hakorune/docs/development/current/main/phases/phase-136/README.md

Phase 136: loop(true) break-once with return literal

Date: 2025-12-18 Status: DONE ✅ Scope: return literal (Integer) support in Normalized shadow (dev-only)

---

Goal

Extend Phase 131-135 loop(true){...; break} to support return integer literal:

• Enable return 7 after loop exit
• Keep PHI禁止: merge via env + continuations only
• Keep dev-only and 既定挙動不変: unmatched shapes fall back

Supported Forms

✅ Supported (Phase 136)

// Form 1: loop + return literal
local x
x = 0
loop(true) {
    x = 1
    break
}
return 7  // Expected: 7 (literal, not variable)

// Form 2: loop + post assigns + return literal
local x
x = 0
loop(true) {
    x = 1
    break
}
x = x + 2
return 7  // Expected: 7 (literal)

❌ Not Supported (Out of Scope)

// Return expression (Phase 137+)
return x + 2

// Return string literal
return "hello"

// Return float literal
return 3.14

Implementation

Core Changes

File: src/mir/control_tree/normalized_shadow/loop_true_break_once.rs

Method: lower_return_value_to_vid() (行 638-743, Integer literal at 行 661)

Added Pattern: Integer literal

ASTNode::Literal { value: LiteralValue::Integer(i), .. } => {
    let const_vid = ValueId(*next_value_id);
    *next_value_id += 1;

    body.push(JoinInst::Compute(MirLikeInst::Const {
        dst: const_vid,
        value: ConstValue::Integer(*i),
    }));

    Ok(Some(const_vid))
}

Fixtures

1. phase136_loop_true_break_once_return_literal_min.hako

   • Pattern: loop(true){ x=1; break }; return 7
   • Expected: exit code 7

2. phase136_loop_true_break_once_post_return_literal_min.hako

   • Pattern: loop(true){ x=1; break }; x=x+2; return 7
   • Expected: exit code 7

Smoke Tests

VM:

• tools/smokes/v2/profiles/integration/apps/phase136_loop_true_break_once_return_literal_vm.sh
• tools/smokes/v2/profiles/integration/apps/phase136_loop_true_break_once_post_return_literal_vm.sh

LLVM EXE:

• tools/smokes/v2/profiles/integration/apps/phase136_loop_true_break_once_return_literal_llvm_exe.sh
• tools/smokes/v2/profiles/integration/apps/phase136_loop_true_break_once_post_return_literal_llvm_exe.sh

Verification

# Build
cargo build --release -p nyash-rust --features llvm

# Phase 136 smokes (4 tests)
bash tools/smokes/v2/profiles/integration/apps/phase136_loop_true_break_once_return_literal_vm.sh
bash tools/smokes/v2/profiles/integration/apps/phase136_loop_true_break_once_post_return_literal_vm.sh
bash tools/smokes/v2/profiles/integration/apps/phase136_loop_true_break_once_return_literal_llvm_exe.sh
bash tools/smokes/v2/profiles/integration/apps/phase136_loop_true_break_once_post_return_literal_llvm_exe.sh

# Regressions
bash tools/smokes/v2/profiles/integration/apps/phase131_loop_true_break_once_vm.sh
bash tools/smokes/v2/profiles/integration/apps/phase135_loop_true_break_once_post_empty_return_vm.sh

Acceptance Criteria

• ✅ Phase 136 VM: 2/2 PASS
• ✅ Phase 136 LLVM EXE: 2/2 PASS
• ✅ Phase 131/135 regression: 2/2 PASS
• ✅ Dev toggle OFF → no impact (Ok(None) fallback)

Key Design Points

Ok(None) for Fallback

• Unsupported patterns (e.g., return "hello") return Ok(None)
• Fallback to existing JoinIR routing (Pattern2, etc.)
• No hard errors for out-of-scope patterns

Const Generation Pattern (Phase 123)

• Const{dst, Integer(i)} → Ret{Some(dst)}
• Reused existing pattern from Phase 123

post_k/k_exit Both Supported

• Same helper used in both locations
• Unified return value lowering

Current Status

Phase 136 - DONE ✅ (2025-12-18)

VM/LLVM EXE parity achieved (exit code 7).