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/* Definitions for computing resource usage of specific insns.

   Copyright (C) 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 "diagnostic-core.h"

#include "rtl.h"

#include "tm_p.h"

#include "hard-reg-set.h"

#include "function.h"

#include "regs.h"

#include "flags.h"

#include "output.h"

#include "resource.h"

#include "except.h"

#include "insn-attr.h"

#include "params.h"

#include "df.h"

/* This structure is used to record liveness information at the targets or

   fallthrough insns of branches.  We will most likely need the information

   at targets again, so save them in a hash table rather than recomputing them

   each time.  */

struct target_info

{

  int uid;                      /* INSN_UID of target.  */

  struct target_info *next;     /* Next info for same hash bucket.  */

  HARD_REG_SET live_regs;       /* Registers live at target.  */

  int block;                    /* Basic block number containing target.  */

  int bb_tick;                  /* Generation count of basic block info.  */

};

#define TARGET_HASH_PRIME 257

/* Indicates what resources are required at the beginning of the epilogue.  */

static struct resources start_of_epilogue_needs;

/* Indicates what resources are required at function end.  */

static struct resources end_of_function_needs;

/* Define the hash table itself.  */

static struct target_info **target_hash_table = NULL;

/* For each basic block, we maintain a generation number of its basic

   block info, which is updated each time we move an insn from the

   target of a jump.  This is the generation number indexed by block

   number.  */

static int *bb_ticks;

/* Marks registers possibly live at the current place being scanned by

   mark_target_live_regs.  Also used by update_live_status.  */

static HARD_REG_SET current_live_regs;

/* Marks registers for which we have seen a REG_DEAD note but no assignment.

   Also only used by the next two functions.  */

static HARD_REG_SET pending_dead_regs;

static void update_live_status (rtx, const_rtx, void *);

static int find_basic_block (rtx, int);

static rtx next_insn_no_annul (rtx);

static rtx find_dead_or_set_registers (rtx, struct resources*,

                                       rtx*, int, struct resources,

                                       struct resources);

/* Utility function called from mark_target_live_regs via note_stores.

   It deadens any CLOBBERed registers and livens any SET registers.  */

static void

update_live_status (rtx dest, const_rtx x, void *data ATTRIBUTE_UNUSED)

{

  int first_regno, last_regno;

  int i;

  if (!REG_P (dest)

      && (GET_CODE (dest) != SUBREG || !REG_P (SUBREG_REG (dest))))

    return;

  if (GET_CODE (dest) == SUBREG)

    {

      first_regno = subreg_regno (dest);

      last_regno = first_regno + subreg_nregs (dest);

    }

  else

    {

      first_regno = REGNO (dest);

      last_regno = END_HARD_REGNO (dest);

    }

  if (GET_CODE (x) == CLOBBER)

    for (i = first_regno; i < last_regno; i++)

      CLEAR_HARD_REG_BIT (current_live_regs, i);

  else

    for (i = first_regno; i < last_regno; i++)

      {

        SET_HARD_REG_BIT (current_live_regs, i);

        CLEAR_HARD_REG_BIT (pending_dead_regs, i);

      }

}

/* Find the number of the basic block with correct live register

   information that starts closest to INSN.  Return -1 if we couldn't

   find such a basic block or the beginning is more than

   SEARCH_LIMIT instructions before INSN.  Use SEARCH_LIMIT = -1 for

   an unlimited search.

   The delay slot filling code destroys the control-flow graph so,

   instead of finding the basic block containing INSN, we search

   backwards toward a BARRIER where the live register information is

   correct.  */

static int

find_basic_block (rtx insn, int search_limit)

{

  /* Scan backwards to the previous BARRIER.  Then see if we can find a

     label that starts a basic block.  Return the basic block number.  */

  for (insn = prev_nonnote_insn (insn);

       insn && !BARRIER_P (insn) && search_limit != 0;

       insn = prev_nonnote_insn (insn), --search_limit)

    ;

  /* The closest BARRIER is too far away.  */

  if (search_limit == 0)

    return -1;

  /* The start of the function.  */

  else if (insn == 0)

    return ENTRY_BLOCK_PTR->next_bb->index;

  /* See if any of the upcoming CODE_LABELs start a basic block.  If we reach

     anything other than a CODE_LABEL or note, we can't find this code.  */

  for (insn = next_nonnote_insn (insn);

       insn && LABEL_P (insn);

       insn = next_nonnote_insn (insn))

    if (BLOCK_FOR_INSN (insn))

      return BLOCK_FOR_INSN (insn)->index;

  return -1;

