Add `StructExpr` for creating struct instances with field initializers

[omsherikar]

Description

Create a way to instantiate structs with initial field values using a new StructExpr expression class.

Tasks

• Create StructExpr class in src/irx/system.py:
  • Store struct_type: StructType reference
  • Store field_values: Dict[str, astx.Expr] for field initializers
  • Generate unique name for the instance
• Implement visit(node: StructExpr) in llvmliteir.py:
  • Allocate struct on stack
  • For each field in struct definition:
    • Get value from field_values or use default
    • Use GEP to get field pointer
    • Store value to field
  • Return pointer to struct

Example Usage

point_type = StructType(struct_name="Point")

point_expr = StructExpr(
    struct_type=point_type,
    field_values={
        "x": astx.LiteralInt32(10),
        "y": astx.LiteralInt32(20),
    }
)

# Use in variable declaration
point_var = astx.VariableDeclaration(
    name="p", 
    type_=point_type, 
    value=point_expr
)

Expected LLVM IR Output

%struct_inst_0 = alloca %"Point"
%struct_inst_0.x_ptr = getelementptr %"Point", %"Point"* %struct_inst_0, i32 0, i32 0
store i32 10, i32* %struct_inst_0.x_ptr
%struct_inst_0.y_ptr = getelementptr %"Point", %"Point"* %struct_inst_0, i32 0, i32 1
store i32 20, i32* %struct_inst_0.y_ptr

Files to Modify

• src/irx/system.py - Add StructExpr class
• src/irx/builders/llvmliteir.py - Add StructExpr visitor

Dependencies

• Requires (struct type definition) Add LLVM IR codegen for StructDefStmt (struct type definitions) #143
• Requires (struct type reference) Add StructType for referencing defined structs in variable declarations #152

Acceptance Criteria

• StructExpr can create struct instances with field values
• Default values from struct definition are used when not provided
• Generated LLVM IR correctly initializes all fields
• Unit test test_struct_instantiation passes

[m-akhil-reddy]

hi @omsherikar , i would like work on this issue

[Jadhav-Dhanashri]

Hello mentainers,
I'm Dhanashri Jadhav, a GSOC aspirant.
Eager to contribute to GSoC projects & actively participate in Open Science Labs.
Looking forward to collaborating & learing from all of you.
Thank you!