Projects of the Group on DSP Tools

DSP Compiler and Processor Evaluation - DSPstone

How good are Compilers for DSP-architectures ?

The difference between theses two implementations is measured in terms of code-size and execution time. This was done for several architectures in order to gain information about the abilities of the compilers to address certain features of the architecture.

Having a look at the Analog Devices DSP we clearly see that the handwritten assembly code almost outperforms the code produced by the compiler. The execution of the compiler generated code takes 8 times longer than the one written by hand. The code size also is significantly larger. This means if you develop your application with such a compiler you'll have to take a much faster DSP, spend more money for external memory. As a result nearly all time-critical applications are implemented by hand. Some of the reasons why DSP-Compilers are so bad are:

• unability to use machine idioms (MAC-operation)
• unability to make use of certain architectural features (zero overhead loops)
• unability to make use of possible instruction level parallelism