Merge pull request webpack#6613 from brentwilton/improve-performance-of-module-concatenation-plugin

sokra · web-flow · commit 2e687d0f0672 · 2018-03-03T17:37:38.000+01:00
improve performance of ModuleConcatenationPlugin for loop
diff --git a/lib/optimize/ModuleConcatenationPlugin.js b/lib/optimize/ModuleConcatenationPlugin.js
@@ -281,9 +281,16 @@ class ModuleConcatenationPlugin {
 							for (const reason of newModule.reasons) {
 								reason.dependency.module = newModule;
 							}
-							for (const dep of newModule.dependencies) {
+							// TODO: remove when LTS node version contains fixed v8 version
+							// @see https://github.com/webpack/webpack/pull/6613
+							// Turbofan does not correctly inline for-of loops with polymorphic input arrays.
+							// Work around issue by using a standard for loop and assigning dep.module.reasons
+							for (let i = 0; i < newModule.dependencies.length; i++) {
+								let dep = newModule.dependencies[i];
 								if (dep.module) {
-									for (const reason of dep.module.reasons) {
+									let reasons = dep.module.reasons;
+									for (let j = 0; j < reasons.length; j++) {
+										let reason = reasons[j];
 										if (reason.dependency === dep) reason.module = newModule;
 									}
 								}

Original file line number	Diff line number	Diff line change
`@@ -281,9 +281,16 @@ class ModuleConcatenationPlugin {`
`281`	`281`	`for (const reason of newModule.reasons) {`
`282`	`282`	`reason.dependency.module = newModule;`
`283`	`283`	`}`
`284`		`- for (const dep of newModule.dependencies) {`
	`284`	`+ // TODO: remove when LTS node version contains fixed v8 version`
	`285`	`+ // @see https://github.com/webpack/webpack/pull/6613`
	`286`	`+ // Turbofan does not correctly inline for-of loops with polymorphic input arrays.`
	`287`	`+ // Work around issue by using a standard for loop and assigning dep.module.reasons`
	`288`	`+ for (let i = 0; i < newModule.dependencies.length; i++) {`
	`289`	`+ let dep = newModule.dependencies[i];`
`285`	`290`	`if (dep.module) {`
`286`		`- for (const reason of dep.module.reasons) {`
	`291`	`+ let reasons = dep.module.reasons;`
	`292`	`+ for (let j = 0; j < reasons.length; j++) {`
	`293`	`+ let reason = reasons[j];`
`287`	`294`	`if (reason.dependency === dep) reason.module = newModule;`
`288`	`295`	`}`
`289`	`296`	`}`