[turbofan] Fix variable liveness control structure creation.

src/compiler/ast-graph-builder.cc

 // 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/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 581 matching lines @@
     Node* return_value = jsgraph()->UndefinedConstant();
     NewNode(javascript()->CallRuntime(Runtime::kTraceExit, 1), return_value);
   }
 
   // Return 'undefined' in case we can fall off the end.
   BuildReturn(jsgraph()->UndefinedConstant());
 }
 
 
 void AstGraphBuilder::ClearNonLiveSlotsInFrameStates() {
-  if (!FLAG_analyze_environment_liveness) return;
+  if (!FLAG_analyze_environment_liveness ||
+      !info()->is_deoptimization_enabled()) {
+    return;
+  }
 
   NonLiveFrameStateSlotReplacer replacer(
       &state_values_cache_, jsgraph()->UndefinedConstant(),
       liveness_analyzer()->local_count(), local_zone());
   Variable* arguments = info()->scope()->arguments();
   if (arguments != nullptr && arguments->IsStackAllocated()) {
     replacer.MarkPermanentlyLive(arguments->index());
   }
   liveness_analyzer()->Run(&replacer);
   if (FLAG_trace_environment_liveness) {
@@ skipping 40 matching lines @@
   return nullptr;
 }
 
 
 AstGraphBuilder::Environment::Environment(AstGraphBuilder* builder,
                                           Scope* scope,
                                           Node* control_dependency)
     : builder_(builder),
       parameters_count_(scope->num_parameters() + 1),
       locals_count_(scope->num_stack_slots()),
-      liveness_block_(builder_->liveness_analyzer()->NewBlock()),
+      liveness_block_(IsLivenessAnalysisEnabled()
+                          ? builder_->liveness_analyzer()->NewBlock()
+                          : nullptr),
       values_(builder_->local_zone()),
       contexts_(builder_->local_zone()),
       control_dependency_(control_dependency),
       effect_dependency_(control_dependency),
       parameters_node_(nullptr),
       locals_node_(nullptr),
       stack_node_(nullptr) {
   DCHECK_EQ(scope->num_parameters() + 1, parameters_count());
 
   // Bind the receiver variable.
@@ skipping 15 matching lines @@
                                   builder->graph()->start());
     values()->push_back(parameter);
   }
 
   // Bind all local variables to undefined.
   Node* undefined_constant = builder->jsgraph()->UndefinedConstant();
   values()->insert(values()->end(), locals_count(), undefined_constant);
 }
 
 
-AstGraphBuilder::Environment::Environment(AstGraphBuilder::Environment* copy)
+AstGraphBuilder::Environment::Environment(AstGraphBuilder::Environment* copy,
+                                          LivenessAnalyzerBlock* liveness_block)
     : builder_(copy->builder_),
       parameters_count_(copy->parameters_count_),
       locals_count_(copy->locals_count_),
+      liveness_block_(liveness_block),
       values_(copy->zone()),
       contexts_(copy->zone()),
       control_dependency_(copy->control_dependency_),
       effect_dependency_(copy->effect_dependency_),
       parameters_node_(copy->parameters_node_),
       locals_node_(copy->locals_node_),
       stack_node_(copy->stack_node_) {
   const size_t kStackEstimate = 7;  // optimum from experimentation!
   values_.reserve(copy->values_.size() + kStackEstimate);
   values_.insert(values_.begin(), copy->values_.begin(), copy->values_.end());
   contexts_.reserve(copy->contexts_.size());
   contexts_.insert(contexts_.begin(), copy->contexts_.begin(),
                    copy->contexts_.end());
-
-  if (FLAG_analyze_environment_liveness) {
-    // Split the liveness blocks.
-    copy->liveness_block_ =
-        builder_->liveness_analyzer()->NewBlock(copy->liveness_block());
-    liveness_block_ =
-        builder_->liveness_analyzer()->NewBlock(copy->liveness_block());
-  }
 }
 
 
 void AstGraphBuilder::Environment::Bind(Variable* variable, Node* node) {
   DCHECK(variable->IsStackAllocated());
   if (variable->IsParameter()) {
     // The parameter indices are shifted by 1 (receiver is parameter
     // index -1 but environment index 0).
     values()->at(variable->index() + 1) = node;
   } else {
     DCHECK(variable->IsStackLocal());
     values()->at(variable->index() + parameters_count_) = node;
-    if (FLAG_analyze_environment_liveness) {
+
+    DCHECK(IsLivenessBlockConsistent());
+    if (liveness_block() != nullptr) {
       liveness_block()->Bind(variable->index());
     }
   }
 }
 
