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reduce this within functions

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fixes #2420
This commit is contained in:
alexlamsl 2017-11-02 01:11:06 +08:00
parent a48f87abf2
commit 68d3a1718d
2 changed files with 85 additions and 31 deletions
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74
lib/compress.js
View File

@ -285,7 +285,7 @@ merge(Compressor.prototype, {
self.transform(tt); self.transform(tt);
}); });
AST_Node.DEFMETHOD("reset_opt_flags", function(compressor) { AST_Toplevel.DEFMETHOD("reset_opt_flags", function(compressor) {
var reduce_vars = compressor.option("reduce_vars"); var reduce_vars = compressor.option("reduce_vars");
var unused = compressor.option("unused"); var unused = compressor.option("unused");
// Stack of look-up tables to keep track of whether a `SymbolDef` has been // Stack of look-up tables to keep track of whether a `SymbolDef` has been
@ -564,7 +564,10 @@ merge(Compressor.prototype, {
} }
function is_immutable(value) { function is_immutable(value) {
return value && (value.is_constant() || value instanceof AST_Lambda); if (!value) return false;
return value.is_constant()
|| value instanceof AST_Lambda
|| value instanceof AST_This;
} }
function read_property(obj, key) { function read_property(obj, key) {
@ -4211,39 +4214,48 @@ merge(Compressor.prototype, {
var value = fixed.optimize(compressor); var value = fixed.optimize(compressor);
return value === fixed ? fixed.clone(true) : value; return value === fixed ? fixed.clone(true) : value;
} }
if (compressor.option("evaluate") && fixed) { if (fixed && d.should_replace === undefined) {
if (d.should_replace === undefined) { var init;
var init = fixed.evaluate(compressor); if (fixed instanceof AST_This) {
if (init !== fixed && (compressor.option("unsafe_regexp") || !(init instanceof RegExp))) { if (all(d.references, function(ref) {
init = make_node_from_constant(init, fixed); return d.scope === ref.scope;
var value_length = init.optimize(compressor).print_to_string().length; })) {
var fn; init = fixed;
if (has_symbol_ref(fixed)) { }
fn = function() { } else {
var result = init.optimize(compressor); var ev = fixed.evaluate(compressor);
return result === init ? result.clone(true) : result; if (ev !== fixed && (compressor.option("unsafe_regexp") || !(ev instanceof RegExp))) {
}; init = make_node_from_constant(ev, fixed);
} else {
value_length = Math.min(value_length, fixed.print_to_string().length);
fn = function() {
var result = best_of_expression(init.optimize(compressor), fixed);
return result === init || result === fixed ? result.clone(true) : result;
};
}
var name_length = d.name.length;
var overhead = 0;
if (compressor.option("unused") && !compressor.exposed(d)) {
overhead = (name_length + 2 + value_length) / d.references.length;
}
d.should_replace = value_length <= name_length + overhead ? fn : false;
} else {
d.should_replace = false;
} }
} }
if (d.should_replace) { if (init) {
return d.should_replace(); var value_length = init.optimize(compressor).print_to_string().length;
var fn;
if (has_symbol_ref(fixed)) {
fn = function() {
var result = init.optimize(compressor);
return result === init ? result.clone(true) : result;
};
} else {
value_length = Math.min(value_length, fixed.print_to_string().length);
fn = function() {
var result = best_of_expression(init.optimize(compressor), fixed);
return result === init || result === fixed ? result.clone(true) : result;
};
}
var name_length = d.name.length;
var overhead = 0;
if (compressor.option("unused") && !compressor.exposed(d)) {
overhead = (name_length + 2 + value_length) / d.references.length;
}
d.should_replace = value_length <= name_length + overhead ? fn : false;
} else {
d.should_replace = false;
} }
} }
if (d.should_replace) {
return d.should_replace();
}
} }
return self; return self;

42
test/compress/reduce_vars.js
View File

@ -3295,3 +3295,45 @@ escaped_prop: {
} }
expect_stdout: "2" expect_stdout: "2"
} }
issue_2420: {
options = {
reduce_vars: true,
unused: true,
}
input: {
function run() {
var self = this;
if (self.count++)
self.foo();
else
self.bar();
}
var o = {
count: 0,
foo: function() { console.log("foo"); },
bar: function() { console.log("bar"); },
};
run.call(o);
run.call(o);
}
expect: {
function run() {
if (this.count++)
this.foo();
else
this.bar();
}
var o = {
count: 0,
foo: function() { console.log("foo"); },
bar: function() { console.log("bar"); },
};
run.call(o);
run.call(o);
}
expect_stdout: [
"bar",
"foo",
]
}