Rotate instructions that complete execution either without writing or reading flags

A method comprising:

• storing a plurality of flags in a register, the plurality of flags including a carry flag, a sign flag, a zero flag, and an overflow flag;
• decoding instructions, including a single rotate right instruction, wherein some of the instructions indicate 64-bit general-purpose registers that store 64-bit operands in a 64-bit mode and store 32-bit operands in a 32-bit mode, wherein the 32-bit operands are stored in a lower 32-bits of the 64-bit general-purpose registers, and wherein the single rotate right instruction indicates a 64-bit operand size, a first 64-bit source operand, a second 64-bit source operand, and has a field specifying a first 64-bit general-purpose register;
• and
• performing operations corresponding to the single rotate right instruction, including:
• rotating the first 64-bit source operand right by an amount indicated by the second 64-bit source operand, wherein bits rotated out of a least significant bit of the first 64-bit source operand are rotated into a most significant bit of the first 64-bit source operand;
• storing a result including the first 64-bit source operand rotated right by the amount into the first 64-bit general-purpose register;
• and
• completing the execution of the decoded single rotate right instruction without reading the carry flag, without writing the carry flag, without reading the sign flag, without writing the sign flag, without reading the zero flag, without writing the zero flag, without reading the overflow flag, and without writing the overflow flag.

An apparatus comprising:

• a register to store a carry flag, an overflow flag, a sign flag, a zero flag, an auxiliary carry flag, a parity flag;
• a decoder operative to decode a rotate right instruction, the rotate right instruction to indicate a 64-bit source operand, to indicate a 64-bit general-purpose register, and having an immediate to indicate a rotate amount;
• and
• execution circuitry coupled with the decoder, the execution circuitry operative to perform operations corresponding to the rotate right instruction, including to:
• generate a result, the result to include the 64-bit source operand rotated by the rotate amount indicated by the immediate;
• store the result in the 64-bit general-purpose register;
• and
• complete execution of the rotate right instruction without causing the carry flag to be read, without causing the carry flag to be written, without causing the overflow flag to be read, without causing the overflow flag to be written, without causing the sign flag to be read, without causing the sign flag to be written, without causing the zero flag to be read, without causing the zero flag to be written, without causing the auxiliary carry flag to be read, without causing the auxiliary carry flag to be written, without causing the parity flag to be read, and without causing the parity flag to be written.