[WebAssembly] Support for atomic.wait / atomic.wake instructions

Summary:
This adds support for atomic.wait / atomic.wake instructions in the wasm
thread proposal.

Reviewers: dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D49395

llvm-svn: 338770
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
index 7981949..8e22f90 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
@@ -66,6 +66,9 @@
 
   EVT getSetCCResultType(const DataLayout &DL, LLVMContext &Context,
                          EVT VT) const override;
+  bool getTgtMemIntrinsic(IntrinsicInfo &Info, const CallInst &I,
+                          MachineFunction &MF,
+                          unsigned Intrinsic) const override;
 
   SDValue LowerCall(CallLoweringInfo &CLI,
                     SmallVectorImpl<SDValue> &InVals) const override;