[turbofan] Effect linearization after representation inference.

This introduces a compiler pass that schedules the graph and re-wires effect chain according to the schedule. It also connects allocating representation changes to the effect chain, and removes the BeginRegion and EndRegion nodes - they should not be needed anymore because all effectful nodes should be already wired-in.

This is an intermediate CL - the next step is to move lowering of the Change*ToTaggedEffect nodes to StateEffectIntroduction so that we do not have to introduce the effectful versions of nodes.

Review URL: https://codereview.chromium.org/1849603002

Cr-Commit-Position: refs/heads/master@{#35565}

BUILD.gn

@@ -812,6 +812,8 @@ source_set("v8_base") {
     "src/compiler/dead-code-elimination.cc",
     "src/compiler/dead-code-elimination.h",
     "src/compiler/diamond.h",
+    "src/compiler/effect-control-linearizer.cc",
+    "src/compiler/effect-control-linearizer.h",
     "src/compiler/escape-analysis-reducer.cc",
     "src/compiler/escape-analysis-reducer.h",
     "src/compiler/escape-analysis.cc",

src/compiler.h

@@ -158,7 +158,8 @@ class CompilationInfo {
     kSplittingEnabled = 1 << 13,
     kDeoptimizationEnabled = 1 << 14,
     kSourcePositionsEnabled = 1 << 15,
-    kBailoutOnUninitialized = 1 << 16,
+    kEffectSchedulingEnabled = 1 << 16,
+    kBailoutOnUninitialized = 1 << 17,
   };
 
   CompilationInfo(ParseInfo* parse_info, Handle<JSFunction> closure);
@@ -277,6 +278,12 @@ class CompilationInfo {
     return GetFlag(kDeoptimizationEnabled);
   }
 
+  void MarkAsEffectSchedulingEnabled() { SetFlag(kEffectSchedulingEnabled); }
+
+  bool is_effect_scheduling_enabled() const {
+    return GetFlag(kEffectSchedulingEnabled);
+  }
+
   void MarkAsSourcePositionsEnabled() { SetFlag(kSourcePositionsEnabled); }
 
   bool is_source_positions_enabled() const {

src/compiler/effect-control-linearizer.h

+// Copyright 2016 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.
+
+#ifndef V8_COMPILER_EFFECT_CONTROL_LINEARIZER_H_
+#define V8_COMPILER_EFFECT_CONTROL_LINEARIZER_H_
+
+#include "src/compiler/common-operator.h"
+#include "src/compiler/node.h"
+#include "src/compiler/simplified-operator.h"
+
+namespace v8 {
+namespace internal {
+
+class Zone;
+
+namespace compiler {
+
+class CommonOperatorBuilder;
+class SimplifiedOperatorBuilder;
+class MachineOperatorBuilder;
+class JSGraph;
+class Graph;
+class Schedule;
+
+class EffectControlLinearizer {
+ public:
+  EffectControlLinearizer(JSGraph* graph, Schedule* schedule, Zone* temp_zone);
+
+  void Run();
+
+ private:
+  void ProcessNode(Node* node, Node** current_effect, Node** control);
+
+  struct ValueEffectControl {
+    Node* value;
+    Node* effect;
+    Node* control;
+    ValueEffectControl(Node* value, Node* effect, Node* control)
+        : value(value), effect(effect), control(control) {}
+  };
+
+  bool TryWireInStateEffect(Node* node, Node** effect, Node** control);
+  ValueEffectControl LowerChangeInt32ToTagged(Node* node, Node* effect,
+                                              Node* control);
+  ValueEffectControl LowerChangeUint32ToTagged(Node* node, Node* effect,
+                                               Node* control);
+  ValueEffectControl LowerChangeFloat64ToTagged(Node* node, Node* effect,
+                                                Node* control);
+  ValueEffectControl AllocateHeapNumberWithValue(Node* node, Node* effect,
+                                                 Node* control);
+
+  Node* ChangeInt32ToSmi(Node* value);
+  Node* ChangeUint32ToSmi(Node* value);
+  Node* ChangeInt32ToFloat64(Node* value);
+  Node* ChangeUint32ToFloat64(Node* value);
+
+  Node* HeapNumberValueIndexConstant();
+  Node* SmiMaxValueConstant();
+  Node* SmiShiftBitsConstant();
+
+  JSGraph* jsgraph() const { return js_graph_; }
+  Graph* graph() const;
+  Schedule* schedule() const { return schedule_; }
+  Zone* temp_zone() const { return temp_zone_; }
+  CommonOperatorBuilder* common() const;
+  SimplifiedOperatorBuilder* simplified() const;
+  MachineOperatorBuilder* machine() const;
+
+  JSGraph* js_graph_;
+  Schedule* schedule_;
+  Zone* temp_zone_;
+  SetOncePointer<const Operator> allocate_heap_number_operator_;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_EFFECT_CONTROL_LINEARIZER_H_

