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/* Convert tree expression to rtl instructions, for GNU compiler.

   Copyright (C) 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,

   2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 2, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING.  If not, write to the Free

Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "rtl.h"

#include "tree.h"

#include "flags.h"

#include "function.h"

#include "insn-config.h"

#include "insn-attr.h"

/* Include expr.h after insn-config.h so we get HAVE_conditional_move.  */

#include "expr.h"

#include "optabs.h"

#include "langhooks.h"

#include "ggc.h"

static bool prefer_and_bit_test (enum machine_mode, int);

static void do_jump_by_parts_greater (tree, int, rtx, rtx);

static void do_jump_by_parts_equality (tree, rtx, rtx);

static void do_compare_and_jump (tree, enum rtx_code, enum rtx_code, rtx,

                                 rtx);

/* At the start of a function, record that we have no previously-pushed

   arguments waiting to be popped.  */

void

init_pending_stack_adjust (void)

{

  pending_stack_adjust = 0;

}

/* Discard any pending stack adjustment.  This avoid relying on the

   RTL optimizers to remove useless adjustments when we know the

   stack pointer value is dead.  */

void discard_pending_stack_adjust (void)

{

  stack_pointer_delta -= pending_stack_adjust;

  pending_stack_adjust = 0;

}

/* When exiting from function, if safe, clear out any pending stack adjust

   so the adjustment won't get done.

   Note, if the current function calls alloca, then it must have a

   frame pointer regardless of the value of flag_omit_frame_pointer.  */

void

clear_pending_stack_adjust (void)

{

  if (optimize > 0

      && (! flag_omit_frame_pointer || current_function_calls_alloca)

      && EXIT_IGNORE_STACK

      && ! (DECL_INLINE (current_function_decl) && ! flag_no_inline))

    discard_pending_stack_adjust ();

}

/* Pop any previously-pushed arguments that have not been popped yet.  */

void

do_pending_stack_adjust (void)

{

  if (inhibit_defer_pop == 0)

    {

      if (pending_stack_adjust != 0)

        adjust_stack (GEN_INT (pending_stack_adjust));

      pending_stack_adjust = 0;

    }

}

/* Expand conditional expressions.  */

/* Generate code to evaluate EXP and jump to LABEL if the value is zero.

   LABEL is an rtx of code CODE_LABEL, in this function and all the

   functions here.  */

void

jumpifnot (tree exp, rtx label)

{

  do_jump (exp, label, NULL_RTX);

}

/* Generate code to evaluate EXP and jump to LABEL if the value is nonzero.  */

void

jumpif (tree exp, rtx label)

{

  do_jump (exp, NULL_RTX, label);

}

/* Used internally by prefer_and_bit_test.  */

static GTY(()) rtx and_reg;

static GTY(()) rtx and_test;

static GTY(()) rtx shift_test;

/* Compare the relative costs of "(X & (1 << BITNUM))" and "(X >> BITNUM) & 1",

   where X is an arbitrary register of mode MODE.  Return true if the former

   is preferred.  */

static bool

prefer_and_bit_test (enum machine_mode mode, int bitnum)

{

  if (and_test == 0)

    {

      /* Set up rtxes for the two variations.  Use NULL as a placeholder

         for the BITNUM-based constants.  */

      and_reg = gen_rtx_REG (mode, FIRST_PSEUDO_REGISTER);

      and_test = gen_rtx_AND (mode, and_reg, NULL);

      shift_test = gen_rtx_AND (mode, gen_rtx_ASHIFTRT (mode, and_reg, NULL),

                                const1_rtx);

    }

  else

    {

      /* Change the mode of the previously-created rtxes.  */

      PUT_MODE (and_reg, mode);

      PUT_MODE (and_test, mode);

      PUT_MODE (shift_test, mode);

      PUT_MODE (XEXP (shift_test, 0), mode);

    }

  /* Fill in the integers.  */

  XEXP (and_test, 1) = GEN_INT ((unsigned HOST_WIDE_INT) 1 << bitnum);

  XEXP (XEXP (shift_test, 0), 1) = GEN_INT (bitnum);

  return (rtx_cost (and_test, IF_THEN_ELSE)

          <= rtx_cost (shift_test, IF_THEN_ELSE));

}

/* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if

   the result is zero, or IF_TRUE_LABEL if the result is one.

   Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero,

   meaning fall through in that case.

   do_jump always does any pending stack adjust except when it does not

   actually perform a jump.  An example where there is no jump

   is when EXP is `(foo (), 0)' and IF_FALSE_LABEL is null.  */

void

do_jump (tree exp, rtx if_false_label, rtx if_true_label)

{

  enum tree_code code = TREE_CODE (exp);

  rtx temp;

  int i;

  tree type;

  enum machine_mode mode;

  rtx drop_through_label = 0;

  switch (code)

    {

    case ERROR_MARK:

      break;

    case INTEGER_CST:

      temp = integer_zerop (exp) ? if_false_label : if_true_label;

      if (temp)

        emit_jump (temp);

      break;

#if 0

      /* This is not true with #pragma weak  */

    case ADDR_EXPR:

      /* The address of something can never be zero.  */

      if (if_true_label)

        emit_jump (if_true_label);

      break;

#endif

    case NOP_EXPR:

      if (TREE_CODE (TREE_OPERAND (exp, 0)) == COMPONENT_REF

          || TREE_CODE (TREE_OPERAND (exp, 0)) == BIT_FIELD_REF

          || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF

          || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_RANGE_REF)

        goto normal;

    case CONVERT_EXPR:

      /* If we are narrowing the operand, we have to do the compare in the

         narrower mode.  */

      if ((TYPE_PRECISION (TREE_TYPE (exp))

           < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))

        goto normal;

    case NON_LVALUE_EXPR:

    case ABS_EXPR:

    case NEGATE_EXPR:

    case LROTATE_EXPR:

    case RROTATE_EXPR:

      /* These cannot change zero->nonzero or vice versa.  */

      do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);

      break;

    case BIT_AND_EXPR:

      /* fold_single_bit_test() converts (X & (1 << C)) into (X >> C) & 1.

         See if the former is preferred for jump tests and restore it

         if so.  */

      if (integer_onep (TREE_OPERAND (exp, 1)))

        {

          tree exp0 = TREE_OPERAND (exp, 0);

          rtx set_label, clr_label;

          /* Strip narrowing integral type conversions.  */

          while ((TREE_CODE (exp0) == NOP_EXPR

                  || TREE_CODE (exp0) == CONVERT_EXPR

                  || TREE_CODE (exp0) == NON_LVALUE_EXPR)

                 && TREE_OPERAND (exp0, 0) != error_mark_node

                 && TYPE_PRECISION (TREE_TYPE (exp0))

                    <= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp0, 0))))

            exp0 = TREE_OPERAND (exp0, 0);

          /* "exp0 ^ 1" inverts the sense of the single bit test.  */

          if (TREE_CODE (exp0) == BIT_XOR_EXPR

              && integer_onep (TREE_OPERAND (exp0, 1)))

            {

              exp0 = TREE_OPERAND (exp0, 0);

              clr_label = if_true_label;

              set_label = if_false_label;

            }

          else

            {

              clr_label = if_false_label;

              set_label = if_true_label;

            }

          if (TREE_CODE (exp0) == RSHIFT_EXPR)

            {

              tree arg = TREE_OPERAND (exp0, 0);

              tree shift = TREE_OPERAND (exp0, 1);

              tree argtype = TREE_TYPE (arg);

              if (TREE_CODE (shift) == INTEGER_CST

                  && compare_tree_int (shift, 0) >= 0

                  && compare_tree_int (shift, HOST_BITS_PER_WIDE_INT) < 0

                  && prefer_and_bit_test (TYPE_MODE (argtype),

                                          TREE_INT_CST_LOW (shift)))

                {

                  HOST_WIDE_INT mask = (HOST_WIDE_INT) 1

                                       << TREE_INT_CST_LOW (shift);

                  do_jump (build2 (BIT_AND_EXPR, argtype, arg,

                                   build_int_cst_type (argtype, mask)),

                           clr_label, set_label);

                  break;

                }

            }

        }

      /* If we are AND'ing with a small constant, do this comparison in the

         smallest type that fits.  If the machine doesn't have comparisons

         that small, it will be converted back to the wider comparison.

