Function compile_frontend_from_rir_with_options 

pub fn compile_frontend_from_rir_with_options(
    rir: Rir,
    interner: ThreadedRodeo,
    preview_features: &PreviewFeatures,
) -> MultiErrorResult<CompileStateFromRir>

Compile from already-generated RIR through remaining frontend phases.

This runs: semantic analysis → CFG construction → optimization. This is the optimized path used by parallel multi-file compilation, where RIR has already been generated per-file in parallel and merged.

Arguments

• rir - The RIR (already merged if from multiple files)
• interner - The shared string interner
• opt_level - Optimization level
• preview_features - Enabled preview features

Returns

A CompileStateFromRir containing the compilation state.