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index register

A second register in a memory operand that counts elements, multiplied by the element size before it is added.

An index register is added to the base after being scaled (x86-64 by 1, 2, 4 or 8; ARM64 by a left shift equal to the access size, or not at all); RISC-V has no indexed mode and adds the scaled index with separate instructions.

See also

scaled index memory operand
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