Naive Pascal Compiler

A naïve Pascal compiler for the course Compiler Principle at ZJU. In summary, it adopts Flex and Bison at the front end, and uses LLVM as the back end.

Features

• Simple Data Types: boolean, char, integer, real
  • string literals are also supported
• Control Flow Statements: if-else, case-of, while-do, repeat-until, and for loops
• Definition Sections: const, type, var, and routine sections
• Routine (function and procedure) definition and invocation
  • including built-in routines: read(ln), write(ln), abs, sqrt, chr, ord, pred, succ
• Operators: + - * / div mod and or xor not and comparison operators
• Type Checking, and Implicit Conversion from integer to real
• Case Insensitivity as per the Pascal standard

Usage

USAGE: npc <option> <input.pas>
OPTION:
  -emit-llvm    Emit LLVM assembly code (.ll)
  -S            Emit assembly code (.s)
  -c            Emit object code (.o)
  -O            (Optional) do optimization

One of three emission options should be specified. The output file will be generated under the same directory as the input file.

• For LLVM assembly files, run lli output.ll to directly execute them.
• For assembly and object files, run cc output.{s,o} to generate executables.

Dependencies

• CMake 3.7+
• Flex 2.5+
• Bison 3.0+
• LLVM 5.0+

TODO

• refactor header dependencies
• add more practical test programs
• explicitly fix shift/reduce conflict of if-else
• generate detailed error messages for Flex/Bison
• do error recovery in Bison and codegen
• support all built-in functions and procedures
• support complex data types (string, array, record, set)
• support var parameters
• handle nested routines correctly