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691 lines
24 KiB
C++
691 lines
24 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* vim: set ts=8 sts=2 et sw=2 tw=80:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef js_UbiNodeDominatorTree_h
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#define js_UbiNodeDominatorTree_h
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#include "mozilla/Attributes.h"
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#include "mozilla/DebugOnly.h"
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#include "mozilla/Maybe.h"
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#include "mozilla/Move.h"
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#include "mozilla/UniquePtr.h"
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#include "js/AllocPolicy.h"
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#include "js/UbiNode.h"
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#include "js/UbiNodePostOrder.h"
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#include "js/Utility.h"
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#include "js/Vector.h"
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namespace JS {
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namespace ubi {
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/**
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* In a directed graph with a root node `R`, a node `A` is said to "dominate" a
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* node `B` iff every path from `R` to `B` contains `A`. A node `A` is said to
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* be the "immediate dominator" of a node `B` iff it dominates `B`, is not `B`
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* itself, and does not dominate any other nodes which also dominate `B` in
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* turn.
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*
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* If we take every node from a graph `G` and create a new graph `T` with edges
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* to each node from its immediate dominator, then `T` is a tree (each node has
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* only one immediate dominator, or none if it is the root). This tree is called
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* a "dominator tree".
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*
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* This class represents a dominator tree constructed from a `JS::ubi::Node`
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* heap graph. The domination relationship and dominator trees are useful tools
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* for analyzing heap graphs because they tell you:
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*
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* - Exactly what could be reclaimed by the GC if some node `A` became
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* unreachable: those nodes which are dominated by `A`,
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*
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* - The "retained size" of a node in the heap graph, in contrast to its
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* "shallow size". The "shallow size" is the space taken by a node itself,
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* not counting anything it references. The "retained size" of a node is its
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* shallow size plus the size of all the things that would be collected if
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* the original node wasn't (directly or indirectly) referencing them. In
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* other words, the retained size is the shallow size of a node plus the
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* shallow sizes of every other node it dominates. For example, the root
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* node in a binary tree might have a small shallow size that does not take
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* up much space itself, but it dominates the rest of the binary tree and
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* its retained size is therefore significant (assuming no external
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* references into the tree).
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*
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* The simple, engineered algorithm presented in "A Simple, Fast Dominance
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* Algorithm" by Cooper el al[0] is used to find dominators and construct the
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* dominator tree. This algorithm runs in O(n^2) time, but is faster in practice
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* than alternative algorithms with better theoretical running times, such as
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* Lengauer-Tarjan which runs in O(e * log(n)). The big caveat to that statement
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* is that Cooper et al found it is faster in practice *on control flow graphs*
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* and I'm not convinced that this property also holds on *heap* graphs. That
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* said, the implementation of this algorithm is *much* simpler than
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* Lengauer-Tarjan and has been found to be fast enough at least for the time
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* being.
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*
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* [0]: http://www.cs.rice.edu/~keith/EMBED/dom.pdf
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*/
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class JS_PUBLIC_API DominatorTree {
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private:
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// Types.
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using PredecessorSets = js::HashMap<Node, NodeSetPtr, js::DefaultHasher<Node>,
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js::SystemAllocPolicy>;
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using NodeToIndexMap = js::HashMap<Node, uint32_t, js::DefaultHasher<Node>,
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js::SystemAllocPolicy>;
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class DominatedSets;
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public:
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class DominatedSetRange;
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/**
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* A pointer to an immediately dominated node.
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*
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* Don't use this type directly; it is no safer than regular pointers. This
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* is only for use indirectly with range-based for loops and
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* `DominatedSetRange`.
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*
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* @see JS::ubi::DominatorTree::getDominatedSet
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*/
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class DominatedNodePtr {
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friend class DominatedSetRange;
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const JS::ubi::Vector<Node>& postOrder;
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const uint32_t* ptr;
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DominatedNodePtr(const JS::ubi::Vector<Node>& postOrder,
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const uint32_t* ptr)
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: postOrder(postOrder), ptr(ptr) {}
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public:
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bool operator!=(const DominatedNodePtr& rhs) const {
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return ptr != rhs.ptr;
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}
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void operator++() { ptr++; }
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const Node& operator*() const { return postOrder[*ptr]; }
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};
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/**
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* A range of immediately dominated `JS::ubi::Node`s for use with
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* range-based for loops.
