How to Generate IR for My Compiler?

Define the IR goals: simplicity, analyzability, optimization friendliness, and target independence

Choose an IR form: AST-based, three-address code, SSA, bytecode, or graph-based IR

Specify the IR data model: instructions, operands, types, basic blocks, functions, and modules

Define a stable instruction set: arithmetic, control flow, memory, calls, casts, and comparisons

Represent control flow explicitly with basic blocks and branch instructions

Lower source constructs into simpler IR constructs

Build symbol tables and type information before IR generation

Generate IR from the parsed AST using a recursive visitor or pattern-matching approach

Emit temporaries for intermediate results

Convert expressions into explicit instruction sequences

Convert statements into control-flow blocks and jumps

Create unique labels for branches, loops, and join points

Insert phi nodes if using SSA form

Normalize complex expressions into simpler operations

Handle short-circuit boolean logic with conditional branches

Handle function calls with argument evaluation and return value capture

Handle variable declarations, assignments, and scope management

Map source types to IR types

Insert explicit casts and conversions where needed

Represent memory operations with load and store instructions

Represent arrays, structs, and pointers with address calculation instructions

Preserve source locations for debugging and diagnostics

Validate IR invariants after generation

Run a verifier to check control-flow and type correctness

Build IR in passes if needed: initial lowering, cleanup, SSA construction, optimization prep

Use a builder API to append instructions to the current block

Maintain current function, current block, and insertion point during generation

Split critical edges and normalize branches if required by later passes

Eliminate unreachable blocks after generation

Canonicalize commutative operations and constant expressions

Fold constants during or after IR generation

Choose whether IR is in-memory only or serialized to a file format

Define a clear interface between frontend parsing and IR generation

Test IR generation with small source programs and expected IR snapshots

Compare generated IR against known-good cases for each language feature

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