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perform reduce_vars on safe literals (#2351)

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- constant expression
- single reference
- same scope
- not across loop body
This commit is contained in:
Alex Lam S.L
2017-10-09 12:25:06 +08:00
committed by GitHub
parent 1abe14296e
commit b810e2f8da
5 changed files with 286 additions and 36 deletions
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59
lib/compress.js
View File

@@ -297,6 +297,8 @@ merge(Compressor.prototype, {
if (node instanceof AST_SymbolRef) d.references.push(node);
d.fixed = false;
});
var in_loop = null;
var loop_ids = Object.create(null);
var tw = new TreeWalker(function(node, descend) {
node._squeezed = false;
node._optimized = false;
@@ -307,7 +309,7 @@ merge(Compressor.prototype, {
var d = node.definition();
d.references.push(node);
if (d.fixed === undefined || !safe_to_read(d)
|| is_modified(node, 0, is_immutable(node.fixed_value()))) {
|| is_modified(node, 0, is_immutable(node))) {
d.fixed = false;
} else {
var parent = tw.parent();
@@ -329,6 +331,7 @@ merge(Compressor.prototype, {
d.fixed = function() {
return node.value;
};
loop_ids[d.id] = in_loop;
mark(d, false);
descend();
} else {
@@ -384,6 +387,7 @@ merge(Compressor.prototype, {
d.fixed = function() {
return iife.args[i] || make_node(AST_Undefined, iife);
};
loop_ids[d.id] = in_loop;
mark(d, true);
} else {
d.fixed = false;
@@ -431,10 +435,13 @@ merge(Compressor.prototype, {
return true;
}
if (node instanceof AST_DWLoop) {
var saved_loop = in_loop;
in_loop = node;
push();
node.condition.walk(tw);
node.body.walk(tw);
pop();
in_loop = saved_loop;
return true;
}
if (node instanceof AST_LabeledStatement) {
@@ -445,6 +452,8 @@ merge(Compressor.prototype, {
}
if (node instanceof AST_For) {
if (node.init) node.init.walk(tw);
var saved_loop = in_loop;
in_loop = node;
if (node.condition) {
push();
node.condition.walk(tw);
@@ -458,14 +467,18 @@ merge(Compressor.prototype, {
node.step.walk(tw);
pop();
}
in_loop = saved_loop;
return true;
}
if (node instanceof AST_ForIn) {
node.init.walk(suppressor);
node.object.walk(tw);
var saved_loop = in_loop;
in_loop = node;
push();
node.body.walk(tw);
pop();
in_loop = saved_loop;
return true;
}
if (node instanceof AST_Try) {
@@ -535,10 +548,23 @@ merge(Compressor.prototype, {
}
def.references = [];
def.should_replace = undefined;
def.single_use = undefined;
}
function is_immutable(value) {
return value && value.is_constant() || value instanceof AST_Lambda;
function is_immutable(node) {
var value = node.fixed_value();
if (!value) return false;
if (value.is_constant()) return true;
if (compressor.option("unused")) {
var d = node.definition();
if (d.single_use === undefined) {
d.single_use = loop_ids[d.id] === in_loop
&& d.scope === node.scope
&& value.is_constant_expression();
}
if (d.references.length == 1 && d.single_use) return true;
}
return value instanceof AST_Lambda;
}
function is_modified(node, level, immutable) {
@@ -2115,6 +2141,22 @@ merge(Compressor.prototype, {
}
def(AST_Node, return_false);
def(AST_Constant, return_true);
def(AST_Function, function(){
var self = this;
var result = true;
self.walk(new TreeWalker(function(node) {
if (!result) return true;
if (node instanceof AST_SymbolRef) {
var def = node.definition();
if (self.enclosed.indexOf(def) >= 0
&& self.variables.get(def.name) !== def) {
result = false;
return true;
}
}
}));
return result;
});
def(AST_Unary, function(){
return this.expression.is_constant_expression();
});
@@ -4078,12 +4120,13 @@ merge(Compressor.prototype, {
d.fixed = fixed = make_node(AST_Function, fixed, fixed);
}
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.clone(true);
&& (d.single_use || fixed instanceof AST_Function
&& !(d.scope.uses_arguments && d.orig[0] instanceof AST_SymbolFunarg)
&& !d.scope.uses_eval
&& compressor.find_parent(AST_Scope) === fixed.parent_scope)) {
var value = fixed.optimize(compressor);
return value === fixed ? fixed.clone(true) : value;
}
if (compressor.option("evaluate") && fixed) {
if (d.should_replace === undefined) {

44
test/compress/collapse_vars.js
View File

@@ -1268,22 +1268,21 @@ collapse_vars_short_circuited_conditions: {
collapse_vars_regexp: {
options = {
collapse_vars: true,
loops: false,
sequences: true,
dead_code: true,
conditionals: true,
comparisons: true,
evaluate: true,
booleans: true,
unused: true,
hoist_funs: true,
keep_fargs: true,
cascade: true,
collapse_vars: true,
comparisons: true,
conditionals: true,
dead_code: true,
evaluate: true,
if_return: true,
join_vars: true,
cascade: true,
side_effects: true,
hoist_funs: true,
keep_fargs: true,
loops: false,
reduce_vars: true,
side_effects: true,
unused: true,
}
input: {
function f1() {
@@ -1292,12 +1291,12 @@ collapse_vars_regexp: {
return [rx, k];
}
function f2() {
var rx = /[abc123]+/;
var rx = /ab*/g;
return function(s) {
return rx.exec(s);
};
}
(function(){
(function() {
var result;
var s = 'acdabcdeabbb';
var rx = /ab*/g;
@@ -1305,22 +1304,35 @@ collapse_vars_regexp: {
console.log(result[0]);
}
})();
(function() {
var result;
var s = 'acdabcdeabbb';
var rx = f2();
while (result = rx(s)) {
console.log(result[0]);
}
})();
}
expect: {
function f1() {
return [/[A-Z]+/, 9];
}
function f2() {
var rx = /[abc123]+/;
var rx = /ab*/g;
return function(s) {
return rx.exec(s);
};
}
(function(){
(function() {
var result, rx = /ab*/g;
while (result = rx.exec("acdabcdeabbb"))
console.log(result[0]);
})();
(function() {
var result, rx = f2();
while (result = rx("acdabcdeabbb"))
console.log(result[0]);
})();
}
expect_stdout: true
}

