Backport 2002-03-22 fix from newer linuxthreads versions defining

MEMORY_BARRIER() as a asm op which clobbers memory to avoid unintended
reordering by the compiler.

1 files changed, 21 insertions, 0 deletions

diff --git a/devel/linuxthreads/files/patch-barrier b/devel/linuxthreads/files/patch-barrier
new file mode 100644
index 000000000000..f60402d634c0
--- /dev/null
+++ b/devel/linuxthreads/files/patch-barrier
@@ -0,0 +1,21 @@
+--- internals.h.orig	Tue May 16 00:23:50 2006
++++ internals.h	Tue May 16 00:24:21 2006
+@@ -395,12 +395,14 @@
+ #endif
+ }
+ 
+-/* If MEMORY_BARRIER isn't defined in pt-machine.h, assume the architecture
+-   doesn't need a memory barrier instruction (e.g. Intel x86).  Some
+-   architectures distinguish between full, read and write barriers.  */
++/* If MEMORY_BARRIER isn't defined in pt-machine.h, assume the
++   architecture doesn't need a memory barrier instruction (e.g. Intel
++   x86).  Still we need the compiler to respect the barrier and emit
++   all outstanding operations which modify memory.  Some architectures
++   distinguish between full, read and write barriers.  */
+ 
+ #ifndef MEMORY_BARRIER
+-#define MEMORY_BARRIER()
++#define MEMORY_BARRIER() asm ("" : : : "memory")
+ #endif
+ #ifndef READ_MEMORY_BARRIER
+ #define READ_MEMORY_BARRIER() MEMORY_BARRIER()