[DeviceSanitizer] Only try to get backtrace symbols when needed (#2128)

Author: zhaomaosu

source/loader/layers/sanitizer/common.hpp

@@ -127,6 +127,7 @@ inline uint64_t GetSizeAndRedzoneSizeForLocal(uint64_t Size,
             return Result;                                                     \
     }
 
+using BacktraceFrame = void *;
 using BacktraceInfo = std::string;
 
 struct SourceInfo {

source/loader/layers/sanitizer/linux/backtrace.cpp

@@ -15,22 +15,22 @@
 namespace ur_sanitizer_layer {
 
 StackTrace GetCurrentBacktrace() {
-    void *Frames[MAX_BACKTRACE_FRAMES];
+    BacktraceFrame Frames[MAX_BACKTRACE_FRAMES];
     int FrameCount = backtrace(Frames, MAX_BACKTRACE_FRAMES);
-    char **Symbols = backtrace_symbols(Frames, FrameCount);
-
-    if (Symbols == nullptr) {
-        return StackTrace();
-    }
 
     StackTrace Stack;
-    for (int i = 0; i < FrameCount; i++) {
-        BacktraceInfo addr_info(Symbols[i]);
-        Stack.stack.emplace_back(addr_info);
-    }
-    free(Symbols);
+    Stack.stack =
+        std::vector<BacktraceFrame>(&Frames[0], &Frames[FrameCount - 1]);
 
     return Stack;
 }
 
+char **GetBacktraceSymbols(const std::vector<BacktraceFrame> &BacktraceFrames) {
+    assert(!BacktraceFrames.empty());
+
+    char **BacktraceSymbols =
+        backtrace_symbols(&BacktraceFrames[0], BacktraceFrames.size());
+    return BacktraceSymbols;
+}
+
 } // namespace ur_sanitizer_layer

source/loader/layers/sanitizer/stacktrace.cpp

@@ -86,7 +86,11 @@ void StackTrace::print() const {
 
     unsigned index = 0;
 
-    for (auto &BI : stack) {
+    char **BacktraceSymbols = GetBacktraceSymbols(stack);
+
+    for (size_t i = 0; i < stack.size(); i++) {
+        BacktraceInfo BI = BacktraceSymbols[i];
+
         // Skip runtime modules
         if (Contains(BI, "libsycl.so") ||
             Contains(BI, "libpi_unified_runtime.so") ||
@@ -123,6 +127,8 @@ void StackTrace::print() const {
         ++index;
     }
     getContext()->logger.always("");
+
+    free(BacktraceSymbols);
 }
 
 } // namespace ur_sanitizer_layer

source/loader/layers/sanitizer/stacktrace.hpp

@@ -21,11 +21,13 @@ namespace ur_sanitizer_layer {
 constexpr size_t MAX_BACKTRACE_FRAMES = 64;
 
 struct StackTrace {
-    std::vector<BacktraceInfo> stack;
+    std::vector<BacktraceFrame> stack;
 
     void print() const;
 };
 
 StackTrace GetCurrentBacktrace();
 
+char **GetBacktraceSymbols(const std::vector<BacktraceFrame> &BacktraceFrames);
+
 } // namespace ur_sanitizer_layer