| /* |
| * Copyright (C) 2011-2017 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #pragma once |
| |
| #include <wtf/CommaPrinter.h> |
| #include <wtf/FastBitVector.h> |
| #include <wtf/GraphNodeWorklist.h> |
| #include <wtf/Vector.h> |
| |
| namespace WTF { |
| |
| // This is a utility for finding the dominators of a graph. Dominators are almost universally used |
| // for control flow graph analysis, so this code will refer to the graph's "nodes" as "blocks". In |
| // that regard this code is kind of specialized for the various JSC compilers, but you could use it |
| // for non-compiler things if you are OK with referring to your "nodes" as "blocks". |
| |
| template<typename Graph> |
| class Dominators { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| using List = typename Graph::List; |
| |
| Dominators(Graph& graph, bool selfCheck = false) |
| : m_graph(graph) |
| , m_data(graph.template newMap<BlockData>()) |
| { |
| LengauerTarjan lengauerTarjan(m_graph); |
| lengauerTarjan.compute(); |
| |
| // From here we want to build a spanning tree with both upward and downward links and we want |
| // to do a search over this tree to compute pre and post numbers that can be used for dominance |
| // tests. |
| |
| for (unsigned blockIndex = m_graph.numNodes(); blockIndex--;) { |
| typename Graph::Node block = m_graph.node(blockIndex); |
| if (!block) |
| continue; |
| |
| typename Graph::Node idomBlock = lengauerTarjan.immediateDominator(block); |
| m_data[block].idomParent = idomBlock; |
| if (idomBlock) |
| m_data[idomBlock].idomKids.append(block); |
| } |
| |
| unsigned nextPreNumber = 0; |
| unsigned nextPostNumber = 0; |
| |
| // Plain stack-based worklist because we are guaranteed to see each block exactly once anyway. |
| Vector<GraphNodeWithOrder<typename Graph::Node>> worklist; |
| worklist.append(GraphNodeWithOrder<typename Graph::Node>(m_graph.root(), GraphVisitOrder::Pre)); |
| while (!worklist.isEmpty()) { |
| GraphNodeWithOrder<typename Graph::Node> item = worklist.takeLast(); |
| switch (item.order) { |
| case GraphVisitOrder::Pre: |
| m_data[item.node].preNumber = nextPreNumber++; |
| worklist.append(GraphNodeWithOrder<typename Graph::Node>(item.node, GraphVisitOrder::Post)); |
| for (typename Graph::Node kid : m_data[item.node].idomKids) |
| worklist.append(GraphNodeWithOrder<typename Graph::Node>(kid, GraphVisitOrder::Pre)); |
| break; |
| case GraphVisitOrder::Post: |
| m_data[item.node].postNumber = nextPostNumber++; |
| break; |
| } |
| } |
| |
| if (selfCheck) { |
| // Check our dominator calculation: |
| // 1) Check that our range-based ancestry test is the same as a naive ancestry test. |
| // 2) Check that our notion of who dominates whom is identical to a naive (not |
| // Lengauer-Tarjan) dominator calculation. |
| |
| ValidationContext context(m_graph, *this); |
| |
| for (unsigned fromBlockIndex = m_graph.numNodes(); fromBlockIndex--;) { |
| typename Graph::Node fromBlock = m_graph.node(fromBlockIndex); |
| if (!fromBlock || m_data[fromBlock].preNumber == UINT_MAX) |
| continue; |
| for (unsigned toBlockIndex = m_graph.numNodes(); toBlockIndex--;) { |
| typename Graph::Node toBlock = m_graph.node(toBlockIndex); |
| if (!toBlock || m_data[toBlock].preNumber == UINT_MAX) |
| continue; |
| |
| if (dominates(fromBlock, toBlock) != naiveDominates(fromBlock, toBlock)) |
| context.reportError(fromBlock, toBlock, "Range-based domination check is broken"); |
| if (dominates(fromBlock, toBlock) != context.naiveDominators.dominates(fromBlock, toBlock)) |
