feat(es/minifier): Implement more rules for hoist_props (#4262)

crates/swc/tests/tsc-references/arrowFunctionExpressions_es5.2.minified.js

@@ -11,6 +11,4 @@ var MyClass = function() {
     }
     return MyClass.prototype.fn = function() {}, MyClass;
 }();
-(function() {
+0..toExponential();
-    return 0;
-})().toExponential();

crates/swc/tests/tsc-references/bitwiseNotOperatorWithAnyOtherType_es5.2.minified.js

@@ -2,10 +2,7 @@ import * as swcHelpers from "@swc/helpers";
 var M, ANY2 = [
     "",
     ""
-], obj1 = {
+], A = function() {
-    x: "",
-    y: function() {}
-}, A = function() {
     "use strict";
     function A() {
         swcHelpers.classCallCheck(this, A);
@@ -17,4 +14,4 @@ var M, ANY2 = [
     M1.n = n;
 }(M || (M = {}));
 var objA = new A();
-ANY2[0], obj1.y, objA.a, M.n, A.foo(), ANY2[0], obj1.y, objA.a, M.n;
+ANY2[0], objA.a, M.n, A.foo(), ANY2[0], objA.a, M.n;

crates/swc/tests/tsc-references/callSignaturesWithOptionalParameters_es5.2.minified.js

@@ -10,9 +10,3 @@ var C = function() {
     return C.prototype.foo = function(x) {}, C;
 }();
 c.foo(), c.foo(1), i(), i(1), i.foo(1), i.foo(1, 2), a(), a(1), a.foo(), a.foo(1);
-var b = {
-    foo: function(x) {},
-    a: function(x, y) {},
-    b: function(x) {}
-};
-b.foo(), b.foo(1), b.a(1), b.a(1, 2), b.b(), b.b(1);

crates/swc/tests/tsc-references/plusOperatorWithAnyOtherType_es5.2.minified.js

@@ -2,10 +2,7 @@ import * as swcHelpers from "@swc/helpers";
 var M, ANY2 = [
     "",
     ""
-], obj1 = {
+], A = function() {
-    x: function(s) {},
-    y: function(s1) {}
-}, A = function() {
     "use strict";
     function A() {
         swcHelpers.classCallCheck(this, A);
@@ -17,4 +14,4 @@ var M, ANY2 = [
     M1.n = n;
 }(M || (M = {}));
 var objA = new A();
-ANY2[0], obj1.x, obj1.y, objA.a, M.n, A.foo(), ANY2[0], objA.a, M.n;
+ANY2[0], objA.a, M.n, A.foo(), ANY2[0], objA.a, M.n;

crates/swc/tests/tsc-references/unannotatedParametersAreOptional_es5.2.minified.js

@@ -7,8 +7,3 @@ var C = function() {
     return C.prototype.m = function(x) {}, C.m = function(x) {}, C;
 }();
 C.m(), new C().m(), new C().p();
-var obj = {
-    m: function(x) {},
-    p: function(x) {}
-};
-obj.m(), obj.p();

crates/swc_ecma_minifier/one.sh

@@ -8,4 +8,4 @@
 set -eux
 
 export RUST_LOG=swc_ecma_minifier=trace,swc_ecma_transforms_optimization=trace
-cargo test $@ --features debug --features swc_ecma_transforms_optimization/debug --test compress
+cargo test --features debug --features swc_ecma_transforms_optimization/debug --test compress $@ 

crates/swc_ecma_minifier/src/compress/optimize/hoist_props.rs

@@ -1,3 +1,4 @@
+use swc_common::DUMMY_SP;
 use swc_ecma_ast::*;
 use swc_ecma_utils::{contains_this_expr, ident::IdentLike};
 
@@ -98,6 +99,13 @@ where
                     if let Prop::KeyValue(p) = &**prop {
                         let value = match &*p.value {
                             Expr::Lit(..) => p.value.clone(),
+                            Expr::Fn(..) | Expr::Arrow(..) => {
+                                if self.options.hoist_props {
+                                    p.value.clone()
+                                } else {
+                                    continue;
+                                }
+                            }
                             _ => continue,
                         };
 
@@ -182,19 +190,27 @@ where
             _ => return,
         };
         if let Expr::Ident(obj) = &*member.obj {
+            if let MemberProp::Ident(prop) = &member.prop {
+                if let Some(mut value) = self
+                    .simple_props
+                    .get(&(obj.to_id(), prop.sym.clone()))
+                    .cloned()
+                {
+                    if let Expr::Fn(f) = &mut *value {
+                        f.function.span = DUMMY_SP;
+                    }
+
+                    tracing::debug!("hoist_props: Inlining `{}.{}`", obj.sym, prop.sym);
+                    self.changed = true;
+                    *e = *value;
+                    return;
+                }
+            }
+
             if let Some(value) = self.vars_for_prop_hoisting.remove(&obj.to_id()) {
                 member.obj = value;
                 self.changed = true;
                 tracing::debug!("hoist_props: Inlined a property");
-                return;
-            }
-
-            if let MemberProp::Ident(prop) = &member.prop {
-                if let Some(value) = self.simple_props.get(&(obj.to_id(), prop.sym.clone())) {
-                    tracing::debug!("hoist_props: Inlining `{}.{}`", obj.sym, prop.sym);
-                    self.changed = true;
-                    *e = *value.clone()
-                }
             }
         }
     }

crates/swc_ecma_minifier/src/compress/optimize/iife.rs

@@ -553,12 +553,45 @@ where
         self.lits.contains_key(id) || self.vars_for_inlining.contains_key(id)
     }
 
