/* Shared code for before and after reload gcse implementations.
   Copyright (C) 1997-2025 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/>.

   It is expected that more hunks of gcse.cc and postreload-gcse.cc should
   migrate into this file.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "rtl.h"
#include "df.h"
#include "gcse-common.h"
#include "regs.h"
#include "function-abi.h"

/* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
   Note we store a pair of elements in the list, so they have to be
   taken off pairwise.  */

void
canon_list_insert (rtx dest, const_rtx x ATTRIBUTE_UNUSED, void *data)
{
  rtx dest_addr;
  int bb;
  modify_pair pair;

  while (GET_CODE (dest) == SUBREG
      || GET_CODE (dest) == ZERO_EXTRACT
      || GET_CODE (dest) == STRICT_LOW_PART)
    dest = XEXP (dest, 0);

  /* If DEST is not a MEM, then it will not conflict with a load.  Note
     that function calls are assumed to clobber memory, but are handled
     elsewhere.  */

  if (! MEM_P (dest))
    return;

  dest_addr = get_addr (XEXP (dest, 0));
  dest_addr = canon_rtx (dest_addr);
  rtx_insn *insn = ((struct gcse_note_stores_info *)data)->insn;
  bb = BLOCK_FOR_INSN (insn)->index;

  pair.dest = dest;
  pair.dest_addr = dest_addr;
  vec<modify_pair> *canon_mem_list
    = ((struct gcse_note_stores_info *)data)->canon_mem_list;
  canon_mem_list[bb].safe_push (pair);
}

/* Record memory modification information for INSN.  We do not actually care
   about the memory location(s) that are set, or even how they are set (consider
   a CALL_INSN).  We merely need to record which insns modify memory.  */

void
record_last_mem_set_info_common (rtx_insn *insn,
				 vec<rtx_insn *> *modify_mem_list,
				 vec<modify_pair> *canon_modify_mem_list,
				 bitmap modify_mem_list_set,
				 bitmap blocks_with_calls)

{
  int bb;

  bb = BLOCK_FOR_INSN (insn)->index;
  modify_mem_list[bb].safe_push (insn);
  bitmap_set_bit (modify_mem_list_set, bb);

  if (CALL_P (insn))
    bitmap_set_bit (blocks_with_calls, bb);
  else
    {
      struct gcse_note_stores_info data;
      data.insn = insn;
      data.canon_mem_list = canon_modify_mem_list;
      note_stores (insn, canon_list_insert, (void*) &data);
    }
}


/* For each block, compute whether X is transparent.  X is either an
   expression or an assignment [though we don't care which, for this context
   an assignment is treated as an expression].  For each block where an
   element of X is modified, reset the INDX bit in BMAP.

   BLOCKS_WITH_CALLS indicates which blocks contain CALL_INSNs which kill
   memory.

   MODIFY_MEM_LIST_SET indicates which blocks have memory stores which might
   kill a particular memory location.

   CANON_MODIFY_MEM_LIST is the canonicalized list of memory locations modified
   for each block.  */

void
compute_transp (const_rtx x, int indx, sbitmap *bmap,
		bitmap blocks_with_calls,
		bitmap modify_mem_list_set,
	        vec<modify_pair> *canon_modify_mem_list)
{
  int i, j;
  enum rtx_code code;
  const char *fmt;

  /* repeat is used to turn tail-recursion into iteration since GCC
     can't do it when there's no return value.  */
 repeat:

  if (x == 0)
    return;

  code = GET_CODE (x);
  switch (code)
    {
    case REG:
      {
	df_ref def;
	for (def = DF_REG_DEF_CHAIN (REGNO (x));
	     def;
	     def = DF_REF_NEXT_REG (def))
	  bitmap_clear_bit (bmap[DF_REF_BB (def)->index], indx);

	/* Check for hard registers that are partially clobbered (but not
	   fully clobbered) by calls.  Such partial clobbers do not have
	   an associated definition or use in the DF representation,
	   but they do prevent the register from being transparent.

	   ??? The check here is fairly crude.  We could instead maintain
	   separate blocks_with_calls bitmaps for each ABI.  */
	if (HARD_REGISTER_P (x))
	  for (unsigned int i = 0; i < NUM_ABI_IDS; ++i)
	    {
	      const predefined_function_abi &abi = function_abis[i];
	      if (abi.initialized_p ()
		  && overlaps_hard_reg_set_p (abi.only_partial_reg_clobbers (),
					      GET_MODE (x), REGNO (x)))
		{
		  bitmap_iterator bi;
		  unsigned bb_index;
		  EXECUTE_IF_SET_IN_BITMAP (blocks_with_calls, 0, bb_index, bi)
		    bitmap_clear_bit (bmap[bb_index], indx);
		  break;
		}
	    }
      }

      return;

    case MEM:
      if (! MEM_READONLY_P (x))
	{
	  bitmap_iterator bi;
	  unsigned bb_index;
	  rtx x_addr;

	  x_addr = get_addr (XEXP (x, 0));
	  x_addr = canon_rtx (x_addr);

	  /* First handle all the blocks with calls.  We don't need to
	     do any list walking for them.  */
	  EXECUTE_IF_SET_IN_BITMAP (blocks_with_calls, 0, bb_index, bi)
	    {
	      bitmap_clear_bit (bmap[bb_index], indx);
	    }

	  /* Now iterate over the blocks which have memory modifications
	     but which do not have any calls.  */
	  EXECUTE_IF_AND_COMPL_IN_BITMAP (modify_mem_list_set,
					  blocks_with_calls,
					  0, bb_index, bi)
	    {
	      vec<modify_pair> list
		= canon_modify_mem_list[bb_index];
	      modify_pair *pair;
	      unsigned ix;

	      FOR_EACH_VEC_ELT_REVERSE (list, ix, pair)
		{
		  rtx dest = pair->dest;
		  rtx dest_addr = pair->dest_addr;

		  if (canon_true_dependence (dest, GET_MODE (dest),
					     dest_addr, x, x_addr))
		    {
		      bitmap_clear_bit (bmap[bb_index], indx);
		      break;
		    }
	        }
	    }
	}

      x = XEXP (x, 0);
      goto repeat;

    case PC:
    case CONST:
    CASE_CONST_ANY:
    case SYMBOL_REF:
    case LABEL_REF:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
      return;

    default:
      break;
    }

  for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
    {
      if (fmt[i] == 'e')
	{
	  /* If we are about to do the last recursive call
	     needed at this level, change it into iteration.
	     This function is called enough to be worth it.  */
	  if (i == 0)
	    {
	      x = XEXP (x, i);
	      goto repeat;
	    }

	  compute_transp (XEXP (x, i), indx, bmap, blocks_with_calls,
			  modify_mem_list_set, canon_modify_mem_list);
	}
      else if (fmt[i] == 'E')
	for (j = 0; j < XVECLEN (x, i); j++)
	  compute_transp (XVECEXP (x, i, j), indx, bmap, blocks_with_calls,
			  modify_mem_list_set, canon_modify_mem_list);
    }
}