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[patch] Merge equivalent invariants in loop-invariant.c


Hello,

one feature missing in the loop-invariant.c invariant motion with
respect to the loop.c one is the fact that it does not recognize
the situation when one invariant is defined multiple times inside
the loop, and all the instances are considered separately.

This patch makes loop-invariant.c to recognize this situation,
and to move just one instance of the computation out of the loop,
and remove the other definitions.

Bootstrapped and regtested on i686.

Zdenek

	* Makefile.in (loop-invariant.o): Add HASHTAB_H dependency.
	* df.c (df_find_use): New function.
	* df.h (df_find_use): Declare.
	* loop-invariant.c: Include hashtab.h.
	(struct invariant): Replace processed field by reg field.
	Add eqto field.
	(struct invariant_expr_entry): New.
	(df): New global variable.
	(invariant_for_use, hash_invariant_expr_1, invariant_expr_equal_p,
	hash_invariant_expr, eq_invariant_expr, find_or_insert_inv,
	find_identical_invariants, merge_identical_invariants): New functions.
	(find_defs, check_dependencies, find_invariant_insn,
	record_uses, find_invariants_bb, find_invariants_body,
	find_invariants, find_invariants_to_move, move_invariants,
	free_inv_motion_data, move_single_loop_invariants,
	move_loop_invariants): Do not pass df in arguments.
	(create_new_invariant): Return the new invariant.  Initialize new
	fields.
	(find_invariants): Call merge_identical_invariants.
	(get_inv_cost, best_gain_for_invariant, set_move_mark,
	move_invariant_reg): Handle equivalent invariants.

Index: Makefile.in
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Makefile.in,v
retrieving revision 1.1454
diff -c -3 -p -r1.1454 Makefile.in
*** Makefile.in	16 Mar 2005 06:03:18 -0000	1.1454
--- Makefile.in	16 Mar 2005 19:05:22 -0000
*************** loop-iv.o : loop-iv.c $(CONFIG_H) $(SYST
*** 2065,2071 ****
     $(BASIC_BLOCK_H) hard-reg-set.h $(CFGLOOP_H) $(EXPR_H) coretypes.h $(TM_H)
  loop-invariant.o : loop-invariant.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) $(GGC_H) \
     $(BASIC_BLOCK_H) hard-reg-set.h cfgloop.h $(EXPR_H) coretypes.h $(TM_H) \
!    function.h $(FLAGS_H) df.h
  cfgloopmanip.o : cfgloopmanip.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) \
     $(BASIC_BLOCK_H) hard-reg-set.h $(CFGLOOP_H) $(CFGLAYOUT_H) output.h coretypes.h $(TM_H)
  loop-init.o : loop-init.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) \
--- 2070,2076 ----
     $(BASIC_BLOCK_H) hard-reg-set.h $(CFGLOOP_H) $(EXPR_H) coretypes.h $(TM_H)
  loop-invariant.o : loop-invariant.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) $(GGC_H) \
     $(BASIC_BLOCK_H) hard-reg-set.h cfgloop.h $(EXPR_H) coretypes.h $(TM_H) \
!    function.h $(FLAGS_H) df.h $(HASHTAB_H)
  cfgloopmanip.o : cfgloopmanip.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) \
     $(BASIC_BLOCK_H) hard-reg-set.h $(CFGLOOP_H) $(CFGLAYOUT_H) output.h coretypes.h $(TM_H)
  loop-init.o : loop-init.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) \
Index: df.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/df.c,v
retrieving revision 1.84
diff -c -3 -p -r1.84 df.c
*** df.c	17 Feb 2005 16:19:27 -0000	1.84
--- df.c	16 Mar 2005 19:05:22 -0000
*************** df_find_def (struct df *df, rtx insn, rt
*** 3036,3041 ****
--- 3036,3056 ----
    return NULL;
  }
  
+ /* Finds the reference corresponding to the use of REG in INSN.
+    DF is the dataflow object.  */
+ 
+ struct ref *
+ df_find_use (struct df *df, rtx insn, rtx reg)
+ {
+   struct df_link *uses;
+ 
+   for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next)
+     if (rtx_equal_p (DF_REF_REG (uses->ref), reg))
+       return uses->ref;
+ 
+   return NULL;
+ }
+ 
  /* Return 1 if REG is referenced in INSN, zero otherwise.  */ 
  
  int
Index: df.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/df.h,v
retrieving revision 1.32
diff -c -3 -p -r1.32 df.h
*** df.h	10 Feb 2005 18:46:31 -0000	1.32
--- df.h	16 Mar 2005 19:05:22 -0000
*************** extern struct ref *df_bb_regno_last_def_
*** 290,295 ****
--- 290,297 ----
  
  extern struct ref *df_find_def (struct df *, rtx, rtx);
  
+ extern struct ref *df_find_use (struct df *, rtx, rtx);
+ 
  extern int df_reg_used (struct df *, rtx, rtx);
  
