From c3205d294e519f994829d9355eb133670729aab4 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Fri, 27 Jan 2017 09:15:32 +0100
Subject: atomic: drop __sync builtins

The correctness of the stdatomic.h emulation via the __sync builtins is
questionable, and we've been relying on exact stdatomic semantics for a
while, so just get rid of it. Compilers which support __sync but not
stdatomic.h will use to the slow mutex fallback.

Not sure about the __atomic builtins. It doesn't seem to harm either, so
leave it for now.
---
 wscript | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

(limited to 'wscript')

diff --git a/wscript b/wscript
index a7ec0a9c3d..6ebc3f9fd0 100644
--- a/wscript
+++ b/wscript
@@ -178,20 +178,12 @@ main_dependencies = [
                 'int64_t test = 0;'
                 'test = __atomic_add_fetch(&test, 1, __ATOMIC_SEQ_CST)')),
         'deps_neg': [ 'stdatomic' ],
-    }, {
-        'name': 'sync-builtins',
-        'desc': 'compiler support for __sync built-ins',
-        'func': check_statement('stdint.h',
-                    'int64_t test = 0;'
-                    '__typeof__(test) x = ({int a = 1; a;});'
-                    'test = __sync_add_and_fetch(&test, 1)'),
-        'deps_neg': [ 'stdatomic', 'atomic-builtins' ],
     }, {
         'name': 'atomics',
         'desc': 'stdatomic.h support or emulation',
         'func': check_true,
         'req': True,
-        'deps_any': ['stdatomic', 'atomic-builtins', 'sync-builtins', 'gnuc'],
+        'deps_any': ['stdatomic', 'atomic-builtins', 'gnuc'],
     }, {
         'name': 'c11-tls',
         'desc': 'C11 TLS support',
-- 
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