[compiler-rt] [rtsan] Only print out unique stack traces (PR #110028)

[Chris Apple via llvm-commits]

================
@@ -49,7 +50,21 @@ static auto OnViolationAction(DiagnosticsInfo info) {
   return [info]() {
     IncrementTotalErrorCount();
 
-    PrintDiagnostics(info);
+    BufferedStackTrace stack;
+    stack.Unwind(info.pc, info.bp, nullptr,
+                 /*request_fast*/ true);
+
+    StackDepotHandle handle = StackDepotPut_WithHandle(stack);
+
+    const bool is_stack_novel = handle.use_count() == 0;
+    if (UNLIKELY(is_stack_novel)) {
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cjappl wrote:

UNLIKELY because I think in real-time operation we will very likely get into a "steady state" where the stacks are highly duplicated. 

https://github.com/llvm/llvm-project/pull/110028