  /* Functions for debugging from GDB.  */
Index: loop-invariant.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/loop-invariant.c,v
retrieving revision 2.11
diff -c -3 -p -r2.11 loop-invariant.c
*** loop-invariant.c	17 Feb 2005 22:41:32 -0000	2.11
--- loop-invariant.c	16 Mar 2005 19:05:23 -0000
*************** Software Foundation, 59 Temple Place - S
*** 49,54 ****
--- 49,55 ----
  #include "function.h"
  #include "flags.h"
  #include "df.h"
+ #include "hashtab.h"
  
  /* The data stored for the loop.  */
  
*************** struct invariant
*** 87,94 ****
    /* The number of the invariant.  */
    unsigned invno;
  
!   /* Whether we already processed the invariant.  */
!   bool processed;
  
    /* The definition of the invariant.  */
    struct def *def;
--- 88,99 ----
    /* The number of the invariant.  */
    unsigned invno;
  
!   /* The number of the invariant with the same value.  */
!   unsigned eqto;
! 
!   /* If we moved the invariant out of the loop, the register that contains its
!      value.  */
!   rtx reg;
  
    /* The definition of the invariant.  */
    struct def *def;
*************** struct invariant
*** 102,108 ****
    /* Whether to move the invariant.  */
    bool move;
  
!   /* Cost if the invariant.  */
    unsigned cost;
  
    /* The invariants it depends on.  */
--- 107,113 ----
    /* Whether to move the invariant.  */
    bool move;
  
!   /* Cost of the invariant.  */
    unsigned cost;
  
    /* The invariants it depends on.  */
*************** struct invariant
*** 113,118 ****
--- 118,140 ----
    unsigned stamp;
  };
  
+ /* Entry for hash table of invariant expressions.  */
+ 
+ struct invariant_expr_entry
+ {
+   /* The invariant.  */
+   struct invariant *inv;
+ 
+   /* Its value.  */
+   rtx expr;
+ 
+   /* Its mode.  */
+   enum machine_mode mode;
+ 
+   /* Its hash.  */
+   hashval_t hash;
+ };
+ 
  /* The actual stamp for marking already visited invariants during determining
     costs of movements.  */
  
*************** static unsigned actual_stamp;
*** 122,127 ****
--- 144,153 ----
  
  static varray_type invariants;
  
+ /* The dataflow object.  */
+ 
+ static struct df *df;
+ 
  /* Test for possibility of invariantness of X.  */
  
  static bool
*************** check_maybe_invariant (rtx x)
*** 189,194 ****
--- 215,498 ----
    return true;
  }
  
