632   for (i = 0; i < nwords; i++)
 633     {
 634       rtx op0_word, op1_word;
 635
 636       if (WORDS_BIG_ENDIAN)
 637         {
 638           op0_word = operand_subword_force (op0, i, mode);
 639           op1_word = operand_subword_force (op1, i, mode);
 640         }
 641       else
 642         {
 643           op0_word = operand_subword_force (op0, nwords - 1 - i, mode);
 644           op1_word = operand_subword_force (op1, nwords - 1 - i, mode);
 645         }
 646
 647       /* All but high-order word must be compared as unsigned.  */
 648       do_compare_rtx_and_jump (op0_word, op1_word, GT,
 649                                (unsignedp || i > 0), word_mode, NULL_RTX,
 650                                NULL_RTX, if_true_label);
 651
 652       /* Consider lower words only if these are equal.  */
 653       do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,
 654                                NULL_RTX, NULL_RTX, if_false_label);
 655     }
 656
 657   if (if_false_label)
 658     emit_jump (if_false_label);
 659   if (drop_through_label)
 660     emit_label (drop_through_label);
 661 }
 662
 663 /* Given a comparison expression EXP for values too wide to be compared
 664    with one insn, test the comparison and jump to the appropriate label.
 665    The code of EXP is ignored; we always test GT if SWAP is 0,
 666    and LT if SWAP is 1.  */
 667
 668 static void
 669 do_jump_by_parts_greater (tree exp, int swap, rtx if_false_label,
 670                           rtx if_true_label)
 671 {
 672   rtx op0 = expand_normal (TREE_OPERAND (exp, swap));
 673   rtx op1 = expand_normal (TREE_OPERAND (exp, !swap));
 674   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 675   int unsignedp = TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)));
 676
 677   do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label,
 678                                 if_true_label);
 679 }
 680 \f
 681 /* Jump according to whether OP0 is 0.  We assume that OP0 has an integer
 682    mode, MODE, that is too wide for the available compare insns.  Either
 683    Either (but not both) of IF_TRUE_LABEL and IF_FALSE_LABEL may be NULL_RTX
 684    to indicate drop through.  */
 685
 686 static void
 687 do_jump_by_parts_zero_rtx (enum machine_mode mode, rtx op0,
 688                            rtx if_false_label, rtx if_true_label)
 689 {
 690   int nwords = GET_MODE_SIZE (mode) / UNITS_PER_WORD;
 691   rtx part;
 692   int i;
 693   rtx drop_through_label = 0;
 694
 695   /* The fastest way of doing this comparison on almost any machine is to
 696      "or" all the words and compare the result.  If all have to be loaded
 697      from memory and this is a very wide item, it's possible this may
 698      be slower, but that's highly unlikely.  */
 699
 700   part = gen_reg_rtx (word_mode);
 701   emit_move_insn (part, operand_subword_force (op0, 0, GET_MODE (op0)));
 702   for (i = 1; i < nwords && part != 0; i++)
 703     part = expand_binop (word_mode, ior_optab, part,
 704                          operand_subword_force (op0, i, GET_MODE (op0)),
 705                          part, 1, OPTAB_WIDEN);
 706
 707   if (part != 0)
 708     {
 709       do_compare_rtx_and_jump (part, const0_rtx, EQ, 1, word_mode,
 710                                NULL_RTX, if_false_label, if_true_label);
 711
 712       return;
 713     }
 714
 715   /* If we couldn't do the "or" simply, do this with a series of compares.  */
 716   if (! if_false_label)
 717     drop_through_label = if_false_label = gen_label_rtx ();
 718
 719   for (i = 0; i < nwords; i++)
 720     do_compare_rtx_and_jump (operand_subword_force (op0, i, GET_MODE (op0)),
 721                              const0_rtx, EQ, 1, word_mode, NULL_RTX,
 722                              if_false_label, NULL_RTX);
 723
 724   if (if_true_label)
 725     emit_jump (if_true_label);
 726
 727   if (drop_through_label)
 728     emit_label (drop_through_label);
 729 }
 730
 731 /* Test for the equality of two RTX expressions OP0 and OP1 in mode MODE,
 732    where MODE is an integer mode too wide to be compared with one insn.
