diff options
Diffstat (limited to 'py/mpconfig.h')
| -rw-r--r-- | py/mpconfig.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/py/mpconfig.h b/py/mpconfig.h index f4b7c1058..45178034a 100644 --- a/py/mpconfig.h +++ b/py/mpconfig.h @@ -2336,4 +2336,23 @@ typedef time_t mp_timestamp_t; #define MP_WARN_CAT(x) (NULL) #endif +// If true, use __builtin_mul_overflow (a gcc intrinsic supported by clang) for +// overflow checking when multiplying two small ints. Otherwise, use a portable +// algorithm. +// +// Most MCUs have a 32x32->64 bit multiply instruction, in which case the +// intrinsic is likely to be faster and generate smaller code. The main exception is +// cortex-m0 with __ARM_ARCH_ISA_THUMB == 1. +// +// The intrinsic is in GCC starting with version 5. +#ifndef MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC +#if defined(__ARM_ARCH_ISA_THUMB) && (__GNUC__ >= 5) +#define MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC (__ARM_ARCH_ISA_THUMB >= 2) +#elif (__GNUC__ >= 5) +#define MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC (1) +#else +#define MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC (0) +#endif +#endif + #endif // MICROPY_INCLUDED_PY_MPCONFIG_H |