[asan] Pacify ASan reports for TickSample::Init

The code reads whatever the stack pointer points at, and only
later decides whether to use that value for anything.

Change-Id: I9930cb046c4fcb3ba0c931058a9c3dd75df482f0
Reviewed-on: https://chromium-review.googlesource.com/c/1443503Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59187}

src/profiler/tick-sample.cc

@@ -5,6 +5,7 @@
 #include "src/profiler/tick-sample.h"
 
 #include "include/v8-profiler.h"
+#include "src/asan.h"
 #include "src/counters.h"
 #include "src/frames-inl.h"
 #include "src/msan.h"
@@ -169,7 +170,8 @@ DISABLE_ASAN void TickSample::Init(Isolate* v8_isolate,
     external_callback_entry = info.external_callback_entry;
   } else if (frames_count) {
     // sp register may point at an arbitrary place in memory, make
-    // sure MSAN doesn't complain about it.
+    // sure sanitizers don't complain about it.
+    ASAN_UNPOISON_MEMORY_REGION(regs.sp, sizeof(void*));
     MSAN_MEMORY_IS_INITIALIZED(regs.sp, sizeof(void*));
     // Sample potential return address value for frameless invocation of
     // stubs (we'll figure out later, if this value makes sense).