RISC-V: Add sifive-7 pipeline description.

RISC-V: Add sifive-7 pipeline description.

	* config/riscv/generic.md (generic_alu, generic_load, generic_store)
	(generic_xfer, generic_branch, generic_imul, generic_idivsi)
	(generic_idivdi, generic_fmul_single, generic_fmul_double)
	(generic_fdiv, generic_fsqrt): Add check for generic tune.
	(generic_alu): Add auipc to type list.
	* config/riscv/riscv-opts.h (enum riscv_microarchitecture_type): New.
	(riscv_microarchitecture): Declare.
	* config/riscv/riscv-protos.h (riscv_store_data_bypass_p): Declare.
	* config/riscv/riscv.c (struct riscv_cpu_info): Add microarchitecture
	field.
	(riscv_microarchitecture): New.
	(sifive_7_tune_info): New.
	(riscv_cpu_info_table): Add microarchitecture value for rocket and
	size.  Add sifive-3-series, sifive-5-series, and sifive-7-series
	entries.
	(riscv_store_data_bypass_p): New.
	(riscv_option_override): Set riscv_microarchitecture from
	cpu->microarchitecture.
	* config/riscv/riscv.md: Include sifive-7.md.
	(type): Add auipc.
	(tune): New.
	(auipc<mode>): Change type to auipc.
	(restore_stack_nonlocal): New.
	* config/riscv/sifive-7.md: New.
	* doc/invoke.texi (RISC-V Options): Update mtune docs.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@269954 138bc75d-0d04-0410-961f-82ee72b054a4