 
 Node* AstGraphBuilder::Environment::Lookup(Variable* variable) {
   DCHECK(variable->IsStackAllocated());
   if (variable->IsParameter()) {
     // The parameter indices are shifted by 1 (receiver is parameter
     // index -1 but environment index 0).
     return values()->at(variable->index() + 1);
   } else {
     DCHECK(variable->IsStackLocal());
-    if (FLAG_analyze_environment_liveness) {
+    DCHECK(IsLivenessBlockConsistent());
+    if (liveness_block() != nullptr) {
       liveness_block()->Lookup(variable->index());
     }
     return values()->at(variable->index() + parameters_count_);
   }
 }
 
 
 void AstGraphBuilder::Environment::MarkAllLocalsLive() {
-  if (FLAG_analyze_environment_liveness) {
+  DCHECK(IsLivenessBlockConsistent());
+  if (liveness_block() != nullptr) {
     for (int i = 0; i < locals_count_; i++) {
       liveness_block()->Lookup(i);
     }
   }
 }
 
 
 AstGraphBuilder::Environment*
+AstGraphBuilder::Environment::CopyForConditional() {
+  LivenessAnalyzerBlock* copy_liveness_block = nullptr;
+  if (liveness_block() != nullptr) {
+    copy_liveness_block =
+        builder_->liveness_analyzer()->NewBlock(liveness_block());
+    liveness_block_ = builder_->liveness_analyzer()->NewBlock(liveness_block());
+  }
+  return new (zone()) Environment(this, copy_liveness_block);
+}
+
+
+AstGraphBuilder::Environment*
+AstGraphBuilder::Environment::CopyAsUnreachable() {
+  Environment* env = new (zone()) Environment(this, nullptr);
+  env->MarkAsUnreachable();
+  return env;
+}
+
+
+AstGraphBuilder::Environment*
 AstGraphBuilder::Environment::CopyAndShareLiveness() {
-  Environment* env = new (zone()) Environment(this);
-  if (FLAG_analyze_environment_liveness) {
-    env->liveness_block_ = liveness_block();
+  if (liveness_block() != nullptr) {
+    // Finish the current liveness block before copying.
+    liveness_block_ = builder_->liveness_analyzer()->NewBlock(liveness_block());
   }
+  Environment* env = new (zone()) Environment(this, liveness_block());
   return env;
 }
 
 
+AstGraphBuilder::Environment* AstGraphBuilder::Environment::CopyForLoop(
+    BitVector* assigned, bool is_osr) {
+  PrepareForLoop(assigned, is_osr);
+  return CopyAndShareLiveness();
+}
+
+
 void AstGraphBuilder::Environment::UpdateStateValues(Node** state_values,
                                                      int offset, int count) {
   bool should_update = false;
   Node** env_values = (count == 0) ? nullptr : &values()->at(offset);
   if (*state_values == NULL || (*state_values)->InputCount() != count) {
     should_update = true;
   } else {
     DCHECK(static_cast<size_t>(offset + count) <= values()->size());
     for (int i = 0; i < count; i++) {
       if ((*state_values)->InputAt(i) != env_values[i]) {
@@ skipping 27 matching lines @@
   UpdateStateValuesWithCache(&locals_node_, parameters_count(), locals_count());
   UpdateStateValues(&stack_node_, parameters_count() + locals_count(),
                     stack_height());
 
   const Operator* op = common()->FrameState(JS_FRAME, ast_id, combine);
 
