Merging single precision floating point operands

Where it is desired to perform a double precision operation using single precision operands, first and second single precision operands are loaded into first and second respective rows of a re-order buffer, and third and fourth single precision operands are loaded into third and fourth respective rows of the re-order buffer. A first merge instruction copies the first and second single precision operands from respective first and second rows of the re-order buffer into first and second portions of a fifth row of the re-order buffer, thereby concatenating the first and second single precision operands to represent a first double precision operand. A second merge instruction copies the third and fourth single precision operands from respective third and fourth rows of the re-order buffer into first and second portions of a sixth row of the re-order buffer, thereby concatenating the third and fourth single precision operands to represent a second double precision operand. The first and second double precision operands stored in the fifth and sixth rows, respectively, of the re-order buffer are then provided directly to an associated FPU for execution.