1378 lines
35 KiB
C
1378 lines
35 KiB
C
/* Common subexpression elimination library for GNU compiler.
|
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Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
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1999, 2000, 2001 Free Software Foundation, Inc.
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This file is part of GCC.
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|
||
GCC is free software; you can redistribute it and/or modify it under
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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.
|
||
|
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
|
||
WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
||
for more details.
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||
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You should have received a copy of the GNU General Public License
|
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along with GCC; see the file COPYING. If not, write to the Free
|
||
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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#include "config.h"
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#include "system.h"
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#include "rtl.h"
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#include "tm_p.h"
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#include "regs.h"
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#include "hard-reg-set.h"
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#include "flags.h"
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#include "real.h"
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#include "insn-config.h"
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#include "recog.h"
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#include "function.h"
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#include "expr.h"
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#include "toplev.h"
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#include "output.h"
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#include "ggc.h"
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#include "obstack.h"
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#include "hashtab.h"
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#include "cselib.h"
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static int entry_and_rtx_equal_p PARAMS ((const void *, const void *));
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static unsigned int get_value_hash PARAMS ((const void *));
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static struct elt_list *new_elt_list PARAMS ((struct elt_list *,
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cselib_val *));
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static struct elt_loc_list *new_elt_loc_list PARAMS ((struct elt_loc_list *,
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rtx));
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static void unchain_one_value PARAMS ((cselib_val *));
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static void unchain_one_elt_list PARAMS ((struct elt_list **));
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static void unchain_one_elt_loc_list PARAMS ((struct elt_loc_list **));
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static void clear_table PARAMS ((int));
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static int discard_useless_locs PARAMS ((void **, void *));
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static int discard_useless_values PARAMS ((void **, void *));
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static void remove_useless_values PARAMS ((void));
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static rtx wrap_constant PARAMS ((enum machine_mode, rtx));
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static unsigned int hash_rtx PARAMS ((rtx, enum machine_mode, int));
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static cselib_val *new_cselib_val PARAMS ((unsigned int,
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enum machine_mode));
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static void add_mem_for_addr PARAMS ((cselib_val *, cselib_val *,
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rtx));
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static cselib_val *cselib_lookup_mem PARAMS ((rtx, int));
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static void cselib_invalidate_regno PARAMS ((unsigned int,
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enum machine_mode));
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static int cselib_mem_conflict_p PARAMS ((rtx, rtx));
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static int cselib_invalidate_mem_1 PARAMS ((void **, void *));
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static void cselib_invalidate_mem PARAMS ((rtx));
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static void cselib_invalidate_rtx PARAMS ((rtx, rtx, void *));
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static void cselib_record_set PARAMS ((rtx, cselib_val *,
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cselib_val *));
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static void cselib_record_sets PARAMS ((rtx));
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/* There are three ways in which cselib can look up an rtx:
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- for a REG, the reg_values table (which is indexed by regno) is used
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- for a MEM, we recursively look up its address and then follow the
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addr_list of that value
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- for everything else, we compute a hash value and go through the hash
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table. Since different rtx's can still have the same hash value,
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this involves walking the table entries for a given value and comparing
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the locations of the entries with the rtx we are looking up. */
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/* A table that enables us to look up elts by their value. */
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static htab_t hash_table;
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/* This is a global so we don't have to pass this through every function.
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It is used in new_elt_loc_list to set SETTING_INSN. */
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static rtx cselib_current_insn;
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/* Every new unknown value gets a unique number. */
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static unsigned int next_unknown_value;
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/* The number of registers we had when the varrays were last resized. */
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static unsigned int cselib_nregs;
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/* Count values without known locations. Whenever this grows too big, we
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remove these useless values from the table. */
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static int n_useless_values;
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/* Number of useless values before we remove them from the hash table. */
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#define MAX_USELESS_VALUES 32
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/* This table maps from register number to values. It does not contain
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pointers to cselib_val structures, but rather elt_lists. The purpose is
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to be able to refer to the same register in different modes. */
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static varray_type reg_values;
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#define REG_VALUES(I) VARRAY_ELT_LIST (reg_values, (I))
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/* Here the set of indices I with REG_VALUES(I) != 0 is saved. This is used
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in clear_table() for fast emptying. */
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static varray_type used_regs;
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/* We pass this to cselib_invalidate_mem to invalidate all of
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memory for a non-const call instruction. */
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static rtx callmem;
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||
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/* Memory for our structures is allocated from this obstack. */
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static struct obstack cselib_obstack;
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||
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/* Used to quickly free all memory. */
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static char *cselib_startobj;
