LCOV - code coverage report
Current view: top level - src/compiler - control-equivalence.cc (source / functions) Hit Total Coverage
Test: app.info Lines: 95 101 94.1 %
Date: 2019-04-17 Functions: 12 13 92.3 %

          Line data    Source code
       1             : // Copyright 2015 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #include "src/compiler/control-equivalence.h"
       6             : #include "src/compiler/node-properties.h"
       7             : 
       8             : #define TRACE(...)                                 \
       9             :   do {                                             \
      10             :     if (FLAG_trace_turbo_ceq) PrintF(__VA_ARGS__); \
      11             :   } while (false)
      12             : 
      13             : namespace v8 {
      14             : namespace internal {
      15             : namespace compiler {
      16             : 
      17       38966 : void ControlEquivalence::Run(Node* exit) {
      18       38969 :   if (!Participates(exit) || GetClass(exit) == kInvalidClass) {
      19       38964 :     DetermineParticipation(exit);
      20       38965 :     RunUndirectedDFS(exit);
      21             :   }
      22       38969 : }
      23             : 
      24             : 
      25             : // static
      26             : STATIC_CONST_MEMBER_DEFINITION const size_t ControlEquivalence::kInvalidClass;
      27             : 
      28             : 
      29           0 : void ControlEquivalence::VisitPre(Node* node) {
      30      185753 :   TRACE("CEQ: Pre-visit of #%d:%s\n", node->id(), node->op()->mnemonic());
      31           0 : }
      32             : 
      33             : 
      34      185753 : void ControlEquivalence::VisitMid(Node* node, DFSDirection direction) {
      35      185753 :   TRACE("CEQ: Mid-visit of #%d:%s\n", node->id(), node->op()->mnemonic());
      36             :   BracketList& blist = GetBracketList(node);
      37             : 
      38             :   // Remove brackets pointing to this node [line:19].
      39      185755 :   BracketListDelete(blist, node, direction);
      40             : 
      41             :   // Potentially introduce artificial dependency from start to end.
      42      185753 :   if (blist.empty()) {
      43             :     DCHECK_EQ(kInputDirection, direction);
      44       38965 :     VisitBackedge(node, graph_->end(), kInputDirection);
      45             :   }
      46             : 
      47             :   // Potentially start a new equivalence class [line:37].
      48      185753 :   BracketListTRACE(blist);
      49             :   Bracket* recent = &blist.back();
      50      185751 :   if (recent->recent_size != blist.size()) {
      51      117898 :     recent->recent_size = blist.size();
      52      117898 :     recent->recent_class = NewClassNumber();
      53             :   }
      54             : 
      55             :   // Assign equivalence class to node.
      56      185751 :   SetClass(node, recent->recent_class);
      57      185752 :   TRACE("  Assigned class number is %zu\n", GetClass(node));
      58      185752 : }
      59             : 
      60             : 
      61      185750 : void ControlEquivalence::VisitPost(Node* node, Node* parent_node,
      62             :                                    DFSDirection direction) {
      63      185750 :   TRACE("CEQ: Post-visit of #%d:%s\n", node->id(), node->op()->mnemonic());
      64             :   BracketList& blist = GetBracketList(node);
      65             : 
      66             :   // Remove brackets pointing to this node [line:19].
      67      185751 :   BracketListDelete(blist, node, direction);
      68             : 
      69             :   // Propagate bracket list up the DFS tree [line:13].
      70      185749 :   if (parent_node != nullptr) {
      71             :     BracketList& parent_blist = GetBracketList(parent_node);
      72      293572 :     parent_blist.splice(parent_blist.end(), blist);
      73             :   }
      74      185750 : }
      75             : 
      76             : 
      77       78432 : void ControlEquivalence::VisitBackedge(Node* from, Node* to,
      78             :                                        DFSDirection direction) {
      79       78432 :   TRACE("CEQ: Backedge from #%d:%s to #%d:%s\n", from->id(),
      80             :         from->op()->mnemonic(), to->id(), to->op()->mnemonic());
      81             : 
      82             :   // Push backedge onto the bracket list [line:25].
      83       78432 :   Bracket bracket = {direction, kInvalidClass, 0, from, to};
      84       78432 :   GetBracketList(from).push_back(bracket);
      85       78432 : }
      86             : 
      87             : 
      88       38964 : void ControlEquivalence::RunUndirectedDFS(Node* exit) {
      89       38964 :   ZoneStack<DFSStackEntry> stack(zone_);
      90       38965 :   DFSPush(stack, exit, nullptr, kInputDirection);
      91             :   VisitPre(exit);
      92             : 
      93     1293405 :   while (!stack.empty()) {  // Undirected depth-first backwards traversal.
      94             :     DFSStackEntry& entry = stack.top();
      95     1254440 :     Node* node = entry.node;
      96             : 
      97     1254440 :     if (entry.direction == kInputDirection) {
      98      428121 :       if (entry.input != node->input_edges().end()) {
      99      242365 :         Edge edge = *entry.input;
     100             :         Node* input = edge.to();
     101             :         ++(entry.input);
     102      242365 :         if (NodeProperties::IsControlEdge(edge)) {
     103             :           // Visit next control input.
     104      199184 :           if (!Participates(input)) continue;
     105      199184 :           if (GetData(input)->visited) continue;
     106      147078 :           if (GetData(input)->on_stack) {
     107             :             // Found backedge if input is on stack.
     108       40335 :             if (input != entry.parent_node) {
     109         289 :               VisitBackedge(node, input, kInputDirection);
     110             :             }
     111             :           } else {
     112             :             // Push input onto stack.
