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/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index a00e6f7..aa05512 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3607,7 +3607,8 @@
   case Intrinsic::lifetime_start:
     // Asan needs to poison memory to detect invalid access which is possible
     // even for empty lifetime range.
-    if (II->getFunction()->hasFnAttribute(Attribute::SanitizeAddress))
+    if (II->getFunction()->hasFnAttribute(Attribute::SanitizeAddress) ||
+        II->getFunction()->hasFnAttribute(Attribute::SanitizeHWAddress))
       break;
 
     if (removeTriviallyEmptyRange(*II, Intrinsic::lifetime_start,