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Diffstat (limited to 'src/include/common/int.h')
| -rw-r--r-- | src/include/common/int.h | 437 |
1 files changed, 437 insertions, 0 deletions
diff --git a/src/include/common/int.h b/src/include/common/int.h new file mode 100644 index 0000000..a297221 --- /dev/null +++ b/src/include/common/int.h @@ -0,0 +1,437 @@ +/*------------------------------------------------------------------------- + * + * int.h + * Routines to perform integer math, while checking for overflows. + * + * The routines in this file are intended to be well defined C, without + * relying on compiler flags like -fwrapv. + * + * To reduce the overhead of these routines try to use compiler intrinsics + * where available. That's not that important for the 16, 32 bit cases, but + * the 64 bit cases can be considerably faster with intrinsics. In case no + * intrinsics are available 128 bit math is used where available. + * + * Copyright (c) 2017-2020, PostgreSQL Global Development Group + * + * src/include/common/int.h + * + *------------------------------------------------------------------------- + */ +#ifndef COMMON_INT_H +#define COMMON_INT_H + + +/*--------- + * The following guidelines apply to all the routines: + * - If a + b overflows, return true, otherwise store the result of a + b + * into *result. The content of *result is implementation defined in case of + * overflow. + * - If a - b overflows, return true, otherwise store the result of a - b + * into *result. The content of *result is implementation defined in case of + * overflow. + * - If a * b overflows, return true, otherwise store the result of a * b + * into *result. The content of *result is implementation defined in case of + * overflow. + *--------- + */ + +/*------------------------------------------------------------------------ + * Overflow routines for signed integers + *------------------------------------------------------------------------ + */ + +/* + * INT16 + */ +static inline bool +pg_add_s16_overflow(int16 a, int16 b, int16 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_add_overflow(a, b, result); +#else + int32 res = (int32) a + (int32) b; + + if (res > PG_INT16_MAX || res < PG_INT16_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int16) res; + return false; +#endif +} + +static inline bool +pg_sub_s16_overflow(int16 a, int16 b, int16 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_sub_overflow(a, b, result); +#else + int32 res = (int32) a - (int32) b; + + if (res > PG_INT16_MAX || res < PG_INT16_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int16) res; + return false; +#endif +} + +static inline bool +pg_mul_s16_overflow(int16 a, int16 b, int16 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_mul_overflow(a, b, result); +#else + int32 res = (int32) a * (int32) b; + + if (res > PG_INT16_MAX || res < PG_INT16_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int16) res; + return false; +#endif +} + +/* + * INT32 + */ +static inline bool +pg_add_s32_overflow(int32 a, int32 b, int32 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_add_overflow(a, b, result); +#else + int64 res = (int64) a + (int64) b; + + if (res > PG_INT32_MAX || res < PG_INT32_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int32) res; + return false; +#endif +} + +static inline bool +pg_sub_s32_overflow(int32 a, int32 b, int32 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_sub_overflow(a, b, result); +#else + int64 res = (int64) a - (int64) b; + + if (res > PG_INT32_MAX || res < PG_INT32_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int32) res; + return false; +#endif +} + +static inline bool +pg_mul_s32_overflow(int32 a, int32 b, int32 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_mul_overflow(a, b, result); +#else + int64 res = (int64) a * (int64) b; + + if (res > PG_INT32_MAX || res < PG_INT32_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int32) res; + return false; +#endif +} + +/* + * INT64 + */ +static inline bool +pg_add_s64_overflow(int64 a, int64 b, int64 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_add_overflow(a, b, result); +#elif defined(HAVE_INT128) + int128 res = (int128) a + (int128) b; + + if (res > PG_INT64_MAX || res < PG_INT64_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int64) res; + return false; +#else + if ((a > 0 && b > 0 && a > PG_INT64_MAX - b) || + (a < 0 && b < 0 && a < PG_INT64_MIN - b)) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = a + b; + return false; +#endif +} + +static inline bool +pg_sub_s64_overflow(int64 a, int64 b, int64 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_sub_overflow(a, b, result); +#elif