hjc

The Haskell MiniJava Compiler build at the LMU course "Compiler Construction"

How to use

> git clone https://github.com/cirquit/hjc
> cd hjc
> stack build && stack install
> hjc --help
hjc - A MiniJava Compiler in Haskell

Usage: hjc javaFile [--showAst] [-t|--showTime] [--canonCmm] [-c|--compileToCmm]
           [-w|--compileToX86] [-g|--createIFGraph] [--javaOutputDir javaDir]
           [--cmmOutputDir cmmDir] [--x86OutputDir x86Dir]
           [--cfOutputDir graphDir]
           [-e|--typeErrLvl [AllErrors|Silently|FirstError]]
           [-x|--compileToAllocatedX86] [--showJava] [-s|--inSequence]

Available options:
  --showAst                show Ast
  -t,--showTime            show Time
  --canonCmm               canonize Cmm
  -c,--compileToCmm        compile to Cmm
  -w,--compileToX86        compile to X86 Code
  -g,--createIFGraph       create Control Flow Graph
  --javaOutputDir javaDir  directory of java files
  --cmmOutputDir cmmDir    directory of cmm files
  --x86OutputDir x86Dir    directory of x86 assembly files
  --cfOutputDir graphDir   directory of control flow graph
  -e,--typeErrLvl [AllErrors|Silently|FirstError]
                           defines which level of errors should bee shown
  -x,--compileToAllocatedX86
                           compile to allocated X86 Code
  --showJava               show the recreated java output
  -s,--inSequence          run the computation sequential
  -h,--help                Show this help text

Features

• definition + declaration is allowed

int x = 1;

• if and else may be in a single line without braces

if (boolean_value) do_something();
else do_something_else();

• parens in expressions allowed

(1 + 2) * 3  // returns 6

• the register allocation is in parallel, by sharing the fresh variables in a an IORef. This is on by default and can be removed by the flag -n

• we support multiple level instruction removal by not used nodes in the graph and mov's to unused temps

• we initialize every variable with 0 by default, so code like this is allowed

int x = 2;
int y;
int z = y + x; // 2

• we created a simple DSL for working with the x86 assembly code, which supports comments for intermediate representation

...
     DIV_C   -> do 
         mov eax op1  # "moving first arg to eax for idiv"
         t <- nextTempO 
         mov t op2
         cdq
         idiv t
         mov op1 eax  # "move idiv result to initial destination"
...

• we have a nice command line interface, which is extendable and can configure almost every switch in this compiler

• we've written our own parser with megaparsec and could therefore create nice error messages (unfortunately, colors are not visible here)

> hjc examples/Arg.java
>> Starting to lex examples/Arg.java
>> examples/Arg.java:8:18: error:

  unexpected tokens: [Tokens ('{' :| "")]
    expected tokens: [Tokens ('(' :| ""),Tokens ('_' :| ""),Label ('a' :| "lphanumeric character")]

...
       public int go{int i} {
...
                   ^^^
  failed parsing.
>> Finished in: 120.0ms
--------------------------------------------------------------------------------

• the same goes for the typechecking (with different error levels, configurable via flags)

> hjc examples/Arg.java
>> Starting to lex examples/Arg.java
>> Typechecking failed: 

        Terminating with 3 typeerrors.

   #1 class A : method go:
        identifier "j" is undefined and thus has no type

   #2 class A : method go:
        type  "Object" does not match expected types "int" in expression:

         j

   #3 class A : method go:
        operator  /  is not defined for type "Object", allowed types are "int"

• we also have a full testsuite on every automatically testable property of the steps in between

How to compile to binary and run

Compile with hjc <filename>.java. This will create a x86output folder for you, then you have to link it yourself. In this project structure, the folder already has a Makefile which can be used by make file=<filename>-allocated.s.

How to use the C-- Backend

Compile to name.tree with a configurable flag -c and --canonCmm. Install the tree2c tool:

> git clone https://gitlab.cip.ifi.lmu.de/schoepp/Compilerbau17
> cd src/tree2c
> stack build
> stack install

Check if you have libc6-dev-i386 or g++-multilib or libc6-dev-i386 package installed. In my case, this only worked with clang-3.8.

> cd cmm-output
> tree2c <name>-cmm.tree > <name>.c
> gcc -m32 <name>.c runtime.c -o <name>
> ./name

Otherwise, in the cmm-output folder, there is a prepared Makefile, which can be run by make file=Add-canonized.tree.

Graph visualization

Install the graphviz program - sudo apt-get install graphviz. Set the config flag --createIFGraph. To show the graph as PostScript file:

> cd if-graph-output
> dot -Tps ProgramName.dot -o output.ps

Otherwise, in the if-graph-out folder, there is a prepared Makefile, which can be run by make file=Arg.dot.

Development

This project is using stack-1.3.2.

Styleguide

Using hindent-5.2.1. Install with stack install --resolver nightly-2016-10-17 hindent.

Testing

• Run tests (in the main folder of the repository)

stack test

• Run a specific test file i.e.

stack test --test-arguments "-m "TypeCheck/TypeCheck""

• Fail fast

stack test --test-arguments "--fail-fast"

• Run a specific test file, fail fast and filewatch

stack test --file-watch --test-arguments "-m "TypeCheck/TypeCheck" --fail-fast"

• Errors

  • 111: IndexOutOfBounds

• Debug with gdb

> gdb ./testprog

>>> tui enable  -- enables a terminal ui
>>> refresh     -- redraws the tui

>>> b Lmain     -- set breakpoint at function Lmain
>>> n           -- next
>>> print var   -- shows var
>>> backtrace   -- shows stacktrace
>>> quit