| // 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 { |
| |
| Decision DecideCondition(JSHeapBroker* broker, Node* const cond) { |
| switch (cond->opcode()) { |
| case IrOpcode::kInt32Constant: { |
| Int32Matcher mcond(cond); |
| return mcond.Value() ? Decision::kTrue : Decision::kFalse; |
| } |
| case IrOpcode::kHeapConstant: { |
| HeapObjectMatcher mcond(cond); |
| return mcond.Ref(broker).BooleanValue() ? Decision::kTrue |
| : Decision::kFalse; |
| } |
| default: |
| return Decision::kUnknown; |
| } |
| } |
| |
| } // namespace |
| |
| CommonOperatorReducer::CommonOperatorReducer(Editor* editor, Graph* graph, |
| JSHeapBroker* broker, |
| CommonOperatorBuilder* common, |
| MachineOperatorBuilder* machine, |
| Zone* temp_zone) |
| : AdvancedReducer(editor), |
| graph_(graph), |
| broker_(broker), |
| common_(common), |
| machine_(machine), |
| dead_(graph->NewNode(common->Dead())), |
| zone_(temp_zone) { |
| NodeProperties::SetType(dead_, Type::None()); |
| } |
| |
| Reduction CommonOperatorReducer::Reduce(Node* node) { |
| DisallowHeapAccess no_heap_access; |
| switch (node->opcode()) { |
| case IrOpcode::kBranch: |
| return ReduceBranch(node); |
| case IrOpcode::kDeoptimizeIf: |
| case IrOpcode::kDeoptimizeUnless: |
| return ReduceDeoptimizeConditional(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); |
| case IrOpcode::kSwitch: |
| return ReduceSwitch(node); |
| case IrOpcode::kStaticAssert: |
| return ReduceStaticAssert(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). The same applies if {cond} is a Select acting as boolean |
| // not (i.e. true being returned in the false case and vice versa). |
| if (cond->opcode() == IrOpcode::kBooleanNot || |
| (cond->opcode() == IrOpcode::kSelect && |
| DecideCondition(broker(), cond->InputAt(1)) == Decision::kFalse && |
| DecideCondition(broker(), cond->InputAt(2)) == Decision::kTrue)) { |
| for (Node* const use : node->uses()) { |
| switch (use->opcode()) { |
| case IrOpcode::kIfTrue: |
| NodeProperties::ChangeOp(use, common()->IfFalse()); |
| break; |
| case IrOpcode::kIfFalse: |
| NodeProperties::ChangeOp(use, 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}. |
| NodeProperties::ChangeOp( |
| node, common()->Branch(NegateBranchHint(BranchHintOf(node->op())))); |
| return Changed(node); |
| } |
| Decision const decision = DecideCondition(broker(), 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::ReduceDeoptimizeConditional(Node* node) { |
| DCHECK(node->opcode() == IrOpcode::kDeoptimizeIf || |
| node->opcode() == IrOpcode::kDeoptimizeUnless); |
| bool condition_is_true = node->opcode() == IrOpcode::kDeoptimizeUnless; |
| DeoptimizeParameters p = DeoptimizeParametersOf(node->op()); |
| Node* condition = NodeProperties::GetValueInput(node, 0); |
| Node* frame_state = NodeProperties::GetValueInput(node, 1); |
| Node* effect = NodeProperties::GetEffectInput(node); |
| Node* control = NodeProperties::GetControlInput(node); |
| // Swap DeoptimizeIf/DeoptimizeUnless on {node} if {cond} is a BooleaNot |
| // and use the input to BooleanNot as new condition for {node}. Note we |
| // assume that {cond} was already properly optimized before we get here |
| // (as guaranteed by the graph reduction logic). |
| if (condition->opcode() == IrOpcode::kBooleanNot) { |
| NodeProperties::ReplaceValueInput(node, condition->InputAt(0), 0); |
| NodeProperties::ChangeOp( |
| node, |
| condition_is_true |
| ? common()->DeoptimizeIf(p.kind(), p.reason(), p.feedback()) |
| : common()->DeoptimizeUnless(p.kind(), p.reason(), p.feedback())); |
| return Changed(node); |
| } |
| Decision const decision = DecideCondition(broker(), condition); |
| if (decision == Decision::kUnknown) return NoChange(); |
| if (condition_is_true == (decision == Decision::kTrue)) { |
| ReplaceWithValue(node, dead(), effect, control); |
| } else { |
| control = graph()->NewNode( |
