[PATCH] More REG_EQ* notes cleanups

[Steven Bosscher <stevenb dot gcc at gmail dot com>]

Hi,

This patch makes us use set_unique_reg_note in more places in gcc/*.
Also makes us use find_reg_equal_equiv_note in alias.c, instead of
going through REG_NOTES to find one ourselves.

The patch is mostly mechanical, but there is one interesting change
to local-alloc.c.  We used to turn REG_EQUAL notes into REG_EQUIV
notes if the note datum was invariant.  But this is wrong if there
is more than one set to the register that the REG_EQUAL note applies
to.  We later on check whether a reg with a REG_EQUIV note has more
than one set, and if it does, we remove the REG_EQUIV note.  So what
we end up doing is basically throwing away a REG_EQUAL note.  Roger
Sayle pointed this out some time ago on IRC, and I thought I might
as well fix this while I'm working on that code.

Bootstrapped and tested all languages except java (but including ada)
on {i686,x86_64}-unknown-linux-gnu.
OK for the trunk?

Gr.
Steven



	* fwprop.c (try_fwprop_subst): Use set_unique_reg_note
	to add the REG_EQ* note.
	* see.c (see_merge_one_use_extension): Likewise.
	* local-alloc.c (update_equiv_regs): Likewise.  Also don't
	turn REG_EQUAL notes into REG_EQUIV notes if the target
	register may have more than one set.
	* function.c (assign_parm_setup_reg): Use set_unique_reg_note.
	* gcse.c (try_replace_reg): Likewise.
	* alias.c (init_alias_analysis): Use find_reg_equal_equiv_note.
	* calls.c (fixup_tail_calls): Likewise.  Abort if there is
	more than one REG_EQUIV note.
	* reload1.c (gen_reload): Use set_unique_reg_note.

Index: fwprop.c
===================================================================
--- fwprop.c	(revision 121794)
+++ fwprop.c	(working copy)
@@ -691,9 +691,10 @@ try_fwprop_subst (struct df_ref *use, rt
 	  if (dump_file)
 	    fprintf (dump_file, " Setting REG_EQUAL note\n");
 
-	  REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EQUAL, copy_rtx (new),
-						REG_NOTES (insn));
+	  set_unique_reg_note (insn, REG_EQUAL, copy_rtx (new));
 
+	  /* ??? Is this still necessary if we add the note through
+	     set_unique_reg_note?  */
           if (!CONSTANT_P (new))
 	    update_df (insn, loc, DF_INSN_USES (df, def_insn),
 		       type, DF_REF_IN_NOTE);
Index: see.c
===================================================================
--- see.c	(revision 121794)
+++ see.c	(working copy)
@@ -2612,7 +2612,8 @@ see_merge_one_use_extension (void **slot
 	/* Replacement failed.  Remove the note.  */
 	remove_note (ref_copy, note);
       else
-	XEXP (note, 0) = simplified_note;
+	set_unique_reg_note (ref_copy, REG_NOTE_KIND (note),
+			     simplified_note);
     }
 
   if (!see_want_to_be_merged_with_extension (ref, use_se, USE_EXTENSION))
Index: local-alloc.c
===================================================================
--- local-alloc.c	(revision 121794)
+++ local-alloc.c	(working copy)
@@ -930,8 +930,13 @@ update_equiv_regs (void)
 
 	  /* If this register is known to be equal to a constant, record that
 	     it is always equivalent to the constant.  */
-	  if (note && ! rtx_varies_p (XEXP (note, 0), 0))
-	    PUT_MODE (note, (enum machine_mode) REG_EQUIV);
+	  if (REG_N_SETS (regno) == 1
+	      && note && ! rtx_varies_p (XEXP (note, 0), 0))
+	    {
+	      rtx note_value = XEXP (note, 0);
+	      remove_note (insn, note);
+	      set_unique_reg_note (insn, REG_EQUIV, note_value);
+	    }
 
 	  /* If this insn introduces a "constant" register, decrease the priority
 	     of that register.  Record this insn if the register is only used once
@@ -953,9 +958,7 @@ update_equiv_regs (void)
 	  if (note == 0 && REG_BASIC_BLOCK (regno) >= 0
 	      && MEM_P (SET_SRC (set))
 	      && validate_equiv_mem (insn, dest, SET_SRC (set)))
-	    REG_NOTES (insn) = note = gen_rtx_EXPR_LIST (REG_EQUIV,
-			    				 copy_rtx (SET_SRC (set)),
-							 REG_NOTES (insn));
+	    note = set_unique_reg_note (insn, REG_EQUIV, copy_rtx (SET_SRC (set)));
 
 	  if (note)
 	    {
@@ -1061,9 +1064,8 @@ update_equiv_regs (void)
 	  if (validate_equiv_mem (init_insn, src, dest)
 	      && ! memref_used_between_p (dest, init_insn, insn))
 	    {
-	      REG_NOTES (init_insn)
-		= gen_rtx_EXPR_LIST (REG_EQUIV, copy_rtx (dest),
-				     REG_NOTES (init_insn));
+	      set_unique_reg_note (init_insn, REG_EQUIV, copy_rtx (dest));
+
 	      /* This insn makes the equivalence, not the one initializing
 		 the register.  */
 	      reg_equiv_init[regno]
Index: function.c
===================================================================
--- function.c	(revision 121794)
+++ function.c	(working copy)
@@ -2800,20 +2800,14 @@ assign_parm_setup_reg (struct assign_par
 		continue;
 
