Decaf is a small Java-like language for education purpose. This repository implements new features of λ-expressions, based on the original branch. Apart from MIPS-backend, it also compiles to JVM.
To build this project, you need JDK 14 (NOTE: the original branch was developed under JDK 12).
Other dependencies will be automatically downloaded from the maven central repository by the build script.
Type standard sbt commands after you launch the REPL with sbt.
To compile, type:
sbt:decaf-in-scala> compile
To build a standalone jar, type:
sbt:decaf-in-scala> assembly
To start a scala REPL, type:
sbt:decaf-in-scala> console
Or, import the project in IDEA and use sbt plugin, if available.
In sbt console, type:
sbt:decaf-in-scala> run --help
to show the usage help. Or you first build a standalone jar and run it in CLI.
Possible targets/tasks are:
- PA1: parse source code and output the pretty printed tree, or error messages
- PA2: type check and output the pretty printed scopes, or error messages
- PA3: generate TAC (three-address code), dump it to a .tac file, and then output the execution result using our built-in simulator
- PA3-JVM: generate JVM bytecode
- PA4: currently same with PA3, will be reserved for students to do a bunch of optimizations on TAC
- PA5: (default target) allocate registers and emit assembly code, currently we are using a very brute-force algorithm and only generates MIPS assembly code (with pseudo-ops, and no delayed branches)
To run the MIPS assembly code, you may need spim, a MIPS32 simulator.
For Mac OS users, simply install spim with brew install spim and run with spim -file your_file.s.
The demo/ folder contains a little testcase with new features. For example, to compile this to JVM:
cd demo/
mkdir out/
java -jar ../target/decaf.jar demo/demo.decaf -t PA3-JVM -d out
cd out/
java Main
You may use Java disassembly tools to inspect the bytecode generated for this testcase, e.g.
javap -v -p Foo
javap -v -p Main
For more testcases with the new λ-expression feature, see here.