AN720 View Datasheet(PDF) - Silicon Laboratories

Part Name

Description

MFG CO.

AN720

PRECISION32 OPTIMIZATIONCONSIDERATIONS FOR CODESIZE ANDSPEED

Silicon Laboratories 

AN720

6.5. Toolchain Optimization Settings

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

size. In Keil µVision, the optimization settings are set using the following steps:

1. Right-click on the project_name in the Project window and select Options for Target ‘project_name’ or

go to ProjectOptions for Target ‘project_name’.

2. Select the C/C++ tab.

3. Use the Optimization drop-down menu to set the project optimization setting.

Figure 11 shows the optimization settings in the IDE.

The available options are:

Level 0: minimum optimization

Level 1: restricted optimization, removing inline functions and unused static functions

Level 2: high optimization

Level 3: maximum optimization with aims to produce faster code or smaller code size than Level 2,

depending on the options used

In addition to the levels, µVision also has an Optimize for Time selection available below the Optimization drop-

down menu. Declaring a variable as volatile will prevent the compiler from optimizing out the variable.

More information on these optimization levels can be found on the Keil website (http://www.keil.com/support/man/

docs/uv4/uv4_dg_adscc.htm).

Figure 11. Setting the Project Optimization in the µVision IDE

Using the sim3u1xx_Blinky and demo_si32UsbAudio default examples in the si32HAL 1.0.1 software package,

Table 21 and Table 22 show the relative Debug build sizes with the different optimization level settings. Table 23

shows the CoreMark Debug build sizes, and Table 24 lists the CoreMark speed scores for these optimization

levels.

22

Rev. 0.1

Share Link: