From 4b83f714c821d6d4d2306673ee3a87907cfec80e Mon Sep 17 00:00:00 2001
From: Ivan Trubach <mr.trubach@icloud.com>
Date: Fri, 19 Jul 2024 10:45:13 +0300
Subject: [PATCH] build: support setting an emulator from configure script
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V8’s JIT infrastructure requires binaries such as mksnapshot to be run
during the build. However, these binaries must have the same bit-width
as the host platform (e.g. a x86_64 build platform targeting ARMv6 needs
to produce a 32-bit binary).

To work around this issue, allow building the binaries for the host
platform and running them on the build platform with an emulator.

Based on Buildroot’s nodejs-src 0001-add-qemu-wrapper-support.patch.
https://gitlab.com/buildroot.org/buildroot/-/blob/c1d5eada4d4db9eeaa1c44dd1dea95a67c8a70ca/package/nodejs/nodejs-src/0001-add-qemu-wrapper-support.patch

Upstream: https://github.com/nodejs/node/pull/53899
---
 common.gypi              |  1 +
 configure.py             | 14 ++++++++++++++
 node.gyp                 |  3 +++
 tools/v8_gypfiles/v8.gyp |  4 ++++
 4 files changed, 22 insertions(+)

diff --git a/common.gypi b/common.gypi
index ec92c9df4c..6474495ab6 100644
--- a/common.gypi
+++ b/common.gypi
@@ -13,6 +13,7 @@
     'enable_pgo_generate%': '0',
     'enable_pgo_use%': '0',
     'python%': 'python',
+    'emulator%': [],
 
     'node_shared%': 'false',
     'force_dynamic_crt%': 0,
diff --git a/configure.py b/configure.py
index 82916748fd..10dc0becbb 100755
--- a/configure.py
+++ b/configure.py
@@ -112,6 +112,12 @@ parser.add_argument('--dest-cpu',
     choices=valid_arch,
     help=f"CPU architecture to build for ({', '.join(valid_arch)})")
 
+parser.add_argument('--emulator',
+    action='store',
+    dest='emulator',
+    default=None,
+    help='emulator command that can run executables built for the target system')
+
 parser.add_argument('--cross-compiling',
     action='store_true',
     dest='cross_compiling',
@@ -2160,6 +2166,14 @@ write('config.mk', do_not_edit + config_str)
 gyp_args = ['--no-parallel', '-Dconfiguring_node=1']
 gyp_args += ['-Dbuild_type=' + config['BUILDTYPE']]
 
+if options.emulator is not None:
+  if not options.cross_compiling:
+    # Note that emulator is a list so we have to quote the variable.
+    gyp_args += ['-Demulator=' + shlex.quote(options.emulator)]
+  else:
+    # TODO: perhaps use emulator for tests?
+    warn('The `--emulator` option has no effect when cross-compiling.')
+
 if options.use_ninja:
   gyp_args += ['-f', 'ninja-' + flavor]
 elif flavor == 'win' and sys.platform != 'msys':
diff --git a/node.gyp b/node.gyp
index 08cb3f38e8..515b305933 100644
--- a/node.gyp
+++ b/node.gyp
@@ -332,6 +332,7 @@
                     '<(SHARED_INTERMEDIATE_DIR)/node_snapshot.cc',
                   ],
                   'action': [
+                    '<@(emulator)',
                     '<(node_mksnapshot_exec)',
                     '--build-snapshot',
                     '<(node_snapshot_main)',
@@ -351,6 +352,7 @@
                     '<(SHARED_INTERMEDIATE_DIR)/node_snapshot.cc',
                   ],
                   'action': [
+                    '<@(emulator)',
                     '<@(_inputs)',
                     '<@(_outputs)',
                   ],
@@ -1520,6 +1522,7 @@
                '<(PRODUCT_DIR)/<(node_core_target_name).def',
              ],
              'action': [
+               '<@(emulator)',
                '<(PRODUCT_DIR)/gen_node_def.exe',
                '<@(_inputs)',
                '<@(_outputs)',
diff --git a/tools/v8_gypfiles/v8.gyp b/tools/v8_gypfiles/v8.gyp
index ba8b161f0f..d5c90dad50 100644
--- a/tools/v8_gypfiles/v8.gyp
+++ b/tools/v8_gypfiles/v8.gyp
@@ -99,6 +99,7 @@
             '<@(torque_outputs_inc)',
           ],
           'action': [
+            '<@(emulator)',
             '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)torque<(EXECUTABLE_SUFFIX)',
             '-o', '<(SHARED_INTERMEDIATE_DIR)/torque-generated',
             '-v8-root', '<(V8_ROOT)',
@@ -219,6 +220,7 @@
           'action': [
             '<(python)',
             '<(V8_ROOT)/tools/run.py',
+            '<@(emulator)',
             '<@(_inputs)',
             '<@(_outputs)',
           ],
@@ -442,6 +444,7 @@
              }],
           ],
           'action': [
+            '<@(emulator)',
             '>@(_inputs)',
             '>@(mksnapshot_flags)',
           ],
@@ -1577,6 +1580,7 @@
           'action': [
             '<(python)',
             '<(V8_ROOT)/tools/run.py',
+            '<@(emulator)',
             '<@(_inputs)',
             '<@(_outputs)',
           ],
-- 
2.44.1