[compiler] Split GenerateCode into AssembleCode and FinalizeCode.

AssembleCode will eventually be moved into ExecuteJob, i.e., off
the main thread.

Bug: v8:6048
Change-Id: If84ee2aaca6c8827cb769c7d69e5094fb4f32e4b
Reviewed-on: https://chromium-review.googlesource.com/506669
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45372}

src/compiler/code-generator.cc

@@ -60,7 +60,8 @@ CodeGenerator::CodeGenerator(Frame* frame, Linkage* linkage,
       osr_pc_offset_(-1),
       optimized_out_literal_id_(-1),
       source_position_table_builder_(code->zone(),
-                                     info->SourcePositionRecordingMode()) {
+                                     info->SourcePositionRecordingMode()),
+      result_(kSuccess) {
   for (int i = 0; i < code->InstructionBlockCount(); ++i) {
     new (&labels_[i]) Label;
   }
@@ -74,8 +75,7 @@ void CodeGenerator::CreateFrameAccessState(Frame* frame) {
   frame_access_state_ = new (code()->zone()) FrameAccessState(frame);
 }
 
-
-Handle<Code> CodeGenerator::GenerateCode() {
+void CodeGenerator::AssembleCode() {
   CompilationInfo* info = this->info();
 
   // Open a frame scope to indicate that there is a frame on the stack.  The
@@ -175,14 +175,13 @@ Handle<Code> CodeGenerator::GenerateCode() {
         }
       }
 
-      CodeGenResult result;
       if (FLAG_enable_embedded_constant_pool && !block->needs_frame()) {
         ConstantPoolUnavailableScope constant_pool_unavailable(masm());
-        result = AssembleBlock(block);
+        result_ = AssembleBlock(block);
       } else {
-        result = AssembleBlock(block);
+        result_ = AssembleBlock(block);
       }
-      if (result != kSuccess) return Handle<Code>();
+      if (result_ != kSuccess) return;
       unwinding_info_writer_.EndInstructionBlock(block);
     }
   }
@@ -228,9 +227,15 @@ Handle<Code> CodeGenerator::GenerateCode() {
   unwinding_info_writer_.Finish(masm()->pc_offset());
 
   safepoints()->Emit(masm(), frame()->GetTotalFrameSlotCount());
+  result_ = kSuccess;
+}
+
+Handle<Code> CodeGenerator::FinalizeCode() {
+  if (result_ != kSuccess) return Handle<Code>();
 
   Handle<Code> result = v8::internal::CodeGenerator::MakeCodeEpilogue(
-      masm(), unwinding_info_writer_.eh_frame_writer(), info, Handle<Object>());
+      masm(), unwinding_info_writer_.eh_frame_writer(), info(),
+      Handle<Object>());
   result->set_is_turbofanned(true);
   result->set_stack_slots(frame()->GetTotalFrameSlotCount());
   result->set_safepoint_table_offset(safepoints()->GetCodeOffset());
@@ -255,7 +260,7 @@ Handle<Code> CodeGenerator::GenerateCode() {
   PopulateDeoptimizationData(result);
 
   // Ensure there is space for lazy deoptimization in the relocation info.
-  if (info->ShouldEnsureSpaceForLazyDeopt()) {
+  if (info()->ShouldEnsureSpaceForLazyDeopt()) {
     Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(result);
   }
 

src/compiler/code-generator.h

@@ -80,8 +80,11 @@ class CodeGenerator final : public GapResolver::Assembler {
   explicit CodeGenerator(Frame* frame, Linkage* linkage,
                          InstructionSequence* code, CompilationInfo* info);
 
-  // Generate native code.
-  Handle<Code> GenerateCode();
+  // Generate native code. After calling AssembleCode, call FinalizeCode to
+  // produce the actual code object. If an error occurs during either phase,
+  // FinalizeCode returns a null handle.
+  void AssembleCode();
+  Handle<Code> FinalizeCode();
 
   InstructionSequence* code() const { return code_; }
   FrameAccessState* frame_access_state() const { return frame_access_state_; }
@@ -317,6 +320,7 @@ class CodeGenerator final : public GapResolver::Assembler {
   int osr_pc_offset_;
   int optimized_out_literal_id_;
   SourcePositionTableBuilder source_position_table_builder_;
+  CodeGenResult result_;
 };
 
 }  // namespace compiler

src/compiler/pipeline.cc

@@ -174,6 +174,8 @@ class PipelineData {
   }
 
   ~PipelineData() {
+    delete code_generator_;  // Must happen before zones are destroyed.
+    code_generator_ = nullptr;
     DeleteRegisterAllocationZone();
     DeleteInstructionZone();
     DeleteGraphZone();
@@ -196,6 +198,8 @@ class PipelineData {
     code_ = code;
   }
 
+  CodeGenerator* code_generator() const { return code_generator_; }
+
   // RawMachineAssembler generally produces graphs which cannot be verified.
   bool MayHaveUnverifiableGraph() const { return outer_zone_ == nullptr; }
 
@@ -314,6 +318,11 @@ class PipelineData {
                                sequence(), debug_name());
   }
 
