PR81285: Fix uninitialised variable in emit_store_flag_int

2017-09-12  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	PR rtl-optimization/82185
	* expmed.c (emit_store_flag_int): Only test tem if it has been
	initialized.

From-SVN: r252008

gcc/ChangeLog

+2017-09-12  Richard Sandiford  <richard.sandiford@linaro.org>
+
+	PR rtl-optimization/82185
+	* expmed.c (emit_store_flag_int): Only test tem if it has been
+	initialized.
+
 2017-09-12  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/82149

gcc/expmed.c

@@ -5601,7 +5601,6 @@ emit_store_flag_int (rtx target, rtx subtarget, enum rtx_code code, rtx op0,
 {
   machine_mode target_mode = target ? GET_MODE (target) : VOIDmode;
   rtx_insn *last = get_last_insn ();
-  rtx tem;
 
   /* If this is an equality comparison of integers, we can try to exclusive-or
      (or subtract) the two operands and use a recursive call to try the
@@ -5610,7 +5609,7 @@ emit_store_flag_int (rtx target, rtx subtarget, enum rtx_code code, rtx op0,
 
   if ((code == EQ || code == NE) && op1 != const0_rtx)
     {
-      tem = expand_binop (mode, xor_optab, op0, op1, subtarget, 1,
+      rtx tem = expand_binop (mode, xor_optab, op0, op1, subtarget, 1,
 			      OPTAB_WIDEN);
 
       if (tem == 0)
@@ -5643,26 +5642,28 @@ emit_store_flag_int (rtx target, rtx subtarget, enum rtx_code code, rtx op0,
 	  && rtx_cost (GEN_INT (normalizep), mode, PLUS, 1,
 		       optimize_insn_for_speed_p ()) == 0)
 	{
-	  tem = emit_store_flag_1 (subtarget, rcode, op0, op1, mode, 0,
+	  rtx tem = emit_store_flag_1 (subtarget, rcode, op0, op1, mode, 0,
 				       STORE_FLAG_VALUE, target_mode);
 	  if (tem != 0)
 	    tem = expand_binop (target_mode, add_optab, tem,
 				gen_int_mode (normalizep, target_mode),
 				target, 0, OPTAB_WIDEN);
+	  if (tem != 0)
+	    return tem;
 	}
       else if (!want_add
 	       && rtx_cost (trueval, mode, XOR, 1,
 			    optimize_insn_for_speed_p ()) == 0)
 	{
-	  tem = emit_store_flag_1 (subtarget, rcode, op0, op1, mode, 0,
+	  rtx tem = emit_store_flag_1 (subtarget, rcode, op0, op1, mode, 0,
 				       normalizep, target_mode);
 	  if (tem != 0)
 	    tem = expand_binop (target_mode, xor_optab, tem, trueval, target,
 				INTVAL (trueval) >= 0, OPTAB_WIDEN);
-	}
-
 	  if (tem != 0)
 	    return tem;
+	}
+
       delete_insns_since (last);
     }
 
@@ -5680,7 +5681,7 @@ emit_store_flag_int (rtx target, rtx subtarget, enum rtx_code code, rtx op0,
   /* Try to put the result of the comparison in the sign bit.  Assume we can't
      do the necessary operation below.  */
 
-  tem = 0;
+  rtx tem = 0;
 
   /* To see if A <= 0, compute (A | (A - 1)).  A <= 0 iff that result has
      the sign bit set.  */