Not to be confused with Yet Another Compiler Compiler (which I learned about only after naming this project...)
Version française : README-fr.md
Yet Another C Compiler is a simple compiler for a subset of the C programming language, written in Python, in the context of a compilation course in engineering school. It translates C code into assembly code for a minimal stack machine (MSM).
- Python 3.10 or higher
- GCC (for compiling the MSM simulator)
-
Clone the repository:
git clone https://github.com/AlexZeGamer/yacc.git cd yacc -
(optional) Install the project as a package:
pip install . -
Compile the MSM simulator:
cd msm gcc -o msm msm.c # or 'make msm' if make is installed
-
(optional) Add the MSM simulator to your PATH for easy access:
# Linux / WSL export PATH="$PATH:$(pwd)/msm" # Add this line to ~/.bashrc
# Windows PowerShell $env:PATH += ";$PWD/msm" # Add this line to your PowerShell profile
python yacc.py <parameters>or
yacc <parameters> # if installed as a packageInput :
input.cor--i <input.c>or--input <input.c>: Source file to compile--str="<source_code>": Instead of reading from a file, compile the provided C source code string--stdin: Read the C source code from standard input (e.g. via a pipe)
Output :
output.asmor--o <output.asm>or--output <output.asm>: Output assembly file--stdout: Print the generated assembly code to standard output instead of writing to a file (you can pipe it to the MSM simulator to run it directly, e.g.yacc input.c --stdout | ./msm/msm)
Other options :
-vor--verboseor--debug: Enable verbose mode for detailed output of every compilation step-hor--help: Show help message
To use the MSM simulator, you can pipe the output of the YACC compiler directly into the simulator. For example:
yacc input.c --stdout | ./msm/msmor
yacc input.c --stdout | msm # if msm is in your PATHCompile a C source file to an assembly file:
yacc input.c -o output.asmCompile a C source file and run it directly with the MSM simulator:
yacc input.c --stdout | msmCompile a C source code string and run it directly with the MSM simulator:
yacc --str="int main() { return 42; }" --stdout | msmCompile a C source file read from standard input and run it directly with the MSM simulator:
cat input.c | yacc --stdin --stdout | msmCompile a C source file with verbose output for debugging:
yacc input.c -o output.asm --verboseInstall the test runner once (for example with python -m pip install pytest) and execute the suite from the repository root:
python -m pytestYou can also target a single pipeline step by pointing pytest at the matching file, e.g. python -m pytest tests/test_parser.py to limit the run to parser tests.
The compilation process consists of the following steps (and implemented in the following files):
-
Lexical analysis (tokenisation):
lexer.py
Converts the input C source code into a list of tokens representing the smallest units of meaning (keywords, identifiers, operators, etc.) -
Syntax analysis (parsing):
parser.py
Parses the sequence of tokens to build an Abstract Syntax Tree (AST) representing the program structure -
Semantic analysis:
sema.py
Analyzes the AST to check for semantic errors (e.g., variable declarations, type checking) and annotates the AST with additional information -
Optimization:
optimizer.py
Performs optimizations on the AST to improve performance (e.g., constant folding, dead code elimination) -
Code generation (Codegen):
codegen.py
Generates the target assembly code from the optimized AST -
Optimization:
optimizer.py
Performs optimizations on the generated assembly code to improve performance (e.g., removing instructions that cancel each other out, etc.) -
Binary: (This step is done by the MSM simulator)
The generated assembly code is interpreted line by line to run the program
Show diagram
graph TB
left_CS(["Code Source"]) --> left_AL
subgraph Frontend
left_AL("**Lexical analysis (tokenisation)**<br>lexer.py") --> left_ASy
left_ASy("**Syntax analysis (parsing)**<br>parser.py") --> left_ASe
end
left_ASe("**Semantic analysis**<br>sema.py") --> left_Opt
left_Opt("**Optimization**<br>optimizer.py") --> left_GC
subgraph Backend
left_GC("**Code generation (Codegen)**<br>codegen.py") --> left_Opt2
end
left_Opt2("**Optimization**<br>optimizer.py") -- msm --> left_Bin
left_Bin(["**Binary**"])
-
Source code:
... if (a == 3) { b = 5; } ...
