MDK优化等级设置

原文地址http://www.keil.com/support/man/docs/armccref/armccref_cihgfgfb.htm

摘抄日期2013-08

原文
0     Minimum optimization. Turns off most optimizations.It gives the best possible debug view and the lowest level of optimization.            近乎不优化，用于调试代码。出现代码行不能设置断点可如此设置试试。
1          Restrictedoptimization. Removes unused inline functions and unused static functions.Turns off optimizations that seriously degrade the debug view. Ifused with --debug, this option gives a satisfactorydebug view with good code density.

部分优化。移除未调用的内联函数和静态函数，关闭debug窗口优化，此状态也能用于调试

2          Highoptimization. If used with --debug, the debug viewmight be less satisfactory because the mapping of object code tosource code is not always clear.

This is the default optimization level.

            默认优化等级。如果处于debug状态，部分代码行将不能被调试，具体做了什么优化好像没说
3     Maximumoptimization. -O3 performs the same optimizationsas -O2 however the balance between space and timeoptimizations in the generated code is more heavily weighted towardsspace or time compared with -O2. That is:

• -O3 -Otime aims to produce fastercode than -O2 -Otime, at the risk of increasingyour image size

• -O3 -Ospace aims to produce smallercode than -O2 -Ospace, but performance might bedegraded.

In addition, -O3 performs extra optimizationsthat are more aggressive, such as:

• High-levelscalar optimizations, including loop unrolling, for -O3 -Otime. Thiscan give significant performance benefits at a small code size cost,but at the risk of a longer build time.

• More aggressive inlining and automatic inliningfor -O3 -Otime.

楼主很懒不想译了。

这关方的解释不是很明朗。期待老手来解释。