}

/* Similar to next_insn, but ignores insns in the delay slots of

   an annulled branch.  */

static rtx

next_insn_no_annul (rtx insn)

{

  if (insn)

    {

      /* If INSN is an annulled branch, skip any insns from the target

         of the branch.  */

      if (JUMP_P (insn)

          && INSN_ANNULLED_BRANCH_P (insn)

          && NEXT_INSN (PREV_INSN (insn)) != insn)

        {

          rtx next = NEXT_INSN (insn);

          enum rtx_code code = GET_CODE (next);

          while ((code == INSN || code == JUMP_INSN || code == CALL_INSN)

                 && INSN_FROM_TARGET_P (next))

            {

              insn = next;

              next = NEXT_INSN (insn);

              code = GET_CODE (next);

            }

        }

      insn = NEXT_INSN (insn);

      if (insn && NONJUMP_INSN_P (insn)

          && GET_CODE (PATTERN (insn)) == SEQUENCE)

        insn = XVECEXP (PATTERN (insn), 0, 0);

    }

  return insn;

}

/* Given X, some rtl, and RES, a pointer to a `struct resource', mark

   which resources are referenced by the insn.  If INCLUDE_DELAYED_EFFECTS

   is TRUE, resources used by the called routine will be included for

   CALL_INSNs.  */

void

mark_referenced_resources (rtx x, struct resources *res,

                           bool include_delayed_effects)

{

  enum rtx_code code = GET_CODE (x);

  int i, j;

  unsigned int r;

  const char *format_ptr;

  /* Handle leaf items for which we set resource flags.  Also, special-case

     CALL, SET and CLOBBER operators.  */

  switch (code)

    {

    case CONST:

    case CONST_INT:

    case CONST_DOUBLE:

    case CONST_FIXED:

    case CONST_VECTOR:

    case PC:

    case SYMBOL_REF:

    case LABEL_REF:

      return;

    case SUBREG:

      if (!REG_P (SUBREG_REG (x)))

        mark_referenced_resources (SUBREG_REG (x), res, false);

      else

        {

          unsigned int regno = subreg_regno (x);

          unsigned int last_regno = regno + subreg_nregs (x);

          gcc_assert (last_regno <= FIRST_PSEUDO_REGISTER);

          for (r = regno; r < last_regno; r++)

            SET_HARD_REG_BIT (res->regs, r);

        }

      return;

    case REG:

      gcc_assert (HARD_REGISTER_P (x));

      add_to_hard_reg_set (&res->regs, GET_MODE (x), REGNO (x));

      return;

    case MEM:

      /* If this memory shouldn't change, it really isn't referencing

         memory.  */

      if (MEM_READONLY_P (x))

        res->unch_memory = 1;

      else

        res->memory = 1;

      res->volatil |= MEM_VOLATILE_P (x);

      /* Mark registers used to access memory.  */

      mark_referenced_resources (XEXP (x, 0), res, false);

      return;

    case CC0:

      res->cc = 1;

      return;

    case UNSPEC_VOLATILE:

    case TRAP_IF:

    case ASM_INPUT:

      /* Traditional asm's are always volatile.  */

      res->volatil = 1;

      break;

    case ASM_OPERANDS:

      res->volatil |= MEM_VOLATILE_P (x);

      /* For all ASM_OPERANDS, we must traverse the vector of input operands.

         We can not just fall through here since then we would be confused

         by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate

         traditional asms unlike their normal usage.  */

      for (i = 0; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)

        mark_referenced_resources (ASM_OPERANDS_INPUT (x, i), res, false);

      return;

    case CALL:

      /* The first operand will be a (MEM (xxx)) but doesn't really reference

         memory.  The second operand may be referenced, though.  */

      mark_referenced_resources (XEXP (XEXP (x, 0), 0), res, false);

      mark_referenced_resources (XEXP (x, 1), res, false);

      return;

    case SET:

      /* Usually, the first operand of SET is set, not referenced.  But

         registers used to access memory are referenced.  SET_DEST is

         also referenced if it is a ZERO_EXTRACT.  */

      mark_referenced_resources (SET_SRC (x), res, false);

      x = SET_DEST (x);

      if (GET_CODE (x) == ZERO_EXTRACT

          || GET_CODE (x) == STRICT_LOW_PART)

        mark_referenced_resources (x, res, false);

      else if (GET_CODE (x) == SUBREG)

        x = SUBREG_REG (x);

      if (MEM_P (x))

        mark_referenced_resources (XEXP (x, 0), res, false);

      return;

    case CLOBBER:

      return;

    case CALL_INSN:

      if (include_delayed_effects)

        {

          /* A CALL references memory, the frame pointer if it exists, the

             stack pointer, any global registers and any registers given in

             USE insns immediately in front of the CALL.

