[Bug target/82731] _mm256_set_epi8(array[offset[0]], array[offset[1]], ...) byte gather makes slow code, trying to zero-extend all the uint16_t offsets first and spilling them.

[liuhongt at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82731

--- Comment #7 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
(In reply to Hongtao Liu from comment #4)
> (In reply to Hongtao Liu from comment #3)
> > Looks like ix86_vect_estimate_reg_pressure doesn't work here, taking a look.
> 
> Oh, ix86_vect_estimate_reg_pressure is only for loop, BB vectorizer only use
> ix86_builtin_vectorization_cost, but not add_stmt_cost/finish_cost.

Oh, CTOR comes from source code, not from vectorizer.
Then why those loads from offset is not moved just before consumer(loads from
array), then the live range of those values can be shorten.(loads from array
are moved just before CTOR insns).