jump.c (cleanup_barriers): Handle case of no insns before a barrier.

2009-06-17  David Daney  <ddaney@caviumnetworks.com>

	* jump.c (cleanup_barriers): Handle case of no insns before a
	barrier.

2009-06-17  David Daney  <ddaney@caviumnetworks.com>

	* gcc.dg/builtin-unreachable-3.c: New test.

From-SVN: r148624

gcc/ChangeLog

+2009-06-17  David Daney  <ddaney@caviumnetworks.com>
+
+	* jump.c (cleanup_barriers): Handle case of no insns before a
+	barrier.
+
 2009-06-17  David Edelsohn  <edelsohn@gnu.org>
 
 	* config/rs6000/dfp.md (nabsdd2_fpr): Correct mode.

gcc/jump.c

@@ -113,6 +113,8 @@ cleanup_barriers (void)
       if (BARRIER_P (insn))
 	{
 	  prev = prev_nonnote_insn (insn);
+	  if (!prev)
+	    continue;
 	  if (BARRIER_P (prev))
 	    delete_insn (insn);
 	  else if (prev != PREV_INSN (insn))

gcc/testsuite/ChangeLog

 2009-06-17  David Daney  <ddaney@caviumnetworks.com>
 
+	* gcc.dg/builtin-unreachable-3.c: New test.
+
+2009-06-17  David Daney  <ddaney@caviumnetworks.com>
+
 	* gcc.target/i386/builtin-unreachable.c: New test.
 
 2009-06-17  Ian Lance Taylor  <iant@google.com>

gcc/testsuite/gcc.dg/builtin-unreachable-3.c

+/* Check that a function containing only __builtin_unreachable()
+   doesn't ICE.  */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+const char *
+f (void)
+{
+  __builtin_unreachable ();
+}