ART: Refactor SchedulingGraph for consistency and clarity

The CL moves functionality from SchedulingGraph to other classes,
deletes unused code and moves code used for testing to the tests source
file:
1. SchedulingGraph::AddDependency: move checks whether a dependency has
been added to SchedulingNode::Add*Predecessor as it is a SchedulingNode
responsibility to keep a unique set of predecessors.
2. Create SideEffectDependencyAnalysis class. Code doing side effect dependency
analysis is moved from SchedulingGraph into the class.
3. Remove SchedulingGraph::HasImmediate*Dependency methods as there are
SchedulingNode::Has*Dependency methods for such kind of checks.
4. SchedulingGraph::HasImmediate*Dependency(HInstruction,HInstruction) methods
are only used by tests. Their code is moved to a new class TestSchedulingGraph in
the tests source file.

Test: test.py --host --optimizing --jit --gtest
Test: test.py --target --optimizing --jit
Test: run-gtests.sh

Change-Id: Id16eb6e9f8b9706e616dff0ccc1d0353ed968367

1 files changed, 60 insertions, 112 deletions

diff --git a/compiler/optimizing/scheduler.cc b/compiler/optimizing/scheduler.cc
index fdef45ec8b..e5ff8a886a 100644
--- a/compiler/optimizing/scheduler.cc
+++ b/compiler/optimizing/scheduler.cc
@@ -43,34 +43,37 @@ void SchedulingGraph::AddDependency(SchedulingNode* node,
   }
 
   if (is_data_dependency) {
-    if (!HasImmediateDataDependency(node, dependency)) {
-      node->AddDataPredecessor(dependency);
-    }
-  } else if (!HasImmediateOtherDependency(node, dependency)) {
+    node->AddDataPredecessor(dependency);
+  } else {
     node->AddOtherPredecessor(dependency);
   }
 }
 
-static bool MayHaveReorderingDependency(SideEffects node, SideEffects other) {
+bool SideEffectDependencyAnalysis::HasReorderingDependency(const HInstruction* instr1,
+                                                           const HInstruction* instr2) {
+  SideEffects instr1_side_effects = instr1->GetSideEffects();
+  SideEffects instr2_side_effects = instr2->GetSideEffects();
+
   // Read after write.
-  if (node.MayDependOn(other)) {
+  if (instr1_side_effects.MayDependOn(instr2_side_effects)) {
     return true;
   }
 
   // Write after read.
-  if (other.MayDependOn(node)) {
+  if (instr2_side_effects.MayDependOn(instr1_side_effects)) {
     return true;
   }
 
   // Memory write after write.
-  if (node.DoesAnyWrite() && other.DoesAnyWrite()) {
+  if (instr1_side_effects.DoesAnyWrite() && instr2_side_effects.DoesAnyWrite()) {
     return true;
   }
 
   return false;
 }
 
-size_t SchedulingGraph::ArrayAccessHeapLocation(HInstruction* instruction) const {
+size_t SideEffectDependencyAnalysis::MemoryDependencyAnalysis::ArrayAccessHeapLocation(
+    HInstruction* instruction) const {
   DCHECK(heap_location_collector_ != nullptr);
   size_t heap_loc = heap_location_collector_->GetArrayHeapLocation(instruction);
   // This array access should be analyzed and added to HeapLocationCollector before.
@@ -78,19 +81,19 @@ size_t SchedulingGraph::ArrayAccessHeapLocation(HInstruction* instruction) const
   return heap_loc;
 }
 
-bool SchedulingGraph::ArrayAccessMayAlias(HInstruction* node,
-                                          HInstruction* other) const {
+bool SideEffectDependencyAnalysis::MemoryDependencyAnalysis::ArrayAccessMayAlias(
+    HInstruction* instr1, HInstruction* instr2) const {
   DCHECK(heap_location_collector_ != nullptr);
-  size_t node_heap_loc = ArrayAccessHeapLocation(node);
-  size_t other_heap_loc = ArrayAccessHeapLocation(other);
+  size_t instr1_heap_loc = ArrayAccessHeapLocation(instr1);
+  size_t instr2_heap_loc = ArrayAccessHeapLocation(instr2);
 