             However, we may have moved some of the parameter loading insns

             into the delay slot of this CALL.  If so, the USE's for them

             don't count and should be skipped.  */

          rtx insn = PREV_INSN (x);

          rtx sequence = 0;

          int seq_size = 0;

          int i;

          /* If we are part of a delay slot sequence, point at the SEQUENCE.  */

          if (NEXT_INSN (insn) != x)

            {

              sequence = PATTERN (NEXT_INSN (insn));

              seq_size = XVECLEN (sequence, 0);

              gcc_assert (GET_CODE (sequence) == SEQUENCE);

            }

          res->memory = 1;

          SET_HARD_REG_BIT (res->regs, STACK_POINTER_REGNUM);

          if (frame_pointer_needed)

            {

              SET_HARD_REG_BIT (res->regs, FRAME_POINTER_REGNUM);

#if !HARD_FRAME_POINTER_IS_FRAME_POINTER

              SET_HARD_REG_BIT (res->regs, HARD_FRAME_POINTER_REGNUM);

#endif

            }

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

            if (global_regs[i])

              SET_HARD_REG_BIT (res->regs, i);

          /* Check for a REG_SETJMP.  If it exists, then we must

             assume that this call can need any register.

             This is done to be more conservative about how we handle setjmp.

             We assume that they both use and set all registers.  Using all

             registers ensures that a register will not be considered dead

             just because it crosses a setjmp call.  A register should be

             considered dead only if the setjmp call returns nonzero.  */

          if (find_reg_note (x, REG_SETJMP, NULL))

            SET_HARD_REG_SET (res->regs);

          {

            rtx link;

            for (link = CALL_INSN_FUNCTION_USAGE (x);

                 link;

                 link = XEXP (link, 1))

              if (GET_CODE (XEXP (link, 0)) == USE)

                {

                  for (i = 1; i < seq_size; i++)

                    {

                      rtx slot_pat = PATTERN (XVECEXP (sequence, 0, i));

                      if (GET_CODE (slot_pat) == SET

                          && rtx_equal_p (SET_DEST (slot_pat),

                                          XEXP (XEXP (link, 0), 0)))

                        break;

                    }

                  if (i >= seq_size)

                    mark_referenced_resources (XEXP (XEXP (link, 0), 0),

                                               res, false);

                }

          }

        }

      /* ... fall through to other INSN processing ...  */

    case INSN:

    case JUMP_INSN:

#ifdef INSN_REFERENCES_ARE_DELAYED

      if (! include_delayed_effects

          && INSN_REFERENCES_ARE_DELAYED (x))

        return;

#endif

      /* No special processing, just speed up.  */

      mark_referenced_resources (PATTERN (x), res, include_delayed_effects);

      return;

    default:

      break;

    }

  /* Process each sub-expression and flag what it needs.  */

  format_ptr = GET_RTX_FORMAT (code);

  for (i = 0; i < GET_RTX_LENGTH (code); i++)

    switch (*format_ptr++)

      {

      case 'e':

        mark_referenced_resources (XEXP (x, i), res, include_delayed_effects);

        break;

      case 'E':

        for (j = 0; j < XVECLEN (x, i); j++)

          mark_referenced_resources (XVECEXP (x, i, j), res,

                                     include_delayed_effects);

        break;

      }

}

/* A subroutine of mark_target_live_regs.  Search forward from TARGET

   looking for registers that are set before they are used.  These are dead.

