[WebAssembly] Implement isCheapToSpeculateCtlz and isCheapToSpeculateCttz.

This unbreaks test/CodeGen/WebAssembly/i32.ll and
test/CodeGen/WebAssembly/i64.ll after r224899.

llvm-svn: 253617
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index bae4f52..dbfe00e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -228,6 +228,16 @@
   return TargetLowering::getRegForInlineAsmConstraint(TRI, Constraint, VT);
 }
 
+bool WebAssemblyTargetLowering::isCheapToSpeculateCttz() const {
+  // Assume ctz is a relatively cheap operation.
+  return true;
+}
+
+bool WebAssemblyTargetLowering::isCheapToSpeculateCtlz() const {
+  // Assume clz is a relatively cheap operation.
+  return true;
+}
+
 //===----------------------------------------------------------------------===//
 // WebAssembly Lowering private implementation.
 //===----------------------------------------------------------------------===//