 733    Either (but not both) of IF_TRUE_LABEL and IF_FALSE_LABEL may be NULL_RTX
 734    to indicate drop through.  */
 735
 736 static void
 737 do_jump_by_parts_equality_rtx (enum machine_mode mode, rtx op0, rtx op1,
 738                                rtx if_false_label, rtx if_true_label)
 739 {
 740   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 741   rtx drop_through_label = 0;
 742   int i;
 743
 744   if (op1 == const0_rtx)
 745     {
 746       do_jump_by_parts_zero_rtx (mode, op0, if_false_label, if_true_label);
 747       return;
 748     }
 749   else if (op0 == const0_rtx)
 750     {
 751       do_jump_by_parts_zero_rtx (mode, op1, if_false_label, if_true_label);
 752       return;
 753     }
 754
 755   if (! if_false_label)
 756     drop_through_label = if_false_label = gen_label_rtx ();
 757
 758   for (i = 0; i < nwords; i++)
 759     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 760                              operand_subword_force (op1, i, mode),
 761                              EQ, 0, word_mode, NULL_RTX,
 762                              if_false_label, NULL_RTX);
 763
 764   if (if_true_label)
 765     emit_jump (if_true_label);
 766   if (drop_through_label)
 767     emit_label (drop_through_label);
 768 }
 769
 770 /* Given an EQ_EXPR expression EXP for values too wide to be compared
 771    with one insn, test the comparison and jump to the appropriate label.  */
 772
 773 static void
 774 do_jump_by_parts_equality (tree exp, rtx if_false_label, rtx if_true_label)
 775 {
 776   rtx op0 = expand_normal (TREE_OPERAND (exp, 0));
 777   rtx op1 = expand_normal (TREE_OPERAND (exp, 1));
 778   enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 779   do_jump_by_parts_equality_rtx (mode, op0, op1, if_false_label,
 780                                  if_true_label);
 781 }
 782 \f
 783 /* Generate code for a comparison of OP0 and OP1 with rtx code CODE.
 784    MODE is the machine mode of the comparison, not of the result.
 785    (including code to compute the values to be compared) and set CC0
 786    according to the result.  The decision as to signed or unsigned
 787    comparison must be made by the caller.
 788
 789    We force a stack adjustment unless there are currently
 790    things pushed on the stack that aren't yet used.
 791
 792    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 793    compared.  */
 794
 795 rtx
 796 compare_from_rtx (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 797                   enum machine_mode mode, rtx size)
 798 {
 799   rtx tem;
 800
 801   /* If one operand is constant, make it the second one.  Only do this
 802      if the other operand is not constant as well.  */
 803
 804   if (swap_commutative_operands_p (op0, op1))
 805     {
 806       tem = op0;
 807       op0 = op1;
 808       op1 = tem;
 809       code = swap_condition (code);
 810     }
 811
 812   do_pending_stack_adjust ();
 813
 814   code = unsignedp ? unsigned_condition (code) : code;
 815   tem = simplify_relational_operation (code, VOIDmode, mode, op0, op1);
 816   if (tem)
 817     {
 818       if (CONSTANT_P (tem))
 819         return tem;
 820
 821       if (COMPARISON_P (tem))
 822         {
 823           code = GET_CODE (tem);
 824           op0 = XEXP (tem, 0);
 825           op1 = XEXP (tem, 1);
 826           mode = GET_MODE (op0);
 827           unsignedp = (code == GTU || code == LTU
 828                        || code == GEU || code == LEU);
 829         }
 830     }
 831
 832   emit_cmp_insn (op0, op1, code, size, mode, unsignedp);
 833
 834 #if HAVE_cc0
 835   return gen_rtx_fmt_ee (code, VOIDmode, cc0_rtx, const0_rtx);
 836 #else
 837   return gen_rtx_fmt_ee (code, VOIDmode, op0, op1);
 838 #endif
 839 }
 840
 841 /* Like do_compare_and_jump but expects the values to compare as two rtx's.
