LoongArch: Implement vec_init<M><N> where N is a LSX vector mode
This patch implements more vec_init optabs that can handle two LSX vectors producing a LASX
vector by concatenating them. When an lsx vector is concatenated with an LSX const_vector of
zeroes, the vec_concatz pattern can be used effectively. For example as below
typedef short v8hi __attribute__ ((vector_size (16)));
typedef short v16hi __attribute__ ((vector_size (32)));
v8hi a, b;
* config/loongarch/lasx.md (vec_initv32qiv16qi): Rename to ..
(vec_init<mode><lasxhalf>): .. this, and extend to mode.
(@vec_concatz<mode>): New insn pattern.
* config/loongarch/loongarch.cc (loongarch_expand_vector_group_init):
Handle VALS containing two vectors.
gcc/testsuite/ChangeLog:
* gcc.target/loongarch/vector/lasx/lasx-vec-init-2.c: New test.