Imported Upstream version 6.10.0.49

Former-commit-id: 1d6753294b2993e1fbf92de9366bb9544db4189b

external/llvm-project/compiler-rt/lib/builtins/arm/sync_synchronize.S

@@ -0,0 +1,38 @@
+//===-- sync_synchronize - Implement memory barrier * ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "../assembly.h"
+
+//
+// When compiling a use of the gcc built-in __sync_synchronize() in thumb1 mode
+// the compiler may emit a call to __sync_synchronize.  
+// On Darwin the implementation jumps to an OS supplied function named 
+// OSMemoryBarrier
+//
+
+	.text
+	.syntax unified
+
+#if __APPLE__
+
+	.p2align 2
+DEFINE_COMPILERRT_PRIVATE_FUNCTION(__sync_synchronize)
+	stmfd	sp!, {r7, lr}
+	add		r7, sp, #0
+	bl		_OSMemoryBarrier
+	ldmfd	sp!, {r7, pc}
+END_COMPILERRT_FUNCTION(__sync_synchronize)
+
+	// tell linker it can break up file at label boundaries
+	.subsections_via_symbols
+		
+#endif
+
+NO_EXEC_STACK_DIRECTIVE
+