 842    The decision as to signed or unsigned comparison must be made by the caller.
 843
 844    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 845    compared.  */
 846
 847 void
 848 do_compare_rtx_and_jump (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 849                          enum machine_mode mode, rtx size, rtx if_false_label,
 850                          rtx if_true_label)
 851 {
 852   rtx tem;
 853   int dummy_true_label = 0;
 854
 855   /* Reverse the comparison if that is safe and we want to jump if it is
 856      false.  */
 857   if (! if_true_label && ! FLOAT_MODE_P (mode))
 858     {
 859       if_true_label = if_false_label;
 860       if_false_label = 0;
 861       code = reverse_condition (code);
 862     }
 863
 864   /* If one operand is constant, make it the second one.  Only do this
 865      if the other operand is not constant as well.  */
 866
 867   if (swap_commutative_operands_p (op0, op1))
 868     {
 869       tem = op0;
 870       op0 = op1;
 871       op1 = tem;
 872       code = swap_condition (code);
 873     }
 874
 875   do_pending_stack_adjust ();
 876
 877   code = unsignedp ? unsigned_condition (code) : code;
 878   if (0 != (tem = simplify_relational_operation (code, mode, VOIDmode,
 879                                                  op0, op1)))
 880     {
 881       if (CONSTANT_P (tem))
 882         {
 883           rtx label = (tem == const0_rtx || tem == CONST0_RTX (mode))
 884                       ? if_false_label : if_true_label;
 885           if (label)
 886             emit_jump (label);
 887           return;
 888         }
 889
 890       code = GET_CODE (tem);
 891       mode = GET_MODE (tem);
 892       op0 = XEXP (tem, 0);
 893       op1 = XEXP (tem, 1);
 894       unsignedp = (code == GTU || code == LTU || code == GEU || code == LEU);
 895     }
 896
 897
 898   if (! if_true_label)
 899     {
 900       dummy_true_label = 1;
 901       if_true_label = gen_label_rtx ();
 902     }
 903
 904   if (GET_MODE_CLASS (mode) == MODE_INT
 905       && ! can_compare_p (code, mode, ccp_jump))
 906     {
 907       switch (code)
 908         {
 909         case LTU:
 910           do_jump_by_parts_greater_rtx (mode, 1, op1, op0,
 911                                         if_false_label, if_true_label);
 912           break;
 913
 914         case LEU:
 915           do_jump_by_parts_greater_rtx (mode, 1, op0, op1,
 916                                         if_true_label, if_false_label);
 917           break;
 918
 919         case GTU:
 920           do_jump_by_parts_greater_rtx (mode, 1, op0, op1,
 921                                         if_false_label, if_true_label);
 922           break;
 923
 924         case GEU:
 925           do_jump_by_parts_greater_rtx (mode, 1, op1, op0,
 926                                         if_true_label, if_false_label);
 927           break;
 928
 929         case LT:
 930           do_jump_by_parts_greater_rtx (mode, 0, op1, op0,
 931                                         if_false_label, if_true_label);
 932           break;
 933
 934         case LE:
 935           do_jump_by_parts_greater_rtx (mode, 0, op0, op1,
 936                                         if_true_label, if_false_label);
 937           break;
 938
 939         case GT:
 940           do_jump_by_parts_greater_rtx (mode, 0, op0, op1,
 941                                         if_false_label, if_true_label);
 942           break;
 943
 944         case GE:
 945           do_jump_by_parts_greater_rtx (mode, 0, op1, op0,
 946                                         if_true_label, if_false_label);
 947           break;
 948
 949         case EQ:
 950           do_jump_by_parts_equality_rtx (mode, op0, op1, if_false_label,
 951                                          if_true_label);
 952           break;
 953
 954         case NE:
 955           do_jump_by_parts_equality_rtx (mode, op0, op1, if_true_label,
 956                                          if_false_label);
 957           break;
 958
 959         default:
 960           gcc_unreachable ();
 961         }
 962     }
 963   else
 964     emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp,
 965                              if_true_label);
 966
 967   if (if_false_label)
 968     emit_jump (if_false_label);
 969   if (dummy_true_label)
 970     emit_label (if_true_label);
 971 }
 972
 973 /* Generate code for a comparison expression EXP (including code to compute
 974    the values to be compared) and a conditional jump to IF_FALSE_LABEL and/or
 975    IF_TRUE_LABEL.  One of the labels can be NULL_RTX, in which case the
 976    generated code will drop through.
