XLA backend for Lc0 (LeelaChessZero#1949)

(cherry picked from commit 04f73fc)

meson.build

@@ -623,6 +623,22 @@ if get_option('build_backends')
   endif
 
 
+  ## ~~~~~~~~
+  ## XLA
+  ## ~~~~~~~~
+  if get_option('xla')
+      files += [
+        'src/neural/xla/hlo_builder.cc',
+        'src/neural/xla/network_xla.cc',
+        'src/neural/xla/onnx2hlo.cc',
+        'src/neural/xla/print_hlo.cc',
+        'src/neural/xla/pjrt.cc',
+        'src/neural/xla/xla_runner.cc',
+      ]
+      files += gen_proto_src.process('src/neural/xla/hlo.proto',
+          preserve_path_from : meson.current_source_dir() + '/src/')
+      deps += cc.find_library('dl', required: false)
+  endif
 
 endif # if get_option('build_backends')
 

meson_options.txt

@@ -187,3 +187,8 @@ option('onnx_include',
        type: 'string',
        value: 'D:/IDE/Microsoft Visual Studio/Projects/lc0/subprojects/onnx/include',
        description: 'Paths to ONNX runtime includes')
+
+option('xla',
+       type: 'boolean',
+       value: false,
+       description: 'Enable XLA backend')

scripts/compile_proto.py

@@ -64,6 +64,7 @@
     'package',
     'message',
     'optional',
+    'required',
     'repeated',
     'enum',
 ] + list(TYPES.keys())