Homogenize memory barriers on atomics

Atomic operations with specified barriers have specified barrier semantics.
Set and read operations have undefined barrier semantics. All other atomic
operations implied full memory barriers, except when using the libatomic_ops
library and the tilera atomics api.

Some code in the runtime system assumed that all operations used (except for
set, read and specified) implied full memory barriers. The use of the
libatomic_ops library and the tilera atomics api have therefore been modified
to behave as the other implementations.

Some atomic operations with specified barrier semantics on sparc32 have also
been been relaxed in this commit.

1 files changed, 11 insertions, 15 deletions

diff --git a/erts/include/internal/libatomic_ops/ethr_atomic.h b/erts/include/internal/libatomic_ops/ethr_atomic.h
index d56693dbf8..2fc82c99a8 100644
--- a/erts/include/internal/libatomic_ops/ethr_atomic.h
+++ b/erts/include/internal/libatomic_ops/ethr_atomic.h
@@ -146,13 +146,13 @@ ETHR_NATMC_FUNC__(read)(ETHR_ATMC_T__ *var)
 static ETHR_INLINE ETHR_AINT_T__
 ETHR_NATMC_FUNC__(add_return)(ETHR_ATMC_T__ *var, ETHR_AINT_T__ incr)
 {
-#ifdef AO_HAVE_fetch_and_add
-    return ((ETHR_AINT_T__) AO_fetch_and_add(&var->counter, (AO_t) incr)) + incr;
+#ifdef AO_HAVE_fetch_and_add_full
+    return ((ETHR_AINT_T__) AO_fetch_and_add_full(&var->counter, (AO_t) incr)) + incr;
 #else
     while (1) {
 	AO_t exp = AO_load(&var->counter);
 	AO_t new = exp + (AO_t) incr;
-	if (AO_compare_and_swap(&var->counter, exp, new))
+	if (AO_compare_and_swap_full(&var->counter, exp, new))
 	    return (ETHR_AINT_T__) new;
     }
 #endif
@@ -167,8 +167,8 @@ ETHR_NATMC_FUNC__(add)(ETHR_ATMC_T__ *var, ETHR_AINT_T__ incr)
 static ETHR_INLINE ETHR_AINT_T__
 ETHR_NATMC_FUNC__(inc_return)(ETHR_ATMC_T__ *var)
 {
-#ifdef AO_HAVE_fetch_and_add1
-    return ((ETHR_AINT_T__) AO_fetch_and_add1(&var->counter)) + 1;
+#ifdef AO_HAVE_fetch_and_add1_full
+    return ((ETHR_AINT_T__) AO_fetch_and_add1_full(&var->counter)) + 1;
 #else
     return ETHR_NATMC_FUNC__(add_return)(var, 1);
 #endif
@@ -183,8 +183,8 @@ ETHR_NATMC_FUNC__(inc)(ETHR_ATMC_T__ *var)
 static ETHR_INLINE ETHR_AINT_T__
 ETHR_NATMC_FUNC__(dec_return)(ETHR_ATMC_T__ *var)
 {
-#ifdef AO_HAVE_fetch_and_sub1
-    return ((ETHR_AINT_T__) AO_fetch_and_sub1(&var->counter)) - 1;
+#ifdef AO_HAVE_fetch_and_sub1_full
+    return ((ETHR_AINT_T__) AO_fetch_and_sub1_full(&var->counter)) - 1;
 #else
     return ETHR_NATMC_FUNC__(add_return)(var, -1);
 #endif
@@ -202,7 +202,7 @@ ETHR_NATMC_FUNC__(and_retold)(ETHR_ATMC_T__ *var, ETHR_AINT_T__ mask)
     while (1) {
 	AO_t exp = AO_load(&var->counter);
 	AO_t new = exp & ((AO_t) mask);
-	if (AO_compare_and_swap(&var->counter, exp, new))
+	if (AO_compare_and_swap_full(&var->counter, exp, new))
 	    return (ETHR_AINT_T__) exp;
     }
 }
@@ -213,7 +213,7 @@ ETHR_NATMC_FUNC__(or_retold)(ETHR_ATMC_T__ *var, ETHR_AINT_T__ mask)
     while (1) {
 	AO_t exp = AO_load(&var->counter);
 	AO_t new = exp | ((AO_t) mask);
-	if (AO_compare_and_swap(&var->counter, exp, new))
+	if (AO_compare_and_swap_full(&var->counter, exp, new))
 	    return (ETHR_AINT_T__) exp;
     }
 }
@@ -225,7 +225,7 @@ ETHR_NATMC_FUNC__(cmpxchg)(ETHR_ATMC_T__ *var,
 {
     ETHR_AINT_T__ act;
     do {
-	if (AO_compare_and_swap(&var->counter, (AO_t) exp, (AO_t) new))
+	if (AO_compare_and_swap_full(&var->counter, (AO_t) exp, (AO_t) new))
 	    return exp;
 	act = (ETHR_AINT_T__) AO_load(&var->counter);
     } while (act == exp);
@@ -237,7 +237,7 @@ ETHR_NATMC_FUNC__(xchg)(ETHR_ATMC_T__ *var, ETHR_AINT_T__ new)
 {
     while (1) {
 	AO_t exp = AO_load(&var->counter);
-	if (AO_compare_and_swap(&var->counter, exp, (AO_t) new))
+	if (AO_compare_and_swap_full(&var->counter, exp, (AO_t) new))
 	    return (ETHR_AINT_T__) exp;
     }
 }
@@ -265,7 +265,6 @@ ETHR_NATMC_FUNC__(inc_return_acqb)(ETHR_ATMC_T__ *var)
     return ((ETHR_AINT_T__) AO_fetch_and_add1_acquire(&var->counter)) + 1;
 #else
     ETHR_AINT_T__ res = ETHR_NATMC_FUNC__(add_return)(var, 1);
-    ETHR_MEMORY_BARRIER;
     return res;
 #endif
 }
@@ -287,7 +286,6 @@ ETHR_NATMC_FUNC__(dec_return_relb)(ETHR_ATMC_T__ *var)
 #ifdef AO_HAVE_fetch_and_sub1_release
     return ((ETHR_AINT_T__) AO_fetch_and_sub1_release(&var->counter)) - 1;
 #else
-    ETHR_MEMORY_BARRIER;
     return ETHR_NATMC_FUNC__(dec_return)(var);
 #endif
 }
@@ -314,7 +312,6 @@ ETHR_NATMC_FUNC__(cmpxchg_acqb)(ETHR_ATMC_T__ *var,
     return act;
 #else
     ETHR_AINT_T__ act = ETHR_NATMC_FUNC__(cmpxchg)(var, new, exp);
-    ETHR_MEMORY_BARRIER;
     return act;
 #endif
 }
@@ -333,7 +330,6 @@ ETHR_NATMC_FUNC__(cmpxchg_relb)(ETHR_ATMC_T__ *var,
     } while (act == exp);
     return act;
 #else
-    ETHR_MEMORY_BARRIER;
     return ETHR_NATMC_FUNC__(cmpxchg)(var, new, exp);
 #endif
 }