12
test/compress/drop-unused.js
View File

@@ -751,12 +751,12 @@ issue_1583: {
expect: {
function m(t) {
(function(e) {
t = e();
})(function() {
return (function(a) {
return a;
})(function(a) {});
});
t = function() {
return (function(a) {
return function(a) {};
})();
}();
})();
}
}
}

14
test/compress/evaluate.js
View File

@@ -1021,6 +1021,7 @@ issue_1964_1: {
input: {
function f() {
var long_variable_name = /\s/;
console.log(long_variable_name.source);
return "a b c".split(long_variable_name)[1];
}
console.log(f());
@@ -1028,11 +1029,15 @@ issue_1964_1: {
expect: {
function f() {
var long_variable_name = /\s/;
console.log(long_variable_name.source);
return "a b c".split(long_variable_name)[1];
}
console.log(f());
}
expect_stdout: "b"
expect_stdout: [
"\\s",
"b",
]
}
issue_1964_2: {
@@ -1045,17 +1050,22 @@ issue_1964_2: {
input: {
function f() {
var long_variable_name = /\s/;
console.log(long_variable_name.source);
return "a b c".split(long_variable_name)[1];
}
console.log(f());
}
expect: {
function f() {
console.log(/\s/.source);
return "a b c".split(/\s/)[1];
}
console.log(f());
}
expect_stdout: "b"
expect_stdout: [
"\\s",
"b",
]
}
array_slice_index: {

193
test/compress/reduce_vars.js
View File

@@ -172,6 +172,7 @@ unsafe_evaluate: {
options = {
evaluate : true,
reduce_vars : true,
side_effects : true,
unsafe : true,
unused : true
}
@@ -1898,10 +1899,7 @@ redefine_farg_3: {
console.log(f([]), g([]), h([]));
}
expect: {
console.log(function(a) {
var a;
return typeof a;
}([]), "number", "undefined");
console.log(typeof [], "number", "undefined");
}
expect_stdout: "object number undefined"
}
@@ -2629,3 +2627,190 @@ for_in_prop: {
}
expect_stdout: "1"
}
obj_var_1: {
options = {
evaluate: true,
passes: 2,
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var C = 1;
var obj = {
bar: function() {
return C + C;
}
};
console.log(obj.bar());
}
expect: {
console.log({
bar: function() {
return 2;
}
}.bar());
}
expect_stdout: "2"
}
obj_var_2: {
options = {
evaluate: true,
inline: true,
passes: 2,
reduce_vars: true,
side_effects: true,
toplevel: true,
unsafe: true,
unused: true,
}
input: {
var C = 1;
var obj = {
bar: function() {
return C + C;
}
};
console.log(obj.bar());
}
expect: {
console.log(2);
}
expect_stdout: "2"
}
obj_arg_1: {
options = {
evaluate: true,
inline: true,
passes: 2,
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var C = 1;
function f(obj) {
return obj.bar();
}
console.log(f({
bar: function() {
return C + C;
}
}));
}
expect: {
console.log({
bar: function() {
return 2;
}
}.bar());
}
expect_stdout: "2"
}
obj_arg_2: {
options = {
evaluate: true,
inline: true,
passes: 2,
reduce_vars: true,
side_effects: true,
toplevel: true,
unsafe: true,
unused: true,
}
input: {
var C = 1;
function f(obj) {
return obj.bar();
}
console.log(f({
bar: function() {
return C + C;
}
}));
}
expect: {
console.log(2);
}
expect_stdout: "2"
}
func_arg_1: {
options = {
evaluate: true,
inline: true,
passes: 2,
reduce_vars: true,
side_effects: true,
toplevel: true,
unused: true,
}
input: {
var a = 42;
!function(a) {
console.log(a());
}(function() {
return a;
});
}
expect: {
console.log(42);
}
expect_stdout: "42"
}
func_arg_2: {
options = {
evaluate: true,
inline: true,
passes: 2,
reduce_vars: true,
side_effects: true,
toplevel: true,
unused: true,
}
input: {
var a = 42;
!function(a) {
console.log(a());
}(function(a) {
return a;
});
}
expect: {
console.log(void 0);
}
expect_stdout: "undefined"
}
regex_loop: {
options = {
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
function f(x) {
for (var r, s = "acdabcdeabbb"; r = x().exec(s);)
console.log(r[0]);
}
var a = /ab*/g;
f(function() {
return a;
});
}
expect: {
var a = /ab*/g;
(function(x) {
for (var r, s = "acdabcdeabbb"; r = x().exec(s);)
console.log(r[0]);
})(function() {
return a;
});
}
expect_stdout: true
}