commit 432981b9055b411c4f4f1c5d6f60c94f8648c0b7
author Christopher Ferris <cferris@google.com> Thu Feb 22 19:42:53 2018 -0800
committer Christopher Ferris <cferris@google.com> Fri Feb 23 09:14:06 2018 -0800
tree fdca6018896e96e0097ae4ad02de9f327af40510
parent cdf778f5d92ab8748897a4d95693524d3273c23a

Modify the offline handling interface.

- Add a new function Backtrace::UnwindOffline that takes the stack data.
- Modify BacktraceMap::CreateOffline so it doesn't take the stack data.
  This makes it easier to reuse the map object created this way.

Reusing the map object increases simpleperf speed (unwinds per second) by 50%.

Test: backtrace_test libunwindstack_test
Change-Id: I90cfbae9e50d95d8a0e3cd394b33ba36d65d45f7

libbacktrace/UnwindStack.cpp

diff --git a/libbacktrace/UnwindStack.cpp b/libbacktrace/UnwindStack.cpp
index 0e32e47..711a12a 100644
--- a/libbacktrace/UnwindStack.cpp
+++ b/libbacktrace/UnwindStack.cpp
@@ -128,6 +128,22 @@
   return true;
 }
 
+bool Backtrace::UnwindOffline(unwindstack::Regs* regs, BacktraceMap* back_map,
+                              const backtrace_stackinfo_t& stack,
+                              std::vector<backtrace_frame_data_t>* frames,
+                              BacktraceUnwindError* error) {
+  UnwindStackOfflineMap* offline_map = reinterpret_cast<UnwindStackOfflineMap*>(back_map);
+  // Create the process memory from the stack data since this will almost
+  // always be different each unwind.
+  if (!offline_map->CreateProcessMemory(stack)) {
+    if (error != nullptr) {
+      error->error_code = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
+    }
+    return false;
+  }
+  return Backtrace::Unwind(regs, back_map, frames, 0U, nullptr, error);
+}
+
 UnwindStackCurrent::UnwindStackCurrent(pid_t pid, pid_t tid, BacktraceMap* map)
     : BacktraceCurrent(pid, tid, map) {}
 
@@ -221,12 +237,12 @@
 Backtrace* Backtrace::CreateOffline(ArchEnum arch, pid_t pid, pid_t tid,
                                     const std::vector<backtrace_map_t>& maps,
                                     const backtrace_stackinfo_t& stack) {
-  BacktraceMap* map = BacktraceMap::CreateOffline(pid, maps, stack);
-  if (map == nullptr) {
+  std::unique_ptr<UnwindStackOfflineMap> map(
+      reinterpret_cast<UnwindStackOfflineMap*>(BacktraceMap::CreateOffline(pid, maps)));
+  if (map.get() == nullptr || !map->CreateProcessMemory(stack)) {
     return nullptr;
   }
-
-  return new UnwindStackOffline(arch, pid, tid, map, false);
+  return new UnwindStackOffline(arch, pid, tid, map.release(), false);
 }
 
 Backtrace* Backtrace::CreateOffline(ArchEnum arch, pid_t pid, pid_t tid, BacktraceMap* map) {