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*
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* @see JS::ubi::DominatorTree::getDominatedSet
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*/
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class DominatedSetRange {
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friend class DominatedSets;
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const JS::ubi::Vector<Node>& postOrder;
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const uint32_t* beginPtr;
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const uint32_t* endPtr;
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DominatedSetRange(JS::ubi::Vector<Node>& postOrder, const uint32_t* begin,
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const uint32_t* end)
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: postOrder(postOrder), beginPtr(begin), endPtr(end) {
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MOZ_ASSERT(begin <= end);
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}
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public:
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DominatedNodePtr begin() const {
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MOZ_ASSERT(beginPtr <= endPtr);
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return DominatedNodePtr(postOrder, beginPtr);
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}
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DominatedNodePtr end() const { return DominatedNodePtr(postOrder, endPtr); }
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size_t length() const {
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MOZ_ASSERT(beginPtr <= endPtr);
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return endPtr - beginPtr;
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}
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/**
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* Safely skip ahead `n` dominators in the range, in O(1) time.
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*
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* Example usage:
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*
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* mozilla::Maybe<DominatedSetRange> range =
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* myDominatorTree.getDominatedSet(myNode);
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* if (range.isNothing()) {
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* // Handle unknown nodes however you see fit...
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* return false;
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* }
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*
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* // Don't care about the first ten, for whatever reason.
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* range->skip(10);
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* for (const JS::ubi::Node& dominatedNode : *range) {
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* // ...
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* }
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*/
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void skip(size_t n) {
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beginPtr += n;
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if (beginPtr > endPtr) {
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beginPtr = endPtr;
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}
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}
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};
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private:
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/**
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* The set of all dominated sets in a dominator tree.
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*
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* Internally stores the sets in a contiguous array, with a side table of
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* indices into that contiguous array to denote the start index of each
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* individual set.
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*/
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class DominatedSets {
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JS::ubi::Vector<uint32_t> dominated;
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JS::ubi::Vector<uint32_t> indices;
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DominatedSets(JS::ubi::Vector<uint32_t>&& dominated,
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JS::ubi::Vector<uint32_t>&& indices)
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: dominated(std::move(dominated)), indices(std::move(indices)) {}
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public:
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// DominatedSets is not copy-able.
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DominatedSets(const DominatedSets& rhs) = delete;
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DominatedSets& operator=(const DominatedSets& rhs) = delete;
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// DominatedSets is move-able.
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DominatedSets(DominatedSets&& rhs)
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: dominated(std::move(rhs.dominated)), indices(std::move(rhs.indices)) {
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MOZ_ASSERT(this != &rhs, "self-move not allowed");
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}
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DominatedSets& operator=(DominatedSets&& rhs) {
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this->~DominatedSets();
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new (this) DominatedSets(std::move(rhs));
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return *this;
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}
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/**
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* Create the DominatedSets given the mapping of a node index to its
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* immediate dominator. Returns `Some` on success, `Nothing` on OOM
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* failure.
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*/
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static mozilla::Maybe<DominatedSets> Create(
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const JS::ubi::Vector<uint32_t>& doms) {
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auto length = doms.length();
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MOZ_ASSERT(length < UINT32_MAX);
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// Create a vector `dominated` holding a flattened set of buckets of
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// immediately dominated children nodes, with a lookup table
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// `indices` mapping from each node to the beginning of its bucket.
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//
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// This has three phases:
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//
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// 1. Iterate over the full set of nodes and count up the size of
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// each bucket. These bucket sizes are temporarily stored in the
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// `indices` vector.
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//
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// 2. Convert the `indices` vector to store the cumulative sum of
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// the sizes of all buckets before each index, resulting in a
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// mapping from node index to one past the end of that node's
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// bucket.
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//
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// 3. Iterate over the full set of nodes again, filling in bucket
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// entries from the end of the bucket's range to its
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// beginning. This decrements each index as a bucket entry is
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// filled in. After having filled in all of a bucket's entries,
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// the index points to the start of the bucket.
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JS::ubi::Vector<uint32_t> dominated;
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JS::ubi::Vector<uint32_t> indices;
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if (!dominated.growBy(length) || !indices.growBy(length)) {
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return mozilla::Nothing();
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}
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// 1
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memset(indices.begin(), 0, length * sizeof(uint32_t));
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for (uint32_t i = 0; i < length; i++) {
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indices[doms[i]]++;
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}
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// 2
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uint32_t sumOfSizes = 0;
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for (uint32_t i = 0; i < length; i++) {
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sumOfSizes += indices[i];
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MOZ_ASSERT(sumOfSizes <= length);
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indices[i] = sumOfSizes;
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}
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// 3
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for (uint32_t i = 0; i < length; i++) {
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auto idxOfDom = doms[i];
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indices[idxOfDom]--;
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dominated[indices[idxOfDom]] = i;
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}
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#ifdef DEBUG
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// Assert that our buckets are non-overlapping and don't run off the
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// end of the vector.