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/* Caches for unused structures. */
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static cselib_val *empty_vals;
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static struct elt_list *empty_elt_lists;
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static struct elt_loc_list *empty_elt_loc_lists;
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/* Set by discard_useless_locs if it deleted the last location of any
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value. */
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static int values_became_useless;
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/* Allocate a struct elt_list and fill in its two elements with the
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arguments. */
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static struct elt_list *
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new_elt_list (next, elt)
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struct elt_list *next;
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cselib_val *elt;
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{
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struct elt_list *el = empty_elt_lists;
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if (el)
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empty_elt_lists = el->next;
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else
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el = (struct elt_list *) obstack_alloc (&cselib_obstack,
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sizeof (struct elt_list));
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el->next = next;
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el->elt = elt;
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return el;
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}
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/* Allocate a struct elt_loc_list and fill in its two elements with the
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arguments. */
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static struct elt_loc_list *
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new_elt_loc_list (next, loc)
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struct elt_loc_list *next;
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rtx loc;
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{
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struct elt_loc_list *el = empty_elt_loc_lists;
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if (el)
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empty_elt_loc_lists = el->next;
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else
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el = (struct elt_loc_list *) obstack_alloc (&cselib_obstack,
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sizeof (struct elt_loc_list));
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el->next = next;
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el->loc = loc;
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el->setting_insn = cselib_current_insn;
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return el;
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}
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/* The elt_list at *PL is no longer needed. Unchain it and free its
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storage. */
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static void
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unchain_one_elt_list (pl)
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struct elt_list **pl;
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{
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struct elt_list *l = *pl;
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*pl = l->next;
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l->next = empty_elt_lists;
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empty_elt_lists = l;
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}
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/* Likewise for elt_loc_lists. */
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static void
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unchain_one_elt_loc_list (pl)
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struct elt_loc_list **pl;
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{
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||
struct elt_loc_list *l = *pl;
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*pl = l->next;
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l->next = empty_elt_loc_lists;
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empty_elt_loc_lists = l;
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}
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/* Likewise for cselib_vals. This also frees the addr_list associated with
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V. */
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static void
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unchain_one_value (v)
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cselib_val *v;
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{
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while (v->addr_list)
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unchain_one_elt_list (&v->addr_list);
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v->u.next_free = empty_vals;
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empty_vals = v;
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}
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/* Remove all entries from the hash table. Also used during
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initialization. If CLEAR_ALL isn't set, then only clear the entries
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which are known to have been used. */
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static void
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clear_table (clear_all)
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int clear_all;
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{
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unsigned int i;
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if (clear_all)
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for (i = 0; i < cselib_nregs; i++)
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REG_VALUES (i) = 0;
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else
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for (i = 0; i < VARRAY_ACTIVE_SIZE (used_regs); i++)
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REG_VALUES (VARRAY_UINT (used_regs, i)) = 0;
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VARRAY_POP_ALL (used_regs);
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htab_empty (hash_table);
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obstack_free (&cselib_obstack, cselib_startobj);
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empty_vals = 0;
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empty_elt_lists = 0;
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empty_elt_loc_lists = 0;
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n_useless_values = 0;
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next_unknown_value = 0;
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}
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/* The equality test for our hash table. The first argument ENTRY is a table
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element (i.e. a cselib_val), while the second arg X is an rtx. We know
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that all callers of htab_find_slot_with_hash will wrap CONST_INTs into a
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CONST of an appropriate mode. */
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static int
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entry_and_rtx_equal_p (entry, x_arg)
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const void *entry, *x_arg;
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{
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struct elt_loc_list *l;
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const cselib_val *v = (const cselib_val *) entry;
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rtx x = (rtx) x_arg;
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enum machine_mode mode = GET_MODE (x);
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if (GET_CODE (x) == CONST_INT
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|| (mode == VOIDmode && GET_CODE (x) == CONST_DOUBLE))
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abort ();
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if (mode != GET_MODE (v->u.val_rtx))
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return 0;
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/* Unwrap X if necessary. */
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if (GET_CODE (x) == CONST
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&& (GET_CODE (XEXP (x, 0)) == CONST_INT
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|| GET_CODE (XEXP (x, 0)) == CONST_DOUBLE))
