579 lines
22 KiB
Rust
579 lines
22 KiB
Rust
/*!
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* MIR Loop Builder - SSA形式でのループ構築専用モジュール
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*
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* Sealed/Unsealed blockとPhi nodeを使った正しいループ実装
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* Based on Gemini's recommendation for proper SSA loop handling
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*/
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use super::{BasicBlockId, ConstValue, MirInstruction, ValueId};
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use crate::ast::ASTNode;
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use std::collections::{HashMap, HashSet};
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/// 不完全なPhi nodeの情報
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#[derive(Debug, Clone)]
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struct IncompletePhi {
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/// Phi nodeの結果ValueId
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phi_id: ValueId,
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/// 変数名
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var_name: String,
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/// 既知の入力値 (predecessor block id, value)
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known_inputs: Vec<(BasicBlockId, ValueId)>,
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}
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/// ループビルダー - SSA形式でのループ構築を管理
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pub struct LoopBuilder<'a> {
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/// 親のMIRビルダーへの参照
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parent_builder: &'a mut super::builder::MirBuilder,
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/// ループ内で追跡する変数の不完全Phi node
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incomplete_phis: HashMap<BasicBlockId, Vec<IncompletePhi>>,
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/// ブロックごとの変数マップ（スコープ管理）
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#[allow(dead_code)]
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block_var_maps: HashMap<BasicBlockId, HashMap<String, ValueId>>,
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/// ループヘッダーID（continueで使用）
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loop_header: Option<BasicBlockId>,
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/// continue文からの変数スナップショット
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continue_snapshots: Vec<(BasicBlockId, HashMap<String, ValueId>)>,
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/// PHI を生成しないモードかどうか
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no_phi_mode: bool,
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}
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// Local copy: detect a variable name assigned within an AST fragment
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fn extract_assigned_var_local(ast: &ASTNode) -> Option<String> {
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match ast {
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ASTNode::Assignment { target, .. } => {
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if let ASTNode::Variable { name, .. } = target.as_ref() {
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Some(name.clone())
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} else {
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None
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}
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}
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ASTNode::Program { statements, .. } => statements
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.last()
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.and_then(|st| extract_assigned_var_local(st)),
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ASTNode::If {
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then_body,
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else_body,
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..
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} => {
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let then_prog = ASTNode::Program {
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statements: then_body.clone(),
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span: crate::ast::Span::unknown(),
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};
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let tvar = extract_assigned_var_local(&then_prog);
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let evar = else_body.as_ref().and_then(|eb| {
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let ep = ASTNode::Program {
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statements: eb.clone(),
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span: crate::ast::Span::unknown(),
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};
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extract_assigned_var_local(&ep)
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});
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match (tvar, evar) {
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(Some(tv), Some(ev)) if tv == ev => Some(tv),
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_ => None,
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}
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}
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_ => None,
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}
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}
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impl<'a> LoopBuilder<'a> {
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// --- Small helpers for continue/break commonization ---
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/// Emit a jump to `target` from the current block and record predecessor metadata.
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fn jump_with_pred(&mut self, target: BasicBlockId) -> Result<(), String> {
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let cur_block = self.current_block()?;
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self.emit_jump(target)?;
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let _ = crate::mir::builder::loops::add_predecessor(self.parent_builder, target, cur_block);
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Ok(())
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}
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/// Switch insertion to a fresh (unreachable) block and place a Void const to keep callers satisfied.
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fn switch_to_unreachable_block_with_void(&mut self) -> Result<ValueId, String> {
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let next_block = self.new_block();
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self.set_current_block(next_block)?;
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let void_id = self.new_value();
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self.emit_const(void_id, ConstValue::Void)?;
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Ok(void_id)
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}
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/// Handle a `break` statement: jump to loop exit and continue in a fresh unreachable block.
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fn do_break(&mut self) -> Result<ValueId, String> {
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if let Some(exit_bb) = crate::mir::builder::loops::current_exit(self.parent_builder) {
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self.jump_with_pred(exit_bb)?;
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}
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self.switch_to_unreachable_block_with_void()
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}
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/// Handle a `continue` statement: snapshot vars, jump to loop header, then continue in a fresh unreachable block.