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uint32_t lastIndex = 0;
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for (uint32_t i = 0; i < length; i++) {
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MOZ_ASSERT(indices[i] >= lastIndex);
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MOZ_ASSERT(indices[i] < length);
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lastIndex = indices[i];
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}
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#endif
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return mozilla::Some(
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DominatedSets(std::move(dominated), std::move(indices)));
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}
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/**
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* Get the set of nodes immediately dominated by the node at
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* `postOrder[nodeIndex]`.
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*/
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DominatedSetRange dominatedSet(JS::ubi::Vector<Node>& postOrder,
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uint32_t nodeIndex) const {
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MOZ_ASSERT(postOrder.length() == indices.length());
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MOZ_ASSERT(nodeIndex < indices.length());
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auto end = nodeIndex == indices.length() - 1
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? dominated.end()
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: &dominated[indices[nodeIndex + 1]];
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return DominatedSetRange(postOrder, &dominated[indices[nodeIndex]], end);
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}
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};
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private:
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// Data members.
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JS::ubi::Vector<Node> postOrder;
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NodeToIndexMap nodeToPostOrderIndex;
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JS::ubi::Vector<uint32_t> doms;
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DominatedSets dominatedSets;
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mozilla::Maybe<JS::ubi::Vector<JS::ubi::Node::Size>> retainedSizes;
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private:
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// We use `UNDEFINED` as a sentinel value in the `doms` vector to signal
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// that we haven't found any dominators for the node at the corresponding
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// index in `postOrder` yet.
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static const uint32_t UNDEFINED = UINT32_MAX;
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DominatorTree(JS::ubi::Vector<Node>&& postOrder,
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NodeToIndexMap&& nodeToPostOrderIndex,
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JS::ubi::Vector<uint32_t>&& doms, DominatedSets&& dominatedSets)
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: postOrder(std::move(postOrder)),
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nodeToPostOrderIndex(std::move(nodeToPostOrderIndex)),
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doms(std::move(doms)),
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dominatedSets(std::move(dominatedSets)),
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retainedSizes(mozilla::Nothing()) {}
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static uint32_t intersect(JS::ubi::Vector<uint32_t>& doms, uint32_t finger1,
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uint32_t finger2) {
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while (finger1 != finger2) {
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if (finger1 < finger2) {
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finger1 = doms[finger1];
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} else if (finger2 < finger1) {
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finger2 = doms[finger2];
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}
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}
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return finger1;
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}
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// Do the post order traversal of the heap graph and populate our
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// predecessor sets.
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static MOZ_MUST_USE bool doTraversal(JSContext* cx, AutoCheckCannotGC& noGC,
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const Node& root,
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JS::ubi::Vector<Node>& postOrder,
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PredecessorSets& predecessorSets) {
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uint32_t nodeCount = 0;
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auto onNode = [&](const Node& node) {
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nodeCount++;
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if (MOZ_UNLIKELY(nodeCount == UINT32_MAX)) {
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return false;
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}
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return postOrder.append(node);
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};
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auto onEdge = [&](const Node& origin, const Edge& edge) {
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auto p = predecessorSets.lookupForAdd(edge.referent);
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if (!p) {
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mozilla::UniquePtr<NodeSet, DeletePolicy<NodeSet>> set(
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js_new<NodeSet>());
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if (!set || !predecessorSets.add(p, edge.referent, std::move(set))) {
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return false;
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}
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}
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MOZ_ASSERT(p && p->value());
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return p->value()->put(origin);
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};
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PostOrder traversal(cx, noGC);
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return traversal.addStart(root) && traversal.traverse(onNode, onEdge);
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}
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// Populates the given `map` with an entry for each node to its index in
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// `postOrder`.
