var in_use = [];
var in_use_ids = Object.create(null); // avoid expensive linear scans of in_use
var fixed_ids = Object.create(null);
+ var value_read = Object.create(null);
+ var value_modified = Object.create(null);
if (self instanceof AST_Toplevel && compressor.top_retain) {
self.variables.each(function(def) {
if (compressor.top_retain(def) && !(def.id in in_use_ids)) {
);
self.transform(tt);
+ function verify_safe_usage(def, read, modified) {
+ if (def.id in in_use_ids) return;
+ if (read && modified) {
+ in_use_ids[def.id] = true;
+ in_use.push(def);
+ } else {
+ value_read[def.id] = read;
+ value_modified[def.id] = modified;
+ }
+ }
+
function scan_ref_scoped(node, descend) {
var node_def, props = [], sym = assign_as_unused(node, props);
if (sym instanceof AST_SymbolRef
});
if (node instanceof AST_Assign) {
node.right.walk(tw);
- if (node.left === sym && !node_def.chained && sym.fixed_value() === node.right) {
- fixed_ids[node_def.id] = node;
+ if (node.left === sym) {
+ if (!node_def.chained && sym.fixed_value() === node.right) {
+ fixed_ids[node_def.id] = node;
+ }
+ if (!node.write_only) {
+ verify_safe_usage(node_def, true, value_modified[node_def.id]);
+ }
+ } else {
+ var fixed = sym.fixed_value();
+ if (!fixed || !fixed.is_constant()) {
+ verify_safe_usage(node_def, value_read[node_def.id], true);
+ }
}
}
return true;