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implement function inlining (#2053)

Browse Source 
- empty body
- single `AST_Return`
- single `AST_SimpleStatement`
- avoid `/*#__PURE__*/`

Miscellaneous
- enhance single-use function substitution

fixes #281
This commit is contained in:
Alex Lam S.L
2017-06-06 05:49:53 +08:00
committed by GitHub
parent 27c5284d3d
commit 3493a182b2
11 changed files with 528 additions and 29 deletions
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88
lib/compress.js
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@@ -63,6 +63,7 @@ function Compressor(options, false_by_default) {
hoist_vars : false,
ie8 : false,
if_return : !false_by_default,
inline : !false_by_default,
join_vars : !false_by_default,
keep_fargs : true,
keep_fnames : false,
@@ -2943,24 +2944,9 @@ merge(Compressor.prototype, {
OPT(AST_Call, function(self, compressor){
var exp = self.expression;
if (compressor.option("reduce_vars")
&& exp instanceof AST_SymbolRef) {
var def = exp.definition();
if (compressor.option("reduce_vars") && exp instanceof AST_SymbolRef) {
var fixed = exp.fixed_value();
if (fixed instanceof AST_Defun) {
def.fixed = fixed = make_node(AST_Function, fixed, fixed).clone(true);
}
if (fixed instanceof AST_Function) {
exp = fixed;
if (compressor.option("unused")
&& def.references.length == 1
&& !(def.scope.uses_arguments
&& def.orig[0] instanceof AST_SymbolFunarg)
&& !def.scope.uses_eval
&& compressor.find_parent(AST_Scope) === exp.parent_scope) {
self.expression = exp;
}
}
if (fixed instanceof AST_Function) exp = fixed;
}
if (compressor.option("unused")
&& exp instanceof AST_Function
@@ -3171,13 +3157,61 @@ merge(Compressor.prototype, {
}
}
if (exp instanceof AST_Function) {
if (exp.body[0] instanceof AST_Return) {
var value = exp.body[0].value;
var stat = exp.body[0];
if (compressor.option("inline") && stat instanceof AST_Return) {
var value = stat && stat.value;
if (!value || value.is_constant_expression()) {
var args = self.args.concat(value || make_node(AST_Undefined, self));
return make_sequence(self, args).transform(compressor);
}
}
if (compressor.option("inline")
&& !exp.name
&& exp.body.length == 1
&& !exp.uses_arguments
&& !exp.uses_eval
&& !self.has_pure_annotation(compressor)) {
var body;
if (stat instanceof AST_Return) {
body = stat.value.clone(true);
} else if (stat instanceof AST_SimpleStatement) {
body = [];
merge_sequence(body, stat.body.clone(true));
merge_sequence(body, make_node(AST_Undefined, self));
body = make_sequence(self, body);
}
if (body) {
var fn = exp.clone();
fn.argnames = [];
fn.body = [
make_node(AST_Var, self, {
definitions: exp.argnames.map(function(sym, i) {
return make_node(AST_VarDef, sym, {
name: sym,
value: self.args[i] || make_node(AST_Undefined, self)
});
})
})
];
if (self.args.length > exp.argnames.length) {
fn.body.push(make_node(AST_SimpleStatement, self, {
body: make_sequence(self, self.args.slice(exp.argnames.length))
}));
}
fn.body.push(make_node(AST_Return, self, {
value: body
}));
body = fn.transform(compressor).body;
if (body.length == 0) return make_node(AST_Undefined, self);
if (body.length == 1 && body[0] instanceof AST_Return) {
if (!body[0].value) return make_node(AST_Undefined, self);
body = best_of(compressor, body[0].value, self);
} else {
body = self;
}
if (body !== self) return body;
}
}
if (compressor.option("side_effects") && all(exp.body, is_empty)) {
var args = self.args.concat(make_node(AST_Undefined, self));
return make_sequence(self, args).transform(compressor);
@@ -3836,12 +3870,22 @@ merge(Compressor.prototype, {
return make_node(AST_Infinity, self).optimize(compressor);
}
}
if (compressor.option("evaluate")
&& compressor.option("reduce_vars")
if (compressor.option("reduce_vars")
&& is_lhs(self, compressor.parent()) !== self) {
var d = self.definition();
var fixed = self.fixed_value();
if (fixed) {
if (fixed instanceof AST_Defun) {
d.fixed = fixed = make_node(AST_Function, fixed, fixed).clone(true);
}
if (compressor.option("unused")
&& fixed instanceof AST_Function
&& d.references.length == 1
&& !(d.scope.uses_arguments && d.orig[0] instanceof AST_SymbolFunarg)
&& !d.scope.uses_eval
&& compressor.find_parent(AST_Scope) === fixed.parent_scope) {
return fixed;
}
if (compressor.option("evaluate") && fixed) {
if (d.should_replace === undefined) {
var init = fixed.evaluate(compressor);
if (init !== fixed && (compressor.option("unsafe_regexp") || !(init instanceof RegExp))) {