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, 2007, 2008, 2009, 2010
   4    Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  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 #include "basic-block.h"
  38 #include "output.h"
  39 #include "tm_p.h"
  40
  41 static bool prefer_and_bit_test (enum machine_mode, int);
  42 static void do_jump_by_parts_greater (tree, tree, int, rtx, rtx, int);
  43 static void do_jump_by_parts_equality (tree, tree, rtx, rtx, int);
  44 static void do_compare_and_jump (tree, tree, enum rtx_code, enum rtx_code, rtx,
  45                                  rtx, int);
  46
  47 /* Invert probability if there is any.  -1 stands for unknown.  */
  48
  49 static inline int
  50 inv (int prob)
  51 {
  52   return prob == -1 ? -1 : REG_BR_PROB_BASE - prob;
  53 }
  54
  55 /* At the start of a function, record that we have no previously-pushed
  56    arguments waiting to be popped.  */
  57
  58 void
  59 init_pending_stack_adjust (void)
  60 {
  61   pending_stack_adjust = 0;
  62 }
  63
  64 /* Discard any pending stack adjustment.  This avoid relying on the
  65    RTL optimizers to remove useless adjustments when we know the
  66    stack pointer value is dead.  */
  67 void
  68 discard_pending_stack_adjust (void)
  69 {
  70   stack_pointer_delta -= pending_stack_adjust;
  71   pending_stack_adjust = 0;
  72 }
  73
  74 /* When exiting from function, if safe, clear out any pending stack adjust
  75    so the adjustment won't get done.
  76
  77    Note, if the current function calls alloca, then it must have a
  78    frame pointer regardless of the value of flag_omit_frame_pointer.  */
  79
  80 void
  81 clear_pending_stack_adjust (void)
  82 {
  83   if (optimize > 0
  84       && (! flag_omit_frame_pointer || cfun->calls_alloca)
  85       && EXIT_IGNORE_STACK)
  86     discard_pending_stack_adjust ();
  87 }
  88
  89 /* Pop any previously-pushed arguments that have not been popped yet.  */
  90
  91 void
  92 do_pending_stack_adjust (void)
  93 {
  94   if (inhibit_defer_pop == 0)
  95     {
  96       if (pending_stack_adjust != 0)
  97         adjust_stack (GEN_INT (pending_stack_adjust));
  98       pending_stack_adjust = 0;
  99     }
 100 }
 101 \f
 102 /* Expand conditional expressions.  */
 103
 104 /* Generate code to evaluate EXP and jump to LABEL if the value is zero.
 105    LABEL is an rtx of code CODE_LABEL, in this function and all the
 106    functions here.  */
 107
 108 void
 109 jumpifnot (tree exp, rtx label, int prob)
 110 {
 111   do_jump (exp, label, NULL_RTX, inv (prob));
 112 }
 113
 114 void
 115 jumpifnot_1 (enum tree_code code, tree op0, tree op1, rtx label, int prob)
 116 {
 117   do_jump_1 (code, op0, op1, label, NULL_RTX, inv (prob));
 118 }
 119
 120 /* Generate code to evaluate EXP and jump to LABEL if the value is nonzero.  */
 121
 122 void
 123 jumpif (tree exp, rtx label, int prob)
 124 {
 125   do_jump (exp, NULL_RTX, label, prob);
 126 }
 127
 128 void
 129 jumpif_1 (enum tree_code code, tree op0, tree op1, rtx label, int prob)
 130 {
 131   do_jump_1 (code, op0, op1, NULL_RTX, label, prob);
 132 }
 133
 134 /* Used internally by prefer_and_bit_test.  */
 135
 136 static GTY(()) rtx and_reg;
 137 static GTY(()) rtx and_test;
 138 static GTY(()) rtx shift_test;
 139
 140 /* Compare the relative costs of "(X & (1 << BITNUM))" and "(X >> BITNUM) & 1",
 141    where X is an arbitrary register of mode MODE.  Return true if the former
 142    is preferred.  */
 143
 144 static bool
 145 prefer_and_bit_test (enum machine_mode mode, int bitnum)
 146 {
 147   bool speed_p;
 148
 149   if (and_test == 0)
 150     {
 151       /* Set up rtxes for the two variations.  Use NULL as a placeholder
 152          for the BITNUM-based constants.  */
 153       and_reg = gen_rtx_REG (mode, FIRST_PSEUDO_REGISTER);
 154       and_test = gen_rtx_AND (mode, and_reg, NULL);
 155       shift_test = gen_rtx_AND (mode, gen_rtx_ASHIFTRT (mode, and_reg, NULL),
 156                                 const1_rtx);
 157     }
 158   else
 159     {
 160       /* Change the mode of the previously-created rtxes.  */
 161       PUT_MODE (and_reg, mode);
 162       PUT_MODE (and_test, mode);
 163       PUT_MODE (shift_test, mode);
 164       PUT_MODE (XEXP (shift_test, 0), mode);
 165     }
 166
 167   /* Fill in the integers.  */
 168   XEXP (and_test, 1)
 169     = immed_double_int_const (double_int_setbit (double_int_zero, bitnum),
 170                                                  mode);
 171   XEXP (XEXP (shift_test, 0), 1) = GEN_INT (bitnum);
 172
 173   speed_p = optimize_insn_for_speed_p ();
 174   return (rtx_cost (and_test, IF_THEN_ELSE, 0, speed_p)
 175           <= rtx_cost (shift_test, IF_THEN_ELSE, 0, speed_p));