| context.reportError(fromBlock, toBlock, "Lengauer-Tarjan domination is broken"); |
| } |
| } |
| |
| context.handleErrors(); |
| } |
| } |
| |
| bool strictlyDominates(typename Graph::Node from, typename Graph::Node to) const |
| { |
| return m_data[to].preNumber > m_data[from].preNumber |
| && m_data[to].postNumber < m_data[from].postNumber; |
| } |
| |
| bool dominates(typename Graph::Node from, typename Graph::Node to) const |
| { |
| return from == to || strictlyDominates(from, to); |
| } |
| |
| // Returns the immediate dominator of this block. Returns null for the root block. |
| typename Graph::Node idom(typename Graph::Node block) const |
| { |
| return m_data[block].idomParent; |
| } |
| |
| template<typename Functor> |
| void forAllStrictDominatorsOf(typename Graph::Node to, const Functor& functor) const |
| { |
| for (typename Graph::Node block = m_data[to].idomParent; block; block = m_data[block].idomParent) |
| functor(block); |
| } |
| |
| // Note: This will visit the dominators starting with the 'to' node and moving up the idom tree |
| // until it gets to the root. Some clients of this function, like B3::moveConstants(), rely on this |
| // order. |
| template<typename Functor> |
| void forAllDominatorsOf(typename Graph::Node to, const Functor& functor) const |
| { |
| for (typename Graph::Node block = to; block; block = m_data[block].idomParent) |
| functor(block); |
| } |
| |
| template<typename Functor> |
| void forAllBlocksStrictlyDominatedBy(typename Graph::Node from, const Functor& functor) const |
| { |
| Vector<typename Graph::Node, 16> worklist; |
| worklist.appendVector(m_data[from].idomKids); |
| while (!worklist.isEmpty()) { |
| typename Graph::Node block = worklist.takeLast(); |
| functor(block); |
| worklist.appendVector(m_data[block].idomKids); |
| } |
| } |
| |
| template<typename Functor> |
| void forAllBlocksDominatedBy(typename Graph::Node from, const Functor& functor) const |
| { |
| Vector<typename Graph::Node, 16> worklist; |
| worklist.append(from); |
| while (!worklist.isEmpty()) { |
| typename Graph::Node block = worklist.takeLast(); |
| functor(block); |
| worklist.appendVector(m_data[block].idomKids); |
| } |
| } |
| |
| typename Graph::Set strictDominatorsOf(typename Graph::Node to) const |
| { |
| typename Graph::Set result; |
| forAllStrictDominatorsOf( |
| to, |
| [&] (typename Graph::Node node) { |
| result.add(node); |
| }); |
| return result; |
| } |
| |
| typename Graph::Set dominatorsOf(typename Graph::Node to) const |
| { |
| typename Graph::Set result; |
| forAllDominatorsOf( |
| to, |
| [&] (typename Graph::Node node) { |
| result.add(node); |
| }); |
| return result; |
| } |
| |
| typename Graph::Set blocksStrictlyDominatedBy(typename Graph::Node from) const |
| { |
| typename Graph::Set result; |
| forAllBlocksStrictlyDominatedBy( |
| from, |
| [&] (typename Graph::Node node) { |
| result.add(node); |
| }); |
| return result; |
| } |
| |
| typename Graph::Set blocksDominatedBy(typename Graph::Node from) const |
| { |
| typename Graph::Set result; |
| forAllBlocksDominatedBy( |
| from, |
| [&] (typename Graph::Node node) { |
| result.add(node); |
| }); |
| return result; |
| } |
| |
| template<typename Functor> |
| void forAllBlocksInDominanceFrontierOf( |
| typename Graph::Node from, const Functor& functor) const |
| { |
| typename Graph::Set set; |
| forAllBlocksInDominanceFrontierOfImpl( |
| from, |
| [&] (typename Graph::Node block) { |
| if (set.add(block)) |
| functor(block); |
| }); |
| } |
