[wasm] Initial commit for the Int64Reducer.

BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 if (is_android) {
@@ skipping 765 matching lines @@
     "src/compiler/greedy-allocator.cc",
     "src/compiler/greedy-allocator.h",
     "src/compiler/instruction-codes.h",
     "src/compiler/instruction-scheduler.cc",
     "src/compiler/instruction-scheduler.h",
     "src/compiler/instruction-selector-impl.h",
     "src/compiler/instruction-selector.cc",
     "src/compiler/instruction-selector.h",
     "src/compiler/instruction.cc",
     "src/compiler/instruction.h",
+    "src/compiler/int64-lowering.cc",
+    "src/compiler/int64-lowering.h",
     "src/compiler/interpreter-assembler.cc",
     "src/compiler/interpreter-assembler.h",
     "src/compiler/js-builtin-reducer.cc",
     "src/compiler/js-builtin-reducer.h",
     "src/compiler/js-call-reducer.cc",
     "src/compiler/js-call-reducer.h",
     "src/compiler/js-context-relaxation.cc",
     "src/compiler/js-context-relaxation.h",
     "src/compiler/js-context-specialization.cc",
     "src/compiler/js-context-specialization.h",
@@ skipping 1185 matching lines @@
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [
     ":internal_config",
     ":features",
     ":toolchain",
   ]
 }