+  void InitializeCodeGenerator(Linkage* linkage) {
+    DCHECK_NULL(code_generator_);
+    code_generator_ = new CodeGenerator(frame(), linkage, sequence(), info());
+  }
+
   void BeginPhaseKind(const char* phase_kind_name) {
     if (pipeline_statistics() != nullptr) {
       pipeline_statistics()->BeginPhaseKind(phase_kind_name);
@@ -339,6 +348,7 @@ class PipelineData {
   bool verify_graph_ = false;
   bool is_asm_ = false;
   Handle<Code> code_ = Handle<Code>::null();
+  CodeGenerator* code_generator_ = nullptr;
 
   // All objects in the following group of fields are allocated in graph_zone_.
   // They are all set to nullptr when the graph_zone_ is destroyed.
@@ -356,8 +366,7 @@ class PipelineData {
 
   // All objects in the following group of fields are allocated in
   // instruction_zone_.  They are all set to nullptr when the instruction_zone_
-  // is
-  // destroyed.
+  // is destroyed.
   ZoneStats::Scope instruction_zone_scope_;
   Zone* instruction_zone_;
   InstructionSequence* sequence_ = nullptr;
@@ -400,8 +409,11 @@ class PipelineImpl final {
   // Run the concurrent optimization passes.
   bool OptimizeGraph(Linkage* linkage);
 
-  // Perform the actual code generation and return handle to a code object.
-  Handle<Code> GenerateCode(Linkage* linkage);
+  // Run the code assembly pass.
+  void AssembleCode(Linkage* linkage);
+
+  // Run the code finalization pass.
+  Handle<Code> FinalizeCode();
 
   bool ScheduleAndSelectInstructions(Linkage* linkage, bool trim_graph);
   void RunPrintAndVerify(const char* phase, bool untyped = false);
@@ -624,7 +636,8 @@ PipelineCompilationJob::Status PipelineCompilationJob::ExecuteJobImpl() {
 }
 
 PipelineCompilationJob::Status PipelineCompilationJob::FinalizeJobImpl() {
-  Handle<Code> code = pipeline_.GenerateCode(linkage_);
+  pipeline_.AssembleCode(linkage_);
+  Handle<Code> code = pipeline_.FinalizeCode();
   if (code.is_null()) {
     if (info()->bailout_reason() == kNoReason) {
       return AbortOptimization(kCodeGenerationFailed);
@@ -711,7 +724,8 @@ PipelineWasmCompilationJob::ExecuteJobImpl() {
 
 PipelineWasmCompilationJob::Status
 PipelineWasmCompilationJob::FinalizeJobImpl() {
-  pipeline_.GenerateCode(&linkage_);
+  pipeline_.AssembleCode(&linkage_);
+  pipeline_.FinalizeCode();
   return SUCCEEDED;
 }
 
@@ -1448,14 +1462,19 @@ struct JumpThreadingPhase {
   }
 };
 
+struct AssembleCodePhase {
+  static const char* phase_name() { return "assemble code"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    data->code_generator()->AssembleCode();
+  }
+};
 
-struct GenerateCodePhase {
-  static const char* phase_name() { return "generate code"; }
+struct FinalizeCodePhase {
+  static const char* phase_name() { return "finalize code"; }
 
-  void Run(PipelineData* data, Zone* temp_zone, Linkage* linkage) {
-    CodeGenerator generator(data->frame(), linkage, data->sequence(),
-                            data->info());
-    data->set_code(generator.GenerateCode());
+  void Run(PipelineData* data, Zone* temp_zone) {
+    data->set_code(data->code_generator()->FinalizeCode());
   }
 };
 
@@ -1724,7 +1743,8 @@ Handle<Code> Pipeline::GenerateCodeForTesting(CompilationInfo* info) {
 
   if (!pipeline.CreateGraph()) return Handle<Code>::null();
   if (!pipeline.OptimizeGraph(&linkage)) return Handle<Code>::null();
-  return pipeline.GenerateCode(&linkage);
+  pipeline.AssembleCode(&linkage);
+  return pipeline.FinalizeCode();
 }
 
 // static
@@ -1900,13 +1920,16 @@ bool PipelineImpl::ScheduleAndSelectInstructions(Linkage* linkage,
   return true;
 }
 
-Handle<Code> PipelineImpl::GenerateCode(Linkage* linkage) {
+void PipelineImpl::AssembleCode(Linkage* linkage) {
   PipelineData* data = this->data_;
-
   data->BeginPhaseKind("code generation");
+  data->InitializeCodeGenerator(linkage);
+  Run<AssembleCodePhase>();
+}
 
-  // Generate final machine code.
-  Run<GenerateCodePhase>(linkage);
+Handle<Code> PipelineImpl::FinalizeCode() {
+  PipelineData* data = this->data_;
+  Run<FinalizeCodePhase>();
 
   Handle<Code> code = data->code();
   if (data->profiler_data()) {
@@ -1954,7 +1977,8 @@ Handle<Code> PipelineImpl::ScheduleAndGenerateCode(
   if (!ScheduleAndSelectInstructions(&linkage, false)) return Handle<Code>();
 
   // Generate the final machine code.
-  return GenerateCode(&linkage);
+  AssembleCode(&linkage);
+  return FinalizeCode();
 }
 
 void PipelineImpl::AllocateRegisters(const RegisterConfiguration* config,