Hi! On Fri, Jul 23, 2021 at 04:23:42PM +0530, Prathamesh Kulkarni via Gcc wrote: > The constraint here is that, vshl_n<type> intrinsics require that the > second arg (__b), > should be an immediate value.
Something that matches the "n" constraint, not necessarily a literal, but stricter than just "immediate". It probably is a good idea to allow only "integer constant expression"s, so that the validity of the source code does not depend on what the optimisers do with the code. > As Richard suggested, sth like: > void foo(int x __attribute__((literal_constant (min_val, max_val))); The Linux kernel has a macro __is_constexpr to test if something is an integer constant expression, see <linux/const.h> . That is a much better idea imo. There could be a builtin for that of course, but an attribute is less powerful, less usable, less useful. Segher
