Satyam Sharma wrote:
From: Satyam Sharma <[email protected]>
[6/8] i386: bitops: Don't mark memory as clobbered unnecessarily
The goal is to let gcc generate good, beautiful, optimized code.
But test_and_set_bit, test_and_clear_bit, __test_and_change_bit,
and test_and_change_bit unnecessarily mark all of memory as clobbered,
thereby preventing gcc from doing perfectly valid optimizations.
The case of __test_and_change_bit() is particularly surprising, given
that it's a variant where we don't make any guarantees at all.
__test_and_change_bit is one that you could remove the memory clobber
from.
---
include/asm-i386/bitops.h | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/asm-i386/bitops.h b/include/asm-i386/bitops.h
index 0f5634b..f37b8a2 100644
--- a/include/asm-i386/bitops.h
+++ b/include/asm-i386/bitops.h
@@ -254,7 +254,7 @@ static inline int __test_and_change_bit(int nr, unsigned long *addr)
__asm__ __volatile__(
"btcl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (*addr)
- :"r" (nr) : "memory");
+ :"r" (nr));
return oldbit;
}
--
SUSE Labs, Novell Inc.
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