| /* |
| * Copyright (C) 2019 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. |
| */ |
| |
| #include "config.h" |
| #include "DFGValueRepReductionPhase.h" |
| |
| #if ENABLE(DFG_JIT) |
| |
| #include "DFGGraph.h" |
| #include "DFGInsertionSet.h" |
| #include "DFGPhase.h" |
| #include "DFGPhiChildren.h" |
| #include "JSCJSValueInlines.h" |
| |
| namespace JSC { namespace DFG { |
| |
| class ValueRepReductionPhase : public Phase { |
| static constexpr bool verbose = false; |
| |
| public: |
| ValueRepReductionPhase(Graph& graph) |
| : Phase(graph, "ValueRep reduction") |
| , m_insertionSet(graph) |
| { |
| } |
| |
| bool run() |
| { |
| ASSERT(m_graph.m_form == SSA); |
| return convertValueRepsToDouble(); |
| } |
| |
| private: |
| bool convertValueRepsToDouble() |
| { |
| HashSet<Node*> candidates; |
| for (BasicBlock* block : m_graph.blocksInNaturalOrder()) { |
| for (Node* node : *block) { |
| if (node->op() == ValueRep && node->child1().useKind() == DoubleRepUse) |
| candidates.add(node); |
| } |
| } |
| |
| if (!candidates.size()) |
| return false; |
| |
| HashMap<Node*, Vector<Node*>> usersOf; |
| auto getUsersOf = [&] (Node* candidate) { |
| auto iter = usersOf.find(candidate); |
| RELEASE_ASSERT(iter != usersOf.end()); |
| return iter->value; |
| }; |
| |
| for (BasicBlock* block : m_graph.blocksInPreOrder()) { |
| for (Node* node : *block) { |
| if (node->op() == Phi || (node->op() == ValueRep && candidates.contains(node))) |
| usersOf.add(node, Vector<Node*>()); |
| |
| Vector<Node*, 3> alreadyAdded; |
| m_graph.doToChildren(node, [&] (Edge edge) { |
| Node* candidate = edge.node(); |
| if (alreadyAdded.contains(candidate)) |
| return; |
| auto iter = usersOf.find(candidate); |
| if (iter == usersOf.end()) |
| return; |
| iter->value.append(node); |
| alreadyAdded.append(candidate); |
| }); |
| } |
| } |
| |
| PhiChildren phiChildren(m_graph); |
| |
| // - Any candidate that forwards into a Phi turns that Phi into a candidate. |
| // - Any Phi-1 that forwards into another Phi-2, where Phi-2 is a candidate, |
| // makes Phi-1 a candidate too. |
| do { |
| HashSet<Node*> eligiblePhis; |
| for (Node* candidate : candidates) { |
| if (candidate->op() == Phi) { |
| phiChildren.forAllIncomingValues(candidate, [&] (Node* incoming) { |
| if (incoming->op() == Phi) |
| eligiblePhis.add(incoming); |
| }); |
| } |
| |
| for (Node* user : getUsersOf(candidate)) { |
| if (user->op() == Upsilon) |
| eligiblePhis.add(user->phi()); |
| } |
| } |
| |
| bool sawNewCandidate = false; |
| for (Node* phi : eligiblePhis) |
| sawNewCandidate |= candidates.add(phi).isNewEntry; |
| |
| if (!sawNewCandidate) |
| break; |
| } while (true); |
| |
| do { |
| HashSet<Node*> toRemove; |
| |
| auto isEscaped = [&] (Node* node) { |
| return !candidates.contains(node) || toRemove.contains(node); |
| }; |
| |
| // Escape rules are as follows: |
| // - Any non-well-known use is an escape. Currently, we allow DoubleRep, Hints, Upsilons (described below). |
| // - Any Upsilon that forwards the candidate into an escaped phi escapes the candidate. |
| // - A Phi remains a candidate as long as all values flowing into it can be made a double. |
| // Currently, this means these are valid things we support to forward into the Phi: |
| // - A JSConstant(some number "x") => DoubleConstant("x") |
| // - ValueRep(DoubleRepUse:@x) => @x |
| // - A Phi so long as that Phi is not escaped. |
| for (Node* candidate : candidates) { |
| bool ok = true; |
| |
| auto dumpEscape = [&] (const char* description, Node* node) { |
| if (!verbose) |
| return; |
| dataLogLn(description); |
| dataLog(" candidate: "); |
| m_graph.dump(WTF::dataFile(), Prefix::noString, candidate); |
| dataLog(" reason: "); |
| m_graph.dump(WTF::dataFile(), Prefix::noString, node); |
| dataLogLn(); |
| }; |
| |
| if (candidate->op() == Phi) { |
| phiChildren.forAllIncomingValues(candidate, [&] (Node* node) { |
| if (node->op() == JSConstant) { |
| if (!node->asJSValue().isNumber()) { |
| ok = false; |
| dumpEscape("Phi Incoming JSConstant not a number: ", node); |
| } |
| } else if (node->op() == ValueRep) { |
| if (node->child1().useKind() != DoubleRepUse) { |
