mariadb/extra/crc32-vpmsum/clang_workaround.h
Tulio Magno Quites Machado Filho 9aacda409d MDEV-21984: POWER crc32 acceleration - fix clang's behavior on versions >= 7
Clang 7 changed the behavior of vec_xxpermdi in order to match GCC's
behavior.  After this change, code that used to work on Clang 6 stopped
to work on Clang >= 7.

Tested on Clang 6, 7, 8 and 9.

Reference: https://bugs.llvm.org/show_bug.cgi?id=38192

Upstream fix: 361aaf77a5
2020-04-13 14:32:10 +03:00

87 lines
2.3 KiB
C

#ifndef CLANG_WORKAROUNDS_H
#define CLANG_WORKAROUNDS_H
/*
* These stubs fix clang incompatibilities with GCC builtins.
*/
#ifndef __builtin_crypto_vpmsumw
#define __builtin_crypto_vpmsumw __builtin_crypto_vpmsumb
#endif
#ifndef __builtin_crypto_vpmsumd
#define __builtin_crypto_vpmsumd __builtin_crypto_vpmsumb
#endif
static inline
__vector unsigned long long __attribute__((overloadable))
vec_ld(int __a, const __vector unsigned long long* __b)
{
return (__vector unsigned long long)__builtin_altivec_lvx(__a, __b);
}
/*
* GCC __builtin_pack_vector_int128 returns a vector __int128_t but Clang
* does not recognize this type. On GCC this builtin is translated to a
* xxpermdi instruction that only moves the registers __a, __b instead generates
* a load.
*
* Clang has vec_xxpermdi intrinsics. It was implemented in 4.0.0.
*/
static inline
__vector unsigned long long __builtin_pack_vector (unsigned long __a,
unsigned long __b)
{
#if defined(__BIG_ENDIAN__)
__vector unsigned long long __v = {__a, __b};
#else
__vector unsigned long long __v = {__b, __a};
#endif
return __v;
}
/*
* Clang 7 changed the behavior of vec_xxpermdi in order to provide the same
* behavior of GCC. That means code adapted to Clang >= 7 does not work on
* Clang <= 6. So, fallback to __builtin_unpack_vector() on Clang <= 6.
*/
#if !defined vec_xxpermdi || __clang_major__ <= 6
static inline
unsigned long __builtin_unpack_vector (__vector unsigned long long __v,
int __o)
{
return __v[__o];
}
#if defined(__BIG_ENDIAN__)
#define __builtin_unpack_vector_0(a) __builtin_unpack_vector ((a), 0)
#define __builtin_unpack_vector_1(a) __builtin_unpack_vector ((a), 1)
#else
#define __builtin_unpack_vector_0(a) __builtin_unpack_vector ((a), 1)
#define __builtin_unpack_vector_1(a) __builtin_unpack_vector ((a), 0)
#endif
#else
static inline
unsigned long __builtin_unpack_vector_0 (__vector unsigned long long __v)
{
#if defined(__BIG_ENDIAN__)
return vec_xxpermdi(__v, __v, 0x0)[0];
#else
return vec_xxpermdi(__v, __v, 0x3)[0];
#endif
}
static inline
unsigned long __builtin_unpack_vector_1 (__vector unsigned long long __v)
{
#if defined(__BIG_ENDIAN__)
return vec_xxpermdi(__v, __v, 0x3)[0];
#else
return vec_xxpermdi(__v, __v, 0x0)[0];
#endif
}
#endif /* vec_xxpermdi */
#endif