gcc/dojump.c

   1 /* Convert tree expression to rtl instructions, for GNU compiler.
   2    Copyright (C) 1988-2017 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "backend.h"
  24 #include "target.h"
  25 #include "rtl.h"
  26 #include "tree.h"
  27 #include "predict.h"
  28 #include "memmodel.h"
  29 #include "tm_p.h"
  30 #include "optabs.h"
  31 #include "emit-rtl.h"
  32 #include "fold-const.h"
  33 #include "stor-layout.h"
  34 /* Include expr.h after insn-config.h so we get HAVE_conditional_move.  */
  35 #include "dojump.h"
  36 #include "explow.h"
  37 #include "expr.h"
  38 #include "langhooks.h"
  39
  40 static bool prefer_and_bit_test (scalar_int_mode, int);
  41 static void do_jump_by_parts_greater (scalar_int_mode, tree, tree, int,
  42                                       rtx_code_label *, rtx_code_label *,
  43                                       profile_probability);
  44 static void do_jump_by_parts_equality (scalar_int_mode, tree, tree,
  45                                        rtx_code_label *, rtx_code_label *,
  46                                        profile_probability);
  47 static void do_compare_and_jump (tree, tree, enum rtx_code, enum rtx_code,
  48                                  rtx_code_label *, rtx_code_label *,
  49                                  profile_probability);
  50
  51 /* At the start of a function, record that we have no previously-pushed
  52    arguments waiting to be popped.  */
  53
  54 void
  55 init_pending_stack_adjust (void)
  56 {
  57   pending_stack_adjust = 0;
  58 }
  59
  60 /* Discard any pending stack adjustment.  This avoid relying on the
  61    RTL optimizers to remove useless adjustments when we know the
  62    stack pointer value is dead.  */
  63 void
  64 discard_pending_stack_adjust (void)
  65 {
  66   stack_pointer_delta -= pending_stack_adjust;
  67   pending_stack_adjust = 0;
  68 }
  69
  70 /* When exiting from function, if safe, clear out any pending stack adjust
  71    so the adjustment won't get done.
  72
  73    Note, if the current function calls alloca, then it must have a
  74    frame pointer regardless of the value of flag_omit_frame_pointer.  */
  75
  76 void
  77 clear_pending_stack_adjust (void)
  78 {
  79   if (optimize > 0
  80       && (! flag_omit_frame_pointer || cfun->calls_alloca)
  81       && EXIT_IGNORE_STACK)
  82     discard_pending_stack_adjust ();
  83 }
  84
  85 /* Pop any previously-pushed arguments that have not been popped yet.  */
  86
  87 void
  88 do_pending_stack_adjust (void)
  89 {
  90   if (inhibit_defer_pop == 0)
  91     {
  92       if (maybe_ne (pending_stack_adjust, 0))
  93         adjust_stack (gen_int_mode (pending_stack_adjust, Pmode));
  94       pending_stack_adjust = 0;
  95     }
  96 }
  97
  98 /* Remember pending_stack_adjust/stack_pointer_delta.
  99    To be used around code that may call do_pending_stack_adjust (),
 100    but the generated code could be discarded e.g. using delete_insns_since.  */
 101
 102 void
 103 save_pending_stack_adjust (saved_pending_stack_adjust *save)
 104 {
 105   save->x_pending_stack_adjust = pending_stack_adjust;
 106   save->x_stack_pointer_delta = stack_pointer_delta;
 107 }
 108
 109 /* Restore the saved pending_stack_adjust/stack_pointer_delta.  */
 110
 111 void
 112 restore_pending_stack_adjust (saved_pending_stack_adjust *save)
 113 {
 114   if (inhibit_defer_pop == 0)
 115     {
 116       pending_stack_adjust = save->x_pending_stack_adjust;
 117       stack_pointer_delta = save->x_stack_pointer_delta;
 118     }
 119 }
 120 \f
 121 /* Expand conditional expressions.  */
 122
 123 /* Generate code to evaluate EXP and jump to LABEL if the value is zero.  */
 124
 125 void
 126 jumpifnot (tree exp, rtx_code_label *label, profile_probability prob)
 127 {
 128   do_jump (exp, label, NULL, prob.invert ());
 129 }
 130
 131 void
 132 jumpifnot_1 (enum tree_code code, tree op0, tree op1, rtx_code_label *label,
 133              profile_probability prob)
 134 {
 135   do_jump_1 (code, op0, op1, label, NULL, prob.invert ());
 136 }
 137
 138 /* Generate code to evaluate EXP and jump to LABEL if the value is nonzero.  */
 139
 140 void
 141 jumpif (tree exp, rtx_code_label *label, profile_probability prob)
 142 {
 143   do_jump (exp, NULL, label, prob);
 144 }
 145
 146 void
 147 jumpif_1 (enum tree_code code, tree op0, tree op1,
 148           rtx_code_label *label, profile_probability prob)
 149 {
 150   do_jump_1 (code, op0, op1, NULL, label, prob);
 151 }
 152
 153 /* Used internally by prefer_and_bit_test.  */
 154
 155 static GTY(()) rtx and_reg;
 156 static GTY(()) rtx and_test;
 157 static GTY(()) rtx shift_test;
 158
 159 /* Compare the relative costs of "(X & (1 << BITNUM))" and "(X >> BITNUM) & 1",
 160    where X is an arbitrary register of mode MODE.  Return true if the former
 161    is preferred.  */
 162
 163 static bool
 164 prefer_and_bit_test (scalar_int_mode mode, int bitnum)
 165 {
 166   bool speed_p;
 167   wide_int mask = wi::set_bit_in_zero (bitnum, GET_MODE_PRECISION (mode));
 168
 169   if (and_test == 0)
 170     {
 171       /* Set up rtxes for the two variations.  Use NULL as a placeholder
 172          for the BITNUM-based constants.  */
 173       and_reg = gen_rtx_REG (mode, LAST_VIRTUAL_REGISTER + 1);
 174       and_test = gen_rtx_AND (mode, and_reg, NULL);
 175       shift_test = gen_rtx_AND (mode, gen_rtx_ASHIFTRT (mode, and_reg, NULL),
 176                                 const1_rtx);
 177     }
 178   else
 179     {
 180       /* Change the mode of the previously-created rtxes.  */
 181       PUT_MODE (and_reg, mode);
 182       PUT_MODE (and_test, mode);
 183       PUT_MODE (shift_test, mode);
 184       PUT_MODE (XEXP (shift_test, 0), mode);
 185     }
 186
 187   /* Fill in the integers.  */
 188   XEXP (and_test, 1) = immed_wide_int_const (mask, mode);
 189   XEXP (XEXP (shift_test, 0), 1) = GEN_INT (bitnum);
 190
 191   speed_p = optimize_insn_for_speed_p ();
 192   return (rtx_cost (and_test, mode, IF_THEN_ELSE, 0, speed_p)
 193           <= rtx_cost (shift_test, mode, IF_THEN_ELSE, 0, speed_p));
 194 }
 195
 196 /* Subroutine of do_jump, dealing with exploded comparisons of the type
 197    OP0 CODE OP1 .  IF_FALSE_LABEL and IF_TRUE_LABEL like in do_jump.
 198    PROB is probability of jump to if_true_label.  */
 199
 200 void
 201 do_jump_1 (enum tree_code code, tree op0, tree op1,
 202            rtx_code_label *if_false_label, rtx_code_label *if_true_label,
 203            profile_probability prob)
 204 {
 205   machine_mode mode;
 206   rtx_code_label *drop_through_label = 0;
 207   scalar_int_mode int_mode;
 208
 209   switch (code)
 210     {
 211     case EQ_EXPR:
 212       {
 213         tree inner_type = TREE_TYPE (op0);
 214
 215         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 216                     != MODE_COMPLEX_FLOAT);
 217         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 218                     != MODE_COMPLEX_INT);
 219
 220         if (integer_zerop (op1))
 221           do_jump (op0, if_true_label, if_false_label,
 222                    prob.invert ());
 223         else if (is_int_mode (TYPE_MODE (inner_type), &int_mode)
 224                  && !can_compare_p (EQ, int_mode, ccp_jump))
 225           do_jump_by_parts_equality (int_mode, op0, op1, if_false_label,
 226                                      if_true_label, prob);
 227         else
 228           do_compare_and_jump (op0, op1, EQ, EQ, if_false_label, if_true_label,
 229                                prob);
 230         break;
 231       }
 232
 233     case NE_EXPR:
 234       {
 235         tree inner_type = TREE_TYPE (op0);
 236
 237         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 238                     != MODE_COMPLEX_FLOAT);
 239         gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))
 240                     != MODE_COMPLEX_INT);
 241
 242         if (integer_zerop (op1))
 243           do_jump (op0, if_false_label, if_true_label, prob);
 244         else if (is_int_mode (TYPE_MODE (inner_type), &int_mode)
 245                  && !can_compare_p (NE, int_mode, ccp_jump))
 246           do_jump_by_parts_equality (int_mode, op0, op1, if_true_label,
 247                                      if_false_label, prob.invert ());
 248         else
 249           do_compare_and_jump (op0, op1, NE, NE, if_false_label, if_true_label,
 250                                prob);
 251         break;
 252       }
 253
 254     case LT_EXPR:
 255       mode = TYPE_MODE (TREE_TYPE (op0));
 256       if (is_int_mode (mode, &int_mode)
 257           && ! can_compare_p (LT, int_mode, ccp_jump))
 258         do_jump_by_parts_greater (int_mode, op0, op1, 1, if_false_label,
 259                                   if_true_label, prob);
 260       else
 261         do_compare_and_jump (op0, op1, LT, LTU, if_false_label, if_true_label,
 262                              prob);
 263       break;
 264
 265     case LE_EXPR:
 266       mode = TYPE_MODE (TREE_TYPE (op0));
 267       if (is_int_mode (mode, &int_mode)
 268           && ! can_compare_p (LE, int_mode, ccp_jump))
 269         do_jump_by_parts_greater (int_mode, op0, op1, 0, if_true_label,
 270                                   if_false_label, prob.invert ());
 271       else
 272         do_compare_and_jump (op0, op1, LE, LEU, if_false_label, if_true_label,
 273                              prob);
 274       break;
 275
 276     case GT_EXPR:
 277       mode = TYPE_MODE (TREE_TYPE (op0));
 278       if (is_int_mode (mode, &int_mode)
 279           && ! can_compare_p (GT, int_mode, ccp_jump))
 280         do_jump_by_parts_greater (int_mode, op0, op1, 0, if_false_label,
 281                                   if_true_label, prob);
 282       else
 283         do_compare_and_jump (op0, op1, GT, GTU, if_false_label, if_true_label,
 284                              prob);
 285       break;
 286
 287     case GE_EXPR:
 288       mode = TYPE_MODE (TREE_TYPE (op0));
 289       if (is_int_mode (mode, &int_mode)
 290           && ! can_compare_p (GE, int_mode, ccp_jump))
 291         do_jump_by_parts_greater (int_mode, op0, op1, 1, if_true_label,
 292                                   if_false_label, prob.invert ());
 293       else
 294         do_compare_and_jump (op0, op1, GE, GEU, if_false_label, if_true_label,
 295                              prob);
 296       break;
 297
 298     case ORDERED_EXPR:
 299       do_compare_and_jump (op0, op1, ORDERED, ORDERED,
 300                            if_false_label, if_true_label, prob);
 301       break;
 302
 303     case UNORDERED_EXPR:
 304       do_compare_and_jump (op0, op1, UNORDERED, UNORDERED,
 305                            if_false_label, if_true_label, prob);
 306       break;
 307
 308     case UNLT_EXPR:
