jump.c (onlyjump_p): New function.

        * jump.c (onlyjump_p): New function.
        * rtl.h: Declare it.
        * flow.c (delete_unreachable_blocks): Use onlyjump_p instead
        of condjump_p in calling tidy_fallthru_edge and merge_blocks.

From-SVN: r28584

gcc/ChangeLog

+Sat Aug  7 19:32:16 1999  Richard Henderson  <rth@cygnus.com>
+
+	* jump.c (onlyjump_p): New function.
+	* rtl.h: Declare it.
+	* flow.c (delete_unreachable_blocks): Use onlyjump_p instead
+	of condjump_p in calling tidy_fallthru_edge and merge_blocks.
+
 Sat Aug  7 17:09:36 1999  Richard Henderson  <rth@cygnus.com>
 
 	* global.c (build_insn_chain): Use EXECUTE_IF_SET_IN_REG_SET

gcc/flow.c

@@ -1564,11 +1564,9 @@ delete_unreachable_blocks ()
       if ((s = b->succ) != NULL
 	  && s->succ_next == NULL
 	  && 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))
+	  /* If the jump insn has side effects, we can't tidy the edge.  */
+	  && (GET_CODE (b->end) != JUMP_INSN
+	      || onlyjump_p (b->end)))
 	tidy_fallthru_edge (s, b, c);
     }
 
@@ -1587,11 +1585,9 @@ 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)
+	     /* If the jump insn has side effects, we can't kill the edge.  */
+	     && (GET_CODE (b->end) != JUMP_INSN
+		 || onlyjump_p (b->end))
 	     && merge_blocks (s, b, c))
 	continue;
 

gcc/jump.c

@@ -3528,6 +3528,29 @@ returnjump_p (insn)
   return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
 }
 
+/* Return true if INSN is a jump that only transfers control and
+   nothing more.  */
+
+int
+onlyjump_p (insn)
+     rtx insn;
+{
+  rtx set;
+
+  if (GET_CODE (insn) != JUMP_INSN)
+    return 0;
+
+  set = single_set (insn);
+  if (set == NULL)
+    return 0;
+  if (GET_CODE (SET_DEST (set)) != PC)
+    return 0;
+  if (side_effects_p (SET_SRC (set)))
+    return 0;
+
+  return 1;
+}
+
 #ifdef HAVE_cc0
 
 /* Return 1 if X is an RTX that does nothing but set the condition codes

gcc/rtl.h

@@ -1352,6 +1352,7 @@ extern int condjump_p			PROTO ((rtx));
 extern rtx condjump_label		PROTO ((rtx));
 extern int simplejump_p			PROTO ((rtx));
 extern int returnjump_p			PROTO ((rtx));
+extern int onlyjump_p			PROTO ((rtx));
 extern int sets_cc0_p			PROTO ((rtx));
 extern int invert_jump			PROTO ((rtx, rtx));
 extern int rtx_renumbered_equal_p	PROTO ((rtx, rtx));