riscv: thead: Add support for the XTheadBb ISA extension

riscv: thead: Add support for the XTheadBb ISA extension

This patch adds support for the XTheadBb ISA extension.
Thus, there is a functional overlap of the new instructions with
existing Bitmanip instruction, which allows a good amount of code
sharing. However, the vendor extensions are cleanly separated from
the standard extensions (e.g. by using INSN expand pattern that
will re-emit RTL that matches the patterns of either Bitmanip or
XThead INSNs).

gcc/ChangeLog:

	* config/riscv/bitmanip.md (clzdi2): New expand.
	(clzsi2): New expand.
	(ctz<mode>2): New expand.
	(popcount<mode>2): New expand.
	(<bitmanip_optab>si2): Rename INSN.
	(*<bitmanip_optab>si2): Hide INSN name.
	(<bitmanip_optab>di2): Rename INSN.
	(*<bitmanip_optab>di2): Hide INSN name.
	(rotrsi3): Remove INSN.
	(rotr<mode>3): Add expand.
	(*rotrsi3): New INSN.
	(rotrdi3): Rename INSN.
	(*rotrdi3): Hide INSN name.
	(rotrsi3_sext): Rename INSN.
	(*rotrsi3_sext): Hide INSN name.
	(bswap<mode>2): Remove INSN.
	(bswapdi2): Add expand.
	(bswapsi2): Add expand.
	(*bswap<mode>2): Hide INSN name.
	* config/riscv/riscv.cc (riscv_rtx_costs): Add costs for sign
	extraction.
	* config/riscv/riscv.md (extv<mode>): New expand.
	(extzv<mode>): New expand.
	* config/riscv/thead.md (*th_srri<mode>3): New INSN.
	(*th_ext<mode>): New INSN.
	(*th_extu<mode>): New INSN.
	(*th_clz<mode>2): New INSN.
	(*th_rev<mode>2): New INSN.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/xtheadbb-ext.c: New test.
	* gcc.target/riscv/xtheadbb-extu-2.c: New test.
	* gcc.target/riscv/xtheadbb-extu.c: New test.
	* gcc.target/riscv/xtheadbb-ff1.c: New test.
	* gcc.target/riscv/xtheadbb-rev.c: New test.
	* gcc.target/riscv/xtheadbb-srri.c: New test.

Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>