 309       do_compare_and_jump (op0, op1, UNLT, UNLT, if_false_label, if_true_label,
 310                            prob);
 311       break;
 312
 313     case UNLE_EXPR:
 314       do_compare_and_jump (op0, op1, UNLE, UNLE, if_false_label, if_true_label,
 315                            prob);
 316       break;
 317
 318     case UNGT_EXPR:
 319       do_compare_and_jump (op0, op1, UNGT, UNGT, if_false_label, if_true_label,
 320                            prob);
 321       break;
 322
 323     case UNGE_EXPR:
 324       do_compare_and_jump (op0, op1, UNGE, UNGE, if_false_label, if_true_label,
 325                            prob);
 326       break;
 327
 328     case UNEQ_EXPR:
 329       do_compare_and_jump (op0, op1, UNEQ, UNEQ, if_false_label, if_true_label,
 330                            prob);
 331       break;
 332
 333     case LTGT_EXPR:
 334       do_compare_and_jump (op0, op1, LTGT, LTGT, if_false_label, if_true_label,
 335                            prob);
 336       break;
 337
 338     case TRUTH_ANDIF_EXPR:
 339       {
 340         /* Spread the probability that the expression is false evenly between
 341            the two conditions. So the first condition is false half the total
 342            probability of being false. The second condition is false the other
 343            half of the total probability of being false, so its jump has a false
 344            probability of half the total, relative to the probability we
 345            reached it (i.e. the first condition was true).  */
 346         profile_probability op0_prob = profile_probability::uninitialized ();
 347         profile_probability op1_prob = profile_probability::uninitialized ();
 348         if (prob.initialized_p ())
 349           {
 350             profile_probability false_prob = prob.invert ();
 351             profile_probability op0_false_prob = false_prob.apply_scale (1, 2);
 352             profile_probability op1_false_prob = false_prob.apply_scale (1, 2)
 353                                 / op0_false_prob.invert ();
 354             /* Get the probability that each jump below is true.  */
 355             op0_prob = op0_false_prob.invert ();
 356             op1_prob = op1_false_prob.invert ();
 357           }
 358         if (if_false_label == NULL)
 359           {
 360             drop_through_label = gen_label_rtx ();
 361             do_jump (op0, drop_through_label, NULL, op0_prob);
 362             do_jump (op1, NULL, if_true_label, op1_prob);
 363           }
 364         else
 365           {
 366             do_jump (op0, if_false_label, NULL, op0_prob);
 367             do_jump (op1, if_false_label, if_true_label, op1_prob);
 368           }
 369         break;
 370       }
 371
 372     case TRUTH_ORIF_EXPR:
 373       {
 374         /* Spread the probability evenly between the two conditions. So
 375            the first condition has half the total probability of being true.
 376            The second condition has the other half of the total probability,
 377            so its jump has a probability of half the total, relative to
 378            the probability we reached it (i.e. the first condition was false).  */
 379         profile_probability op0_prob = profile_probability::uninitialized ();
 380         profile_probability op1_prob = profile_probability::uninitialized ();
 381         if (prob.initialized_p ())
 382           {
 383             op0_prob = prob.apply_scale (1, 2);
 384             op1_prob = prob.apply_scale (1, 2) / op0_prob.invert ();
 385           }
 386         if (if_true_label == NULL)
 387           {
 388             drop_through_label = gen_label_rtx ();
 389             do_jump (op0, NULL, drop_through_label, op0_prob);
 390             do_jump (op1, if_false_label, NULL, op1_prob);
 391           }
 392         else
 393           {
 394             do_jump (op0, NULL, if_true_label, op0_prob);
 395             do_jump (op1, if_false_label, if_true_label, op1_prob);
 396           }
 397         break;
 398       }
 399
 400     default:
 401       gcc_unreachable ();
 402     }
 403
 404   if (drop_through_label)
 405     {
 406       do_pending_stack_adjust ();
 407       emit_label (drop_through_label);
 408     }
 409 }
 410
 411 /* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if
 412    the result is zero, or IF_TRUE_LABEL if the result is one.
 413    Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero,
 414    meaning fall through in that case.
 415
 416    do_jump always does any pending stack adjust except when it does not
 417    actually perform a jump.  An example where there is no jump
 418    is when EXP is `(foo (), 0)' and IF_FALSE_LABEL is null.
