build: add option to build v8 with GN

PR-URL: #19201
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

common.gypi

@@ -51,8 +51,8 @@
         'obj_dir': '<(PRODUCT_DIR)/obj',
         'v8_base': '<(PRODUCT_DIR)/obj/deps/v8/gypfiles/libv8_base.a',
        }, {
-         'obj_dir%': '<(PRODUCT_DIR)/obj.target',
-         'v8_base%': '<(PRODUCT_DIR)/obj.target/deps/v8/gypfiles/libv8_base.a',
+        'obj_dir%': '<(PRODUCT_DIR)/obj.target',
+        'v8_base': '<(PRODUCT_DIR)/obj.target/deps/v8/gypfiles/libv8_base.a',
       }],
       ['OS == "win"', {
         'os_posix': 0,
@@ -63,10 +63,19 @@
         'os_posix': 1,
         'v8_postmortem_support%': 'true',
       }],
-      ['OS== "mac"', {
+      ['OS == "mac"', {
         'obj_dir%': '<(PRODUCT_DIR)/obj.target',
         'v8_base': '<(PRODUCT_DIR)/libv8_base.a',
       }],
+      ['build_v8_with_gn == "true"', {
+        'conditions': [
+          ['GENERATOR == "ninja"', {
+            'v8_base': '<(PRODUCT_DIR)/obj/deps/v8/gypfiles/v8_monolith.gen/gn/obj/libv8_monolith.a',
+          }, {
+            'v8_base': '<(PRODUCT_DIR)/obji.target/v8_monolith/geni/gn/obj/libv8_monolith.a',
+          }],
+        ],
+      }],
       ['openssl_fips != ""', {
         'openssl_product': '<(STATIC_LIB_PREFIX)crypto<(STATIC_LIB_SUFFIX)',
       }, {

configure

@@ -55,6 +55,10 @@ sys.path.insert(0, 'tools')
 import getmoduleversion
 from gyp_node import run_gyp
 
+# imports in deps/v8/tools/node
+sys.path.insert(0, os.path.join('deps', 'v8', 'tools', 'node'))
+from fetch_deps import FetchDeps
+
 # parse our options
 parser = optparse.OptionParser()
 
@@ -548,6 +552,12 @@ parser.add_option('--without-bundled-v8',
     help='do not use V8 includes from the bundled deps folder. ' +
          '(This mode is not officially supported for regular applications)')
 
+parser.add_option('--build-v8-with-gn',
+    action='store_true',
+    dest='build_v8_with_gn',
+    default=False,
+    help='build V8 using GN instead of gyp')
+
 # Create compile_commands.json in out/Debug and out/Release.
 parser.add_option('-C',
     action='store_true',
@@ -1060,6 +1070,14 @@ def configure_v8(o):
     o['variables']['test_isolation_mode'] = 'noop'  # Needed by d8.gyp.
   if options.without_bundled_v8 and options.enable_d8:
     raise Exception('--enable-d8 is incompatible with --without-bundled-v8.')
+  if options.without_bundled_v8 and options.build_v8_with_gn:
+    raise Exception(
+        '--build-v8-with-gn is incompatible with --without-bundled-v8.')
+  if options.build_v8_with_gn:
+    v8_path = os.path.join('deps', 'v8')
+    print('Fetching dependencies to build V8 with GN')
+    options.build_v8_with_gn = FetchDeps(v8_path)
+  o['variables']['build_v8_with_gn'] = b(options.build_v8_with_gn)
 
 
 def configure_openssl(o):

node.gypi

@@ -59,9 +59,15 @@
       'dependencies': [ 'deps/v8/gypfiles/d8.gyp:d8' ],
     }],
     [ 'node_use_bundled_v8=="true"', {
-      'dependencies': [
-        'deps/v8/gypfiles/v8.gyp:v8',
-        'deps/v8/gypfiles/v8.gyp:v8_libplatform'
+      'conditions': [
+        [ 'build_v8_with_gn=="true"', {
+          'dependencies': ['deps/v8/gypfiles/v8.gyp:v8_monolith'],
+        }, {
+          'dependencies': [
+            'deps/v8/gypfiles/v8.gyp:v8',
+            'deps/v8/gypfiles/v8.gyp:v8_libplatform',
+          ],
+        }],
       ],
     }],
     [ 'node_use_v8_platform=="true"', {
@@ -111,7 +117,6 @@
       'defines': [ 'NODE_NO_BROWSER_GLOBALS' ],
     } ],
     [ 'node_use_bundled_v8=="true" and v8_postmortem_support=="true"', {
-      'dependencies': [ 'deps/v8/gypfiles/v8.gyp:postmortem-metadata' ],
       'conditions': [
         # -force_load is not applicable for the static library
         [ 'force_load=="true"', {
@@ -121,6 +126,10 @@
             ],
           },
         }],
+        # when building with GN, the v8_monolith target already includes postmortem metadata
+        [ 'build_v8_with_gn=="false"', {
+          'dependencies': [ 'deps/v8/gypfiles/v8.gyp:postmortem-metadata' ],
+        }],
       ],
     }],
     [ 'node_shared_zlib=="false"', {