Fix processing profiler samples in the presence of Thumb code.

runtime/vm/profiler_service.cc

Index: runtime/vm/profiler_service.cc
diff --git a/runtime/vm/profiler_service.cc b/runtime/vm/profiler_service.cc
index 4e371794ca55f50128f9d594f34be0c78b54fef5..049a1980cd6d63b2dab93b98d23a5649c799af8d 100644
--- a/runtime/vm/profiler_service.cc
+++ b/runtime/vm/profiler_service.cc
@@ -1905,6 +1905,15 @@ class ProfileBuilder : public ValueObject {
                             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,
@@ -1913,7 +1922,7 @@ class ProfileBuilder : public ValueObject {
                        0,
                        code);
     profile_code->SetName(native_name);
-    free(native_name);
+    NativeSymbolResolver::FreeSymbolName(native_name);
     return profile_code;
   }