         This helps if we are testing the sign bit of a narrower object.

         combine can't do this for us because it can't know whether a

         ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */

      if (! SLOW_BYTE_ACCESS

          && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST

          && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT

          && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0

          && (mode = mode_for_size (i + 1, MODE_INT, 0)) != BLKmode

          && (type = lang_hooks.types.type_for_mode (mode, 1)) != 0

          && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))

          && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code

              != CODE_FOR_nothing))

        {

          do_jump (convert (type, exp), if_false_label, if_true_label);

          break;

        }

      goto normal;

    case TRUTH_NOT_EXPR:

      do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);

      break;

    case COND_EXPR:

      {

        rtx label1 = gen_label_rtx ();

        if (!if_true_label || !if_false_label)

          {

            drop_through_label = gen_label_rtx ();

            if (!if_true_label)

              if_true_label = drop_through_label;

            if (!if_false_label)

              if_false_label = drop_through_label;

          }

        do_pending_stack_adjust ();

        do_jump (TREE_OPERAND (exp, 0), label1, NULL_RTX);

        do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);

        emit_label (label1);

        do_jump (TREE_OPERAND (exp, 2), if_false_label, if_true_label);

        break;

      }

    case TRUTH_ANDIF_EXPR:

    case TRUTH_ORIF_EXPR:

    case COMPOUND_EXPR:

      /* Lowered by gimplify.c.  */

      gcc_unreachable ();

    case COMPONENT_REF:

    case BIT_FIELD_REF:

    case ARRAY_REF:

    case ARRAY_RANGE_REF:

      {

        HOST_WIDE_INT bitsize, bitpos;

        int unsignedp;

        enum machine_mode mode;

        tree type;

        tree offset;

        int volatilep = 0;

        /* Get description of this reference.  We don't actually care

           about the underlying object here.  */

        get_inner_reference (exp, &bitsize, &bitpos, &offset, &mode,

                             &unsignedp, &volatilep, false);

        type = lang_hooks.types.type_for_size (bitsize, unsignedp);

        if (! SLOW_BYTE_ACCESS

            && type != 0 && bitsize >= 0

            && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))

            && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code

                != CODE_FOR_nothing))

          {

            do_jump (convert (type, exp), if_false_label, if_true_label);

            break;

          }

        goto normal;

      }

    case EQ_EXPR:

      {

        tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));

        gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))

                    != MODE_COMPLEX_FLOAT);

        gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))

                    != MODE_COMPLEX_INT);

        if (integer_zerop (TREE_OPERAND (exp, 1)))

          do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);

        else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT

                 && !can_compare_p (EQ, TYPE_MODE (inner_type), ccp_jump))

          do_jump_by_parts_equality (exp, if_false_label, if_true_label);

        else

          do_compare_and_jump (exp, EQ, EQ, if_false_label, if_true_label);

        break;

      }

    case MINUS_EXPR:

      /* Nonzero iff operands of minus differ.  */

      exp = build2 (NE_EXPR, TREE_TYPE (exp),

                    TREE_OPERAND (exp, 0),

                    TREE_OPERAND (exp, 1));

      /* FALLTHRU */

    case NE_EXPR:

      {

        tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));

        gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))

                    != MODE_COMPLEX_FLOAT);

        gcc_assert (GET_MODE_CLASS (TYPE_MODE (inner_type))

                    != MODE_COMPLEX_INT);

        if (integer_zerop (TREE_OPERAND (exp, 1)))

          do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);

        else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT

           && !can_compare_p (NE, TYPE_MODE (inner_type), ccp_jump))

          do_jump_by_parts_equality (exp, if_true_label, if_false_label);

        else

          do_compare_and_jump (exp, NE, NE, if_false_label, if_true_label);

        break;

      }

    case LT_EXPR:

      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));

      if (GET_MODE_CLASS (mode) == MODE_INT

          && ! can_compare_p (LT, mode, ccp_jump))

        do_jump_by_parts_greater (exp, 1, if_false_label, if_true_label);

      else

        do_compare_and_jump (exp, LT, LTU, if_false_label, if_true_label);

      break;

    case LE_EXPR:

      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));

      if (GET_MODE_CLASS (mode) == MODE_INT

          && ! can_compare_p (LE, mode, ccp_jump))

        do_jump_by_parts_greater (exp, 0, if_true_label, if_false_label);

      else

        do_compare_and_jump (exp, LE, LEU, if_false_label, if_true_label);

      break;

    case GT_EXPR:

      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));

      if (GET_MODE_CLASS (mode) == MODE_INT

          && ! can_compare_p (GT, mode, ccp_jump))

        do_jump_by_parts_greater (exp, 0, if_false_label, if_true_label);

      else

        do_compare_and_jump (exp, GT, GTU, if_false_label, if_true_label);

      break;

    case GE_EXPR:

      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));

      if (GET_MODE_CLASS (mode) == MODE_INT

          && ! can_compare_p (GE, mode, ccp_jump))

        do_jump_by_parts_greater (exp, 1, if_true_label, if_false_label);

      else

        do_compare_and_jump (exp, GE, GEU, if_false_label, if_true_label);

      break;

    case UNORDERED_EXPR:

    case ORDERED_EXPR:

      {

        enum rtx_code cmp, rcmp;

        int do_rev;

        if (code == UNORDERED_EXPR)

          cmp = UNORDERED, rcmp = ORDERED;

        else

          cmp = ORDERED, rcmp = UNORDERED;

        mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));

        do_rev = 0;

        if (! can_compare_p (cmp, mode, ccp_jump)

            && (can_compare_p (rcmp, mode, ccp_jump)

          /* If the target doesn't provide either UNORDERED or ORDERED

             comparisons, canonicalize on UNORDERED for the library.  */

          || rcmp == UNORDERED))

          do_rev = 1;

        if (! do_rev)

          do_compare_and_jump (exp, cmp, cmp, if_false_label, if_true_label);

        else

          do_compare_and_jump (exp, rcmp, rcmp, if_true_label, if_false_label);

      }

      break;

    {

      enum rtx_code rcode1;

      enum tree_code tcode1, tcode2;

      case UNLT_EXPR:

        rcode1 = UNLT;

        tcode1 = UNORDERED_EXPR;

        tcode2 = LT_EXPR;

        goto unordered_bcc;

      case UNLE_EXPR:

        rcode1 = UNLE;

        tcode1 = UNORDERED_EXPR;

        tcode2 = LE_EXPR;

        goto unordered_bcc;

      case UNGT_EXPR:

        rcode1 = UNGT;

        tcode1 = UNORDERED_EXPR;

        tcode2 = GT_EXPR;

        goto unordered_bcc;

      case UNGE_EXPR:

        rcode1 = UNGE;

        tcode1 = UNORDERED_EXPR;

        tcode2 = GE_EXPR;

        goto unordered_bcc;

      case UNEQ_EXPR:

        rcode1 = UNEQ;

        tcode1 = UNORDERED_EXPR;

        tcode2 = EQ_EXPR;

        goto unordered_bcc;

      case LTGT_EXPR:

        /* It is ok for LTGT_EXPR to trap when the result is unordered,

           so expand to (a < b) || (a > b).  */

        rcode1 = LTGT;

        tcode1 = LT_EXPR;

        tcode2 = GT_EXPR;

        goto unordered_bcc;

      unordered_bcc:

        mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));

        if (can_compare_p (rcode1, mode, ccp_jump))

          do_compare_and_jump (exp, rcode1, rcode1, if_false_label,

                               if_true_label);

        else

          {

            tree op0 = save_expr (TREE_OPERAND (exp, 0));

            tree op1 = save_expr (TREE_OPERAND (exp, 1));

            tree cmp0, cmp1;

            /* If the target doesn't support combined unordered

               compares, decompose into two comparisons.  */

            if (if_true_label == 0)

              drop_through_label = if_true_label = gen_label_rtx ();

            cmp0 = fold_build2 (tcode1, TREE_TYPE (exp), op0, op1);

            cmp1 = fold_build2 (tcode2, TREE_TYPE (exp), op0, op1);

            do_jump (cmp0, 0, if_true_label);

            do_jump (cmp1, if_false_label, if_true_label);

          }

      }

      break;

    case TRUTH_AND_EXPR:

      /* High branch cost, expand as the bitwise AND of the conditions.

         Do the same if the RHS has side effects, because we're effectively

         turning a TRUTH_AND_EXPR into a TRUTH_ANDIF_EXPR.  */

      if (BRANCH_COST >= 4 || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))

        goto normal;

      if (if_false_label == NULL_RTX)

        {

          drop_through_label = gen_label_rtx ();

          do_jump (TREE_OPERAND (exp, 0), drop_through_label, NULL_RTX);

          do_jump (TREE_OPERAND (exp, 1), NULL_RTX, if_true_label);

        }

      else

        {

          do_jump (TREE_OPERAND (exp, 0), if_false_label, NULL_RTX);

          do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);

        }

      break;

    case TRUTH_OR_EXPR:

      /* High branch cost, expand as the bitwise OR of the conditions.