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x = XEXP (x, 0);
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/* We don't guarantee that distinct rtx's have different hash values,
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so we need to do a comparison. */
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for (l = v->locs; l; l = l->next)
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if (rtx_equal_for_cselib_p (l->loc, x))
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return 1;
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return 0;
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}
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/* The hash function for our hash table. The value is always computed with
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hash_rtx when adding an element; this function just extracts the hash
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value from a cselib_val structure. */
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static unsigned int
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get_value_hash (entry)
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const void *entry;
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{
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const cselib_val *v = (const cselib_val *) entry;
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return v->value;
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}
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/* Return true if X contains a VALUE rtx. If ONLY_USELESS is set, we
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only return true for values which point to a cselib_val whose value
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element has been set to zero, which implies the cselib_val will be
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removed. */
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int
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references_value_p (x, only_useless)
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rtx x;
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int only_useless;
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{
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enum rtx_code code = GET_CODE (x);
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const char *fmt = GET_RTX_FORMAT (code);
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int i, j;
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if (GET_CODE (x) == VALUE
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&& (! only_useless || CSELIB_VAL_PTR (x)->locs == 0))
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return 1;
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for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
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{
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if (fmt[i] == 'e' && references_value_p (XEXP (x, i), only_useless))
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return 1;
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else if (fmt[i] == 'E')
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for (j = 0; j < XVECLEN (x, i); j++)
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if (references_value_p (XVECEXP (x, i, j), only_useless))
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return 1;
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}
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return 0;
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}
|
||
|
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/* For all locations found in X, delete locations that reference useless
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values (i.e. values without any location). Called through
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htab_traverse. */
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static int
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discard_useless_locs (x, info)
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void **x;
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||
void *info ATTRIBUTE_UNUSED;
|
||
{
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||
cselib_val *v = (cselib_val *)*x;
|
||
struct elt_loc_list **p = &v->locs;
|
||
int had_locs = v->locs != 0;
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||
|
||
while (*p)
|
||
{
|
||
if (references_value_p ((*p)->loc, 1))
|
||
unchain_one_elt_loc_list (p);
|
||
else
|
||
p = &(*p)->next;
|
||
}
|
||
|
||
if (had_locs && v->locs == 0)
|
||
{
|
||
n_useless_values++;
|
||
values_became_useless = 1;
|
||
}
|
||
return 1;
|
||
}
|
||
|
||
/* If X is a value with no locations, remove it from the hashtable. */
|
||
|
||
static int
|
||
discard_useless_values (x, info)
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void **x;
|
||
void *info ATTRIBUTE_UNUSED;
|
||
{
|
||
cselib_val *v = (cselib_val *)*x;
|
||
|
||
if (v->locs == 0)
|
||
{
|
||
htab_clear_slot (hash_table, x);
|
||
unchain_one_value (v);
|
||
n_useless_values--;
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Clean out useless values (i.e. those which no longer have locations
|
||
associated with them) from the hash table. */
|
||
|
||
static void
|
||
remove_useless_values ()
|
||
{
|
||
/* First pass: eliminate locations that reference the value. That in
|
||
turn can make more values useless. */
|
||
do
|
||
{
|
||
values_became_useless = 0;
|
||
htab_traverse (hash_table, discard_useless_locs, 0);
|
||
}
|
||
while (values_became_useless);
|
||
|
||
/* Second pass: actually remove the values. */
|
||
htab_traverse (hash_table, discard_useless_values, 0);
|
||
|
||
if (n_useless_values != 0)
|
||
abort ();
|
||
}
|
||
|
||
/* Return nonzero if we can prove that X and Y contain the same value, taking
|
||
our gathered information into account. */
|
||
|
||
int
|
||
rtx_equal_for_cselib_p (x, y)
|
||
rtx x, y;
|
||
{
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
int i;
|
||
|
||
if (GET_CODE (x) == REG || GET_CODE (x) == MEM)
|
||
{
|
||
cselib_val *e = cselib_lookup (x, GET_MODE (x), 0);
|
||
|
||
if (e)
|
||
x = e->u.val_rtx;
|
||
}
|
||
|
||
if (GET_CODE (y) == REG || GET_CODE (y) == MEM)
|
||
{
|
||
cselib_val *e = cselib_lookup (y, GET_MODE (y), 0);
|
||
|
||
if (e)
|
||
y = e->u.val_rtx;
|
||
}
|
||
|
||
if (x == y)
|
||
return 1;
|
||
|
||
if (GET_CODE (x) == VALUE && GET_CODE (y) == VALUE)
|
||
return CSELIB_VAL_PTR (x) == CSELIB_VAL_PTR (y);
|
||
|
||
if (GET_CODE (x) == VALUE)
|
||
{
|
||
cselib_val *e = CSELIB_VAL_PTR (x);
|
||
struct elt_loc_list *l;
|
||
|
||
for (l = e->locs; l; l = l->next)
|
||
{
|
||
rtx t = l->loc;
|
||
|
||
/* Avoid infinite recursion. */
|
||
if (GET_CODE (t) == REG || GET_CODE (t) == MEM)
|
||
continue;
|
||
else if (rtx_equal_for_cselib_p (t, y))
|
||
return 1;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
if (GET_CODE (y) == VALUE)
|
||
{
|
||
cselib_val *e = CSELIB_VAL_PTR (y);
|
||
struct elt_loc_list *l;
|
||
|
||
for (l = e->locs; l; l = l->next)
|
||
{
|
||
rtx t = l->loc;
|
||
|
||
if (GET_CODE (t) == REG || GET_CODE (t) == MEM)
|
||
continue;
|
||
else if (rtx_equal_for_cselib_p (x, t))
|
||
return 1;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
if (GET_CODE (x) != GET_CODE (y) || GET_MODE (x) != GET_MODE (y))
|
||
return 0;
|
||
|
||
/* This won't be handled correctly by the code below. */
|
||
if (GET_CODE (x) == LABEL_REF)
|
||
return XEXP (x, 0) == XEXP (y, 0);
|
||
|
||
code = GET_CODE (x);
|
||
fmt = GET_RTX_FORMAT (code);
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
int j;
|
||
|
||
switch (fmt[i])
|
||
{
|
||
case 'w':
|
||
if (XWINT (x, i) != XWINT (y, i))
|
||
return 0;
|
||
break;
|
||
|
||
case 'n':
|
||
case 'i':
|
||
if (XINT (x, i) != XINT (y, i))
|
||
return 0;
|
||
break;
|
||
|
||
case 'V':
|
||
case 'E':
|
||
/* Two vectors must have the same length. */
|
||
if (XVECLEN (x, i) != XVECLEN (y, i))
|
||
return 0;
|
||
|
||
/* And the corresponding elements must match. */
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
if (! rtx_equal_for_cselib_p (XVECEXP (x, i, j),
|
||
XVECEXP (y, i, j)))
|
||
return 0;
|
||
break;
|
||
|
||
case 'e':
|
||
if (! rtx_equal_for_cselib_p (XEXP (x, i), XEXP (y, i)))
|
||
return 0;
|
||
break;
|
||
|
||
case 'S':
|
||
case 's':
|
||
if (strcmp (XSTR (x, i), XSTR (y, i)))
|
||
return 0;
|
||
break;
|
||
|
||
case 'u':
|
||
/* These are just backpointers, so they don't matter. */
|
||
break;
|
||
|
||
case '0':
|
||
case 't':
|
||
break;
|
||
|
||
/* It is believed that rtx's at this level will never
|
||
contain anything but integers and other rtx's,
|
||
except for within LABEL_REFs and SYMBOL_REFs. */
|
||
default:
|
||
abort ();
|
||
}
|
||
}
|
||
return 1;
|
||
}
|
||
|
||
/* We need to pass down the mode of constants through the hash table
|
||
functions. For that purpose, wrap them in a CONST of the appropriate
|
||
mode. */
|
||
static rtx
|
||
wrap_constant (mode, x)
|
||
enum machine_mode mode;
|
||
rtx x;
|
||
{
|
||
if (GET_CODE (x) != CONST_INT
|
||
&& (GET_CODE (x) != CONST_DOUBLE || GET_MODE (x) != VOIDmode))
|
||
return x;
|
||
if (mode == VOIDmode)
|
||
abort ();
|
||
return gen_rtx_CONST (mode, x);
|
||
}
|
||
|
||
/* Hash an rtx. Return 0 if we couldn't hash the rtx.
