This patch skips execution of memtransfer/memset if there actually isn't
anything to do. Calls to memcpy/memmove/memset with size==0 should be
rare I'd suppose but prior code would still treat this no-op like some
store (ml_wt was particularly bad: it would to acquire _all_ locks in
such a case due to calculating a correct exclusive upper bound anymore).
OK for trunk?
4.7 too?
commit e0cd0b0a1cac087020d63e63e2d8ff67eab915d1
Author: Torvald Riegel <trie...@redhat.com>
Date: Mon Mar 5 14:27:01 2012 +0100
libitm: Don't execute memtransfer/memset if size isn't larger than zero.
libitm/
* dispatch.h (CREATE_DISPATCH_METHODS_MEM): Don't execute
memtransfer/memset if size isn't larger than zero.
diff --git a/libitm/dispatch.h b/libitm/dispatch.h
index d059c49..6a9e62e 100644
--- a/libitm/dispatch.h
+++ b/libitm/dispatch.h
@@ -102,11 +102,13 @@
virtual void memtransfer(void *dst, const void* src, size_t size, \
bool may_overlap, ls_modifier dst_mod, ls_modifier src_mod) \
{ \
- memtransfer_static(dst, src, size, may_overlap, dst_mod, src_mod); \
+ if (size > 0) \
+ memtransfer_static(dst, src, size, may_overlap, dst_mod, src_mod); \
} \
virtual void memset(void *dst, int c, size_t size, ls_modifier mod) \
{ \
- memset_static(dst, c, size, mod); \
+ if (size > 0) \
+ memset_static(dst, c, size, mod); \
}
#define CREATE_DISPATCH_METHODS_MEM_PV() \