src/compiler/graph-reducer.cc

@@ -222,7 +222,11 @@ void GraphReducer::ReplaceWithValue(Node* node, Node* value, Node* effect,
         edge.UpdateTo(dead_);
         Revisit(user);
       } else {
-        UNREACHABLE();
+        DCHECK_NOT_NULL(control);
+        edge.UpdateTo(control);
+        Revisit(user);
+        // TODO(jarin) Check that the node cannot throw (otherwise, it
+        // would have to be connected via IfSuccess/IfException).
       }
     } else if (NodeProperties::IsEffectEdge(edge)) {
       DCHECK_NOT_NULL(effect);

src/compiler/pipeline.cc

@@ -19,6 +19,7 @@
 #include "src/compiler/common-operator-reducer.h"
 #include "src/compiler/control-flow-optimizer.h"
 #include "src/compiler/dead-code-elimination.h"
+#include "src/compiler/effect-control-linearizer.h"
 #include "src/compiler/escape-analysis-reducer.h"
 #include "src/compiler/escape-analysis.h"
 #include "src/compiler/frame-elider.h"
@@ -225,6 +226,7 @@ class PipelineData {
     DCHECK(!schedule_);
     schedule_ = schedule;
   }
+  void reset_schedule() { schedule_ = nullptr; }
 
   Zone* instruction_zone() const { return instruction_zone_; }
   InstructionSequence* sequence() const { return sequence_; }
@@ -503,6 +505,9 @@ PipelineCompilationJob::Status PipelineCompilationJob::CreateGraphImpl() {
   if (!info()->shared_info()->asm_function() || FLAG_turbo_asm_deoptimization) {
     info()->MarkAsDeoptimizationEnabled();
   }
+  if (!info()->shared_info()->asm_function()) {
+    info()->MarkAsEffectSchedulingEnabled();
+  }
 
   if (!info()->shared_info()->HasBytecodeArray()) {
     if (!Compiler::EnsureDeoptimizationSupport(info())) return FAILED;
@@ -799,6 +804,35 @@ struct ControlFlowOptimizationPhase {
   }
 };
 
+struct EffectControlLinearizationPhase {
+  static const char* phase_name() { return "effect linearization"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    // The scheduler requires the graphs to be trimmed, so trim now.
+    // TODO(jarin) Remove the trimming once the scheduler can handle untrimmed
+    // graphs.
+    GraphTrimmer trimmer(temp_zone, data->graph());
+    NodeVector roots(temp_zone);
+    data->jsgraph()->GetCachedNodes(&roots);
+    trimmer.TrimGraph(roots.begin(), roots.end());
+
+    // Schedule the graph without node splitting so that we can
+    // fix the effect and control flow for nodes with low-level side
+    // effects (such as changing representation to tagged or
+    // 'floating' allocation regions.)
+    Schedule* schedule = Scheduler::ComputeSchedule(temp_zone, data->graph(),
+                                                    Scheduler::kNoFlags);
+    if (FLAG_turbo_verify) ScheduleVerifier::Run(schedule);
+
+    // Post-pass for wiring the control/effects
+    // - connect allocating representation changes into the control&effect
+    //   chains and lower them,
+    // - get rid of the region markers,
+    // - introduce effect phis and rewire effects to get SSA again.
+    EffectControlLinearizer introducer(data->jsgraph(), schedule, temp_zone);
+    introducer.Run();
+  }
+};
 
 struct ChangeLoweringPhase {
   static const char* phase_name() { return "change lowering"; }
@@ -823,6 +857,26 @@ struct ChangeLoweringPhase {
   }
 };
 
