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MULX

Multiplies two unsigned operands and stores the result in two registers. The instruction performs an unsigned multiplication of two 64-bit operands, producing a 128-bit product.

The following table covers what the source and destinations can be:

DO NOT support LOCK

This instruction is available only in 64-bit mode. It SHALL NOT be used in compatibility mode.

Unlike the MUL instruction, MULX does NOT affect any flags in the RFLAGS register. Users MUST NOT rely on the Carry Flag (CF) or Overflow Flag (OF) to detect overflow of the 64-bit result, as these flags remain unchanged. Additionally, MULX does NOT use the implicit RAX register, allowing for non-destructive multiplication of operands.