Design of the SubTiger Compiler (Without Tree IR)

The source code of the compiler is distributed across the following directories and files:

ir/
- ir.sml: Contains structure of the Intermediate Representation (IR)
- regAlloc.sml: Greedy register allocation
- translate.sml: Contains the code for translating the source of Tiger AST to the Intermediate Representation and the code for translating the Intermediate Representation to the assembly code
target/
- convToMIPS.sml: Contains helper functions to create MIPS assembly statements
- mips.sig and mips.sml: Signature and structure of the MIPS AST
- prettyMips.sml: Contains helper functions for the pretty printing of the MIPS assembly code
tiger/
- ast.sig and ast.sml: Signature and structure of the Tiger AST
- convToTiger.sml: Contains helper functions to create Tiger expressions
- prettyTigerAST.sml: Contains helper functions for the pretty printing of the Tiger expressions
- tiger.grm: Grammar of the Tiger language
- tiger.lex: Lexical analysis file
utils/
- env.sml: Structure to create an environment from user variable to temporaries
- temp.sml: Structure to create new temporary values and labels
- utils.sml: General purpose helper functions
tc.mlb: The ML-Basis file for compilation
tc.sml: The main code where the execution begins. This uses the lexer-parser, translator and pretty printers to generate MIPS assembly from the Tiger source code

Design Choices

We have used the following design choices:

Currently register allocation is implemented as a greedy register allocation and if the compiler runs out of registers just, it just flags an error
There are built-in functions for printing expression values, they are print and println which print the value without or with a newline respectively
The error checking mechanism is quite week as of now