eal: fix ARM build with clang

Use __atomic_exchange_n instead of __atomic_exchange_(2/4/8).

The error was:
	include/generic/rte_atomic.h:215:9: error:
		implicit declaration of function '__atomic_exchange_2'
		is invalid in C99
	include/generic/rte_atomic.h:494:9: error:
		implicit declaration of function '__atomic_exchange_4'
		is invalid in C99
	include/generic/rte_atomic.h:772:9: error:
		implicit declaration of function '__atomic_exchange_8'
		is invalid in C99

Fixes: ff2863570fcc ("eal: introduce atomic exchange operation")

Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>

diff --git a/lib/librte_eal/common/include/generic/rte_atomic.h b/lib/librte_eal/common/include/generic/rte_atomic.h
index 8652c02..b99ba46 100644 (file)
--- a/lib/librte_eal/common/include/generic/rte_atomic.h
+++ b/lib/librte_eal/common/include/generic/rte_atomic.h
@@ -212,7 +212,11 @@ rte_atomic16_exchange(volatile uint16_t *dst, uint16_t val);
 static inline uint16_t
 rte_atomic16_exchange(volatile uint16_t *dst, uint16_t val)
 {
+#if defined(RTE_ARCH_ARM64) && defined(RTE_TOOLCHAIN_CLANG)
+       return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
+#else
        return __atomic_exchange_2(dst, val, __ATOMIC_SEQ_CST);
+#endif
 }
 #endif
 
@@ -491,7 +495,11 @@ rte_atomic32_exchange(volatile uint32_t *dst, uint32_t val);
 static inline uint32_t
 rte_atomic32_exchange(volatile uint32_t *dst, uint32_t val)
 {
+#if defined(RTE_ARCH_ARM64) && defined(RTE_TOOLCHAIN_CLANG)
+       return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
+#else
        return __atomic_exchange_4(dst, val, __ATOMIC_SEQ_CST);
+#endif
 }
 #endif
 
@@ -769,7 +777,11 @@ rte_atomic64_exchange(volatile uint64_t *dst, uint64_t val);
 static inline uint64_t
 rte_atomic64_exchange(volatile uint64_t *dst, uint64_t val)
 {
+#if defined(RTE_ARCH_ARM64) && defined(RTE_TOOLCHAIN_CLANG)
+       return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
+#else
        return __atomic_exchange_8(dst, val, __ATOMIC_SEQ_CST);
+#endif
 }
 #endif