Raise an informative error when running on macOS under Rosetta 2.

Current users only get a cryptic "Illegal instruction" crash.

Context: https://github.com/deepmind/mujoco/issues/611
PiperOrigin-RevId: 491705647
Change-Id: I1285897a36e858300ee3d125957e90754be9a7f7

src/engine/engine_crossplatform.c

@@ -0,0 +1,39 @@
+// Copyright 2022 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#if defined(__APPLE__) && defined(__AVX__)
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/sysctl.h>
+
+__attribute__((weak, visibility("default"))) void _mj_rosettaError(const char* msg) {
+  fprintf(stderr, "%s\n", msg);
+  __asm__ __volatile__ ("ud2");  // raises SIGILL but leave this function at the top of the stack
+}
+
+__attribute__((constructor(10000), target("no-avx"))) static void _mj_checkRosetta() {
+  int is_translated = 0;
+  {
+    size_t len = sizeof(is_translated);
+    if (sysctlbyname("sysctl.proc_translated", &is_translated, &len, NULL, 0)) {
+      is_translated = 0;
+    }
+  }
+  if (is_translated) {
+    _mj_rosettaError("MuJoCo cannot be run under Rosetta 2 on an Apple Silicon machine.");
+  }
+}
+
+#endif  // defined(__APPLE__) && defined(__AVX__)