| |
| typename Graph::Set dominanceFrontierOf(typename Graph::Node from) const |
| { |
| typename Graph::Set result; |
| forAllBlocksInDominanceFrontierOf( |
| from, |
| [&] (typename Graph::Node node) { |
| result.add(node); |
| }); |
| return result; |
| } |
| |
| template<typename Functor> |
| void forAllBlocksInIteratedDominanceFrontierOf(const List& from, const Functor& functor) |
| { |
| forAllBlocksInPrunedIteratedDominanceFrontierOf( |
| from, |
| [&] (typename Graph::Node block) -> bool { |
| functor(block); |
| return true; |
| }); |
| } |
| |
| // This is a close relative of forAllBlocksInIteratedDominanceFrontierOf(), which allows the |
| // given functor to return false to indicate that we don't wish to consider the given block. |
| // Useful for computing pruned SSA form. |
| template<typename Functor> |
| void forAllBlocksInPrunedIteratedDominanceFrontierOf( |
| const List& from, const Functor& functor) |
| { |
| typename Graph::Set set; |
| forAllBlocksInIteratedDominanceFrontierOfImpl( |
| from, |
| [&] (typename Graph::Node block) -> bool { |
| if (!set.add(block)) |
| return false; |
| return functor(block); |
| }); |
| } |
| |
| typename Graph::Set iteratedDominanceFrontierOf(const List& from) const |
| { |
| typename Graph::Set result; |
| forAllBlocksInIteratedDominanceFrontierOfImpl( |
| from, |
| [&] (typename Graph::Node node) -> bool { |
| return result.add(node); |
| }); |
| return result; |
| } |
| |
| void dump(PrintStream& out) const |
| { |
| for (unsigned blockIndex = 0; blockIndex < m_data.size(); ++blockIndex) { |
| if (m_data[blockIndex].preNumber == UINT_MAX) |
| continue; |
| |
| out.print(" Block #", blockIndex, ": idom = ", m_graph.dump(m_data[blockIndex].idomParent), ", idomKids = ["); |
| CommaPrinter comma; |
| for (unsigned i = 0; i < m_data[blockIndex].idomKids.size(); ++i) |
| out.print(comma, m_graph.dump(m_data[blockIndex].idomKids[i])); |
| out.print("], pre/post = ", m_data[blockIndex].preNumber, "/", m_data[blockIndex].postNumber, "\n"); |
| } |
| } |
| |
| private: |
| // This implements Lengauer and Tarjan's "A Fast Algorithm for Finding Dominators in a Flowgraph" |
| // (TOPLAS 1979). It uses the "simple" implementation of LINK and EVAL, which yields an O(n log n) |
| // solution. The full paper is linked below; this code attempts to closely follow the algorithm as |
| // it is presented in the paper; in particular sections 3 and 4 as well as appendix B. |
| // https://www.cs.princeton.edu/courses/archive/fall03/cs528/handouts/a%20fast%20algorithm%20for%20finding.pdf |
| // |
| // This code is very subtle. The Lengauer-Tarjan algorithm is incredibly deep to begin with. The |
| // goal of this code is to follow the code in the paper, however our implementation must deviate |
| // from the paper when it comes to recursion. The authors had used recursion to implement DFS, and |
| // also to implement the "simple" EVAL. We convert both of those into worklist-based solutions. |
| // Finally, once the algorithm gives us immediate dominators, we implement dominance tests by |
| // walking the dominator tree and computing pre and post numbers. We then use the range inclusion |
| // check trick that was first discovered by Paul F. Dietz in 1982 in "Maintaining order in a linked |
| // list" (see http://dl.acm.org/citation.cfm?id=802184). |
| |
| class LengauerTarjan { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| LengauerTarjan(Graph& graph) |
| : m_graph(graph) |
| , m_data(graph.template newMap<BlockData>()) |
| { |
