Hardware-assisted AddressSanitizer (llvm part).

Summary:
This is LLVM instrumentation for the new HWASan tool. It is basically
a stripped down copy of ASan at this point, w/o stack or global
support. Instrumenation adds a global constructor + runtime callbacks
for every load and store.

HWASan comes with its own IR attribute.

A brief design document can be found in
clang/docs/HardwareAssistedAddressSanitizerDesign.rst (submitted earlier).

Reviewers: kcc, pcc, alekseyshl

Subscribers: srhines, mehdi_amini, mgorny, javed.absar, eraman, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D40932

llvm-svn: 320217
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 76e295c..e2c1eaf 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1299,7 +1299,10 @@
 /// non-local by performing PHI construction.
 bool GVN::processNonLocalLoad(LoadInst *LI) {
   // non-local speculations are not allowed under asan.
-  if (LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeAddress))
+  if (LI->getParent()->getParent()->hasFnAttribute(
+          Attribute::SanitizeAddress) ||
+      LI->getParent()->getParent()->hasFnAttribute(
+          Attribute::SanitizeHWAddress))
     return false;
 
   // Step 1: Find the non-local dependencies of the load.