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drop assignment in AST_VarDef.value (#2522)

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fixes #2516
This commit is contained in:
Alex Lam S.L
2017-11-28 13:08:40 +08:00
committed by GitHub
parent b37a68c84f
commit ecc9f6b770
3 changed files with 118 additions and 37 deletions
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59
lib/compress.js
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@@ -1088,6 +1088,7 @@ merge(Compressor.prototype, {
function get_lhs(expr) {
if (expr instanceof AST_VarDef) {
var def = expr.name.definition();
if (!member(expr.name, def.orig)) return;
var declared = def.orig.length - def.eliminated;
var referenced = def.references.length - def.replaced;
if (declared > 1 && !(expr.name instanceof AST_SymbolFunarg)
@@ -2434,47 +2435,18 @@ merge(Compressor.prototype, {
});
return true;
}
var sym;
if (scope === self
&& (sym = assign_as_unused(node)) instanceof AST_SymbolRef
&& self.variables.get(sym.name) === sym.definition()) {
if (node instanceof AST_Assign) node.right.walk(tw);
return true;
}
if (node instanceof AST_SymbolRef) {
var node_def = node.definition();
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
return true;
}
if (node instanceof AST_Scope) {
var save_scope = scope;
scope = node;
descend();
scope = save_scope;
return true;
}
return scan_ref_scoped(node, descend);
});
self.walk(tw);
// pass 2: for every used symbol we need to walk its
// initialization code to figure out if it uses other
// symbols (that may not be in_use).
tw = new TreeWalker(scan_ref_scoped);
for (var i = 0; i < in_use.length; ++i) {
in_use[i].orig.forEach(function(decl){
// undeclared globals will be instanceof AST_SymbolRef
var init = initializations.get(decl.name);
if (init) init.forEach(function(init){
var tw = new TreeWalker(function(node){
if (node instanceof AST_SymbolRef) {
var node_def = node.definition();
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
}
});
init.walk(tw);
});
});
@@ -2663,6 +2635,31 @@ merge(Compressor.prototype, {
}
);
self.transform(tt);
function scan_ref_scoped(node, descend) {
var sym;
if (scope === self
&& (sym = assign_as_unused(node)) instanceof AST_SymbolRef
&& self.variables.get(sym.name) === sym.definition()) {
if (node instanceof AST_Assign) node.right.walk(tw);
return true;
}
if (node instanceof AST_SymbolRef) {
var node_def = node.definition();
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
return true;
}
if (node instanceof AST_Scope) {
var save_scope = scope;
scope = node;
descend();
scope = save_scope;
return true;
}
}
});
AST_Scope.DEFMETHOD("hoist_declarations", function(compressor){