+ /* Returns the invariant definition for USE, or NULL if USE is not
+    invariant.  */
+ 
+ static struct invariant *
+ invariant_for_use (struct ref *use)
+ {
+   struct df_link *defs;
+   struct ref *def;
+   basic_block bb = BLOCK_FOR_INSN (use->insn), def_bb;
+ 
+   defs = DF_REF_CHAIN (use);
+   if (!defs || defs->next)
+     return NULL;
+   def = defs->ref;
+   if (!DF_REF_DATA (def))
+     return NULL;
+ 
+   def_bb = DF_REF_BB (def);
+   if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb))
+     return NULL;
+   return DF_REF_DATA (def);
+ }
+ 
+ /* Computes hash value for invariant expression X in INSN.  */
+ 
+ static hashval_t
+ hash_invariant_expr_1 (rtx insn, rtx x)
+ {
+   enum rtx_code code = GET_CODE (x);
+   int i, j;
+   const char *fmt;
+   hashval_t val = code;
+   int do_not_record_p;
+   struct ref *use;
+   struct invariant *inv;
+ 
+   switch (code)
+     {
+     case CONST_INT:
+     case CONST_DOUBLE:
+     case SYMBOL_REF:
+     case CONST:
+     case LABEL_REF:
+       return hash_rtx (x, GET_MODE (x), &do_not_record_p, NULL, false);
+ 
+     case REG:
+       use = df_find_use (df, insn, x);
+       if (!use)
+ 	return hash_rtx (x, GET_MODE (x), &do_not_record_p, NULL, false);
+       inv = invariant_for_use (use);
+       if (!inv)
+ 	return hash_rtx (x, GET_MODE (x), &do_not_record_p, NULL, false);
+ 
+       gcc_assert (inv->eqto != ~0u);
+       return inv->eqto;
+ 
+     default:
+       break;
+     }
+ 
+   fmt = GET_RTX_FORMAT (code);
+   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
+     {
+       if (fmt[i] == 'e')
+ 	val ^= hash_invariant_expr_1 (insn, XEXP (x, i));
+       else if (fmt[i] == 'E')
+ 	{
+ 	  for (j = 0; j < XVECLEN (x, i); j++)
+ 	    val ^= hash_invariant_expr_1 (insn, XVECEXP (x, i, j));
+ 	}
+     }
+ 
+   return val;
+ }
+ 
+ /* Compares invariant expressions E1 and E2 in modes MODE1 and MODE2 used in
+    insns INSN1 and INSN2.  */
+ 
+ static bool
+ invariant_expr_equal_p (rtx insn1, rtx e1, enum machine_mode mode1,
+ 			rtx insn2, rtx e2, enum machine_mode mode2)
+ {
+   enum rtx_code code = GET_CODE (e1);
+   int i, j;
+   const char *fmt;
+   struct ref *use1, *use2;
+   struct invariant *inv1 = NULL, *inv2 = NULL;
+   rtx sub1, sub2;
+   enum machine_mode submode1, submode2;
+ 
+   gcc_assert (GET_MODE (e1) == VOIDmode || GET_MODE (e1) == mode1);
+   gcc_assert (GET_MODE (e2) == VOIDmode || GET_MODE (e2) == mode2);
+ 
+   if (code != GET_CODE (e2) || mode1 != mode2)
+     return false;
+ 
+   switch (code)
+     {
+     case CONST_INT:
+     case CONST_DOUBLE:
+     case SYMBOL_REF:
+     case CONST:
+     case LABEL_REF:
+       return rtx_equal_p (e1, e2);
+ 
+     case REG:
+       use1 = df_find_use (df, insn1, e1);
+       use2 = df_find_use (df, insn2, e2);
+       if (use1)
+ 	inv1 = invariant_for_use (use1);
+       if (use2)
+ 	inv2 = invariant_for_use (use2);
+ 
+       if (!inv1 && !inv2)
+ 	return rtx_equal_p (e1, e2);
+ 
+       if (!inv1 || !inv2)
+ 	return false;
+       
+       gcc_assert (inv1->eqto != ~0u);
+       gcc_assert (inv2->eqto != ~0u);
+       return inv1->eqto == inv2->eqto;
+ 
+     default:
+       break;
+     }
+ 
+   fmt = GET_RTX_FORMAT (code);
+   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
+     {
+       if (fmt[i] == 'e')
+ 	{
+ 	  sub1 = XEXP (e1, i);
+ 	  sub2 = XEXP (e2, i);
+ 	  submode1 = GET_MODE (sub1);
+ 	  if (submode1 == VOIDmode)
+ 	    submode1 = mode1;
+ 	  submode2 = GET_MODE (sub2);
+ 	  if (submode2 == VOIDmode)
+ 	    submode2 = mode2;
+ 
+ 	  if (!invariant_expr_equal_p (insn1, sub1, submode1,
+ 				       insn2, sub2, submode2))
+ 	    return false;
+ 	}
+ 
+       else if (fmt[i] == 'E')
+ 	{
+ 	  if (XVECLEN (e1, i) != XVECLEN (e2, i))
+ 	    return false;
+ 
+ 	  for (j = 0; j < XVECLEN (e1, i); j++)
+ 	    {
+ 	      sub1 = XVECEXP (e1, i, j);
+ 	      sub2 = XVECEXP (e2, i, j);
+ 	      submode1 = GET_MODE (sub1);
+ 	      if (submode1 == VOIDmode)
+ 		submode1 = mode1;
+ 	      submode2 = GET_MODE (sub2);
+ 	      if (submode2 == VOIDmode)
+ 		submode2 = mode2;
+ 
+ 	      if (!invariant_expr_equal_p (insn1, sub1, submode1,
+ 					   insn2, sub2, submode2))
+ 		return false;
+ 	    }
+ 	}
+     }
+ 
+   return true;
+ }
+ 
+ /* Returns hash value for invariant expression entry E.  */
+ 
+ static hashval_t
+ hash_invariant_expr (const void *e)
+ {
+   const struct invariant_expr_entry *entry = e;
+ 
+   return entry->hash;
+ }
+ 
+ /* Compares invariant expression entries E1 and E2.  */
+ 
+ static int
+ eq_invariant_expr (const void *e1, const void *e2)
+ {
+   const struct invariant_expr_entry *entry1 = e1;
+   const struct invariant_expr_entry *entry2 = e2;
+ 
+   return invariant_expr_equal_p (entry1->inv->insn, entry1->expr, entry1->mode,
+ 				 entry2->inv->insn, entry2->expr, entry2->mode);
+ }
+ 
+ /* Checks whether invariant with value EXPR in machine mode MODE is
+    recorded in EQ.  If this is the case, return the invariant.  Otherwise
+    insert INV to the table for this expression and return INV.  */
+ 
+ static struct invariant *
+ find_or_insert_inv (htab_t eq, rtx expr, enum machine_mode mode,
+ 		    struct invariant *inv)
+ {
+   hashval_t hash = hash_invariant_expr_1 (inv->insn, expr);
+   struct invariant_expr_entry *entry;
+   struct invariant_expr_entry pentry;
+   PTR *slot;
+   
+   pentry.expr = expr;
+   pentry.inv = inv;
+   pentry.mode = mode;
+   slot = htab_find_slot_with_hash (eq, &pentry, hash, INSERT);
+   entry = *slot;
+ 
+   if (entry)
+     return entry->inv;
+ 
+   entry = xmalloc (sizeof (struct invariant_expr_entry));
+   entry->inv = inv;
+   entry->expr = expr;
+   entry->mode = mode;
+   entry->hash = hash;
+   *slot = entry;
+ 
+   return inv;
+ }
+ 
+ /* Finds invariants identical to INV and records the equivalence.  EQ is the
+    hash table of the invariants.  */
+ 
+ static void
+ find_identical_invariants (htab_t eq, struct invariant *inv)
+ {
+   unsigned depno;
+   bitmap_iterator bi;
+   struct invariant *dep;
+   rtx expr, set;
+   enum machine_mode mode;
+ 
+   if (inv->eqto != ~0u)
+     return;
+ 
+   EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, depno, bi)
+     {
+       dep = VARRAY_GENERIC_PTR_NOGC (invariants, depno);
+       find_identical_invariants (eq, dep);
+     }
+ 
+   set = single_set (inv->insn);
+   expr = SET_SRC (set);
+   mode = GET_MODE (SET_DEST (set));
+   inv->eqto = find_or_insert_inv (eq, expr, mode, inv)->invno;
+ 
+   if (dump_file && inv->eqto != inv->invno)
+     fprintf (dump_file,
+ 	     "Invariant %d is equivalent to invariant %d.\n ",
+ 	     inv->invno, inv->eqto);
+ }
+ 
+ /* Find invariants with the same value and record the equivalences.  */
+ 
+ static void
+ merge_identical_invariants (void)
+ {
+   unsigned i;
+   struct invariant *inv;
+   htab_t eq = htab_create (VARRAY_ACTIVE_SIZE (invariants),
+ 			   hash_invariant_expr, eq_invariant_expr, free);
+ 
+   for (i = 0; i < VARRAY_ACTIVE_SIZE (invariants); i++)
+     {
+       inv = VARRAY_GENERIC_PTR_NOGC (invariants, i);
+ 
+       find_identical_invariants (eq, inv);
+     }
+ 
+   htab_delete (eq);
+ }
+ 
  /* Determines the basic blocks inside LOOP that are always executed and
     stores their bitmap to ALWAYS_REACHED.  MAY_EXIT is a bitmap of
     basic blocks that may either exit the loop, or contain the call that
*************** may_assign_reg_p (rtx x)
*** 289,299 ****
    return can_copy_p (GET_MODE (x));
  }
  