|
||
For registers and memory locations, we look up their cselib_val structure
|
||
and return its VALUE element.
|
||
Possible reasons for return 0 are: the object is volatile, or we couldn't
|
||
find a register or memory location in the table and CREATE is zero. If
|
||
CREATE is nonzero, table elts are created for regs and mem.
|
||
MODE is used in hashing for CONST_INTs only;
|
||
otherwise the mode of X is used. */
|
||
|
||
static unsigned int
|
||
hash_rtx (x, mode, create)
|
||
rtx x;
|
||
enum machine_mode mode;
|
||
int create;
|
||
{
|
||
cselib_val *e;
|
||
int i, j;
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
unsigned int hash = 0;
|
||
|
||
code = GET_CODE (x);
|
||
hash += (unsigned) code + (unsigned) GET_MODE (x);
|
||
|
||
switch (code)
|
||
{
|
||
case MEM:
|
||
case REG:
|
||
e = cselib_lookup (x, GET_MODE (x), create);
|
||
if (! e)
|
||
return 0;
|
||
|
||
return e->value;
|
||
|
||
case CONST_INT:
|
||
hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + INTVAL (x);
|
||
return hash ? hash : (unsigned int) CONST_INT;
|
||
|
||
case CONST_DOUBLE:
|
||
/* This is like the general case, except that it only counts
|
||
the integers representing the constant. */
|
||
hash += (unsigned) code + (unsigned) GET_MODE (x);
|
||
if (GET_MODE (x) != VOIDmode)
|
||
for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
|
||
hash += XWINT (x, i);
|
||
else
|
||
hash += ((unsigned) CONST_DOUBLE_LOW (x)
|
||
+ (unsigned) CONST_DOUBLE_HIGH (x));
|
||
return hash ? hash : (unsigned int) CONST_DOUBLE;
|
||
|
||
/* Assume there is only one rtx object for any given label. */
|
||
case LABEL_REF:
|
||
hash
|
||
+= ((unsigned) LABEL_REF << 7) + (unsigned long) XEXP (x, 0);
|
||
return hash ? hash : (unsigned int) LABEL_REF;
|
||
|
||
case SYMBOL_REF:
|
||
hash
|
||
+= ((unsigned) SYMBOL_REF << 7) + (unsigned long) XSTR (x, 0);
|
||
return hash ? hash : (unsigned int) SYMBOL_REF;
|
||
|
||
case PRE_DEC:
|
||
case PRE_INC:
|
||
case POST_DEC:
|
||
case POST_INC:
|
||
case POST_MODIFY:
|
||
case PRE_MODIFY:
|
||
case PC:
|
||
case CC0:
|
||
case CALL:
|
||
case UNSPEC_VOLATILE:
|
||
return 0;
|
||
|
||
case ASM_OPERANDS:
|
||
if (MEM_VOLATILE_P (x))
|
||
return 0;
|
||
|
||
break;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
i = GET_RTX_LENGTH (code) - 1;
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
rtx tem = XEXP (x, i);
|
||
unsigned int tem_hash = hash_rtx (tem, 0, create);
|
||
|
||
if (tem_hash == 0)
|
||
return 0;
|
||
|
||
hash += tem_hash;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
{
|
||
unsigned int tem_hash = hash_rtx (XVECEXP (x, i, j), 0, create);
|
||
|
||
if (tem_hash == 0)
|
||
return 0;
|
||
|
||
hash += tem_hash;
|
||
}
|
||
else if (fmt[i] == 's')
|
||
{
|
||
const unsigned char *p = (const unsigned char *) XSTR (x, i);
|
||
|
||
if (p)
|
||
while (*p)
|
||
hash += *p++;
|
||
}
|
||
else if (fmt[i] == 'i')
|
||
hash += XINT (x, i);
|
||
else if (fmt[i] == '0' || fmt[i] == 't')
|
||
/* unused */;
|
||
else
|
||
abort ();
|
||
}
|
||
|
||
return hash ? hash : 1 + (unsigned int) GET_CODE (x);
|
||
}
|
||
|
||
/* Create a new value structure for VALUE and initialize it. The mode of the
|
||
value is MODE. */
|
||
|
||
static cselib_val *
|
||
new_cselib_val (value, mode)
|
||
unsigned int value;
|
||
enum machine_mode mode;
|
||
{
|
||
cselib_val *e = empty_vals;
|
||
|
||
if (e)
|
||
empty_vals = e->u.next_free;
|
||
else
|
||
e = (cselib_val *) obstack_alloc (&cselib_obstack, sizeof (cselib_val));
|
||
|
||
if (value == 0)
|
||
abort ();
|
||
|
||
e->value = value;
|
||
e->u.val_rtx = gen_rtx_VALUE (mode);
|
||
CSELIB_VAL_PTR (e->u.val_rtx) = e;
|
||
e->addr_list = 0;
|
||
e->locs = 0;
|
||
return e;
|
||
}
|
||
|
||
/* ADDR_ELT is a value that is used as address. MEM_ELT is the value that
|
||
contains the data at this address. X is a MEM that represents the
|
||
value. Update the two value structures to represent this situation. */
|
||
|
||
static void
|
||
add_mem_for_addr (addr_elt, mem_elt, x)
|
||
cselib_val *addr_elt, *mem_elt;
|
||
rtx x;
|
||
{
|
||
struct elt_loc_list *l;
|
||
|
||
/* Avoid duplicates. */
|
||
for (l = mem_elt->locs; l; l = l->next)
|
||
if (GET_CODE (l->loc) == MEM
|
||
&& CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt)
|
||
return;
|
||
|
||
addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
|
||
mem_elt->locs
|
||
= new_elt_loc_list (mem_elt->locs,
|
||
replace_equiv_address_nv (x, addr_elt->u.val_rtx));
|
||
}
|
||
|
||
/* Subroutine of cselib_lookup. Return a value for X, which is a MEM rtx.