| for (unsigned blockIndex = m_graph.numNodes(); blockIndex--;) { |
| typename Graph::Node block = m_graph.node(blockIndex); |
| if (!block) |
| continue; |
| m_data[block].label = block; |
| } |
| } |
| |
| void compute() |
| { |
| computeDepthFirstPreNumbering(); // Step 1. |
| computeSemiDominatorsAndImplicitImmediateDominators(); // Steps 2 and 3. |
| computeExplicitImmediateDominators(); // Step 4. |
| } |
| |
| typename Graph::Node immediateDominator(typename Graph::Node block) |
| { |
| return m_data[block].dom; |
| } |
| |
| private: |
| void computeDepthFirstPreNumbering() |
| { |
| // Use a block worklist that also tracks the index inside the successor list. This is |
| // necessary for ensuring that we don't attempt to visit a successor until the previous |
| // successors that we had visited are fully processed. This ends up being revealed in the |
| // output of this method because the first time we see an edge to a block, we set the |
| // block's parent. So, if we have: |
| // |
| // A -> B |
| // A -> C |
| // B -> C |
| // |
| // And we're processing A, then we want to ensure that if we see A->B first (and hence set |
| // B's prenumber before we set C's) then we also end up setting C's parent to B by virtue |
| // of not noticing A->C until we're done processing B. |
| |
| ExtendedGraphNodeWorklist<typename Graph::Node, unsigned, typename Graph::Set> worklist; |
| worklist.push(m_graph.root(), 0); |
| |
| while (GraphNodeWith<typename Graph::Node, unsigned> item = worklist.pop()) { |
| typename Graph::Node block = item.node; |
| unsigned successorIndex = item.data; |
| |
| // We initially push with successorIndex = 0 regardless of whether or not we have any |
| // successors. This is so that we can assign our prenumber. Subsequently we get pushed |
| // with higher successorIndex values, but only if they are in range. |
| ASSERT(!successorIndex || successorIndex < m_graph.successors(block).size()); |
| |
| if (!successorIndex) { |
| m_data[block].semiNumber = m_blockByPreNumber.size(); |
| m_blockByPreNumber.append(block); |
| } |
| |
| if (successorIndex < m_graph.successors(block).size()) { |
| unsigned nextSuccessorIndex = successorIndex + 1; |
| if (nextSuccessorIndex < m_graph.successors(block).size()) |
| worklist.forcePush(block, nextSuccessorIndex); |
| |
| typename Graph::Node successorBlock = m_graph.successors(block)[successorIndex]; |
| if (worklist.push(successorBlock, 0)) |
| m_data[successorBlock].parent = block; |
| } |
| } |
| } |
| |
| void computeSemiDominatorsAndImplicitImmediateDominators() |
| { |
| for (unsigned currentPreNumber = m_blockByPreNumber.size(); currentPreNumber-- > 1;) { |
| typename Graph::Node block = m_blockByPreNumber[currentPreNumber]; |
| BlockData& blockData = m_data[block]; |
| |
| // Step 2: |
| for (typename Graph::Node predecessorBlock : m_graph.predecessors(block)) { |
| typename Graph::Node intermediateBlock = eval(predecessorBlock); |
| blockData.semiNumber = std::min( |
| m_data[intermediateBlock].semiNumber, blockData.semiNumber); |
| } |
| unsigned bucketPreNumber = blockData.semiNumber; |
| ASSERT(bucketPreNumber <= currentPreNumber); |
| m_data[m_blockByPreNumber[bucketPreNumber]].bucket.append(block); |
| link(blockData.parent, block); |
| |
| // Step 3: |
| for (typename Graph::Node semiDominee : m_data[blockData.parent].bucket) { |
| typename Graph::Node possibleDominator = eval(semiDominee); |
| BlockData& semiDomineeData = m_data[semiDominee]; |
| ASSERT(m_blockByPreNumber[semiDomineeData.semiNumber] == blockData.parent); |
