diff options
Diffstat (limited to 'crypto/bn/rsa_sup_mul.c')
| -rw-r--r-- | crypto/bn/rsa_sup_mul.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/crypto/bn/rsa_sup_mul.c b/crypto/bn/rsa_sup_mul.c index 0e0d02e194..3b57161b45 100644 --- a/crypto/bn/rsa_sup_mul.c +++ b/crypto/bn/rsa_sup_mul.c @@ -110,12 +110,34 @@ static ossl_inline void _mul_limb(limb_t *hi, limb_t *lo, limb_t a, limb_t b) *lo = (limb_t)t; } #elif (BN_BYTES == 8) && (defined _MSC_VER) -/* https://learn.microsoft.com/en-us/cpp/intrinsics/umul128?view=msvc-170 */ +# if defined(_M_X64) +/* + * on x86_64 (x64) we can use the _umul128 intrinsic to get one `mul` + * instruction to get both high and low 64 bits of the multiplication. + * https://learn.microsoft.com/en-us/cpp/intrinsics/umul128?view=msvc-140 + */ +#include <intrin.h> #pragma intrinsic(_umul128) static ossl_inline void _mul_limb(limb_t *hi, limb_t *lo, limb_t a, limb_t b) { *lo = _umul128(a, b, hi); } +# elif defined(_M_ARM64) || defined (_M_IA64) +/* + * We can't use the __umulh() on x86_64 as then msvc generates two `mul` + * instructions; so use this more portable intrinsic on platforms that + * don't support _umul128 (like aarch64 (ARM64) or ia64) + * https://learn.microsoft.com/en-us/cpp/intrinsics/umulh?view=msvc-140 + */ +#include <intrin.h> +static ossl_inline void _mul_limb(limb_t *hi, limb_t *lo, limb_t a, limb_t b) +{ + *lo = a * b; + *hi = __umulh(a, b); +} +# else +# error Only x64, ARM64 and IA64 supported. +# endif /* defined(_M_X64) */ #else /* * if the compiler doesn't have either a 128bit data type nor a "return |