phase29aa(p5): multi-pred return join when states match

src/bin/rc_insertion_selfcheck.rs

@@ -280,6 +280,101 @@ fn main() {
         "jump_chain_single_pred",
     );
 
+    // Case 3.7: Multi-predecessor Return with MATCHING states
+    // P5: すべての incoming end_state が完全一致する場合のみ ReturnCleanup を成立させる
+    let ptr = ValueId::new(370);
+    let v_shared = ValueId::new(23); // 同じValueIdを両predecessorで使用
+
+    let mut block_a = BasicBlock::new(BasicBlockId::new(0));
+    block_a.instructions = vec![MirInstruction::Store { value: v_shared, ptr }];
+    block_a.instruction_spans = vec![Span::unknown()];
+    block_a.terminator = Some(MirInstruction::Jump {
+        target: BasicBlockId::new(2),
+        edge_args: None,
+    });
+    block_a.terminator_span = Some(Span::unknown());
+
+    let mut block_b = BasicBlock::new(BasicBlockId::new(1));
+    block_b.instructions = vec![MirInstruction::Store { value: v_shared, ptr }];
+    block_b.instruction_spans = vec![Span::unknown()];
+    block_b.terminator = Some(MirInstruction::Jump {
+        target: BasicBlockId::new(2),
+        edge_args: None,
+    });
+    block_b.terminator_span = Some(Span::unknown());
+
+    let mut block_ret = BasicBlock::new(BasicBlockId::new(2));
+    block_ret.instructions = vec![];
+    block_ret.instruction_spans = vec![];
+    block_ret.terminator = Some(MirInstruction::Return { value: None });
+    block_ret.terminator_span = Some(Span::unknown());
+
+    let module = build_module_with_blocks(
+        vec![block_a, block_b, block_ret],
+        BasicBlockId::new(0),
+        "selfcheck_multi_pred_return_match",
+        "selfcheck_mod3p7",
+    );
+    assert_release_counts_in_blocks(
+        module,
+        "selfcheck_multi_pred_return_match",
+        1, // 全体で1（Return blockのみ）
+        &[
+            (BasicBlockId::new(0), 0), // Jump block: cleanup禁止
+            (BasicBlockId::new(1), 0), // Jump block: cleanup禁止
+            (BasicBlockId::new(2), 1), // Return block: multi-pred join成功
+        ],
+        "multi_pred_return_match",
+    );
+
+    // Case 3.8: Multi-predecessor Return with MISMATCHING states (negative test)
+    // P5: state不一致 → join state を作らない → ReturnCleanup なし
+    let ptr = ValueId::new(380);
+    let v1 = ValueId::new(24);
+    let v2 = ValueId::new(25); // 異なるValueId → state不一致
+
+    let mut block_a = BasicBlock::new(BasicBlockId::new(0));
+    block_a.instructions = vec![MirInstruction::Store { value: v1, ptr }];
+    block_a.instruction_spans = vec![Span::unknown()];
+    block_a.terminator = Some(MirInstruction::Jump {
+        target: BasicBlockId::new(2),
+        edge_args: None,
+    });
+    block_a.terminator_span = Some(Span::unknown());
+
+    let mut block_b = BasicBlock::new(BasicBlockId::new(1));
+    block_b.instructions = vec![MirInstruction::Store { value: v2, ptr }]; // v2 != v1 → 不一致
+    block_b.instruction_spans = vec![Span::unknown()];
+    block_b.terminator = Some(MirInstruction::Jump {
+        target: BasicBlockId::new(2),
+        edge_args: None,
+    });
+    block_b.terminator_span = Some(Span::unknown());
+
+    let mut block_ret = BasicBlock::new(BasicBlockId::new(2));
+    block_ret.instructions = vec![];
+    block_ret.instruction_spans = vec![];
+    block_ret.terminator = Some(MirInstruction::Return { value: None });
+    block_ret.terminator_span = Some(Span::unknown());
+
+    let module = build_module_with_blocks(
+        vec![block_a, block_b, block_ret],
+        BasicBlockId::new(0),
+        "selfcheck_multi_pred_return_mismatch",
+        "selfcheck_mod3p8",
+    );
+    assert_release_counts_in_blocks(
+        module,
+        "selfcheck_multi_pred_return_mismatch",
+        0, // 全体で0（join stateを作らないのでcleanupなし）
+        &[
+            (BasicBlockId::new(0), 0), // Jump block: cleanup禁止
+            (BasicBlockId::new(1), 0), // Jump block: cleanup禁止
+            (BasicBlockId::new(2), 0), // Return block: state不一致 → join失敗
+        ],
+        "multi_pred_return_mismatch",
+    );
+
     // Case 4: Jump terminator should NOT inject block-end cleanup (unsafe cross-block)
     let ptr = ValueId::new(400);
     let v1 = ValueId::new(30);