(add_insn_{before,after}): Abort if insertion point is a deleted insn.

From-SVN: r8193

gcc/emit-rtl.c

@@ -2132,7 +2132,7 @@ add_insn (insn)
 
 /* Add INSN into the doubly-linked list after insn AFTER.  This and
    the next should be the only functions called to insert an insn once
-   delay slots have been filled since only they knows how to update a
+   delay slots have been filled since only they know how to update a
    SEQUENCE.  */
 
 void
@@ -2141,6 +2141,9 @@ add_insn_after (insn, after)
 {
   rtx next = NEXT_INSN (after);
 
+  if (INSN_DELETED_P (after))
+    abort ();
+
   NEXT_INSN (insn) = next;
   PREV_INSN (insn) = after;
 
@@ -2174,7 +2177,7 @@ add_insn_after (insn, after)
 
 /* Add INSN into the doubly-linked list before insn BEFORE.  This and
    the previous should be the only functions called to insert an insn once
-   delay slots have been filled since only they knows how to update a
+   delay slots have been filled since only they know how to update a
    SEQUENCE.  */
 
 void
@@ -2183,6 +2186,9 @@ add_insn_before (insn, before)
 {
   rtx prev = PREV_INSN (before);
 
+  if (INSN_DELETED_P (before))
+    abort ();
+
   PREV_INSN (insn) = prev;
   NEXT_INSN (insn) = before;