   // For example: arr[0] and arr[0]
-  if (node_heap_loc == other_heap_loc) {
+  if (instr1_heap_loc == instr2_heap_loc) {
     return true;
   }
 
   // For example: arr[0] and arr[i]
-  if (heap_location_collector_->MayAlias(node_heap_loc, other_heap_loc)) {
+  if (heap_location_collector_->MayAlias(instr1_heap_loc, instr2_heap_loc)) {
     return true;
   }
 
@@ -148,55 +151,55 @@ static const FieldInfo* GetFieldInfo(const HInstruction* instruction) {
   }
 }
 
-size_t SchedulingGraph::FieldAccessHeapLocation(HInstruction* obj, const FieldInfo* field) const {
-  DCHECK(obj != nullptr);
-  DCHECK(field != nullptr);
+size_t SideEffectDependencyAnalysis::MemoryDependencyAnalysis::FieldAccessHeapLocation(
+    const HInstruction* instr) const {
+  DCHECK(instr != nullptr);
+  DCHECK(GetFieldInfo(instr) != nullptr);
   DCHECK(heap_location_collector_ != nullptr);
 
-  size_t heap_loc = heap_location_collector_->GetFieldHeapLocation(obj, field);
+  size_t heap_loc = heap_location_collector_->GetFieldHeapLocation(instr->InputAt(0),
+                                                                   GetFieldInfo(instr));
   // This field access should be analyzed and added to HeapLocationCollector before.
   DCHECK(heap_loc != HeapLocationCollector::kHeapLocationNotFound);
 
   return heap_loc;
 }
 
-bool SchedulingGraph::FieldAccessMayAlias(const HInstruction* node,
-                                          const HInstruction* other) const {
+bool SideEffectDependencyAnalysis::MemoryDependencyAnalysis::FieldAccessMayAlias(
+    const HInstruction* instr1, const HInstruction* instr2) const {
   DCHECK(heap_location_collector_ != nullptr);
 
   // Static and instance field accesses should not alias.
-  if ((IsInstanceFieldAccess(node) && IsStaticFieldAccess(other)) ||
-      (IsStaticFieldAccess(node) && IsInstanceFieldAccess(other))) {
+  if ((IsInstanceFieldAccess(instr1) && IsStaticFieldAccess(instr2)) ||
+      (IsStaticFieldAccess(instr1) && IsInstanceFieldAccess(instr2))) {
     return false;
   }
 
   // If either of the field accesses is unresolved.
-  if (IsUnresolvedFieldAccess(node) || IsUnresolvedFieldAccess(other)) {
+  if (IsUnresolvedFieldAccess(instr1) || IsUnresolvedFieldAccess(instr2)) {
     // Conservatively treat these two accesses may alias.
     return true;
   }
 
   // If both fields accesses are resolved.
-  const FieldInfo* node_field = GetFieldInfo(node);
-  const FieldInfo* other_field = GetFieldInfo(other);
-
-  size_t node_loc = FieldAccessHeapLocation(node->InputAt(0), node_field);
-  size_t other_loc = FieldAccessHeapLocation(other->InputAt(0), other_field);
+  size_t instr1_field_access_heap_loc = FieldAccessHeapLocation(instr1);
+  size_t instr2_field_access_heap_loc = FieldAccessHeapLocation(instr2);
 
-  if (node_loc == other_loc) {
+  if (instr1_field_access_heap_loc == instr2_field_access_heap_loc) {
     return true;
   }
 
-  if (!heap_location_collector_->MayAlias(node_loc, other_loc)) {
+  if (!heap_location_collector_->MayAlias(instr1_field_access_heap_loc,
+                                          instr2_field_access_heap_loc)) {
     return false;
   }
 
   return true;
 }
 
-bool SchedulingGraph::HasMemoryDependency(HInstruction* node,
-                                          HInstruction* other) const {
-  if (!MayHaveReorderingDependency(node->GetSideEffects(), other->GetSideEffects())) {
+bool SideEffectDependencyAnalysis::MemoryDependencyAnalysis::HasMemoryDependency(
+    HInstruction* instr1, HInstruction* instr2) const {
+  if (!HasReorderingDependency(instr1, instr2)) {
     return false;
   }
 