 419
 420    PROB is probability of jump to if_true_label.  */
 421
 422 void
 423 do_jump (tree exp, rtx_code_label *if_false_label,
 424          rtx_code_label *if_true_label, profile_probability prob)
 425 {
 426   enum tree_code code = TREE_CODE (exp);
 427   rtx temp;
 428   int i;
 429   tree type;
 430   scalar_int_mode mode;
 431   rtx_code_label *drop_through_label = NULL;
 432
 433   switch (code)
 434     {
 435     case ERROR_MARK:
 436       break;
 437
 438     case INTEGER_CST:
 439       {
 440         rtx_code_label *lab = integer_zerop (exp) ? if_false_label
 441                                                   : if_true_label;
 442         if (lab)
 443           emit_jump (lab);
 444         break;
 445       }
 446
 447 #if 0
 448       /* This is not true with #pragma weak  */
 449     case ADDR_EXPR:
 450       /* The address of something can never be zero.  */
 451       if (if_true_label)
 452         emit_jump (if_true_label);
 453       break;
 454 #endif
 455
 456     case NOP_EXPR:
 457       if (TREE_CODE (TREE_OPERAND (exp, 0)) == COMPONENT_REF
 458           || TREE_CODE (TREE_OPERAND (exp, 0)) == BIT_FIELD_REF
 459           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF
 460           || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_RANGE_REF)
 461         goto normal;
 462       /* FALLTHRU */
 463     case CONVERT_EXPR:
 464       /* If we are narrowing the operand, we have to do the compare in the
 465          narrower mode.  */
 466       if ((TYPE_PRECISION (TREE_TYPE (exp))
 467            < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
 468         goto normal;
 469       /* FALLTHRU */
 470     case NON_LVALUE_EXPR:
 471     case ABS_EXPR:
 472     case NEGATE_EXPR:
 473     case LROTATE_EXPR:
 474     case RROTATE_EXPR:
 475       /* These cannot change zero->nonzero or vice versa.  */
 476       do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label, prob);
 477       break;
 478
 479     case TRUTH_NOT_EXPR:
 480       do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label,
 481                prob.invert ());
 482       break;
 483
 484     case COND_EXPR:
 485       {
 486         rtx_code_label *label1 = gen_label_rtx ();
 487         if (!if_true_label || !if_false_label)
 488           {
 489             drop_through_label = gen_label_rtx ();
 490             if (!if_true_label)
 491               if_true_label = drop_through_label;
 492             if (!if_false_label)
 493               if_false_label = drop_through_label;
 494           }
 495
 496         do_pending_stack_adjust ();
 497         do_jump (TREE_OPERAND (exp, 0), label1, NULL,
 498                  profile_probability::uninitialized ());
 499         do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label, prob);
 500         emit_label (label1);
 501         do_jump (TREE_OPERAND (exp, 2), if_false_label, if_true_label, prob);
 502         break;
 503       }
 504
 505     case COMPOUND_EXPR:
 506       /* Lowered by gimplify.c.  */
 507       gcc_unreachable ();
 508
 509     case MINUS_EXPR:
 510       /* Nonzero iff operands of minus differ.  */
 511       code = NE_EXPR;
 512
 513       /* FALLTHRU */
 514     case EQ_EXPR:
 515     case NE_EXPR:
 516     case LT_EXPR:
 517     case LE_EXPR:
 518     case GT_EXPR:
 519     case GE_EXPR:
 520     case ORDERED_EXPR:
 521     case UNORDERED_EXPR:
 522     case UNLT_EXPR:
 523     case UNLE_EXPR:
 524     case UNGT_EXPR:
 525     case UNGE_EXPR:
 526     case UNEQ_EXPR:
 527     case LTGT_EXPR:
 528     case TRUTH_ANDIF_EXPR:
 529     case TRUTH_ORIF_EXPR:
 530     other_code:
 531       do_jump_1 (code, TREE_OPERAND (exp, 0), TREE_OPERAND (exp, 1),
 532                  if_false_label, if_true_label, prob);
 533       break;
 534
 535     case BIT_AND_EXPR:
 536       /* fold_single_bit_test() converts (X & (1 << C)) into (X >> C) & 1.
 537          See if the former is preferred for jump tests and restore it
 538          if so.  */
 539       if (integer_onep (TREE_OPERAND (exp, 1)))
 540         {
 541           tree exp0 = TREE_OPERAND (exp, 0);
 542           rtx_code_label *set_label, *clr_label;
 543           profile_probability setclr_prob = prob;
 544
 545           /* Strip narrowing integral type conversions.  */
 546           while (CONVERT_EXPR_P (exp0)
 547                  && TREE_OPERAND (exp0, 0) != error_mark_node
 548                  && TYPE_PRECISION (TREE_TYPE (exp0))
 549                     <= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp0, 0))))
 550             exp0 = TREE_OPERAND (exp0, 0);
 551
 552           /* "exp0 ^ 1" inverts the sense of the single bit test.  */
 553           if (TREE_CODE (exp0) == BIT_XOR_EXPR
 554               && integer_onep (TREE_OPERAND (exp0, 1)))
 555             {
 556               exp0 = TREE_OPERAND (exp0, 0);
 557               clr_label = if_true_label;
 558               set_label = if_false_label;
 559               setclr_prob = prob.invert ();
 560             }
 561           else
 562             {
 563               clr_label = if_false_label;
 564               set_label = if_true_label;
 565             }
 566
 567           if (TREE_CODE (exp0) == RSHIFT_EXPR)
 568             {
 569               tree arg = TREE_OPERAND (exp0, 0);
 570               tree shift = TREE_OPERAND (exp0, 1);
 571               tree argtype = TREE_TYPE (arg);
 572               if (TREE_CODE (shift) == INTEGER_CST
 573                   && compare_tree_int (shift, 0) >= 0
 574                   && compare_tree_int (shift, HOST_BITS_PER_WIDE_INT) < 0
 575                   && prefer_and_bit_test (SCALAR_INT_TYPE_MODE (argtype),
 576                                           TREE_INT_CST_LOW (shift)))
 577                 {
 578                   unsigned HOST_WIDE_INT mask
 579                     = HOST_WIDE_INT_1U << TREE_INT_CST_LOW (shift);
 580                   do_jump (build2 (BIT_AND_EXPR, argtype, arg,
 581                                    build_int_cstu (argtype, mask)),
 582                            clr_label, set_label, setclr_prob);
 583                   break;
 584                 }
 585             }
 586         }
 587
 588       /* If we are AND'ing with a small constant, do this comparison in the
 589          smallest type that fits.  If the machine doesn't have comparisons
 590          that small, it will be converted back to the wider comparison.
 591          This helps if we are testing the sign bit of a narrower object.
 592          combine can't do this for us because it can't know whether a
 593          ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */
 594
 595       if (! SLOW_BYTE_ACCESS
 596           && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
 597           && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT
 598           && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0
 599           && int_mode_for_size (i + 1, 0).exists (&mode)
 600           && (type = lang_hooks.types.type_for_mode (mode, 1)) != 0
 601           && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
 602           && have_insn_for (COMPARE, TYPE_MODE (type)))
 603         {
 604           do_jump (fold_convert (type, exp), if_false_label, if_true_label,
 605                    prob);
 606           break;
 607         }
 608
 609       if (TYPE_PRECISION (TREE_TYPE (exp)) > 1
 610           || TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST)
 611         goto normal;
 612
 613       /* Boolean comparisons can be compiled as TRUTH_AND_EXPR.  */
 614       /* FALLTHRU */
 615
 616     case TRUTH_AND_EXPR:
 617       /* High branch cost, expand as the bitwise AND of the conditions.