     113      106743 :             DFSPush(stack, input, node, kInputDirection);
     114             :             VisitPre(input);
     115             :           }
     116             :         }
     117             :         continue;
     118             :       }
     119      185756 :       if (entry.use != node->use_edges().end()) {
     120             :         // Switch direction to uses.
     121      145710 :         entry.direction = kUseDirection;
     122      145710 :         VisitMid(node, kInputDirection);
     123      145707 :         continue;
     124             :       }
     125             :     }
     126             : 
     127      866365 :     if (entry.direction == kUseDirection) {
     128      826363 :       if (entry.use != node->use_edges().end()) {
     129      640609 :         Edge edge = *entry.use;
     130             :         Node* use = edge.from();
     131             :         ++(entry.use);
     132      640609 :         if (NodeProperties::IsControlEdge(edge)) {
     133             :           // Visit next control use.
     134      342844 :           if (!Participates(use)) continue;
     135      186255 :           if (GetData(use)->visited) continue;
     136      185967 :           if (GetData(use)->on_stack) {
     137             :             // Found backedge if use is on stack.
     138      145921 :             if (use != entry.parent_node) {
     139       39178 :               VisitBackedge(node, use, kUseDirection);
     140             :             }
     141             :           } else {
     142             :             // Push use onto stack.
     143       40045 :             DFSPush(stack, use, node, kUseDirection);
     144             :             VisitPre(use);
     145             :           }
     146             :         }
     147             :         continue;
     148             :       }
     149      185754 :       if (entry.input != node->input_edges().end()) {
     150             :         // Switch direction to inputs.
     151       40046 :         entry.direction = kInputDirection;
     152       40046 :         VisitMid(node, kUseDirection);
     153       40046 :         continue;
     154             :       }
     155             :     }
     156             : 
     157             :     // Pop node from stack when done with all inputs and uses.
     158             :     DCHECK(entry.input == node->input_edges().end());
     159             :     DCHECK(entry.use == node->use_edges().end());
     160      185710 :     DFSPop(stack, node);
     161      185751 :     VisitPost(node, entry.parent_node, entry.direction);
     162             :   }
     163       38966 : }
     164             : 
     165      238141 : void ControlEquivalence::DetermineParticipationEnqueue(ZoneQueue<Node*>& queue,
     166             :                                                        Node* node) {
     167      476284 :   if (!Participates(node)) {
     168      185749 :     AllocateData(node);
     169             :     queue.push(node);
     170             :   }
     171      238145 : }
     172             : 
     173             : 
     174       38964 : void ControlEquivalence::DetermineParticipation(Node* exit) {
     175       38964 :   ZoneQueue<Node*> queue(zone_);
     176       38966 :   DetermineParticipationEnqueue(queue, exit);
     177      224717 :   while (!queue.empty()) {  // Breadth-first backwards traversal.
     178      185751 :     Node* node = queue.front();
     179             :     queue.pop();
     180      185749 :     int max = NodeProperties::PastControlIndex(node);
     181      584110 :     for (int i = NodeProperties::FirstControlIndex(node); i < max; i++) {
     182      199178 :       DetermineParticipationEnqueue(queue, node->InputAt(i));
     183             :     }
     184             :   }
     185       38966 : }
     186             : 
     187             : 
     188      185753 : void ControlEquivalence::DFSPush(DFSStack& stack, Node* node, Node* from,
     189             :                                  DFSDirection dir) {
     190             :   DCHECK(Participates(node));
     191             :   DCHECK(!GetData(node)->visited);
     192      185753 :   GetData(node)->on_stack = true;
     193             :   Node::InputEdges::iterator input = node->input_edges().begin();
     194             :   Node::UseEdges::iterator use = node->use_edges().begin();
     195      371508 :   stack.push({dir, input, use, from, node});
     196      185753 : }
     197             : 
     198             : 
     199      185751 : void ControlEquivalence::DFSPop(DFSStack& stack, Node* node) {
     200             :   DCHECK_EQ(stack.top().node, node);
     201      185751 :   GetData(node)->on_stack = false;
     202      185751 :   GetData(node)->visited = true;
     203             :   stack.pop();
     204      185751 : }
     205             : 
     206             : 
     207      371504 : void ControlEquivalence::BracketListDelete(BracketList& blist, Node* to,
     208             :                                            DFSDirection direction) {
     209             :   // TODO(mstarzinger): Optimize this to avoid linear search.
     210      862959 :   for (BracketList::iterator i = blist.begin(); i != blist.end(); /*nop*/) {
     211      491457 :     if (i->to == to && i->direction != direction) {
     212       39465 :       TRACE("  BList erased: {%d->%d}\n", i->from->id(), i->to->id());
     213             :       i = blist.erase(i);
     214             :     } else {
     215             :       ++i;
     216             :     }
     217             :   }
     218      371502 : }
     219             : 
     220             : 
     221      185751 : void ControlEquivalence::BracketListTRACE(BracketList& blist) {
     222      185751 :   if (FLAG_trace_turbo_ceq) {
     223           0 :     TRACE("  BList: ");
     224           0 :     for (Bracket bracket : blist) {
     225           0 :       TRACE("{%d->%d} ", bracket.from->id(), bracket.to->id());
     226             :     }
     227           0 :     TRACE("\n");
     228             :   }
     229      185751 : }
     230             : 
     231             : #undef TRACE
     232             : 
     233             : }  // namespace compiler
     234             : }  // namespace internal
     235      121996 : }  // namespace v8

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