include/qemu/int128: Use Int128 structure for TCI

We are about to allow passing Int128 to/from tcg helper functions,
but libffi doesn't support __int128_t, so use the structure.

In order for atomic128.h to continue working, we must provide
a mechanism to frob between real __int128_t and the structure.
Provide a new union, Int128Alias, for this.  We cannot modify
Int128 itself, as any changed alignment would also break libffi.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 23 insertions, 6 deletions

diff --git a/include/qemu/atomic128.h b/include/qemu/atomic128.h
index adb9a1a260..d0ba0b9c65 100644
--- a/include/qemu/atomic128.h
+++ b/include/qemu/atomic128.h
@@ -44,13 +44,23 @@
 #if defined(CONFIG_ATOMIC128)
 static inline Int128 atomic16_cmpxchg(Int128 *ptr, Int128 cmp, Int128 new)
 {
-    return qatomic_cmpxchg__nocheck(ptr, cmp, new);
+    Int128Alias r, c, n;
+
+    c.s = cmp;
+    n.s = new;
+    r.i = qatomic_cmpxchg__nocheck((__int128_t *)ptr, c.i, n.i);
+    return r.s;
 }
 # define HAVE_CMPXCHG128 1
 #elif defined(CONFIG_CMPXCHG128)
 static inline Int128 atomic16_cmpxchg(Int128 *ptr, Int128 cmp, Int128 new)
 {
-    return __sync_val_compare_and_swap_16(ptr, cmp, new);
+    Int128Alias r, c, n;
+
+    c.s = cmp;
+    n.s = new;
+    r.i = __sync_val_compare_and_swap_16((__int128_t *)ptr, c.i, n.i);
+    return r.s;
 }
 # define HAVE_CMPXCHG128 1
 #elif defined(__aarch64__)
@@ -89,12 +99,18 @@ Int128 QEMU_ERROR("unsupported atomic")
 #if defined(CONFIG_ATOMIC128)
 static inline Int128 atomic16_read(Int128 *ptr)
 {
-    return qatomic_read__nocheck(ptr);
+    Int128Alias r;
+
+    r.i = qatomic_read__nocheck((__int128_t *)ptr);
+    return r.s;
 }
 
 static inline void atomic16_set(Int128 *ptr, Int128 val)
 {
-    qatomic_set__nocheck(ptr, val);
+    Int128Alias v;
+
+    v.s = val;
+    qatomic_set__nocheck((__int128_t *)ptr, v.i);
 }
 
 # define HAVE_ATOMIC128 1
@@ -132,7 +148,8 @@ static inline void atomic16_set(Int128 *ptr, Int128 val)
 static inline Int128 atomic16_read(Int128 *ptr)
 {
     /* Maybe replace 0 with 0, returning the old value.  */
-    return atomic16_cmpxchg(ptr, 0, 0);
+    Int128 z = int128_make64(0);
+    return atomic16_cmpxchg(ptr, z, z);
 }
 
 static inline void atomic16_set(Int128 *ptr, Int128 val)
@@ -141,7 +158,7 @@ static inline void atomic16_set(Int128 *ptr, Int128 val)
     do {
         cmp = old;
         old = atomic16_cmpxchg(ptr, cmp, val);
-    } while (old != cmp);
+    } while (int128_ne(old, cmp));
 }
 
 # define HAVE_ATOMIC128 1