unroll.c

GUN开源阻止下的编译器GCC

static void
final_reg_note_copy (notes, map)
     rtx notes;
     struct inline_remap *map;
{
  rtx note;

  for (note = notes; note; note = XEXP (note, 1))
    if (GET_CODE (note) == INSN_LIST)
      XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
}

/* Copy each instruction in the loop, substituting from map as appropriate.
   This is very similar to a loop in expand_inline_function.  */
  
static void
copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
		unroll_type, start_label, loop_end, insert_before,
		copy_notes_from)
     rtx copy_start, copy_end;
     struct inline_remap *map;
     rtx exit_label;
     int last_iteration;
     enum unroll_types unroll_type;
     rtx start_label, loop_end, insert_before, copy_notes_from;
{
  rtx insn, pattern;
  rtx tem, copy;
  int dest_reg_was_split, i;
  rtx cc0_insn = 0;
  rtx final_label = 0;
  rtx giv_inc, giv_dest_reg, giv_src_reg;

  /* If this isn't the last iteration, then map any references to the
     start_label to final_label.  Final label will then be emitted immediately
     after the end of this loop body if it was ever used.

     If this is the last iteration, then map references to the start_label
     to itself.  */
  if (! last_iteration)
    {
      final_label = gen_label_rtx ();
      map->label_map[CODE_LABEL_NUMBER (start_label)] = final_label;
    }
  else
    map->label_map[CODE_LABEL_NUMBER (start_label)] = start_label;

  start_sequence ();
  
  insn = copy_start;
  do
    {
      insn = NEXT_INSN (insn);
      
      map->orig_asm_operands_vector = 0;
      
      switch (GET_CODE (insn))
	{
	case INSN:
	  pattern = PATTERN (insn);
	  copy = 0;
	  giv_inc = 0;
	  
	  /* Check to see if this is a giv that has been combined with
	     some split address givs.  (Combined in the sense that 
	     `combine_givs' in loop.c has put two givs in the same register.)
	     In this case, we must search all givs based on the same biv to
	     find the address givs.  Then split the address givs.
	     Do this before splitting the giv, since that may map the
	     SET_DEST to a new register.  */
	  
	  if (GET_CODE (pattern) == SET
	      && GET_CODE (SET_DEST (pattern)) == REG
	      && addr_combined_regs[REGNO (SET_DEST (pattern))])
	    {
	      struct iv_class *bl;
	      struct induction *v, *tv;
	      int regno = REGNO (SET_DEST (pattern));
	      
	      v = addr_combined_regs[REGNO (SET_DEST (pattern))];
	      bl = reg_biv_class[REGNO (v->src_reg)];
	      
	      /* Although the giv_inc amount is not needed here, we must call
		 calculate_giv_inc here since it might try to delete the
		 last insn emitted.  If we wait until later to call it,
		 we might accidentally delete insns generated immediately
		 below by emit_unrolled_add.  */

	      giv_inc = calculate_giv_inc (pattern, insn, regno);

	      /* Now find all address giv's that were combined with this
		 giv 'v'.  */
	      for (tv = bl->giv; tv; tv = tv->next_iv)
		if (tv->giv_type == DEST_ADDR && tv->same == v)
		  {
		    int this_giv_inc = INTVAL (giv_inc);

		    /* Scale this_giv_inc if the multiplicative factors of
		       the two givs are different.  */
		    if (tv->mult_val != v->mult_val)
		      this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
				      * INTVAL (tv->mult_val));
		       
		    tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
		    *tv->location = tv->dest_reg;
		    
		    if (last_iteration && unroll_type != UNROLL_COMPLETELY)
		      {
			/* Must emit an insn to increment the split address
			   giv.  Add in the const_adjust field in case there
			   was a constant eliminated from the address.  */
			rtx value, dest_reg;
			
			/* tv->dest_reg will be either a bare register,
			   or else a register plus a constant.  */
			if (GET_CODE (tv->dest_reg) == REG)
			  dest_reg = tv->dest_reg;
			else
			  dest_reg = XEXP (tv->dest_reg, 0);
			