+struct ComputeEffectSchedulePhase {
+  static const char* phase_name() { return "effect scheduling"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    Schedule* schedule = Scheduler::ComputeSchedule(temp_zone, data->graph(),
+                                                    Scheduler::kNoFlags);
+    if (FLAG_turbo_verify) ScheduleVerifier::Run(schedule);
+    data->set_schedule(schedule);
+  }
+};
+
+struct EffectScheduleTrimmingPhase {
+  static const char* phase_name() { return "effect schedule graph trimming"; }
+  void Run(PipelineData* data, Zone* temp_zone) {
+    GraphTrimmer trimmer(temp_zone, data->graph());
+    NodeVector roots(temp_zone);
+    data->jsgraph()->GetCachedNodes(&roots);
+    trimmer.TrimGraph(roots.begin(), roots.end());
+  }
+};
 
 struct EarlyGraphTrimmingPhase {
   static const char* phase_name() { return "early graph trimming"; }
@@ -1251,6 +1305,12 @@ Handle<Code> Pipeline::GenerateCode() {
   Run<SimplifiedLoweringPhase>();
   RunPrintAndVerify("Lowered simplified");
 
+  if (info()->is_effect_scheduling_enabled()) {
+    // TODO(jarin) Run value numbering for the representation changes.
+    Run<EffectControlLinearizationPhase>();
+    RunPrintAndVerify("Effect and control linearized");
+  }
+
   Run<BranchEliminationPhase>();
   RunPrintAndVerify("Branch conditions eliminated");
 

src/compiler/schedule.cc

@@ -199,11 +199,28 @@ void Schedule::AddGoto(BasicBlock* block, BasicBlock* succ) {
   AddSuccessor(block, succ);
 }
 
+#if DEBUG
+namespace {
+
+bool IsPotentiallyThrowingCall(IrOpcode::Value opcode) {
+  switch (opcode) {
+#define BUILD_BLOCK_JS_CASE(Name) case IrOpcode::k##Name:
+    JS_OP_LIST(BUILD_BLOCK_JS_CASE)
+#undef BUILD_BLOCK_JS_CASE
+    case IrOpcode::kCall:
+      return true;
+    default:
+      return false;
+  }
+}
+
+}  // namespace
+#endif  // DEBUG
 
 void Schedule::AddCall(BasicBlock* block, Node* call, BasicBlock* success_block,
                        BasicBlock* exception_block) {
   DCHECK_EQ(BasicBlock::kNone, block->control());
-  DCHECK_EQ(IrOpcode::kCall, call->opcode());
+  DCHECK(IsPotentiallyThrowingCall(call->opcode()));
   block->set_control(BasicBlock::kCall);
   AddSuccessor(block, success_block);
   AddSuccessor(block, exception_block);

src/compiler/scheduler.cc

@@ -324,6 +324,10 @@ class CFGBuilder : public ZoneObject {
       case IrOpcode::kSwitch:
         BuildBlocksForSuccessors(node);
         break;
+#define BUILD_BLOCK_JS_CASE(Name) case IrOpcode::k##Name:
+        JS_OP_LIST(BUILD_BLOCK_JS_CASE)
+// JS opcodes are just like calls => fall through.
+#undef BUILD_BLOCK_JS_CASE
       case IrOpcode::kCall:
         if (NodeProperties::IsExceptionalCall(node)) {
           BuildBlocksForSuccessors(node);
@@ -364,6 +368,10 @@ class CFGBuilder : public ZoneObject {
         scheduler_->UpdatePlacement(node, Scheduler::kFixed);
         ConnectThrow(node);
         break;
+#define CONNECT_BLOCK_JS_CASE(Name) case IrOpcode::k##Name:
+        JS_OP_LIST(CONNECT_BLOCK_JS_CASE)
+// JS opcodes are just like calls => fall through.
+#undef CONNECT_BLOCK_JS_CASE
       case IrOpcode::kCall:
         if (NodeProperties::IsExceptionalCall(node)) {
           scheduler_->UpdatePlacement(node, Scheduler::kFixed);

