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

5 files changed, 39 insertions, 17 deletions

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 @@ bool Backtrace::Unwind(unwindstack::Regs* regs, BacktraceMap* back_map,
   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 @@ bool UnwindStackOffline::ReadWord(uint64_t, word_t*) {
 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) {
diff --git a/libbacktrace/UnwindStackMap.cpp b/libbacktrace/UnwindStackMap.cpp
index 6dcc621..9c6fed4 100644
--- a/libbacktrace/UnwindStackMap.cpp
+++ b/libbacktrace/UnwindStackMap.cpp
@@ -127,12 +127,7 @@ bool UnwindStackOfflineMap::Build() {
   return false;
 }
 
-bool UnwindStackOfflineMap::Build(const std::vector<backtrace_map_t>& backtrace_maps,
-                                  const backtrace_stackinfo_t& stack) {
-  if (stack.start >= stack.end) {
-    return false;
-  }
-
+bool UnwindStackOfflineMap::Build(const std::vector<backtrace_map_t>& backtrace_maps) {
   for (const backtrace_map_t& map : backtrace_maps) {
     maps_.push_back(map);
   }
@@ -145,6 +140,13 @@ bool UnwindStackOfflineMap::Build(const std::vector<backtrace_map_t>& backtrace_
   for (const backtrace_map_t& map : maps_) {
     maps->Add(map.start, map.end, map.offset, map.flags, map.name, map.load_bias);
   }
+  return true;
+}
+
+bool UnwindStackOfflineMap::CreateProcessMemory(const backtrace_stackinfo_t& stack) {
+  if (stack.start >= stack.end) {
+    return false;
+  }
 
   // Create the process memory from the stack data.
   uint64_t size = stack.end - stack.start;
@@ -154,7 +156,6 @@ bool UnwindStackOfflineMap::Build(const std::vector<backtrace_map_t>& backtrace_
   std::shared_ptr<unwindstack::Memory> shared_memory(memory);
 
   process_memory_.reset(new unwindstack::MemoryRange(shared_memory, 0, size, stack.start));
-
   return true;
 }
 
@@ -182,10 +183,9 @@ BacktraceMap* BacktraceMap::Create(pid_t pid, bool uncached) {
 //-------------------------------------------------------------------------
 // BacktraceMap create offline function.
 //-------------------------------------------------------------------------
-BacktraceMap* BacktraceMap::CreateOffline(pid_t pid, const std::vector<backtrace_map_t>& maps,
-                                          const backtrace_stackinfo_t& stack) {
+BacktraceMap* BacktraceMap::CreateOffline(pid_t pid, const std::vector<backtrace_map_t>& maps) {
   UnwindStackOfflineMap* map = new UnwindStackOfflineMap(pid);
-  if (!map->Build(maps, stack)) {
+  if (!map->Build(maps)) {
     delete map;
     return nullptr;
   }
diff --git a/libbacktrace/UnwindStackMap.h b/libbacktrace/UnwindStackMap.h
index 94cbfb2..ec0d9c1 100644
--- a/libbacktrace/UnwindStackMap.h
+++ b/libbacktrace/UnwindStackMap.h
@@ -76,7 +76,9 @@ class UnwindStackOfflineMap : public UnwindStackMap {
 
   bool Build() override;
 
-  bool Build(const std::vector<backtrace_map_t>& maps, const backtrace_stackinfo_t& stack);
+  bool Build(const std::vector<backtrace_map_t>& maps);
+
+  bool CreateProcessMemory(const backtrace_stackinfo_t& stack);
 };
 
 #endif  // _LIBBACKTRACE_UNWINDSTACK_MAP_H
diff --git a/libbacktrace/include/backtrace/Backtrace.h b/libbacktrace/include/backtrace/Backtrace.h
index 7a37015..a088207 100644
--- a/libbacktrace/include/backtrace/Backtrace.h
+++ b/libbacktrace/include/backtrace/Backtrace.h
@@ -151,6 +151,11 @@ class Backtrace {
                      std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames,
                      std::vector<std::string>* skip_names, BacktraceUnwindError* error = nullptr);
 
+  static bool UnwindOffline(unwindstack::Regs* regs, BacktraceMap* back_map,
+                            const backtrace_stackinfo_t& stack_info,
+                            std::vector<backtrace_frame_data_t>* frames,
+                            BacktraceUnwindError* error = nullptr);
+
   // Get the function name and offset into the function given the pc.
   // If the string is empty, then no valid function name was found,
   // or the pc is not in any valid map.
diff --git a/libbacktrace/include/backtrace/BacktraceMap.h b/libbacktrace/include/backtrace/BacktraceMap.h
index da54472..473d195 100644
--- a/libbacktrace/include/backtrace/BacktraceMap.h
+++ b/libbacktrace/include/backtrace/BacktraceMap.h
@@ -64,8 +64,7 @@ public:
   // is unsupported.
   static BacktraceMap* Create(pid_t pid, bool uncached = false);
 
-  static BacktraceMap* CreateOffline(pid_t pid, const std::vector<backtrace_map_t>& maps,
-                                     const backtrace_stackinfo_t& stack);
+  static BacktraceMap* CreateOffline(pid_t pid, const std::vector<backtrace_map_t>& maps);
 
   virtual ~BacktraceMap();