Pushes the contents of a 64-bit register onto the stack.

    Format

      $PUSH64  reg

1  –  Parameters

 reg

    Register to be pushed onto the stack.

2  –  Description

    $PUSH64 takes a 64-bit register and puts it on the stack
    using longword instructions. This is to avoid using quadword
    instructions when an alignment fault should be avoided, but
    saving all 64 bits is necessary.