On Mon, Jan 06, 2025 at 12:21:39PM +0100, Morten Brørup wrote: > > From: Bruce Richardson [mailto:[email protected]] > > Sent: Monday, 6 January 2025 12.07 > > > > On Fri, Jan 03, 2025 at 12:39:38PM -0800, Andre Muezerie wrote: > > > __builtin_add_overflow is gcc specific. There's a need for a portable > > > version that can also be used with other compilers. > > > > > > This patch introduces rte_add_overflow. > > > > > > +/* > > > + * Function that allows performing simple arithmetic operations > > together with > > > + * checking whether the operation overflowed. > > > + * Example of usage: > > > + * uint8_t overflow; > > > + * uint16_t a, b, result; > > > + * a = 1; > > > + * b = 2; > > > + * overflow = rte_add_overflow(a, b, &result); > > > + */ > > > +#ifdef RTE_TOOLCHAIN_MSVC > > > +#define rte_add_overflow(a, b, res) _Generic((a), \ > > > + uint8_t : _addcarry_u8, \ > > > + uint16_t : _addcarry_u16, \ > > > + uint32_t : _addcarry_u32, \ > > > + uint64_t : _addcarry_u64)(0, a, b, res) > > > +#else > > > +#define rte_add_overflow(a, b, res) _Generic((a), \ > > > + uint8_t : __builtin_add_overflow, \ > > > + uint16_t : __builtin_add_overflow, \ > > > + uint32_t : __builtin_add_overflow, \ > > > + uint64_t : __builtin_add_overflow)(a, b, res) > > > +#endif > > > > For the gcc version, can you just simplify to the one-line below? > > > > #define rte_add_overflow __builtin_add_overflow > > Yes, but then GCC compilation would not fail if "a" has some other type than > the four types explicitly supported. > I prefer keeping the method used this v2 patch. > Is that really a problem? Should our DPDK macro not support all the types that the GCC builtin supports?
/Bruce
