Don't consider --profile-vm when collecting allocation samples; introduce a separate --profile-vm-al

runtime/vm/profiler.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/address_sanitizer.h"
 #include "platform/memory_sanitizer.h"
 #include "platform/utils.h"
 
 #include "vm/allocation.h"
 #include "vm/atomic.h"
@@ skipping 34 matching lines @@
 #endif
 DEFINE_FLAG(int,
             max_profile_depth,
             kSampleSize* kMaxSamplesPerTick,
             "Maximum number stack frames walked. Minimum 1. Maximum 255.");
 #if defined(USING_SIMULATOR)
 DEFINE_FLAG(bool, profile_vm, true, "Always collect native stack traces.");
 #else
 DEFINE_FLAG(bool, profile_vm, false, "Always collect native stack traces.");
 #endif
+DEFINE_FLAG(bool,
+            profile_vm_allocation,
+            false,
+            "Collect native stack traces when tracing Dart allocations.");
 
 #ifndef PRODUCT
 
 bool Profiler::initialized_ = false;
 SampleBuffer* Profiler::sample_buffer_ = NULL;
 AllocationSampleBuffer* Profiler::allocation_sample_buffer_ = NULL;
 ProfilerCounters Profiler::counters_;
 
 void Profiler::InitOnce() {
   // Place some sane restrictions on user controlled flags.
@@ skipping 1110 matching lines @@
 
   if (!GetAndValidateThreadStackBounds(thread, fp, sp, &stack_lower,
                                        &stack_upper)) {
     // Could not get stack boundary.
     return;
   }
 
   Sample* sample = SetupSample(thread, sample_buffer, os_thread->trace_id());
   sample->SetAllocationCid(cid);
 
-  if (FLAG_profile_vm) {
+  if (FLAG_profile_vm_allocation) {
     ProfilerNativeStackWalker native_stack_walker(
         (isolate != NULL) ? isolate->main_port() : ILLEGAL_PORT, sample,
         sample_buffer, stack_lower, stack_upper, pc, fp, sp);
     native_stack_walker.walk();
   } else if (exited_dart_code) {
     ProfilerDartStackWalker dart_exit_stack_walker(
         thread, sample, sample_buffer, stack_lower, stack_upper, pc, fp, sp,
         exited_dart_code, true);
     dart_exit_stack_walker.walk();
   } else {
@@ skipping 525 matching lines @@
 
 
 ProcessedSampleBuffer::ProcessedSampleBuffer()
     : code_lookup_table_(new CodeLookupTable(Thread::Current())) {
   ASSERT(code_lookup_table_ != NULL);
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart