cfgcleanup.c (old_insns_match_p): Handle the case of empty blocks.

2009-07-25  David Daney  <ddaney@caviumnetworks.com>

	* cfgcleanup.c (old_insns_match_p): Handle the case of empty
	blocks.

2009-07-25  David Daney  <ddaney@caviumnetworks.com>

	* gcc.dg/builtin-unreachable-4.c: New test.

From-SVN: r150089

gcc/ChangeLog

+2009-07-25  David Daney  <ddaney@caviumnetworks.com>
+
+	* cfgcleanup.c (old_insns_match_p): Handle the case of empty
+	blocks.
+	
 2009-07-25  Martin Jambor  <mjambor@suse.cz>
 
 	* c-common.c (c_common_attribute_table): New element for noclone.

gcc/cfgcleanup.c

@@ -953,7 +953,12 @@ old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx i1, rtx i2)
   if (GET_CODE (i1) != GET_CODE (i2))
     return false;
 
-  p1 = PATTERN (i1);
+  /* __builtin_unreachable() may lead to empty blocks (ending with
+     NOTE_INSN_BASIC_BLOCK).  They may be crossjumped. */
+  if (NOTE_INSN_BASIC_BLOCK_P (i1) && NOTE_INSN_BASIC_BLOCK_P (i2))
+    return true;
+
+   p1 = PATTERN (i1);
   p2 = PATTERN (i2);
 
   if (GET_CODE (p1) != GET_CODE (p2))

gcc/testsuite/ChangeLog

+2009-07-25  David Daney  <ddaney@caviumnetworks.com>
+
+	* gcc.dg/builtin-unreachable-4.c: New test.
+
 2009-07-25  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/33197

gcc/testsuite/gcc.dg/builtin-unreachable-4.c

+/* Check that this valid code doesn't ICE.  */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+void
+g (int a, int b, int c, int d)
+{
+  if (d)
+    {
+      ((void)
+       (!(a && b && c) ? __builtin_unreachable (), 0 : 0));
+    }
+  ((void)
+   (!(a && b && c) ? __builtin_unreachable (), 0 : 0));
+}