| BlockData& possibleDominatorData = m_data[possibleDominator]; |
| if (possibleDominatorData.semiNumber < semiDomineeData.semiNumber) |
| semiDomineeData.dom = possibleDominator; |
| else |
| semiDomineeData.dom = blockData.parent; |
| } |
| m_data[blockData.parent].bucket.clear(); |
| } |
| } |
| |
| void computeExplicitImmediateDominators() |
| { |
| for (unsigned currentPreNumber = 1; currentPreNumber < m_blockByPreNumber.size(); ++currentPreNumber) { |
| typename Graph::Node block = m_blockByPreNumber[currentPreNumber]; |
| BlockData& blockData = m_data[block]; |
| |
| if (blockData.dom != m_blockByPreNumber[blockData.semiNumber]) |
| blockData.dom = m_data[blockData.dom].dom; |
| } |
| } |
| |
| void link(typename Graph::Node from, typename Graph::Node to) |
| { |
| m_data[to].ancestor = from; |
| } |
| |
| typename Graph::Node eval(typename Graph::Node block) |
| { |
| if (!m_data[block].ancestor) |
| return block; |
| |
| compress(block); |
| return m_data[block].label; |
| } |
| |
| void compress(typename Graph::Node initialBlock) |
| { |
| // This was meant to be a recursive function, but we don't like recursion because we don't |
| // want to blow the stack. The original function will call compress() recursively on the |
| // ancestor of anything that has an ancestor. So, we populate our worklist with the |
| // recursive ancestors of initialBlock. Then we process the list starting from the block |
| // that is furthest up the ancestor chain. |
| |
| typename Graph::Node ancestor = m_data[initialBlock].ancestor; |
| ASSERT(ancestor); |
| if (!m_data[ancestor].ancestor) |
| return; |
| |
| Vector<typename Graph::Node, 16> stack; |
| for (typename Graph::Node block = initialBlock; block; block = m_data[block].ancestor) |
| stack.append(block); |
| |
| // We only care about blocks that have an ancestor that has an ancestor. The last two |
| // elements in the stack won't satisfy this property. |
| ASSERT(stack.size() >= 2); |
| ASSERT(!m_data[stack[stack.size() - 1]].ancestor); |
| ASSERT(!m_data[m_data[stack[stack.size() - 2]].ancestor].ancestor); |
| |
| for (unsigned i = stack.size() - 2; i--;) { |
| typename Graph::Node block = stack[i]; |
| typename Graph::Node& labelOfBlock = m_data[block].label; |
| typename Graph::Node& ancestorOfBlock = m_data[block].ancestor; |
| ASSERT(ancestorOfBlock); |
| ASSERT(m_data[ancestorOfBlock].ancestor); |
| |
| typename Graph::Node labelOfAncestorOfBlock = m_data[ancestorOfBlock].label; |
| |
| if (m_data[labelOfAncestorOfBlock].semiNumber < m_data[labelOfBlock].semiNumber) |
| labelOfBlock = labelOfAncestorOfBlock; |
| ancestorOfBlock = m_data[ancestorOfBlock].ancestor; |
| } |
| } |
| |
| struct BlockData { |
| WTF_MAKE_STRUCT_FAST_ALLOCATED; |
| |
| BlockData() |
| : parent(nullptr) |
| , preNumber(UINT_MAX) |
| , semiNumber(UINT_MAX) |
| , ancestor(nullptr) |
| , label(nullptr) |
| , dom(nullptr) |
| { |
| } |
| |
| typename Graph::Node parent; |
| unsigned preNumber; |
| unsigned semiNumber; |
| typename Graph::Node ancestor; |
| typename Graph::Node label; |
| Vector<typename Graph::Node> bucket; |
| typename Graph::Node dom; |
| }; |
| |
| Graph& m_graph; |
| typename Graph::template Map<BlockData> m_data; |
| Vector<typename Graph::Node> m_blockByPreNumber; |
| }; |
| |
| class NaiveDominators { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| NaiveDominators(Graph& graph) |
| : m_graph(graph) |
| { |
| // This implements a naive dominator solver. |
| |
