Fix processing profiler samples in the presence of Thumb code.

runtime/vm/profiler_service.cc

 // Copyright (c) 2015, 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 "vm/profiler_service.h"
 
 #include "vm/growable_array.h"
 #include "vm/native_symbol.h"
 #include "vm/object.h"
 #include "vm/os.h"
@@ skipping 1887 matching lines @@
     char* native_name = NativeSymbolResolver::LookupSymbolName(pc,
                                                                &native_start);
     if (native_name == NULL) {
       // No native name found.
       return new ProfileCode(ProfileCode::kNativeCode,
                             pc,
                             pc + 1,
                             0,
                             code);
     }
+
+#if defined(HOST_ARCH_ARM)

[zra, 2015/10/30 18:28:31]

We should probably check that __thumb__ or __thumb2__ is defined so that
something will still go wrong when the VM is not compiled to thumb code.

[rmacnak, 2015/10/30 18:36:50]

Other compilation units or dynamic libraries in our process might still have
thumb code.

+    if ((native_start % 2) == 1) {

[zra, 2015/10/30 18:28:30]

unconditionally:
const uintptr_t one = 1;
native_start &= ~one;

[rmacnak, 2015/10/30 18:36:50]

Done.

[Florian Schneider, 2015/10/30 19:12:02]

I'd 1U for unsigned literal one. Here however, signed-ness does not matter ( &
and ~). So my guess is that '&= ~1' should just work as expected.

[rmacnak, 2015/10/30 19:48:51]

ack

+      // The symbol for a Thumb function will be xxx1, but we may have samples
+      // at function entry which will have pc xxx0.
+      native_start -= 1;
+    }
+#endif
+
     ASSERT(pc >= native_start);
     ProfileCode* profile_code =
         new ProfileCode(ProfileCode::kNativeCode,
                        native_start,
                        pc + 1,
                        0,
                        code);
     profile_code->SetName(native_name);
-    free(native_name);
+    NativeSymbolResolver::FreeSymbolName(native_name);
     return profile_code;
   }
 
   ProfileCode* RegisterProfileCode(uword pc, int64_t timestamp) {
     ProfileCodeTable* live_table = profile_->live_code_;
     ProfileCodeTable* dead_table = profile_->dead_code_;
 
     ProfileCode* code = live_table->FindCodeForPC(pc);
     if (code == NULL) {
       // Code not found.
@@ skipping 375 matching lines @@
   ASSERT(sample_buffer != NULL);
 
   ClearProfileVisitor clear_profile(isolate);
   sample_buffer->VisitSamples(&clear_profile);
 
   // Enable profile interrupts.
   Profiler::BeginExecution(isolate);
 }
 
 }  // namespace dart