 176 }
 177
 178 /* Subroutine of do_jump, dealing with exploded comparisons of the type
 179    OP0 CODE OP1 .  IF_FALSE_LABEL and IF_TRUE_LABEL like in do_jump.
 180    PROB is probability of jump to if_true_label, or -1 if unknown.  */
 181
 182 void
 183 do_jump_1 (enum tree_code code, tree op0, tree op1,
 184            rtx if_false_label, rtx if_true_label, int prob)
 185 {
 186   enum machine_mode mode;
 187   rtx drop_through_label = 0;
 188
 189   switch (code)
 190     {
 191     case EQ_EXPR:
 192       {
 193         tree inner_type = TREE_TYPE (op0);
 194
 195         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 196                     != MODE_COMPLEX_FLOAT);
 197         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 198                     != MODE_COMPLEX_INT);
 199
 200         if (integer_zerop (op1))
 201           do_jump (op0, if_true_label, if_false_label, inv (prob));
 202         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 203                  && !can_compare_p (EQ, TYPE_MODE (inner_type), ccp_jump))
 204           do_jump_by_parts_equality (op0, op1, if_false_label, if_true_label,
 205                                      prob);
 206         else
 207           do_compare_and_jump (op0, op1, EQ, EQ, if_false_label, if_true_label,
 208                                prob);
 209         break;
 210       }
 211
 212     case NE_EXPR:
 213       {
 214         tree inner_type = TREE_TYPE (op0);
 215
 216         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 217                     != MODE_COMPLEX_FLOAT);
 218         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 219                     != MODE_COMPLEX_INT);
 220
 221         if (integer_zerop (op1))
 222           do_jump (op0, if_false_label, if_true_label, prob);
 223         else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
 224            && !can_compare_p (NE, TYPE_MODE (inner_type), ccp_jump))
 225           do_jump_by_parts_equality (op0, op1, if_true_label, if_false_label,
 226                                      inv (prob));
 227         else
 228           do_compare_and_jump (op0, op1, NE, NE, if_false_label, if_true_label,
 229                                prob);
 230         break;
 231       }
 232
 233     case LT_EXPR:
 234       mode = TYPE_MODE (TREE_TYPE (op0));
 235       if (GET_MODE_CLASS (mode) == MODE_INT
 236           && ! can_compare_p (LT, mode, ccp_jump))
 237         do_jump_by_parts_greater (op0, op1, 1, if_false_label, if_true_label,
 238                                   prob);
 239       else
 240         do_compare_and_jump (op0, op1, LT, LTU, if_false_label, if_true_label,
 241                              prob);
 242       break;
 243
 244     case LE_EXPR:
 245       mode = TYPE_MODE (TREE_TYPE (op0));
 246       if (GET_MODE_CLASS (mode) == MODE_INT
 247           && ! can_compare_p (LE, mode, ccp_jump))
 248         do_jump_by_parts_greater (op0, op1, 0, if_true_label, if_false_label,
 249                                   inv (prob));
 250       else
 251         do_compare_and_jump (op0, op1, LE, LEU, if_false_label, if_true_label,
 252                              prob);
 253       break;
 254
 255     case GT_EXPR:
 256       mode = TYPE_MODE (TREE_TYPE (op0));
 257       if (GET_MODE_CLASS (mode) == MODE_INT
 258           && ! can_compare_p (GT, mode, ccp_jump))
 259         do_jump_by_parts_greater (op0, op1, 0, if_false_label, if_true_label,
 260                                   prob);
 261       else
 262         do_compare_and_jump (op0, op1, GT, GTU, if_false_label, if_true_label,
 263                              prob);
 264       break;
 265
 266     case GE_EXPR:
 267       mode = TYPE_MODE (TREE_TYPE (op0));
 268       if (GET_MODE_CLASS (mode) == MODE_INT
 269           && ! can_compare_p (GE, mode, ccp_jump))
 270         do_jump_by_parts_greater (op0, op1, 1, if_true_label, if_false_label,
 271                                   inv (prob));
 272       else
 273         do_compare_and_jump (op0, op1, GE, GEU, if_false_label, if_true_label,
 274                              prob);
 275       break;
 276
 277     case ORDERED_EXPR:
 278       do_compare_and_jump (op0, op1, ORDERED, ORDERED,
 279                            if_false_label, if_true_label, prob);
 280       break;
 281
 282     case UNORDERED_EXPR:
 283       do_compare_and_jump (op0, op1, UNORDERED, UNORDERED,
 284                            if_false_label, if_true_label, prob);
 285       break;
 286
 287     case UNLT_EXPR:
 288       do_compare_and_jump (op0, op1, UNLT, UNLT, if_false_label, if_true_label,
 289                            prob);
 290       break;
 291
 292     case UNLE_EXPR:
 293       do_compare_and_jump (op0, op1, UNLE, UNLE, if_false_label, if_true_label,
 294                            prob);
 295       break;
 296
 297     case UNGT_EXPR:
 298       do_compare_and_jump (op0, op1, UNGT, UNGT, if_false_label, if_true_label,
 299                            prob);
 300       break;
 301
 302     case UNGE_EXPR:
 303       do_compare_and_jump (op0, op1, UNGE, UNGE, if_false_label, if_true_label,
 304                            prob);
 305       break;
 306
 307     case UNEQ_EXPR:
 308       do_compare_and_jump (op0, op1, UNEQ, UNEQ, if_false_label, if_true_label,
 309                            prob);
 310       break;
 311
 312     case LTGT_EXPR:
 313       do_compare_and_jump (op0, op1, LTGT, LTGT, if_false_label, if_true_label,
 314                            prob);
 315       break;
 316
 317     case TRUTH_ANDIF_EXPR:
 318       if (if_false_label == NULL_RTX)
 319         {
 320           drop_through_label = gen_label_rtx ();
 321           do_jump (op0, drop_through_label, NULL_RTX, prob);
 322           do_jump (op1, NULL_RTX, if_true_label, prob);
 323         }
 324       else
 325         {
 326           do_jump (op0, if_false_label, NULL_RTX, prob);
 327           do_jump (op1, if_false_label, if_true_label, prob);
 328         }
 329       break;
 330
 331     case TRUTH_ORIF_EXPR:
 332       if (if_true_label == NULL_RTX)
 333         {
 334           drop_through_label = gen_label_rtx ();
 335           do_jump (op0, NULL_RTX, drop_through_label, prob);
 336           do_jump (op1, if_false_label, NULL_RTX, prob);
 337         }
 338       else
 339         {
 340           do_jump (op0, NULL_RTX, if_true_label, prob);
 341           do_jump (op1, if_false_label, if_true_label, prob);
 342         }
 343       break;
 344
 345     default:
 346       gcc_unreachable ();
 347     }
 348
 349   if (drop_through_label)
 350     {
 351       do_pending_stack_adjust ();
 352       emit_label (drop_through_label);
 353     }
 354 }
 355
 356 /* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if
 357    the result is zero, or IF_TRUE_LABEL if the result is one.
 358    Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero,
 359    meaning fall through in that case.
 360
 361    do_jump always does any pending stack adjust except when it does not
 362    actually perform a jump.  An example where there is no jump
 363    is when EXP is `(foo (), 0)' and IF_FALSE_LABEL is null.
 364
 365    PROB is probability of jump to if_true_label, or -1 if unknown.  */
 366
 367 void
 368 do_jump (tree exp, rtx if_false_label, rtx if_true_label, int prob)
 369 {
 370   enum tree_code code = TREE_CODE (exp);
 371   rtx temp;
 372   int i;
 373   tree type;
 374   enum machine_mode mode;
 375   rtx drop_through_label = 0;
 376
 377   switch (code)
 378     {
 379     case ERROR_MARK:
 380       break;
 381
 382     case INTEGER_CST:
 383       temp = integer_zerop (exp) ? if_false_label : if_true_label;
 384       if (temp)
 385         emit_jump (temp);
 386       break;
 387
 388 #if 0
 389       /* This is not true with #pragma weak  */
 390     case ADDR_EXPR:
 391       /* The address of something can never be zero.  */
 392       if (if_true_label)
 393         emit_jump (if_true_label);
 394       break;
 395 #endif
 396
 397     case NOP_EXPR:
 398       if (TREE_CODE (TREE_OPERAND (exp, 0)) == COMPONENT_REF
 399           || TREE_CODE (TREE_OPERAND (exp, 0)) == BIT_FIELD_REF
 400           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF
 401           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_RANGE_REF)
 402         goto normal;
 403     case CONVERT_EXPR:
 404       /* If we are narrowing the operand, we have to do the compare in the
 405          narrower mode.  */
 406       if ((TYPE_PRECISION (TREE_TYPE (exp))
 407            < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
 408         goto normal;
 409     case NON_LVALUE_EXPR:
 410     case ABS_EXPR:
 411     case NEGATE_EXPR:
 412     case LROTATE_EXPR:
 413     case RROTATE_EXPR:
 414       /* These cannot change zero->nonzero or vice versa.  */
 415       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label, prob);
 416       break;
 417
 418     case TRUTH_NOT_EXPR:
 419       do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label,
 420                inv (prob));
 421       break;
 422
 423     case COND_EXPR:
 424       {
 425         rtx label1 = gen_label_rtx ();
 426         if (!if_true_label || !if_false_label)
 427           {
 428             drop_through_label = gen_label_rtx ();
 429             if (!if_true_label)
 430               if_true_label = drop_through_label;
 431             if (!if_false_label)
 432               if_false_label = drop_through_label;
 433           }
 434
 435         do_pending_stack_adjust ();
 436         do_jump (TREE_OPERAND (exp, 0), label1, NULL_RTX, -1);
 437         do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label, prob);
 438         emit_label (label1);
 439         do_jump (TREE_OPERAND (exp, 2), if_false_label, if_true_label, prob);
 440         break;
 441       }
 442
 443     case COMPOUND_EXPR:
 444       /* Lowered by gimplify.c.  */
 445       gcc_unreachable ();
 446
 447     case MINUS_EXPR:
 448       /* Nonzero iff operands of minus differ.  */
 449       code = NE_EXPR;
 450
 451       /* FALLTHRU */
 452     case EQ_EXPR:
 453     case NE_EXPR:
 454     case LT_EXPR:
 455     case LE_EXPR:
 456     case GT_EXPR:
 457     case GE_EXPR:
 458     case ORDERED_EXPR:
 459     case UNORDERED_EXPR:
 460     case UNLT_EXPR:
 461     case UNLE_EXPR:
 462     case UNGT_EXPR:
 463     case UNGE_EXPR:
 464     case UNEQ_EXPR:
 465     case LTGT_EXPR:
 466     case TRUTH_ANDIF_EXPR:
 467     case TRUTH_ORIF_EXPR:
 468     other_code:
 469       do_jump_1 (code, TREE_OPERAND (exp, 0), TREE_OPERAND (exp, 1),
 470                  if_false_label, if_true_label, prob);
 471       break;
 472
 473     case BIT_AND_EXPR:
 474       /* fold_single_bit_test() converts (X & (1 << C)) into (X >> C) & 1.
