190 lines
7.1 KiB
Rust
190 lines
7.1 KiB
Rust
//! # If-Expression JoinIR Lowering Router
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//!
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//! **Phase 33-12 Modularization**: Extracted from `mod.rs` (lines 201-423)
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//!
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//! ## Responsibility
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//! Routes if-expressions to appropriate JoinIR lowering strategies.
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//! This is the **main entry point** for if-expression → JoinIR lowering.
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//!
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//! ## Design Pattern
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//! - **Input**: AST if-expression + MirBuilder
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//! - **Output**: JoinModule (or error)
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//! - **Side effects**: Modifies MirBuilder (adds blocks, values, instructions)
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//!
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//! ## Why Separate Router?
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//! If and loop lowering are orthogonal concerns:
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//! - If: Expression-level lowering (conditional value selection)
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//! - Loop: Statement-level lowering (control flow patterns)
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//! - Keeping separate: Easier to extend, test, and maintain
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//!
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//! ## Related Modules
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//! - See also: `loop_pattern_router.rs` (loop lowering)
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//! - Parent: `mod.rs` (central lowering dispatcher)
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//!
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//! # Routing Strategy
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//!
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//! This router tries multiple lowering strategies in order:
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//! 1. **IfMerge**: For multiple-variable patterns (Phase 33-7)
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//! 2. **IfSelect**: For single-variable patterns (Phase 33-2/33-3)
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//!
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//! # Control Flow
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//!
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//! - Checks toggle flags (`joinir_if_select_enabled()`)
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//! - Validates function whitelist (test/Stage-1/explicit approvals)
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//! - Excludes loop-lowered functions (Phase 33-9.1 separation)
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//! - Falls back to traditional if_phi on pattern mismatch
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//!
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//! # Phase 61-1: If-in-Loop Support
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//!
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//! Context parameter enables if-in-loop lowering:
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//! - `None`: Pure if-expression
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//! - `Some(context)`: If-in-loop with carrier variables
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use crate::mir::join_ir::JoinInst;
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use crate::mir::{BasicBlockId, MirFunction};
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/// Phase 33-7: Try to lower if/else to JoinIR Select/IfMerge instruction
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///
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/// Scope:
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/// - Only applies to whitelisted functions:
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/// - IfSelectTest.* (Phase 33-2/33-3)
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/// - IfMergeTest.* (Phase 33-7)
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/// - JsonShapeToMap._read_value_from_pair/1 (Phase 33-4 Stage-1)
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/// - Stage1JsonScannerBox.value_start_after_key_pos/2 (Phase 33-4 Stage-B)
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/// - Requires JoinIR If-select toggle (HAKO_JOINIR_IF_SELECT / joinir_if_select_enabled)
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/// - Falls back to traditional if_phi on pattern mismatch
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///
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/// Pattern selection:
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/// - 1 variable → Select
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/// - 2+ variables → IfMerge
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///
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/// Phase 61-1: If-in-loop support
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/// - `context` parameter: If-in-loop context (carrier_names for loop variables)
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/// - None = Pure If, Some(_) = If-in-loop
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///
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/// Returns Some(JoinInst::Select) or Some(JoinInst::IfMerge) if pattern matched, None otherwise.