| common()->Deoptimize(p.kind(), p.reason(), p.feedback()), frame_state, |
| effect, control); |
| // TODO(bmeurer): This should be on the AdvancedReducer somehow. |
| NodeProperties::MergeControlToEnd(graph(), common(), control); |
| Revisit(graph()->end()); |
| } |
| 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->TrimInputCount(0); |
| NodeProperties::ChangeOp(branch, common()->Dead()); |
| return Replace(control); |
| } |
| } |
| return NoChange(); |
| } |
| |
| |
| Reduction CommonOperatorReducer::ReduceEffectPhi(Node* node) { |
| DCHECK_EQ(IrOpcode::kEffectPhi, node->opcode()); |
| Node::Inputs inputs = node->inputs(); |
| int const effect_input_count = inputs.count() - 1; |
| DCHECK_LE(1, effect_input_count); |
| Node* const merge = inputs[effect_input_count]; |
| DCHECK(IrOpcode::IsMergeOpcode(merge->opcode())); |
| DCHECK_EQ(effect_input_count, merge->InputCount()); |
| Node* const effect = inputs[0]; |
| DCHECK_NE(node, effect); |
| for (int i = 1; i < effect_input_count; ++i) { |
| Node* const input = inputs[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()); |
| Node::Inputs inputs = node->inputs(); |
| int const value_input_count = inputs.count() - 1; |
| DCHECK_LE(1, value_input_count); |
| Node* const merge = inputs[value_input_count]; |
| DCHECK(IrOpcode::IsMergeOpcode(merge->opcode())); |
| DCHECK_EQ(value_input_count, merge->InputCount()); |
| if (value_input_count == 2) { |
| Node* vtrue = inputs[0]; |
| Node* vfalse = inputs[1]; |
| Node::Inputs merge_inputs = merge->inputs(); |
| Node* if_true = merge_inputs[0]; |
| Node* if_false = merge_inputs[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); |
| // Check that the branch is not dead already. |
| if (branch->opcode() != IrOpcode::kBranch) return NoChange(); |
| 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); |
| } |
| } |
| } 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); |
| } |
| } |
| } |
| } |
| } |
| Node* const value = inputs[0]; |
| DCHECK_NE(node, value); |
| for (int i = 1; i < value_input_count; ++i) { |
| Node* const input = inputs[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* effect = NodeProperties::GetEffectInput(node); |
| if (effect->opcode() == IrOpcode::kCheckpoint) { |
| // Any {Return} node can never be used to insert a deoptimization point, |
| // hence checkpoints can be cut out of the effect chain flowing into it. |
| effect = NodeProperties::GetEffectInput(effect); |
| NodeProperties::ReplaceEffectInput(node, effect); |
| Reduction const reduction = ReduceReturn(node); |
| return reduction.Changed() ? reduction : Changed(node); |
| } |
| // TODO(ahaas): Extend the reduction below to multiple return values. |
| if (ValueInputCountOfReturn(node->op()) != 1) { |
| return NoChange(); |
| } |
| Node* pop_count = NodeProperties::GetValueInput(node, 0); |
| Node* value = NodeProperties::GetValueInput(node, 1); |
| Node* control = NodeProperties::GetControlInput(node); |
| if (value->opcode() == IrOpcode::kPhi && |
| NodeProperties::GetControlInput(value) == control && |
| control->opcode() == IrOpcode::kMerge) { |
| // This optimization pushes {Return} nodes through merges. It checks that |
| // the return value is actually a {Phi} and the return control dependency |
| // is the {Merge} to which the {Phi} belongs. |
| |
| // Value1 ... ValueN Control1 ... ControlN |
| // ^ ^ ^ ^ |
| // | | | | |
| // +----+-----+ +------+-----+ |
| // | | |
| // Phi --------------> Merge |
| // ^ ^ |
| // | | |
| // | +-----------------+ |
| // | | |
| // Return -----> Effect |
| // ^ |
| // | |
| // End |
| |
| // Now the effect input to the {Return} node can be either an {EffectPhi} |
| // hanging off the same {Merge}, or the effect chain doesn't depend on the |
| // {Phi} or the {Merge}, in which case we know that the effect input must |
| // somehow dominate all merged branches. |
