WIP: Implementing Symbolic ASR pass

[anutosh491]

The pass should be responsible for converting the ASR of Program 1 to Prorgam 2
Program 1

from lpython import S
from sympy import pi

def main0():
    x: S = pi
    print(x)

if __name__ == "__main__":
   main0()

Program 2

from lpython import ccall, CPtr, p_c_pointer, pointer, i64, empty_c_void_p
import os

@ccall(header="symengine/cwrapper.h", c_shared_lib="symengine", c_shared_lib_path=f"{os.environ['CONDA_PREFIX']}/lib")
def basic_new_stack(x: CPtr) -> None:
    pass

@ccall(header="symengine/cwrapper.h", c_shared_lib="symengine", c_shared_lib_path=f"{os.environ['CONDA_PREFIX']}/lib")
def basic_const_pi(x: CPtr) -> None:
    pass

@ccall(header="symengine/cwrapper.h", c_shared_lib="symengine", c_shared_lib_path=f"{os.environ['CONDA_PREFIX']}/lib")
def basic_str(x: CPtr) -> str:
    pass

def main0():
    y: i64 = i64(0)
    x: CPtr = empty_c_void_p()
    p_c_pointer(pointer(y, i64), x)
    basic_new_stack(x)
    basic_const_pi(x)
    print(basic_str(x))

if __name__ == "__main__":
   main0()

[certik]

Very good, great plan.

[Thirumalai-Shaktivel]

Let's do this operation in the visit_variable itself.
And remove both visit_Module and visit_Function.
I think PassVisitor handles everything, Even transform_stmts.

[Thirumalai-Shaktivel]

You can access the Function scope using current_scope and the Module scope using current_scope->parent.

[Thirumalai-Shaktivel]

Store all the statements in pass_result.

[anutosh491]

Ok so if we get rid of visit_Module and visit_Function ,
the scope for function is x.m_parent_symtab and that of module is x.m_parent_symtab->parent right ?

[Thirumalai-Shaktivel]

Yup, that would work, but let's use current_scope instead.
PassVisitor would have assigned current_scope with x.m_symtab in visit_Function (in asr.h: ASRPassBaseWalkVisitor).
So you can use current_scope to access the Function scope and current_scope-> parent to access the Module scope.

[Thirumalai-Shaktivel]

If this: #2200 (comment) doesn't work, pass m_global_scope as an argument to ReplaceSymbolicVisitor and pass that symtab to PassVisitor instead of nullptr.

[certik]

Thanks @Thirumalai-Shaktivel for the review!

[Thirumalai-Shaktivel]

That's it!
Everything looks good to me, Add a test and Fix the CI failure!

[Thirumalai-Shaktivel]

Remove this, as we already assign it in the Function visitor!

[Thirumalai-Shaktivel]

Great job, @anutosh491!
LGTM!