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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, 2006, 2007, 2008, 2009, 2010

   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 3, 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 COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#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"

#include "basic-block.h"

#include "output.h"

static bool prefer_and_bit_test (enum machine_mode, int);

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

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

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

                                 rtx, int);

/* Invert probability if there is any.  -1 stands for unknown.  */

static inline int

inv (int prob)

{

  return prob == -1 ? -1 : REG_BR_PROB_BASE - prob;

}

/* 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 || cfun->calls_alloca)

      && EXIT_IGNORE_STACK)

    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, int prob)

{

  do_jump (exp, label, NULL_RTX, inv (prob));

}

void

jumpifnot_1 (enum tree_code code, tree op0, tree op1, rtx label, int prob)

{

  do_jump_1 (code, op0, op1, label, NULL_RTX, inv (prob));

}

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

void

jumpif (tree exp, rtx label, int prob)

{

  do_jump (exp, NULL_RTX, label, prob);

}

void

jumpif_1 (enum tree_code code, tree op0, tree op1, rtx label, int prob)

{

  do_jump_1 (code, op0, op1, NULL_RTX, label, prob);

}

/* 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)

    = immed_double_const ((unsigned HOST_WIDE_INT) 1 << bitnum, 0, mode);

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

  return (rtx_cost (and_test, IF_THEN_ELSE, optimize_insn_for_speed_p ())

          <= rtx_cost (shift_test, IF_THEN_ELSE, optimize_insn_for_speed_p ()));

}

/* Subroutine of do_jump, dealing with exploded comparisons of the type

   OP0 CODE OP1 .  IF_FALSE_LABEL and IF_TRUE_LABEL like in do_jump.

   PROB is probability of jump to if_true_label, or -1 if unknown.  */

void

do_jump_1 (enum tree_code code, tree op0, tree op1,

           rtx if_false_label, rtx if_true_label, int prob)

{

  enum machine_mode mode;

  rtx drop_through_label = 0;

  switch (code)

    {

    case EQ_EXPR:

      {

        tree inner_type = TREE_TYPE (op0);

        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 (op1))

          do_jump (op0, if_true_label, if_false_label, inv (prob));

        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 (op0, op1, if_false_label, if_true_label,

                                     prob);

        else

          do_compare_and_jump (op0, op1, EQ, EQ, if_false_label, if_true_label,

                               prob);

        break;

      }

    case NE_EXPR:

      {

        tree inner_type = TREE_TYPE (op0);

        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 (op1))

          do_jump (op0, if_false_label, if_true_label, prob);

        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 (op0, op1, if_true_label, if_false_label,

                                     inv (prob));

        else

          do_compare_and_jump (op0, op1, NE, NE, if_false_label, if_true_label,

                               prob);

        break;

      }

    case LT_EXPR:

      mode = TYPE_MODE (TREE_TYPE (op0));

      if (GET_MODE_CLASS (mode) == MODE_INT

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

        do_jump_by_parts_greater (op0, op1, 1, if_false_label, if_true_label,

                                  prob);

      else

        do_compare_and_jump (op0, op1, LT, LTU, if_false_label, if_true_label,

                             prob);

      break;

    case LE_EXPR:

      mode = TYPE_MODE (TREE_TYPE (op0));

      if (GET_MODE_CLASS (mode) == MODE_INT

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

        do_jump_by_parts_greater (op0, op1, 0, if_true_label, if_false_label,

                                  inv (prob));

      else

        do_compare_and_jump (op0, op1, LE, LEU, if_false_label, if_true_label,

                             prob);

      break;

    case GT_EXPR:

      mode = TYPE_MODE (TREE_TYPE (op0));

      if (GET_MODE_CLASS (mode) == MODE_INT

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

        do_jump_by_parts_greater (op0, op1, 0, if_false_label, if_true_label,

                                  prob);

      else

        do_compare_and_jump (op0, op1, GT, GTU, if_false_label, if_true_label,

                             prob);

      break;

    case GE_EXPR:

      mode = TYPE_MODE (TREE_TYPE (op0));

      if (GET_MODE_CLASS (mode) == MODE_INT

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

        do_jump_by_parts_greater (op0, op1, 1, if_true_label, if_false_label,

                                  inv (prob));

      else

        do_compare_and_jump (op0, op1, GE, GEU, if_false_label, if_true_label,

                             prob);

      break;

    case ORDERED_EXPR:

      do_compare_and_jump (op0, op1, ORDERED, ORDERED,

                           if_false_label, if_true_label, prob);

      break;

    case UNORDERED_EXPR:

      do_compare_and_jump (op0, op1, UNORDERED, UNORDERED,

                           if_false_label, if_true_label, prob);

      break;

    case UNLT_EXPR:

      do_compare_and_jump (op0, op1, UNLT, UNLT, if_false_label, if_true_label,

                           prob);

      break;

    case UNLE_EXPR:

      do_compare_and_jump (op0, op1, UNLE, UNLE, if_false_label, if_true_label,

                           prob);

      break;

    case UNGT_EXPR:

      do_compare_and_jump (op0, op1, UNGT, UNGT, if_false_label, if_true_label,

                           prob);

      break;

    case UNGE_EXPR:

      do_compare_and_jump (op0, op1, UNGE, UNGE, if_false_label, if_true_label,

                           prob);

      break;

    case UNEQ_EXPR:

      do_compare_and_jump (op0, op1, UNEQ, UNEQ, if_false_label, if_true_label,

                           prob);

      break;

    case LTGT_EXPR:

      do_compare_and_jump (op0, op1, LTGT, LTGT, if_false_label, if_true_label,

                           prob);

      break;

    case TRUTH_ANDIF_EXPR:

      if (if_false_label == NULL_RTX)

