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From abe76789f8e7ce61b357f693eaed5b28feab5ce2 Mon Sep 17 00:00:00 2001
From: Hollis Blanchard <hollis_blanchard@mentor.com>
Date: Mon, 13 Aug 2018 12:11:33 -0700
Subject: [PATCH] Fix build break around __atomic_*() with GCC<4.7
The __atomic_* GCC primitives were introduced in GCC 4.7, but Red Hat
Enterprise Linux 6.x (for example) provides GCC 4.4. Tweak the current code to
use the (most conservative) __sync_synchronize() primitive provided by those
older GCC versions.
(Really, no __atomic or __sync operations are needed here at all, since POSIX
4.12 "Memory Synchronization" says pthread_mutex_lock() and
pthread_mutex_unlock() "synchronize memory with respect to other threads"...)
Signed-off-by: Hollis Blanchard <hollis_blanchard@mentor.com>
---
src/label_file.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/src/label_file.h b/src/label_file.h
index 2fa85474..47859baf 100644
--- a/src/label_file.h
+++ b/src/label_file.h
@@ -351,8 +351,14 @@ static inline int compile_regex(struct saved_data *data, struct spec *spec,
* init_routine does not take a parameter, it's not possible
* to use, so we generate the same effect with atomics and a
* mutex */
+#ifdef __ATOMIC_RELAXED
regex_compiled =
__atomic_load_n(&spec->regex_compiled, __ATOMIC_ACQUIRE);
+#else
+ /* GCC <4.7 */
+ __sync_synchronize();
+ regex_compiled = spec->regex_compiled;
+#endif
if (regex_compiled) {
return 0; /* already done */
}
@@ -360,8 +366,14 @@ static inline int compile_regex(struct saved_data *data, struct spec *spec,
__pthread_mutex_lock(&spec->regex_lock);
/* Check if another thread compiled the regex while we waited
* on the mutex */
+#ifdef __ATOMIC_RELAXED
regex_compiled =
__atomic_load_n(&spec->regex_compiled, __ATOMIC_ACQUIRE);
+#else
+ /* GCC <4.7 */
+ __sync_synchronize();
+ regex_compiled = spec->regex_compiled;
+#endif
if (regex_compiled) {
__pthread_mutex_unlock(&spec->regex_lock);
return 0;
@@ -404,7 +416,13 @@ static inline int compile_regex(struct saved_data *data, struct spec *spec,
}
/* Done. */
+#ifdef __ATOMIC_RELAXED
__atomic_store_n(&spec->regex_compiled, true, __ATOMIC_RELEASE);
+#else
+ /* GCC <4.7 */
+ spec->regex_compiled = true;
+ __sync_synchronize();
+#endif
__pthread_mutex_unlock(&spec->regex_lock);
return 0;
}
--
2.13.0
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