 618          Do the same if the RHS has side effects, because we're effectively
 619          turning a TRUTH_AND_EXPR into a TRUTH_ANDIF_EXPR.  */
 620       if (BRANCH_COST (optimize_insn_for_speed_p (),
 621                        false) >= 4
 622           || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))
 623         goto normal;
 624       code = TRUTH_ANDIF_EXPR;
 625       goto other_code;
 626
 627     case BIT_IOR_EXPR:
 628     case TRUTH_OR_EXPR:
 629       /* High branch cost, expand as the bitwise OR of the conditions.
 630          Do the same if the RHS has side effects, because we're effectively
 631          turning a TRUTH_OR_EXPR into a TRUTH_ORIF_EXPR.  */
 632       if (BRANCH_COST (optimize_insn_for_speed_p (), false) >= 4
 633           || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))
 634         goto normal;
 635       code = TRUTH_ORIF_EXPR;
 636       goto other_code;
 637
 638       /* Fall through and generate the normal code.  */
 639     default:
 640     normal:
 641       temp = expand_normal (exp);
 642       do_pending_stack_adjust ();
 643       /* The RTL optimizers prefer comparisons against pseudos.  */
 644       if (GET_CODE (temp) == SUBREG)
 645         {
 646           /* Compare promoted variables in their promoted mode.  */
 647           if (SUBREG_PROMOTED_VAR_P (temp)
 648               && REG_P (XEXP (temp, 0)))
 649             temp = XEXP (temp, 0);
 650           else
 651             temp = copy_to_reg (temp);
 652         }
 653       do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),
 654                                NE, TYPE_UNSIGNED (TREE_TYPE (exp)),
 655                                GET_MODE (temp), NULL_RTX,
 656                                if_false_label, if_true_label, prob);
 657     }
 658
 659   if (drop_through_label)
 660     {
 661       do_pending_stack_adjust ();
 662       emit_label (drop_through_label);
 663     }
 664 }
 665 \f
 666 /* Compare OP0 with OP1, word at a time, in mode MODE.
 667    UNSIGNEDP says to do unsigned comparison.
 668    Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */
 669
 670 static void
 671 do_jump_by_parts_greater_rtx (scalar_int_mode mode, int unsignedp, rtx op0,
 672                               rtx op1, rtx_code_label *if_false_label,
 673                               rtx_code_label *if_true_label,
 674                               profile_probability prob)
 675 {
 676   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 677   rtx_code_label *drop_through_label = 0;
 678   bool drop_through_if_true = false, drop_through_if_false = false;
 679   enum rtx_code code = GT;
 680   int i;
 681
 682   if (! if_true_label || ! if_false_label)
 683     drop_through_label = gen_label_rtx ();
 684   if (! if_true_label)
 685     {
 686       if_true_label = drop_through_label;
 687       drop_through_if_true = true;
 688     }
 689   if (! if_false_label)
 690     {
 691       if_false_label = drop_through_label;
 692       drop_through_if_false = true;
 693     }
 694
 695   /* Deal with the special case 0 > x: only one comparison is necessary and
 696      we reverse it to avoid jumping to the drop-through label.  */
 697   if (op0 == const0_rtx && drop_through_if_true && !drop_through_if_false)
 698     {
 699       code = LE;
 700       if_true_label = if_false_label;
 701       if_false_label = drop_through_label;
 702       drop_through_if_true = false;
 703       drop_through_if_false = true;
 704       prob = prob.invert ();
 705     }
 706
 707   /* Compare a word at a time, high order first.  */
 708   for (i = 0; i < nwords; i++)
 709     {
 710       rtx op0_word, op1_word;
 711
 712       if (WORDS_BIG_ENDIAN)
 713         {
 714           op0_word = operand_subword_force (op0, i, mode);
 715           op1_word = operand_subword_force (op1, i, mode);
 716         }
 717       else
 718         {
 719           op0_word = operand_subword_force (op0, nwords - 1 - i, mode);
 720           op1_word = operand_subword_force (op1, nwords - 1 - i, mode);
 721         }
 722
 723       /* All but high-order word must be compared as unsigned.  */
 724       do_compare_rtx_and_jump (op0_word, op1_word, code, (unsignedp || i > 0),
 725                                word_mode, NULL_RTX, NULL, if_true_label,
 726                                prob);
 727
 728       /* Emit only one comparison for 0.  Do not emit the last cond jump.  */
 729       if (op0 == const0_rtx || i == nwords - 1)
 730         break;
 731
 732       /* Consider lower words only if these are equal.  */
 733       do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,
 734                                NULL_RTX, NULL, if_false_label,
 735                                prob.invert ());
 736     }
 737
 738   if (!drop_through_if_false)
 739     emit_jump (if_false_label);
 740   if (drop_through_label)
 741     emit_label (drop_through_label);
 742 }
 743
 744 /* Given a comparison expression EXP for values too wide to be compared
 745    with one insn, test the comparison and jump to the appropriate label.