| ok = false; |
| dumpEscape("Phi Incoming ValueRep not DoubleRepUse: ", node); |
| } |
| } else if (node->op() == Phi) { |
| if (isEscaped(node)) { |
| ok = false; |
| dumpEscape("An incoming Phi to another Phi is escaped: ", node); |
| } |
| } else { |
| ok = false; |
| dumpEscape("Unsupported incoming value to Phi: ", node); |
| } |
| }); |
| |
| if (!ok) { |
| toRemove.add(candidate); |
| continue; |
| } |
| } |
| |
| for (Node* user : getUsersOf(candidate)) { |
| switch (user->op()) { |
| case DoubleRep: |
| if (user->child1().useKind() != RealNumberUse) { |
| ok = false; |
| dumpEscape("DoubleRep escape: ", user); |
| } |
| break; |
| |
| case PutHint: |
| case MovHint: |
| break; |
| |
| case Upsilon: { |
| Node* phi = user->phi(); |
| if (isEscaped(phi)) { |
| dumpEscape("Upsilon of escaped phi escapes candidate: ", phi); |
| ok = false; |
| } |
| break; |
| } |
| |
| default: |
| dumpEscape("Normal escape: ", user); |
| ok = false; |
| break; |
| } |
| |
| if (!ok) |
| break; |
| } |
| |
| if (!ok) |
| toRemove.add(candidate); |
| } |
| |
| if (toRemove.isEmpty()) |
| break; |
| |
| for (Node* node : toRemove) |
| candidates.remove(node); |
| } while (true); |
| |
| if (!candidates.size()) |
| return false; |
| |
| NodeOrigin originForConstant = m_graph.block(0)->at(0)->origin; |
| HashSet<Node*> doubleRepRealCheckLocations; |
| |
| for (Node* candidate : candidates) { |
| if (verbose) |
| dataLogLn("Optimized: ", candidate); |
| |
| Node* resultNode; |
| if (candidate->op() == Phi) { |
| resultNode = candidate; |
| |
| for (Node* upsilon : phiChildren.upsilonsOf(candidate)) { |
| Node* incomingValue = upsilon->child1().node(); |
| Node* newChild; |
| if (incomingValue->op() == JSConstant) { |
| double number = incomingValue->asJSValue().asNumber(); |
| newChild = m_insertionSet.insertConstant(0, originForConstant, jsDoubleNumber(number), DoubleConstant); |
| } else if (incomingValue->op() == ValueRep) { |
| // We don't care about the incoming value being an impure NaN because users of |
| // this Phi are either OSR exit or DoubleRep(RealNumberUse:@phi) |
| ASSERT(incomingValue->child1().useKind() == DoubleRepUse); |
| newChild = incomingValue->child1().node(); |
| } else if (incomingValue->op() == Phi) |
| newChild = incomingValue; |
| else |
| RELEASE_ASSERT_NOT_REACHED(); |
| |
| upsilon->child1() = Edge(newChild, DoubleRepUse); |
| } |
| |
| candidate->setResult(NodeResultDouble); |
| } else if (candidate->op() == ValueRep) |
| resultNode = candidate->child1().node(); |
| else |
| RELEASE_ASSERT_NOT_REACHED(); |
| |
| for (Node* user : getUsersOf(candidate)) { |
| switch (user->op()) { |
| case DoubleRep: { |
| ASSERT(user->child1().useKind() == RealNumberUse); |
| user->convertToIdentityOn(resultNode); |
| doubleRepRealCheckLocations.add(user); |
| break; |
| } |
| |
| case PutHint: |
| user->child2() = Edge(resultNode, DoubleRepUse); |
| break; |
| |
| case MovHint: |
| user->child1() = Edge(resultNode, DoubleRepUse); |
| break; |
| |
| case Upsilon: { |
| Node* phi = user->phi(); |
| ASSERT_UNUSED(phi, candidates.contains(phi)); |
| break; |
| } |
| |
| default: |
| RELEASE_ASSERT_NOT_REACHED(); |
| break; |
| } |
| } |
| } |
| |
| // Insert constants. |
| m_insertionSet.execute(m_graph.block(0)); |
| |
| // Insert checks that are needed when removing DoubleRep(RealNumber:@x) |
| if (doubleRepRealCheckLocations.size()) { |
| for (BasicBlock* block : m_graph.blocksInNaturalOrder()) { |
| for (unsigned i = 0; i < block->size(); ++i) { |
| Node* node = block->at(i); |
| if (node->op() != Identity) { |
| ASSERT(!doubleRepRealCheckLocations.contains(node)); |
| continue; |
| } |
| if (!doubleRepRealCheckLocations.contains(node)) |
| continue; |
| m_insertionSet.insertNode( |
| i, SpecNone, Check, node->origin, |
| Edge(node->child1().node(), DoubleRepRealUse)); |
| } |
| |
| m_insertionSet.execute(block); |
| } |
| } |
| |
| return true; |
| } |
| |
| InsertionSet m_insertionSet; |
| }; |
| |
| bool performValueRepReduction(Graph& graph) |
| { |
| return runPhase<ValueRepReductionPhase>(graph); |
| } |
| |
| } } // namespace JSC::DFG |
| |
| #endif // ENABLE(DFG_JIT) |
| |