test/unittests/compiler/effect-control-linearizer-unittest.cc

+// Copyright 2015 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/effect-control-linearizer.h"
+#include "src/compiler/access-builder.h"
+#include "src/compiler/js-graph.h"
+#include "src/compiler/node-properties.h"
+#include "src/compiler/schedule.h"
+#include "src/compiler/simplified-operator.h"
+#include "test/unittests/compiler/graph-unittest.h"
+#include "test/unittests/compiler/node-test-utils.h"
+#include "test/unittests/test-utils.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+class EffectControlLinearizerTest : public TypedGraphTest {
+ public:
+  EffectControlLinearizerTest()
+      : TypedGraphTest(3),
+        machine_(zone()),
+        javascript_(zone()),
+        simplified_(zone()),
+        jsgraph_(isolate(), graph(), common(), &javascript_, &simplified_,
+                 &machine_) {}
+
+  JSGraph* jsgraph() { return &jsgraph_; }
+  SimplifiedOperatorBuilder* simplified() { return &simplified_; }
+
+ private:
+  MachineOperatorBuilder machine_;
+  JSOperatorBuilder javascript_;
+  SimplifiedOperatorBuilder simplified_;
+  JSGraph jsgraph_;
+};
+
+namespace {
+
+BasicBlock* AddBlockToSchedule(Schedule* schedule) {
+  BasicBlock* block = schedule->NewBasicBlock();
+  block->set_rpo_number(static_cast<int32_t>(schedule->rpo_order()->size()));
+  schedule->rpo_order()->push_back(block);
+  return block;
+}
+
+}  // namespace
+
+TEST_F(EffectControlLinearizerTest, SimpleLoad) {
+  Schedule schedule(zone());
+
+  // Create the graph.
+  Node* heap_number = NumberConstant(0.5);
+  Node* load = graph()->NewNode(
+      simplified()->LoadField(AccessBuilder::ForHeapNumberValue()), heap_number,
+      graph()->start(), graph()->start());
+  Node* ret = graph()->NewNode(common()->Return(), load, graph()->start(),
+                               graph()->start());
+
+  // Build the basic block structure.
+  BasicBlock* start = schedule.start();
+  schedule.rpo_order()->push_back(start);
+  start->set_rpo_number(0);
+
+  // Populate the basic blocks with nodes.
+  schedule.AddNode(start, graph()->start());
+  schedule.AddNode(start, heap_number);
+  schedule.AddNode(start, load);
+  schedule.AddReturn(start, ret);
+
+  // Run the state effect introducer.
+  EffectControlLinearizer introducer(jsgraph(), &schedule, zone());
+  introducer.Run();
+
+  EXPECT_THAT(load,
+              IsLoadField(AccessBuilder::ForHeapNumberValue(), heap_number,
+                          graph()->start(), graph()->start()));
+  // The return should have reconnected effect edge to the load.
+  EXPECT_THAT(ret, IsReturn(load, load, graph()->start()));
+}
+
+TEST_F(EffectControlLinearizerTest, DiamondLoad) {
+  Schedule schedule(zone());
+
+  // Create the graph.
+  Node* branch =
+      graph()->NewNode(common()->Branch(), Int32Constant(0), graph()->start());
+
+  Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+  Node* heap_number = NumberConstant(0.5);
+  Node* vtrue = graph()->NewNode(
+      simplified()->LoadField(AccessBuilder::ForHeapNumberValue()), heap_number,
+      graph()->start(), if_true);
+
+  Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
+  Node* vfalse = Float64Constant(2);
+
+  Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
+  Node* phi = graph()->NewNode(
+      common()->Phi(MachineRepresentation::kFloat64, 2), vtrue, vfalse, merge);
+
+  Node* ret =
+      graph()->NewNode(common()->Return(), phi, graph()->start(), merge);
+
+  // Build the basic block structure.
+  BasicBlock* start = schedule.start();
+  schedule.rpo_order()->push_back(start);
+  start->set_rpo_number(0);
+
+  BasicBlock* tblock = AddBlockToSchedule(&schedule);
+  BasicBlock* fblock = AddBlockToSchedule(&schedule);
+  BasicBlock* mblock = AddBlockToSchedule(&schedule);
+
+  // Populate the basic blocks with nodes.
+  schedule.AddNode(start, graph()->start());