 475          See if the former is preferred for jump tests and restore it
 476          if so.  */
 477       if (integer_onep (TREE_OPERAND (exp, 1)))
 478         {
 479           tree exp0 = TREE_OPERAND (exp, 0);
 480           rtx set_label, clr_label;
 481           int setclr_prob = prob;
 482
 483           /* Strip narrowing integral type conversions.  */
 484           while (CONVERT_EXPR_P (exp0)
 485                  && TREE_OPERAND (exp0, 0) != error_mark_node
 486                  && TYPE_PRECISION (TREE_TYPE (exp0))
 487                     <= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp0, 0))))
 488             exp0 = TREE_OPERAND (exp0, 0);
 489
 490           /* "exp0 ^ 1" inverts the sense of the single bit test.  */
 491           if (TREE_CODE (exp0) == BIT_XOR_EXPR
 492               && integer_onep (TREE_OPERAND (exp0, 1)))
 493             {
 494               exp0 = TREE_OPERAND (exp0, 0);
 495               clr_label = if_true_label;
 496               set_label = if_false_label;
 497               setclr_prob = inv (prob);
 498             }
 499           else
 500             {
 501               clr_label = if_false_label;
 502               set_label = if_true_label;
 503             }
 504
 505           if (TREE_CODE (exp0) == RSHIFT_EXPR)
 506             {
 507               tree arg = TREE_OPERAND (exp0, 0);
 508               tree shift = TREE_OPERAND (exp0, 1);
 509               tree argtype = TREE_TYPE (arg);
 510               if (TREE_CODE (shift) == INTEGER_CST
 511                   && compare_tree_int (shift, 0) >= 0
 512                   && compare_tree_int (shift, HOST_BITS_PER_WIDE_INT) < 0
 513                   && prefer_and_bit_test (TYPE_MODE (argtype),
 514                                           TREE_INT_CST_LOW (shift)))
 515                 {
 516                   unsigned HOST_WIDE_INT mask
 517                     = (unsigned HOST_WIDE_INT) 1 << TREE_INT_CST_LOW (shift);
 518                   do_jump (build2 (BIT_AND_EXPR, argtype, arg,
 519                                    build_int_cstu (argtype, mask)),
 520                            clr_label, set_label, setclr_prob);
 521                   break;
 522                 }
 523             }
 524         }
 525
 526       /* If we are AND'ing with a small constant, do this comparison in the
 527          smallest type that fits.  If the machine doesn't have comparisons
 528          that small, it will be converted back to the wider comparison.
 529          This helps if we are testing the sign bit of a narrower object.
 530          combine can't do this for us because it can't know whether a
 531          ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */
 532
 533       if (! SLOW_BYTE_ACCESS
 534           && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
 535           && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT
 536           && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0
 537           && (mode = mode_for_size (i + 1, MODE_INT, 0)) != BLKmode
 538           && (type = lang_hooks.types.type_for_mode (mode, 1)) != 0
 539           && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 540           && have_insn_for (COMPARE, TYPE_MODE (type)))
 541         {
 542           do_jump (fold_convert (type, exp), if_false_label, if_true_label,
 543                    prob);
 544           break;
 545         }
 546
 547       if (TYPE_PRECISION (TREE_TYPE (exp)) > 1
 548           || TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST)
 549         goto normal;
 550
 551       /* Boolean comparisons can be compiled as TRUTH_AND_EXPR.  */
 552
 553     case TRUTH_AND_EXPR:
 554       /* High branch cost, expand as the bitwise AND of the conditions.
 555          Do the same if the RHS has side effects, because we're effectively
 556          turning a TRUTH_AND_EXPR into a TRUTH_ANDIF_EXPR.  */
 557       if (BRANCH_COST (optimize_insn_for_speed_p (),
 558                        false) >= 4
 559           || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))
 560         goto normal;
 561       code = TRUTH_ANDIF_EXPR;
 562       goto other_code;
 563
 564     case BIT_IOR_EXPR:
 565     case TRUTH_OR_EXPR:
 566       /* High branch cost, expand as the bitwise OR of the conditions.
 567          Do the same if the RHS has side effects, because we're effectively
 568          turning a TRUTH_OR_EXPR into a TRUTH_ORIF_EXPR.  */
 569       if (BRANCH_COST (optimize_insn_for_speed_p (), false) >= 4
 570           || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))
 571         goto normal;
 572       code = TRUTH_ORIF_EXPR;
 573       goto other_code;
 574
 575       /* Fall through and generate the normal code.  */
 576     default:
 577     normal:
 578       temp = expand_normal (exp);
 579       do_pending_stack_adjust ();
 580       /* The RTL optimizers prefer comparisons against pseudos.  */
 581       if (GET_CODE (temp) == SUBREG)
 582         {
 583           /* Compare promoted variables in their promoted mode.  */
 584           if (SUBREG_PROMOTED_VAR_P (temp)
 585               && REG_P (XEXP (temp, 0)))
 586             temp = XEXP (temp, 0);
 587           else
 588             temp = copy_to_reg (temp);
 589         }
 590       do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),
 591                                NE, TYPE_UNSIGNED (TREE_TYPE (exp)),
 592                                GET_MODE (temp), NULL_RTX,
 593                                if_false_label, if_true_label, prob);
 594     }
 595
 596   if (drop_through_label)
 597     {
 598       do_pending_stack_adjust ();
 599       emit_label (drop_through_label);
 600     }
 601 }
 602 \f
 603 /* Compare OP0 with OP1, word at a time, in mode MODE.
