[msan] Chained origins re-design.

Generalize StackDepot and create a new specialized instance of it to
efficiently (i.e. without duplicating stack trace data) store the
origin history tree.

This reduces memory usage for chained origins roughly by an order of
magnitude.

Most importantly, this new design allows us to put two limits on
stored history data (exposed in MSAN_OPTIONS) that help avoid
exponential growth in used memory on certain workloads.

See comments in lib/msan/msan_origin.h for more details.



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@209284 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 6 deletions

diff --git a/lib/msan/msan_allocator.cc b/lib/msan/msan_allocator.cc
index 90b9b31fb..e6da9c14b 100644
--- a/lib/msan/msan_allocator.cc
+++ b/lib/msan/msan_allocator.cc
@@ -16,6 +16,8 @@
 #include "sanitizer_common/sanitizer_stackdepot.h"
 #include "msan.h"
 #include "msan_allocator.h"
+#include "msan_chained_origin_depot.h"
+#include "msan_origin.h"
 #include "msan_thread.h"
 
 namespace __msan {
@@ -101,9 +103,9 @@ static void *MsanAllocate(StackTrace *stack, uptr size, uptr alignment,
     if (__msan_get_track_origins()) {
       u32 stack_id = StackDepotPut(stack->trace, stack->size);
       CHECK(stack_id);
-      CHECK_EQ((stack_id >> 31),
-               0);  // Higher bit is occupied by stack origins.
-      __msan_set_origin(allocated, size, stack_id);
+      u32 id;
+      ChainedOriginDepotPut(stack_id, Origin::kHeapRoot, &id);
+      __msan_set_origin(allocated, size, Origin(id, 1).raw_id());
     }
   }
   MSAN_MALLOC_HOOK(allocated, size);
@@ -124,9 +126,9 @@ void MsanDeallocate(StackTrace *stack, void *p) {
     if (__msan_get_track_origins()) {
       u32 stack_id = StackDepotPut(stack->trace, stack->size);
       CHECK(stack_id);
-      CHECK_EQ((stack_id >> 31),
-               0);  // Higher bit is occupied by stack origins.
-      __msan_set_origin(p, size, stack_id);
+      u32 id;
+      ChainedOriginDepotPut(stack_id, Origin::kHeapRoot, &id);
+      __msan_set_origin(p, size,  Origin(id, 1).raw_id());
     }
   }
   MsanThread *t = GetCurrentThread();