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. See the summary of options supporting Targeting a Processor and Extensions Support.
-tpp{5|6|7} |
-tpp5 |
-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 and Xeon processors, you can gear your code to any of the previous processors specified by K, M, or i.