[Pkg-javascript-commits] [uglifyjs] 39/228: enable `collapse_vars` & `reduce_vars` by default - fix corner cases in `const` optimisation - deprecate `/*@const*/`
Jonas Smedegaard
dr at jones.dk
Sat Apr 15 14:25:14 UTC 2017
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js pushed a commit to branch master
in repository uglifyjs.
commit 4e49302916fe395f5c63992aa28c33392208fb27
Author: alexlamsl <alexlamsl at gmail.com>
Date: Fri Feb 24 01:46:57 2017 +0800
enable `collapse_vars` & `reduce_vars` by default
- fix corner cases in `const` optimisation
- deprecate `/*@const*/`
fixes #1497
closes #1498
---
README.md | 5 ++---
lib/compress.js | 12 +++++++-----
lib/scope.js | 12 +-----------
test/compress/const.js | 4 ++++
test/compress/dead-code.js | 10 ++++++----
test/compress/drop-unused.js | 31 +++++++++++++++++++++++++++++++
test/compress/evaluate.js | 1 +
test/compress/issue-1041.js | 6 ++++--
8 files changed, 56 insertions(+), 25 deletions(-)
diff --git a/README.md b/README.md
index 06ffa0e..1d0244e 100644
--- a/README.md
+++ b/README.md
@@ -469,8 +469,6 @@ separate file and include it into the build. For example you can have a
```javascript
const DEBUG = false;
const PRODUCTION = true;
-// Alternative for environments that don't support `const`
-/** @const */ var STAGING = false;
// etc.
```
@@ -481,7 +479,8 @@ and build your code like this:
UglifyJS will notice the constants and, since they cannot be altered, it
will evaluate references to them to the value itself and drop unreachable
code as usual. The build will contain the `const` declarations if you use
-them. If you are targeting < ES6 environments, use `/** @const */ var`.
+them. If you are targeting < ES6 environments which does not support `const`,
+using `var` with `reduce_vars` (enabled by default) should suffice.
<a name="codegen-options"></a>
diff --git a/lib/compress.js b/lib/compress.js
index 95e9c1b..2bc1c5a 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -69,8 +69,8 @@ function Compressor(options, false_by_default) {
hoist_vars : false,
if_return : !false_by_default,
join_vars : !false_by_default,
- collapse_vars : false,
- reduce_vars : false,
+ collapse_vars : !false_by_default,
+ reduce_vars : !false_by_default,
cascade : !false_by_default,
side_effects : !false_by_default,
pure_getters : false,
@@ -1252,7 +1252,7 @@ merge(Compressor.prototype, {
this._evaluating = true;
try {
var d = this.definition();
- if ((d.constant || compressor.option("reduce_vars") && !d.modified) && d.init) {
+ if (compressor.option("reduce_vars") && !d.modified && d.init) {
if (compressor.option("unsafe")) {
if (!HOP(d.init, '_evaluated')) {
d.init._evaluated = ev(d.init, compressor);
@@ -3025,9 +3025,11 @@ merge(Compressor.prototype, {
return make_node(AST_Infinity, self).transform(compressor);
}
}
- if (compressor.option("evaluate") && !isLHS(self, compressor.parent())) {
+ if (compressor.option("evaluate")
+ && compressor.option("reduce_vars")
+ && !isLHS(self, compressor.parent())) {
var d = self.definition();
- if (d && d.constant && d.init && d.init.is_constant(compressor)) {
+ if (d.constant && !d.modified && d.init && d.init.is_constant(compressor)) {
var original_as_string = self.print_to_string();
var const_node = make_node_from_constant(compressor, d.init.constant_value(compressor), self);
var const_node_as_string = const_node.print_to_string();
diff --git a/lib/scope.js b/lib/scope.js
index b0d92d7..29e4103 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -97,7 +97,6 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
var scope = self.parent_scope = null;
var labels = new Dictionary();
var defun = null;
- var last_var_had_const_pragma = false;
var tw = new TreeWalker(function(node, descend){
if (options.screw_ie8 && node instanceof AST_Catch) {
var save_scope = scope;
@@ -154,13 +153,10 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
// later.