			/* Check for shared address givs, and avoid
			   incrementing the shared pseudo reg more than
			   once.  */
			if (! tv->same_insn)
			  {
			    /* tv->dest_reg may actually be a (PLUS (REG)
			       (CONST)) here, so we must call plus_constant
			       to add the const_adjust amount before calling
			       emit_unrolled_add below.  */
			    value = plus_constant (tv->dest_reg,
						   tv->const_adjust);

			    /* The constant could be too large for an add
			       immediate, so can't directly emit an insn
			       here.  */
			    emit_unrolled_add (dest_reg, XEXP (value, 0),
					       XEXP (value, 1));
			  }
			
			/* Reset the giv to be just the register again, in case
			   it is used after the set we have just emitted.
			   We must subtract the const_adjust factor added in
			   above.  */
			tv->dest_reg = plus_constant (dest_reg,
						      - tv->const_adjust);
			*tv->location = tv->dest_reg;
		      }
		  }
	    }
	  
	  /* If this is a setting of a splittable variable, then determine
	     how to split the variable, create a new set based on this split,
	     and set up the reg_map so that later uses of the variable will
	     use the new split variable.  */
	  
	  dest_reg_was_split = 0;
	  
	  if (GET_CODE (pattern) == SET
	      && GET_CODE (SET_DEST (pattern)) == REG
	      && splittable_regs[REGNO (SET_DEST (pattern))])
	    {
	      int regno = REGNO (SET_DEST (pattern));
	      
	      dest_reg_was_split = 1;
	      
	      /* Compute the increment value for the giv, if it wasn't
		 already computed above.  */

	      if (giv_inc == 0)
		giv_inc = calculate_giv_inc (pattern, insn, regno);
	      giv_dest_reg = SET_DEST (pattern);
	      giv_src_reg = SET_DEST (pattern);

	      if (unroll_type == UNROLL_COMPLETELY)
		{
		  /* Completely unrolling the loop.  Set the induction
		     variable to a known constant value.  */
		  
		  /* The value in splittable_regs may be an invariant
		     value, so we must use plus_constant here.  */
		  splittable_regs[regno]
		    = plus_constant (splittable_regs[regno], INTVAL (giv_inc));

		  if (GET_CODE (splittable_regs[regno]) == PLUS)
		    {
		      giv_src_reg = XEXP (splittable_regs[regno], 0);
		      giv_inc = XEXP (splittable_regs[regno], 1);
		    }
		  else
		    {
		      /* The splittable_regs value must be a REG or a
			 CONST_INT, so put the entire value in the giv_src_reg
			 variable.  */
		      giv_src_reg = splittable_regs[regno];
		      giv_inc = const0_rtx;
		    }
		}
	      else
		{
		  /* Partially unrolling loop.  Create a new pseudo
		     register for the iteration variable, and set it to
		     be a constant plus the original register.  Except
		     on the last iteration, when the result has to
		     go back into the original iteration var register.  */
		  
		  /* Handle bivs which must be mapped to a new register
		     when split.  This happens for bivs which need their
		     final value set before loop entry.  The new register
		     for the biv was stored in the biv's first struct
		     induction entry by find_splittable_regs.  */

		  if (regno < max_reg_before_loop
		      && reg_iv_type[regno] == BASIC_INDUCT)
		    {
		      giv_src_reg = reg_biv_class[regno]->biv->src_reg;
		      giv_dest_reg = giv_src_reg;
		    }
		  
#if 0
		  /* If non-reduced/final-value givs were split, then
		     this would have to remap those givs also.  See
		     find_splittable_regs.  */
#endif
		  
		  splittable_regs[regno]
		    = GEN_INT (INTVAL (giv_inc)
			       + INTVAL (splittable_regs[regno]));
		  giv_inc = splittable_regs[regno];
		  
		  /* Now split the induction variable by changing the dest
		     of this insn to a new register, and setting its
		     reg_map entry to point to this new register.

		     If this is the last iteration, and this is the last insn
		     that will update the iv, then reuse the original dest,
		     to ensure that the iv will have the proper value when
		     the loop exits or repeats.