| |
| Node::Inputs control_inputs = control->inputs(); |
| Node::Inputs value_inputs = value->inputs(); |
| DCHECK_NE(0, control_inputs.count()); |
| DCHECK_EQ(control_inputs.count(), value_inputs.count() - 1); |
| DCHECK_EQ(IrOpcode::kEnd, graph()->end()->opcode()); |
| DCHECK_NE(0, graph()->end()->InputCount()); |
| if (control->OwnedBy(node, value) && value->OwnedBy(node)) { |
| for (int i = 0; i < control_inputs.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(node->op(), pop_count, value_inputs[i], |
| effect, control_inputs[i]); |
| NodeProperties::MergeControlToEnd(graph(), common(), ret); |
| } |
| // Mark the Merge {control} and Return {node} as {dead}. |
| Replace(control, dead()); |
| return Replace(dead()); |
| } else if (effect->opcode() == IrOpcode::kEffectPhi && |
| NodeProperties::GetControlInput(effect) == control) { |
| Node::Inputs effect_inputs = effect->inputs(); |
| DCHECK_EQ(control_inputs.count(), effect_inputs.count() - 1); |
| for (int i = 0; i < control_inputs.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(node->op(), pop_count, value_inputs[i], |
| effect_inputs[i], control_inputs[i]); |
| NodeProperties::MergeControlToEnd(graph(), common(), 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(broker(), 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); |
| } |
| } |
| 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); |
| } |
| } |
| break; |
| } |
| default: |
| break; |
| } |
| return NoChange(); |
| } |
| |
| Reduction CommonOperatorReducer::ReduceSwitch(Node* node) { |
| DCHECK_EQ(IrOpcode::kSwitch, node->opcode()); |
| Node* const switched_value = node->InputAt(0); |
| Node* const control = node->InputAt(1); |
| |
| // Attempt to constant match the switched value against the IfValue cases. If |
| // no case matches, then use the IfDefault. We don't bother marking |
| // non-matching cases as dead code (same for an unused IfDefault), because the |
| // Switch itself will be marked as dead code. |
| Int32Matcher mswitched(switched_value); |
| if (mswitched.HasValue()) { |
| bool matched = false; |
| |
| size_t const projection_count = node->op()->ControlOutputCount(); |
| Node** projections = zone_->NewArray<Node*>(projection_count); |
| NodeProperties::CollectControlProjections(node, projections, |
| projection_count); |
| for (size_t i = 0; i < projection_count - 1; i++) { |
| Node* if_value = projections[i]; |
| DCHECK_EQ(IrOpcode::kIfValue, if_value->opcode()); |
| const IfValueParameters& p = IfValueParametersOf(if_value->op()); |
| if (p.value() == mswitched.Value()) { |
| matched = true; |
| Replace(if_value, control); |
| break; |
| } |
| } |
| if (!matched) { |
| Node* if_default = projections[projection_count - 1]; |
| DCHECK_EQ(IrOpcode::kIfDefault, if_default->opcode()); |
| Replace(if_default, control); |
| } |
| return Replace(dead()); |
| } |
| return NoChange(); |
| } |
| |
| Reduction CommonOperatorReducer::ReduceStaticAssert(Node* node) { |
| DCHECK_EQ(IrOpcode::kStaticAssert, node->opcode()); |
| Node* const cond = node->InputAt(0); |
| Decision decision = DecideCondition(broker(), cond); |
| if (decision == Decision::kTrue) { |
| RelaxEffectsAndControls(node); |
| return Changed(node); |
| } else { |
| return NoChange(); |
| } |
| } |
| |
| Reduction CommonOperatorReducer::Change(Node* node, Operator const* op, |
| Node* a) { |
| node->ReplaceInput(0, a); |
| node->TrimInputCount(1); |
| NodeProperties::ChangeOp(node, op); |
| return Changed(node); |
| } |
| |
| |
| Reduction CommonOperatorReducer::Change(Node* node, Operator const* op, Node* a, |
| Node* b) { |
| node->ReplaceInput(0, a); |
| node->ReplaceInput(1, b); |
| node->TrimInputCount(2); |
| NodeProperties::ChangeOp(node, op); |
| return Changed(node); |
| } |
| |
| } // namespace compiler |
| } // namespace internal |
| } // namespace v8 |
