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authorRickard Green <[email protected]>2016-02-17 16:56:05 +0100
committerRickard Green <[email protected]>2016-02-18 16:10:31 +0100
commiteb59e961ae05048ea30362aafb7f91db26ceb939 (patch)
treea95909e1a97d5ff7f4b3b3a5ea9f1d28bb5b4c4c /erts/include/internal/i386/ethr_dw_atomic.h
parent661aeed3ef57de87330123adf6100e179fd7dad0 (diff)
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Improve cmpxchg8b/cmpxchg16b inline asm
Clang didn't like that ecx/rcx was mapped to input and output variables of different types.
Diffstat (limited to 'erts/include/internal/i386/ethr_dw_atomic.h')
-rw-r--r--erts/include/internal/i386/ethr_dw_atomic.h57
1 files changed, 37 insertions, 20 deletions
diff --git a/erts/include/internal/i386/ethr_dw_atomic.h b/erts/include/internal/i386/ethr_dw_atomic.h
index 79de5d80da..5444a6345c 100644
--- a/erts/include/internal/i386/ethr_dw_atomic.h
+++ b/erts/include/internal/i386/ethr_dw_atomic.h
@@ -157,36 +157,53 @@ ethr_native_dw_atomic_cmpxchg_mb(ethr_native_dw_atomic_t *var,
ETHR_DW_DBG_ALIGNED__(p);
+#if ETHR_NO_CLOBBER_EBX__ && ETHR_CMPXCHG8B_REGISTER_SHORTAGE
+ /*
+ * gcc wont let us use ebx as input and we
+ * get a register shortage
+ */
+
__asm__ __volatile__(
-#if ETHR_NO_CLOBBER_EBX__
"pushl %%ebx\n\t"
-# if ETHR_CMPXCHG8B_REGISTER_SHORTAGE
"movl (%7), %%ebx\n\t"
"movl 4(%7), %%ecx\n\t"
-# else
- "movl %8, %%ebx\n\t"
-# endif
-#endif
- "lock; cmpxchg" ETHR_DW_CMPXCHG_SFX__ " %0\n\t"
+ "lock; cmpxchg8b %0\n\t"
"setz %3\n\t"
-#if ETHR_NO_CLOBBER_EBX__
"popl %%ebx\n\t"
-#endif
: "=m"(*p), "=d"(xchg[1]), "=a"(xchg[0]), "=c"(xchgd)
- : "m"(*p), "1"(xchg[1]), "2"(xchg[0]),
-#if ETHR_NO_CLOBBER_EBX__
-# if ETHR_CMPXCHG8B_REGISTER_SHORTAGE
- "3"(new)
-# else
- "3"(new[1]),
- "r"(new[0])
-# endif
+ : "m"(*p), "1"(xchg[1]), "2"(xchg[0]), "r"(new)
+ : "cc", "memory");
+
+#elif ETHR_NO_CLOBBER_EBX__
+ /*
+ * gcc wont let us use ebx as input
+ */
+
+ __asm__ __volatile__(
+ "pushl %%ebx\n\t"
+ "movl %8, %%ebx\n\t"
+ "lock; cmpxchg8b %0\n\t"
+ "setz %3\n\t"
+ "popl %%ebx\n\t"
+ : "=m"(*p), "=d"(xchg[1]), "=a"(xchg[0]), "=q"(xchgd)
+ : "m"(*p), "1"(xchg[1]), "2"(xchg[0]), "c"(new[1]), "r"(new[0])
+ : "cc", "memory");
+
#else
- "3"(new[1]),
- "b"(new[0])
-#endif
+ /*
+ * gcc lets us place values in the registers where
+ * we want them
+ */
+
+ __asm__ __volatile__(
+ "lock; cmpxchg" ETHR_DW_CMPXCHG_SFX__ " %0\n\t"
+ "setz %3\n\t"
+ : "=m"(*p), "=d"(xchg[1]), "=a"(xchg[0]), "=q"(xchgd)
+ : "m"(*p), "1"(xchg[1]), "2"(xchg[0]), "c"(new[1]), "b"(new[0])
: "cc", "memory");
+#endif
+
return (int) xchgd;
}