defined(HAVE_INT128) + int128 res = (int128) a - (int128) b; + + if (res > PG_INT64_MAX || res < PG_INT64_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int64) res; + return false; +#else + if ((a < 0 && b > 0 && a < PG_INT64_MIN + b) || + (a > 0 && b < 0 && a > PG_INT64_MAX + b)) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = a - b; + return false; +#endif +} + +static inline bool +pg_mul_s64_overflow(int64 a, int64 b, int64 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_mul_overflow(a, b, result); +#elif defined(HAVE_INT128) + int128 res = (int128) a * (int128) b; + + if (res > PG_INT64_MAX || res < PG_INT64_MIN) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (int64) res; + return false; +#else + /* + * Overflow can only happen if at least one value is outside the range + * sqrt(min)..sqrt(max) so check that first as the division can be quite a + * bit more expensive than the multiplication. + * + * Multiplying by 0 or 1 can't overflow of course and checking for 0 + * separately avoids any risk of dividing by 0. Be careful about dividing + * INT_MIN by -1 also, note reversing the a and b to ensure we're always + * dividing it by a positive value. + * + */ + if ((a > PG_INT32_MAX || a < PG_INT32_MIN || + b > PG_INT32_MAX || b < PG_INT32_MIN) && + a != 0 && a != 1 && b != 0 && b != 1 && + ((a > 0 && b > 0 && a > PG_INT64_MAX / b) || + (a > 0 && b < 0 && b < PG_INT64_MIN / a) || + (a < 0 && b > 0 && a < PG_INT64_MIN / b) || + (a < 0 && b < 0 && a < PG_INT64_MAX / b))) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = a * b; + return false; +#endif +} + +/*------------------------------------------------------------------------ + * Overflow routines for unsigned integers + *------------------------------------------------------------------------ + */ + +/* + * UINT16 + */ +static inline bool +pg_add_u16_overflow(uint16 a, uint16 b, uint16 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_add_overflow(a, b, result); +#else + uint16 res = a + b; + + if (res < a) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = res; + return false; +#endif +} + +static inline bool +pg_sub_u16_overflow(uint16 a, uint16 b, uint16 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_sub_overflow(a, b, result); +#else + if (b > a) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = a - b; + return false; +#endif +} + +static inline bool +pg_mul_u16_overflow(uint16 a, uint16 b, uint16 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_mul_overflow(a, b, result); +#else + uint32 res = (uint32) a * (uint32) b; + + if (res > PG_UINT16_MAX) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (uint16) res; + return false; +#endif +} + +/* + * INT32 + */ +static inline bool +pg_add_u32_overflow(uint32 a, uint32 b, uint32 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_add_overflow(a, b, result); +#else + uint32 res = a + b; + + if (res < a) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = res; + return false; +#endif +} + +static inline bool +pg_sub_u32_overflow(uint32 a, uint32 b, uint32 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_sub_overflow(a, b, result); +#else + if (b > a) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = a - b; + return false; +#endif +} + +static inline bool +pg_mul_u32_overflow(uint32 a, uint32 b, uint32 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_mul_overflow(a, b, result); +#else + uint64 res = (uint64) a * (uint64) b; + + if (res > PG_UINT32_MAX) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (uint32) res; + return false; +#endif +} + +/* + * UINT64 + */ +static inline bool +pg_add_u64_overflow(uint64 a, uint64 b, uint64 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_add_overflow(a, b, result); +#else + uint64 res = a + b; + + if (res < a) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = res; + return false; +#endif +} + +static inline bool +pg_sub_u64_overflow(uint64 a, uint64 b, uint64 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_sub_overflow(a, b, result); +#else + if (b > a) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = a - b; + return false; +#endif +} + +static inline bool +pg_mul_u64_overflow(uint64 a, uint64 b, uint64 *result) +{ +#if defined(HAVE__BUILTIN_OP_OVERFLOW) + return __builtin_mul_overflow(a, b, result); +#elif defined(HAVE_INT128) + uint128 res = (uint128) a * (uint128) b; + + if (res > PG_UINT64_MAX) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = (uint64) res; + return false; +#else + uint64 res = a * b; + + if (a != 0 && b != res / a) + { + *result = 0x5EED; /* to avoid spurious warnings */ + return true; + } + *result = res; + return false; +#endif +} + +#endif /* COMMON_INT_H */ |