@@ -208,35 +211,35 @@ bool SchedulingGraph::HasMemoryDependency(HInstruction* node,
     return true;
   }
 
-  if (IsArrayAccess(node) && IsArrayAccess(other)) {
-    return ArrayAccessMayAlias(node, other);
+  if (IsArrayAccess(instr1) && IsArrayAccess(instr2)) {
+    return ArrayAccessMayAlias(instr1, instr2);
   }
-  if (IsFieldAccess(node) && IsFieldAccess(other)) {
-    return FieldAccessMayAlias(node, other);
+  if (IsFieldAccess(instr1) && IsFieldAccess(instr2)) {
+    return FieldAccessMayAlias(instr1, instr2);
   }
 
   // TODO(xueliang): LSA to support alias analysis among HVecLoad, HVecStore and ArrayAccess
-  if (node->IsVecMemoryOperation() && other->IsVecMemoryOperation()) {
+  if (instr1->IsVecMemoryOperation() && instr2->IsVecMemoryOperation()) {
     return true;
   }
-  if (node->IsVecMemoryOperation() && IsArrayAccess(other)) {
+  if (instr1->IsVecMemoryOperation() && IsArrayAccess(instr2)) {
     return true;
   }
-  if (IsArrayAccess(node) && other->IsVecMemoryOperation()) {
+  if (IsArrayAccess(instr1) && instr2->IsVecMemoryOperation()) {
     return true;
   }
 
   // Heap accesses of different kinds should not alias.
-  if (IsArrayAccess(node) && IsFieldAccess(other)) {
+  if (IsArrayAccess(instr1) && IsFieldAccess(instr2)) {
     return false;
   }
-  if (IsFieldAccess(node) && IsArrayAccess(other)) {
+  if (IsFieldAccess(instr1) && IsArrayAccess(instr2)) {
     return false;
   }
-  if (node->IsVecMemoryOperation() && IsFieldAccess(other)) {
+  if (instr1->IsVecMemoryOperation() && IsFieldAccess(instr2)) {
     return false;
   }
-  if (IsFieldAccess(node) && other->IsVecMemoryOperation()) {
+  if (IsFieldAccess(instr1) && instr2->IsVecMemoryOperation()) {
     return false;
   }
 
@@ -245,15 +248,15 @@ bool SchedulingGraph::HasMemoryDependency(HInstruction* node,
   return true;
 }
 
-bool SchedulingGraph::HasExceptionDependency(const HInstruction* node,
-                                             const HInstruction* other) const {
-  if (other->CanThrow() && node->GetSideEffects().DoesAnyWrite()) {
+bool SideEffectDependencyAnalysis::HasExceptionDependency(const HInstruction* instr1,
+                                                          const HInstruction* instr2) {
+  if (instr2->CanThrow() && instr1->GetSideEffects().DoesAnyWrite()) {
     return true;
   }
-  if (other->GetSideEffects().DoesAnyWrite() && node->CanThrow()) {
+  if (instr2->GetSideEffects().DoesAnyWrite() && instr1->CanThrow()) {
     return true;
   }
-  if (other->CanThrow() && node->CanThrow()) {
+  if (instr2->CanThrow() && instr1->CanThrow()) {
     return true;
   }
 
@@ -262,24 +265,6 @@ bool SchedulingGraph::HasExceptionDependency(const HInstruction* node,
   return false;
 }
 
-// Check whether `node` depends on `other`, taking into account `SideEffect`
-// information and `CanThrow` information.
-bool SchedulingGraph::HasSideEffectDependency(HInstruction* node,
-                                              HInstruction* other) const {
-  if (HasMemoryDependency(node, other)) {
-    return true;
-  }
-
-  // Even if above memory dependency check has passed, it is still necessary to
-  // check dependencies between instructions that can throw and instructions
-  // that write to memory.
-  if (HasExceptionDependency(node, other)) {
-    return true;
-  }
-
-  return false;
-}
-
 // Check if the specified instruction is a better candidate which more likely will
 // have other instructions depending on it.
 static bool IsBetterCandidateWithMoreLikelyDependencies(HInstruction* new_candidate,
@@ -297,8 +282,9 @@ static bool IsBetterCandidateWithMoreLikelyDependencies(HInstruction* new_candid
   }
 }
 
