// Copyright 2014 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "src/compiler/common-operator-reducer.h" #include <algorithm> #include "src/compiler/common-operator.h" #include "src/compiler/graph.h" #include "src/compiler/machine-operator.h" #include "src/compiler/node.h" #include "src/compiler/node-matchers.h" #include "src/compiler/node-properties.h" namespace v8 { namespace internal { namespace compiler { namespace { enum class Decision { kUnknown, kTrue, kFalse }; Decision DecideCondition(Node* const cond) { switch (cond->opcode()) { case IrOpcode::kInt32Constant: { Int32Matcher mcond(cond); return mcond.Value() ? Decision::kTrue : Decision::kFalse; } case IrOpcode::kInt64Constant: { Int64Matcher mcond(cond); return mcond.Value() ? Decision::kTrue : Decision::kFalse; } case IrOpcode::kHeapConstant: { HeapObjectMatcher mcond(cond); return mcond.Value().handle()->BooleanValue() ? Decision::kTrue : Decision::kFalse; } default: return Decision::kUnknown; } } } // namespace CommonOperatorReducer::CommonOperatorReducer(Editor* editor, Graph* graph, CommonOperatorBuilder* common, MachineOperatorBuilder* machine) : AdvancedReducer(editor), graph_(graph), common_(common), machine_(machine), dead_(graph->NewNode(common->Dead())) {} Reduction CommonOperatorReducer::Reduce(Node* node) { switch (node->opcode()) { case IrOpcode::kBranch: return ReduceBranch(node); case IrOpcode::kMerge: return ReduceMerge(node); case IrOpcode::kEffectPhi: return ReduceEffectPhi(node); case IrOpcode::kPhi: return ReducePhi(node); case IrOpcode::kReturn: return ReduceReturn(node); case IrOpcode::kSelect: return ReduceSelect(node); default: break; } return NoChange(); } Reduction CommonOperatorReducer::ReduceBranch(Node* node) { DCHECK_EQ(IrOpcode::kBranch, node->opcode()); Node* const cond = node->InputAt(0); // Swap IfTrue/IfFalse on {branch} if {cond} is a BooleanNot and use the input // to BooleanNot as new condition for {branch}. Note we assume that {cond} was // already properly optimized before we get here (as guaranteed by the graph // reduction logic). if (cond->opcode() == IrOpcode::kBooleanNot) { for (Node* const use : node->uses()) { switch (use->opcode()) { case IrOpcode::kIfTrue: use->set_op(common()->IfFalse()); break; case IrOpcode::kIfFalse: use->set_op(common()->IfTrue()); break; default: UNREACHABLE(); } } // Update the condition of {branch}. No need to mark the uses for revisit, // since we tell the graph reducer that the {branch} was changed and the // graph reduction logic will ensure that the uses are revisited properly. node->ReplaceInput(0, cond->InputAt(0)); // Negate the hint for {branch}. node->set_op(common()->Branch(NegateBranchHint(BranchHintOf(node->op())))); return Changed(node); } Decision const decision = DecideCondition(cond); if (decision == Decision::kUnknown) return NoChange(); Node* const control = node->InputAt(1); for (Node* const use : node->uses()) { switch (use->opcode()) { case IrOpcode::kIfTrue: Replace(use, (decision == Decision::kTrue) ? control : dead()); break; case IrOpcode::kIfFalse: Replace(use, (decision == Decision::kFalse) ? control : dead()); break; default: UNREACHABLE(); } } return Replace(dead()); } Reduction CommonOperatorReducer::ReduceMerge(Node* node) { DCHECK_EQ(IrOpcode::kMerge, node->opcode()); // // Check if this is a merge that belongs to an unused diamond, which means // that: // // a) the {Merge} has no {Phi} or {EffectPhi} uses, and // b) the {Merge} has two inputs, one {IfTrue} and one {IfFalse}, which are // both owned by the Merge, and // c) and the {IfTrue} and {IfFalse} nodes point to the same {Branch}. // if (node->InputCount() == 2) { for (Node* const use : node->uses()) { if (IrOpcode::IsPhiOpcode(use->opcode())) return NoChange(); } Node* if_true = node->InputAt(0); Node* if_false = node->InputAt(1); if (if_true->opcode() != IrOpcode::kIfTrue) std::swap(if_true, if_false); if (if_true->opcode() == IrOpcode::kIfTrue && if_false->opcode() == IrOpcode::kIfFalse && if_true->InputAt(0) == if_false->InputAt(0) && if_true->OwnedBy(node) && if_false->OwnedBy(node)) { Node* const branch = if_true->InputAt(0); DCHECK_EQ(IrOpcode::kBranch, branch->opcode()); DCHECK(branch->OwnedBy(if_true, if_false)); Node* const control = branch->InputAt(1); // Mark the {branch} as {Dead}. branch->set_op(common()->Dead()); branch->TrimInputCount(0); return Replace(control); } } return NoChange(); } Reduction CommonOperatorReducer::ReduceEffectPhi(Node* node) { DCHECK_EQ(IrOpcode::kEffectPhi, node->opcode()); int const input_count = node->InputCount() - 1; DCHECK_LE(1, input_count); Node* const merge = node->InputAt(input_count); DCHECK(IrOpcode::IsMergeOpcode(merge->opcode())); DCHECK_EQ(input_count, merge->InputCount()); Node* const effect = node->InputAt(0); DCHECK_NE(node, effect); for (int i = 1; i < input_count; ++i) { Node* const input = node->InputAt(i); if (input == node) { // Ignore redundant inputs. DCHECK_EQ(IrOpcode::kLoop, merge->opcode()); continue; } if (input != effect) return NoChange(); } // We might now be able to further reduce the {merge} node. Revisit(merge); return Replace(effect); } Reduction CommonOperatorReducer::ReducePhi(Node* node) { DCHECK_EQ(IrOpcode::kPhi, node->opcode()); int const input_count = node->InputCount() - 1; DCHECK_LE(1, input_count); Node* const merge = node->InputAt(input_count); DCHECK(IrOpcode::IsMergeOpcode(merge->opcode())); DCHECK_EQ(input_count, merge->InputCount()); if (input_count == 2) { Node* vtrue = node->InputAt(0); Node* vfalse = node->InputAt(1); Node* if_true = merge->InputAt(0); Node* if_false = merge->InputAt(1); if (if_true->opcode() != IrOpcode::kIfTrue) { std::swap(if_true, if_false); std::swap(vtrue, vfalse); } if (if_true->opcode() == IrOpcode::kIfTrue && if_false->opcode() == IrOpcode::kIfFalse && if_true->InputAt(0) == if_false->InputAt(0)) { Node* const branch = if_true->InputAt(0); Node* const cond = branch->InputAt(0); if (cond->opcode() == IrOpcode::kFloat32LessThan) { Float32BinopMatcher mcond(cond); if (mcond.left().Is(0.0) && mcond.right().Equals(vtrue) && vfalse->opcode() == IrOpcode::kFloat32Sub) { Float32BinopMatcher mvfalse(vfalse); if (mvfalse.left().IsZero() && mvfalse.right().Equals(vtrue)) { // We might now be able to further reduce the {merge} node. Revisit(merge); return Change(node, machine()->Float32Abs(), vtrue); } } if (mcond.left().Equals(vtrue) && mcond.right().Equals(vfalse) && machine()->Float32Min().IsSupported()) { // We might now be able to further reduce the {merge} node. Revisit(merge); return Change(node, machine()->Float32Min().op(), vtrue, vfalse); } else if (mcond.left().Equals(vfalse) && mcond.right().Equals(vtrue) && machine()->Float32Max().IsSupported()) { // We might now be able to further reduce the {merge} node. Revisit(merge); return Change(node, machine()->Float32Max().op(), vtrue, vfalse); } } else if (cond->opcode() == IrOpcode::kFloat64LessThan) { Float64BinopMatcher mcond(cond); if (mcond.left().Is(0.0) && mcond.right().Equals(vtrue) && vfalse->opcode() == IrOpcode::kFloat64Sub) { Float64BinopMatcher mvfalse(vfalse); if (mvfalse.left().IsZero() && mvfalse.right().Equals(vtrue)) { // We might now be able to further reduce the {merge} node. Revisit(merge); return Change(node, machine()->Float64Abs(), vtrue); } } if (mcond.left().Equals(vtrue) && mcond.right().Equals(vfalse) && machine()->Float64Min().IsSupported()) { // We might now be able to further reduce the {merge} node. Revisit(merge); return Change(node, machine()->Float64Min().op(), vtrue, vfalse); } else if (mcond.left().Equals(vfalse) && mcond.right().Equals(vtrue) && machine()->Float64Max().IsSupported()) { // We might now be able to further reduce the {merge} node. Revisit(merge); return Change(node, machine()->Float64Max().op(), vtrue, vfalse); } } } } Node* const value = node->InputAt(0); DCHECK_NE(node, value); for (int i = 1; i < input_count; ++i) { Node* const input = node->InputAt(i); if (input == node) { // Ignore redundant inputs. DCHECK_EQ(IrOpcode::kLoop, merge->opcode()); continue; } if (input != value) return NoChange(); } // We might now be able to further reduce the {merge} node. Revisit(merge); return Replace(value); } Reduction CommonOperatorReducer::ReduceReturn(Node* node) { DCHECK_EQ(IrOpcode::kReturn, node->opcode()); Node* const value = node->InputAt(0); Node* const effect = node->InputAt(1); Node* const control = node->InputAt(2); if (value->opcode() == IrOpcode::kPhi && NodeProperties::GetControlInput(value) == control && effect->opcode() == IrOpcode::kEffectPhi && NodeProperties::GetControlInput(effect) == control && control->opcode() == IrOpcode::kMerge) { int const control_input_count = control->InputCount(); DCHECK_NE(0, control_input_count); DCHECK_EQ(control_input_count, value->InputCount() - 1); DCHECK_EQ(control_input_count, effect->InputCount() - 1); Node* const end = graph()->end(); DCHECK_EQ(IrOpcode::kEnd, end->opcode()); DCHECK_NE(0, end->InputCount()); for (int i = 0; i < control_input_count; ++i) { // Create a new {Return} and connect it to {end}. We don't need to mark // {end} as revisit, because we mark {node} as {Dead} below, which was // previously connected to {end}, so we know for sure that at some point // the reducer logic will visit {end} again. Node* ret = graph()->NewNode(common()->Return(), value->InputAt(i), effect->InputAt(i), control->InputAt(i)); end->set_op(common()->End(end->InputCount() + 1)); end->AppendInput(graph()->zone(), ret); } // Mark the merge {control} and return {node} as {dead}. Replace(control, dead()); return Replace(dead()); } return NoChange(); } Reduction CommonOperatorReducer::ReduceSelect(Node* node) { DCHECK_EQ(IrOpcode::kSelect, node->opcode()); Node* const cond = node->InputAt(0); Node* const vtrue = node->InputAt(1); Node* const vfalse = node->InputAt(2); if (vtrue == vfalse) return Replace(vtrue); switch (DecideCondition(cond)) { case Decision::kTrue: return Replace(vtrue); case Decision::kFalse: return Replace(vfalse); case Decision::kUnknown: break; } switch (cond->opcode()) { case IrOpcode::kFloat32LessThan: { Float32BinopMatcher mcond(cond); if (mcond.left().Is(0.0) && mcond.right().Equals(vtrue) && vfalse->opcode() == IrOpcode::kFloat32Sub) { Float32BinopMatcher mvfalse(vfalse); if (mvfalse.left().IsZero() && mvfalse.right().Equals(vtrue)) { return Change(node, machine()->Float32Abs(), vtrue); } } if (mcond.left().Equals(vtrue) && mcond.right().Equals(vfalse) && machine()->Float32Min().IsSupported()) { return Change(node, machine()->Float32Min().op(), vtrue, vfalse); } else if (mcond.left().Equals(vfalse) && mcond.right().Equals(vtrue) && machine()->Float32Max().IsSupported()) { return Change(node, machine()->Float32Max().op(), vtrue, vfalse); } break; } case IrOpcode::kFloat64LessThan: { Float64BinopMatcher mcond(cond); if (mcond.left().Is(0.0) && mcond.right().Equals(vtrue) && vfalse->opcode() == IrOpcode::kFloat64Sub) { Float64BinopMatcher mvfalse(vfalse); if (mvfalse.left().IsZero() && mvfalse.right().Equals(vtrue)) { return Change(node, machine()->Float64Abs(), vtrue); } } if (mcond.left().Equals(vtrue) && mcond.right().Equals(vfalse) && machine()->Float64Min().IsSupported()) { return Change(node, machine()->Float64Min().op(), vtrue, vfalse); } else if (mcond.left().Equals(vfalse) && mcond.right().Equals(vtrue) && machine()->Float64Max().IsSupported()) { return Change(node, machine()->Float64Max().op(), vtrue, vfalse); } break; } default: break; } return NoChange(); } Reduction CommonOperatorReducer::Change(Node* node, Operator const* op, Node* a) { node->set_op(op); node->ReplaceInput(0, a); node->TrimInputCount(1); return Changed(node); } Reduction CommonOperatorReducer::Change(Node* node, Operator const* op, Node* a, Node* b) { node->set_op(op); node->ReplaceInput(0, a); node->ReplaceInput(1, b); node->TrimInputCount(2); return Changed(node); } } // namespace compiler } // namespace internal } // namespace v8