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enhance unused (#3662)

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This commit is contained in:
Alex Lam S.L
2019-12-31 23:39:24 +08:00
committed by GitHub
parent 99ac73a635
commit d83d3d741a
3 changed files with 94 additions and 9 deletions
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15
lib/compress.js
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@@ -3879,7 +3879,7 @@ merge(Compressor.prototype, {
});
return true;
}
return scan_ref_scoped(node, descend);
return scan_ref_scoped(node, descend, true);
});
self.walk(tw);
// pass 2: for every used symbol we need to walk its
@@ -3913,6 +3913,11 @@ merge(Compressor.prototype, {
if (node instanceof AST_Assign) {
if (!in_use || node.left === sym && def.id in fixed_ids && fixed_ids[def.id] !== node) {
value = get_rhs(node);
if (node.write_only) {
value = value.drop_side_effect_free(compressor) || make_node(AST_Number, node, {
value: 0
});
}
}
} else if (!in_use) {
value = make_node(AST_Number, node, {
@@ -4182,7 +4187,7 @@ merge(Compressor.prototype, {
return rhs.right.has_side_effects(compressor) ? rhs : rhs.right;
}
function scan_ref_scoped(node, descend) {
function scan_ref_scoped(node, descend, init) {
var node_def, props = [], sym = assign_as_unused(node, props);
if (sym && self.variables.get(sym.name) === (node_def = sym.definition())) {
props.forEach(function(prop) {
@@ -4191,7 +4196,11 @@ merge(Compressor.prototype, {
if (node instanceof AST_Assign) {
if (node.write_only === "p" && node.right.may_throw_on_access(compressor)) return;
var right = get_rhs(node);
right.walk(tw);
if (init && node.write_only && node_def.scope === self && !right.has_side_effects(compressor)) {
initializations.add(node_def.id, right);
} else {
right.walk(tw);
}
if (node.left === sym) {
if (!node_def.chained && sym.fixed_value(true) === right) {
fixed_ids[node_def.id] = node;