   Node* result = graph()->NewNode(op, parameters_node_, locals_node_,
                                   stack_node_, builder()->current_context(),
                                   builder()->GetFunctionClosure(),
                                   builder()->jsgraph()->UndefinedConstant());
-  if (FLAG_analyze_environment_liveness) {
+
+  DCHECK(IsLivenessBlockConsistent());
+  if (liveness_block() != nullptr) {
     liveness_block()->Checkpoint(result);
   }
   return result;
 }
 
 
+bool AstGraphBuilder::Environment::IsLivenessAnalysisEnabled() {
+  return FLAG_analyze_environment_liveness &&
+         builder()->info()->is_deoptimization_enabled();
+}
+
+
+bool AstGraphBuilder::Environment::IsLivenessBlockConsistent() {
+  return (!IsLivenessAnalysisEnabled() || IsMarkedAsUnreachable()) ==
+         (liveness_block() == nullptr);
+}
+
+
 AstGraphBuilder::AstContext::AstContext(AstGraphBuilder* own,
                                         Expression::Context kind)
     : kind_(kind), owner_(own), outer_(own->ast_context()) {
   owner()->set_ast_context(this);  // Push.
 #ifdef DEBUG
   original_height_ = environment()->stack_height();
 #endif
 }
 
 
@@ skipping 2615 matching lines @@
     if (has_effect) {
       environment_->UpdateEffectDependency(result);
     }
     if (!environment()->IsMarkedAsUnreachable()) {
       // Update the current control dependency for control-producing nodes.
       if (NodeProperties::IsControl(result)) {
         environment_->UpdateControlDependency(result);
       }
       // Add implicit exception continuation for throwing nodes.
       if (!result->op()->HasProperty(Operator::kNoThrow) && inside_try_scope) {
+        // Copy the environment for the success continuation.
+        Environment* success_env = environment()->CopyForConditional();
+
         Node* on_exception = graph()->NewNode(common()->IfException(), result);
         environment_->UpdateControlDependency(on_exception);
         execution_control()->ThrowValue(on_exception);
+        set_environment(success_env);
       }
       // Add implicit success continuation for throwing nodes.
       if (!result->op()->HasProperty(Operator::kNoThrow)) {
         Node* on_success = graph()->NewNode(common()->IfSuccess(), result);
         environment_->UpdateControlDependency(on_success);
       }
     }
   }
 
   return result;
@@ skipping 15 matching lines @@
   DCHECK(contexts_.size() == other->contexts_.size());
 
   // Nothing to do if the other environment is dead.
   if (other->IsMarkedAsUnreachable()) return;
 
   // Resurrect a dead environment by copying the contents of the other one and
   // placing a singleton merge as the new control dependency.
   if (this->IsMarkedAsUnreachable()) {
     Node* other_control = other->control_dependency_;
     Node* inputs[] = {other_control};
-    liveness_block_ = other->liveness_block_;
     control_dependency_ =
         graph()->NewNode(common()->Merge(1), arraysize(inputs), inputs, true);
     effect_dependency_ = other->effect_dependency_;
     values_ = other->values_;
     contexts_ = other->contexts_;
+    if (IsLivenessAnalysisEnabled()) {
+      liveness_block_ =
+          builder_->liveness_analyzer()->NewBlock(other->liveness_block());
+    }
     return;
   }
 
   // Record the merge for the local variable liveness calculation.
-  // Unfortunately, we have to mirror the logic in the MergeControl method:
-  // connect before merge or loop, or create a new merge otherwise.
-  if (FLAG_analyze_environment_liveness) {
-    if (GetControlDependency()->opcode() != IrOpcode::kLoop &&
-        GetControlDependency()->opcode() != IrOpcode::kMerge) {
+  // For loops, we are connecting a back edge into the existing block;
+  // for merges, we create a new merged block.
+  if (IsLivenessAnalysisEnabled()) {
+    if (GetControlDependency()->opcode() != IrOpcode::kLoop) {
       liveness_block_ =
           builder_->liveness_analyzer()->NewBlock(liveness_block());
     }
     liveness_block()->AddPredecessor(other->liveness_block());
   }
 
   // Create a merge of the control dependencies of both environments and update
   // the current environment's control dependency accordingly.
   Node* control = builder_->MergeControl(this->GetControlDependency(),
                                          other->GetControlDependency());
@@ skipping 156 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8