[WebAssembly] Initial WebAssembly backend

This WebAssembly backend is just a skeleton at this time and is not yet
functional.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241022 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/WebAssembly/WebAssemblyTargetTransformInfo.cpp

@@ -0,0 +1,28 @@
+//===-- WebAssemblyTargetTransformInfo.cpp - WebAssembly-specific TTI -----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file defines the WebAssembly-specific TargetTransformInfo
+/// implementation.
+///
+//===----------------------------------------------------------------------===//
+
+#include "WebAssemblyTargetTransformInfo.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Target/CostTable.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasmtti"
+
+TargetTransformInfo::PopcntSupportKind
+WebAssemblyTTIImpl::getPopcntSupport(unsigned TyWidth) {
+  assert(isPowerOf2_32(TyWidth) && "Ty width must be power of 2");
+  // TODO: Make Math.popcount32 happen in WebAssembly.
+  return TTI::PSK_Software;
+}