I appreciate the effort to have a web page talking about writing your own compiler. Right now, I'm looking for an easy way to add define-use chains to a compiler. I know it involves breaking code into blocks and tracing through the code looking for use of the same variables. This tutorial is good because it adds a symbol table on each block level, which helps in differentiating names that are re-used in a block and don't refer to other variables of the same name. Does anyone know of code that makes clear what is involved in def-use for a variable without saying "this is an exercise for the reader" ?
> a symbol table on each block level, which helps in differentiating names
Yes, that's something that every compiler (for languages with scopes that allow hiding) needs. Typically you also never compare variables by name but by pointer to a symbol structure or some numeric ID.
> Does anyone know of code that makes clear what is involved in def-use for a variable without saying "this is an exercise for the reader" ?
It's not code, but chapter 2 of Nielson/Nielson/Hankin's Principles of Program Analysis discusses how to do this. See accompanying slides on the book's website: http://www.imm.dtu.dk/~hrni/PPA/ppasup2004.html
In a sense, this must be an exercise for the reader, since if you are working on your own compiler, nobody's code will be compatible with yours.
Go has several packages supporting program analysis in the standard library. https://golang.org/pkg/go/types/#Info populates separate maps for Defs and Uses. Check out the source for how they walk the SSA and calculate def-use chains.
