1 files changed, 204 insertions, 0 deletions
diff --git a/node_modules/webpack/lib/optimize/RemoveParentModulesPlugin.js b/node_modules/webpack/lib/optimize/RemoveParentModulesPlugin.js
new file mode 100644
index 00000000..8c244ec5
--- /dev/null
+++ b/node_modules/webpack/lib/optimize/RemoveParentModulesPlugin.js
@@ -0,0 +1,204 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const { STAGE_BASIC } = require("../OptimizationStages");
+
+/** @typedef {import("../Chunk")} Chunk */
+/** @typedef {import("../ChunkGroup")} ChunkGroup */
+/** @typedef {import("../Compiler")} Compiler */
+/** @typedef {import("../Module")} Module */
+
+/**
+ * Intersects multiple masks represented as bigints
+ * @param {bigint[]} masks The module masks to intersect
+ * @returns {bigint} The intersection of all masks
+ */
+function intersectMasks(masks) {
+	let result = masks[0];
+	for (let i = masks.length - 1; i >= 1; i--) {
+		result &= masks[i];
+	}
+	return result;
+}
+
+const ZERO_BIGINT = BigInt(0);
+const ONE_BIGINT = BigInt(1);
+const THIRTY_TWO_BIGINT = BigInt(32);
+
+/**
+ * Parses the module mask and returns the modules represented by it
+ * @param {bigint} mask the module mask
+ * @param {Module[]} ordinalModules the modules in the order they were added to the mask (LSB is index 0)
+ * @returns {Generator<Module>} the modules represented by the mask
+ */
+function* getModulesFromMask(mask, ordinalModules) {
+	let offset = 31;
+	while (mask !== ZERO_BIGINT) {
+		// Consider the last 32 bits, since that's what Math.clz32 can handle
+		let last32 = Number(BigInt.asUintN(32, mask));
+		while (last32 > 0) {
+			const last = Math.clz32(last32);
+			// The number of trailing zeros is the number trimmed off the input mask + 31 - the number of leading zeros
+			// The 32 is baked into the initial value of offset
+			const moduleIndex = offset - last;
+			// The number of trailing zeros is the index into the array generated by getOrCreateModuleMask
+			const module = ordinalModules[moduleIndex];
+			yield module;
+			// Remove the matched module from the mask
+			// Since we can only count leading zeros, not trailing, we can't just downshift the mask
+			last32 &= ~(1 << (31 - last));
+		}
+
+		// Remove the processed chunk from the mask
+		mask >>= THIRTY_TWO_BIGINT;
+		offset += 32;
+	}
+}
+
+class RemoveParentModulesPlugin {
+	/**
+	 * @param {Compiler} compiler the compiler
+	 * @returns {void}
+	 */
+	apply(compiler) {
+		compiler.hooks.compilation.tap("RemoveParentModulesPlugin", compilation => {
+			/**
+			 * @param {Iterable<Chunk>} chunks the chunks
+			 * @param {ChunkGroup[]} chunkGroups the chunk groups
+			 */
+			const handler = (chunks, chunkGroups) => {
+				const chunkGraph = compilation.chunkGraph;
+				const queue = new Set();
+				const availableModulesMap = new WeakMap();
+
+				let nextModuleMask = ONE_BIGINT;
+				const maskByModule = new WeakMap();
+				/** @type {Module[]} */
+				const ordinalModules = [];
+
+				/**
+				 * Gets or creates a unique mask for a module
+				 * @param {Module} mod the module to get the mask for
+				 * @returns {bigint} the module mask to uniquely identify the module
+				 */
+				const getOrCreateModuleMask = mod => {
+					let id = maskByModule.get(mod);
+					if (id === undefined) {
+						id = nextModuleMask;
+						ordinalModules.push(mod);
+						maskByModule.set(mod, id);
+						nextModuleMask <<= ONE_BIGINT;
+					}
+					return id;
+				};
+
+				// Initialize masks by chunk and by chunk group for quicker comparisons
+				const chunkMasks = new WeakMap();
+				for (const chunk of chunks) {
+					let mask = ZERO_BIGINT;
+					for (const m of chunkGraph.getChunkModulesIterable(chunk)) {
+						const id = getOrCreateModuleMask(m);
+						mask |= id;
+					}
+					chunkMasks.set(chunk, mask);
+				}
+
+				const chunkGroupMasks = new WeakMap();
+				for (const chunkGroup of chunkGroups) {
+					let mask = ZERO_BIGINT;
+					for (const chunk of chunkGroup.chunks) {
+						const chunkMask = chunkMasks.get(chunk);
+						if (chunkMask !== undefined) {
+							mask |= chunkMask;
+						}
+					}
+					chunkGroupMasks.set(chunkGroup, mask);
+				}
+
+				for (const chunkGroup of compilation.entrypoints.values()) {
+					// initialize available modules for chunks without parents
+					availableModulesMap.set(chunkGroup, ZERO_BIGINT);
+					for (const child of chunkGroup.childrenIterable) {
+						queue.add(child);
+					}
+				}
+				for (const chunkGroup of compilation.asyncEntrypoints) {
+					// initialize available modules for chunks without parents
+					availableModulesMap.set(chunkGroup, ZERO_BIGINT);
+					for (const child of chunkGroup.childrenIterable) {
+						queue.add(child);
+					}
+				}
+
+				for (const chunkGroup of queue) {
+					let availableModulesMask = availableModulesMap.get(chunkGroup);
+					let changed = false;
+					for (const parent of chunkGroup.parentsIterable) {
+						const availableModulesInParent = availableModulesMap.get(parent);
+						if (availableModulesInParent !== undefined) {
+							const parentMask =
+								availableModulesInParent | chunkGroupMasks.get(parent);
+							// If we know the available modules in parent: process these
+							if (availableModulesMask === undefined) {
+								// if we have not own info yet: create new entry
+								availableModulesMask = parentMask;
+								changed = true;
+							} else {
+								const newMask = availableModulesMask & parentMask;
+								if (newMask !== availableModulesMask) {
+									changed = true;
+									availableModulesMask = newMask;
+								}
+							}
+						}
+					}
+
+					if (changed) {
+						availableModulesMap.set(chunkGroup, availableModulesMask);
+						// if something changed: enqueue our children
+						for (const child of chunkGroup.childrenIterable) {
+							// Push the child to the end of the queue
+							queue.delete(child);
+							queue.add(child);
+						}
+					}
+				}
+
+				// now we have available modules for every chunk
+				for (const chunk of chunks) {
+					const chunkMask = chunkMasks.get(chunk);
+					if (chunkMask === undefined) continue; // No info about this chunk
+
+					const availableModulesSets = Array.from(
+						chunk.groupsIterable,
+						chunkGroup => availableModulesMap.get(chunkGroup)
+					);
+					if (availableModulesSets.includes(undefined)) continue; // No info about this chunk group
+
+					const availableModulesMask = intersectMasks(availableModulesSets);
+					const toRemoveMask = chunkMask & availableModulesMask;
+					if (toRemoveMask !== ZERO_BIGINT) {
+						for (const module of getModulesFromMask(
+							toRemoveMask,
+							ordinalModules
+						)) {
+							chunkGraph.disconnectChunkAndModule(chunk, module);
+						}
+					}
+				}
+			};
+			compilation.hooks.optimizeChunks.tap(
+				{
+					name: "RemoveParentModulesPlugin",
+					stage: STAGE_BASIC
+				},
+				handler
+			);
+		});
+	}
+}
+module.exports = RemoveParentModulesPlugin;