win, build: arm64 port script and doc changes

BUILDING.md

@@ -416,9 +416,19 @@ Prerequisites:
   and tools which can be included in the global `PATH`.
 * The [NetWide Assembler](http://www.nasm.us/), for OpenSSL assembler modules.
   If not installed in the default location, it needs to be manually added
-  to `PATH`. A build with the `openssl-no-asm` option does not need this.
+  to `PATH`. A build with the `openssl-no-asm` option does not need this, nor
+  does a build targeting ARM64 Windows.
 * **Optional** (to build the MSI): the [WiX Toolset v3.11](http://wixtoolset.org/releases/)
   and the [Wix Toolset Visual Studio 2017 Extension](https://marketplace.visualstudio.com/items?itemName=RobMensching.WixToolsetVisualStudio2017Extension).
+* **Optional** Requirements for compiling for Windows 10 on ARM (ARM64):
+    * ARM64 Windows build machine
+        * Due to a GYP limitation, this is required to run compiled code
+          generation tools (like V8's builtins and mksnapshot tools)
+    * Visual Studio 15.9.0 or newer
+    * Visual Studio optional components
+        * Visual C++ compilers and libraries for ARM64
+        * Visual C++ ATL for ARM64
+    * Windows 10 SDK 10.0.17763.0 or newer
 
 If the path to your build directory contains a space or a non-ASCII character,
 the build will likely fail.

common.gypi

@@ -271,6 +271,14 @@
               }],
             ],
           }],
+          ['target_arch=="arm64"', {
+            'TargetMachine' : 0, # /MACHINE:ARM64 is inferred from the input files.
+            'target_conditions': [
+              ['_type=="executable"', {
+                'AdditionalOptions': [ '/SubSystem:Console' ],
+              }],
+            ],
+          }],
         ],
         'GenerateDebugInformation': 'true',
         'SuppressStartupBanner': 'true',
@@ -296,6 +304,9 @@
       [ 'target_arch=="x64"', {
         'msvs_configuration_platform': 'x64',
       }],
+      [ 'target_arch=="arm64"', {
+        'msvs_configuration_platform': 'arm64',
+      }],
       ['asan == 1 and OS != "mac"', {
         'cflags+': [
           '-fno-omit-frame-pointer',

configure.py

@@ -748,7 +748,7 @@ def get_gas_version(cc):
 # quite prepared to go that far yet.
 def check_compiler(o):
   if sys.platform == 'win32':
-    if not options.openssl_no_asm:
+    if not options.openssl_no_asm and options.dest_cpu in ('x86', 'x64'):
       nasm_version = get_nasm_version('nasm')
       o['variables']['nasm_version'] = nasm_version
       if nasm_version == 0:

tools/bootstrap/README.md

@@ -23,7 +23,7 @@ get-boxstarter -Force
 Install-BoxstarterPackage https://raw.githubusercontent.com/nodejs/node/master/tools/bootstrap/windows_boxstarter -DisableReboots
 ```
 
-Entire installation will take up about 8 GB of disk space.
+Entire installation will take up about 10 GB of disk space.
 
 ## Linux
 

tools/bootstrap/windows_boxstarter

@@ -18,7 +18,7 @@ choco install python2 -y
 
 # Installs VS 2017 Build Tools
 choco install visualstudio2017buildtools -y
-choco install visualstudio2017-workload-vctools -y
+choco install visualstudio2017-workload-vctools -y --params="--add Microsoft.VisualStudio.Component.VC.Tools.ARM64 --add Microsoft.VisualStudio.Component.VC.ATL.ARM64"
 
 # NASM
 choco install nasm -y

vcbuild.bat

@@ -67,6 +67,7 @@ if /i "%1"=="clean"         set target=Clean&goto arg-ok
 if /i "%1"=="ia32"          set target_arch=x86&goto arg-ok
 if /i "%1"=="x86"           set target_arch=x86&goto arg-ok
 if /i "%1"=="x64"           set target_arch=x64&goto arg-ok
+if /i "%1"=="arm64"         set target_arch=arm64&goto arg-ok
 if /i "%1"=="vs2017"        set target_env=vs2017&goto arg-ok
 if /i "%1"=="noprojgen"     set noprojgen=1&goto arg-ok
 if /i "%1"=="projgen"       set projgen=1&goto arg-ok
@@ -192,7 +193,8 @@ if "%target%"=="Clean" rmdir /S /Q %~dp0deps\icu
 call tools\msvs\find_python.cmd
 if errorlevel 1 goto :exit
 
-if not defined openssl_no_asm call tools\msvs\find_nasm.cmd
+REM NASM is only needed on IA32 and x86_64.
+if not defined openssl_no_asm if "%target_arch%" NEQ "arm64" call tools\msvs\find_nasm.cmd
 if errorlevel 1 echo Could not find NASM, install it or build with openssl-no-asm. See BUILDING.md.
 
 call :getnodeversion || exit /b 1
@@ -303,6 +305,7 @@ set "msbcpu=/m:2"
 if "%NUMBER_OF_PROCESSORS%"=="1" set "msbcpu=/m:1"
 set "msbplatform=Win32"
 if "%target_arch%"=="x64" set "msbplatform=x64"
+if "%target_arch%"=="arm64" set "msbplatform=ARM64"
 if "%target%"=="Build" (
   if defined no_cctest set target=rename_node_bin_win
   if "%test_args%"=="" set target=rename_node_bin_win