 604    UNSIGNEDP says to do unsigned comparison.
 605    Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */
 606
 607 static void
 608 do_jump_by_parts_greater_rtx (enum machine_mode mode, int unsignedp, rtx op0,
 609                               rtx op1, rtx if_false_label, rtx if_true_label,
 610                               int prob)
 611 {
 612   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 613   rtx drop_through_label = 0;
 614   bool drop_through_if_true = false, drop_through_if_false = false;
 615   enum rtx_code code = GT;
 616   int i;
 617
 618   if (! if_true_label || ! if_false_label)
 619     drop_through_label = gen_label_rtx ();
 620   if (! if_true_label)
 621     {
 622       if_true_label = drop_through_label;
 623       drop_through_if_true = true;
 624     }
 625   if (! if_false_label)
 626     {
 627       if_false_label = drop_through_label;
 628       drop_through_if_false = true;
 629     }
 630
 631   /* Deal with the special case 0 > x: only one comparison is necessary and
 632      we reverse it to avoid jumping to the drop-through label.  */
 633   if (op0 == const0_rtx && drop_through_if_true && !drop_through_if_false)
 634     {
 635       code = LE;
 636       if_true_label = if_false_label;
 637       if_false_label = drop_through_label;
 638       drop_through_if_true = false;
 639       drop_through_if_false = true;
 640     }
 641
 642   /* Compare a word at a time, high order first.  */
 643   for (i = 0; i < nwords; i++)
 644     {
 645       rtx op0_word, op1_word;
 646
 647       if (WORDS_BIG_ENDIAN)
 648         {
 649           op0_word = operand_subword_force (op0, i, mode);
 650           op1_word = operand_subword_force (op1, i, mode);
 651         }
 652       else
 653         {
 654           op0_word = operand_subword_force (op0, nwords - 1 - i, mode);
 655           op1_word = operand_subword_force (op1, nwords - 1 - i, mode);
 656         }
 657
 658       /* All but high-order word must be compared as unsigned.  */
 659       do_compare_rtx_and_jump (op0_word, op1_word, code, (unsignedp || i > 0),
 660                                word_mode, NULL_RTX, NULL_RTX, if_true_label,
 661                                prob);
 662
 663       /* Emit only one comparison for 0.  Do not emit the last cond jump.  */
 664       if (op0 == const0_rtx || i == nwords - 1)
 665         break;
 666
 667       /* Consider lower words only if these are equal.  */
 668       do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,
 669                                NULL_RTX, NULL_RTX, if_false_label, inv (prob));
 670     }
 671
 672   if (!drop_through_if_false)
 673     emit_jump (if_false_label);
 674   if (drop_through_label)
 675     emit_label (drop_through_label);
 676 }
 677
 678 /* Given a comparison expression EXP for values too wide to be compared
 679    with one insn, test the comparison and jump to the appropriate label.
 680    The code of EXP is ignored; we always test GT if SWAP is 0,
 681    and LT if SWAP is 1.  */
 682
 683 static void
 684 do_jump_by_parts_greater (tree treeop0, tree treeop1, int swap,
 685                           rtx if_false_label, rtx if_true_label, int prob)
 686 {
 687   rtx op0 = expand_normal (swap ? treeop1 : treeop0);
 688   rtx op1 = expand_normal (swap ? treeop0 : treeop1);
 689   enum machine_mode mode = TYPE_MODE (TREE_TYPE (treeop0));
 690   int unsignedp = TYPE_UNSIGNED (TREE_TYPE (treeop0));
 691
 692   do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label,
 693                                 if_true_label, prob);
 694 }
 695 \f
 696 /* Jump according to whether OP0 is 0.  We assume that OP0 has an integer
 697    mode, MODE, that is too wide for the available compare insns.  Either
 698    Either (but not both) of IF_TRUE_LABEL and IF_FALSE_LABEL may be NULL_RTX
 699    to indicate drop through.  */
 700
 701 static void
 702 do_jump_by_parts_zero_rtx (enum machine_mode mode, rtx op0,
 703                            rtx if_false_label, rtx if_true_label, int prob)
 704 {
 705   int nwords = GET_MODE_SIZE (mode) / UNITS_PER_WORD;
 706   rtx part;
 707   int i;
 708   rtx drop_through_label = 0;
 709
 710   /* The fastest way of doing this comparison on almost any machine is to
 711      "or" all the words and compare the result.  If all have to be loaded
 712      from memory and this is a very wide item, it's possible this may
 713      be slower, but that's highly unlikely.  */
 714
 715   part = gen_reg_rtx (word_mode);
 716   emit_move_insn (part, operand_subword_force (op0, 0, mode));
 717   for (i = 1; i < nwords && part != 0; i++)
 718     part = expand_binop (word_mode, ior_optab, part,
 719                          operand_subword_force (op0, i, mode),
 720                          part, 1, OPTAB_WIDEN);
 721
 722   if (part != 0)
 723     {
 724       do_compare_rtx_and_jump (part, const0_rtx, EQ, 1, word_mode,
 725                                NULL_RTX, if_false_label, if_true_label, prob);
 726       return;
 727     }
 728
 729   /* If we couldn't do the "or" simply, do this with a series of compares.  */
 730   if (! if_false_label)
 731     drop_through_label = if_false_label = gen_label_rtx ();
 732
 733   for (i = 0; i < nwords; i++)
 734     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 735                              const0_rtx, EQ, 1, word_mode, NULL_RTX,
 736                              if_false_label, NULL_RTX, prob);
 737
 738   if (if_true_label)
 739     emit_jump (if_true_label);
 740
 741   if (drop_through_label)
 742     emit_label (drop_through_label);
 743 }
 744
 745 /* Test for the equality of two RTX expressions OP0 and OP1 in mode MODE,
 746    where MODE is an integer mode too wide to be compared with one insn.
