Yet-Another-Grace-Compiler

Authors
Giorgos Kosmas (@gkosm314)
Apostolis Stamatis (@apostolis1)

Prerequisites

The project was developed using llvm-12.

Building

make builds the gracec executable and the libgrc.a file.

make clean deletes all automatically generated files except the gracec executable.

make distclean same as make clean but also deletes the gracec executable.

Testing

An extensive testing suite is developed to assure

Tests are available in the /tests directory and are organized in the following way:

• lexical: testing lexer
• optimizations: testing optimization passes
• parser: testing parser
• scope: testing scopes
• type_checking: testing types
• runtime: testing code generation
• runtime/leetcode: leetcode problems solved in grace
• runtime/repo: tests from the NTUA compilers repo
• runtime/unit: unit tests

The convention used in the naming of tests is that if a filename begins with err (e.g. /tests/parser/err_arr_def_expr.grc) the compilation should not be successfull.

A utility script is provided in tests/run_tests.sh to automatically run the test suite (make sure you change the directory path at the beginning of a file)

Using the gracec compiler

The gracec executable can be used to produce intermediate and final code

The following flags are supported:

-o: Make optimizations

-i Read input from stdin and dump intermediate code to stdout

-f Read input from stdin and dump final code to stdout

If neither -i nor -f are set, the source code is read from a file, the path of which is the only argument passed to gracec. In that case, the intermediate code is place to a .imm file in the same path as the source code file. Same goes about the final code which is placed in a .asm file. For example, running ./gracec /tmp/buy_and_sell_stock.grc will produce the files: /tmp/buy_and_sell_stock.imm and /tmp/buy_and_sell_stock.asm

Setting both the -i and -f flags is not supported, since the output would consist of both intermediate and final code, making it confusing to read.

The final code can then be compiled to an executable by a compiler like clang. Note that in this case a file containing the library calls should be linked, eg libgrc.a.

Additionally, the intermediate code can be compiled to final code using llc. This is useful in case additional passes or params are to be added to llvm via llc.

An example workflow as provided in do.sh (invoked as ./do.sh PATH/TO/GRC/FILE):

./gracec -i -o < $1 > a.imm
llc-12 -regalloc=pbqp a.imm -o a.asm
clang a.asm libgrc.a -no-pie -o a.out

Optimizations

The following optimizations are applied:

• Local optimizations
• Intermediate code optimizations with data and control flow analysis
• Register allocation and final code optimizations

Library functions

The library function file libgrc.a is generated using code from this repo