2015-06-03 Christophe Lyon <christophe.lyon@linaro.org>

	libstdc++/
	Backport from trunk r222324.
	2015-04-22  Renlin Li  <renlin.li@arm.com>

	* testsuite/lib/dg-options.exp (dg-require-thread-fence): New.
	* testsuite/lib/libstdc++.exp (check_v3_target_thread_fence): New.
	* testsuite/29_atomics/atomic_flag/clear/1.cc: Use it.
	* testsuite/29_atomics/atomic_flag/test_and_set/explicit.cc: Likewise.
	* testsuite/29_atomics/atomic_flag/test_and_set/implicit.cc: Likewise.

Change-Id: I25bafadd87fc7c8b5471d93b81948c9b26d5a83b

5 files changed, 68 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_flag/clear/1.cc b/libstdc++-v3/testsuite/29_atomics/atomic_flag/clear/1.cc
index 0a4219c17a8..a6e229945e3 100644
--- a/libstdc++-v3/testsuite/29_atomics/atomic_flag/clear/1.cc
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_flag/clear/1.cc
@@ -1,4 +1,5 @@
 // { dg-options "-std=gnu++11" }
+// { dg-require-thread-fence "" }
 
 // Copyright (C) 2009-2015 Free Software Foundation, Inc.
 //
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit.cc b/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit.cc
index 2ff740b5779..0655be41d2d 100644
--- a/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit.cc
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit.cc
@@ -1,4 +1,5 @@
 // { dg-options "-std=gnu++11" }
+// { dg-require-thread-fence "" }
 
 // Copyright (C) 2008-2015 Free Software Foundation, Inc.
 //
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/implicit.cc b/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/implicit.cc
index 6ac20c077b5..a867da2edfc 100644
--- a/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/implicit.cc
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/implicit.cc
@@ -1,4 +1,5 @@
 // { dg-options "-std=gnu++11" }
+// { dg-require-thread-fence "" }
 
 // Copyright (C) 2008-2015 Free Software Foundation, Inc.
 //
diff --git a/libstdc++-v3/testsuite/lib/dg-options.exp b/libstdc++-v3/testsuite/lib/dg-options.exp
index 38c8206ad44..56ca89617ab 100644
--- a/libstdc++-v3/testsuite/lib/dg-options.exp
+++ b/libstdc++-v3/testsuite/lib/dg-options.exp
@@ -115,6 +115,15 @@ proc dg-require-cmath { args } {
     return
 }
 
+proc dg-require-thread-fence { args } {
+    if { ![ check_v3_target_thread_fence ] } {
+	upvar dg-do-what dg-do-what
+	set dg-do-what [list [lindex ${dg-do-what} 0] "N" "P"]
+	return
+    }
+    return
+}
+
 proc dg-require-atomic-builtins { args } {
     if { ![ check_v3_target_atomic_builtins ] } {
 	upvar dg-do-what dg-do-what
diff --git a/libstdc++-v3/testsuite/lib/libstdc++.exp b/libstdc++-v3/testsuite/lib/libstdc++.exp
index b2f7d0030af..6a6374a8e6b 100644
--- a/libstdc++-v3/testsuite/lib/libstdc++.exp
+++ b/libstdc++-v3/testsuite/lib/libstdc++.exp
@@ -1221,6 +1221,62 @@ proc check_v3_target_cmath { } {
     return $et_c99_math
 }
 
+proc check_v3_target_thread_fence { } {
+    global cxxflags
+    global DEFAULT_CXXFLAGS
+    global et_thread_fence
+
+    global tool
+
+    if { ![info exists et_thread_fence_target_name] } {
+	set et_thread_fence_target_name ""
+    }
+
+    # If the target has changed since we set the cached value, clear it.
+    set current_target [current_target_name]
+    if { $current_target != $et_thread_fence_target_name } {
+	verbose "check_v3_target_thread_fence: `$et_thread_fence_target_name'" 2
+	set et_thread_fence_target_name $current_target
+	if [info exists et_thread_fence] {
+	    verbose "check_v3_target_thread_fence: removing cached result" 2
+	    unset et_thread_fence
+	}
+    }
+
+    if [info exists et_thread_fence] {
+	verbose "check_v3_target_thread_fence: using cached result" 2
+    } else {
+	set et_thread_fence 0
+
+	# Set up and preprocess a C++11 test program that depends
+	# on the thread fence to be available.
+	set src thread_fence[pid].cc
+
+	set f [open $src "w"]
+	puts $f "int main() {"
+	puts $f "__atomic_thread_fence (__ATOMIC_SEQ_CST);"
+	puts $f "return 0;"
+	puts $f "}"
+	close $f
+
+	set cxxflags_saved $cxxflags
+	set cxxflags "$cxxflags $DEFAULT_CXXFLAGS -Werror -std=gnu++11"
+
+	set lines [v3_target_compile $src /dev/null executable ""]
+	set cxxflags $cxxflags_saved
+	file delete $src
+
+	if [string match "" $lines] {
+	    # No error message, linking succeeded.
+	    set et_thread_fence 1
+	} else {
+	    verbose "check_v3_target_thread_fence: compilation failed" 2
+	}
+    }
+    verbose "check_v3_target_thread_fence: $et_thread_fence" 2
+    return $et_thread_fence
+}
+
 proc check_v3_target_atomic_builtins { } {
     global cxxflags
     global DEFAULT_CXXFLAGS