! /* Finds definitions that may correspond to invariants in LOOP with body BODY.
!    DF is the dataflow object.  */
  
  static void
! find_defs (struct loop *loop, basic_block *body, struct df *df)
  {
    unsigned i;
    bitmap blocks = BITMAP_ALLOC (NULL);
--- 593,603 ----
    return can_copy_p (GET_MODE (x));
  }
  
! /* Finds definitions that may correspond to invariants in LOOP with body
!    BODY.  */
  
  static void
! find_defs (struct loop *loop, basic_block *body)
  {
    unsigned i;
    bitmap blocks = BITMAP_ALLOC (NULL);
*************** find_defs (struct loop *loop, basic_bloc
*** 307,315 ****
  
  /* Creates a new invariant for definition DEF in INSN, depending on invariants
     in DEPENDS_ON.  ALWAYS_EXECUTED is true if the insn is always executed,
!    unless the program ends due to a function call.  */
  
! static void
  create_new_invariant (struct def *def, rtx insn, bitmap depends_on,
  		      bool always_executed)
  {
--- 611,620 ----
  
  /* Creates a new invariant for definition DEF in INSN, depending on invariants
     in DEPENDS_ON.  ALWAYS_EXECUTED is true if the insn is always executed,
!    unless the program ends due to a function call.  The newly created invariant
!    is returned.  */
  
! static struct invariant *
  create_new_invariant (struct def *def, rtx insn, bitmap depends_on,
  		      bool always_executed)
  {
*************** create_new_invariant (struct def *def, r
*** 328,338 ****
      inv->cost = rtx_cost (SET_SRC (set), SET);
  
    inv->move = false;
!   inv->processed = false;
    inv->stamp = 0;
    inv->insn = insn;
  
    inv->invno = VARRAY_ACTIVE_SIZE (invariants);
    if (def)
      def->invno = inv->invno;
    VARRAY_PUSH_GENERIC_PTR_NOGC (invariants, inv);
--- 633,644 ----
      inv->cost = rtx_cost (SET_SRC (set), SET);
  
    inv->move = false;
!   inv->reg = NULL_RTX;
    inv->stamp = 0;
    inv->insn = insn;
  
    inv->invno = VARRAY_ACTIVE_SIZE (invariants);
+   inv->eqto = ~0u;
    if (def)
      def->invno = inv->invno;
    VARRAY_PUSH_GENERIC_PTR_NOGC (invariants, inv);
*************** create_new_invariant (struct def *def, r
*** 344,349 ****
--- 650,657 ----
  	       INSN_UID (insn), inv->invno, inv->cost);
        dump_bitmap (dump_file, inv->depends_on);
      }
+ 
+   return inv;
  }
  
  /* Record USE at DEF.  */
*************** record_use (struct def *def, rtx *use, r
*** 366,380 ****
  }
  
