Targeting a Processor and Extensions Support Overview

This section describes targeting a processor and processor dispatch options, the feature for IA-32 only. The options -tpp{5|6|7} optimizes for the IA-32 processors, and the options  -x{i|M|K|W} and -ax{i|M|K|W} provide support to generate code that is specific to processor-instruction extensions.

-tpp{5|6|7}

-tpp5—PentiumŪ processor.
-tpp6—Pentium Pro, Pentium II, and Pentium III processors. Default.
-tpp7—Pentium 4 processor. Requires the RedHat version 6.2 and support of Streaming SIMD Extensions 2.

-x{i|M|K|W}

Generates specialized code to run exclusively on the processors supporting the extensions indicated by the i, M, K, W codes.

-ax{i|M|K|W}

Generates specialized code to run exclusively on the processors supporting the extensions indicated by the i, M, K, W codes while also generating generic IA-32 code.

For example, on PentiumŪ III processor, if you have mostly integer code and only a small portion of floating-point code, you may want to compile with -axM rather than -axK because MMX(TM) technology extensions perform the best with the integer data.

The -ax and -x options are backward compatible with the extensions supported. On IntelŪ PentiumŪ 4 processor, you can gear your code to any of the previous processors specified by K, M, or i