   Stop after passing a few conditional jumps, and/or a small

   number of unconditional branches.  */

static rtx

find_dead_or_set_registers (rtx target, struct resources *res,

                            rtx *jump_target, int jump_count,

                            struct resources set, struct resources needed)

{

  HARD_REG_SET scratch;

  rtx insn, next;

  rtx jump_insn = 0;

  int i;

  for (insn = target; insn; insn = next)

    {

      rtx this_jump_insn = insn;

      next = NEXT_INSN (insn);

      /* If this instruction can throw an exception, then we don't

         know where we might end up next.  That means that we have to

         assume that whatever we have already marked as live really is

         live.  */

      if (can_throw_internal (insn))

        break;

      switch (GET_CODE (insn))

        {

        case CODE_LABEL:

          /* After a label, any pending dead registers that weren't yet

             used can be made dead.  */

          AND_COMPL_HARD_REG_SET (pending_dead_regs, needed.regs);

          AND_COMPL_HARD_REG_SET (res->regs, pending_dead_regs);

          CLEAR_HARD_REG_SET (pending_dead_regs);

          continue;

        case BARRIER:

        case NOTE:

          continue;

        case INSN:

          if (GET_CODE (PATTERN (insn)) == USE)

            {

              /* If INSN is a USE made by update_block, we care about the

                 underlying insn.  Any registers set by the underlying insn

                 are live since the insn is being done somewhere else.  */

              if (INSN_P (XEXP (PATTERN (insn), 0)))

                mark_set_resources (XEXP (PATTERN (insn), 0), res, 0,

                                    MARK_SRC_DEST_CALL);

              /* All other USE insns are to be ignored.  */

              continue;

            }

          else if (GET_CODE (PATTERN (insn)) == CLOBBER)

            continue;

          else if (GET_CODE (PATTERN (insn)) == SEQUENCE)

            {

              /* An unconditional jump can be used to fill the delay slot

                 of a call, so search for a JUMP_INSN in any position.  */

              for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)

                {

                  this_jump_insn = XVECEXP (PATTERN (insn), 0, i);

                  if (JUMP_P (this_jump_insn))

                    break;

                }

            }

        default:

          break;

        }

      if (JUMP_P (this_jump_insn))

        {

          if (jump_count++ < 10)

            {

              if (any_uncondjump_p (this_jump_insn)

                  || ANY_RETURN_P (PATTERN (this_jump_insn)))

                {

                  next = JUMP_LABEL (this_jump_insn);

                  if (ANY_RETURN_P (next))

                    next = NULL_RTX;

                  if (jump_insn == 0)

                    {

                      jump_insn = insn;

                      if (jump_target)

                        *jump_target = JUMP_LABEL (this_jump_insn);

                    }

                }

              else if (any_condjump_p (this_jump_insn))

                {

                  struct resources target_set, target_res;

                  struct resources fallthrough_res;

                  /* We can handle conditional branches here by following

                     both paths, and then IOR the results of the two paths

                     together, which will give us registers that are dead

                     on both paths.  Since this is expensive, we give it

                     a much higher cost than unconditional branches.  The

                     cost was chosen so that we will follow at most 1

                     conditional branch.  */

                  jump_count += 4;

                  if (jump_count >= 10)

                    break;

                  mark_referenced_resources (insn, &needed, true);

                  /* For an annulled branch, mark_set_resources ignores slots

                     filled by instructions from the target.  This is correct

                     if the branch is not taken.  Since we are following both

                     paths from the branch, we must also compute correct info

                     if the branch is taken.  We do this by inverting all of

                     the INSN_FROM_TARGET_P bits, calling mark_set_resources,

                     and then inverting the INSN_FROM_TARGET_P bits again.  */

                  if (GET_CODE (PATTERN (insn)) == SEQUENCE

                      && INSN_ANNULLED_BRANCH_P (this_jump_insn))

                    {

                      for (i = 1; i < XVECLEN (PATTERN (insn), 0); i++)

                        INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i))

                          = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i));

                      target_set = set;

                      mark_set_resources (insn, &target_set, 0,

                                          MARK_SRC_DEST_CALL);

                      for (i = 1; i < XVECLEN (PATTERN (insn), 0); i++)

                        INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i))

                          = ! INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i));

                      mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);

                    }

                  else

                    {

                      mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);

                      target_set = set;

                    }

                  target_res = *res;

                  COPY_HARD_REG_SET (scratch, target_set.regs);

                  AND_COMPL_HARD_REG_SET (scratch, needed.regs);

                  AND_COMPL_HARD_REG_SET (target_res.regs, scratch);

                  fallthrough_res = *res;

                  COPY_HARD_REG_SET (scratch, set.regs);

                  AND_COMPL_HARD_REG_SET (scratch, needed.regs);

