flow.c (delete_unreachable_blocks): Do not call merge_blocks or tidy_fallthru_edge if...

        * flow.c (delete_unreachable_blocks): Do not call merge_blocks
        or tidy_fallthru_edge if the last insn in the block is not
        an unconditional jump or a simple conditional jump.

From-SVN: r28483

gcc/ChangeLog

+Wed Aug  4 01:08:44 1999  Jeffrey A Law  (law@cygnus.com)
+
+	* flow.c (delete_unreachable_blocks): Do not call merge_blocks
+	or tidy_fallthru_edge if the last insn in the block is not
+	an unconditional jump or a simple conditional jump.
+
 Tue Aug  3 20:21:20 1999  J"orn Rennecke <amylaar@cygnus.co.uk>
 
 	* Makefile.in (c-decl.o): Depends on defaults.h.

gcc/flow.c

@@ -1563,7 +1563,12 @@ delete_unreachable_blocks ()
 	 check that the edge is not a FALLTHRU edge.  */
       if ((s = b->succ) != NULL
 	  && s->succ_next == NULL
-	  && s->dest == c)
+	  && s->dest == c
+	  /* If the last insn is not a normal conditional jump
+	     (or an unconditional jump), then we can not tidy the
+	     fallthru edge because we can not delete the jump.  */
+	  && GET_CODE (b->end) == JUMP_INSN
+	  && condjump_p (b->end))
 	tidy_fallthru_edge (s, b, c);
     }
 
@@ -1582,6 +1587,11 @@ delete_unreachable_blocks ()
 	     && (s->flags & EDGE_EH) == 0
 	     && (c = s->dest) != EXIT_BLOCK_PTR
 	     && c->pred->pred_next == NULL
+	     /* If the last insn is not a normal conditional jump
+		(or an unconditional jump), then we can not merge
+		the blocks because we can not delete the jump.  */
+	     && GET_CODE (b->end) == JUMP_INSN
+	     && condjump_p (b->end)
 	     && merge_blocks (s, b, c))
 	continue;