vendor/compiler-rt/compiler-rt-trunk-r290819

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/esan/esan.cpp b/lib/esan/esan.cpp
index 2fb77894d4fb..09b530b6645f 100644
--- a/lib/esan/esan.cpp
+++ b/lib/esan/esan.cpp
@@ -141,9 +141,17 @@ static bool verifyShadowScheme() {
 }
 #endif
 
+uptr VmaSize;
+
 static void initializeShadow() {
   verifyAddressSpace();
 
+  // This is based on the assumption that the intial stack is always allocated
+  // in the topmost segment of the user address space and the assumption
+  // holds true on all the platforms currently supported.
+  VmaSize =
+    (MostSignificantSetBitIndex(GET_CURRENT_FRAME()) + 1);
+
   DCHECK(verifyShadowScheme());
 
   Mapping.initialize(ShadowScale[__esan_which_tool]);