 747    Either (but not both) of IF_TRUE_LABEL and IF_FALSE_LABEL may be NULL_RTX
 748    to indicate drop through.  */
 749
 750 static void
 751 do_jump_by_parts_equality_rtx (enum machine_mode mode, rtx op0, rtx op1,
 752                                rtx if_false_label, rtx if_true_label, int prob)
 753 {
 754   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 755   rtx drop_through_label = 0;
 756   int i;
 757
 758   if (op1 == const0_rtx)
 759     {
 760       do_jump_by_parts_zero_rtx (mode, op0, if_false_label, if_true_label,
 761                                  prob);
 762       return;
 763     }
 764   else if (op0 == const0_rtx)
 765     {
 766       do_jump_by_parts_zero_rtx (mode, op1, if_false_label, if_true_label,
 767                                  prob);
 768       return;
 769     }
 770
 771   if (! if_false_label)
 772     drop_through_label = if_false_label = gen_label_rtx ();
 773
 774   for (i = 0; i < nwords; i++)
 775     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 776                              operand_subword_force (op1, i, mode),
 777                              EQ, 0, word_mode, NULL_RTX,
 778                              if_false_label, NULL_RTX, prob);
 779
 780   if (if_true_label)
 781     emit_jump (if_true_label);
 782   if (drop_through_label)
 783     emit_label (drop_through_label);
 784 }
 785
 786 /* Given an EQ_EXPR expression EXP for values too wide to be compared
 787    with one insn, test the comparison and jump to the appropriate label.  */
 788
 789 static void
 790 do_jump_by_parts_equality (tree treeop0, tree treeop1, rtx if_false_label,
 791                            rtx if_true_label, int prob)
 792 {
 793   rtx op0 = expand_normal (treeop0);
 794   rtx op1 = expand_normal (treeop1);
 795   enum machine_mode mode = TYPE_MODE (TREE_TYPE (treeop0));
 796   do_jump_by_parts_equality_rtx (mode, op0, op1, if_false_label,
 797                                  if_true_label, prob);
 798 }
 799 \f
 800 /* Split a comparison into two others, the second of which has the other
 801    "orderedness".  The first is always ORDERED or UNORDERED if MODE
 802    does not honor NaNs (which means that it can be skipped in that case;
 803    see do_compare_rtx_and_jump).
 804
 805    The two conditions are written in *CODE1 and *CODE2.  Return true if
 806    the conditions must be ANDed, false if they must be ORed.  */
 807
 808 bool
 809 split_comparison (enum rtx_code code, enum machine_mode mode,
 810                   enum rtx_code *code1, enum rtx_code *code2)
 811 {
 812   switch (code)
 813     {
 814     case LT:
 815       *code1 = ORDERED;
 816       *code2 = UNLT;
 817       return true;
 818     case LE:
 819       *code1 = ORDERED;
 820       *code2 = UNLE;
 821       return true;
 822     case GT:
 823       *code1 = ORDERED;
 824       *code2 = UNGT;
 825       return true;
 826     case GE:
 827       *code1 = ORDERED;
 828       *code2 = UNGE;
 829       return true;
 830     case EQ:
 831       *code1 = ORDERED;
 832       *code2 = UNEQ;
 833       return true;
 834     case NE:
 835       *code1 = UNORDERED;
 836       *code2 = LTGT;
 837       return false;
 838     case UNLT:
 839       *code1 = UNORDERED;
 840       *code2 = LT;
 841       return false;
 842     case UNLE:
 843       *code1 = UNORDERED;
 844       *code2 = LE;
 845       return false;
 846     case UNGT:
 847       *code1 = UNORDERED;
 848       *code2 = GT;
 849       return false;
 850     case UNGE:
 851       *code1 = UNORDERED;
 852       *code2 = GE;
 853       return false;
 854     case UNEQ:
 855       *code1 = UNORDERED;
 856       *code2 = EQ;
 857       return false;
 858     case LTGT:
 859       /* Do not turn a trapping comparison into a non-trapping one.  */
 860       if (HONOR_SNANS (mode))
 861         {
 862           *code1 = LT;
 863           *code2 = GT;
 864           return false;
 865         }
 866       else
 867         {
 868           *code1 = ORDERED;
 869           *code2 = NE;
 870           return true;
 871         }
 872     default:
 873       gcc_unreachable ();
 874     }
 875 }
 876
 877
 878 /* Like do_compare_and_jump but expects the values to compare as two rtx's.