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pub fn try_lower_if_to_joinir(
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func: &MirFunction,
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block_id: BasicBlockId,
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debug: bool,
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context: Option<&crate::mir::join_ir::lowering::if_phi_context::IfPhiContext>, // Phase 61-1: If-in-loop context
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) -> Option<JoinInst> {
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// 1. dev/Core トグルチェック
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//
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// - Core: joinir_if_select_enabled()（JoinIR は常時 ON）
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// - Dev: joinir_dev_enabled()（詳細ログ等）
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//
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// 実際の挙動切り替えは joinir_if_select_enabled() に集約
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if !crate::config::env::joinir_if_select_enabled() {
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return None;
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}
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// Phase 185: strict check moved to caller (if_form.rs)
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// let strict_on = crate::config::env::joinir_strict_enabled();
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// Phase 33-9.1: Loop専任関数の除外（Loop/If責務分離）
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// Loop lowering対象関数はIf loweringの対象外にすることで、
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// 1関数につき1 loweringの原則を保証します
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if super::is_loop_lowered_function(&func.signature.name) {
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return None;
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}
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// Phase 33-8: デバッグログレベル取得（0-3）
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let debug_level = crate::config::env::joinir_debug_level();
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let _debug = debug || debug_level >= 1;
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// 2. Phase 33-8: 関数名ガード拡張（テスト + Stage-1 rollout + 明示承認）
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let is_allowed =
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// Test functions (always enabled)
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func.signature.name.starts_with("IfSelectTest.") ||
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func.signature.name.starts_with("IfSelectLocalTest.") || // Phase 33-10 test
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func.signature.name.starts_with("IfMergeTest.") ||
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func.signature.name.starts_with("IfToplevelTest.") || // Phase 61-4: loop-outside if test
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func.signature.name.starts_with("Stage1JsonScannerTestBox.") || // Phase 33-5 test
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// Stage-1 rollout (env-controlled)
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(crate::config::env::joinir_stage1_enabled() &&
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func.signature.name.starts_with("Stage1")) ||
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// Explicit approvals (Phase 33-4で検証済み, always on)
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matches!(func.signature.name.as_str(),
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"JsonShapeToMap._read_value_from_pair/1" |
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"Stage1JsonScannerBox.value_start_after_key_pos/2"
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);
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if !is_allowed {
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if debug_level >= 2 {
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eprintln!(
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"[try_lower_if_to_joinir] skipping non-allowed function: {}",
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func.signature.name
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);
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}
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return None;
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}
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// Phase 185: strict_allowed removed (strict check moved to caller: if_form.rs)
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if debug_level >= 1 {
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eprintln!(
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"[try_lower_if_to_joinir] trying to lower {}",
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func.signature.name
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);
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}
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// 3. Phase 33-7: IfMerge を優先的に試行（複数変数パターン）
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// IfMerge が成功すればそれを返す、失敗したら Select を試行
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// Phase 61-1: context がある場合は with_context() を使用
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let if_merge_lowerer = if let Some(ctx) = context {
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crate::mir::join_ir::lowering::if_merge::IfMergeLowerer::with_context(
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debug_level,
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ctx.clone(),
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)
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} else {
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crate::mir::join_ir::lowering::if_merge::IfMergeLowerer::new(debug_level)
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};
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if if_merge_lowerer.can_lower_to_if_merge(func, block_id) {
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if let Some(result) = if_merge_lowerer.lower_if_to_if_merge(func, block_id) {
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if debug_level >= 1 {
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eprintln!(
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"[try_lower_if_to_joinir] ✅ IfMerge lowering used for {}",
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func.signature.name
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);
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}
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return Some(result);
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}
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}
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// 4. IfMerge が失敗したら Select を試行（単一変数パターン）
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// Phase 61-1: context がある場合は with_context() を使用
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let if_select_lowerer = if let Some(ctx) = context {
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crate::mir::join_ir::lowering::if_select::IfSelectLowerer::with_context(
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debug_level,
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ctx.clone(),
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)
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} else {
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crate::mir::join_ir::lowering::if_select::IfSelectLowerer::new(debug_level)
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};
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// Phase 185: Remove strict checks from lowerer (thin Result-returning box)
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// Strict mode panic should happen at caller level (if_form.rs), not here
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if !if_select_lowerer.can_lower_to_select(func, block_id) {
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if debug_level >= 1 {
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eprintln!(
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"[try_lower_if_to_joinir] pattern not matched for {}",
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func.signature.name
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);
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}
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return None;
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}
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let result = if_select_lowerer.lower_if_to_select(func, block_id);
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if result.is_some() && debug_level >= 1 {
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eprintln!(
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"[try_lower_if_to_joinir] ✅ Select lowering used for {}",
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func.signature.name
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);
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}
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result
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}
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