  /* Finds the invariants INSN depends on and store them to the DEPENDS_ON
!    bitmap.  DF is the dataflow object.  */
  
  static bool
! check_dependencies (rtx insn, struct df *df, bitmap depends_on)
  {
    struct df_link *uses, *defs;
    struct ref *use, *def;
    basic_block bb = BLOCK_FOR_INSN (insn), def_bb;
    struct def *def_data;
    
    for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next)
      {
--- 674,689 ----
  }
  
  /* Finds the invariants INSN depends on and store them to the DEPENDS_ON
!    bitmap.  */
  
  static bool
! check_dependencies (rtx insn, bitmap depends_on)
  {
    struct df_link *uses, *defs;
    struct ref *use, *def;
    basic_block bb = BLOCK_FOR_INSN (insn), def_bb;
    struct def *def_data;
+   struct invariant *inv;
    
    for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next)
      {
*************** check_dependencies (rtx insn, struct df 
*** 388,397 ****
  	return false;
  
        def = defs->ref;
!       def_data = DF_REF_DATA (def);
!       if (!def_data)
  	return false;
  
        def_bb = DF_REF_BB (def);
        if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb))
  	return false;
--- 697,709 ----
  	return false;
  
        def = defs->ref;
!       inv = DF_REF_DATA (def);
!       if (!inv)
  	return false;
  
+       def_data = inv->def;
+       gcc_assert (def_data != NULL);
+ 
        def_bb = DF_REF_BB (def);
        if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb))
  	return false;
*************** check_dependencies (rtx insn, struct df 
*** 404,421 ****
  
  /* Finds invariant in INSN.  ALWAYS_REACHED is true if the insn is always
     executed.  ALWAYS_EXECUTED is true if the insn is always executed,
!    unless the program ends due to a function call.  DF is the dataflow
!    object.  */
  
  static void
! find_invariant_insn (rtx insn, bool always_reached, bool always_executed,
! 		     struct df *df)
  {
    struct ref *ref;
    struct def *def;
    bitmap depends_on;
    rtx set, dest;
    bool simple = true;
  
    /* Until we get rid of LIBCALLS.  */
    if (find_reg_note (insn, REG_RETVAL, NULL_RTX)
--- 716,732 ----
  
  /* Finds invariant in INSN.  ALWAYS_REACHED is true if the insn is always
     executed.  ALWAYS_EXECUTED is true if the insn is always executed,
!    unless the program ends due to a function call.  */
  
  static void
! find_invariant_insn (rtx insn, bool always_reached, bool always_executed)
  {
    struct ref *ref;
    struct def *def;
    bitmap depends_on;
    rtx set, dest;
    bool simple = true;
+   struct invariant *inv;
  
    /* Until we get rid of LIBCALLS.  */
    if (find_reg_note (insn, REG_RETVAL, NULL_RTX)
*************** find_invariant_insn (rtx insn, bool alwa
*** 448,521 ****
      }
  
    depends_on = BITMAP_ALLOC (NULL);
!   if (!check_dependencies (insn, df, depends_on))
      {
        BITMAP_FREE (depends_on);
        return;
      }
  
    if (simple)
!     {
!       ref = df_find_def (df, insn, dest);
!       def = xcalloc (1, sizeof (struct def));
!       DF_REF_DATA (ref) = def;
!     }
    else
      def = NULL;
  
!   create_new_invariant (def, insn, depends_on, always_executed);
  }
  
! /* Record registers used in INSN that have an unique invariant definition.
!    DF is the dataflow object.  */
  
  static void
! record_uses (rtx insn, struct df *df)
  {
!   struct df_link *uses, *defs;
!   struct ref *use, *def;
!   basic_block bb = BLOCK_FOR_INSN (insn), def_bb;
    
    for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next)
      {
        use = uses->ref;
! 
!       defs = DF_REF_CHAIN (use);
!       if (!defs || defs->next)
! 	continue;
!       def = defs->ref;
!       if (!DF_REF_DATA (def))
! 	continue;
! 
!       def_bb = DF_REF_BB (def);
!       if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb))
! 	continue;
! 
!       record_use (DF_REF_DATA (def), DF_REF_LOC (use), DF_REF_INSN (use));
      }
  }
  
  /* Finds invariants in INSN.  ALWAYS_REACHED is true if the insn is always
     executed.  ALWAYS_EXECUTED is true if the insn is always executed,
!    unless the program ends due to a function call.  DF is the dataflow
!    object.  */
  
  static void
! find_invariants_insn (rtx insn, bool always_reached, bool always_executed,
! 		      struct df *df)
  {
!   find_invariant_insn (insn, always_reached, always_executed, df);
!   record_uses (insn, df);
  }
  
  /* Finds invariants in basic block BB.  ALWAYS_REACHED is true if the
     basic block is always executed.  ALWAYS_EXECUTED is true if the basic
     block is always executed, unless the program ends due to a function
!    call.  DF is the dataflow object.  */
  
  static void
! find_invariants_bb (basic_block bb, bool always_reached, bool always_executed,
! 		    struct df *df)
  {
    rtx insn;
  
