improve inline efficiency (#2188)
... by teaching `collapse_vars` some new tricks. fixes #2187
This commit is contained in:
Alex Lam S.L
114
lib/compress.js
114
lib/compress.js
@@ -714,15 +714,23 @@ merge(Compressor.prototype, {
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var candidates = [];
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var stat_index = statements.length;
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while (--stat_index >= 0) {
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// Treat parameters as collapsible in IIFE, i.e.
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// function(a, b){ ... }(x());
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// would be translated into equivalent assignments:
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// var a = x(), b = undefined;
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if (stat_index == 0 && compressor.option("unused")) extract_args();
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// Find collapsible assignments
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extract_candidates(statements[stat_index]);
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while (candidates.length > 0) {
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var candidate = candidates.pop();
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var lhs = get_lhs(candidate);
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if (!lhs || is_lhs_read_only(lhs)) continue;
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// Locate symbols which may execute code outside of scanning range
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var lvalues = get_lvalues(candidate);
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if (lhs instanceof AST_SymbolRef) lvalues[lhs.name] = false;
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var side_effects = value_has_side_effects(candidate);
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var hit = false, abort = false, replaced = false;
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var hit = candidate.name instanceof AST_SymbolFunarg;
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var abort = false, replaced = false;
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var tt = new TreeTransformer(function(node, descend) {
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if (abort) return node;
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// Skip nodes before `candidate` as quickly as possible
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@@ -803,6 +811,35 @@ merge(Compressor.prototype, {
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}
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}
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function extract_args() {
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var iife, fn = compressor.self();
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if (fn instanceof AST_Function
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&& !fn.name
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&& !fn.uses_arguments
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&& !fn.uses_eval
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&& (iife = compressor.parent()) instanceof AST_Call
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&& iife.expression === fn) {
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fn.argnames.forEach(function(sym, i) {
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var arg = iife.args[i];
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if (!arg) arg = make_node(AST_Undefined, sym);
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else arg.walk(new TreeWalker(function(node) {
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if (!arg) return true;
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if (node instanceof AST_SymbolRef && fn.variables.has(node.name)) {
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var s = node.definition().scope;
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if (s !== scope) while (s = s.parent_scope) {
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if (s === scope) return true;
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}
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arg = null;
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}
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}));
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if (arg) candidates.push(make_node(AST_VarDef, sym, {
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name: sym,
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value: arg
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}));
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});
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}
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}
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function extract_candidates(expr) {
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if (expr instanceof AST_Assign && !expr.left.has_side_effects(compressor)
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|| expr instanceof AST_Unary && (expr.operator == "++" || expr.operator == "--")) {
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@@ -823,7 +860,7 @@ merge(Compressor.prototype, {
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function get_lhs(expr) {
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if (expr instanceof AST_VarDef) {
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var def = expr.name.definition();
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if (def.orig.length > 1
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if (def.orig.length > 1 && !(expr.name instanceof AST_SymbolFunarg)
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|| def.references.length == 1 && !compressor.exposed(def)) {
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return make_node(AST_SymbolRef, expr.name, expr.name);
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}
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@@ -3174,69 +3211,42 @@ merge(Compressor.prototype, {
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if (exp instanceof AST_Function) {
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if (compressor.option("inline")
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&& !exp.name
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&& exp.body.length == 1
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&& !exp.uses_arguments
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&& !exp.uses_eval
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&& exp.body.length == 1
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&& all(exp.argnames, function(arg) {
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return arg.__unused;
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})
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&& !self.has_pure_annotation(compressor)) {
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var value;
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if (stat instanceof AST_Return) {
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value = stat.value.clone(true);
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value = stat.value;
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} else if (stat instanceof AST_SimpleStatement) {
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value = make_node(AST_UnaryPrefix, stat, {
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operator: "void",
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expression: stat.body.clone(true)
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expression: stat.body
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});
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}
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if (value) {
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var fn = exp.clone();
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fn.argnames = [];
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fn.body = [];
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if (exp.argnames.length > 0) {
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fn.body.push(make_node(AST_Var, self, {
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definitions: exp.argnames.map(function(sym, i) {
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var arg = self.args[i];
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return make_node(AST_VarDef, sym, {
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name: sym,
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value: arg ? arg.clone(true) : make_node(AST_Undefined, self)
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});
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})
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}));
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}
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if (self.args.length > exp.argnames.length) {
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fn.body.push(make_node(AST_SimpleStatement, self, {
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body: make_sequence(self, self.args.slice(exp.argnames.length).map(function(node) {
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return node.clone(true);
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}))
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}));
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}
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fn.body.push(make_node(AST_Return, self, {
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value: value
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}));
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var body = fn.transform(compressor).body;
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if (body.length == 0) return make_node(AST_Undefined, self);
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if (body.length == 1 && body[0] instanceof AST_Return) {
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value = body[0].value;
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if (!value) return make_node(AST_Undefined, self);
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var tw = new TreeWalker(function(node) {
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if (value === self) return true;
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if (node instanceof AST_SymbolRef) {
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var ref = node.scope.find_variable(node);
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if (ref && ref.scope.parent_scope === fn.parent_scope) {
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value = self;
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return true;
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}
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}
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if (node instanceof AST_This && !tw.find_parent(AST_Scope)) {
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value = self;
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var tw = new TreeWalker(function(node) {
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if (!value) return true;
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if (node instanceof AST_SymbolRef) {
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var ref = node.scope.find_variable(node);
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if (ref && ref.scope.parent_scope === fn.parent_scope) {
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value = null;
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return true;
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}
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});
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value.walk(tw);
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if (value !== self) value = best_of(compressor, value, self);
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} else {
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value = self;
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}
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if (value !== self) return value;
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}
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if (node instanceof AST_This && !tw.find_parent(AST_Scope)) {
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value = null;
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return true;
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}
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});
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value.walk(tw);
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}
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if (value) {
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var args = self.args.concat(value);
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return make_sequence(self, args).transform(compressor);
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}
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}
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if (compressor.option("side_effects") && all(exp.body, is_empty)) {
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