re PR rtl-optimization/36929 (internal compiler error: Segmentation fault)

PR rtl-optimization/36929
* dse.c (replace_inc_dec): Use emit_insn_before instead of
add_insn_before and fix argument order.
(replace_inc_dec_mem): Handle NULL rtx.

From-SVN: r138333

gcc/dse.c

@@ -783,10 +783,9 @@ replace_inc_dec (rtx *r, void *d)
       {
 	rtx r1 = XEXP (x, 0);
 	rtx c = gen_int_mode (Pmode, data->size);
-	add_insn_before (data->insn, 
-			 gen_rtx_SET (Pmode, r1, 
-				      gen_rtx_PLUS (Pmode, r1, c)),
-			 NULL);
+	emit_insn_before (gen_rtx_SET (Pmode, r1, 
+				       gen_rtx_PLUS (Pmode, r1, c)),
+			  data->insn);
 	return -1;
       }
 		 
@@ -795,10 +794,9 @@ replace_inc_dec (rtx *r, void *d)
       {
 	rtx r1 = XEXP (x, 0);
 	rtx c = gen_int_mode (Pmode, -data->size);
-	add_insn_before (data->insn, 
-			 gen_rtx_SET (Pmode, r1, 
-				      gen_rtx_PLUS (Pmode, r1, c)),
-			 NULL);
+	emit_insn_before (gen_rtx_SET (Pmode, r1, 
+				       gen_rtx_PLUS (Pmode, r1, c)),
+			  data->insn);
 	return -1;
       }
 	
@@ -809,8 +807,7 @@ replace_inc_dec (rtx *r, void *d)
 	   insn that contained it.  */
 	rtx add = XEXP (x, 0);
 	rtx r1 = XEXP (add, 0);
-	add_insn_before (data->insn, 
-			 gen_rtx_SET (Pmode, r1, add), NULL);
+	emit_insn_before (gen_rtx_SET (Pmode, r1, add), data->insn);
 	return -1;
       }
 
@@ -827,12 +824,12 @@ static int
 replace_inc_dec_mem (rtx *r, void *d)
 {
   rtx x = *r;
-  if (GET_CODE (x) == MEM)
+  if (x != NULL_RTX && MEM_P (x))
     {
       struct insn_size data;
 
       data.size = GET_MODE_SIZE (GET_MODE (x));
-      data.insn = (rtx)d;
+      data.insn = (rtx) d;
 
       for_each_rtx (&XEXP (x, 0), replace_inc_dec, &data);