		     Using splittable_regs_updates here like this is safe,
		     because it can only be greater than one if all
		     instructions modifying the iv are always executed in
		     order.  */

		  if (! last_iteration
		      || (splittable_regs_updates[regno]-- != 1))
		    {
		      tem = gen_reg_rtx (GET_MODE (giv_src_reg));
		      giv_dest_reg = tem;
		      map->reg_map[regno] = tem;
		    }
		  else
		    map->reg_map[regno] = giv_src_reg;
		}

	      /* The constant being added could be too large for an add
		 immediate, so can't directly emit an insn here.  */
	      emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
	      copy = get_last_insn ();
	      pattern = PATTERN (copy);
	    }
	  else
	    {
	      pattern = copy_rtx_and_substitute (pattern, map);
	      copy = emit_insn (pattern);
	    }
	  REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
	  
#ifdef HAVE_cc0
	  /* If this insn is setting CC0, it may need to look at
	     the insn that uses CC0 to see what type of insn it is.
	     In that case, the call to recog via validate_change will
	     fail.  So don't substitute constants here.  Instead,
	     do it when we emit the following insn.

	     For example, see the pyr.md file.  That machine has signed and
	     unsigned compares.  The compare patterns must check the
	     following branch insn to see which what kind of compare to
	     emit.

	     If the previous insn set CC0, substitute constants on it as
	     well.  */
	  if (sets_cc0_p (PATTERN (copy)) != 0)
	    cc0_insn = copy;
	  else
	    {
	      if (cc0_insn)
		try_constants (cc0_insn, map);
	      cc0_insn = 0;
	      try_constants (copy, map);
	    }
#else
	  try_constants (copy, map);
#endif

	  /* Make split induction variable constants `permanent' since we
	     know there are no backward branches across iteration variable
	     settings which would invalidate this.  */
	  if (dest_reg_was_split)
	    {
	      int regno = REGNO (SET_DEST (pattern));

	      if (regno < map->const_equiv_map_size
		  && map->const_age_map[regno] == map->const_age)
		map->const_age_map[regno] = -1;
	    }
	  break;
	  
	case JUMP_INSN:
	  pattern = copy_rtx_and_substitute (PATTERN (insn), map);
	  copy = emit_jump_insn (pattern);
	  REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);

	  if (JUMP_LABEL (insn) == start_label && insn == copy_end
	      && ! last_iteration)
	    {
	      /* This is a branch to the beginning of the loop; this is the
		 last insn being copied; and this is not the last iteration.
		 In this case, we want to change the original fall through
		 case to be a branch past the end of the loop, and the
		 original jump label case to fall_through.  */

	      if (invert_exp (pattern, copy))
		{
		  if (! redirect_exp (&pattern,
				      map->label_map[CODE_LABEL_NUMBER
						     (JUMP_LABEL (insn))],
				      exit_label, copy))
		    abort ();
		}
	      else
		{
		  rtx jmp;
		  rtx lab = gen_label_rtx ();
		  /* Can't do it by reversing the jump (probably because we
		     couldn't reverse the conditions), so emit a new
		     jump_insn after COPY, and redirect the jump around
		     that.  */
		  jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
		  jmp = emit_barrier_after (jmp);
		  emit_label_after (lab, jmp);
		  LABEL_NUSES (lab) = 0;
		  if (! redirect_exp (&pattern,
				      map->label_map[CODE_LABEL_NUMBER
						     (JUMP_LABEL (insn))],
				      lab, copy))
		    abort ();
		}
	    }
	  
#ifdef HAVE_cc0
	  if (cc0_insn)
	    try_constants (cc0_insn, map);
	  cc0_insn = 0;
#endif
	  try_constants (copy, map);

	  /* Set the jump label of COPY correctly to avoid problems with
	     later passes of unroll_loop, if INSN had jump label set.  */
	  if (JUMP_LABEL (insn))
	    {
	      rtx label = 0;

	      /* Can't use the label_map for every insn, since this may be
		 the backward branch, and hence the label was not mapped.  */
	      if (GET_CODE (pattern) == SET)
		{
		  tem = SET_SRC (pattern);
		  if (GET_CODE (tem) == LABEL_REF)
		    label = XEXP (tem, 0);
		  else if (GET_CODE (tem) == IF_THEN_ELSE)
		    {
		      if (XEXP (tem, 1) != pc_rtx)
			label = XEXP (XEXP (tem, 1), 0);