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fix variable substitution (#1816)

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- let `collapse_vars` take care of value containing any symbols
- improve overhead accounting
This commit is contained in:
Alex Lam S.L
2017-04-16 17:25:39 +08:00
committed by alexlamsl
parent 04b8964505
commit 43ad4e9775
3 changed files with 87 additions and 9 deletions
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38
lib/compress.js
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@@ -3595,7 +3595,9 @@ merge(Compressor.prototype, {
return make_node(AST_Infinity, self).optimize(compressor);
}
}
if (compressor.option("evaluate") && compressor.option("reduce_vars")) {
if (compressor.option("evaluate")
&& compressor.option("reduce_vars")
&& is_lhs(self, compressor.parent()) !== self) {
var d = self.definition();
var fixed = self.fixed_value();
if (fixed) {
@@ -3603,21 +3605,45 @@ merge(Compressor.prototype, {
var init = fixed.evaluate(compressor);
if (init !== fixed) {
init = make_node_from_constant(init, fixed);
var value = best_of_expression(init.optimize(compressor), fixed).print_to_string().length;
var value = 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 = Math.min(value, 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 = d.name.length;
var freq = d.references.length;
var overhead = d.global || !freq ? 0 : (name + 2 + value) / freq;
d.should_replace = value <= name + overhead ? init : false;
var overhead = 0;
if (compressor.option("unused") && (!d.global || compressor.option("toplevel"))) {
overhead = (name + 2 + value) / d.references.length;
}
d.should_replace = value <= name + overhead ? fn : false;
} else {
d.should_replace = false;
}
}
if (d.should_replace) {
return best_of_expression(d.should_replace.optimize(compressor), fixed).clone(true);
return d.should_replace();
}
}
}
return self;
function has_symbol_ref(value) {
var found;
value.walk(new TreeWalker(function(node) {
if (node instanceof AST_SymbolRef) found = true;
if (found) return true;
}));
return found;
}
});
function is_atomic(lhs, self) {