[PATCH] D20485: [esan] Add working set base runtime library

[Derek Bruening via llvm-commits]

bruening added inline comments.

================
Comment at: lib/esan/working_set.cpp:53
@@ +52,3 @@
+  while (I < NumLines && (uptr)Shadow % 4 != 0) {
+    if ((*Shadow & ShadowAccessedVal) != ShadowAccessedVal)
+      *Shadow |= ShadowAccessedVal;
----------------
aizatsky wrote:
> I don't really see a reason to do an if() check here. Why not blindly "*Shadow |= ShadowAccessedVal"? Is it really faster? I would guess that having a branch is not very good for performance?
The check is faster.  In every shadow tool we have ever made it is faster to load, compare, and only store if the value is not already there, than to perform a blind store.




http://reviews.llvm.org/D20485