        {

          drop_through_label = gen_label_rtx ();

          do_jump (op0, drop_through_label, NULL_RTX, prob);

          do_jump (op1, NULL_RTX, if_true_label, prob);

        }

      else

        {

          do_jump (op0, if_false_label, NULL_RTX, prob);

          do_jump (op1, if_false_label, if_true_label, prob);

        }

      break;

    case TRUTH_ORIF_EXPR:

      if (if_true_label == NULL_RTX)

        {

          drop_through_label = gen_label_rtx ();

          do_jump (op0, NULL_RTX, drop_through_label, prob);

          do_jump (op1, if_false_label, NULL_RTX, prob);

        }

      else

        {

          do_jump (op0, NULL_RTX, if_true_label, prob);

          do_jump (op1, if_false_label, if_true_label, prob);

        }

      break;

    default:

      gcc_unreachable ();

    }

  if (drop_through_label)

    {

      do_pending_stack_adjust ();

      emit_label (drop_through_label);

    }

}

/* 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.

   PROB is probability of jump to if_true_label, or -1 if unknown.  */

void

do_jump (tree exp, rtx if_false_label, rtx if_true_label, int prob)

{

  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, prob);

      break;

    case TRUTH_NOT_EXPR:

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

               inv (prob));

      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, -1);

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

        emit_label (label1);

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

        break;

      }

    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))

            && have_insn_for (COMPARE, TYPE_MODE (type)))

          {

            do_jump (fold_convert (type, exp), if_false_label, if_true_label,

                     prob);

            break;

          }

        goto normal;

      }

    case MINUS_EXPR:

      /* Nonzero iff operands of minus differ.  */

      code = NE_EXPR;

      /* FALLTHRU */

    case EQ_EXPR:

    case NE_EXPR:

    case LT_EXPR:

    case LE_EXPR:

    case GT_EXPR:

    case GE_EXPR:

    case ORDERED_EXPR:

    case UNORDERED_EXPR:

    case UNLT_EXPR:

    case UNLE_EXPR:

    case UNGT_EXPR:

    case UNGE_EXPR:

    case UNEQ_EXPR:

    case LTGT_EXPR:

    case TRUTH_ANDIF_EXPR:

    case TRUTH_ORIF_EXPR:

    other_code:

      do_jump_1 (code, TREE_OPERAND (exp, 0), TREE_OPERAND (exp, 1),

                 if_false_label, if_true_label, prob);

      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;

          int setclr_prob = prob;

          /* Strip narrowing integral type conversions.  */

          while (CONVERT_EXPR_P (exp0)

                 && 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;

              setclr_prob = inv (prob);

            }

          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)))

                {

                  unsigned HOST_WIDE_INT mask

                    = (unsigned HOST_WIDE_INT) 1 << TREE_INT_CST_LOW (shift);

                  do_jump (build2 (BIT_AND_EXPR, argtype, arg,

                                   build_int_cst_wide_type (argtype, mask, 0)),

                           clr_label, set_label, setclr_prob);

                  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))

          && have_insn_for (COMPARE, TYPE_MODE (type)))

        {

          do_jump (fold_convert (type, exp), if_false_label, if_true_label,

                   prob);

          break;

        }

      if (TYPE_PRECISION (TREE_TYPE (exp)) > 1

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

        goto normal;

      /* Boolean comparisons can be compiled as TRUTH_AND_EXPR.  */

    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 (optimize_insn_for_speed_p (),

                       false) >= 4

          || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))

        goto normal;

      code = TRUTH_ANDIF_EXPR;

      goto other_code;

    case BIT_IOR_EXPR:

    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 (optimize_insn_for_speed_p (), false) >= 4

          || TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))

        goto normal;

      code = TRUTH_ORIF_EXPR;

      goto other_code;

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

    default:

    normal:

      temp = expand_normal (exp);

      do_pending_stack_adjust ();

      /* 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, prob);

    }

  if (drop_through_label)

    {

      do_pending_stack_adjust ();

      emit_label (drop_through_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.  */

static 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 prob)

{

  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++)

    {

      rtx op0_word, op1_word;

      if (WORDS_BIG_ENDIAN)

        {

          op0_word = operand_subword_force (op0, i, mode);

          op1_word = operand_subword_force (op1, i, mode);

        }

      else

        {

          op0_word = operand_subword_force (op0, nwords - 1 - i, mode);

          op1_word = operand_subword_force (op1, nwords - 1 - i, mode);

        }

      /* All but high-order word must be compared as unsigned.  */

      do_compare_rtx_and_jump (op0_word, op1_word, GT,

                               (unsignedp || i > 0), word_mode, NULL_RTX,

                               NULL_RTX, if_true_label, prob);

      /* Consider lower words only if these are equal.  */

      do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,

                               NULL_RTX, NULL_RTX, if_false_label,

                               inv (prob));

    }

  if (if_false_label)

    emit_jump (if_false_label);

  if (drop_through_label)

    emit_label (drop_through_label);