Pattern8 (Boolean Predicate Scan) implementation for is_integer/1:
- New pattern detection for `loop + if not predicate() { return false }`
- JoinIR lowerer with main/loop_step/k_exit structure
- Me receiver passed as param (by-name 禁止)
Key fixes:
1. expr_result = Some(join_exit_value) (Pattern7 style)
2. Tail-call: dst: None (no extra Ret instruction)
3. instruction_rewriter: Add `&& is_loop_header_with_phi` check
- Pattern8 has no carriers → no PHIs → MUST generate Copy bindings
- Without this, ValueId(103/104/105) were undefined
Status: Copy instructions now generated correctly, but exit block
creation issue remains (next step: Step A-C in指示書).
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