+    fn is_return_arg_simple_enough_for_iife_eval(&self, e: &Expr) -> bool {
+        match e {
+            Expr::Lit(..) | Expr::Ident(..) => true,
+
+            Expr::Bin(BinExpr {
+                op: op!("&&") | op!("||") | op!("??"),
+                ..
+            }) => false,
+
+            Expr::Bin(e) => {
+                self.is_return_arg_simple_enough_for_iife_eval(&e.left)
+                    && self.is_return_arg_simple_enough_for_iife_eval(&e.right)
+            }
+
+            _ => false,
+        }
+    }
+
     fn can_inline_fn_like(&self, param_ids: &[Ident], body: &BlockStmt) -> bool {
+        if contains_this_expr(body) || contains_arguments(body) {
+            return false;
+        }
+
+        if body.stmts.len() == 1 {
+            if let Stmt::Return(ReturnStmt { arg: Some(arg), .. }) = &body.stmts[0] {
+                if self.is_return_arg_simple_enough_for_iife_eval(arg) {
+                    return true;
+                }
+            }
+        }
+
         // Don't create top-level variables.
         if !param_ids.is_empty() && self.ctx.in_top_level() {
             for pid in param_ids {
                 if let Some(usage) = self.data.vars.get(&pid.to_id()) {
                     if usage.ref_count > 1 || usage.assign_count > 0 || usage.inline_prevented {
+                        if cfg!(feature = "debug") {
+                            tracing::trace!("iife: [x] Cannot inline because of usage of {}", pid);
+                        }
                         return false;
                     }
                 }
@@ -571,6 +604,12 @@ where
 
                 for param in param_ids {
                     if captured.contains(&param.to_id()) {
+                        if cfg!(feature = "debug") {
+                            tracing::trace!(
+                                "iife: [x] Cannot inline because of the capture of {}",
+                                param
+                            );
+                        }
                         return false;
                     }
                 }
@@ -639,10 +678,6 @@ where
             return false;
         }
 
-        if contains_this_expr(body) || contains_arguments(body) {
-            return false;
-        }
-
         true
     }
 
@@ -736,12 +771,13 @@ where
         }
 
         for (idx, param) in params.iter().enumerate() {
-            if let Some(arg) = args.get_mut(idx) {
+            let arg = args.get_mut(idx).map(|arg| arg.expr.take());
+            if let Some(arg) = arg {
                 exprs.push(Box::new(Expr::Assign(AssignExpr {
                     span: DUMMY_SP.apply_mark(self.marks.non_top_level),
                     op: op!("="),
                     left: PatOrExpr::Pat(Box::new(Pat::Ident(param.clone().into()))),
-                    right: arg.expr.take(),
+                    right: arg,
                 })));
             }
         }

crates/swc_ecma_minifier/tests/TODO.txt

@@ -122,6 +122,7 @@ dead_code/dead_code_constant_boolean_should_warn_more/input.js
 dead_code/dead_code_constant_boolean_should_warn_more_strict/input.js
 dead_code/global_fns/input.js
 dead_code/issue_2749/input.js
+dead_code/issue_2860_2/input.js
 dead_code/issue_718/input.js
 dead_code/return_assignment/input.js
 dead_code/unsafe_builtin/input.js
@@ -333,9 +334,6 @@ hoist_props/contains_this_2/input.js
 hoist_props/direct_access_1/input.js
 hoist_props/hoist_class/input.js
 hoist_props/hoist_class_with_new/input.js
-hoist_props/issue_2377_1/input.js
-hoist_props/issue_2377_2/input.js
-hoist_props/issue_2377_3/input.js
 hoist_props/issue_2473_3/input.js
 hoist_props/issue_2473_4/input.js
 hoist_props/issue_2508_1/input.js

crates/swc_ecma_minifier/tests/golden.txt

@@ -292,7 +292,6 @@ dead_code/issue_2666/input.js
 dead_code/issue_2692/input.js
 dead_code/issue_2701/input.js
 dead_code/issue_2860_1/input.js
-dead_code/issue_2860_2/input.js
 dead_code/issue_2929/input.js
 dead_code/throw_assignment/input.js
 dead_code/try_catch_finally/input.js
@@ -624,6 +623,9 @@ hoist_props/direct_access_2/input.js
 hoist_props/direct_access_3/input.js
 hoist_props/does_not_hoist_objects_with_computed_props/input.js
 hoist_props/hoist_function_with_call/input.js
+hoist_props/issue_2377_1/input.js
+hoist_props/issue_2377_2/input.js
+hoist_props/issue_2377_3/input.js
 hoist_props/issue_2462/input.js
 hoist_props/issue_2473_1/input.js
 hoist_props/issue_2473_2/input.js

crates/swc_ecma_minifier/tests/terser/compress/dead-code/issue_2860_2/config.json

@@ -2,6 +2,6 @@
     "dead_code": true,
     "evaluate": true,
     "inline": true,
-    "passes": 3,
+    "passes": 4,
     "reduce_vars": true
 }

crates/swc_ecma_minifier/tests/terser/compress/hoist_props/issue_2377_1/output.js

@@ -1,5 +1 @@
-var obj_foo = 1,
+console.log(1, 27);
-    obj_cube = function (x) {
-        return x * x * x;
-    };
-console.log(obj_foo, obj_cube(3));

crates/swc_ecma_minifier/tests/terser/compress/hoist_props/issue_2377_2/output.js

@@ -1,2 +1,2 @@
-console.log(1, ((x = 3), x * x * x));
 var x;
+console.log(1, 27);