JoBoEVD/UglifyJS
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

clean up collapse_vars (#1826)

Browse Source 
- remove overlap in functionality of singular, consecutive reference of constant value
- remove workarounds for previous bugs in `lib/scope.js`
- distribute recursive `collapse_single_use_vars()` calls to their respective `OPT(AST_Node)`
- enable collapsing of variables within a single `AST_Definitions`
This commit is contained in:
Alex Lam S.L
2017-04-18 21:45:34 +08:00
committed by GitHub
parent 5d9f1da3ab
commit 0f4f01b66c
2 changed files with 192 additions and 163 deletions
Download Patch File Download Diff File Expand all files Collapse all files

119
lib/compress.js
View File

@@ -642,79 +642,72 @@ merge(Compressor.prototype, {
// and if it has exactly one reference then attempt to replace its reference
// in the statement with the var value and then erase the var definition.
var self = compressor.self();
var var_defs_removed = false;
var scope = compressor.find_parent(AST_Scope);
var toplevel = compressor.option("toplevel");
for (var stat_index = statements.length; --stat_index >= 0;) {
var stat = statements[stat_index];
if (stat instanceof AST_Definitions) continue;
// Process child blocks of statement if present.
[stat, stat.body, stat.alternative, stat.bcatch, stat.bfinally].forEach(function(node) {
node && node.body && collapse_single_use_vars(node.body, compressor);
});
// The variable definition must precede a statement.
if (stat_index <= 0) break;
var prev_stat_index = stat_index - 1;
var prev_stat = statements[prev_stat_index];
if (!(prev_stat instanceof AST_Definitions)) continue;
var var_defs = prev_stat.definitions;
if (var_defs == null) continue;
var var_names_seen = {};
var var_names_seen = Object.create(null);
var side_effects_encountered = false;
var lvalues_encountered = false;
var lvalues = {};
var lvalues = Object.create(null);
var prev_stat_index, var_defs, var_defs_index;
// Scan variable definitions from right to left.
for (var var_defs_index = var_defs.length; --var_defs_index >= 0;) {
if (stat instanceof AST_Definitions) {
prev_stat_index = stat_index;
var_defs = stat.definitions;
for (var_defs_index = var_defs.length - 1; --var_defs_index >= 0;) {
if (collapse(var_defs[var_defs_index + 1])) break;
}
} else if (stat_index > 0) {
// The variable definition must precede a statement.
prev_stat_index = stat_index - 1;
var prev_stat = statements[prev_stat_index];
if (!(prev_stat instanceof AST_Definitions)) continue;
var_defs = prev_stat.definitions;
for (var_defs_index = var_defs.length; --var_defs_index >= 0;) {
if (collapse(stat)) break;
}
}
}
// Obtain var declaration and var name with basic sanity check.
return statements;
function collapse(stat) {
var var_decl = var_defs[var_defs_index];
if (var_decl.value == null) break;
// `drop_unused()` shuffles variables without values to the top,
// so we can terminate upon first sighting as an optimization.
if (var_decl.value == null) return true;
var var_name = var_decl.name.name;
if (!var_name || !var_name.length) break;
// Bail if we've seen a var definition of same name before.
if (var_name in var_names_seen) break;
if (var_name in var_names_seen) return true;
var_names_seen[var_name] = true;
// Only interested in non-constant values.
if (var_decl.value.is_constant()) return;
// Only interested in cases with just one reference to the variable.
var def = self.find_variable && self.find_variable(var_name);
if (!def || !def.references || def.references.length !== 1
var def = var_decl.name.definition();
if (def.references.length !== 1
|| var_name == "arguments" || (!toplevel && def.global)) {
side_effects_encountered = true;
continue;
return;
}
var ref = def.references[0];
// Don't replace ref if eval() or with statement in scope.
if (ref.scope.uses_eval || ref.scope.uses_with) break;
