Visual Instruction Set

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Visual Instruction Set, or VIS, is a SIMD instruction set extension for SPARC V9 microprocessors developed by Sun Microsystems. There are five versions of VIS: VIS 1, VIS 2, VIS 2+, VIS 3 and VIS 4. [1]

Contents

History

VIS 1 was introduced in 1994 and was first implemented by Sun in their UltraSPARC microprocessor (1995) and by Fujitsu in their SPARC64 GP microprocessors (2000).

VIS 2 was first implemented by the UltraSPARC III. All subsequent UltraSPARC and SPARC64 microprocessors implement the instruction set.

VIS 3 was first implemented in the SPARC T4 microprocessor.

VIS 4 was first implemented in the SPARC M7 microprocessor.

Differences vs x86

VIS is not an instruction toolkit like Intel's MMX and SSE. MMX has only 8 registers shared with the FPU stack, while SPARC processors have 32 registers, also aliased to the double-precision (64-bit) floating point registers.

As with the SIMD instruction set extensions on other RISC processors, VIS strictly conforms to the main principle of RISC: keep the instruction set concise and efficient.

This design is very different from comparable extensions on CISC processors, such as MMX, SSE, SSE2, SSE3, SSE4, 3DNow!.

Sometimes, programmers must use several VIS instructions to accomplish an operation that can be done with only one MMX or SSE instruction, but it should be kept in mind that fewer instructions do not automatically result in better performance.

Functionality

VIS re-uses existing SPARC V9 64-bit floating point registers to hold multiple 8, 16, or 32-bit integer values. In this respect, VIS is more similar to the design of MMX than other SIMD architectures such as SSE/SSE2/AltiVec.

VIS includes a number of operations primarily for graphics support, so most of them are only for integers. These include 3D to 2D conversion, edge processing and pixel distance.

There are four ways to use VIS in code:

Related Research Articles

x86 Family of instruction set architectures

x86 is a family of instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introduced in 1978 as a fully 16-bit extension of Intel's 8-bit 8080 microprocessor, with memory segmentation as a solution for addressing more memory than can be covered by a plain 16-bit address. The term "x86" came into being because the names of several successors to Intel's 8086 processor end in "86", including the 80186, 80286, 80386 and 80486 processors.

SPARC

SPARC is a reduced instruction set computing (RISC) instruction set architecture (ISA) originally developed by Sun Microsystems. Its design was strongly influenced by the experimental Berkeley RISC system developed in the early 1980s. First developed in 1986 and released in 1987, SPARC was one of the most successful early commercial RISC systems, and its success led to the introduction of similar RISC designs from a number of vendors through the 1980s and 90s.

SIMD

Single instruction, multiple data (SIMD) is a class of parallel computers in Flynn's taxonomy. It describes computers with multiple processing elements that perform the same operation on multiple data points simultaneously. Such machines exploit data level parallelism, but not concurrency: there are simultaneous (parallel) computations, but only a single process (instruction) at a given moment. SIMD is particularly applicable to common tasks such as adjusting the contrast in a digital image or adjusting the volume of digital audio. Most modern CPU designs include SIMD instructions to improve the performance of multimedia use. SIMD is not to be confused with SIMT, which utilizes threads.

AltiVec is a single-precision floating point and integer SIMD instruction set designed and owned by Apple, IBM, and Freescale Semiconductor — the AIM alliance. It is implemented on versions of the PowerPC processor architecture, including Motorola's G4, IBM's G5 and POWER6 processors, and P.A. Semi's PWRficient PA6T. AltiVec is a trademark owned solely by Freescale, so the system is also referred to as Velocity Engine by Apple and VMX by IBM and P.A. Semi.

MMX (instruction set)

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In computing, Streaming SIMD Extensions (SSE) is a single instruction, multiple data (SIMD) instruction set extension to the x86 architecture, designed by Intel and introduced in 1999 in their Pentium III series of Central processing units (CPUs) shortly after the appearance of Advanced Micro Devices (AMD's) 3DNow!. SSE contains 70 new instructions, most of which work on single precision floating-point data. SIMD instructions can greatly increase performance when exactly the same operations are to be performed on multiple data objects. Typical applications are digital signal processing and graphics processing.

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UltraSPARC

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References

  1. Liang He; Harlan McGhan (May 2005). "MT mediaLib for Chip MultiThreaded (CMT) Processors" (PDF). Sun Microsystems, Inc. Archived from the original (PDF) on December 30, 2006. Retrieved 2007-12-03.