combine: distribute_notes again (PR69567, PR64682)

As it happens the patch I did over a year ago for PR64682 isn't quite
correct.  This is PR69567.  This fixes it.


	PR rtl-optimization/64682
	PR rtl-optimization/69567
	* combine.c (distribute_notes) <REG_DEAD>: Place the death note
	before I2 only if the register is both used and set in I2.

From-SVN: r233159

gcc/ChangeLog

+2016-02-04  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/64682
+	PR rtl-optimization/69567
+	* combine.c (distribute_notes) <REG_DEAD>: Place the death note
+	before I2 only if the register is both used and set in I2.
+
 2016-02-04  DJ Delorie  <dj@redhat.com>
 
 	* config/msp430/msp430.c (msp430_start_function): Add function type.

gcc/combine.c

@@ -13901,6 +13901,7 @@ distribute_notes (rtx notes, rtx_insn *from_insn, rtx_insn *i3, rtx_insn *i2,
 	    tem_insn = from_insn;
 	  else
 	    {
+	      tem_insn = i3;
 	      if (from_insn
 		  && CALL_P (from_insn)
 		  && find_reg_fusage (from_insn, USE, XEXP (note, 0)))
@@ -13909,7 +13910,14 @@ distribute_notes (rtx notes, rtx_insn *from_insn, rtx_insn *i3, rtx_insn *i2,
 		place = i3;
 	      else if (i2 != 0 && next_nonnote_nondebug_insn (i2) == i3
 		       && reg_referenced_p (XEXP (note, 0), PATTERN (i2)))
-		place = i2;
+		{
+		  place = i2;
+		  /* If the new I2 sets the same register that is marked dead
+		     in the note, the note now should not be put on I2, as the
+		     note refers to a previous incarnation of the reg.  */
+		  if (reg_set_p (XEXP (note, 0), PATTERN (i2)))
+		    tem_insn = i2;
+		}
 	      else if ((rtx_equal_p (XEXP (note, 0), elim_i2)
 			&& !(i2mod
 			     && reg_overlap_mentioned_p (XEXP (note, 0),
@@ -13917,12 +13925,6 @@ distribute_notes (rtx notes, rtx_insn *from_insn, rtx_insn *i3, rtx_insn *i2,
 		       || rtx_equal_p (XEXP (note, 0), elim_i1)
 		       || rtx_equal_p (XEXP (note, 0), elim_i0))
 		break;
-	      tem_insn = i3;
-	      /* If the new I2 sets the same register that is marked dead
-		 in the note, the note now should not be put on I2, as the
-		 note refers to a previous incarnation of the reg.  */
-	      if (i2 != 0 && reg_set_p (XEXP (note, 0), PATTERN (i2)))
-		tem_insn = i2;
 	    }
 
 	  if (place == 0)