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fn do_continue(&mut self) -> Result<ValueId, String> {
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// Snapshot variables at current block to be considered as a predecessor input
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let snapshot = self.get_current_variable_map();
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let cur_block = self.current_block()?;
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self.block_var_maps.insert(cur_block, snapshot.clone());
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self.continue_snapshots.push((cur_block, snapshot));
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if let Some(header) = self.loop_header {
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self.jump_with_pred(header)?;
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}
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self.switch_to_unreachable_block_with_void()
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}
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/// 新しいループビルダーを作成
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pub fn new(parent: &'a mut super::builder::MirBuilder) -> Self {
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let no_phi_mode = parent.is_no_phi_mode();
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Self {
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parent_builder: parent,
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incomplete_phis: HashMap::new(),
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block_var_maps: HashMap::new(),
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loop_header: None,
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continue_snapshots: Vec::new(),
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no_phi_mode,
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}
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}
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/// SSA形式でループを構築
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pub fn build_loop(
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&mut self,
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condition: ASTNode,
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body: Vec<ASTNode>,
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) -> Result<ValueId, String> {
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// 1. ブロックの準備
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let preheader_id = self.current_block()?;
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let (header_id, body_id, after_loop_id) =
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crate::mir::builder::loops::create_loop_blocks(self.parent_builder);
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self.loop_header = Some(header_id);
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self.continue_snapshots.clear();
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// 2. Preheader -> Header へのジャンプ
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self.emit_jump(header_id)?;
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let _ = crate::mir::builder::loops::add_predecessor(self.parent_builder, header_id, preheader_id);
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// 3. Headerブロックの準備（unsealed状態）
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self.set_current_block(header_id)?;
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let _ = self.mark_block_unsealed(header_id);
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// 4. ループ変数のPhi nodeを準備
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// ここでは、ループ内で変更される可能性のある変数を事前に検出するか、
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// または変数アクセス時に遅延生成する
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self.prepare_loop_variables(header_id, preheader_id)?;
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// 5. 条件評価（Phi nodeの結果を使用）
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let condition_value = self.build_expression_with_phis(condition)?;
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// 6. 条件分岐
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self.emit_branch(condition_value, body_id, after_loop_id)?;
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let _ = crate::mir::builder::loops::add_predecessor(self.parent_builder, body_id, header_id);
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let _ = crate::mir::builder::loops::add_predecessor(self.parent_builder, after_loop_id, header_id);
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// 7. ループボディの構築
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self.set_current_block(body_id)?;
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// Optional safepoint per loop-iteration
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if std::env::var("NYASH_BUILDER_SAFEPOINT_LOOP")
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.ok()
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.as_deref()
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== Some("1")
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{
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self.emit_safepoint()?;
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}
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// ボディをビルド
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for stmt in body {
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self.build_statement(stmt)?;
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}
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// 8. Latchブロック（ボディの最後）からHeaderへ戻る
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// 現在の挿入先が latch（最後のブロック）なので、そのブロックIDでスナップショットを保存する
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let latch_id = self.current_block()?;
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let latch_snapshot = self.get_current_variable_map();
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// 以前は body_id に保存していたが、複数ブロックのボディや continue 混在時に不正確になるため
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// 実際の latch_id に対してスナップショットを紐づける
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self.block_var_maps.insert(latch_id, latch_snapshot);
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self.emit_jump(header_id)?;
