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Diffstat (limited to 'src/nvim/assert.h')
| -rw-r--r-- | src/nvim/assert.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/nvim/assert.h b/src/nvim/assert.h index 761636305e..29195a49dc 100644 --- a/src/nvim/assert.h +++ b/src/nvim/assert.h @@ -121,4 +121,34 @@ ((enum { ASSERT_CONCAT(assert_line_, __LINE__) = 1/(!!(e)) }) 0) #endif +/// @def STRICT_ADD +/// @brief Adds (a + b) and stores result in `c`. Aborts on overflow. +/// +/// Requires GCC 5+ and Clang 3.8+ +/// https://clang.llvm.org/docs/LanguageExtensions.html +/// https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html +/// +/// Alternative for compilers without __builtin_xx_overflow ? +/// https://stackoverflow.com/a/44830670/152142 +/// +/// @param MAX Maximum value of the narrowest type of operand. +/// Not used if compiler supports __builtin_add_overflow. +#if HAVE_BUILTIN_ADD_OVERFLOW +# define STRICT_ADD(a, b, c, t) \ + do { if (__builtin_add_overflow(a, b, c)) { abort(); } } while (0) +#else +# define STRICT_ADD(a, b, c, t) \ + do { *(c) = (t)(a + b); } while (0) +#endif + +/// @def STRICT_SUB +/// @brief Subtracts (a - b) and stores result in `c`. Aborts on overflow. +#if HAVE_BUILTIN_ADD_OVERFLOW +# define STRICT_SUB(a, b, c, t) \ + do { if (__builtin_sub_overflow(a, b, c)) { abort(); } } while (0) +#else +# define STRICT_SUB(a, b, c, t) \ + do { *(c) = (t)(a - b); } while (0) +#endif + #endif // NVIM_ASSERT_H |