[Self-Hosting] Phase 6: Implement IR Builder in Gradient

[graydeon]

Summary

Implement the IR builder in Gradient. Convert typed AST to Intermediate Representation for code generation.

Background

File: compiler/ir_builder.gr (~489 lines currently, stubs). Expand to ~2,000 lines with actual IR generation.

Target State

Full IR generation with:

• Expression lowering
• Statement lowering
• Function lowering
• SSA form construction
• Type conversion

Implementation Requirements

Core Functions

1. build_module(typed: TypedModule) -> IrModule

   • Lower entire module to IR
   • Generate all functions

2. build_function(func: TypedFunction) -> IrFunction

   • Lower function to IR
   • Create entry block
   • Generate parameters

3. build_expr(builder: IrBuilder, expr: TypedExpr) -> (IrBuilder, IrValue)

   • Lower expression to IR instructions
   • Handle all expression kinds
   • Return generated value

4. build_stmt(builder: IrBuilder, stmt: TypedStmt) -> IrBuilder

   • Lower statement to IR
   • Update builder state

5. create_block(builder: IrBuilder, name: String) -> (IrBuilder, BlockId)

   • Create new basic block
   • For control flow

IR Instructions to Generate

• Literals: const_int, const_float, const_bool
• Arithmetic: add, sub, mul, div
• Memory: alloca, load, store
• Control: br, br_cond, ret
• Calls: call, call_indirect
• Conversions: trunc, zext, inttoptr

Acceptance Criteria

• Can lower complete Gradient programs to IR
• Correct SSA form
• All expression types lowered
• All statement types lowered
• Proper block/branch structure
• Type-checks successfully
• Tests for lowering all constructs

Part Of

• Epic: Full Self-Hosting with Rust Kernel
• Phase: 6 of 7
• Blocks: Phase 7 (Codegen)

Effort

~5 days, ~1,500 lines of Gradient

Dependencies

• Phase 5 complete (LSP)
• May need memory allocation primitives in Rust