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let _ = crate::mir::builder::loops::add_predecessor(self.parent_builder, header_id, latch_id);
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// 9. Headerブロックをシール（全predecessors確定）
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self.seal_block(header_id, latch_id)?;
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// 10. ループ後の処理
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self.set_current_block(after_loop_id)?;
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// Pop loop context
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crate::mir::builder::loops::pop_loop_context(self.parent_builder);
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// void値を返す
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let void_dst = self.new_value();
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self.emit_const(void_dst, ConstValue::Void)?;
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Ok(void_dst)
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}
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/// ループ変数の準備（事前検出または遅延生成）
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fn prepare_loop_variables(
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&mut self,
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header_id: BasicBlockId,
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preheader_id: BasicBlockId,
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) -> Result<(), String> {
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// 現在の変数マップから、ループで使用される可能性のある変数を取得
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let current_vars = self.get_current_variable_map();
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// preheader時点のスナップショット（後でphi入力の解析に使う）
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self.block_var_maps
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.insert(preheader_id, current_vars.clone());
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// 各変数に対して不完全なPhi nodeを作成
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let mut incomplete_phis = Vec::new();
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for (var_name, &value_before) in ¤t_vars {
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let phi_id = self.new_value();
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// 不完全なPhi nodeを作成（preheaderからの値のみ設定）
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let incomplete_phi = IncompletePhi {
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phi_id,
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var_name: var_name.clone(),
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known_inputs: vec![(preheader_id, value_before)],
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};
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incomplete_phis.push(incomplete_phi);
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if self.no_phi_mode {
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self.parent_builder
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.insert_edge_copy(preheader_id, phi_id, value_before)?;
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}
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// 変数マップを更新（Phi nodeの結果を使用）
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self.update_variable(var_name.clone(), phi_id);
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}
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// 不完全なPhi nodeを記録
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self.incomplete_phis.insert(header_id, incomplete_phis);
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Ok(())
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}
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/// ブロックをシールし、不完全なPhi nodeを完成させる
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fn seal_block(&mut self, block_id: BasicBlockId, latch_id: BasicBlockId) -> Result<(), String> {
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// 不完全なPhi nodeを取得
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if let Some(incomplete_phis) = self.incomplete_phis.remove(&block_id) {
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for mut phi in incomplete_phis {
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for (cid, snapshot) in &self.continue_snapshots {
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if let Some(v) = snapshot.get(&phi.var_name) {
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phi.known_inputs.push((*cid, *v));
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}
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}
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let value_after = self
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.get_variable_at_block(&phi.var_name, latch_id)
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.ok_or_else(|| format!("Variable {} not found at latch block", phi.var_name))?;
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phi.known_inputs.push((latch_id, value_after));
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if self.no_phi_mode {
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let mut seen: HashSet<BasicBlockId> = HashSet::new();
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for &(pred, val) in &phi.known_inputs {
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if seen.insert(pred) {
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self.parent_builder
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.insert_edge_copy(pred, phi.phi_id, val)?;
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}
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}
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} else {
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self.emit_phi_at_block_start(block_id, phi.phi_id, phi.known_inputs)?;
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}
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self.update_variable(phi.var_name.clone(), phi.phi_id);
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}
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}
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// ブロックをシール済みとしてマーク
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self.mark_block_sealed(block_id)?;
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Ok(())
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}
