AN720 データシートの表示（PDF） - Silicon Laboratories

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AN720

PRECISION32 OPTIMIZATIONCONSIDERATIONS FOR CODESIZE ANDSPEED

Silicon Laboratories 

AN720

5.5. Toolchain Optimization Settings

In addition to the library types, each toolchain has multiple optimization settings that can affect the resulting code

size. With the Precision32 toolchain, code optimization can be set by following these steps:

1. Right-click on the project_name in the Project Explorer view.

2. Select Properties.

3. In the C/C++ BuildSettingsTool Settings tabMCU C CompilerOptimization options, select

the desired optimization level.

Figure 5 shows the optimization settings for the Precision32 IDE. Level -O0 has the least optimization, while -O3

has the most optimization. An additional flag (-Os) allows for specific optimization for code size.

More information on the optimization levels can be found on the Code Red website (http://support.code-red-

tech.com/CodeRedWiki/CompilerOptimization) and the GCC website (http://gcc.gnu.org/onlinedocs/gcc-4.0.4/gcc/

Optimize-Options.html). Declaring a variable as volatile will prevent the compiler from optimizing out the variable.

Figure 5. Setting the Project Optimization in the Precision32 IDE

The Precision32 IDE has two build configurations by default: Debug and Release. These build configurations have

predefined optimization levels (None for Debug, -O2 for Release). To switch between the two configurations:

1. Right-click on the project_name in the Project Explorer view.

2. Select Build ConfigurationsSet Active and select between Debug and Release.

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