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refactor(mir): Separate KeepAlive/ReleaseStrong instructions (Phase 287)

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Phase 287: KeepAlive/ReleaseStrong 命令分離

## 変更内容（2つの側面）

### 1. 命令セマンティクスの分離
- KeepAlive { values, drop_after: bool } を2命令に分離
  - KeepAlive { values }: スコープ終了での生存維持（PURE）
  - ReleaseStrong { values }: 変数上書き時の強参照解放（WRITE）
- 効果分析の明確化: PURE vs WRITE の境界確定

### 2. VM実行サポート
- handlers/mod.rs: KeepAlive → 完全 no-op
- handlers/mod.rs: ReleaseStrong → release_strong_refs() 呼び出し
- handlers/lifecycle.rs: handle_keepalive() 削除

## 影響範囲
- 10 ファイル修正（31箇所の出現を全変換）
- instruction.rs, builder.rs, lexical_scope.rs, methods.rs,
  display.rs, printer_helpers.rs, query.rs, joinir_id_remapper.rs,
  handlers/mod.rs, handlers/lifecycle.rs

## 検証
- 154/154 quick smoke PASS
- weak テスト回帰なし（weak_upgrade_fail, weak_basic）
- rg -n drop_after src → 0 件（完全除去確認）
- MIRダンプで release_strong/keepalive 正常表示

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
This commit is contained in:
tomoaki
2025-12-26 14:12:58 +09:00
parent f74ff6116c
commit 3bb865c6b0
10 changed files with 60 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
src/mir/builder.rs
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@ -601,14 +601,13 @@ impl MirBuilder {
// causing stale references after LoopForm transformation renumbers blocks.
// Result: VM would try to read undefined ValueIds (e.g., ValueId(270) at bb303).
if !var_name.starts_with("__pin$") {
// Phase 285 P2.1: Emit KeepAlive for previous value BEFORE updating variable_map
// Phase 287: Release strong references for previous value BEFORE updating variable_map
// This ensures "alive until overwrite, then dropped" semantics
// ⚠️ Termination guard: don't emit after return/throw
if !self.is_current_block_terminated() {
if let Some(prev) = self.variable_ctx.variable_map.get(&var_name).copied() {
let _ = self.emit_instruction(MirInstruction::KeepAlive {
let _ = self.emit_instruction(MirInstruction::ReleaseStrong {
values: vec![prev],
drop_after: true, // Overwrite: drop old value after this
});
}
}

13
src/mir/builder/joinir_id_remapper.rs
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@ -146,8 +146,9 @@ impl JoinIrIdRemapper {
Print { value, .. } => vec![*value],
Debug { value, .. } => vec![*value],
DebugLog { values, .. } => values.clone(),
// Phase 285 P2.1: KeepAlive collects all values
KeepAlive { values, .. } => values.clone(),
// Phase 287: Lifecycle management collects all values
KeepAlive { values } => values.clone(),
ReleaseStrong { values } => values.clone(),
Throw { exception, .. } => vec![*exception],
Catch {
exception_value, ..
@ -319,10 +320,12 @@ impl JoinIrIdRemapper {
message: message.clone(),
values: values.iter().map(|&v| remap(v)).collect(),
},
// Phase 285 P2.1: KeepAlive remaps all values
KeepAlive { values, drop_after } => KeepAlive {
// Phase 287: Lifecycle management remaps all values
KeepAlive { values } => KeepAlive {
values: values.iter().map(|&v| remap(v)).collect(),
},
ReleaseStrong { values } => ReleaseStrong {
values: values.iter().map(|&v| remap(v)).collect(),
drop_after: *drop_after,
},
Throw { exception, effects } => Throw {
exception: remap(*exception),

5
src/mir/builder/vars/lexical_scope.rs
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@ -47,8 +47,8 @@ impl super::super::MirBuilder {
.pop_lexical_scope()
.expect("COMPILER BUG: pop_lexical_scope without push_lexical_scope");
// Phase 285 P2.1: Emit KeepAlive for all declared variables in this scope
// This keeps strong refs alive until scope end (language scope semantics)
// Phase 287: Emit KeepAlive for all declared variables in this scope
// This keeps values alive until scope end for PHI node inputs (liveness analysis)
// ⚠️ Termination guard: don't emit after return/throw
if !self.is_current_block_terminated() {
let keepalive_values: Vec<crate::mir::ValueId> = frame
@ -60,7 +60,6 @@ impl super::super::MirBuilder {
if !keepalive_values.is_empty() {
let _ = self.emit_instruction(crate::mir::MirInstruction::KeepAlive {
values: keepalive_values,
drop_after: false, // Scope-end: don't drop, values may be needed for PHI
});
}
}

