[build] Generate AOT snapshots in the SDK as dylibs on Mac.

Change-Id: I95efe7342e595b44bfce1a15229b926a721aea82
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/499480
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

samples/embedder/BUILD.gn

@@ -70,14 +70,6 @@ _all_configs = [
     dart_shared_lib = "../../runtime/engine:dart_engine_aot_shared"
     dart_static_lib = "../../runtime/engine:dart_engine_aot_static"
     snapshot_target = "aot_snapshot"
-
-    # AOT snapshots as shared libraries on Windows are not
-    # supported, and in fact we don't build AOT samples on
-    # Windows. However, GN evaluation model will still
-    # evaluate the `aot_snapshot` template on Windows,
-    # and it will fail the assert if as_shared_library is
-    # true, and the current platform is Windows.
-    as_shared_library = !is_win
   },
 ]
 

utils/aot_snapshot.gni

@@ -104,104 +104,39 @@ template("aot_snapshot") {
     }
   }
 
-  # Whether to build an AOT snapshot, which can be opened by dlopen.
-  # Ignore this option on Linux, as the default app-aot-elf AOT
-  # snapshot already can be used with dlopen on Linux.
-  as_shared_library = defined(invoker.as_shared_library) &&
-                      invoker.as_shared_library && !is_linux
+  # Create a snapshot from kernel built above.
+  gen_snapshot_action(target_name) {
+    if (defined(invoker.pool)) {
+      pool = invoker.pool
+    }
+    deps = extra_deps + [ ":${target_name}_dill" ]
 
-  assert(!(as_shared_library && is_win),
-         "AOT Snapshots as shared libraries are not supported on Windows")
+    inputs = extra_inputs
 
-  if (!as_shared_library) {
-    # Create a snapshot from kernel built above.
-    gen_snapshot_action(target_name) {
-      if (defined(invoker.pool)) {
-        pool = invoker.pool
-      }
-      deps = extra_deps + [ ":${target_name}_dill" ]
+    outputs = [ output ]
 
-      inputs = extra_inputs
-
-      outputs = [ output ]
-
-      abs_output = rebase_path(output)
+    abs_output = rebase_path(output)
 
+    # TODO(60813): Generate PE DLL on Windows.
+    if (is_mac) {
+      vm_args = [
+                  "--deterministic",
+                  "--snapshot-kind=app-aot-macho-dylib",
+                  "--macho=$abs_output",
+                ] + gen_snapshot_args
+    } else {
       vm_args = [
                   "--deterministic",
                   "--snapshot-kind=app-aot-elf",
                   "--elf=$abs_output",
                 ] + gen_snapshot_args
-      if (defined(invoker.vm_args)) {
-        vm_args += invoker.vm_args
-      }
-
-      args = [ rebase_path(dill) ]
-
-      force_product_mode = product_mode
     }
-  } else {
-    assembly = "$target_gen_dir/$name.S"
-    dill_target_name = ":${target_name}_dill"
-
-    # Create an assembly snapshot from kernel built above.
-    assembly_target_name = target_name + "_assembly"
-    gen_snapshot_action(assembly_target_name) {
-      if (defined(invoker.pool)) {
-        pool = invoker.pool
-      }
-      deps = extra_deps + [ dill_target_name ]
-
-      inputs = extra_inputs
-
-      outputs = [ assembly ]
-
-      abs_output = rebase_path(assembly)
-      vm_args = [
-                  "--deterministic",
-                  "--snapshot-kind=app-aot-assembly",
-                  "--assembly=$abs_output",
-                ] + gen_snapshot_args
-
-      args = [ rebase_path(dill) ]
-
-      force_product_mode = product_mode
+    if (defined(invoker.vm_args)) {
+      vm_args += invoker.vm_args
     }
 
-    # build a shared library from assembly.
-    shared_library_target_name = target_name + "_shared_library"
-    shared_library(shared_library_target_name) {
-      sources = [ assembly ]
-      deps = [ ":${assembly_target_name}" ]
-    }
+    args = [ rebase_path(dill) ]
 
-    output_prefix = "lib"
-    output_extension = ""
-
-    if (current_os == "mac" || current_os == "ios" || current_os == "watchos") {
-      output_extension = "dylib"
-    } else if (current_os == "win") {
-      output_extension = "dll"
-      output_prefix = ""
-    } else if (current_os == "unknown" && current_cpu == "wasm32") {
-      output_extension = "wasm"
-    } else {
-      output_extension = "so"
-    }
-
-    shared_library_output_file_name =
-        "$output_prefix$shared_library_target_name"
-    if (output_extension != "") {
-      shared_library_output_file_name += ".$output_extension"
-    }
-
-    # copy shared library to the same output, as when
-    # `as_shared_library` is False.
-    copy(target_name) {
-      sources = [ "$root_out_dir/$shared_library_output_file_name" ]
-      outputs = [ output ]
-
-      deps = [ ":${shared_library_target_name}" ]
-    }
+    force_product_mode = product_mode
   }
 }