|
||
If CREATE, make a new one if we haven't seen it before. */
|
||
|
||
static cselib_val *
|
||
cselib_lookup_mem (x, create)
|
||
rtx x;
|
||
int create;
|
||
{
|
||
enum machine_mode mode = GET_MODE (x);
|
||
void **slot;
|
||
cselib_val *addr;
|
||
cselib_val *mem_elt;
|
||
struct elt_list *l;
|
||
|
||
if (MEM_VOLATILE_P (x) || mode == BLKmode
|
||
|| (FLOAT_MODE_P (mode) && flag_float_store))
|
||
return 0;
|
||
|
||
/* Look up the value for the address. */
|
||
addr = cselib_lookup (XEXP (x, 0), mode, create);
|
||
if (! addr)
|
||
return 0;
|
||
|
||
/* Find a value that describes a value of our mode at that address. */
|
||
for (l = addr->addr_list; l; l = l->next)
|
||
if (GET_MODE (l->elt->u.val_rtx) == mode)
|
||
return l->elt;
|
||
|
||
if (! create)
|
||
return 0;
|
||
|
||
mem_elt = new_cselib_val (++next_unknown_value, mode);
|
||
add_mem_for_addr (addr, mem_elt, x);
|
||
slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
|
||
mem_elt->value, INSERT);
|
||
*slot = mem_elt;
|
||
return mem_elt;
|
||
}
|
||
|
||
/* Walk rtx X and replace all occurrences of REG and MEM subexpressions
|
||
with VALUE expressions. This way, it becomes independent of changes
|
||
to registers and memory.
|
||
X isn't actually modified; if modifications are needed, new rtl is
|
||
allocated. However, the return value can share rtl with X. */
|
||
|
||
rtx
|
||
cselib_subst_to_values (x)
|
||
rtx x;
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
const char *fmt = GET_RTX_FORMAT (code);
|
||
cselib_val *e;
|
||
struct elt_list *l;
|
||
rtx copy = x;
|
||
int i;
|
||
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
for (l = REG_VALUES (REGNO (x)); l; l = l->next)
|
||
if (GET_MODE (l->elt->u.val_rtx) == GET_MODE (x))
|
||
return l->elt->u.val_rtx;
|
||
|
||
abort ();
|
||
|
||
case MEM:
|
||
e = cselib_lookup_mem (x, 0);
|
||
if (! e)
|
||
{
|
||
/* This happens for autoincrements. Assign a value that doesn't
|
||
match any other. */
|
||
e = new_cselib_val (++next_unknown_value, GET_MODE (x));
|
||
}
|
||
return e->u.val_rtx;
|
||
|
||
case CONST_DOUBLE:
|
||
case CONST_INT:
|
||
return x;
|
||
|
||
case POST_INC:
|
||
case PRE_INC:
|
||
case POST_DEC:
|
||
case PRE_DEC:
|
||
case POST_MODIFY:
|
||
case PRE_MODIFY:
|
||
e = new_cselib_val (++next_unknown_value, GET_MODE (x));
|
||
return e->u.val_rtx;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
rtx t = cselib_subst_to_values (XEXP (x, i));
|
||
|
||
if (t != XEXP (x, i) && x == copy)
|
||
copy = shallow_copy_rtx (x);
|
||
|
||
XEXP (copy, i) = t;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
int j, k;
|
||
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
{
|
||
rtx t = cselib_subst_to_values (XVECEXP (x, i, j));
|
||
|
||
if (t != XVECEXP (x, i, j) && XVEC (x, i) == XVEC (copy, i))
|
||
{
|
||
if (x == copy)
|
||
copy = shallow_copy_rtx (x);
|
||
|
||
XVEC (copy, i) = rtvec_alloc (XVECLEN (x, i));
|
||
for (k = 0; k < j; k++)
|
||
XVECEXP (copy, i, k) = XVECEXP (x, i, k);
|
||
}
|
||
|
||
XVECEXP (copy, i, j) = t;
|
||
}
|
||
}
|
||
}
|
||
|
||
return copy;
|
||
}
|
||
|
||
/* Look up the rtl expression X in our tables and return the value it has.