17
src/mir/instruction.rs
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@ -220,15 +220,20 @@ pub enum MirInstruction {
values: Vec<ValueId>,
},
/// Phase 285 P2.1: Keep values alive until scope end
/// Phase 287: Keep values alive until scope end (for PHI, liveness analysis)
/// `keepalive %v1 %v2 ...`
/// Prevents DCE from removing values and maintains strong refs for language scope semantics.
/// - drop_after=true: Release values after this instruction (for variable overwrite)
/// - drop_after=false: Just keep alive (for scope end, values may be needed for PHI)
/// Effect: PURE (no side effects, only affects DCE/liveness)
/// Prevents DCE from removing values that may be needed for PHI nodes.
KeepAlive {
values: Vec<ValueId>,
/// If true, VM should drop the values after processing this instruction
drop_after: bool,
},
/// Phase 287: Release strong references (for variable overwrite, scope exit)
/// `release_strong %v1 %v2 ...`
/// Effect: WRITE (modifies reference count, may trigger deallocation)
/// Releases all strong references to the specified values, including SSA aliases.
ReleaseStrong {
values: Vec<ValueId>,
},
/// Print instruction for console output

12
src/mir/instruction/display.rs
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@ -138,12 +138,16 @@ impl fmt::Display for MirInstruction {
}
Ok(())
}
// Phase 285 P2.1: KeepAlive for language scope semantics
MirInstruction::KeepAlive { values, drop_after } => {
// Phase 287: Lifecycle management
MirInstruction::KeepAlive { values } => {
write!(f, "keepalive")?;
if *drop_after {
write!(f, "[drop]")?;
for v in values {
write!(f, " {}", v)?;
}
Ok(())
}
MirInstruction::ReleaseStrong { values } => {
write!(f, "release_strong")?;
for v in values {
write!(f, " {}", v)?;
}

9
src/mir/instruction/methods.rs
View File

@ -36,6 +36,9 @@ impl MirInstruction {
MirInstruction::Store { .. } | MirInstruction::ArraySet { .. } => EffectMask::WRITE,
MirInstruction::ArrayGet { .. } => EffectMask::READ,
// Phase 287: Reference lifecycle
MirInstruction::ReleaseStrong { .. } => EffectMask::WRITE,
// Function calls use provided effect mask
MirInstruction::Call { effects, .. }
| MirInstruction::BoxCall { effects, .. }
@ -133,6 +136,7 @@ impl MirInstruction {
| MirInstruction::Debug { .. }
| MirInstruction::DebugLog { .. }
| MirInstruction::KeepAlive { .. }
| MirInstruction::ReleaseStrong { .. }
| MirInstruction::Print { .. }
| MirInstruction::Throw { .. }
| MirInstruction::RefSet { .. }
@ -237,8 +241,9 @@ impl MirInstruction {
} => vec![*array, *index, *value],
MirInstruction::DebugLog { values, .. } => values.clone(),
// Phase 285 P2.1: KeepAlive uses all values (keeps them alive for liveness analysis)
MirInstruction::KeepAlive { values, .. } => values.clone(),
// Phase 287: Lifecycle management uses all values
MirInstruction::KeepAlive { values } => values.clone(),
MirInstruction::ReleaseStrong { values } => values.clone(),
// Phase 256 P1.5: Select instruction uses cond, then_val, else_val
MirInstruction::Select {

14
src/mir/printer_helpers.rs
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@ -295,12 +295,18 @@ pub fn format_instruction(
s
}
// Phase 285 P2.1: KeepAlive for language scope semantics
MirInstruction::KeepAlive { values, drop_after } => {
// Phase 287: Lifecycle management
MirInstruction::KeepAlive { values } => {
let mut s = "keepalive".to_string();
if *drop_after {
s.push_str("[drop]");
for v in values {
s.push(' ');
s.push_str(&format!("{}", v));
}
s
}
MirInstruction::ReleaseStrong { values } => {
let mut s = "release_strong".to_string();
for v in values {
s.push(' ');
s.push_str(&format!("{}", v));

5
src/mir/query.rs
View File

@ -85,8 +85,9 @@ impl<'m> MirQuery for MirQueryBox<'m> {
NewBox { args, .. } => args.clone(),
Debug { value, .. } | Print { value, .. } => vec![*value],
DebugLog { values, .. } => values.clone(),
// Phase 285 P2.1: KeepAlive reads all values
KeepAlive { values, .. } => values.clone(),
// Phase 287: Lifecycle management reads all values
KeepAlive { values } => values.clone(),
ReleaseStrong { values } => values.clone(),
Throw { exception, .. } => vec![*exception],
Catch { .. } => Vec::new(),
NewClosure { captures, me, .. } => {