Symbol Table

• SymbolTable

  The main class used for storing all the necessary info about classes and inheritance

• Class

  Represents a defined class
  Keeps info about the variables and functions of the class

• Function

  Represents a defined function
  Keeps info about the arguments the function takes and the variables declared in it

• Variable

  Represents a defined variable

In order to print the offsets in the required order, order of decleration is important and a LinkedHashMap is used (instead of a simple HashMap)

Visitors

• PopulatingVisitor

  Populates the symbol table while performing minor semantic analysis, through the symbol table itself, in cases where an error is identifed throws an Exception
  For example catches the case where a class extend a not yet defined one and if a class/variable/function is redefined on the same scope

• AnalysisVisitor

  Performs the semantic analysis
  When a semantic error occurs throws an Exception

• IRVisitor

  Performs the LLVM code generation
  Requires the other two visitors to have already executed

Representation of arrays on LLVM code produced

• Integer arrays

  Integer arrays are represented with the type structure type { i32, i32* }
  The non pointer is where the size is stored
  The pointer points to the actuall array

• Boolean arrays

  Boolean arrays are represented with the type structure type { i32, i1* }
  The non pointer is where the size is stored
  The pointer points to the actuall array

It was implemented this way to perform the required out of bounds checks and to not waste any much memory

Changes on the code of the previous assignment

• Added a vtable field on each class, which is a map of <Function name, Class Name> and some helper functions
• The creation of the vtable for all the classes is performed while the PopulatingVisitor is executing.
  When a new class is created it "inherits" the vtable of the class it extends (if it does)
  For every new function added, if it already exists on the vtable change its Class name to the current function and if it doesn't just add it.
  This way we can easily manage the vtables on the IRVisitor

Compilation and Execution

While on folder src run

• make compile to generate the files needed
• java Main <file1> ... <fileN> to perform semantic analysis on files
• make clean to remove the generated files
• make run to do all of the above

Testing

While on folder src run the following commands to perform different tests

• ./test_many.bash <MiniJava1> ... <MiniJavaN>
  Test the functionality of java [MainClassName] [file1] [file2] ... [fileN] on the given files

• ./test_offsets.bash <path to offset.txt dir> <path to MiniJava.java dir>
  Number of arguments can be 0, 1 or 2
  0 arguments -> default paths
  1 argument -> path for directory containing the offset.txt files (files with the expected results)
  2 arguments -> first argument same as above, second argument path for the directory with the inpout MiniJava files

• ./test_sc.bash <path to MiniJava.java dir>
  Performs semantic analysis on all the .java files of the given directory (defualt one if none is given)
  Stops if it encounters an unexpected behavior (eg an error occured/didn't occur when it shouldn't have/should have occured)

• ./test_llvm.bash <path to outputs.out dir>
  For every .out file of the fiven directory (defualt one if none is given), produces the .ll and .out (through clang) files for the corresponding .java files of the same folder and check if it matches the original (correct) .out file given
  Stops if the produced output is wrong