         Do the same if the RHS has side effects, because we're effectively

         turning a TRUTH_OR_EXPR into a TRUTH_ORIF_EXPR.  */

      if (BRANCH_COST >= 4 || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))

        goto normal;

      if (if_true_label == NULL_RTX)

        {

          drop_through_label = gen_label_rtx ();

          do_jump (TREE_OPERAND (exp, 0), NULL_RTX, drop_through_label);

          do_jump (TREE_OPERAND (exp, 1), if_false_label, NULL_RTX);

        }

      else

        {

          do_jump (TREE_OPERAND (exp, 0), NULL_RTX, if_true_label);

          do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);

        }

      break;

      /* Special case:

          __builtin_expect (<test>, 0)  and

          __builtin_expect (<test>, 1)

         We need to do this here, so that <test> is not converted to a SCC

         operation on machines that use condition code registers and COMPARE

         like the PowerPC, and then the jump is done based on whether the SCC

         operation produced a 1 or 0.  */

    case CALL_EXPR:

      /* Check for a built-in function.  */

      {

        tree fndecl = get_callee_fndecl (exp);

        tree arglist = TREE_OPERAND (exp, 1);

        if (fndecl

            && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL

            && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT

            && arglist != NULL_TREE

            && TREE_CHAIN (arglist) != NULL_TREE)

          {

            rtx seq = expand_builtin_expect_jump (exp, if_false_label,

                                                  if_true_label);

            if (seq != NULL_RTX)

              {

                emit_insn (seq);

                return;

              }

          }

      }

      /* Fall through and generate the normal code.  */

    default:

    normal:

      temp = expand_expr (exp, NULL_RTX, VOIDmode, 0);

      do_pending_stack_adjust ();

      if (GET_CODE (temp) == CONST_INT

          || (GET_CODE (temp) == CONST_DOUBLE && GET_MODE (temp) == VOIDmode)

          || GET_CODE (temp) == LABEL_REF)

        {

          rtx target = temp == const0_rtx ? if_false_label : if_true_label;

          if (target)

            emit_jump (target);

        }

      else if (GET_MODE_CLASS (GET_MODE (temp)) == MODE_INT

               && ! can_compare_p (NE, GET_MODE (temp), ccp_jump))

        /* Note swapping the labels gives us not-equal.  */

        do_jump_by_parts_equality_rtx (temp, if_true_label, if_false_label);

      else

        {

          gcc_assert (GET_MODE (temp) != VOIDmode);

          /* The RTL optimizers prefer comparisons against pseudos.  */

          if (GET_CODE (temp) == SUBREG)

            {

              /* Compare promoted variables in their promoted mode.  */

              if (SUBREG_PROMOTED_VAR_P (temp)

                  && REG_P (XEXP (temp, 0)))

                temp = XEXP (temp, 0);

              else

                temp = copy_to_reg (temp);

            }

          do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),

                                   NE, TYPE_UNSIGNED (TREE_TYPE (exp)),

                                   GET_MODE (temp), NULL_RTX,

                                   if_false_label, if_true_label);

        }

    }

  if (drop_through_label)

    {

      do_pending_stack_adjust ();

      emit_label (drop_through_label);

    }

}

/* Given a comparison expression EXP for values too wide to be compared

   with one insn, test the comparison and jump to the appropriate label.

   The code of EXP is ignored; we always test GT if SWAP is 0,

   and LT if SWAP is 1.  */

static void

do_jump_by_parts_greater (tree exp, int swap, rtx if_false_label,

                          rtx if_true_label)

{

  rtx op0 = expand_expr (TREE_OPERAND (exp, swap), NULL_RTX, VOIDmode, 0);

  rtx op1 = expand_expr (TREE_OPERAND (exp, !swap), NULL_RTX, VOIDmode, 0);

  enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));

  int unsignedp = TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)));

  do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label,

                                if_true_label);

}

/* Compare OP0 with OP1, word at a time, in mode MODE.

   UNSIGNEDP says to do unsigned comparison.

   Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */

void

do_jump_by_parts_greater_rtx (enum machine_mode mode, int unsignedp, rtx op0,

                              rtx op1, rtx if_false_label, rtx if_true_label)

{

  int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);

  rtx drop_through_label = 0;

  int i;

  if (! if_true_label || ! if_false_label)

    drop_through_label = gen_label_rtx ();

  if (! if_true_label)

    if_true_label = drop_through_label;

  if (! if_false_label)

    if_false_label = drop_through_label;

  /* Compare a word at a time, high order first.  */

  for (i = 0; i < nwords; i++)

    {