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static MOZ_MUST_USE bool mapNodesToTheirIndices(
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JS::ubi::Vector<Node>& postOrder, NodeToIndexMap& map) {
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MOZ_ASSERT(map.empty());
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MOZ_ASSERT(postOrder.length() < UINT32_MAX);
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uint32_t length = postOrder.length();
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if (!map.reserve(length)) {
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return false;
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}
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for (uint32_t i = 0; i < length; i++) {
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map.putNewInfallible(postOrder[i], i);
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}
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return true;
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}
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// Convert the Node -> NodeSet predecessorSets to a index -> Vector<index>
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// form.
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static MOZ_MUST_USE bool convertPredecessorSetsToVectors(
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const Node& root, JS::ubi::Vector<Node>& postOrder,
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PredecessorSets& predecessorSets, NodeToIndexMap& nodeToPostOrderIndex,
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JS::ubi::Vector<JS::ubi::Vector<uint32_t>>& predecessorVectors) {
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MOZ_ASSERT(postOrder.length() < UINT32_MAX);
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uint32_t length = postOrder.length();
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MOZ_ASSERT(predecessorVectors.length() == 0);
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if (!predecessorVectors.growBy(length)) {
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return false;
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}
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for (uint32_t i = 0; i < length - 1; i++) {
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auto& node = postOrder[i];
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MOZ_ASSERT(node != root,
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"Only the last node should be root, since this was a post "
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"order traversal.");
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auto ptr = predecessorSets.lookup(node);
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MOZ_ASSERT(ptr,
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"Because this isn't the root, it had better have "
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"predecessors, or else how "
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"did we even find it.");
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auto& predecessors = ptr->value();
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if (!predecessorVectors[i].reserve(predecessors->count())) {
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return false;
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}
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for (auto range = predecessors->all(); !range.empty(); range.popFront()) {
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auto ptr = nodeToPostOrderIndex.lookup(range.front());
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MOZ_ASSERT(ptr);
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predecessorVectors[i].infallibleAppend(ptr->value());
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}
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}
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predecessorSets.clearAndCompact();
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return true;
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}
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// Initialize `doms` such that the immediate dominator of the `root` is the
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// `root` itself and all others are `UNDEFINED`.
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static MOZ_MUST_USE bool initializeDominators(JS::ubi::Vector<uint32_t>& doms,
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uint32_t length) {
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MOZ_ASSERT(doms.length() == 0);
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if (!doms.growByUninitialized(length)) {
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return false;
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}
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doms[length - 1] = length - 1;
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for (uint32_t i = 0; i < length - 1; i++) {
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doms[i] = UNDEFINED;
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}
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return true;
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}
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void assertSanity() const {
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MOZ_ASSERT(postOrder.length() == doms.length());
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MOZ_ASSERT(postOrder.length() == nodeToPostOrderIndex.count());
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MOZ_ASSERT_IF(retainedSizes.isSome(),
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postOrder.length() == retainedSizes->length());
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}
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MOZ_MUST_USE bool computeRetainedSizes(mozilla::MallocSizeOf mallocSizeOf) {
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MOZ_ASSERT(retainedSizes.isNothing());
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auto length = postOrder.length();
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retainedSizes.emplace();
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if (!retainedSizes->growBy(length)) {
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retainedSizes = mozilla::Nothing();
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return false;
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}
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// Iterate in forward order so that we know all of a node's children in
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// the dominator tree have already had their retained size
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// computed. Then we can simply say that the retained size of a node is
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// its shallow size (JS::ubi::Node::size) plus the retained sizes of its
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// immediate children in the tree.
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for (uint32_t i = 0; i < length; i++) {
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auto size = postOrder[i].size(mallocSizeOf);
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for (const auto& dominated : dominatedSets.dominatedSet(postOrder, i)) {
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// The root node dominates itself, but shouldn't contribute to
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// its own retained size.
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if (dominated == postOrder[length - 1]) {
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MOZ_ASSERT(i == length - 1);
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continue;
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}
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auto ptr = nodeToPostOrderIndex.lookup(dominated);
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MOZ_ASSERT(ptr);
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auto idxOfDominated = ptr->value();
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MOZ_ASSERT(idxOfDominated < i);
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size += retainedSizes.ref()[idxOfDominated];
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}
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retainedSizes.ref()[i] = size;
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}
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return true;
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}
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public:
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// DominatorTree is not copy-able.
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DominatorTree(const DominatorTree&) = delete;
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DominatorTree& operator=(const DominatorTree&) = delete;
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// DominatorTree is move-able.