 879    The decision as to signed or unsigned comparison must be made by the caller.
 880
 881    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 882    compared.  */
 883
 884 void
 885 do_compare_rtx_and_jump (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 886                          enum machine_mode mode, rtx size, rtx if_false_label,
 887                          rtx if_true_label, int prob)
 888 {
 889   rtx tem;
 890   rtx dummy_label = NULL_RTX;
 891   rtx last;
 892
 893   /* Reverse the comparison if that is safe and we want to jump if it is
 894      false.  Also convert to the reverse comparison if the target can
 895      implement it.  */
 896   if ((! if_true_label
 897        || ! can_compare_p (code, mode, ccp_jump))
 898       && (! FLOAT_MODE_P (mode)
 899           || code == ORDERED || code == UNORDERED
 900           || (! HONOR_NANS (mode) && (code == LTGT || code == UNEQ))
 901           || (! HONOR_SNANS (mode) && (code == EQ || code == NE))))
 902     {
 903       enum rtx_code rcode;
 904       if (FLOAT_MODE_P (mode))
 905         rcode = reverse_condition_maybe_unordered (code);
 906       else
 907         rcode = reverse_condition (code);
 908
 909       /* Canonicalize to UNORDERED for the libcall.  */
 910       if (can_compare_p (rcode, mode, ccp_jump)
 911           || (code == ORDERED && ! can_compare_p (ORDERED, mode, ccp_jump)))
 912         {
 913           tem = if_true_label;
 914           if_true_label = if_false_label;
 915           if_false_label = tem;
 916           code = rcode;
 917           prob = inv (prob);
 918         }
 919     }
 920
 921   /* If one operand is constant, make it the second one.  Only do this
 922      if the other operand is not constant as well.  */
 923
 924   if (swap_commutative_operands_p (op0, op1))
 925     {
 926       tem = op0;
 927       op0 = op1;
 928       op1 = tem;
 929       code = swap_condition (code);
 930     }
 931
 932   do_pending_stack_adjust ();
 933
 934   code = unsignedp ? unsigned_condition (code) : code;
 935   if (0 != (tem = simplify_relational_operation (code, mode, VOIDmode,
 936                                                  op0, op1)))
 937     {
 938       if (CONSTANT_P (tem))
 939         {
 940           rtx label = (tem == const0_rtx || tem == CONST0_RTX (mode))
 941                       ? if_false_label : if_true_label;
 942           if (label)
 943             emit_jump (label);
 944           return;
 945         }
 946
 947       code = GET_CODE (tem);
 948       mode = GET_MODE (tem);
 949       op0 = XEXP (tem, 0);
 950       op1 = XEXP (tem, 1);
 951       unsignedp = (code == GTU || code == LTU || code == GEU || code == LEU);
 952     }
 953
 954   if (! if_true_label)
 955     dummy_label = if_true_label = gen_label_rtx ();
 956
 957   if (GET_MODE_CLASS (mode) == MODE_INT
 958       && ! can_compare_p (code, mode, ccp_jump))
 959     {
 960       switch (code)
 961         {
 962         case LTU:
 963           do_jump_by_parts_greater_rtx (mode, 1, op1, op0,
 964                                         if_false_label, if_true_label, prob);
 965           break;
 966
 967         case LEU:
 968           do_jump_by_parts_greater_rtx (mode, 1, op0, op1,
 969                                         if_true_label, if_false_label,
 970                                         inv (prob));
 971           break;
 972
 973         case GTU:
 974           do_jump_by_parts_greater_rtx (mode, 1, op0, op1,
 975                                         if_false_label, if_true_label, prob);
 976           break;
 977
 978         case GEU:
 979           do_jump_by_parts_greater_rtx (mode, 1, op1, op0,
 980                                         if_true_label, if_false_label,
 981                                         inv (prob));
 982           break;
 983
 984         case LT:
 985           do_jump_by_parts_greater_rtx (mode, 0, op1, op0,
 986                                         if_false_label, if_true_label, prob);
 987           break;
 988
 989         case LE:
 990           do_jump_by_parts_greater_rtx (mode, 0, op0, op1,
 991                                         if_true_label, if_false_label,
 992                                         inv (prob));
 993           break;
 994
 995         case GT:
 996           do_jump_by_parts_greater_rtx (mode, 0, op0, op1,
 997                                         if_false_label, if_true_label, prob);
 998           break;
 999
1000         case GE:
1001           do_jump_by_parts_greater_rtx (mode, 0, op1, op0,
1002                                         if_true_label, if_false_label,
1003                                         inv (prob));
1004           break;
1005
1006         case EQ:
1007           do_jump_by_parts_equality_rtx (mode, op0, op1, if_false_label,
1008                                          if_true_label, prob);
1009           break;
1010
1011         case NE:
1012           do_jump_by_parts_equality_rtx (mode, op0, op1, if_true_label,
1013                                          if_false_label, inv (prob));
1014           break;
1015
1016         default:
1017           gcc_unreachable ();
1018         }
1019     }
1020   else
1021     {
1022       if (SCALAR_FLOAT_MODE_P (mode)
1023           && ! can_compare_p (code, mode, ccp_jump)
1024           && can_compare_p (swap_condition (code), mode, ccp_jump))
1025         {
1026           rtx tmp;
1027           code = swap_condition (code);
1028           tmp = op0;
1029           op0 = op1;
1030           op1 = tmp;
1031         }
1032
1033       else if (SCALAR_FLOAT_MODE_P (mode)
1034                && ! can_compare_p (code, mode, ccp_jump)
1035
1036                /* Never split ORDERED and UNORDERED.  These must be implemented.  */
1037                && (code != ORDERED && code != UNORDERED)
1038