--- 759,820 ----
      }
  
    depends_on = BITMAP_ALLOC (NULL);
!   if (!check_dependencies (insn, depends_on))
      {
        BITMAP_FREE (depends_on);
        return;
      }
  
    if (simple)
!     def = xcalloc (1, sizeof (struct def));
    else
      def = NULL;
  
!   inv = create_new_invariant (def, insn, depends_on, always_executed);
! 
!   if (simple)
!     {
!       ref = df_find_def (df, insn, dest);
!       DF_REF_DATA (ref) = inv;
!     }
  }
  
! /* Record registers used in INSN that have an unique invariant definition.  */
  
  static void
! record_uses (rtx insn)
  {
!   struct df_link *uses;
!   struct ref *use;
!   struct invariant *inv;
    
    for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next)
      {
        use = uses->ref;
!       inv = invariant_for_use (use);
!       if (inv)
! 	record_use (inv->def, DF_REF_LOC (use), DF_REF_INSN (use));
      }
  }
  
  /* Finds invariants in INSN.  ALWAYS_REACHED is true if the insn is always
     executed.  ALWAYS_EXECUTED is true if the insn is always executed,
!    unless the program ends due to a function call.  */
  
  static void
! find_invariants_insn (rtx insn, bool always_reached, bool always_executed)
  {
!   find_invariant_insn (insn, always_reached, always_executed);
!   record_uses (insn);
  }
  
  /* Finds invariants in basic block BB.  ALWAYS_REACHED is true if the
     basic block is always executed.  ALWAYS_EXECUTED is true if the basic
     block is always executed, unless the program ends due to a function
!    call.  */
  
  static void
! find_invariants_bb (basic_block bb, bool always_reached, bool always_executed)
  {
    rtx insn;
  
*************** find_invariants_bb (basic_block bb, bool
*** 524,530 ****
        if (!INSN_P (insn))
  	continue;
  
!       find_invariants_insn (insn, always_reached, always_executed, df);
  
        if (always_reached
  	  && CALL_P (insn)
--- 823,829 ----
        if (!INSN_P (insn))
  	continue;
  
!       find_invariants_insn (insn, always_reached, always_executed);
  
        if (always_reached
  	  && CALL_P (insn)
*************** find_invariants_bb (basic_block bb, bool
*** 536,561 ****
  /* Finds invariants in LOOP with body BODY.  ALWAYS_REACHED is the bitmap of
     basic blocks in BODY that are always executed.  ALWAYS_EXECUTED is the
     bitmap of basic blocks in BODY that are always executed unless the program
!    ends due to a function call.  DF is the dataflow object.  */
  
  static void
  find_invariants_body (struct loop *loop, basic_block *body,
! 		      bitmap always_reached, bitmap always_executed,
! 		      struct df *df)
  {
    unsigned i;
  
    for (i = 0; i < loop->num_nodes; i++)
      find_invariants_bb (body[i],
  			bitmap_bit_p (always_reached, i),
! 			bitmap_bit_p (always_executed, i),
! 			df);
  }
  
! /* Finds invariants in LOOP.  DF is the dataflow object.  */
  
  static void
! find_invariants (struct loop *loop, struct df *df)
  {
    bitmap may_exit = BITMAP_ALLOC (NULL);
    bitmap always_reached = BITMAP_ALLOC (NULL);
--- 835,858 ----
  /* Finds invariants in LOOP with body BODY.  ALWAYS_REACHED is the bitmap of
     basic blocks in BODY that are always executed.  ALWAYS_EXECUTED is the
     bitmap of basic blocks in BODY that are always executed unless the program
!    ends due to a function call.  */
  
  static void
  find_invariants_body (struct loop *loop, basic_block *body,
! 		      bitmap always_reached, bitmap always_executed)
  {
    unsigned i;
  
    for (i = 0; i < loop->num_nodes; i++)
      find_invariants_bb (body[i],
  			bitmap_bit_p (always_reached, i),
! 			bitmap_bit_p (always_executed, i));
  }
  
! /* Finds invariants in LOOP.  */
  
  static void
! find_invariants (struct loop *loop)
  {
    bitmap may_exit = BITMAP_ALLOC (NULL);
    bitmap always_reached = BITMAP_ALLOC (NULL);
*************** find_invariants (struct loop *loop, stru
*** 567,574 ****
    compute_always_reached (loop, body, may_exit, always_reached);
    compute_always_reached (loop, body, has_exit, always_executed);
  
!   find_defs (loop, body, df);
!   find_invariants_body (loop, body, always_reached, always_executed, df);
  
    BITMAP_FREE (always_reached);
    BITMAP_FREE (always_executed);
--- 864,872 ----
    compute_always_reached (loop, body, may_exit, always_reached);
    compute_always_reached (loop, body, has_exit, always_executed);
  
!   find_defs (loop, body);
!   find_invariants_body (loop, body, always_reached, always_executed);
!   merge_identical_invariants ();
  
    BITMAP_FREE (always_reached);
    BITMAP_FREE (always_executed);
*************** get_inv_cost (struct invariant *inv, int
*** 603,608 ****
--- 901,909 ----
    struct invariant *dep;
    bitmap_iterator bi;
  