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DominatorTree(DominatorTree&& rhs)
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: postOrder(std::move(rhs.postOrder)),
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nodeToPostOrderIndex(std::move(rhs.nodeToPostOrderIndex)),
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doms(std::move(rhs.doms)),
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dominatedSets(std::move(rhs.dominatedSets)),
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retainedSizes(std::move(rhs.retainedSizes)) {
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MOZ_ASSERT(this != &rhs, "self-move is not allowed");
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}
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DominatorTree& operator=(DominatorTree&& rhs) {
|
|
this->~DominatorTree();
|
|
new (this) DominatorTree(std::move(rhs));
|
|
return *this;
|
|
}
|
|
|
|
/**
|
|
* Construct a `DominatorTree` of the heap graph visible from `root`. The
|
|
* `root` is also used as the root of the resulting dominator tree.
|
|
*
|
|
* The resulting `DominatorTree` instance must not outlive the
|
|
* `JS::ubi::Node` graph it was constructed from.
|
|
*
|
|
* - For `JS::ubi::Node` graphs backed by the live heap graph, this means
|
|
* that the `DominatorTree`'s lifetime _must_ be contained within the
|
|
* scope of the provided `AutoCheckCannotGC` reference because a GC will
|
|
* invalidate the nodes.
|
|
*
|
|
* - For `JS::ubi::Node` graphs backed by some other offline structure
|
|
* provided by the embedder, the resulting `DominatorTree`'s lifetime is
|
|
* bounded by that offline structure's lifetime.
|
|
*
|
|
* In practice, this means that within SpiderMonkey we must treat
|
|
* `DominatorTree` as if it were backed by the live heap graph and trust
|
|
* that embedders with knowledge of the graph's implementation will do the
|
|
* Right Thing.
|
|
*
|
|
* Returns `mozilla::Nothing()` on OOM failure. It is the caller's
|
|
* responsibility to handle and report the OOM.
|
|
*/
|
|
static mozilla::Maybe<DominatorTree> Create(JSContext* cx,
|
|
AutoCheckCannotGC& noGC,
|
|
const Node& root) {
|
|
JS::ubi::Vector<Node> postOrder;
|
|
PredecessorSets predecessorSets;
|
|
if (!doTraversal(cx, noGC, root, postOrder, predecessorSets)) {
|
|
return mozilla::Nothing();
|
|
}
|
|
|
|
MOZ_ASSERT(postOrder.length() < UINT32_MAX);
|
|
uint32_t length = postOrder.length();
|
|
MOZ_ASSERT(postOrder[length - 1] == root);
|
|
|
|
// From here on out we wish to avoid hash table lookups, and we use
|
|
// indices into `postOrder` instead of actual nodes wherever
|
|
// possible. This greatly improves the performance of this
|
|
// implementation, but we have to pay a little bit of upfront cost to
|
|
// convert our data structures to play along first.
|
|
|
|
NodeToIndexMap nodeToPostOrderIndex(postOrder.length());
|
|
if (!mapNodesToTheirIndices(postOrder, nodeToPostOrderIndex)) {
|
|
return mozilla::Nothing();
|
|
}
|
|
|
|
JS::ubi::Vector<JS::ubi::Vector<uint32_t>> predecessorVectors;
|
|
if (!convertPredecessorSetsToVectors(root, postOrder, predecessorSets,
|
|
nodeToPostOrderIndex,
|
|
predecessorVectors))
|
|
return mozilla::Nothing();
|
|
|
|
JS::ubi::Vector<uint32_t> doms;
|
|
if (!initializeDominators(doms, length)) {
|
|
return mozilla::Nothing();
|
|
}
|
|
|
|
bool changed = true;
|
|
while (changed) {
|
|
changed = false;
|
|
|
|
// Iterate over the non-root nodes in reverse post order.
|
|
for (uint32_t indexPlusOne = length - 1; indexPlusOne > 0;
|
|
indexPlusOne--) {
|
|
MOZ_ASSERT(postOrder[indexPlusOne - 1] != root);
|
|
|
|
// Take the intersection of every predecessor's dominator set;
|
|
// that is the current best guess at the immediate dominator for
|
|
// this node.