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// --- ヘルパーメソッド（親ビルダーへの委譲） ---
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fn current_block(&self) -> Result<BasicBlockId, String> {
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self.parent_builder
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.current_block
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.ok_or_else(|| "No current block".to_string())
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}
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fn new_block(&mut self) -> BasicBlockId {
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self.parent_builder.block_gen.next()
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}
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fn new_value(&mut self) -> ValueId {
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self.parent_builder.value_gen.next()
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}
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fn set_current_block(&mut self, block_id: BasicBlockId) -> Result<(), String> {
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self.parent_builder.start_new_block(block_id)
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}
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fn emit_jump(&mut self, target: BasicBlockId) -> Result<(), String> {
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self.parent_builder
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.emit_instruction(MirInstruction::Jump { target })
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}
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fn emit_branch(
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&mut self,
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condition: ValueId,
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then_bb: BasicBlockId,
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else_bb: BasicBlockId,
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) -> Result<(), String> {
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self.parent_builder
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.emit_instruction(MirInstruction::Branch {
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condition,
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then_bb,
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else_bb,
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})
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}
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fn emit_safepoint(&mut self) -> Result<(), String> {
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self.parent_builder
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.emit_instruction(MirInstruction::Safepoint)
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}
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fn emit_const(&mut self, dst: ValueId, value: ConstValue) -> Result<(), String> {
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self.parent_builder
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.emit_instruction(MirInstruction::Const { dst, value })
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}
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fn emit_phi_at_block_start(
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&mut self,
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block_id: BasicBlockId,
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dst: ValueId,
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inputs: Vec<(BasicBlockId, ValueId)>,
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) -> Result<(), String> {
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// Phi nodeをブロックの先頭に挿入
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if let Some(ref mut function) = self.parent_builder.current_function {
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if let Some(block) = function.get_block_mut(block_id) {
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// Phi命令は必ずブロックの先頭に配置
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let phi_inst = MirInstruction::Phi { dst, inputs };
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block.instructions.insert(0, phi_inst);
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Ok(())
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} else {
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Err(format!("Block {} not found", block_id))
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}
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} else {
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Err("No current function".to_string())
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}
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}
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#[allow(dead_code)]
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fn add_predecessor(&mut self, block: BasicBlockId, pred: BasicBlockId) -> Result<(), String> {
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if let Some(ref mut function) = self.parent_builder.current_function {
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if let Some(block) = function.get_block_mut(block) {
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block.add_predecessor(pred);
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Ok(())
|
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} else {
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Err(format!("Block {} not found", block))
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}
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} else {
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Err("No current function".to_string())
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}
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}
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|
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fn mark_block_unsealed(&mut self, _block_id: BasicBlockId) -> Result<(), String> {
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// ブロックはデフォルトでunsealedなので、特に何もしない
|
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// （既にBasicBlock::newでsealed: falseに初期化されている）
|
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Ok(())
|
||
}
|
||
|
