diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0e81d1af04e..bbe300f6f60 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2012-01-27  Richard Henderson  <rth@redhat.com>
+
+	* target.def (TARGET_ATOMIC_TEST_AND_SET_TRUEVAL): New.
+	* c-cppbuiltin.c (cpp_atomic_builtins): Define
+	__GCC_ATOMIC_TEST_AND_SET_TRUEVAL.
+	* doc/tm.texi.in (TARGET_ATOMIC_TEST_AND_SET_TRUEVAL): Add doc hook.
+	* doc/tm.texi: Rebuild.
+
 2012-01-27  Richard Henderson  <rth@redhat.com>
 
 	* optabs.c (gen_atomic_test_and_set): Remove default.
diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c
index 7e7b9c15876..608dba6ecd4 100644
--- a/gcc/c-family/c-cppbuiltin.c
+++ b/gcc/c-family/c-cppbuiltin.c
@@ -670,6 +670,11 @@ cpp_atomic_builtins (cpp_reader *pfile)
   builtin_define_with_int_value ("__GCC_ATOMIC_LLONG_LOCK_FREE", 
 		(have_swap[SWAP_INDEX (long_long_integer_type_node)]? 2 : 1));
 
+  /* If we're dealing with a "set" value that doesn't exactly correspond
+     to a boolean truth value, let the library work around that.  */
+  builtin_define_with_int_value ("__GCC_ATOMIC_TEST_AND_SET_TRUEVAL",
+				 targetm.atomic_test_and_set_trueval);
+
   /* ptr_type_node can't be used here since ptr_mode is only set when
      toplev calls backend_init which is not done with -E  or pch.  */
   psize = POINTER_SIZE / BITS_PER_UNIT;
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index ceb0d1ea4de..91e4b047fe5 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -11359,3 +11359,7 @@ value of @code{TARGET_CONST_ANCHOR} is a power of 2.  For example, on
 MIPS, where add-immediate takes a 16-bit signed value,
 @code{TARGET_CONST_ANCHOR} is set to @samp{0x8000}.  The default value
 is zero, which disables this optimization.  @end deftypevr
+
+@deftypevr {Target Hook} {unsigned char} TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+This value should be set if the result written by @code{atomic_test_and_set} is not exactly 1, i.e. the @code{bool} @code{true}.
+@end deftypevr
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 55c8432c3bf..0ebc15d5ebf 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -11237,3 +11237,5 @@ value of @code{TARGET_CONST_ANCHOR} is a power of 2.  For example, on
 MIPS, where add-immediate takes a 16-bit signed value,
 @code{TARGET_CONST_ANCHOR} is set to @samp{0x8000}.  The default value
 is zero, which disables this optimization.  @end deftypevr
+
+@hook TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
diff --git a/gcc/target.def b/gcc/target.def
index f86f782b020..6084b21dca5 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -2667,6 +2667,13 @@ DEFHOOK
  enum unwind_info_type, (void),
  default_debug_unwind_info)
 
+DEFHOOKPOD
+(atomic_test_and_set_trueval,
+ "This value should be set if the result written by\
+ @code{atomic_test_and_set} is not exactly 1, i.e. the\
+ @code{bool} @code{true}.",
+ unsigned char, 1)
+ 
 /* Leave the boolean fields at the end.  */
 
 /* True if we can create zeroed data by switching to a BSS section