| ASSERT(!graph.predecessors(graph.root()).size()); |
| |
| unsigned numBlocks = graph.numNodes(); |
| |
| // Allocate storage for the dense dominance matrix. |
| m_results.grow(numBlocks); |
| for (unsigned i = numBlocks; i--;) |
| m_results[i].resize(numBlocks); |
| m_scratch.resize(numBlocks); |
| |
| // We know that the entry block is only dominated by itself. |
| m_results[0].clearAll(); |
| m_results[0][0] = true; |
| |
| // Find all of the valid blocks. |
| m_scratch.clearAll(); |
| for (unsigned i = numBlocks; i--;) { |
| if (!graph.node(i)) |
| continue; |
| m_scratch[i] = true; |
| } |
| |
| // Mark all nodes as dominated by everything. |
| for (unsigned i = numBlocks; i-- > 1;) { |
| if (!graph.node(i) || !graph.predecessors(graph.node(i)).size()) |
| m_results[i].clearAll(); |
| else |
| m_results[i] = m_scratch; |
| } |
| |
| // Iteratively eliminate nodes that are not dominator. |
| bool changed; |
| do { |
| changed = false; |
| // Prune dominators in all non entry blocks: forward scan. |
| for (unsigned i = 1; i < numBlocks; ++i) |
| changed |= pruneDominators(i); |
| |
| if (!changed) |
| break; |
| |
| // Prune dominators in all non entry blocks: backward scan. |
| changed = false; |
| for (unsigned i = numBlocks; i-- > 1;) |
| changed |= pruneDominators(i); |
| } while (changed); |
| } |
| |
| bool dominates(unsigned from, unsigned to) const |
| { |
| return m_results[to][from]; |
| } |
| |
| bool dominates(typename Graph::Node from, typename Graph::Node to) const |
| { |
| return dominates(m_graph.index(from), m_graph.index(to)); |
| } |
| |
| void dump(PrintStream& out) const |
| { |
| for (unsigned blockIndex = 0; blockIndex < m_graph.numNodes(); ++blockIndex) { |
| typename Graph::Node block = m_graph.node(blockIndex); |
| if (!block) |
| continue; |
| out.print(" Block ", m_graph.dump(block), ":"); |
| for (unsigned otherIndex = 0; otherIndex < m_graph.numNodes(); ++otherIndex) { |
| if (!dominates(m_graph.index(block), otherIndex)) |
| continue; |
| out.print(" ", m_graph.dump(m_graph.node(otherIndex))); |
| } |
| out.print("\n"); |
| } |
| } |
| |
| private: |
| bool pruneDominators(unsigned idx) |
| { |
| typename Graph::Node block = m_graph.node(idx); |
| |
| if (!block || !m_graph.predecessors(block).size()) |
| return false; |
| |
| // Find the intersection of dom(preds). |
| m_scratch = m_results[m_graph.index(m_graph.predecessors(block)[0])]; |
| for (unsigned j = m_graph.predecessors(block).size(); j-- > 1;) |
| m_scratch &= m_results[m_graph.index(m_graph.predecessors(block)[j])]; |
| |
| // The block is also dominated by itself. |
| m_scratch[idx] = true; |
| |
| return m_results[idx].setAndCheck(m_scratch); |
| } |
| |
| Graph& m_graph; |
| Vector<FastBitVector> m_results; // For each block, the bitvector of blocks that dominate it. |
| FastBitVector m_scratch; // A temporary bitvector with bit for each block. We recycle this to save new/deletes. |
| }; |
| |
| struct ValidationContext { |
| WTF_MAKE_STRUCT_FAST_ALLOCATED; |
| |
| ValidationContext(Graph& graph, Dominators& dominators) |
| : graph(graph) |
| , dominators(dominators) |
| , naiveDominators(graph) |
| { |
| } |
| |
| void reportError(typename Graph::Node from, typename Graph::Node to, const char* message) |
| { |
| Error error; |
| error.from = from; |
| error.to = to; |
| error.message = message; |
| errors.append(error); |
| } |
| |
| void handleErrors() |
| { |
| if (errors.isEmpty()) |
| return; |
| |
| dataLog("DFG DOMINATOR VALIDATION FAILED:\n"); |
| dataLog("\n"); |