 977    SIGNED_CODE should be the rtx operation for this comparison for
 978    signed data; UNSIGNED_CODE, likewise for use if data is unsigned.
 979
 980    We force a stack adjustment unless there are currently
 981    things pushed on the stack that aren't yet used.  */
 982
 983 static void
 984 do_compare_and_jump (tree exp, enum rtx_code signed_code,
 985                      enum rtx_code unsigned_code, rtx if_false_label,
 986                      rtx if_true_label)
 987 {
 988   rtx op0, op1;
 989   tree type;
 990   enum machine_mode mode;
 991   int unsignedp;
 992   enum rtx_code code;
 993
 994   /* Don't crash if the comparison was erroneous.  */
 995   op0 = expand_normal (TREE_OPERAND (exp, 0));
 996   if (TREE_CODE (TREE_OPERAND (exp, 0)) == ERROR_MARK)
 997     return;
 998
 999   op1 = expand_normal (TREE_OPERAND (exp, 1));
1000   if (TREE_CODE (TREE_OPERAND (exp, 1)) == ERROR_MARK)
1001     return;
1002
1003   type = TREE_TYPE (TREE_OPERAND (exp, 0));
1004   mode = TYPE_MODE (type);
1005   if (TREE_CODE (TREE_OPERAND (exp, 0)) == INTEGER_CST
1006       && (TREE_CODE (TREE_OPERAND (exp, 1)) != INTEGER_CST
1007           || (GET_MODE_BITSIZE (mode)
1008               > GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp,
1009                                                                       1)))))))
1010     {
1011       /* op0 might have been replaced by promoted constant, in which
1012          case the type of second argument should be used.  */
1013       type = TREE_TYPE (TREE_OPERAND (exp, 1));
1014       mode = TYPE_MODE (type);
1015     }
1016   unsignedp = TYPE_UNSIGNED (type);
1017   code = unsignedp ? unsigned_code : signed_code;
1018
1019 #ifdef HAVE_canonicalize_funcptr_for_compare
1020   /* If function pointers need to be "canonicalized" before they can
1021      be reliably compared, then canonicalize them.
1022      Only do this if *both* sides of the comparison are function pointers.
1023      If one side isn't, we want a noncanonicalized comparison.  See PR
1024      middle-end/17564.  */
1025   if (HAVE_canonicalize_funcptr_for_compare
1026       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == POINTER_TYPE
1027       && TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 0))))
1028           == FUNCTION_TYPE
1029       && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 1))) == POINTER_TYPE
1030       && TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 1))))
1031           == FUNCTION_TYPE)
1032     {
1033       rtx new_op0 = gen_reg_rtx (mode);
1034       rtx new_op1 = gen_reg_rtx (mode);
1035
1036       emit_insn (gen_canonicalize_funcptr_for_compare (new_op0, op0));
1037       op0 = new_op0;
1038
1039       emit_insn (gen_canonicalize_funcptr_for_compare (new_op1, op1));
1040       op1 = new_op1;
1041     }
1042 #endif
1043
1044   do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode,
1045                            ((mode == BLKmode)
1046                             ? expr_size (TREE_OPERAND (exp, 0)) : NULL_RTX),
1047                            if_false_label, if_true_label);
1048 }
1049
1050 #include "gt-dojump.h"