// Constant single use vars can be replaced in any scope.
if (var_decl.value.is_constant()) {
var ctt = new TreeTransformer(function(node) {
var parent = ctt.parent();
if (parent instanceof AST_IterationStatement
&& (parent.condition === node || parent.init === node)) {
return node;
}
if (node === ref)
return replace_var(node, parent, true);
});
stat.transform(ctt);
continue;
}
if (ref.scope.uses_eval || ref.scope.uses_with) return true;
// Restrict var replacement to constants if side effects encountered.
if (side_effects_encountered |= lvalues_encountered) continue;
if (side_effects_encountered |= lvalues_encountered) return;
var value_has_side_effects = var_decl.value.has_side_effects(compressor);
// Non-constant single use vars can only be replaced in same scope.
if (ref.scope !== self) {
if (ref.scope !== scope) {
side_effects_encountered |= value_has_side_effects;
continue;
return;
}
// Detect lvalues in var value.
@@ -729,10 +722,9 @@ merge(Compressor.prototype, {
var unwind = false;
var tt = new TreeTransformer(
function preorder(node) {
if (unwind) return node;
if (unwind || node instanceof AST_Scope && node !== scope) return node;
var parent = tt.parent();
if (node instanceof AST_Lambda
|| node instanceof AST_Try
if (node instanceof AST_Try
|| node instanceof AST_With
|| node instanceof AST_Case
|| node instanceof AST_IterationStatement
@@ -740,7 +732,7 @@ merge(Compressor.prototype, {
|| (parent instanceof AST_Conditional && node !== parent.condition)
|| (node instanceof AST_SymbolRef
&& value_has_side_effects
&& !are_references_in_scope(node.definition(), self))
&& !are_references_in_scope(node.definition(), scope))
|| (parent instanceof AST_Binary
&& (parent.operator == "&&" || parent.operator == "||")
&& node === parent.right)
@@ -761,7 +753,7 @@ merge(Compressor.prototype, {
function postorder(node) {
if (unwind) return node;
if (node === ref)
return unwind = true, replace_var(node, tt.parent(), false);
return unwind = true, replace_var(var_decl, node, tt.parent(), false);
if (side_effects_encountered |= node.has_side_effects(compressor))
return unwind = true, node;
if (lvalues_encountered && node instanceof AST_SymbolRef && node.name in lvalues) {
@@ -772,21 +764,12 @@ merge(Compressor.prototype, {
);
stat.transform(tt);
}
}
// Remove extraneous empty statments in block after removing var definitions.
// Leave at least one statement in `statements`.
if (var_defs_removed) for (var i = statements.length; --i >= 0;) {
if (statements.length > 1 && statements[i] instanceof AST_EmptyStatement)
statements.splice(i, 1);
}
return statements;
function is_lvalue(node, parent) {
return node instanceof AST_SymbolRef && is_lhs(node, parent);
}
function replace_var(node, parent, is_constant) {
function replace_var(var_decl, node, parent, is_constant) {
if (is_lvalue(node, parent)) return node;
// Remove var definition and return its value to the TreeTransformer to replace.
@@ -795,14 +778,19 @@ merge(Compressor.prototype, {
var_defs.splice(var_defs_index, 1);
if (var_defs.length === 0) {
statements[prev_stat_index] = make_node(AST_EmptyStatement, self);
var_defs_removed = true;
statements.splice(prev_stat_index, 1);
stat_index--;
}
// Further optimize statement after substitution.
stat.reset_opt_flags(compressor);
compressor.info("Collapsing " + (is_constant ? "constant" : "variable") +
" " + var_name + " [{file}:{line},{col}]", node.start);
compressor.info("Collapsing {type} {name} [{file}:{line},{col}]", {
type: is_constant ? "constant" : "variable",
name: var_decl.name.name,
file: node.start.file,
line: node.start.line,
col: node.start.col
});
CHANGED = true;
return value;
}
@@ -1746,6 +1734,7 @@ merge(Compressor.prototype, {
def(AST_SymbolRef, function(compressor){
return this.undeclared();
});
def(AST_SymbolDeclaration, return_false);
def(AST_Object, function(compressor){
return any(this.properties, compressor);
});

