fix(regalloc): nested 子模块引用父槽无预着色保护致读错物理槽（B014）

子模块 alloc 时引用父槽的 LOAD_VAR.a/STORE_VAR.rd 被当作自身 vreg 染色移走，父侧 collect_escaped 只保护父不移动槽，子侧无对称保护。以 param_layout.base （inherited_reg_start 分界）识别父槽引用并预着色恒等，spill 自由色排除。新增 nested_parent_slot_regress 回归测试（field/method + 高压力变量）， workspace 全绿 + clippy 干净。
2026-08-06 20:34:55 +08:00
parent e667d5a329
commit d8aa902ff0
3 changed files with 145 additions and 0 deletions
@@ -0,0 +1,89 @@
+//! B013 延伸回归：nested 子模块直接槽引用父槽，RegAlloc on/off 运行时等价。
+//!
+//! 父侧 collect_escaped 保证父不移动槽；但子模块自身 alloc 时引用父槽的
+//! LOAD_VAR.a / STORE_VAR.rd 曾被当作子模块自己的 vreg 染色移走（→ 读错物理槽，
+//! on={object} vs off=42）。修复：graph.rs/rewrite.rs 对称 collect_own_escaped。
+//! 槽号 ≥ inherited_reg_start（param_layout.base）时触发，故用高压力变量推高槽号。
+
+use oxide_vm::vm::Vm;
+
+fn run_source(src: &str, regalloc: bool) -> (bool, String) {
+    let allocator = oxide_parser::Allocator::default();
+    let program = match oxide_parser::parse(&allocator, src) {
+        Ok(p) => p,
+        Err(e) => return (false, format!("parse error: {}", e[0].message)),
+    };
+    let mut ir = match oxide_emit::Emitter::new().emit_program(&program) {
+        Ok(i) => i,
+        Err(e) => return (false, format!("emit error: {e}")),
+    };
+    oxide_dce::dce(&mut ir);
+    if regalloc {
+        let cfg = oxide_cfg::build_cfg(&ir);
+        let live = oxide_liveness::liveness(&ir, &cfg);
+        oxide_dce::dce_precise(&mut ir, &live);
+        let cfg2 = oxide_cfg::build_cfg(&ir);
+        let live2 = oxide_liveness::liveness(&ir, &cfg2);
+        if let Err(e) = oxide_regalloc::alloc(&mut ir, &live2) {
+            return (false, format!("alloc error: {e}"));
+        }
+    }
+    let module = match oxide_ir::lower::lower(&ir) {
+        Ok(m) => m,
+        Err(e) => return (false, format!("lower error: {e}")),
+    };
+    let mut vm = Vm::new();
+    match vm.run(&module) {
+        Ok(v) => (true, v.to_string()),
+        Err(e) => (false, e),
+    }
+}
+
+fn pressure(n: usize) -> String {
+    let mut src = String::new();
+    for i in 0..n {
+        src.push_str(&format!("var v{i} = {i}; "));
+    }
+    src
+}
+
+#[test]
+fn field_reads_outer_40_pressure() {
+    let src = format!("{}var a = 42; class C {{ p = a; }} new C().p;", pressure(40));
+    let off = run_source(&src, false);
+    let on = run_source(&src, true);
+    assert_eq!(on, off, "field 读外层 40 压力: off={off:?} on={on:?}");
+}
+
+#[test]
+fn method_reads_outer_40_pressure() {
+    let src = format!("{}var a = 42; class C {{ m() {{ return a; }} }} new C().m();", pressure(40));
+    let off = run_source(&src, false);
+    let on = run_source(&src, true);
+    assert_eq!(on, off, "method 读外层 40 压力: off={off:?} on={on:?}");
+}
+
+#[test]
+fn field_reads_outer_30_pressure() {
+    let src = format!("{}var a = 42; class C {{ p = a; }} new C().p;", pressure(30));
+    let off = run_source(&src, false);
+    let on = run_source(&src, true);
+    assert_eq!(on, off, "field 读外层 30 压力: off={off:?} on={on:?}");
+}
+
+#[test]
+fn field_reads_outer_25_pressure() {
+    let src = format!("{}var a = 42; class C {{ p = a; }} new C().p;", pressure(25));
+    let off = run_source(&src, false);
+    let on = run_source(&src, true);
+    assert_eq!(on, off, "field 读外层 25 压力: off={off:?} on={on:?}");
+}
+
+#[test]
+fn field_reads_outer_hi_last_40_pressure() {
+    let mut src = pressure(40);
+    src.push_str("var a_hi = 777; class C { p = a_hi; } new C().p;");
+    let off = run_source(&src, false);
+    let on = run_source(&src, true);
+    assert_eq!(on, off, "field 读外层末位 40 压力: off={off:?} on={on:?}");
+}