1039                /* Split a floating-point comparison if we can jump on other
1040                   conditions...  */
1041                && (have_insn_for (COMPARE, mode)
1042
1043                    /* ... or if there is no libcall for it.  */
1044                    || code_to_optab[code] == NULL))
1045         {
1046           enum rtx_code first_code;
1047           bool and_them = split_comparison (code, mode, &first_code, &code);
1048
1049           /* If there are no NaNs, the first comparison should always fall
1050              through.  */
1051           if (!HONOR_NANS (mode))
1052             gcc_assert (first_code == (and_them ? ORDERED : UNORDERED));
1053
1054           else
1055             {
1056               if (and_them)
1057                 {
1058                   rtx dest_label;
1059                   /* If we only jump if true, just bypass the second jump.  */
1060                   if (! if_false_label)
1061                     {
1062                       if (! dummy_label)
1063                         dummy_label = gen_label_rtx ();
1064                       dest_label = dummy_label;
1065                     }
1066                   else
1067                     dest_label = if_false_label;
1068                   do_compare_rtx_and_jump (op0, op1, first_code, unsignedp, mode,
1069                                            size, dest_label, NULL_RTX, prob);
1070                 }
1071               else
1072                 do_compare_rtx_and_jump (op0, op1, first_code, unsignedp, mode,
1073                                          size, NULL_RTX, if_true_label, prob);
1074             }
1075         }
1076
1077       last = get_last_insn ();
1078       emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp,
1079                                if_true_label);
1080       if (prob != -1 && profile_status != PROFILE_ABSENT)
1081         {
1082           for (last = NEXT_INSN (last);
1083                last && NEXT_INSN (last);
1084                last = NEXT_INSN (last))
1085             if (JUMP_P (last))
1086               break;
1087           if (!last
1088               || !JUMP_P (last)
1089               || NEXT_INSN (last)
1090               || !any_condjump_p (last))
1091             {
1092               if (dump_file)
1093                 fprintf (dump_file, "Failed to add probability note\n");
1094             }
1095           else
1096             {
1097               gcc_assert (!find_reg_note (last, REG_BR_PROB, 0));
1098               add_reg_note (last, REG_BR_PROB, GEN_INT (prob));
1099             }
1100         }
1101     }
1102
1103   if (if_false_label)
1104     emit_jump (if_false_label);
1105   if (dummy_label)
1106     emit_label (dummy_label);
1107 }
1108
1109 /* Generate code for a comparison expression EXP (including code to compute
1110    the values to be compared) and a conditional jump to IF_FALSE_LABEL and/or
1111    IF_TRUE_LABEL.  One of the labels can be NULL_RTX, in which case the
1112    generated code will drop through.
1113    SIGNED_CODE should be the rtx operation for this comparison for
1114    signed data; UNSIGNED_CODE, likewise for use if data is unsigned.
1115
1116    We force a stack adjustment unless there are currently
1117    things pushed on the stack that aren't yet used.  */
1118
1119 static void
1120 do_compare_and_jump (tree treeop0, tree treeop1, enum rtx_code signed_code,
1121                      enum rtx_code unsigned_code, rtx if_false_label,
1122                      rtx if_true_label, int prob)
1123 {
1124   rtx op0, op1;
1125   tree type;
1126   enum machine_mode mode;
1127   int unsignedp;
1128   enum rtx_code code;
1129
1130   /* Don't crash if the comparison was erroneous.  */
1131   op0 = expand_normal (treeop0);
1132   if (TREE_CODE (treeop0) == ERROR_MARK)
1133     return;
1134
1135   op1 = expand_normal (treeop1);
1136   if (TREE_CODE (treeop1) == ERROR_MARK)
1137     return;
1138
1139   type = TREE_TYPE (treeop0);
1140   mode = TYPE_MODE (type);
1141   if (TREE_CODE (treeop0) == INTEGER_CST
1142       && (TREE_CODE (treeop1) != INTEGER_CST
1143           || (GET_MODE_BITSIZE (mode)
1144               > GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (treeop1))))))
1145     {
1146       /* op0 might have been replaced by promoted constant, in which
1147          case the type of second argument should be used.  */
1148       type = TREE_TYPE (treeop1);
1149       mode = TYPE_MODE (type);
1150     }
1151   unsignedp = TYPE_UNSIGNED (type);
1152   code = unsignedp ? unsigned_code : signed_code;
1153
1154 #ifdef HAVE_canonicalize_funcptr_for_compare
1155   /* If function pointers need to be "canonicalized" before they can
1156      be reliably compared, then canonicalize them.
1157      Only do this if *both* sides of the comparison are function pointers.
1158      If one side isn't, we want a noncanonicalized comparison.  See PR
1159      middle-end/17564.  */
1160   if (HAVE_canonicalize_funcptr_for_compare
1161       && TREE_CODE (TREE_TYPE (treeop0)) == POINTER_TYPE
1162       && TREE_CODE (TREE_TYPE (TREE_TYPE (treeop0)))
1163           == FUNCTION_TYPE
1164       && TREE_CODE (TREE_TYPE (treeop1)) == POINTER_TYPE
1165       && TREE_CODE (TREE_TYPE (TREE_TYPE (treeop1)))
1166           == FUNCTION_TYPE)
1167     {
1168       rtx new_op0 = gen_reg_rtx (mode);
1169       rtx new_op1 = gen_reg_rtx (mode);
1170
1171       emit_insn (gen_canonicalize_funcptr_for_compare (new_op0, op0));
1172       op0 = new_op0;
1173
1174       emit_insn (gen_canonicalize_funcptr_for_compare (new_op1, op1));
1175       op1 = new_op1;
1176     }
1177 #endif
1178
1179   do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode,
1180                            ((mode == BLKmode)
1181                             ? expr_size (treeop0) : NULL_RTX),
1182                            if_false_label, if_true_label, prob);
1183 }
1184
1185 #include "gt-dojump.h"