+   /* Find the representative of the class of the equivalent invariants.  */
+   inv = VARRAY_GENERIC_PTR_NOGC (invariants, inv->eqto);
+ 
    *comp_cost = 0;
    *regs_needed = 0;
    if (inv->move
*************** best_gain_for_invariant (struct invarian
*** 680,685 ****
--- 981,990 ----
        if (inv->move)
  	continue;
  
+       /* Only consider the "representatives" of equivalent invariants.  */
+       if (inv->eqto != inv->invno)
+ 	continue;
+ 
        again = gain_for_invariant (inv, &aregs_needed,
  				  new_regs, regs_used, n_inv_uses);
        if (again > gain)
*************** set_move_mark (unsigned invno)
*** 701,706 ****
--- 1006,1014 ----
    struct invariant *inv = VARRAY_GENERIC_PTR_NOGC (invariants, invno);
    bitmap_iterator bi;
  
+   /* Find the representative of the class of the equivalent invariants.  */
+   inv = VARRAY_GENERIC_PTR_NOGC (invariants, inv->eqto);
+ 
    if (inv->move)
      return;
    inv->move = true;
*************** set_move_mark (unsigned invno)
*** 714,723 ****
      }
  }
  
! /* Determines which invariants to move.  DF is the dataflow object.  */
  
  static void
! find_invariants_to_move (struct df *df)
  {
    unsigned i, regs_used, n_inv_uses, regs_needed = 0, new_regs;
    struct invariant *inv = NULL;
--- 1022,1031 ----
      }
  }
  
! /* Determines which invariants to move.  */
  
  static void
! find_invariants_to_move (void)
  {
    unsigned i, regs_used, n_inv_uses, regs_needed = 0, new_regs;
    struct invariant *inv = NULL;
*************** find_invariants_to_move (struct df *df)
*** 758,799 ****
      }
  }
  
! /* Move invariant INVNO out of the LOOP.  DF is the dataflow object.  */
  
  static void
! move_invariant_reg (struct loop *loop, unsigned invno, struct df *df)
  {
    struct invariant *inv = VARRAY_GENERIC_PTR_NOGC (invariants, invno);
    unsigned i;
    basic_block preheader = loop_preheader_edge (loop)->src;
    rtx reg, set;
    struct use *use;
    bitmap_iterator bi;
  
!   if (inv->processed)
      return;
-   inv->processed = true;
  
!   if (inv->depends_on)
      {
!       EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, i, bi)
  	{
! 	  move_invariant_reg (loop, i, df);
  	}
      }
  
!   /* Move the set out of the loop.  If the set is always executed (we could
!      omit this condition if we know that the register is unused outside of the
!      loop, but it does not seem worth finding out) and it has no uses that
!      would not be dominated by it, we may just move it (TODO).  Otherwise we
!      need to create a temporary register.  */
!   set = single_set (inv->insn);
!   reg = gen_reg_rtx (GET_MODE (SET_DEST (set)));
!   df_pattern_emit_after (df, gen_move_insn (SET_DEST (set), reg),
! 			 BLOCK_FOR_INSN (inv->insn), inv->insn);
!   SET_DEST (set) = reg;
!   reorder_insns (inv->insn, inv->insn, BB_END (preheader));
!   df_insn_modify (df, preheader, inv->insn);
  
    /* Replace the uses we know to be dominated.  It saves work for copy
       propagation, and also it is necessary so that dependent invariants
--- 1066,1125 ----
      }
  }
  
! /* Move invariant INVNO out of the LOOP.  */
  
  static void
! move_invariant_reg (struct loop *loop, unsigned invno)
  {
    struct invariant *inv = VARRAY_GENERIC_PTR_NOGC (invariants, invno);
+   struct invariant *repr = VARRAY_GENERIC_PTR_NOGC (invariants, inv->eqto);
    unsigned i;
    basic_block preheader = loop_preheader_edge (loop)->src;
    rtx reg, set;
    struct use *use;
    bitmap_iterator bi;
  
!   if (inv->reg
!       || !repr->move)
      return;
  
!   /* If this is a representative of the class of equivalent invariants,
!      really move the invariant.  Otherwise just replace its use with
!      the register used for the representative.  */
!   if (inv == repr)
      {
!       if (inv->depends_on)
  	{
! 	  EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, i, bi)
! 	    {
! 	      move_invariant_reg (loop, i);
! 	    }
  	}
+   
+       /* Move the set out of the loop.  If the set is always executed (we could
+ 	 omit this condition if we know that the register is unused outside of the
+ 	 loop, but it does not seem worth finding out) and it has no uses that
+ 	 would not be dominated by it, we may just move it (TODO).  Otherwise we
+ 	 need to create a temporary register.  */
+       set = single_set (inv->insn);
+       reg = gen_reg_rtx (GET_MODE (SET_DEST (set)));
+       df_pattern_emit_after (df, gen_move_insn (SET_DEST (set), reg),
+ 			     BLOCK_FOR_INSN (inv->insn), inv->insn);
+       SET_DEST (set) = reg;
+       reorder_insns (inv->insn, inv->insn, BB_END (preheader));
+       df_insn_modify (df, preheader, inv->insn);
+     }
+   else
+     {
+       move_invariant_reg (loop, repr->invno);
+       reg = repr->reg;
+       set = single_set (inv->insn);
+       df_pattern_emit_after (df, gen_move_insn (SET_DEST (set), reg),
+ 			     BLOCK_FOR_INSN (inv->insn), inv->insn);
+       df_insn_delete (df, BLOCK_FOR_INSN (inv->insn), inv->insn);
      }
  
