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Compiler for an imperative toy programming language

License: MIT License

C++ 68.98% Lex 6.11% Yacc 17.88% CMake 1.43% Shell 0.10% Python 5.51%

bison compiler flex imperative-language llvm cpp language

cplus's Introduction

Сplus

Compiler for C+ toy imperative language, based on LLVM.

For language syntax, semantics, and examples check documentation.md
For formal language grammar, check grammar.md

Getting started

Code sample.cp

routine main() is
    println "Hello C+";
    return;
end

Compile

$ ./cplus sample.cp

Compilation successful. Run ./a.out to execute

Run
```
$ ./a.out
Hello C+
```

Generated ir.ll

; ModuleID = 'ir.ll'
source_filename = "ir.ll"
target triple = "x86_64-pc-linux-gnu"

@fmt_s_ln = private unnamed_addr constant [4 x i8] c"%s\0A\00", align 1
@str = private unnamed_addr constant [9 x i8] c"Hello C+\00", align 1

define i64 @main() {
entry:
  %printfCall = call i64 (i8*, ...) @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @fmt_s_ln, i32 0, i32 0), i8* getelementptr inbounds ([9 x i8], [9 x i8]* @str, i32 0, i32 0))
  ret i64 0
}

declare i64 @printf(i8*, ...)

Debug output from cplus -d sample.cp

Compilation from source (Linux)

Install prerequisites: cmake flex bison clang llvm-10 using the package manager for your distro.
- Example (Ubuntu 20.04 LTS): sudo apt install cmake flex bison clang llvm

Clone repo

git clone https://github.com/Sh3B0/cplus/
cd cplus

Build cplus binary using CMake

mkdir build
cmake -S . -B build
cmake --build build

Compile a source file *.cp (check tests)
```
cd build
./cplus -d ../tests/1.cp
```

Help

$ ./cplus --help
usage: cplus [options] infile
	infile                 path to the source code file (*.cp) to compile.

options:
	-h, --help             show this help message and exit.
	-d, --debug            show debug messages.
	-o, --outfile outfile  specify executable file name.

Contribution

Feel free to report a bug or suggest a feature by creating an issue.

License

The source code is licensed under the MIT license, which you can find in the LICENSE file.

cplus's People

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cplus's Issues

Example code

routine main() is
	var x : array[5] integer;
	x[-1] := -1;
	x[0] := 0;
	x[6] := 6;
	println x[-1];
	println x[0];
	println x[6];
	return;
end

Expected behavor

Runtime errors as we access invalid indexes (btw, C+ arrays are 1-indexed)

Actual behavior

Prints -1, 0, 6
Although seems cool, it shouldn't be like this.

Return statements inside basic blocks

Code to reproduce

routine power(number : integer, to_power : integer) : integer is
	var tmp is 1;
	if to_power < 1 then
		return 1;
	end
	for i in 0 .. to_power - 1 loop
		tmp := tmp * number;
	end
	return tmp;
end

routine main(input : integer) is 
	println power(2, 3);
	return;
end

Expected behavior

Prints 8

Actual behavior

[LLVM]: [WARNINGS]:
Terminator found in the middle of a basic block!
label %then

ir.ll:38:3: error: instruction expected to be numbered '%1'
  %0 = load i64, i64* %tmp
  ^
1 error generated.
Error generating IR

Comments

Return statements inside basic basic blocks (if/else label, for loop) always produce that warning, sometimes the program still work, but it's better to invistigate that issue as it might be the root cause.
Related question

Enhancements checklist

Add support for multidimensioan arrays and arrays of records.
Add support for recursive routines.
Allow using arrays/records as global variables and routine arguments.
Generate fmt consts as needed and remove is_first_routine hack.
Visiting identifier should only assign to tmp_p, loading into tmp_v should be done in AssignmentStatement only (this will make the IR much shorter).
Add support for Windows.

Code to reproduce

routine main(x: integer) : integer is
	println x;
	return 0;
end

$ ./cplus -d source.cp
$ ./a.out 5

Expected output

Prints 5

Actual output

Prints other random value, although the generated ir.ll seems correct.

Initializing a variable with record/array element

Code to reproduce

routine main() is
	var x : array[5] integer;
	x[1] := 1;
	var y is x[1];
	println y;
	return;
end

Expected behavior

Prints 1

Actual behavior

Prints garbage from memory, most probably the error originates from the local variable intialization code in VariableDeclarartion::visit

Code to reproduce

routine main() is
	var x : integer is 1.1;
	println x;
	return;
end

Expected behavior

Prints 1 as x is casted from real to integer.

Actual behavior

Prints 1.1, x is declared with real dtype as the code deduces dtype from iv disregarding user explicit type specification.
Can be fixed by modifying the visit method for VariableDeclaration to use casting as it's already done in AssignmentStatement.

Notes

Separate declaration then assignment does behave correctly.
Same problem happens with global variables, can be fixed in the same manner.
With routine calls and routine return statements, casting should also be implemented.

Assigning new values to arguments

Code to reproduce

routine modify(x : integer) is
    x := 2;
    println x;
    return;
end

routine main() is
    modify(5);
    return;
end

Expected behavior

Prints 2

Actual behavior

[AST]:
<Program>
|   <RoutineDeclaration>
|   |   <Body>
|   |   |   <AssignmentStatement>
|   |   |   |   <Identifier>
|   |   |   |   </Identifier>
cplus: /usr/lib/llvm-10/include/llvm/IR/Type.h:382: llvm::Type* llvm::Type::getPointerElementType() const: Assertion `getTypeID() == PointerTyID' failed.
./run.sh: line 5: 73279 Aborted                 (core dumped) ./build/cplus -d examples/sample.cp

Notes

This happens because the assignment statement tries to access the location of x by visiting the identifier node, which assigns to tmp_v rather than tmp_p in cast of argument (from args_table)
One way to solve this would be to make args_table return pointers instead of values (like ptrs_table), but this would require modifications in RoutineDeclarations.
We may actually use only one table (ptrs_table) and remove (args_table)

sh3b0 / cplus Goto Github PK

cplus's Introduction

Сplus

Getting started

Compilation from source (Linux)

Contribution

License

cplus's People

Contributors

Stargazers

Watchers

Forkers

cplus's Issues

Example code

Expected behavor

Actual behavior

Code to reproduce

Expected behavior

Actual behavior

Comments

Code to reproduce

Expected output

Actual output

Code to reproduce

Expected behavior

Actual behavior

Code to reproduce

Expected behavior

Actual behavior

Notes

Code to reproduce

Expected behavior

Actual behavior

Notes

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