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meson: Split test for __int128_t type from __int128_t arithmetic

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Older versions of clang have missing runtime functions for arithmetic
with -fsanitize=undefined (see 464e3671f9), so we cannot use
__int128_t for implementing Int128.  But __int128_t is present,
data movement works, and it can be used for atomic128.

Probe for both CONFIG_INT128_TYPE and CONFIG_INT128, adjust
qemu/int128.h to define Int128Alias if CONFIG_INT128_TYPE,
and adjust the meson probe for atomics to use has_int128_type.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-05-24 08:14:41 -07:00
parent 9e0e6a7e8e
commit 6479dd74f1
2 changed files with 12 additions and 7 deletions
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4
include/qemu/int128.h
View File

@ -481,7 +481,7 @@ static inline void bswap128s(Int128 *s)
* a possible structure and the native types. Ease parameter passing
* via use of the transparent union extension.
*/
#ifdef CONFIG_INT128
#ifdef CONFIG_INT128_TYPE
typedef union {
__uint128_t u;
__int128_t i;
@ -489,6 +489,6 @@ typedef union {
} Int128Alias __attribute__((transparent_union));
#else
typedef Int128 Int128Alias;
#endif /* CONFIG_INT128 */
#endif /* CONFIG_INT128_TYPE */
#endif /* INT128_H */

15
meson.build
View File

@ -2543,7 +2543,13 @@ config_host_data.set('CONFIG_ATOMIC64', cc.links('''
return 0;
}'''))
has_int128 = cc.links('''
has_int128_type = cc.compiles('''
__int128_t a;
__uint128_t b;
int main(void) { b = a; }''')
config_host_data.set('CONFIG_INT128_TYPE', has_int128_type)
has_int128 = has_int128_type and cc.links('''
__int128_t a;
__uint128_t b;
int main (void) {
@ -2552,10 +2558,9 @@ has_int128 = cc.links('''
a = a * a;
return 0;
}''')
config_host_data.set('CONFIG_INT128', has_int128)
if has_int128
if has_int128_type
# "do we have 128-bit atomics which are handled inline and specifically not
# via libatomic". The reason we can't use libatomic is documented in the
# comment starting "GCC is a house divided" in include/qemu/atomic128.h.
@ -2564,7 +2569,7 @@ if has_int128
# __alignof(unsigned __int128) for the host.
atomic_test_128 = '''
int main(int ac, char **av) {
unsigned __int128 *p = __builtin_assume_aligned(av[ac - 1], 16);
__uint128_t *p = __builtin_assume_aligned(av[ac - 1], 16);
p[1] = __atomic_load_n(&p[0], __ATOMIC_RELAXED);
__atomic_store_n(&p[2], p[3], __ATOMIC_RELAXED);
__atomic_compare_exchange_n(&p[4], &p[5], p[6], 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED);
@ -2586,7 +2591,7 @@ if has_int128
config_host_data.set('CONFIG_CMPXCHG128', cc.links('''
int main(void)
{
unsigned __int128 x = 0, y = 0;
__uint128_t x = 0, y = 0;
__sync_val_compare_and_swap_16(&x, y, x);
return 0;
}