 746    The code of EXP is ignored; we always test GT if SWAP is 0,
 747    and LT if SWAP is 1.  MODE is the mode of the two operands.  */
 748
 749 static void
 750 do_jump_by_parts_greater (scalar_int_mode mode, tree treeop0, tree treeop1,
 751                           int swap, rtx_code_label *if_false_label,
 752                           rtx_code_label *if_true_label,
 753                           profile_probability prob)
 754 {
 755   rtx op0 = expand_normal (swap ? treeop1 : treeop0);
 756   rtx op1 = expand_normal (swap ? treeop0 : treeop1);
 757   int unsignedp = TYPE_UNSIGNED (TREE_TYPE (treeop0));
 758
 759   do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label,
 760                                 if_true_label, prob);
 761 }
 762 \f
 763 /* Jump according to whether OP0 is 0.  We assume that OP0 has an integer
 764    mode, MODE, that is too wide for the available compare insns.  Either
 765    Either (but not both) of IF_TRUE_LABEL and IF_FALSE_LABEL may be NULL
 766    to indicate drop through.  */
 767
 768 static void
 769 do_jump_by_parts_zero_rtx (scalar_int_mode mode, rtx op0,
 770                            rtx_code_label *if_false_label,
 771                            rtx_code_label *if_true_label,
 772                            profile_probability prob)
 773 {
 774   int nwords = GET_MODE_SIZE (mode) / UNITS_PER_WORD;
 775   rtx part;
 776   int i;
 777   rtx_code_label *drop_through_label = NULL;
 778
 779   /* The fastest way of doing this comparison on almost any machine is to
 780      "or" all the words and compare the result.  If all have to be loaded
 781      from memory and this is a very wide item, it's possible this may
 782      be slower, but that's highly unlikely.  */
 783
 784   part = gen_reg_rtx (word_mode);
 785   emit_move_insn (part, operand_subword_force (op0, 0, mode));
 786   for (i = 1; i < nwords && part != 0; i++)
 787     part = expand_binop (word_mode, ior_optab, part,
 788                          operand_subword_force (op0, i, mode),
 789                          part, 1, OPTAB_WIDEN);
 790
 791   if (part != 0)
 792     {
 793       do_compare_rtx_and_jump (part, const0_rtx, EQ, 1, word_mode,
 794                                NULL_RTX, if_false_label, if_true_label, prob);
 795       return;
 796     }
 797
 798   /* If we couldn't do the "or" simply, do this with a series of compares.  */
 799   if (! if_false_label)
 800     if_false_label = drop_through_label = gen_label_rtx ();
 801
 802   for (i = 0; i < nwords; i++)
 803     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 804                              const0_rtx, EQ, 1, word_mode, NULL_RTX,
 805                              if_false_label, NULL, prob);
 806
 807   if (if_true_label)
 808     emit_jump (if_true_label);
 809
 810   if (drop_through_label)
 811     emit_label (drop_through_label);
 812 }
 813
 814 /* Test for the equality of two RTX expressions OP0 and OP1 in mode MODE,
 815    where MODE is an integer mode too wide to be compared with one insn.
 816    Either (but not both) of IF_TRUE_LABEL and IF_FALSE_LABEL may be NULL_RTX
 817    to indicate drop through.  */
 818
 819 static void
 820 do_jump_by_parts_equality_rtx (scalar_int_mode mode, rtx op0, rtx op1,
 821                                rtx_code_label *if_false_label,
 822                                rtx_code_label *if_true_label,
 823                                profile_probability prob)
 824 {
 825   int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
 826   rtx_code_label *drop_through_label = NULL;
 827   int i;
 828
 829   if (op1 == const0_rtx)
 830     {
 831       do_jump_by_parts_zero_rtx (mode, op0, if_false_label, if_true_label,
 832                                  prob);
 833       return;
 834     }
 835   else if (op0 == const0_rtx)
 836     {
 837       do_jump_by_parts_zero_rtx (mode, op1, if_false_label, if_true_label,
 838                                  prob);
 839       return;
 840     }
 841
 842   if (! if_false_label)
 843     drop_through_label = if_false_label = gen_label_rtx ();
 844
 845   for (i = 0; i < nwords; i++)
 846     do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
 847                              operand_subword_force (op1, i, mode),
 848                              EQ, 0, word_mode, NULL_RTX,
 849                              if_false_label, NULL, prob);
 850
 851   if (if_true_label)
 852     emit_jump (if_true_label);
 853   if (drop_through_label)
 854     emit_label (drop_through_label);
 855 }
 856
 857 /* Given an EQ_EXPR expression EXP for values too wide to be compared
 858    with one insn, test the comparison and jump to the appropriate label.
 859    MODE is the mode of the two operands.  */
 860
 861 static void
 862 do_jump_by_parts_equality (scalar_int_mode mode, tree treeop0, tree treeop1,
 863                            rtx_code_label *if_false_label,
 864                            rtx_code_label *if_true_label,
 865                            profile_probability prob)
 866 {
 867   rtx op0 = expand_normal (treeop0);
 868   rtx op1 = expand_normal (treeop1);
 869   do_jump_by_parts_equality_rtx (mode, op0, op1, if_false_label,
 870                                  if_true_label, prob);
 871 }
 872 \f
 873 /* Split a comparison into two others, the second of which has the other
 874    "orderedness".  The first is always ORDERED or UNORDERED if MODE
 875    does not honor NaNs (which means that it can be skipped in that case;
 876    see do_compare_rtx_and_jump).
 877
 878    The two conditions are written in *CODE1 and *CODE2.  Return true if
 879    the conditions must be ANDed, false if they must be ORed.  */
 880
 881 bool
 882 split_comparison (enum rtx_code code, machine_mode mode,
 883                   enum rtx_code *code1, enum rtx_code *code2)
 884 {
 885   switch (code)
 886     {
 887     case LT:
 888       *code1 = ORDERED;
 889       *code2 = UNLT;
 890       return true;
 891     case LE:
 892       *code1 = ORDERED;
 893       *code2 = UNLE;
 894       return true;
 895     case GT:
 896       *code1 = ORDERED;
 897       *code2 = UNGT;
 898       return true;
 899     case GE:
 900       *code1 = ORDERED;
 901       *code2 = UNGE;
 902       return true;
 903     case EQ:
 904       *code1 = ORDERED;
 905       *code2 = UNEQ;
 906       return true;
 907     case NE:
 908       *code1 = UNORDERED;
 909       *code2 = LTGT;
 910       return false;
 911     case UNLT:
 912       *code1 = UNORDERED;
 913       *code2 = LT;
 914       return false;
 915     case UNLE:
 916       *code1 = UNORDERED;
 917       *code2 = LE;
 918       return false;
 919     case UNGT:
 920       *code1 = UNORDERED;
 921       *code2 = GT;
 922       return false;
 923     case UNGE:
 924       *code1 = UNORDERED;
 925       *code2 = GE;
 926       return false;
 927     case UNEQ:
 928       *code1 = UNORDERED;
 929       *code2 = EQ;
 930       return false;
 931     case LTGT:
 932       /* Do not turn a trapping comparison into a non-trapping one.  */
 933       if (HONOR_SNANS (mode))
 934         {
 935           *code1 = LT;
 936           *code2 = GT;
 937           return false;
 938         }
 939       else
 940         {
 941           *code1 = ORDERED;
 942           *code2 = NE;
 943           return true;
 944         }
 945     default:
 946       gcc_unreachable ();
 947     }
 948 }
 949
 950
 951 /* Like do_compare_and_jump but expects the values to compare as two rtx's.