104
test/compress/collapse_vars.js
View File

@@ -2,7 +2,7 @@ collapse_vars_side_effects_1: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1() {
@@ -151,7 +151,7 @@ collapse_vars_issue_721: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
define(["require", "exports", 'handlebars'], function (require, exports, hb) {
@@ -217,7 +217,7 @@ collapse_vars_properties: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1(obj) {
@@ -244,7 +244,7 @@ collapse_vars_if: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1() {
@@ -294,7 +294,7 @@ collapse_vars_while: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:false, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1(y) {
@@ -393,9 +393,9 @@ collapse_vars_do_while: {
}
function f3(y) {
function fn(n) { console.log(n); }
var a = 2;
var a = 2, x = 7;
do {
fn(a = 7);
fn(a = x);
break;
} while (y);
}
@@ -468,8 +468,9 @@ collapse_vars_do_while_drop_assign: {
}
function f3(y) {
function fn(n) { console.log(n); }
var x = 7;
do {
fn(7);
fn(x);
break;
} while (y);
}
@@ -670,7 +671,7 @@ collapse_vars_lvalues: {
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { var w = e1(), v = e2(), c = v = --x; return (w = x) - c; }
function f6(x) { var w = e1(), v = e2(); return (v = --x) - (w = x); }
function f7(x) { var w = e1(), v = e2(), c = v - x; return (w = x) - c; }
function f7(x) { var w = e1(), c = e2() - x; return (w = x) - c; }
function f8(x) { var w = e1(), v = e2(); return (w = x) - (v - x); }
function f9(x) { var w = e1(); return e2() - x - (w = x); }
}
@@ -702,7 +703,7 @@ collapse_vars_lvalues_drop_assign: {
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { var v = (e1(), e2()), c = v = --x; return x - c; }
function f6(x) { e1(), e2(); return --x - x; }
function f7(x) { var v = (e1(), e2()), c = v - x; return x - c; }
function f7(x) { var c = (e1(), e2() - x); return x - c; }
function f8(x) { var v = (e1(), e2()); return x - (v - x); }
function f9(x) { e1(); return e2() - x - x; }
}
@@ -712,7 +713,7 @@ collapse_vars_misc1: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f0(o, a, h) {
@@ -789,7 +790,7 @@ collapse_vars_repeated: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1() {
@@ -812,19 +813,17 @@ collapse_vars_repeated: {
}
expect: {
function f1() {
return -3
return -3;
}
function f2(x) {
return x
return x;
}
(function(x){
var a = "GOOD" + x, e = "BAD", e = a;
console.log(e + "!");
})("!"),
console.log("GOOD!!");
})(),
(function(x){
var a = "GOOD" + x, e = "BAD" + x, e = a;
console.log(e + "!");
})("!");
console.log("GOOD!!");
})();
}
expect_stdout: true
}
@@ -833,7 +832,7 @@ collapse_vars_closures: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function constant_vars_can_be_replaced_in_any_scope() {
@@ -923,7 +922,7 @@ collapse_vars_try: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1() {
@@ -1121,7 +1120,7 @@ collapse_vars_constants: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1(x) {
@@ -1159,7 +1158,7 @@ collapse_vars_arguments: {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
toplevel:true
toplevel:true, reduce_vars:true
}
input: {
var outer = function() {
@@ -1286,6 +1285,7 @@ collapse_vars_regexp: {
join_vars: true,
cascade: true,
side_effects: true,
reduce_vars: true,
}
input: {
function f1() {
@@ -1319,8 +1319,8 @@ collapse_vars_regexp: {
};
}
(function(){
var result, s = "acdabcdeabbb", rx = /ab*/g;
while (result = rx.exec(s))
var result, rx = /ab*/g;
while (result = rx.exec("acdabcdeabbb"))
console.log(result[0]);
})();
}
@@ -1344,7 +1344,10 @@ issue_1537: {
issue_1562: {
options = {
collapse_vars: true,
evaluate: true,
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var v = 1, B = 2;
@@ -1363,14 +1366,11 @@ issue_1562: {
var v = 1;
for (v in objs) f(2);
var x = 3;
while(x + 2) bar(10);
while(5) bar(10);
var y = 4;
do bar(20); while(y + 2);
do bar(20); while(6);
var z = 5;
for (; f(z + 2) ;) bar(30);
for (; f(7) ;) bar(30);
}
}
@@ -1614,3 +1614,43 @@ reduce_vars_assign: {
}
expect_stdout: "0"
}
iife_1: {
options = {
collapse_vars: true,
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var log = function(x) {
console.log(x);
}, foo = bar();
log(foo);
}
expect: {
(function(x) {
console.log(x);
})(bar());
}
}
iife_2: {
options = {
collapse_vars: true,
reduce_vars: false,
toplevel: true,
unused: false,
}
input: {
var foo = bar();
!function(x) {
console.log(x);
}(foo);
}
expect: {
!function(x) {
console.log(x);
}(bar());
}
}