 	      if (SET_DEST (set) == regno_reg_rtx [regnoi])
-		REG_NOTES (sinsn)
-		  = gen_rtx_EXPR_LIST (REG_EQUIV, stacki,
-				       REG_NOTES (sinsn));
+		set_unique_reg_note (sinsn, REG_EQUIV, stacki);
 	      else if (SET_DEST (set) == regno_reg_rtx [regnor])
-		REG_NOTES (sinsn)
-		  = gen_rtx_EXPR_LIST (REG_EQUIV, stackr,
-				       REG_NOTES (sinsn));
+		set_unique_reg_note (sinsn, REG_EQUIV, stackr);
 	    }
 	}
       else if ((set = single_set (linsn)) != 0
 	       && SET_DEST (set) == parmreg)
-	REG_NOTES (linsn)
-	  = gen_rtx_EXPR_LIST (REG_EQUIV,
-			       data->stack_parm, REG_NOTES (linsn));
+	set_unique_reg_note (linsn, REG_EQUIV, data->stack_parm);
     }
 
   /* For pointer data type, suggest pointer register.  */
Index: gcse.c
===================================================================
--- gcse.c	(revision 121794)
+++ gcse.c	(working copy)
@@ -2668,7 +2668,8 @@ try_replace_reg (rtx from, rtx to, rtx i
   /* If there is already a REG_EQUAL note, update the expression in it
      with our replacement.  */
   if (note != 0 && REG_NOTE_KIND (note) == REG_EQUAL)
-    XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
+    set_unique_reg_note (insn, REG_EQUAL,
+			 simplify_replace_rtx (XEXP (note, 0), from, to));
 
   if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
     {
Index: alias.c
===================================================================
--- alias.c	(revision 121794)
+++ alias.c	(working copy)
@@ -2546,10 +2546,12 @@ init_alias_analysis (void)
 		  rtx src = SET_SRC (set);
 		  rtx t;
 
-		  if (REG_NOTES (insn) != 0
-		      && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0
-			   && REG_N_SETS (regno) == 1)
-			  || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0)
+		  note = find_reg_equal_equiv_note (insn);
+		  if (note && REG_NOTE_KIND (note) == REG_EQUAL
+		      && REG_N_SETS (regno) != 1)
+		    note = NULL_RTX;
+
+		  if (note != NULL_RTX
 		      && GET_CODE (XEXP (note, 0)) != EXPR_LIST
 		      && ! rtx_varies_p (XEXP (note, 0), 1)
 		      && ! reg_overlap_mentioned_p (SET_DEST (set),
Index: calls.c
===================================================================
--- calls.c	(revision 121794)
+++ calls.c	(working copy)
@@ -3130,24 +3130,19 @@ fixup_tail_calls (void)
 
   for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
     {
+      rtx note;
+
       /* There are never REG_EQUIV notes for the incoming arguments
 	 after the NOTE_INSN_FUNCTION_BEG note, so stop if we see it.  */
       if (NOTE_P (insn)
 	  && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
 	break;
 
-      while (1)
-	{
-	  rtx note = find_reg_note (insn, REG_EQUIV, 0);
-	  if (note)
-	    {
-	      /* Remove the note and keep looking at the notes for
-		 this insn.  */
-	      remove_note (insn, note);
-	      continue;
-	    }
-	  break;
-	}
+      note = find_reg_note (insn, REG_EQUIV, 0);
+      if (note)
+	remove_note (insn, note);
+      note = find_reg_note (insn, REG_EQUIV, 0);
+      gcc_assert (!note);
     }
 }
 
Index: reload1.c
===================================================================
--- reload1.c	(revision 121794)
+++ reload1.c	(working copy)
@@ -7832,8 +7832,7 @@ gen_reload (rtx out, rtx in, int opnum, 
       if (insn)
 	{
 	  /* Add a REG_EQUIV note so that find_equiv_reg can find it.  */
-	  REG_NOTES (insn)
-	    = gen_rtx_EXPR_LIST (REG_EQUIV, in, REG_NOTES (insn));
+	  set_unique_reg_note (insn, REG_EQUIV, in);
 	  return insn;
 	}
 
@@ -7842,7 +7841,7 @@ gen_reload (rtx out, rtx in, int opnum, 
 
       gen_reload (out, op1, opnum, type);
       insn = emit_insn (gen_add2_insn (out, op0));
-      REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EQUIV, in, REG_NOTES (insn));
+      set_unique_reg_note (insn, REG_EQUIV, in);
     }
 
 #ifdef SECONDARY_MEMORY_NEEDED
@@ -7902,8 +7901,7 @@ gen_reload (rtx out, rtx in, int opnum, 
       insn = emit_insn_if_valid_for_reload (insn);
       if (insn)
 	{
-	  REG_NOTES (insn)
-	    = gen_rtx_EXPR_LIST (REG_EQUIV, in, REG_NOTES (insn));
+	  set_unique_reg_note (insn, REG_EQUIV, in);
 	  return insn;
 	}