 952    The decision as to signed or unsigned comparison must be made by the caller.
 953
 954    If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
 955    compared.  */
 956
 957 void
 958 do_compare_rtx_and_jump (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 959                          machine_mode mode, rtx size,
 960                          rtx_code_label *if_false_label,
 961                          rtx_code_label *if_true_label,
 962                          profile_probability prob)
 963 {
 964   rtx tem;
 965   rtx_code_label *dummy_label = NULL;
 966
 967   /* Reverse the comparison if that is safe and we want to jump if it is
 968      false.  Also convert to the reverse comparison if the target can
 969      implement it.  */
 970   if ((! if_true_label
 971        || ! can_compare_p (code, mode, ccp_jump))
 972       && (! FLOAT_MODE_P (mode)
 973           || code == ORDERED || code == UNORDERED
 974           || (! HONOR_NANS (mode) && (code == LTGT || code == UNEQ))
 975           || (! HONOR_SNANS (mode) && (code == EQ || code == NE))))
 976     {
 977       enum rtx_code rcode;
 978       if (FLOAT_MODE_P (mode))
 979         rcode = reverse_condition_maybe_unordered (code);
 980       else
 981         rcode = reverse_condition (code);
 982
 983       /* Canonicalize to UNORDERED for the libcall.  */
 984       if (can_compare_p (rcode, mode, ccp_jump)
 985           || (code == ORDERED && ! can_compare_p (ORDERED, mode, ccp_jump)))
 986         {
 987           std::swap (if_true_label, if_false_label);
 988           code = rcode;
 989           prob = prob.invert ();
 990         }
 991     }
 992
 993   /* If one operand is constant, make it the second one.  Only do this
 994      if the other operand is not constant as well.  */
 995
 996   if (swap_commutative_operands_p (op0, op1))
 997     {
 998       std::swap (op0, op1);
 999       code = swap_condition (code);
1000     }
1001
1002   do_pending_stack_adjust ();
1003
1004   code = unsignedp ? unsigned_condition (code) : code;
1005   if ((tem = simplify_relational_operation (code, mode, VOIDmode,
1006                                             op0, op1)) != 0)
1007     {
1008       if (CONSTANT_P (tem))
1009         {
1010           rtx_code_label *label = (tem == const0_rtx
1011                                    || tem == CONST0_RTX (mode))
1012                                         ? if_false_label : if_true_label;
1013           if (label)
1014             emit_jump (label);
1015           return;
1016         }
1017
1018       code = GET_CODE (tem);
1019       mode = GET_MODE (tem);
1020       op0 = XEXP (tem, 0);
1021       op1 = XEXP (tem, 1);
1022       unsignedp = (code == GTU || code == LTU || code == GEU || code == LEU);
1023     }
1024
1025   if (! if_true_label)
1026     dummy_label = if_true_label = gen_label_rtx ();
1027
1028   scalar_int_mode int_mode;
1029   if (is_int_mode (mode, &int_mode)
1030       && ! can_compare_p (code, int_mode, ccp_jump))
1031     {
1032       switch (code)
1033         {
1034         case LTU:
1035           do_jump_by_parts_greater_rtx (int_mode, 1, op1, op0,
1036                                         if_false_label, if_true_label, prob);
1037           break;
1038
1039         case LEU:
1040           do_jump_by_parts_greater_rtx (int_mode, 1, op0, op1,
1041                                         if_true_label, if_false_label,
1042                                         prob.invert ());
1043           break;
1044
1045         case GTU:
1046           do_jump_by_parts_greater_rtx (int_mode, 1, op0, op1,
1047                                         if_false_label, if_true_label, prob);
1048           break;
1049
1050         case GEU:
1051           do_jump_by_parts_greater_rtx (int_mode, 1, op1, op0,
1052                                         if_true_label, if_false_label,
1053                                         prob.invert ());
1054           break;
1055
1056         case LT:
1057           do_jump_by_parts_greater_rtx (int_mode, 0, op1, op0,
1058                                         if_false_label, if_true_label, prob);
1059           break;
1060
1061         case LE:
1062           do_jump_by_parts_greater_rtx (int_mode, 0, op0, op1,
1063                                         if_true_label, if_false_label,
1064                                         prob.invert ());
1065           break;
1066
1067         case GT:
1068           do_jump_by_parts_greater_rtx (int_mode, 0, op0, op1,
1069                                         if_false_label, if_true_label, prob);
1070           break;
1071
1072         case GE:
1073           do_jump_by_parts_greater_rtx (int_mode, 0, op1, op0,
1074                                         if_true_label, if_false_label,
1075                                         prob.invert ());
1076           break;
1077
1078         case EQ:
1079           do_jump_by_parts_equality_rtx (int_mode, op0, op1, if_false_label,
1080                                          if_true_label, prob);
1081           break;
1082
1083         case NE:
1084           do_jump_by_parts_equality_rtx (int_mode, op0, op1, if_true_label,
1085                                          if_false_label,
1086                                          prob.invert ());
1087           break;
1088
1089         default:
1090           gcc_unreachable ();
1091         }
1092     }
1093   else
1094     {
1095       if (SCALAR_FLOAT_MODE_P (mode)
1096           && ! can_compare_p (code, mode, ccp_jump)
1097           && can_compare_p (swap_condition (code), mode, ccp_jump))
1098         {
1099           code = swap_condition (code);
1100           std::swap (op0, op1);
1101         }
1102       else if (SCALAR_FLOAT_MODE_P (mode)
1103                && ! can_compare_p (code, mode, ccp_jump)
1104                /* Never split ORDERED and UNORDERED.
