From d573446841743e709c3da79b28051ab4fc18d3fd Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Fri, 24 Feb 2012 06:49:09 +0000
Subject: [PATCH] * configure.in (__builtin_unreachable): check for clang.  
 [ruby-core:42849] * include/ruby/ruby.h (UNREACHABLE): fallback definition.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34784 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog           |  7 +++++++
 configure.in        | 10 ++++++++++
 include/ruby/ruby.h |  3 +++
 3 files changed, 20 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index d5a24f1de5..9e9fc5180d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Fri Feb 24 15:49:07 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (__builtin_unreachable): check for clang.
+	  [ruby-core:42849]
+
+	* include/ruby/ruby.h (UNREACHABLE): fallback definition.
+
 Fri Feb 24 13:54:33 2012  Aaron Patterson <aaron@tenderlovemaking.com>
 
 	* ext/psych/parser.c: prevent a memory leak by protecting calls to
diff --git a/configure.in b/configure.in
index 18ed6b53db..8f9e7d0810 100644
--- a/configure.in
+++ b/configure.in
@@ -908,6 +908,16 @@ if test "$GCC" = yes; then
     if test "$rb_cv_gcc_atomic_builtins" = yes; then
 	AC_DEFINE(HAVE_GCC_ATOMIC_BUILTINS)
     fi
+
+    AC_CACHE_CHECK(for __builtin_unreachable, rb_cv_func___builtin_unreachable,
+    [AC_TRY_LINK([@%:@include <stdlib.h>],
+	[exit(0); __builtin_unreachable();],
+	[rb_cv_func___builtin_unreachable=yes],
+	[rb_cv_func___builtin_unreachable=no])
+    ])
+    if test "$rb_cv_func___builtin_unreachable" = yes; then
+	AC_DEFINE_UNQUOTED(UNREACHABLE, [__builtin_unreachable()])
+    fi
 fi
 
 AC_CACHE_CHECK(for exported function attribute, rb_cv_func_exported, [
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 75f0d71965..898d2e251d 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -36,6 +36,9 @@ extern "C" {
 #ifndef NOINLINE
 # define NOINLINE(x) x
 #endif
+#ifndef UNREACHABLE
+# define UNREACHABLE		/* unreachable */
+#endif
 
 #ifdef __GNUC__
 #define PRINTF_ARGS(decl, string_index, first_to_check) \