cerxes/babel
3
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[babel-plugin-transform-es2015-parameters] more oportunities for optimisations

Browse Source
This commit is contained in:
Fabio M. Costa 2015-12-06 18:31:23 -08:00
parent 16ae7c2d9a
commit 3868d36e31
5 changed files with 57 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
packages/babel-plugin-transform-es2015-parameters/src/rest.js
View File

@ -52,19 +52,34 @@ let memberExpressionOptimisationVisitor = {
if (state.noOptimise) {
state.deopted = true;
} else {
if (path.parentPath.isMemberExpression({ computed: true, object: node })) {
// if we know that this member expression is referencing a number then we can safely
// optimise it
let prop = path.parentPath.get("property");
let {parentPath} = path;
// ex: args[0]
if (parentPath.isMemberExpression({ computed: true, object: node })) {
// if we know that this member expression is referencing a number then
// we can safely optimise it
let prop = parentPath.get("property");
if (prop.isBaseType("number")) {
state.candidates.push(path);
return;
}
}
// ex: args.length
if (parentPath.isMemberExpression({ computed: false, object: node })) {
let prop = parentPath.get("property");
if (prop.node.name === "length") {
state.candidates.push(path);
return;
}
}
// we can only do these optimizations if the rest variable would match
// the arguments exactly
// optimise single spread args in calls
if (path.parentPath.isSpreadElement() && state.offset === 0) {
let call = path.parentPath.parentPath;
// ex: fn(...args)
if (state.offset === 0 && parentPath.isSpreadElement()) {
let call = parentPath.parentPath;
if (call.isCallExpression() && call.node.arguments.length === 1) {
state.candidates.push(path);
return;

4
packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-deoptimisation/actual.js vendored
View File

@ -28,3 +28,7 @@ var b = function (foo, ...bar) {
var join = "join";
return bar[join];
};
var b = function (...bar) {
return bar.len;
};

8
packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-deoptimisation/expected.js vendored
View File

@ -53,3 +53,11 @@ var b = function (foo) {
return bar[join];
};
var b = function () {
for (var _len7 = arguments.length, bar = Array(_len7), _key7 = 0; _key7 < _len7; _key7++) {
bar[_key7] = arguments[_key7];
}
return bar.len;
};

16
packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/actual.js vendored
View File

@ -1,9 +1,17 @@
var t = function (...items) {
var x = items[0];
var y = items[1];
var x = items[0];
var y = items[1];
}
function t(...items) {
var x = items[0];
var y = items[1];
var x = items[0];
var y = items[1];
}
function t(...items) {
var a = [];
for (var i = 0; i < items.length; i++) {
a.push(i);
}
return a;
}

16
packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js vendored
View File

@ -1,9 +1,17 @@
var t = function () {
var x = arguments.length <= 0 || arguments[0] === undefined ? undefined : arguments[0];
var y = arguments.length <= 1 || arguments[1] === undefined ? undefined : arguments[1];
var x = arguments.length <= 0 || arguments[0] === undefined ? undefined : arguments[0];
var y = arguments.length <= 1 || arguments[1] === undefined ? undefined : arguments[1];
};
function t() {
var x = arguments.length <= 0 || arguments[0] === undefined ? undefined : arguments[0];
var y = arguments.length <= 1 || arguments[1] === undefined ? undefined : arguments[1];
var x = arguments.length <= 0 || arguments[0] === undefined ? undefined : arguments[0];
var y = arguments.length <= 1 || arguments[1] === undefined ? undefined : arguments[1];
}
function t() {
var a = [];
for (var i = 0; i < arguments.length; i++) {
a.push(i);
}
return a;
}