                  AND_COMPL_HARD_REG_SET (fallthrough_res.regs, scratch);

                  if (!ANY_RETURN_P (JUMP_LABEL (this_jump_insn)))

                    find_dead_or_set_registers (JUMP_LABEL (this_jump_insn),

                                                &target_res, 0, jump_count,

                                                target_set, needed);

                  find_dead_or_set_registers (next,

                                              &fallthrough_res, 0, jump_count,

                                              set, needed);

                  IOR_HARD_REG_SET (fallthrough_res.regs, target_res.regs);

                  AND_HARD_REG_SET (res->regs, fallthrough_res.regs);

                  break;

                }

              else

                break;

            }

          else

            {

              /* Don't try this optimization if we expired our jump count

                 above, since that would mean there may be an infinite loop

                 in the function being compiled.  */

              jump_insn = 0;

              break;

            }

        }

      mark_referenced_resources (insn, &needed, true);

      mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL);

      COPY_HARD_REG_SET (scratch, set.regs);

      AND_COMPL_HARD_REG_SET (scratch, needed.regs);

      AND_COMPL_HARD_REG_SET (res->regs, scratch);

    }

  return jump_insn;

}

/* Given X, a part of an insn, and a pointer to a `struct resource',

   RES, indicate which resources are modified by the insn. If

   MARK_TYPE is MARK_SRC_DEST_CALL, also mark resources potentially

   set by the called routine.

   If IN_DEST is nonzero, it means we are inside a SET.  Otherwise,

   objects are being referenced instead of set.

   We never mark the insn as modifying the condition code unless it explicitly

   SETs CC0 even though this is not totally correct.  The reason for this is

   that we require a SET of CC0 to immediately precede the reference to CC0.

   So if some other insn sets CC0 as a side-effect, we know it cannot affect

   our computation and thus may be placed in a delay slot.  */

void

mark_set_resources (rtx x, struct resources *res, int in_dest,

                    enum mark_resource_type mark_type)

{

  enum rtx_code code;

  int i, j;

  unsigned int r;

  const char *format_ptr;

 restart:

  code = GET_CODE (x);

  switch (code)

    {

    case NOTE:

    case BARRIER:

    case CODE_LABEL:

    case USE:

    case CONST_INT:

    case CONST_DOUBLE:

    case CONST_FIXED:

    case CONST_VECTOR:

    case LABEL_REF:

    case SYMBOL_REF:

    case CONST:

    case PC:

      /* These don't set any resources.  */

      return;

    case CC0:

      if (in_dest)

        res->cc = 1;

      return;

    case CALL_INSN:

      /* Called routine modifies the condition code, memory, any registers

         that aren't saved across calls, global registers and anything

         explicitly CLOBBERed immediately after the CALL_INSN.  */

      if (mark_type == MARK_SRC_DEST_CALL)

        {

          rtx link;

          res->cc = res->memory = 1;

          IOR_HARD_REG_SET (res->regs, regs_invalidated_by_call);

          for (link = CALL_INSN_FUNCTION_USAGE (x);

               link; link = XEXP (link, 1))

            if (GET_CODE (XEXP (link, 0)) == CLOBBER)

              mark_set_resources (SET_DEST (XEXP (link, 0)), res, 1,

                                  MARK_SRC_DEST);

          /* Check for a REG_SETJMP.  If it exists, then we must

             assume that this call can clobber any register.  */

          if (find_reg_note (x, REG_SETJMP, NULL))

            SET_HARD_REG_SET (res->regs);

        }

      /* ... and also what its RTL says it modifies, if anything.  */

    case JUMP_INSN:

    case INSN:

        /* An insn consisting of just a CLOBBER (or USE) is just for flow

           and doesn't actually do anything, so we ignore it.  */

#ifdef INSN_SETS_ARE_DELAYED

      if (mark_type != MARK_SRC_DEST_CALL

          && INSN_SETS_ARE_DELAYED (x))

        return;

#endif

      x = PATTERN (x);

      if (GET_CODE (x) != USE && GET_CODE (x) != CLOBBER)

        goto restart;

      return;

    case SET:

      /* If the source of a SET is a CALL, this is actually done by

         the called routine.  So only include it if we are to include the

         effects of the calling routine.  */

      mark_set_resources (SET_DEST (x), res,

                          (mark_type == MARK_SRC_DEST_CALL

                           || GET_CODE (SET_SRC (x)) != CALL),

                          mark_type);