vget_lane_p64 triggers -Wvector-conversion diagnostic

[llvmbot]

Bugzilla Link	48257
Version	11.0
OS	Windows NT
Reporter	LLVM Bugzilla Contributor
CC	@topperc,@c-rhodes,@DMG862,@fhahn,@zygoloid,@sjoerdmeijer

Extended Description

vget_lane_p64 is defined in arm_neon.h as:

#define vget_lane_p64(__p0, __p1) extension ({
poly64x1_t __s0 = __p0;
poly64_t __ret;
__ret = (poly64_t) __builtin_neon_vget_lane_i64((poly64x1_t)__s0, __p1);
__ret;
})

Note the cast on the first argument to __builtin_neon_vget_lane_i64; vget_lane_i64 takes an int64x1_t, not a poly64x1_t, so code which calls this macro ends up emitting a -Wvector-conversion diagnostic:

error: incompatible vector types passing 'poly64x1_t' (vector of 1 'poly64_t' value) to parameter of type 'attribute((vector_size(1 * sizeof(long)))) long' (vector of 1 'long' value) [-Werror,-Wvector-conversion]

For an example, you can use:

#include <arm_neon.h>

poly64_t foo (poly64x1_t v);

poly64_t
foo (poly64x1_t v) {
return vget_lane_p64(v, 0);
}

Or, on Compiler Explorer: https://godbolt.org/z/GWf6fq

It looks like this is a problem on all the vget*_lane_p64 functions.

[mr-c]

I can confirm this bug still exists as of clang 16 and clang trunk by using the provided Compiler Explorer link