1 //===---- LatencyPriorityQueue.h - A latency-oriented priority queue ------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file declares the LatencyPriorityQueue class, which is a 10 // SchedulingPriorityQueue that schedules using latency information to 11 // reduce the length of the critical path through the basic block. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_CODEGEN_LATENCYPRIORITYQUEUE_H 16 #define LLVM_CODEGEN_LATENCYPRIORITYQUEUE_H 17 18 #include "llvm/CodeGen/ScheduleDAG.h" 19 #include "llvm/Config/llvm-config.h" 20 21 namespace llvm { 22 class LatencyPriorityQueue; 23 24 /// Sorting functions for the Available queue. 25 struct latency_sort { 26 LatencyPriorityQueue *PQ; latency_sortlatency_sort27 explicit latency_sort(LatencyPriorityQueue *pq) : PQ(pq) {} 28 29 bool operator()(const SUnit* LHS, const SUnit* RHS) const; 30 }; 31 32 class LatencyPriorityQueue : public SchedulingPriorityQueue { 33 // SUnits - The SUnits for the current graph. 34 std::vector<SUnit> *SUnits; 35 36 /// NumNodesSolelyBlocking - This vector contains, for every node in the 37 /// Queue, the number of nodes that the node is the sole unscheduled 38 /// predecessor for. This is used as a tie-breaker heuristic for better 39 /// mobility. 40 std::vector<unsigned> NumNodesSolelyBlocking; 41 42 /// Queue - The queue. 43 std::vector<SUnit*> Queue; 44 latency_sort Picker; 45 46 public: LatencyPriorityQueue()47 LatencyPriorityQueue() : Picker(this) { 48 } 49 isBottomUp()50 bool isBottomUp() const override { return false; } 51 initNodes(std::vector<SUnit> & sunits)52 void initNodes(std::vector<SUnit> &sunits) override { 53 SUnits = &sunits; 54 NumNodesSolelyBlocking.resize(SUnits->size(), 0); 55 } 56 addNode(const SUnit * SU)57 void addNode(const SUnit *SU) override { 58 NumNodesSolelyBlocking.resize(SUnits->size(), 0); 59 } 60 updateNode(const SUnit * SU)61 void updateNode(const SUnit *SU) override { 62 } 63 releaseState()64 void releaseState() override { 65 SUnits = nullptr; 66 } 67 getLatency(unsigned NodeNum)68 unsigned getLatency(unsigned NodeNum) const { 69 assert(NodeNum < (*SUnits).size()); 70 return (*SUnits)[NodeNum].getHeight(); 71 } 72 getNumSolelyBlockNodes(unsigned NodeNum)73 unsigned getNumSolelyBlockNodes(unsigned NodeNum) const { 74 assert(NodeNum < NumNodesSolelyBlocking.size()); 75 return NumNodesSolelyBlocking[NodeNum]; 76 } 77 empty()78 bool empty() const override { return Queue.empty(); } 79 80 void push(SUnit *U) override; 81 82 SUnit *pop() override; 83 84 void remove(SUnit *SU) override; 85 86 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 87 LLVM_DUMP_METHOD void dump(ScheduleDAG *DAG) const override; 88 #endif 89 90 // scheduledNode - As nodes are scheduled, we look to see if there are any 91 // successor nodes that have a single unscheduled predecessor. If so, that 92 // single predecessor has a higher priority, since scheduling it will make 93 // the node available. 94 void scheduledNode(SUnit *SU) override; 95 96 private: 97 void AdjustPriorityOfUnscheduledPreds(SUnit *SU); 98 SUnit *getSingleUnscheduledPred(SUnit *SU); 99 }; 100 } 101 102 #endif 103