compilers-course

Practical part of the compilers course (2017)

Common tasks and tests

The common tasks are tested with JUnit Parameterized tests generated from anlun/comiler-tests, see FileTestCases.kt. There's also a pack of my own tests in the same source set.

Implementation details

To precisely track boxed and unboxed values, the x86 back-end stores each value along with its kind (which is either scalar or reference). The value kind is also passed to and returned from functions (the intrinsics show this in their signatures) along with the value. A type is returned from a function in the ebx register.

Memory management is done through reference counting. There's a memory stress test here: arrayMemoryStressTest.

Personal task – Java-like exceptions

Check the ExceptionTestCases.kt. The following is supported:

• throw (E e) statement where E is an identifier for an exception type, and e is the exception data

• try <...> catch (E1 e1) <...> catch (E2 e2) <...> finally <...> yrt statement with optional catch and finally blocks

The semantics are derived from Java, in particular:

• the finally block is always triggered when the control flow leaves the try block or its catch blocks (indcluding return statements);

• throwing an exception from a try or catch goes through the finally block as well;

• throwing an exception from a finally block replaces the currently uncaught exception with a new one (no suppressed exceptions for now);

The implementation tracks exit points within the scopes and compiles them into if-else-if-like catch blocks. The exception type is returned by writing to the caller's stack frame (the value is returned normally).