CompilerProject

MPCS 51300: Compilers

This project will give you the first building block of your own CSTR compiler. By the end of this project you will have a subset C-compiler generating the assembly code of your choice. As we saw during the first parts of this class, a compiler is divided into two main parts: the front-end and the back-end. In this initial project, we will tackle the first one. You will use the language/the library of your choice to create a scanner for the CSTR programming language. Your scanner will run through the source program, recognizing CSTR tokens. For each token, your scanner will return the right attributes and you will print the information on the stdout. An attribute can be an identifier name, a numerical value, a string, an operator, a symbol.

This project will give you the grammar that you will use for this compiler.

=============================================================================== System Requirement:

flex 2.5.39
bison 3.0.2
clang 3.6.2-1
llvm 3.6.2
Operating system is 64 bit

===============================================================================

Currently the Preprocessor and the Scanner are separate executables. They both take input from stdin and output to stdout. To run one into the other, just pipe the output from "preprocessor" into the input of "compiler".

$> ./bin/preprocessor < foo.c | ./bin/compiler >foo.ll

foo.ll is in LLVM assembly IR.

Notes about the Scanner implementation: 1) The Lexer has no notion of type, so when building the symbol table, it leaves that field blank.

=============================================================================== How to run LLVM

clang -S -emit-llvm sample.c -o sample.ll
opt-3.6 -S sample.ll
llc-3.6 -O3 sample.ll -march=x86-64 -o sample-x86-64.s
gcc sample-x86-64.s -o sample-x86-64
./sample-x86-64

opt-3.6 is to optimize the code.

If you want to try LLVM online, http://ellcc.org/demo/index.cgi.

Due to the different version of LLVM compilers, sample.ll will be different.

=============================================================================== To Do:

Print variables when printf is called. printf is a special function.
Assume all integers are %32.

===============================================================================

REFERENCES:

The usage pattern of Bison in this project (and also by extension Flex) is based on the example found at https://panthema.net/2007/flex-bison-cpp-example/.
Quick Start LLVM Tutorial at https://idea.popcount.org/2013-07-24-ir-is-better-than-assembly/.
Run LLVM Assembly in Brower at https://kripken.github.io/llvm.js/demo.html.
Implement a String Data Type in LLVM? at http://stackoverflow.com/questions/1061753/how-can-i-implement-a-string-data-type-in-llvm.
Local variables in LLVM IR at http://stackoverflow.com/questions/24605063/assigning-literal-value-to-local-variable-in-llvm-ir.
The Often Misunderstood GEP Instruction at http://llvm.org/docs/GetElementPtr.html#what-is-the-first-index-of-the-gep-instruction
L/R shift operations in C. logical vs arithmetic at http://stackoverflow.com/questions/7622/shift-operator-in-c Based on the discussion on this page, we chose to implement them as arithmetic shifts. (The test file "test/test_cases/rsh.c" doesn't seem to test for one or the other though.)
Reference for colored output in bash script. at http://stackoverflow.com/questions/5947742/how-to-change-the-output-color-of-echo-in-linux

yiqin/CompilerProject

CompilerProject