1105                   These must be implemented.  */
1106                && (code != ORDERED && code != UNORDERED)
1107                /* Split a floating-point comparison if
1108                   we can jump on other conditions...  */
1109                && (have_insn_for (COMPARE, mode)
1110                    /* ... or if there is no libcall for it.  */
1111                    || code_to_optab (code) == unknown_optab))
1112         {
1113           enum rtx_code first_code;
1114           bool and_them = split_comparison (code, mode, &first_code, &code);
1115
1116           /* If there are no NaNs, the first comparison should always fall
1117              through.  */
1118           if (!HONOR_NANS (mode))
1119             gcc_assert (first_code == (and_them ? ORDERED : UNORDERED));
1120
1121           else
1122             {
1123               profile_probability first_prob = prob;
1124               if (first_code == UNORDERED)
1125                 first_prob = profile_probability::guessed_always ().apply_scale
1126                                  (1, 100);
1127               else if (first_code == ORDERED)
1128                 first_prob = profile_probability::guessed_always ().apply_scale
1129                                  (99, 100);
1130               if (and_them)
1131                 {
1132                   rtx_code_label *dest_label;
1133                   /* If we only jump if true, just bypass the second jump.  */
1134                   if (! if_false_label)
1135                     {
1136                       if (! dummy_label)
1137                         dummy_label = gen_label_rtx ();
1138                       dest_label = dummy_label;
1139                     }
1140                   else
1141                     dest_label = if_false_label;
1142                   do_compare_rtx_and_jump (op0, op1, first_code, unsignedp, mode,
1143                                            size, dest_label, NULL, first_prob);
1144                 }
1145               else
1146                 do_compare_rtx_and_jump (op0, op1, first_code, unsignedp, mode,
1147                                          size, NULL, if_true_label, first_prob);
1148             }
1149         }
1150
1151       emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp,
1152                                if_true_label, prob);
1153     }
1154
1155   if (if_false_label)
1156     emit_jump (if_false_label);
1157   if (dummy_label)
1158     emit_label (dummy_label);
1159 }
1160
1161 /* Generate code for a comparison expression EXP (including code to compute
1162    the values to be compared) and a conditional jump to IF_FALSE_LABEL and/or
1163    IF_TRUE_LABEL.  One of the labels can be NULL_RTX, in which case the
1164    generated code will drop through.
1165    SIGNED_CODE should be the rtx operation for this comparison for
1166    signed data; UNSIGNED_CODE, likewise for use if data is unsigned.
1167
1168    We force a stack adjustment unless there are currently
1169    things pushed on the stack that aren't yet used.  */
1170
1171 static void
1172 do_compare_and_jump (tree treeop0, tree treeop1, enum rtx_code signed_code,
1173                      enum rtx_code unsigned_code,
1174                      rtx_code_label *if_false_label,
1175                      rtx_code_label *if_true_label, profile_probability prob)
1176 {
1177   rtx op0, op1;
1178   tree type;
1179   machine_mode mode;
1180   int unsignedp;
1181   enum rtx_code code;
1182
1183   /* Don't crash if the comparison was erroneous.  */
1184   op0 = expand_normal (treeop0);
1185   if (TREE_CODE (treeop0) == ERROR_MARK)
1186     return;
1187
1188   op1 = expand_normal (treeop1);
1189   if (TREE_CODE (treeop1) == ERROR_MARK)
1190     return;
1191
1192   type = TREE_TYPE (treeop0);
1193   if (TREE_CODE (treeop0) == INTEGER_CST
1194       && (TREE_CODE (treeop1) != INTEGER_CST
1195           || (GET_MODE_BITSIZE (SCALAR_INT_TYPE_MODE (type))
1196               > GET_MODE_BITSIZE (SCALAR_INT_TYPE_MODE (TREE_TYPE (treeop1))))))
1197     /* op0 might have been replaced by promoted constant, in which
1198        case the type of second argument should be used.  */
1199     type = TREE_TYPE (treeop1);
1200   mode = TYPE_MODE (type);
1201   unsignedp = TYPE_UNSIGNED (type);
1202   code = unsignedp ? unsigned_code : signed_code;
1203
1204   /* If function pointers need to be "canonicalized" before they can
1205      be reliably compared, then canonicalize them.
1206      Only do this if *both* sides of the comparison are function pointers.
1207      If one side isn't, we want a noncanonicalized comparison.  See PR
1208      middle-end/17564.  */
1209   if (targetm.have_canonicalize_funcptr_for_compare ()
1210       && POINTER_TYPE_P (TREE_TYPE (treeop0))
1211       && POINTER_TYPE_P (TREE_TYPE (treeop1))
1212       && FUNC_OR_METHOD_TYPE_P (TREE_TYPE (TREE_TYPE (treeop0)))
1213       && FUNC_OR_METHOD_TYPE_P (TREE_TYPE (TREE_TYPE (treeop1))))
1214     {
1215       rtx new_op0 = gen_reg_rtx (mode);
1216       rtx new_op1 = gen_reg_rtx (mode);
1217
1218       emit_insn (targetm.gen_canonicalize_funcptr_for_compare (new_op0, op0));
1219       op0 = new_op0;
1220
1221       emit_insn (targetm.gen_canonicalize_funcptr_for_compare (new_op1, op1));
1222       op1 = new_op1;
1223     }
1224
1225   do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode,
1226                            ((mode == BLKmode)
1227                             ? expr_size (treeop0) : NULL_RTX),
1228                            if_false_label, if_true_label, prob);
1229 }
1230
1231 #include "gt-dojump.h"