|
|
|
|
uint32_t newIDomIdx = UNDEFINED;
|
|
|
|
auto& predecessors = predecessorVectors[indexPlusOne - 1];
|
|
auto range = predecessors.all();
|
|
for (; !range.empty(); range.popFront()) {
|
|
auto idx = range.front();
|
|
if (doms[idx] != UNDEFINED) {
|
|
newIDomIdx = idx;
|
|
break;
|
|
}
|
|
}
|
|
|
|
MOZ_ASSERT(newIDomIdx != UNDEFINED,
|
|
"Because the root is initialized to dominate itself and is "
|
|
"the first "
|
|
"node in every path, there must exist a predecessor to this "
|
|
"node that "
|
|
"also has a dominator.");
|
|
|
|
for (; !range.empty(); range.popFront()) {
|
|
auto idx = range.front();
|
|
if (doms[idx] != UNDEFINED) {
|
|
newIDomIdx = intersect(doms, newIDomIdx, idx);
|
|
}
|
|
}
|
|
|
|
// If the immediate dominator changed, we will have to do
|
|
// another pass of the outer while loop to continue the forward
|
|
// dataflow.
|
|
if (newIDomIdx != doms[indexPlusOne - 1]) {
|
|
doms[indexPlusOne - 1] = newIDomIdx;
|
|
changed = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
auto maybeDominatedSets = DominatedSets::Create(doms);
|
|
if (maybeDominatedSets.isNothing()) {
|
|
return mozilla::Nothing();
|
|
}
|
|
|
|
return mozilla::Some(
|
|
DominatorTree(std::move(postOrder), std::move(nodeToPostOrderIndex),
|
|
std::move(doms), std::move(*maybeDominatedSets)));
|
|
}
|
|
|
|
/**
|
|
* Get the root node for this dominator tree.
|
|
*/
|
|
const Node& root() const { return postOrder[postOrder.length() - 1]; }
|
|
|
|
/**
|
|
* Return the immediate dominator of the given `node`. If `node` was not
|
|
* reachable from the `root` that this dominator tree was constructed from,
|
|
* then return the null `JS::ubi::Node`.
|
|
*/
|
|
Node getImmediateDominator(const Node& node) const {
|
|
assertSanity();
|
|
auto ptr = nodeToPostOrderIndex.lookup(node);
|
|
if (!ptr) {
|
|
return Node();
|
|
}
|
|
|
|
auto idx = ptr->value();
|
|
MOZ_ASSERT(idx < postOrder.length());
|
|
return postOrder[doms[idx]];
|
|
}
|
|
|
|
/**
|
|
* Get the set of nodes immediately dominated by the given `node`. If `node`
|
|
* is not a member of this dominator tree, return `Nothing`.
|
|
*
|
|
* Example usage:
|
|
*
|
|
* mozilla::Maybe<DominatedSetRange> range =
|
|
* myDominatorTree.getDominatedSet(myNode);
|
|
* if (range.isNothing()) {
|
|
* // Handle unknown node however you see fit...
|
|
* return false;
|
|
* }
|
|
*
|
|
* for (const JS::ubi::Node& dominatedNode : *range) {
|
|
* // Do something with each immediately dominated node...
|
|
* }
|
|
*/
|
|
mozilla::Maybe<DominatedSetRange> getDominatedSet(const Node& node) {
|
|
assertSanity();
|
|
auto ptr = nodeToPostOrderIndex.lookup(node);
|
|
if (!ptr) {
|
|
return mozilla::Nothing();
|
|
}
|
|
|
|
auto idx = ptr->value();
|
|
MOZ_ASSERT(idx < postOrder.length());
|
|
return mozilla::Some(dominatedSets.dominatedSet(postOrder, idx));
|
|
}
|
|
|
|
/**
|
|
* Get the retained size of the given `node`. The size is placed in
|
|
* `outSize`, or 0 if `node` is not a member of the dominator tree. Returns
|
|
* false on OOM failure, leaving `outSize` unchanged.
|
|
*/
|
|
MOZ_MUST_USE bool getRetainedSize(const Node& node,
|
|
mozilla::MallocSizeOf mallocSizeOf,
|
|
Node::Size& outSize) {
|
|
assertSanity();
|
|
auto ptr = nodeToPostOrderIndex.lookup(node);
|
|
if (!ptr) {
|
|
outSize = 0;
|
|
return true;
|
|
}
|
|
|
|
if (retainedSizes.isNothing() && !computeRetainedSizes(mallocSizeOf)) {
|
|
return false;
|
|
}
|
|
|
|
auto idx = ptr->value();
|
|
MOZ_ASSERT(idx < postOrder.length());
|
|
outSize = retainedSizes.ref()[idx];
|
|
return true;
|
|
}
|
|
};
|
|
|
|
} // namespace ubi
|
|
} // namespace JS
|
|
|
|
#endif // js_UbiNodeDominatorTree_h
|