TASKING VX-toolset for ARM User Guide

Using the C Compilercompiled.This is a natural result of global optimizations, where the code generated for multiple moduleswas affected by the change.In general, if you do not need code compaction, for example because you are optimizing fully for speed,it is recommended to choose Optimize less/Build faster.Optimization OptionsIn general any optimization may require more work to be done by the compiler. But this does not meanthat disabling all optimizations (level 0) gives the fastest compilation time. Disabling optimizations mayresult in more code being generated, resulting in more work for other parts of the compiler, like for examplethe register allocator.Automatic InliningAutomatic inlining is an optimization which can result in significant longer build time. The overall functionswill get bigger, often making it possible to do more optimizations. But also often resulting in more registersto be in use in a function, giving the register allocation a tougher job.Code CompactionWhen you disable the code compaction optimization, the build times may be shorter. Certainly when MILlinking is used where the full application is passed as a single MIL stream to the code generation. Codecompaction is however an optimization which can make a huge difference when optimizing for code size.When size matters it makes no sense to disable this option. When you choose to optimize for speed(--tradeoff=0) the code compaction is automatically disabled.Compiler CacheThe C compiler has support for caching intermediate results to avoid full compilations. When the sourcecode after preprocessing and relevant compiler options and the compiler version are the same as in aprevious invocation, the previous result is copied to the output file. The cache only works when there isa single C input file and a single output file (no --mil-split).To enable caching from Eclipse:1. From the Project menu, select Properties forThe Properties dialog appears.2. In the left pane, expand C/C++ Build and select Settings.In the right pane the Settings appear.3. On the Tool Settings tab, select C/C++ Compiler » Optimization » Compilation Speed.4. Enable the option Cache generated code to improve the compilation speed.5. In the Directory for cached files field, enter the name for the location of the cache.By default this is the .cache directory under your project directory.161