Adaptive 128-bit floating point load and store operations for quadruple precision compatibility

摘要

A technique for providing adaptive 128-bit load and store operations to support architecture extensions for computations on a 128- bit quadruple precision format, in which a single set of load and store instructions provides for save and restore operations on both 80-bit and 128-bit floating point register files. A 128-bit load and store instructions are utilized for moving values that are 128-bit aligned in memory. The transfer entails the movement of data between a 128-bit memory boundary and a floating point register file for register save and restore operations. In one embodiment, 80-bit registers are used and in a second embodiment 128-bit registers are used. The same instructions operate on both the 80-bit and 128-bit registers to map the content of a given register into a 128-bit boundary field in memory. A load/store unit allocates the bit positioning so that when 80-bit registers are used, the 80 bits are moved into the most significant bit positions of the 128-bit boundary field. The remaining bit positions are filled with 0s. When values are moved to memory the reverse operation is performed.