|
||
If CREATE is zero, we return NULL if we don't know the value. Otherwise,
|
||
we create a new one if possible, using mode MODE if X doesn't have a mode
|
||
(i.e. because it's a constant). */
|
||
|
||
cselib_val *
|
||
cselib_lookup (x, mode, create)
|
||
rtx x;
|
||
enum machine_mode mode;
|
||
int create;
|
||
{
|
||
void **slot;
|
||
cselib_val *e;
|
||
unsigned int hashval;
|
||
|
||
if (GET_MODE (x) != VOIDmode)
|
||
mode = GET_MODE (x);
|
||
|
||
if (GET_CODE (x) == VALUE)
|
||
return CSELIB_VAL_PTR (x);
|
||
|
||
if (GET_CODE (x) == REG)
|
||
{
|
||
struct elt_list *l;
|
||
unsigned int i = REGNO (x);
|
||
|
||
for (l = REG_VALUES (i); l; l = l->next)
|
||
if (mode == GET_MODE (l->elt->u.val_rtx))
|
||
return l->elt;
|
||
|
||
if (! create)
|
||
return 0;
|
||
|
||
e = new_cselib_val (++next_unknown_value, GET_MODE (x));
|
||
e->locs = new_elt_loc_list (e->locs, x);
|
||
if (REG_VALUES (i) == 0)
|
||
VARRAY_PUSH_UINT (used_regs, i);
|
||
REG_VALUES (i) = new_elt_list (REG_VALUES (i), e);
|
||
slot = htab_find_slot_with_hash (hash_table, x, e->value, INSERT);
|
||
*slot = e;
|
||
return e;
|
||
}
|
||
|
||
if (GET_CODE (x) == MEM)
|
||
return cselib_lookup_mem (x, create);
|
||
|
||
hashval = hash_rtx (x, mode, create);
|
||
/* Can't even create if hashing is not possible. */
|
||
if (! hashval)
|
||
return 0;
|
||
|
||
slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
|
||
hashval, create ? INSERT : NO_INSERT);
|
||
if (slot == 0)
|
||
return 0;
|
||
|
||
e = (cselib_val *) *slot;
|
||
if (e)
|
||
return e;
|
||
|
||
e = new_cselib_val (hashval, mode);
|
||
|
||
/* We have to fill the slot before calling cselib_subst_to_values:
|
||
the hash table is inconsistent until we do so, and
|
||
cselib_subst_to_values will need to do lookups. */
|
||
*slot = (void *) e;
|
||
e->locs = new_elt_loc_list (e->locs, cselib_subst_to_values (x));
|
||
return e;
|
||
}
|
||
|
||
/* Invalidate any entries in reg_values that overlap REGNO. This is called
|
||
if REGNO is changing. MODE is the mode of the assignment to REGNO, which
|
||
is used to determine how many hard registers are being changed. If MODE
|
||
is VOIDmode, then only REGNO is being changed; this is used when
|
||
invalidating call clobbered registers across a call. */
|
||
|
||
static void
|
||
cselib_invalidate_regno (regno, mode)
|
||
unsigned int regno;
|
||
enum machine_mode mode;
|
||
{
|
||
unsigned int endregno;
|
||
unsigned int i;
|
||
|
||
/* If we see pseudos after reload, something is _wrong_. */
|
||
if (reload_completed && regno >= FIRST_PSEUDO_REGISTER
|
||
&& reg_renumber[regno] >= 0)
|
||
abort ();
|
||
|
||
/* Determine the range of registers that must be invalidated. For
|
||
pseudos, only REGNO is affected. For hard regs, we must take MODE
|
||
into account, and we must also invalidate lower register numbers
|
||
if they contain values that overlap REGNO. */
|
||
endregno = regno + 1;
|
||
if (regno < FIRST_PSEUDO_REGISTER && mode != VOIDmode)
|
||
endregno = regno + HARD_REGNO_NREGS (regno, mode);
|
||
|
||
for (i = 0; i < endregno; i++)
|
||
{
|
||
struct elt_list **l = ®_VALUES (i);
|
||
|
||
/* Go through all known values for this reg; if it overlaps the range
|
||
we're invalidating, remove the value. */
|
||
while (*l)
|
||
{
|
||
cselib_val *v = (*l)->elt;
|
||
struct elt_loc_list **p;
|
||
unsigned int this_last = i;
|
||
|
||
if (i < FIRST_PSEUDO_REGISTER)
|
||
this_last += HARD_REGNO_NREGS (i, GET_MODE (v->u.val_rtx)) - 1;
|
||
|
||
if (this_last < regno)
|
||
{
|
||
l = &(*l)->next;
|
||
continue;
|
||
}
|
||
|
||
/* We have an overlap. */
|
||
unchain_one_elt_list (l);
|
||
|
||
/* Now, we clear the mapping from value to reg. It must exist, so
|
||
this code will crash intentionally if it doesn't. */
|
||
for (p = &v->locs; ; p = &(*p)->next)
|
||
{
|
||
rtx x = (*p)->loc;
|
||
|
||
if (GET_CODE (x) == REG && REGNO (x) == i)
|
||
{
|
||
unchain_one_elt_loc_list (p);
|
||
break;
|
||
}
|
||
}
|
||
if (v->locs == 0)
|
||
n_useless_values++;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* The memory at address MEM_BASE is being changed.
|
||
Return whether this change will invalidate VAL. */
|
||
|
||
static int
|
||
cselib_mem_conflict_p (mem_base, val)
|
||
rtx mem_base;
|
||
rtx val;
|
||
{
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
int i, j;
|
||
|
||
code = GET_CODE (val);
|
||
switch (code)
|
||
{
|
||
/* Get rid of a few simple cases quickly. */
|
||
case REG:
|
||
case PC:
|
||
case CC0:
|
||
case SCRATCH:
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
return 0;
|
||
|
||
case MEM:
|
||
if (GET_MODE (mem_base) == BLKmode
|
||
|| GET_MODE (val) == BLKmode
|
||
|| anti_dependence (val, mem_base))
|
||
return 1;
|
||
|
||
/* The address may contain nested MEMs. */
|
||
break;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
if (cselib_mem_conflict_p (mem_base, XEXP (val, i)))
|
||
return 1;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (val, i); j++)
|
||
if (cselib_mem_conflict_p (mem_base, XVECEXP (val, i, j)))
|
||
return 1;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* For the value found in SLOT, walk its locations to determine if any overlap
|
||
INFO (which is a MEM rtx). */
|
||
|
||
static int
|
||
cselib_invalidate_mem_1 (slot, info)
|
||
void **slot;
|
||
void *info;
|
||
{
|
||
cselib_val *v = (cselib_val *) *slot;
|
||
rtx mem_rtx = (rtx) info;
|
||
struct elt_loc_list **p = &v->locs;
|
||
int had_locs = v->locs != 0;
|
||
|
||
while (*p)
|
||
{
|
||
rtx x = (*p)->loc;
|
||
cselib_val *addr;
|
||
struct elt_list **mem_chain;
|
||
|
||
/* MEMs may occur in locations only at the top level; below
|
||
that every MEM or REG is substituted by its VALUE. */
|
||
if (GET_CODE (x) != MEM
|
||
|| ! cselib_mem_conflict_p (mem_rtx, x))
|
||
{
|
||
p = &(*p)->next;
|
||
continue;
|
||
}
|
||
|
||
/* This one overlaps. */
|
||
/* We must have a mapping from this MEM's address to the
|
||
value (E). Remove that, too. */
|
||
addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0);
|
||
mem_chain = &addr->addr_list;
|
||
for (;;)
|
||
{
|
||
if ((*mem_chain)->elt == v)
|
||
{
|
||
unchain_one_elt_list (mem_chain);
|
||
break;
|
||
}
|
||
|
||
mem_chain = &(*mem_chain)->next;
|
||
}
|
||
|
||
unchain_one_elt_loc_list (p);
|
||
}
|
||
|
||
if (had_locs && v->locs == 0)
|
||
n_useless_values++;
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Invalidate any locations in the table which are changed because of a
|
||
store to MEM_RTX. If this is called because of a non-const call
|
||
instruction, MEM_RTX is (mem:BLK const0_rtx). */
|
||
|
||
static void
|
||
cselib_invalidate_mem (mem_rtx)
|
||
rtx mem_rtx;
|
||
{
|
||
htab_traverse (hash_table, cselib_invalidate_mem_1, mem_rtx);
|
||
}
|
||
|
||
/* Invalidate DEST, which is being assigned to or clobbered. The second and
|
||
the third parameter exist so that this function can be passed to
|
||
note_stores; they are ignored. */
|
||
|
||
static void
|
||
cselib_invalidate_rtx (dest, ignore, data)
|
||
rtx dest;
|
||
rtx ignore ATTRIBUTE_UNUSED;
|
||
void *data ATTRIBUTE_UNUSED;
|
||
{
|
||
while (GET_CODE (dest) == STRICT_LOW_PART || GET_CODE (dest) == SIGN_EXTRACT
|
||
|| GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SUBREG)
|
||
dest = XEXP (dest, 0);
|
||
|
||
if (GET_CODE (dest) == REG)
|
||
cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
|
||
else if (GET_CODE (dest) == MEM)
|
||
cselib_invalidate_mem (dest);
|
||
|
||
/* Some machines don't define AUTO_INC_DEC, but they still use push
|
||
instructions. We need to catch that case here in order to
|
||
invalidate the stack pointer correctly. Note that invalidating
|
||
the stack pointer is different from invalidating DEST. */
|
||
if (push_operand (dest, GET_MODE (dest)))
|
||
cselib_invalidate_rtx (stack_pointer_rtx, NULL_RTX, NULL);
|
||
}
|
||
|
||
/* Record the result of a SET instruction. DEST is being set; the source
|
||
contains the value described by SRC_ELT. If DEST is a MEM, DEST_ADDR_ELT
|
||
describes its address. */
|
||
|
||
static void
|
||
cselib_record_set (dest, src_elt, dest_addr_elt)
|
||
rtx dest;
|
||
cselib_val *src_elt, *dest_addr_elt;
|
||
{
|
||
int dreg = GET_CODE (dest) == REG ? (int) REGNO (dest) : -1;
|
||
|
||
if (src_elt == 0 || side_effects_p (dest))
|
||
return;
|
||
|
||
if (dreg >= 0)
|
||
{
|
||
if (REG_VALUES (dreg) == 0)
|
||
VARRAY_PUSH_UINT (used_regs, dreg);
|
||
|
||
REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
|
||
if (src_elt->locs == 0)
|
||
n_useless_values--;
|
||
src_elt->locs = new_elt_loc_list (src_elt->locs, dest);
|
||
}
|
||
else if (GET_CODE (dest) == MEM && dest_addr_elt != 0)
|
||
{
|
||
if (src_elt->locs == 0)
|
||
n_useless_values--;
|
||
add_mem_for_addr (dest_addr_elt, src_elt, dest);
|
||
}
|
||
}
|
||
|
||
/* Describe a single set that is part of an insn. */
|
||
struct set
|
||
{
|
||
rtx src;
|
||
rtx dest;
|
||
cselib_val *src_elt;
|
||
cselib_val *dest_addr_elt;
|
||
};
|
||
|
||
/* There is no good way to determine how many elements there can be
|
||
in a PARALLEL. Since it's fairly cheap, use a really large number. */
|
||
#define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)
|
||
|
||
/* Record the effects of any sets in INSN. */
|
||
static void
|
||
cselib_record_sets (insn)
|
||
rtx insn;
|
||
{
|
||
int n_sets = 0;
|
||
int i;
|
||
struct set sets[MAX_SETS];
|
||
rtx body = PATTERN (insn);
|
||
rtx cond = 0;
|
||
|
||
body = PATTERN (insn);
|
||
if (GET_CODE (body) == COND_EXEC)
|
||
{
|
||
cond = COND_EXEC_TEST (body);
|
||
body = COND_EXEC_CODE (body);
|
||
}
|
||
|
||
/* Find all sets. */
|
||
if (GET_CODE (body) == SET)
|
||
{
|
||
sets[0].src = SET_SRC (body);
|
||
sets[0].dest = SET_DEST (body);
|
||
n_sets = 1;
|
||
}
|
||
else if (GET_CODE (body) == PARALLEL)
|
||
{
|
||
