gcc/cselib.h

   1 /* Common subexpression elimination for GNU compiler.
   2    Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997,
   3    1998, 1999, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   4    Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 /* Describe a value.  */
  23 typedef struct cselib_val_struct {
  24   /* The hash value.  */
  25   unsigned int hash;
  26
  27   /* A unique id assigned to values.  */
  28   int uid;
  29
  30   /* A VALUE rtx that points back to this structure.  */
  31   rtx val_rtx;
  32
  33   /* All rtl expressions that hold this value at the current time during a
  34      scan.  */
  35   struct elt_loc_list *locs;
  36
  37   /* If this value is used as an address, points to a list of values that
  38      use it as an address in a MEM.  */
  39   struct elt_list *addr_list;
  40
  41   struct cselib_val_struct *next_containing_mem;
  42 } cselib_val;
  43
  44 /* A list of rtl expressions that hold the same value.  */
  45 struct elt_loc_list {
  46   /* Next element in the list.  */
  47   struct elt_loc_list *next;
  48   /* An rtl expression that holds the value.  */
  49   rtx loc;
  50   /* The insn that made the equivalence.  */
  51   rtx setting_insn;
  52 };
  53
  54 /* Describe a single set that is part of an insn.  */
  55 struct cselib_set
  56 {
  57   rtx src;
  58   rtx dest;
  59   cselib_val *src_elt;
  60   cselib_val *dest_addr_elt;
  61 };
  62
  63 enum cselib_record_what
  64 {
  65   CSELIB_RECORD_MEMORY = 1,
  66   CSELIB_PRESERVE_CONSTANTS = 2
  67 };
  68
  69 extern void (*cselib_discard_hook) (cselib_val *);
  70 extern void (*cselib_record_sets_hook) (rtx insn, struct cselib_set *sets,
  71                                         int n_sets);
  72
  73 extern cselib_val *cselib_lookup (rtx, enum machine_mode,
  74                                   int, enum machine_mode);
  75 extern cselib_val *cselib_lookup_from_insn (rtx, enum machine_mode,
  76                                             int, enum machine_mode, rtx);
  77 extern void cselib_init (int);
  78 extern void cselib_clear_table (void);
  79 extern void cselib_finish (void);
  80 extern void cselib_process_insn (rtx);
  81 extern enum machine_mode cselib_reg_set_mode (const_rtx);
  82 extern int rtx_equal_for_cselib_p (rtx, rtx);
  83 extern int references_value_p (const_rtx, int);
  84 extern rtx cselib_expand_value_rtx (rtx, bitmap, int);
  85 typedef rtx (*cselib_expand_callback)(rtx, bitmap, int, void *);
  86 extern rtx cselib_expand_value_rtx_cb (rtx, bitmap, int,
  87                                        cselib_expand_callback, void *);
  88 extern bool cselib_dummy_expand_value_rtx_cb (rtx, bitmap, int,
  89                                               cselib_expand_callback, void *);
  90 extern rtx cselib_subst_to_values (rtx, enum machine_mode);
  91 extern void cselib_invalidate_rtx (rtx);
  92
  93 extern void cselib_reset_table (unsigned int);
  94 extern unsigned int cselib_get_next_uid (void);
  95 extern void cselib_preserve_value (cselib_val *);
  96 extern bool cselib_preserved_value_p (cselib_val *);
  97 extern void cselib_preserve_only_values (void);
  98 extern void cselib_preserve_cfa_base_value (cselib_val *, unsigned int);
  99 extern void cselib_add_permanent_equiv (cselib_val *, rtx, rtx);
 100
 101 extern void dump_cselib_table (FILE *);
 102
 103 /* Return the canonical value for VAL, following the equivalence chain
 104    towards the earliest (== lowest uid) equivalent value.  */
 105
 106 static inline cselib_val *
 107 canonical_cselib_val (cselib_val *val)
 108 {
 109   cselib_val *canon;
 110
 111   if (!val->locs || val->locs->next
 112       || !val->locs->loc || GET_CODE (val->locs->loc) != VALUE
 113       || val->uid < CSELIB_VAL_PTR (val->locs->loc)->uid)
 114     return val;
 115
 116   canon = CSELIB_VAL_PTR (val->locs->loc);
 117   gcc_checking_assert (canonical_cselib_val (canon) == canon);
 118   return canon;
 119 }