Author: Armin Rigo <ar...@tunes.org>
Branch: c7
Changeset: r710:f59e497a6ec5
Date: 2014-02-07 20:24 +0100
http://bitbucket.org/pypy/stmgc/changeset/f59e497a6ec5/
Log: Use __sync_synchronize() as a general fall-back. Update comments.
diff --git a/c7/core.h b/c7/core.h
--- a/c7/core.h
+++ b/c7/core.h
@@ -199,14 +199,18 @@
static inline void write_fence(void)
{
+ /* This function inserts a "write fence". The goal is to make
+ sure that past writes are really pushed to memory before
+ the future writes. We assume that the corresponding "read
+ fence" effect is done automatically by a corresponding
+ __sync_bool_compare_and_swap(). */
#if defined(__amd64__) || defined(__i386__)
- /* this is only a compiler barrier
- use __sync_synchronize(...) or other __sync_OPs that
- are locked by the CPU if you need to prevent
- loads to be moved before stores to different locations */
+ /* this is only a compiler barrier, which is enough on x86 */
asm("" : : : "memory");
#else
-# error "Define write_fence() for your architecture"
+ /* general fall-back, but we might have more efficient
+ alternative on some other platforms too */
+ __sync_synchronize();
#endif
}
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