/* Look through the PARALLEL and record the values being
|
||
set, if possible. Also handle any CLOBBERs. */
|
||
for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
|
||
{
|
||
rtx x = XVECEXP (body, 0, i);
|
||
|
||
if (GET_CODE (x) == SET)
|
||
{
|
||
sets[n_sets].src = SET_SRC (x);
|
||
sets[n_sets].dest = SET_DEST (x);
|
||
n_sets++;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Look up the values that are read. Do this before invalidating the
|
||
locations that are written. */
|
||
for (i = 0; i < n_sets; i++)
|
||
{
|
||
rtx dest = sets[i].dest;
|
||
|
||
/* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
|
||
the low part after invalidating any knowledge about larger modes. */
|
||
if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
|
||
sets[i].dest = dest = XEXP (dest, 0);
|
||
|
||
/* We don't know how to record anything but REG or MEM. */
|
||
if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
|
||
{
|
||
rtx src = sets[i].src;
|
||
if (cond)
|
||
src = gen_rtx_IF_THEN_ELSE (GET_MODE (src), cond, src, dest);
|
||
sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1);
|
||
if (GET_CODE (dest) == MEM)
|
||
sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0), Pmode, 1);
|
||
else
|
||
sets[i].dest_addr_elt = 0;
|
||
}
|
||
}
|
||
|
||
/* Invalidate all locations written by this insn. Note that the elts we
|
||
looked up in the previous loop aren't affected, just some of their
|
||
locations may go away. */
|
||
note_stores (body, cselib_invalidate_rtx, NULL);
|
||
|
||
/* Now enter the equivalences in our tables. */
|
||
for (i = 0; i < n_sets; i++)
|
||
{
|
||
rtx dest = sets[i].dest;
|
||
if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
|
||
cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
|
||
}
|
||
}
|
||
|
||
/* Record the effects of INSN. */
|
||
|
||
void
|
||
cselib_process_insn (insn)
|
||
rtx insn;
|
||
{
|
||
int i;
|
||
rtx x;
|
||
|
||
cselib_current_insn = insn;
|
||
|
||
/* Forget everything at a CODE_LABEL, a volatile asm, or a setjmp. */
|
||
if (GET_CODE (insn) == CODE_LABEL
|
||
|| (GET_CODE (insn) == CALL_INSN
|
||
&& find_reg_note (insn, REG_SETJMP, NULL))
|
||
|| (GET_CODE (insn) == INSN
|
||
&& GET_CODE (PATTERN (insn)) == ASM_OPERANDS
|
||
&& MEM_VOLATILE_P (PATTERN (insn))))
|
||
{
|
||
clear_table (0);
|
||
return;
|
||
}
|
||
|
||
if (! INSN_P (insn))
|
||
{
|
||
cselib_current_insn = 0;
|
||
return;
|
||
}
|
||
|
||
/* If this is a call instruction, forget anything stored in a
|
||
call clobbered register, or, if this is not a const call, in
|
||
memory. */
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
|
||
if (call_used_regs[i])
|
||
cselib_invalidate_regno (i, VOIDmode);
|
||
|
||
if (! CONST_OR_PURE_CALL_P (insn))
|
||
cselib_invalidate_mem (callmem);
|
||
}
|
||
|
||
cselib_record_sets (insn);
|
||
|
||
#ifdef AUTO_INC_DEC
|
||
/* Clobber any registers which appear in REG_INC notes. We
|
||
could keep track of the changes to their values, but it is
|
||
unlikely to help. */
|
||
for (x = REG_NOTES (insn); x; x = XEXP (x, 1))
|
||
if (REG_NOTE_KIND (x) == REG_INC)
|
||
cselib_invalidate_rtx (XEXP (x, 0), NULL_RTX, NULL);
|
||
#endif
|
||
|
||
/* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
|
||
after we have processed the insn. */
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
|
||
if (GET_CODE (XEXP (x, 0)) == CLOBBER)
|
||
cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0), NULL_RTX, NULL);
|
||
|
||
cselib_current_insn = 0;
|
||
|
||
if (n_useless_values > MAX_USELESS_VALUES)
|
||
remove_useless_values ();
|
||
}
|
||
|
||
/* Make sure our varrays are big enough. Not called from any cselib routines;
|
||
it must be called by the user if it allocated new registers. */
|
||
|
||
void
|
||
cselib_update_varray_sizes ()
|
||
{
|
||
unsigned int nregs = max_reg_num ();
|
||
|
||
if (nregs == cselib_nregs)
|
||
return;
|
||
|
||
cselib_nregs = nregs;
|
||
VARRAY_GROW (reg_values, nregs);
|
||
VARRAY_GROW (used_regs, nregs);
|
||
}
|
||
|
||
/* Initialize cselib for one pass. The caller must also call
|
||
init_alias_analysis. */
|
||
|
||
void
|
||
cselib_init ()
|
||
{
|
||
/* These are only created once. */
|
||
if (! callmem)
|
||
{
|
||
gcc_obstack_init (&cselib_obstack);
|
||
cselib_startobj = obstack_alloc (&cselib_obstack, 0);
|
||
|
||
callmem = gen_rtx_MEM (BLKmode, const0_rtx);
|
||
ggc_add_rtx_root (&callmem, 1);
|
||
}
|
||
|
||
cselib_nregs = max_reg_num ();
|
||
VARRAY_ELT_LIST_INIT (reg_values, cselib_nregs, "reg_values");
|
||
VARRAY_UINT_INIT (used_regs, cselib_nregs, "used_regs");
|
||
hash_table = htab_create (31, get_value_hash, entry_and_rtx_equal_p, NULL);
|
||
clear_table (1);
|
||
}
|
||
|
||
/* Called when the current user is done with cselib. */
|
||
|
||
void
|
||
cselib_finish ()
|
||
{
|
||
clear_table (0);
|
||
VARRAY_FREE (reg_values);
|
||
VARRAY_FREE (used_regs);
|
||
htab_delete (hash_table);
|
||
}
|