Linting tools

Some of the tools used for design verification of ICs have their roots in software testing. Tools for software testing are sometimes characterized as static analysis and dynamic analysis tools. Static analysis tools evaluate software before it has run. 

An example of such a tool is Lint:It is not uncommon, when porting a software system to another host environment and recompiling all of the source code for the program, to experience a situation where source code that compiled without complaint on the original host now either refuses to compile or produces a long list of ominous sounding warnings during compilation. The fact is, no two compilers will check for exactly the same syntax and/or semantic violations. One compiler may attempt to interpret the programmer’s intention, while a second compiler may flag the error and refuse to generate an object module, and a third compiler may simply ignore the error.

Lint is a tool that examines C code and identifies such things as unused variables, variables that are used before being initialized, and argument mismatches. Commercial versions of Lint exist both for programming languages and for hardware design languages. A lint program attempts to discover all fatal and nonfatal errors in a program before it is executed. It then issues a list of warnings about code that could cause problems. Sometimes the programmer or logic designer is aware of the coding practice and does not consider it to be a problem. In such cases, a lint program will usually permit the user to mask out those messages so that more meaningful messages don’t become lost in a sea of detail.

In contrast to static analysis tools, dynamic analysis tools operate while the code is running. In software this code detects such things as memory leaks, bounds violations, null pointers, and pointers out of range. They can also identify source code that has been exercised and, more importantly, code that has not been exercised. Additionally, they can point out lines of code that have been exercised over only a partial range of their variables.