dcc

dcc is a primitive C compiler originally built as a capstone project for a graduate course in compilers at Cooper Union - ECE466, Prof. Jeff Hakner. dcc targets the entire C99 standard, with a subset of C99 features currently available.

You can compile a sizeable set of programs with dcc (but there's a lot of work to do to get to full C99). The target is x86-64 assembly.

Key info

• Written in C, lex, and yacc.

• Lexer, (LALR) parser, AST, symbol table, recursive descent quad generator, and linear assembly generator.

• Preprocessor and linker are provided by gcc or clang.

• Basic compilation process is described below -

  • The lexer reads and tokenizes preprocessed C input
  • The tokenized input and semantic values are consumed by the parser, spinning up an abstract syntax tree.
    • The symbol table is built at this time, maintaining a stack of lexical scopes (more symbol tables).
    • The AST links directly to symbol table entries.
  • The quad generator will descend the AST and produce a linear and externalizable IR.
  • The assembly generator consumes the quads/IR and produces x86 assembly.

More notes

• The generated code is bad. This should be a lightly optimizing compiler one day.
• The type engine needs a lot of investment.
• There is a fair amount of insanity.
• I don't try to leak memory, but I don't really try not to leak memory either.
• You can summon the oopsies mascot on purpose with the compiler internal

#pragma do-perish

• You can use #pragma do-examine yourvariablename and #pragma do-dumpsymtab to peek at symbols/symbol tables. These internals don't work at the start of a block (grammar needs tuning).
• There is a lot of cleanup to be done.
• Be gentle

Usage

• Dependencies: bison, flex, and requirements.txt.

• To build:

  $ scons dcc
  

• To use: (./dcc -h for usage)

  $ ./dcc yourprogram.c
  $ ./a.out
  

• To test:

  $ scons test
  

License

This project uses the MIT License.