| dataLog("For block domination relationships:\n"); |
| for (unsigned i = 0; i < errors.size(); ++i) { |
| dataLog( |
| " ", graph.dump(errors[i].from), " -> ", graph.dump(errors[i].to), |
| " (", errors[i].message, ")\n"); |
| } |
| dataLog("\n"); |
| dataLog("Control flow graph:\n"); |
| for (unsigned blockIndex = 0; blockIndex < graph.numNodes(); ++blockIndex) { |
| typename Graph::Node block = graph.node(blockIndex); |
| if (!block) |
| continue; |
| dataLog(" Block ", graph.dump(graph.node(blockIndex)), ": successors = ["); |
| CommaPrinter comma; |
| for (auto successor : graph.successors(block)) |
| dataLog(comma, graph.dump(successor)); |
| dataLog("], predecessors = ["); |
| comma = CommaPrinter(); |
| for (auto predecessor : graph.predecessors(block)) |
| dataLog(comma, graph.dump(predecessor)); |
| dataLog("]\n"); |
| } |
| dataLog("\n"); |
| dataLog("Lengauer-Tarjan Dominators:\n"); |
| dataLog(dominators); |
| dataLog("\n"); |
| dataLog("Naive Dominators:\n"); |
| naiveDominators.dump(WTF::dataFile()); |
| dataLog("\n"); |
| dataLog("Graph at time of failure:\n"); |
| dataLog(graph); |
| dataLog("\n"); |
| dataLog("DFG DOMINATOR VALIDATION FAILIED!\n"); |
| CRASH(); |
| } |
| |
| Graph& graph; |
| Dominators& dominators; |
| NaiveDominators naiveDominators; |
| |
| struct Error { |
| WTF_MAKE_STRUCT_FAST_ALLOCATED; |
| |
| typename Graph::Node from; |
| typename Graph::Node to; |
| const char* message; |
| }; |
| |
| Vector<Error> errors; |
| }; |
| |
| bool naiveDominates(typename Graph::Node from, typename Graph::Node to) const |
| { |
| for (typename Graph::Node block = to; block; block = m_data[block].idomParent) { |
| if (block == from) |
| return true; |
| } |
| return false; |
| } |
| |
| template<typename Functor> |
| void forAllBlocksInDominanceFrontierOfImpl( |
| typename Graph::Node from, const Functor& functor) const |
| { |
| // Paraphrasing from http://en.wikipedia.org/wiki/Dominator_(graph_theory): |
| // "The dominance frontier of a block 'from' is the set of all blocks 'to' such that |
| // 'from' dominates an immediate predecessor of 'to', but 'from' does not strictly |
| // dominate 'to'." |
| // |
| // A useful corner case to remember: a block may be in its own dominance frontier if it has |
| // a loop edge to itself, since it dominates itself and so it dominates its own immediate |
| // predecessor, and a block never strictly dominates itself. |
| |
| forAllBlocksDominatedBy( |
| from, |
| [&] (typename Graph::Node block) { |
| for (typename Graph::Node to : m_graph.successors(block)) { |
| if (!strictlyDominates(from, to)) |
| functor(to); |
| } |
| }); |
| } |
| |
| template<typename Functor> |
| void forAllBlocksInIteratedDominanceFrontierOfImpl( |
| const List& from, const Functor& functor) const |
| { |
| List worklist = from; |
| while (!worklist.isEmpty()) { |
| typename Graph::Node block = worklist.takeLast(); |
| forAllBlocksInDominanceFrontierOfImpl( |
| block, |
| [&] (typename Graph::Node otherBlock) { |
| if (functor(otherBlock)) |
| worklist.append(otherBlock); |
| }); |
| } |
| } |
| |
| struct BlockData { |
| WTF_MAKE_STRUCT_FAST_ALLOCATED; |
| |
| BlockData() |
| : idomParent(nullptr) |
| , preNumber(UINT_MAX) |
| , postNumber(UINT_MAX) |
| { |
| } |
| |
| Vector<typename Graph::Node> idomKids; |
| typename Graph::Node idomParent; |
| |
| unsigned preNumber; |
| unsigned postNumber; |
| }; |
| |
| Graph& m_graph; |
| typename Graph::template Map<BlockData> m_data; |
| }; |
| |
| } // namespace WTF |
| |
| using WTF::Dominators; |
