RISC-V: Add slide to perm_const strategies.

This patch adds a shuffle_slide_patterns to expand_vec_perm_const.
It recognizes permutations like

  {0, 1, 4, 5}
or
  {2, 3, 6, 7}

which can be constructed by a slideup or slidedown of one of the vectors
into the other one.

gcc/ChangeLog:

	* config/riscv/riscv-v.cc (shuffle_slide_patterns): New.
	(expand_vec_perm_const_1): Call new function.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/vls-vlmax/shuffle-slide-run.c: New test.
	* gcc.target/riscv/rvv/autovec/vls-vlmax/shuffle-slide.c: New test.

0 files changed, 0 insertions, 0 deletions