Codemorphing: Fresh as a DAISY

There's more than one way to guarantee software compatibility between X86-based software and very long instruction word processors.

Transmeta -- which made its codemorphing software the centrepiece of its low-power chips -- has developed one approach to insuring compatibility. IBM Research, with its Dynamically Architected Instruction Set from Yorktown (DAISY) translator, is building another.

Last month, the very long instruction word (VLIW) project at IBM's TJ Watson Research Centre released DAISY into open source, under the IBM open source licence. The DAISY dynamic compiler work is an offshoot of IBM'S VLIW initiative, which began in 1986.

For its part, Transmeta has said it plans to release an updated version of its codemorphing software in the first quarter of 2001.

Transmeta's codemorphing software is designed to provide software compatibility between existing Intel X86-based software applications and its own Crusoe instruction set, which provides for parallel processing and, therefore, higher performance. Transmeta claims that the code-morphing software "continuously learns about and re-optimises software applications a user is running to improve power usage and performance".

By providing that compatibility in software, rather than hardware, Transmeta says Crusoe can rely on a simpler hardware design that has been optimised for lower power consumption. Transmeta has trademarked the term "codemorphing".

IBM Research's DAISY also is aimed at providing compatibility between X86 software and IBM's VLIW processors. But, according to IBM, DAISY also will provide compatibility between PowerPC, S/390, IBM's Java Virtual Machine and VLIW, and "other novel [instruction-level parallelism] ILP architectures".

Calls to both IBM and Transmeta, requesting comment on how their VLIW-translation strategies differ, were not returned prior to publication.

But one commentator, posting on the open source enthusiast site Slashdot.org, attempted to explain the differences this way: "According to their white paper, Transmeta uses dynamic binary translation to convert x86 code into code for Transmeta's internal architecture. This is similar in concept to the current version of DAISY which converts PowerPC code into code for an underlying DAISY VLIW machine."

The poster, Scott Dier, continued: "DAISY was developed at IBM independently of Transmeta. The DAISY research project focuses less on low power and more on achieving instruction level parallelism in a server environment and on convergence of different architectures on a common microprocessor core. A more detailed comparison of the DAISY and Transmeta approaches will be possible after Transmeta publishes their techniques in more detail."

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