fix: if 无 else 假支显式写 undefined 消除寄存器初始化巧合依赖

Cargo.lock

@@ -1095,7 +1095,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_builtins"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "chrono",
  "fast-float",
@@ -1120,7 +1120,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_bytecode"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "num-bigint",
  "oxide_log",
@@ -1128,7 +1128,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_cfg"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "oxide_bytecode",
  "oxide_emit",
@@ -1139,7 +1139,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_cli"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "ansi_term",
  "bumpalo",
@@ -1159,7 +1159,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_code_cache"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "lru",
  "oxide_bytecode",
@@ -1168,7 +1168,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_compiler"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1187,7 +1187,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_dce"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1201,7 +1201,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_emit"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "num-bigint",
  "oxc_allocator",
@@ -1216,7 +1216,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_ir"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "oxide_bytecode",
  "oxide_log",
@@ -1225,7 +1225,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_kernel"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "bumpalo",
  "dashmap",
@@ -1240,7 +1240,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_liveness"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1252,7 +1252,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_log"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "tracing",
  "tracing-appender",
@@ -1261,7 +1261,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_parser"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "oxc_allocator",
  "oxc_ast",
@@ -1276,7 +1276,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_regalloc"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1292,7 +1292,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_runtime_api"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "num-bigint",
  "num-traits",
@@ -1304,7 +1304,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_test262"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "oxide_bytecode",
  "oxide_compiler",
@@ -1321,7 +1321,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_types"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "bumpalo",
  "hashbrown 0.14.5",
@@ -1333,7 +1333,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_vm"
-version = "0.8.14"
+version = "0.8.15"
 dependencies = [
  "bumpalo",
  "chrono",

Cargo.toml

@@ -22,7 +22,7 @@ members = [
 ]
 
 [workspace.package]
-version = "0.8.14"
+version = "0.8.15"
 edition = "2021"
 license = "MIT"
 rust-version = "1.80"

crates/oxide_emit/src/stmt/control.rs

@@ -32,9 +32,8 @@ impl Emitter {
             ctx.inst(Inst::load_const(Operand::Reg(result_reg), undef_idx));
         }
 
-        if ifs.alternate.is_some() {
+        // 真支无条件跳末尾，无 else 时防穿落假支。
-            ctx.inst(Inst::jmp(end_label));
+        ctx.inst(Inst::jmp(end_label));
-        }
 
         ctx.labels.set_label_pos(else_label, ctx.insts.len());
         if let Some(alt) = &ifs.alternate {
@@ -47,6 +46,11 @@ impl Emitter {
                 let undef_idx = ctx.add_constant(Constant::Undefined);
                 ctx.inst(Inst::load_const(Operand::Reg(result_reg), undef_idx));
             }
+        } else {
+            // 无 else 的假支显式写 undefined：完成值在所有路径都有定义，
+            // 不依赖寄存器文件初始值，防物理槽别名泄漏前值。
+            let undef_idx = ctx.add_constant(Constant::Undefined);
+            ctx.inst(Inst::load_const(Operand::Reg(result_reg), undef_idx));
         }
 
         ctx.labels.set_label_pos(end_label, ctx.insts.len());

crates/oxide_vm/tests/control_flow_tests.rs

@@ -41,6 +41,14 @@ fn eval_if_without_else_false() {
     assert_eq!(eval("if (false) { 42 }"), "undefined");
 }
 
+#[test]
+fn eval_if_no_else_false_branch_undefined() {
+    // 顶层脚本完成值直读 if 的 result_reg：假支前有用后死的 vreg（x 持 1，
+    // 被 keep 调用读取后死亡），其物理槽可能与 result_reg 别名。假支必须显式
+    // 写 undefined，不得泄漏该槽前值。
+    assert_eq!(eval("let x = 1; function keep(v){ return v; } keep(x); if (false) { }"), "undefined");
+}
+
 #[test]
 fn eval_dangling_else() {
     assert_eq!(eval("if (true) { if (false) { 1 } else { 2 } }"), "2");