[sanitizer] Add a fast version of StackDepotGet() for use in LSan.

Add a class that holds a snapshot of the StackDepot optimized for querying by
ID. This allows us to speed up LSan dramatically.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@189217 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_stackdepot.h b/lib/sanitizer_common/sanitizer_stackdepot.h
index 5915fdbb4..8fd0cae72 100644
--- a/lib/sanitizer_common/sanitizer_stackdepot.h
+++ b/lib/sanitizer_common/sanitizer_stackdepot.h
@@ -13,6 +13,7 @@
 #ifndef SANITIZER_STACKDEPOT_H
 #define SANITIZER_STACKDEPOT_H
 
+#include "sanitizer_common.h"
 #include "sanitizer_internal_defs.h"
 
 namespace __sanitizer {
@@ -31,6 +32,31 @@ struct StackDepotStats {
 
 StackDepotStats *StackDepotGetStats();
 
+struct StackDesc;
+
+// Instantiating this class creates a snapshot of StackDepot which can be
+// efficiently queried with StackDepotGet(). You can use it concurrently with
+// StackDepot, but the snapshot is only guaranteed to contain those stack traces
+// which were stored before it was instantiated.
+class StackDepotReverseMap {
+ public:
+  StackDepotReverseMap();
+  const uptr *Get(u32 id, uptr *size);
+
+ private:
+  struct IdDescPair {
+   u32 id;
+   StackDesc *desc;
+
+   static bool IdComparator(const IdDescPair &a, const IdDescPair &b);
+  };
+
+  InternalMmapVector<IdDescPair> map_;
+
+  // Disallow evil constructors.
+  StackDepotReverseMap(const StackDepotReverseMap&);
+  void operator=(const StackDepotReverseMap&);
+};
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_STACKDEPOT_H