Move backtrace logic to backtrace_helper.h
Refactor this out so we can use it other places.
Test: test/run-test --host --gcstress --dev --64 048
Change-Id: I1c357714badd417a67a34cd5d371ddbf1282a179
diff --git a/runtime/backtrace_helper.h b/runtime/backtrace_helper.h
new file mode 100644
index 0000000..ace118c
--- /dev/null
+++ b/runtime/backtrace_helper.h
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_BACKTRACE_HELPER_H_
+#define ART_RUNTIME_BACKTRACE_HELPER_H_
+
+#include <unwind.h>
+
+namespace art {
+
+// Based on debug malloc logic from libc/bionic/debug_stacktrace.cpp.
+class BacktraceCollector {
+ public:
+ BacktraceCollector(uintptr_t* out_frames, size_t max_depth, size_t skip_count)
+ : out_frames_(out_frames), max_depth_(max_depth), skip_count_(skip_count) {}
+
+ size_t NumFrames() const {
+ return num_frames_;
+ }
+
+ // Collect the backtrace, do not call more than once.
+ void Collect() {
+ _Unwind_Backtrace(&Callback, this);
+ }
+
+ private:
+ static _Unwind_Reason_Code Callback(_Unwind_Context* context, void* arg) {
+ auto* const state = reinterpret_cast<BacktraceCollector*>(arg);
+ const uintptr_t ip = _Unwind_GetIP(context);
+ // The first stack frame is get_backtrace itself. Skip it.
+ if (ip != 0 && state->skip_count_ > 0) {
+ --state->skip_count_;
+ return _URC_NO_REASON;
+ }
+ // ip may be off for ARM but it shouldn't matter since we only use it for hashing.
+ state->out_frames_[state->num_frames_] = ip;
+ state->num_frames_++;
+ return state->num_frames_ >= state->max_depth_ ? _URC_END_OF_STACK : _URC_NO_REASON;
+ }
+
+ uintptr_t* const out_frames_ = nullptr;
+ size_t num_frames_ = 0u;
+ const size_t max_depth_ = 0u;
+ size_t skip_count_ = 0u;
+};
+
+// A bounded sized backtrace.
+template <size_t kMaxFrames>
+class FixedSizeBacktrace {
+ public:
+ void Collect(size_t skip_count) {
+ BacktraceCollector collector(frames_, kMaxFrames, skip_count);
+ collector.Collect();
+ num_frames_ = collector.NumFrames();
+ }
+
+ uint64_t Hash() const {
+ uint64_t hash = 9314237;
+ for (size_t i = 0; i < num_frames_; ++i) {
+ hash = hash * 2654435761 + frames_[i];
+ hash += (hash >> 13) ^ (hash << 6);
+ }
+ return hash;
+ }
+
+ private:
+ uintptr_t frames_[kMaxFrames];
+ size_t num_frames_;
+};
+
+} // namespace art
+
+#endif // ART_RUNTIME_BACKTRACE_HELPER_H_