-
Lexical analysis (tokenisation):
... TOK_IF "if" TOK_LPARENTHESIS "(" TOK_IDENT "a" TOK_EQ "==" TOK_CONST "3" TOK_RPARENTHESIS ")" TOK_LBRACE "{" TOK_IDENT "a" TOK_AFFECT "=" TOK_CONST "5" TOK_SEMICOLON ";" TOK_RBRACE "}" ... TOK_EOF -
Syntax analysis (AST generation):
NODE_BLOCK ... ├── NODE_COND │ ├── NODE_EQ │ │ ├── NODE_REF a │ │ └── NODE_CONST #3 │ └── NODE_BLOCK │ └── NODE_DROP │ └── NODE_AFFECT │ ├── NODE_REF b │ └── NODE_CONST #5 ... -
Semantic analysis (AST verification & annotation):
NODE_BLOCK ... ├── NODE_COND │ ├── NODE_EQ │ │ ├── NODE_REF a @0 │ │ └── NODE_CONST #3 │ └── NODE_BLOCK │ └── NODE_DROP │ └── NODE_AFFECT │ ├── NODE_REF b @1 │ └── NODE_CONST #5 ... -
Optimization:
TODO -
Code generation:
... get 0 push 3 cmpeq jumpf L0_else push 5 dup set 0 drop 1 .L0_else ... -
Optimization:
TODO -
Binary:
0101010101101000111010...
Show diagram
graph TB
right_CS("**Source code :**<code><p style='text-align:left; white-space:pre;'>...
if (a == 3) {
</tr>b=5;
}
...</p></code>") --> right_AL
right_AL("**Lexic analyzer<br>(Tokenization) :**<code><p style='text-align:left;white-space:pre;'>...
TOK_IF "if"
TOK_LPARENTHESIS "("
TOK_IDENT "a"
TOK_EQ "=="
TOK_CONST "3"
TOK_RPARENTHESIS ")"
TOK_LBRACE "{"
TOK_IDENT "a"
TOK_AFFECT "="
TOK_CONST "5"
TOK_SEMICOLON ";"
TOK_RBRACE "}"
...
TOK_EOF</p></code>") --> right_ASy
right_ASy("**Syntax analysis<br>(AST generation) :**<code><p style='text-align:left; white-space:pre;'>NODE_BLOCK
...
├── NODE_COND
│ ├── NODE_EQ
│ │ ├── NODE_REF a
│ │ └── NODE_CONST #3
│ └── NODE_BLOCK
│ └── NODE_DROP
│ └── NODE_AFFECT
│ ├── NODE_REF b
│ └── NODE_CONST #5
...</p></code>") --> right_ASe
right_ASe("**Semantic analysis<br>(AST verification & annotation) :**<code><p style='text-align:left;white-space:pre;'>NODE_BLOCK
...
├── NODE_COND
│ ├── NODE_EQ
│ │ ├── NODE_REF a @0
│ │ └── NODE_CONST #3
│ └── NODE_BLOCK
│ └── NODE_DROP
│ └── NODE_AFFECT
│ ├── NODE_REF b @1
│ └── NODE_CONST #5
...</p></code>") --> right_Opt
right_Opt("**Optimization :**<code><p style='text-align:left;white-space:pre;'>TODO</p></code>") --> right_GC
right_GC("**Code generation :**<code><p style='text-align:left;white-space:pre;'>...
get 0
push 3
cmpeq
jumpf L0_else
push 5
dup
set 0
drop 1
.L0_else
...</p></code>") --> right_Opt2
right_Opt2("**Optimization :**<code><p style='text-align:left;white-space:pre;'>TODO</p></code>") -- msm --> right_Bin
right_Bin(["**Binary :**<code><p style='text-align:left;'>0101010101101000111010...</p></code>"])
| Alexandre MALFREYT (Github | LinkedIn | Website) |