2012-10-26 Richard Biener <rguenther@suse.de>

	PR middle-end/54824
	* tree-optimize.c (execute_fixup_cfg): Insert __builtin_unreachable
	at the end of blocks with no successors.

	* gcc.dg/torture/pr54824.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@192841 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 46 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4d0f9e00dc6..96e604565a7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2012-10-26  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/54824
+	* tree-optimize.c (execute_fixup_cfg): Insert __builtin_unreachable
+	at the end of blocks with no successors.
+
 2012-10-26  Alexander Ivchenko  <alexander.ivchenko@intel.com>
 	    Uros Bizjak  <ubizjak@gmail.com>
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 918af7526fe..c3badec964f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-10-26  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/54824
+	* gcc.dg/torture/pr54824.c: New testcase.
+
 2012-10-26  Alexander Ivchenko  <alexander.ivchenko@intel.com>
 
 	* gcc.target/i386/fxsave-1.c: New.
diff --git a/gcc/testsuite/gcc.dg/torture/pr54824.c b/gcc/testsuite/gcc.dg/torture/pr54824.c
new file mode 100644
index 00000000000..82b822b0993
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr54824.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-w" } */
+
+void __attribute__((noreturn)) bar(void)
+{
+}
+
+void foo(int i, char *p, char *q)
+{
+  while (*p++) {
+      if (i)
+	p++;
+      if (!*q++)
+	bar();
+  }
+}
diff --git a/gcc/tree-optimize.c b/gcc/tree-optimize.c
index d13c04f783c..3e7ca89e94d 100644
--- a/gcc/tree-optimize.c
+++ b/gcc/tree-optimize.c
@@ -180,6 +180,25 @@ execute_fixup_cfg (void)
       FOR_EACH_EDGE (e, ei, bb->succs)
         e->count = (e->count * count_scale
 		    + REG_BR_PROB_BASE / 2) / REG_BR_PROB_BASE;
+
+      /* If we have a basic block with no successors that does not
+	 end with a control statement or a noreturn call end it with
+	 a call to __builtin_unreachable.  This situation can occur
+	 when inlining a noreturn call that does in fact return.  */
+      if (EDGE_COUNT (bb->succs) == 0)
+	{
+	  gimple stmt = last_stmt (bb);
+	  if (!stmt
+	      || (!is_ctrl_stmt (stmt)
+		  && (!is_gimple_call (stmt)
+		      || (gimple_call_flags (stmt) & ECF_NORETURN) == 0)))
+	    {
+	      stmt = gimple_build_call
+		  (builtin_decl_implicit (BUILT_IN_UNREACHABLE), 0);
+	      gimple_stmt_iterator gsi = gsi_last_bb (bb);
+	      gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);
+	    }
+	}
     }
   if (count_scale != REG_BR_PROB_BASE)
     compute_function_frequency ();