[WebAssembly] Print error message for llvm.clear_cache intrinsic

Summary:
Wasm does not currently support `llvm.clear_cache` intrinsic, and this
prints a proper error message instead of segfault.

Reviewers: dschuff, sbc100, sunfish

Subscribers: jgravelle-google, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64322

llvm-svn: 365731
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
index ce4ef14..b3c7f3d 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
@@ -89,6 +89,10 @@
   void ReplaceNodeResults(SDNode *N, SmallVectorImpl<SDValue> &Results,
                           SelectionDAG &DAG) const override;
 
+  const char *getClearCacheBuiltinName() const override {
+    report_fatal_error("llvm.clear_cache is not supported on wasm");
+  }
+
   // Custom lowering hooks.
   SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override;
   SDValue LowerFrameIndex(SDValue Op, SelectionDAG &DAG) const;