-void SchedulingGraph::AddDependencies(HInstruction* instruction, bool is_scheduling_barrier) {
-  SchedulingNode* instruction_node = GetNode(instruction);
+void SchedulingGraph::AddDependencies(SchedulingNode* instruction_node,
+                                      bool is_scheduling_barrier) {
+  HInstruction* instruction = instruction_node->GetInstruction();
 
   // Define-use dependencies.
   for (const HUseListNode<HInstruction*>& use : instruction->GetUses()) {
@@ -354,12 +340,12 @@ void SchedulingGraph::AddDependencies(HInstruction* instruction, bool is_schedul
       if (other_node->IsSchedulingBarrier()) {
         // We have reached a scheduling barrier so we can stop further
         // processing.
-        DCHECK(HasImmediateOtherDependency(other_node, instruction_node));
+        DCHECK(other_node->HasOtherDependency(instruction_node));
         break;
       }
-      if (HasSideEffectDependency(other, instruction)) {
+      if (side_effect_dependency_analysis_.HasSideEffectDependency(other, instruction)) {
         if (dep_chain_candidate != nullptr &&
-            HasSideEffectDependency(other, dep_chain_candidate)) {
+            side_effect_dependency_analysis_.HasSideEffectDependency(other, dep_chain_candidate)) {
           // Skip an explicit dependency to reduce memory usage, rely on the transitive dependency.
         } else {
           AddOtherDependency(other_node, instruction_node);
@@ -388,44 +374,6 @@ void SchedulingGraph::AddDependencies(HInstruction* instruction, bool is_schedul
   }
 }
 
-bool SchedulingGraph::HasImmediateDataDependency(const SchedulingNode* node,
-                                                 const SchedulingNode* other) const {
-  return ContainsElement(node->GetDataPredecessors(), other);
-}
-
-bool SchedulingGraph::HasImmediateDataDependency(const HInstruction* instruction,
-                                                 const HInstruction* other_instruction) const {
-  const SchedulingNode* node = GetNode(instruction);
-  const SchedulingNode* other = GetNode(other_instruction);
-  if (node == nullptr || other == nullptr) {
-    // Both instructions must be in current basic block, i.e. the SchedulingGraph can see their
-    // corresponding SchedulingNode in the graph, and tell whether there is a dependency.
-    // Otherwise there is no dependency from SchedulingGraph's perspective, for example,
-    // instruction and other_instruction are in different basic blocks.
-    return false;
-  }
-  return HasImmediateDataDependency(node, other);
-}
-
-bool SchedulingGraph::HasImmediateOtherDependency(const SchedulingNode* node,
-                                                  const SchedulingNode* other) const {
-  return ContainsElement(node->GetOtherPredecessors(), other);
-}
-
-bool SchedulingGraph::HasImmediateOtherDependency(const HInstruction* instruction,
-                                                  const HInstruction* other_instruction) const {
-  const SchedulingNode* node = GetNode(instruction);
-  const SchedulingNode* other = GetNode(other_instruction);
-  if (node == nullptr || other == nullptr) {
-    // Both instructions must be in current basic block, i.e. the SchedulingGraph can see their
-    // corresponding SchedulingNode in the graph, and tell whether there is a dependency.
-    // Otherwise there is no dependency from SchedulingGraph's perspective, for example,
-    // instruction and other_instruction are in different basic blocks.
-    return false;
-  }
-  return HasImmediateOtherDependency(node, other);
-}
-
 static const std::string InstructionTypeId(const HInstruction* instruction) {
   return DataType::TypeId(instruction->GetType()) + std::to_string(instruction->GetId());
 }
@@ -594,7 +542,7 @@ void HScheduler::Schedule(HBasicBlock* block,
   ScopedArenaVector<SchedulingNode*> scheduling_nodes(allocator.Adapter(kArenaAllocScheduler));
 
   // Build the scheduling graph.
-  SchedulingGraph scheduling_graph(this, &allocator, heap_location_collector);
+  SchedulingGraph scheduling_graph(&allocator, heap_location_collector);
   for (HBackwardInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
     HInstruction* instruction = it.Current();
     CHECK_EQ(instruction->GetBlock(), block)