From 39475179d40996b4efa662e3825735a84d2526d1 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 7 Dec 2009 12:52:05 +0100 Subject: [PATCH] [S390] Improve code generated by atomic operations. Git commit ea435467500612636f8f4fb639ff6e76b2496e4b changed the definition of atomic_t and atomic64_t for s390 by adding the volatile modifier to the counter field. This has an unfortunate side effect with newer versions of the gcc. The typeof operator now picks up the volatile modifier from the expression. This causes the compiler to think that it has to store the two temporary variable old_val and new_val in the __CS_LOOP for the different atomic operations to the stack as the variables are now volatile. Both stores are superfluous. The hack to replace typeof(ptr->counter) with int in __CS_LOOP and and long long in __CSG_LOOP avoids the two stores. A better solution would be to drop the volatile from the counter field of the atomic_t and atomic64_t definition. But that is a touchy subject .. Cc: Matthew Wilcox Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/atomic.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/s390/include/asm/atomic.h b/arch/s390/include/asm/atomic.h index ae7c8f9f94a5..2a113d6a7dfd 100644 --- a/arch/s390/include/asm/atomic.h +++ b/arch/s390/include/asm/atomic.h @@ -21,7 +21,7 @@ #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2) #define __CS_LOOP(ptr, op_val, op_string) ({ \ - typeof(ptr->counter) old_val, new_val; \ + int old_val, new_val; \ asm volatile( \ " l %0,%2\n" \ "0: lr %1,%0\n" \ @@ -38,7 +38,7 @@ #else /* __GNUC__ */ #define __CS_LOOP(ptr, op_val, op_string) ({ \ - typeof(ptr->counter) old_val, new_val; \ + int old_val, new_val; \ asm volatile( \ " l %0,0(%3)\n" \ "0: lr %1,%0\n" \ @@ -143,7 +143,7 @@ static inline int atomic_add_unless(atomic_t *v, int a, int u) #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2) #define __CSG_LOOP(ptr, op_val, op_string) ({ \ - typeof(ptr->counter) old_val, new_val; \ + long long old_val, new_val; \ asm volatile( \ " lg %0,%2\n" \ "0: lgr %1,%0\n" \ @@ -160,7 +160,7 @@ static inline int atomic_add_unless(atomic_t *v, int a, int u) #else /* __GNUC__ */ #define __CSG_LOOP(ptr, op_val, op_string) ({ \ - typeof(ptr->counter) old_val, new_val; \ + long long old_val, new_val; \ asm volatile( \ " lg %0,0(%3)\n" \ "0: lgr %1,%0\n" \ -- 2.20.1