[compiler] Move tracing from backends to compiler.

src/compiler.cc

 // Copyright 2012 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.h"
 
 #include <algorithm>
 
 #include "src/ast/ast-numbering.h"
 #include "src/ast/prettyprinter.h"
@@ skipping 336 matching lines @@
       return SetLastStatus(FAILED);
     }
     if (FLAG_hydrogen_stats) {
       isolate()->GetHStatistics()->IncrementFullCodeGen(timer.Elapsed());
     }
   }
 
   DCHECK(info()->shared_info()->has_deoptimization_support());
   DCHECK(!info()->is_first_compile());
 
+  if (FLAG_trace_opt) {
+    OFStream os(stdout);
+    os << "[compiling method " << Brief(*info()->closure()) << " using "
+       << compiler_name_;
+    if (info()->is_osr()) os << " OSR";
+    os << "]" << std::endl;
+  }
+
   // Delegate to the underlying implementation.
   DCHECK_EQ(SUCCEEDED, last_status());
   ScopedTimer t(&time_taken_to_create_graph_);
   return SetLastStatus(CreateGraphImpl());
 }
 
 
 OptimizedCompileJob::Status OptimizedCompileJob::OptimizeGraph() {
   DisallowHeapAllocation no_allocation;
   DisallowHandleAllocation no_handles;
@@ skipping 1366 matching lines @@
     MaybeHandle<Code> code;
     if (cached.code != nullptr) code = handle(cached.code);
     Handle<Context> native_context(function->context()->native_context());
     SharedFunctionInfo::AddToOptimizedCodeMap(shared, native_context, code,
                                               literals, BailoutId::None());
   }
 }
 
 }  // namespace internal
 }  // namespace v8