+  schedule.AddBranch(start, branch, tblock, fblock);
+
+  schedule.AddNode(tblock, if_true);
+  schedule.AddNode(tblock, heap_number);
+  schedule.AddNode(tblock, vtrue);
+  schedule.AddGoto(tblock, mblock);
+
+  schedule.AddNode(fblock, if_false);
+  schedule.AddNode(fblock, vfalse);
+  schedule.AddGoto(fblock, mblock);
+
+  schedule.AddNode(mblock, merge);
+  schedule.AddNode(mblock, phi);
+  schedule.AddReturn(mblock, ret);
+
+  // Run the state effect introducer.
+  EffectControlLinearizer introducer(jsgraph(), &schedule, zone());
+  introducer.Run();
+
+  // The effect input to the return should be an effect phi with the
+  // newly introduced effectful change operators.
+  ASSERT_THAT(
+      ret, IsReturn(phi, IsEffectPhi(vtrue, graph()->start(), merge), merge));
+}
+
+TEST_F(EffectControlLinearizerTest, LoopLoad) {
+  Schedule schedule(zone());
+
+  // Create the graph.
+  Node* loop = graph()->NewNode(common()->Loop(1), graph()->start());
+  Node* effect_phi =
+      graph()->NewNode(common()->EffectPhi(1), graph()->start(), loop);
+
+  Node* cond = Int32Constant(0);
+  Node* branch = graph()->NewNode(common()->Branch(), cond, loop);
+
+  Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+
+  Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
+
+  loop->AppendInput(zone(), if_false);
+  NodeProperties::ChangeOp(loop, common()->Loop(2));
+
+  effect_phi->InsertInput(zone(), 1, effect_phi);
+  NodeProperties::ChangeOp(effect_phi, common()->EffectPhi(2));
+
+  Node* heap_number = NumberConstant(0.5);
+  Node* load = graph()->NewNode(
+      simplified()->LoadField(AccessBuilder::ForHeapNumberValue()), heap_number,
+      graph()->start(), loop);
+
+  Node* ret = graph()->NewNode(common()->Return(), load, effect_phi, if_true);
+
+  // Build the basic block structure.
+  BasicBlock* start = schedule.start();
+  schedule.rpo_order()->push_back(start);
+  start->set_rpo_number(0);
+
+  BasicBlock* lblock = AddBlockToSchedule(&schedule);
+  BasicBlock* fblock = AddBlockToSchedule(&schedule);
+  BasicBlock* rblock = AddBlockToSchedule(&schedule);
+
+  // Populate the basic blocks with nodes.
+  schedule.AddNode(start, graph()->start());
+  schedule.AddGoto(start, lblock);
+
+  schedule.AddNode(lblock, loop);
+  schedule.AddNode(lblock, effect_phi);
+  schedule.AddNode(lblock, heap_number);
+  schedule.AddNode(lblock, load);
+  schedule.AddNode(lblock, cond);
+  schedule.AddBranch(lblock, branch, rblock, fblock);
+
+  schedule.AddNode(fblock, if_false);
+  schedule.AddGoto(fblock, lblock);
+
+  schedule.AddNode(rblock, if_true);
+  schedule.AddReturn(rblock, ret);
+
+  // Run the state effect introducer.
+  EffectControlLinearizer introducer(jsgraph(), &schedule, zone());
+  introducer.Run();
+
+  ASSERT_THAT(ret, IsReturn(load, load, if_true));
+  EXPECT_THAT(load, IsLoadField(AccessBuilder::ForHeapNumberValue(),
+                                heap_number, effect_phi, loop));
+}
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8

test/unittests/unittests.gyp

@@ -50,6 +50,7 @@
         'compiler/control-flow-optimizer-unittest.cc',
         'compiler/dead-code-elimination-unittest.cc',
         'compiler/diamond-unittest.cc',
+        'compiler/effect-control-linearizer-unittest.cc',
         'compiler/escape-analysis-unittest.cc',
         'compiler/graph-reducer-unittest.cc',
         'compiler/graph-reducer-unittest.h',

tools/gyp/v8.gyp

@@ -510,6 +510,8 @@
         '../../src/compiler/dead-code-elimination.cc',
         '../../src/compiler/dead-code-elimination.h',
         '../../src/compiler/diamond.h',
+        '../../src/compiler/effect-control-linearizer.cc',
+        '../../src/compiler/effect-control-linearizer.h',
         '../../src/compiler/escape-analysis.cc',
         '../../src/compiler/escape-analysis.h',
         "../../src/compiler/escape-analysis-reducer.cc",