!   inv->reg = reg;
  
    /* Replace the uses we know to be dominated.  It saves work for copy
       propagation, and also it is necessary so that dependent invariants
*************** move_invariant_reg (struct loop *loop, u
*** 809,818 ****
  }
  
  /* Move selected invariant out of the LOOP.  Newly created regs are marked
!    in TEMPORARY_REGS.  DF is the dataflow object.  */
  
  static void
! move_invariants (struct loop *loop, struct df *df)
  {
    struct invariant *inv;
    unsigned i;
--- 1135,1144 ----
  }
  
  /* Move selected invariant out of the LOOP.  Newly created regs are marked
!    in TEMPORARY_REGS.  */
  
  static void
! move_invariants (struct loop *loop)
  {
    struct invariant *inv;
    unsigned i;
*************** move_invariants (struct loop *loop, stru
*** 820,827 ****
    for (i = 0; i < VARRAY_ACTIVE_SIZE (invariants); i++)
      {
        inv = VARRAY_GENERIC_PTR_NOGC (invariants, i);
!       if (inv->move)
! 	move_invariant_reg (loop, i, df);
      }
  }
  
--- 1146,1152 ----
    for (i = 0; i < VARRAY_ACTIVE_SIZE (invariants); i++)
      {
        inv = VARRAY_GENERIC_PTR_NOGC (invariants, i);
!       move_invariant_reg (loop, i);
      }
  }
  
*************** init_inv_motion_data (void)
*** 836,846 ****
      VARRAY_GENERIC_PTR_NOGC_INIT (invariants, 100, "invariants");
  }
  
! /* Frees the data allocated by invariant motion.  DF is the dataflow
!    object.  */
  
  static void
! free_inv_motion_data (struct df *df)
  {
    unsigned i;
    struct def *def;
--- 1161,1170 ----
      VARRAY_GENERIC_PTR_NOGC_INIT (invariants, 100, "invariants");
  }
  
! /* Frees the data allocated by invariant motion.  */
  
  static void
! free_inv_motion_data (void)
  {
    unsigned i;
    struct def *def;
*************** free_inv_motion_data (struct df *df)
*** 851,859 ****
        if (!df->defs[i])
  	continue;
  
!       def = DF_REF_DATA (df->defs[i]);
!       if (!def)
  	continue;
  
        free_use_list (def->uses);
        free (def);
--- 1175,1185 ----
        if (!df->defs[i])
  	continue;
  
!       inv = DF_REF_DATA (df->defs[i]);
!       if (!inv)
  	continue;
+       def = inv->def;
+       gcc_assert (def != NULL);
  
        free_use_list (def->uses);
        free (def);
*************** free_inv_motion_data (struct df *df)
*** 869,886 ****
    VARRAY_POP_ALL (invariants);
  }
  
! /* Move the invariants out of the LOOP.  DF is the dataflow object.  */
  
  static void
! move_single_loop_invariants (struct loop *loop, struct df *df)
  {
    init_inv_motion_data ();
  
!   find_invariants (loop, df);
!   find_invariants_to_move (df);
!   move_invariants (loop, df);
  
!   free_inv_motion_data (df);
  }
  
  /* Releases the auxiliary data for LOOP.  */
--- 1195,1212 ----
    VARRAY_POP_ALL (invariants);
  }
  
! /* Move the invariants out of the LOOP.  */
  
  static void
! move_single_loop_invariants (struct loop *loop)
  {
    init_inv_motion_data ();
  
!   find_invariants (loop);
!   find_invariants_to_move ();
!   move_invariants (loop);
  
!   free_inv_motion_data ();
  }
  
  /* Releases the auxiliary data for LOOP.  */
*************** move_loop_invariants (struct loops *loop
*** 901,907 ****
  {
    struct loop *loop;
    unsigned i;
!   struct df *df = df_init ();
  
    /* Process the loops, innermost first.  */
    loop = loops->tree_root;
--- 1227,1234 ----
  {
    struct loop *loop;
    unsigned i;
! 
!   df = df_init ();
  
    /* Process the loops, innermost first.  */
    loop = loops->tree_root;
*************** move_loop_invariants (struct loops *loop
*** 910,916 ****
  
    while (loop != loops->tree_root)
      {
!       move_single_loop_invariants (loop, df);
  
        if (loop->next)
  	{
--- 1237,1243 ----
  
    while (loop != loops->tree_root)
      {
!       move_single_loop_invariants (loop);
  
        if (loop->next)
  	{


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