(node.scope = defun.parent_scope).def_function(node);
}
- else if (node instanceof AST_Var) {
- last_var_had_const_pragma = node.has_const_pragma();
- }
else if (node instanceof AST_SymbolVar
|| node instanceof AST_SymbolConst) {
var def = defun.def_variable(node);
- def.constant = node instanceof AST_SymbolConst || last_var_had_const_pragma;
+ def.constant = node instanceof AST_SymbolConst;
def.init = tw.parent().value;
}
else if (node instanceof AST_SymbolCatch) {
@@ -369,12 +365,6 @@ AST_Symbol.DEFMETHOD("global", function(){
return this.definition().global;
});
-AST_Var.DEFMETHOD("has_const_pragma", function() {
- var comments_before = this.start && this.start.comments_before;
- var lastComment = comments_before && comments_before[comments_before.length - 1];
- return lastComment && /@const\b/.test(lastComment.value);
-});
-
AST_Toplevel.DEFMETHOD("_default_mangler_options", function(options){
return defaults(options, {
except : [],
diff --git a/test/compress/const.js b/test/compress/const.js
index dd175fc..f1f13f4 100644
--- a/test/compress/const.js
+++ b/test/compress/const.js
@@ -12,6 +12,7 @@ issue_1191: {
join_vars : true,
sequences : false,
collapse_vars : false,
+ reduce_vars : true,
}
input: {
function foo(rot) {
@@ -43,6 +44,7 @@ issue_1194: {
join_vars : true,
sequences : false,
collapse_vars : false,
+ reduce_vars : true,
}
input: {
function f1() {const a = "X"; return a + a;}
@@ -70,6 +72,7 @@ issue_1396: {
join_vars : true,
sequences : false,
collapse_vars : false,
+ reduce_vars : true,
}
input: {
function foo(a) {
@@ -140,6 +143,7 @@ regexp_literal_not_const: {
join_vars : true,
sequences : false,
collapse_vars : false,
+ reduce_vars : true,
}
input: {
(function(){
diff --git a/test/compress/dead-code.js b/test/compress/dead-code.js
index c83f204..2596e80 100644
--- a/test/compress/dead-code.js
+++ b/test/compress/dead-code.js
@@ -94,7 +94,8 @@ dead_code_const_declaration: {
loops : true,
booleans : true,
conditionals : true,
- evaluate : true
+ evaluate : true,
+ reduce_vars : true,
};
input: {
var unused;
@@ -119,7 +120,8 @@ dead_code_const_annotation: {
loops : true,
booleans : true,
conditionals : true,
- evaluate : true
+ evaluate : true,
+ reduce_vars : true,
};
input: {
var unused;
@@ -167,7 +169,8 @@ dead_code_const_annotation_complex_scope: {
loops : true,
booleans : true,
conditionals : true,
- evaluate : true
+ evaluate : true,
+ reduce_vars : true,
};
input: {
var unused_var;
@@ -201,6 +204,5 @@ dead_code_const_annotation_complex_scope: {
var beef = 'good';
var meat = 'beef';
var pork = 'bad';
- 'good' === pork && console.log('reached, not const');
}
}
diff --git a/test/compress/drop-unused.js b/test/compress/drop-unused.js
index f5a88f2..c1ca1b5 100644
--- a/test/compress/drop-unused.js
+++ b/test/compress/drop-unused.js
@@ -648,3 +648,34 @@ drop_value: {
foo(), bar();
}
}
+
+const_assign: {
+ options = {
+ evaluate: true,
+ reduce_vars: true,
+ unused: true,
+ }
+ input: {
+ function f() {
+ const b = 2;
+ return 1 + b;
+ }
+
+ function g() {
+ const b = 2;
+ b = 3;
+ return 1 + b;
+ }
+ }
+ expect: {
+ function f() {
+ return 3;
+ }
+
+ function g() {
+ const b = 2;
+ b = 3;
+ return 1 + b;
+ }
+ }
+}
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
index f88bc53..ae5e58d 100644
--- a/test/compress/evaluate.js
+++ b/test/compress/evaluate.js
@@ -602,6 +602,7 @@ unsafe_prototype_function: {
call_args: {
options = {
evaluate: true,
+ reduce_vars: true,
}
input: {
const a = 1;
diff --git a/test/compress/issue-1041.js b/test/compress/issue-1041.js
index 9dd176f..cdbc22c 100644
--- a/test/compress/issue-1041.js
+++ b/test/compress/issue-1041.js
@@ -13,7 +13,8 @@ const_declaration: {
const_pragma: {
options = {
- evaluate: true
+ evaluate: true,
+ reduce_vars: true,
};
input: {
@@ -27,7 +28,8 @@ const_pragma: {
// for completeness' sake
not_const: {
options = {
- evaluate: true
+ evaluate: true,
+ reduce_vars: true,
};
input: {
--
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