[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/MCTargetDesc/WebAssemblyMCAsmInfo.cpp

@@ -0,0 +1,53 @@
+//===-- WebAssemblyMCAsmInfo.cpp - WebAssembly asm properties -------------===//
+//
+//                     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 contains the declarations of the WebAssemblyMCAsmInfo
+/// properties.
+///
+//===----------------------------------------------------------------------===//
+
+#include "WebAssemblyMCAsmInfo.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/Support/CommandLine.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-mc-asm-info"
+
+WebAssemblyMCAsmInfo::~WebAssemblyMCAsmInfo() {}
+
+WebAssemblyMCAsmInfo::WebAssemblyMCAsmInfo(const Triple &T) {
+  PointerSize = CalleeSaveStackSlotSize = T.isArch64Bit();
+
+  // TODO: What should MaxInstLength be?
+
+  PrivateGlobalPrefix = "";
+  PrivateLabelPrefix = "";
+
+  UseDataRegionDirectives = true;
+
+  Data8bitsDirective = "\t.int8\t";
+  Data16bitsDirective = "\t.int16\t";
+  Data32bitsDirective = "\t.int32\t";
+  Data64bitsDirective = "\t.int64\t";
+
+  AlignmentIsInBytes = false;
+  COMMDirectiveAlignmentIsInBytes = false;
+  LCOMMDirectiveAlignmentType = LCOMM::Log2Alignment;
+
+  HasDotTypeDotSizeDirective = false;
+  HasSingleParameterDotFile = false;
+
+  SupportsDebugInformation = true;
+
+  // For now, WebAssembly does not support exceptions.
+  ExceptionsType = ExceptionHandling::None;
+
+  // TODO: UseIntegratedAssembler?
+}