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fn mark_block_sealed(&mut self, block_id: BasicBlockId) -> Result<(), String> {
|
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if let Some(ref mut function) = self.parent_builder.current_function {
|
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if let Some(block) = function.get_block_mut(block_id) {
|
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block.seal();
|
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Ok(())
|
||
} else {
|
||
Err(format!("Block {} not found", block_id))
|
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}
|
||
} else {
|
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Err("No current function".to_string())
|
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}
|
||
}
|
||
|
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fn get_current_variable_map(&self) -> HashMap<String, ValueId> {
|
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self.parent_builder.variable_map.clone()
|
||
}
|
||
|
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fn update_variable(&mut self, name: String, value: ValueId) {
|
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self.parent_builder.variable_map.insert(name, value);
|
||
}
|
||
|
||
fn get_variable_at_block(&self, name: &str, block_id: BasicBlockId) -> Option<ValueId> {
|
||
// まずブロックごとのスナップショットを優先
|
||
if let Some(map) = self.block_var_maps.get(&block_id) {
|
||
if let Some(v) = map.get(name) {
|
||
return Some(*v);
|
||
}
|
||
}
|
||
// フォールバック：現在の変数マップ（単純ケース用）
|
||
self.parent_builder.variable_map.get(name).copied()
|
||
}
|
||
|
||
fn build_expression_with_phis(&mut self, expr: ASTNode) -> Result<ValueId, String> {
|
||
// Phi nodeの結果を考慮しながら式を構築
|
||
self.parent_builder.build_expression(expr)
|
||
}
|
||
|
||
fn build_statement(&mut self, stmt: ASTNode) -> Result<ValueId, String> {
|
||
match stmt {
|
||
ASTNode::If {
|
||
condition,
|
||
then_body,
|
||
else_body,
|
||
..
|
||
} => {
|
||
// Lower a simple if inside loop, ensuring continue/break inside branches are handled
|
||
let cond_val = self.parent_builder.build_expression(*condition.clone())?;
|
||
let then_bb = self.new_block();
|
||
let else_bb = self.new_block();
|
||
let merge_bb = self.new_block();
|
||
self.emit_branch(cond_val, then_bb, else_bb)?;
|
||
|
||
// Capture pre-if variable map (used for phi normalization)
|
||
let pre_if_var_map = self.get_current_variable_map();
|
||
let pre_then_var_value = pre_if_var_map.clone();
|
||
|
||
// then
|
||
self.set_current_block(then_bb)?;
|
||
for s in then_body.iter().cloned() {
|
||
let _ = self.build_statement(s)?;
|
||
// Stop if block terminated
|
||
let cur_id = self.current_block()?;
|
||
let terminated = {
|
||
if let Some(ref fun_ro) = self.parent_builder.current_function {
|
||
if let Some(bb) = fun_ro.get_block(cur_id) {
|
||
bb.is_terminated()
|
||
} else {
|
||
false
|
||
}
|
||
} else {
|
||
false
|
||
}
|
||
};
|
||
if terminated {
|
||
break;
|
||
}
|
||
}
|
||
let then_var_map_end = self.get_current_variable_map();
|
||
// Only jump to merge if not already terminated (e.g., continue/break)
|
||
{
|
||
let cur_id = self.current_block()?;
|
||
let need_jump = {
|
||
if let Some(ref fun_ro) = self.parent_builder.current_function {
|
||
if let Some(bb) = fun_ro.get_block(cur_id) {
|
||
!bb.is_terminated()
|
||
} else {
|
||
false
|
||
}
|
||
} else {
|
||
false
|
||
}
|
||
};
|
||
if need_jump {
|
||
self.emit_jump(merge_bb)?;
|
||
}
|
||
}
|
||
|
||
// else
|
||
self.set_current_block(else_bb)?;
|
||
let mut else_var_map_end_opt: Option<
|
||
std::collections::HashMap<String, super::ValueId>,
|
||
> = None;
|
||
if let Some(es) = else_body.clone() {
|
||
for s in es.into_iter() {
|
||
let _ = self.build_statement(s)?;
|
||
let cur_id = self.current_block()?;
|
||
let terminated = {
|
||
if let Some(ref fun_ro) = self.parent_builder.current_function {
|
||
if let Some(bb) = fun_ro.get_block(cur_id) {
|
||
bb.is_terminated()
|
||
} else {
|
||
false
|
||
}
|
||
} else {
|
||
false
|
||
}
|
||
};
|
||
if terminated {
|
||
break;
|
||
}
|
||
}
|
||
else_var_map_end_opt = Some(self.get_current_variable_map());
|
||
}
|
||
{
|
||
let cur_id = self.current_block()?;
|
||
let need_jump = {
|
||
if let Some(ref fun_ro) = self.parent_builder.current_function {
|
||
if let Some(bb) = fun_ro.get_block(cur_id) {
|
||
!bb.is_terminated()
|
||
} else {
|
||
false
|
||
}
|
||
} else {
|
||
false
|
||
}
|
||
};
|
||
if need_jump {
|
||
self.emit_jump(merge_bb)?;
|
||
}
|
||
}
|
||
|
||
// Continue at merge
|
||
self.set_current_block(merge_bb)?;
|
||
// If both branches assign the same variable, emit phi and bind it
|
||
let then_prog = ASTNode::Program {
|
||
statements: then_body.clone(),
|
||
span: crate::ast::Span::unknown(),
|
||
};
|
||
let assigned_then = extract_assigned_var_local(&then_prog);
|
||
let assigned_else = else_body.as_ref().and_then(|es| {
|
||
let ep = ASTNode::Program {
|
||
statements: es.clone(),
|
||
span: crate::ast::Span::unknown(),
|
||
};
|
||
extract_assigned_var_local(&ep)
|
||
});
|
||
if let Some(var_name) = assigned_then {
|
||
let else_assigns_same = assigned_else
|
||
.as_ref()
|
||
.map(|s| s == &var_name)
|
||
.unwrap_or(false);
|
||
let then_value_for_var = then_var_map_end.get(&var_name).copied();
|
||
let else_value_for_var = if else_assigns_same {
|
||
else_var_map_end_opt
|
||
.as_ref()
|
||
.and_then(|m| m.get(&var_name).copied())
|
||
} else {
|
||
pre_then_var_value.get(&var_name).copied()
|
||
};
|
||
if let (Some(tv), Some(ev)) = (then_value_for_var, else_value_for_var) {
|
||
let phi_id = self.new_value();
|
||
if self.no_phi_mode {
|
||
self.parent_builder.insert_edge_copy(then_bb, phi_id, tv)?;
|
||
self.parent_builder.insert_edge_copy(else_bb, phi_id, ev)?;
|
||
} else {
|
||
self.emit_phi_at_block_start(
|
||
merge_bb,
|
||
phi_id,
|
||
vec![(then_bb, tv), (else_bb, ev)],
|
||
)?;
|
||
}
|
||
// Reset to pre-if map and bind the phi result
|
||
self.parent_builder.variable_map = pre_if_var_map.clone();
|
||
self.parent_builder.variable_map.insert(var_name, phi_id);
|
||
}
|
||
}
|
||
let void_id = self.new_value();
|
||
self.emit_const(void_id, ConstValue::Void)?;
|
||
Ok(void_id)
|
||
}
|
||
ASTNode::Break { .. } => self.do_break(),
|
||
ASTNode::Continue { .. } => self.do_continue(),
|
||
other => self.parent_builder.build_expression(other),
|
||
}
|
||
}
|
||
}
|