RISC-V: Remove masking third operand of rotate instructions

RISC-V: Remove masking third operand of rotate instructions

    Rotate instructions do not need to mask the third operand.
    For example,  RV64 the following code:

    unsigned long foo1(unsigned long rs1, unsigned long rs2)
    {
        long shamt = rs2 & (64 - 1);
        return (rs1 << shamt) | (rs1 >> ((64 - shamt) & (64 - 1)));
    }

    Compiles to:
    foo1:
            andi    a1,a1,63
            rol     a0,a0,a1
            ret

    This patch removes unnecessary masking.
    Besides, I have merged masking insns for shifts that were written before.

gcc/ChangeLog:
	* config/riscv/riscv.md (*<optab><GPR:mode>3_mask): New pattern,
	combined from ...
	(*<optab>si3_mask, *<optab>di3_mask): Here.
	(*<optab>si3_mask_1, *<optab>di3_mask_1): And here.
	* config/riscv/bitmanip.md (*<bitmanip_optab><GPR:mode>3_mask): New
	pattern.
	(*<bitmanip_optab>si3_sext_mask): Likewise.
	* config/riscv/iterators.md (shiftm1): Use const_si_mask_operand
	and const_di_mask_operand.
	(bitmanip_rotate): New iterator.
	(bitmanip_optab): Add rotates.
	* config/riscv/predicates.md (const_si_mask_operand): Renamed
	from const31_operand.  Generalize to handle more mask constants.
	(const_di_mask_operand): Similarly.

gcc/testsuite/ChangeLog:
	* gcc.target/riscv/shift-and-2.c: Fixed test
	* gcc.target/riscv/zbb-rol-ror-01.c: New test
	* gcc.target/riscv/zbb-rol-ror-02.c: New test
	* gcc.target/riscv/zbb-rol-ror-03.c: New test
	* gcc.target/riscv/zbb-rol-ror-04.c: New test
	* gcc.target/riscv/zbb-rol-ror-05.c: New test
	* gcc.target/riscv/zbb-rol-ror-06.c: New test
	* gcc.target/riscv/zbb-rol-ror-07.c: New test