[turbofan] Add --csa-verify flag that enables machine graph verification of code stubs.

src/compiler/pipeline.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/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <memory>
 #include <sstream>
 
@@ skipping 1744 matching lines @@
     RunPrintAndVerify("Late trimmed", true);
   }
   if (data->schedule() == nullptr) Run<ComputeSchedulePhase>();
   TraceSchedule(data->info(), data->schedule());
 
   if (FLAG_turbo_profiling) {
     data->set_profiler_data(BasicBlockInstrumentor::Instrument(
         info(), data->graph(), data->schedule()));
   }
 
-  if (FLAG_turbo_verify_machine_graph != nullptr &&
-      (!strcmp(FLAG_turbo_verify_machine_graph, "*") ||
-       !strcmp(FLAG_turbo_verify_machine_graph,
-               data->info()->GetDebugName().get()))) {
+  bool verify_stub_graph =
+      DEBUG_BOOL && data->info()->IsStub() && (FLAG_csa_verify > 0);
+  // TODO(ishell): Always enable graph verification of stubs in debug mode
+  // once all the issues are fixed.
+  if (verify_stub_graph) {
+    // Enable graph verification for the first |FLAG_csa_verify| stubs.
+    --FLAG_csa_verify;

[Michael Starzinger, 2016/12/05 18:03:36]

suggestion: As discussed offline, this is not safe across multiple isolates
(i.e. the flag is per-process, but the pipeline is only synchronized
per-isolate). Could we copy out the initial value of FLAG_csa_verify into the
{Isolate} when it is initialized and then mutate that value instead (similar to
what we do to Heap::allocation_timeout for example)?

Or alternatively, have one cctest that sets the flag to a non-zero value, so
that we have full control over when this flag is set. We would just not support
to pass this flag via Chrome (or other embedders).

[Igor Sheludko, 2016/12/06 13:57:52]

I added the cctest.

+  }
+
+  if (verify_stub_graph || (FLAG_turbo_verify_machine_graph != nullptr &&
+                            (!strcmp(FLAG_turbo_verify_machine_graph, "*") ||
+                             !strcmp(FLAG_turbo_verify_machine_graph,
+                                     data->info()->GetDebugName().get())))) {
     Zone temp_zone(data->isolate()->allocator(), ZONE_NAME);
     MachineGraphVerifier::Run(data->graph(), data->schedule(), linkage,
                               &temp_zone);
   }
 
   data->InitializeInstructionSequence(call_descriptor);
 
   data->InitializeFrameData(call_descriptor);
   // Select and schedule instructions covering the scheduled graph.
   Run<InstructionSelectionPhase>(linkage);
@@ skipping 190 matching lines @@
   data->DeleteRegisterAllocationZone();
 }
 
 CompilationInfo* PipelineImpl::info() const { return data_->info(); }
 
 Isolate* PipelineImpl::isolate() const { return info()->isolate(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8