A simple multi-pass compiler that transforms an arithmetic s-expression language to a subset of x86 assembly.
Siek describes a compilation model for the R1 language that uses a series of sequential passes. These passes incrementally transform the initial R1 s-expression to x860 assembly via a C0 intermediate representation.
Under Siek’s guidence, the following steps are prescribed.
r1 --------uniquify--------->
r1 --remove-complex-opera*-->
r1 ----explicate-control---->
c0 -----uncover-locals------>
c0 ---select-instructions--->
x860* ----assign-homes------>
x860* ------patch-inst------>
x860 -------print-x86------->
Test modules for several of these steps leverage a behaviorally equivilant R1 interpreter defined in r1/interp.rkt. A C0 interpreter is also included that is useful for testing transformations to this intermediate representation.
Top level functionality is not yet implementated. This project remains under development.
Much of the compiler’s functionality involves symbol generation, so equality testing might require definition of an s-expression equality operator that uses pattern-matching to ignore symbols.
To avoid such a distraction, a property-based approach is used instead: Transformations, while changing sematics, should preserve evaluation result. Therefore, interpreting a program before and after a transformation should evaluate to the same value.
On this basis, tests simply loop through a set of programs defined in test/test-programs.rkt, checking that interpreting the program before and after the transformation under test yields the same value.
With a suitable R1 (or C0) program generator, programs may instead be generated at test time and the examples can be migrated to documentation.
For now, tests should be run on a per-module basis. All tests are included as sub-modules paired with relevant functionality.
Use raco to evoke tests from the command-line:
raco test interp.rkt # third arg is name of file with tests