Add LLVM IR codegen for `StructDefStmt` (struct type definitions)

[omsherikar]

Description

Implement the translation of astx.StructDefStmt to LLVM IR identified struct types. This is the foundation for struct support in IRx.

Background

• astx already provides StructDefStmt for defining structs
• IRx needs to translate this to LLVM's IdentifiedStructType
• Inspired by LLVM's CodeGenTypes.cpp

Tasks

• Add struct_types: dict[str, ir.IdentifiedStructType] in LLVMLiteIRVisitor to track struct name → LLVM type mapping
• Add struct_defs: dict[str, astx.StructDefStmt] to store struct definitions for field lookup
• Implement visit(node: astx.StructDefStmt) visitor method:
  • Create LLVM IdentifiedStructType using module.context.get_identified_type(name)
  • Map each field's astx type to LLVM type using get_data_type()
  • Set struct body with struct_type.set_body(*field_types)

Example Input (Python)

struct_def = astx.StructDefStmt(
    name="Point",
    attributes=[
        astx.VariableDeclaration(name="x", type_=astx.Int32()),
        astx.VariableDeclaration(name="y", type_=astx.Int32()),
    ],
)

Expected LLVM IR Output

%"Point" = type {i32, i32}

Files to Modify

• src/irx/builders/llvmliteir.py

Acceptance Criteria

• StructDefStmt translates to LLVM IdentifiedStructType
• Struct types are registered and can be looked up by name
• Unit test test_struct_definition passes

[omsherikar]

@xmnlab I have created a issue regarding defining the struct , Can you please have a look into it