Optimize property access evaluation

lib/compress/evaluate.js

@@ -342,7 +342,7 @@ const regexp_flags = new Set([
 ]);
 
 def_eval(AST_PropAccess, function (compressor, depth) {
-    const obj = this.expression._eval(compressor, depth);
+    let obj = this.expression._eval(compressor, depth + 1);
     if (obj === nullish || (this.optional && obj == null)) return nullish;
     if (compressor.option("unsafe")) {
         var key = this.property;
@@ -352,7 +352,6 @@ def_eval(AST_PropAccess, function (compressor, depth) {
                 return this;
         }
         var exp = this.expression;
-        var val;
         if (is_undeclared_ref(exp)) {
 
             var aa;
@@ -369,29 +368,29 @@ def_eval(AST_PropAccess, function (compressor, depth) {
             }
             if (!is_pure_native_value(exp.name, key))
                 return this;
-            val = global_objs[exp.name];
+            obj = global_objs[exp.name];
         } else {
-            val = exp._eval(compressor, depth + 1);
-            if (val instanceof RegExp) {
+            if (obj instanceof RegExp) {
                 if (key == "source") {
-                    return regexp_source_fix(val.source);
+                    return regexp_source_fix(obj.source);
                 } else if (key == "flags" || regexp_flags.has(key)) {
-                    return val[key];
+                    return obj[key];
                 }
             }
-            if (!val || val === exp || !HOP(val, key))
+            if (!obj || obj === exp || !HOP(obj, key))
                 return this;
-            if (typeof val == "function")
+
+            if (typeof obj == "function")
                 switch (key) {
                     case "name":
-                        return val.node.name ? val.node.name.name : "";
+                        return obj.node.name ? obj.node.name.name : "";
                     case "length":
-                        return val.node.length_property();
+                        return obj.node.length_property();
                     default:
                         return this;
                 }
         }
-        return val[key];
+        return obj[key];
     }
     return this;
 });

lib/compress/index.js

@@ -3799,6 +3799,12 @@ def_optimize(AST_Dot, function(self, compressor) {
         const sub = self.flatten_object(self.property, compressor);
         if (sub) return sub.optimize(compressor);
     }
+
+    if (self.expression instanceof AST_PropAccess
+        && parent instanceof AST_PropAccess) {
+        return self;
+    }
+
     let ev = self.evaluate(compressor);
     if (ev !== self) {
         ev = make_node_from_constant(ev, self).optimize(compressor);

test/compress/evaluate.js

@@ -1851,3 +1851,17 @@ regexp_property_eval: {
         console.log(false);
     }
 }
+
+
+unsafe_deep_chain: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z;
+    }
+    expect: {
+        a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z;
+    }
+}