[msan] Change the way origin ids are built.

Previously, all origin ids were "chained" origins, i.e values of
ChainedOriginDepot. This added a level of indirection for simple
stack and heap allocation, which were represented as chains of
length 1. This costs both RAM and CPU, but provides a joined 2**29
origin id space. It also made function (any instrumented function)
entry non-async-signal-safe, but that does not really matter because
memory stores in track-origins=2 mode are not async-signal-safe anyway.

With this change, the type of the origin is encoded in origin id.
See comment in msan_origin.h for more details. This reduces chained and stack
origin id range to 2**28 each, but leaves extra 2**31 for heap origins.

This change should not have any user-visible effects.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@223233 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 30 deletions

diff --git a/lib/msan/msan.cc b/lib/msan/msan.cc
index 523bf9465..af42176c2 100644
--- a/lib/msan/msan.cc
+++ b/lib/msan/msan.cc
@@ -205,10 +205,10 @@ void PrintWarningWithOrigin(uptr pc, uptr bp, u32 origin) {
   GET_FATAL_STACK_TRACE_PC_BP(pc, bp);
 
   u32 report_origin =
-    (__msan_get_track_origins() && Origin(origin).isValid()) ? origin : 0;
+    (__msan_get_track_origins() && Origin::isValidId(origin)) ? origin : 0;
   ReportUMR(&stack, report_origin);
 
-  if (__msan_get_track_origins() && !Origin(origin).isValid()) {
+  if (__msan_get_track_origins() && !Origin::isValidId(origin)) {
     Printf(
         "  ORIGIN: invalid (%x). Might be a bug in MemorySanitizer origin "
         "tracking.\n    This could still be a bug in your code, too!\n",
@@ -258,32 +258,9 @@ u32 ChainOrigin(u32 id, StackTrace *stack) {
   if (t && t->InSignalHandler())
     return id;
 
-  Origin o(id);
-  int depth = o.depth();
-  // 0 means unlimited depth.
-  if (flags()->origin_history_size > 0 && depth > 0) {
-    if (depth >= flags()->origin_history_size) {
-      return id;
-    } else {
-      ++depth;
-    }
-  }
-
-  StackDepotHandle h = StackDepotPut_WithHandle(*stack);
-  if (!h.valid()) return id;
-
-  if (flags()->origin_history_per_stack_limit > 0) {
-    int use_count = h.use_count();
-    if (use_count > flags()->origin_history_per_stack_limit) return id;
-  }
-
-  u32 chained_id;
-  bool inserted = ChainedOriginDepotPut(h.id(), o.id(), &chained_id);
-
-  if (inserted && flags()->origin_history_per_stack_limit > 0)
-    h.inc_use_count_unsafe();
-
-  return Origin(chained_id, depth).raw_id();
+  Origin o = Origin::FromRawId(id);
+  Origin chained = Origin::CreateChainedOrigin(o, stack);
+  return chained.raw_id();
 }
 
 }  // namespace __msan
@@ -542,14 +519,14 @@ void __msan_set_alloca_origin4(void *a, uptr size, char *descr, uptr pc) {
     CHECK_LT(idx, kNumStackOriginDescrs);
     StackOriginDescr[idx] = descr + 4;
     StackOriginPC[idx] = pc;
-    ChainedOriginDepotPut(idx, Origin::kStackRoot, &id);
+    id = Origin::CreateStackOrigin(idx).raw_id();
     *id_ptr = id;
     if (print)
       Printf("First time: idx=%d id=%d %s %p \n", idx, id, descr + 4, pc);
   }
   if (print)
     Printf("__msan_set_alloca_origin: descr=%s id=%x\n", descr + 4, id);
-  __msan_set_origin(a, size, Origin(id, 1).raw_id());
+  __msan_set_origin(a, size, id);
 }
 
 u32 __msan_chain_origin(u32 id) {