[dart2wasm] Add JS compatibility mode.

The purpose of the wasm_js_compatibility target is to facilitate experiments with a JS compatibility mode for Dart2Wasm. Initially, we're just going to focus on typed data, but this will give us a place to experiment with moving List and String to JS as well.

In addition, someday down the road we hope to experiment with two additional compatibility changes:
1) Exclusively using double for all Dart numbers
2) Allowing undefined to flow as null.

The two major benefits of this approach are:
1) Much faster JS interop
2) To make it easier to bring up Dart2JS applications on Dart2Wasm

The only downside will be access overhead on the Wasm side, but the JS builtins proposal could potentially bring us close to parity with Wasm builtins someday.

Tested: Wasm specific trivial refactor.
Change-Id: I2c09426b6999507c1de6e584e9bc7072a088bda9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/313240
Commit-Queue: Joshua Litt <joshualitt@google.com>
Reviewed-by: Ömer Ağacan <omersa@google.com>
Reviewed-by: William Hesse <whesse@google.com>

BUILD.gn

@@ -110,6 +110,7 @@ group("dart2js") {
 group("dart2wasm_platform") {
   deps = [
     ":runtime_precompiled",
+    "utils/dart2wasm:compile_dart2wasm_js_compatibility_platform",
     "utils/dart2wasm:compile_dart2wasm_platform",
     "utils/dart2wasm:compile_dart2wasm_stringref_platform",
     "utils/dart2wasm:dart2wasm_snapshot",

pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart

@@ -4500,7 +4500,7 @@ const MessageCode messageFastaUsageLong =
     Read the SDK platform from <file>, which should be in Dill/Kernel IR format
     and contain the Dart SDK.
 
-  --target=dart2js|dart2js_server|dart2wasm|dart2wasm_stringref|dart_runner|dartdevc|flutter|flutter_runner|none|vm
+  --target=dart2js|dart2js_server|dart2wasm|dart2wasm_js_compatibility|dart2wasm_stringref|dart_runner|dartdevc|flutter|flutter_runner|none|vm
     Specify the target configuration.
 
   --enable-asserts

pkg/dart2wasm/lib/target.dart

@@ -34,11 +34,17 @@ import 'package:dart2wasm/ffi_native_transformer.dart' as wasmFfiNativeTrans;
 import 'package:dart2wasm/records.dart' show RecordShape;
 import 'package:dart2wasm/transformers.dart' as wasmTrans;
 
+enum Mode {
+  regular,
+  stringref,
+  jsCompatibility,
+}
+
 class WasmTarget extends Target {
-  WasmTarget({this.removeAsserts = true, this.useStringref = false});
+  WasmTarget({this.removeAsserts = true, this.mode = Mode.regular});
 
   bool removeAsserts;
-  bool useStringref;
+  Mode mode;
   Class? _growableList;
   Class? _immutableList;
   Class? _wasmDefaultMap;
@@ -59,7 +65,27 @@ class WasmTarget extends Target {
   Verification get verification => const WasmVerification();
 
   @override
-  String get name => useStringref ? 'wasm_stringref' : 'wasm';
+  String get name {
+    switch (mode) {
+      case Mode.regular:
+        return 'wasm';
+      case Mode.stringref:
+        return 'wasm_stringref';
+      case Mode.jsCompatibility:
+        return 'wasm_js_compatibility';
+    }
+  }
+
+  String get platformFile {
+    switch (mode) {
+      case Mode.regular:
+        return 'dart2wasm_platform.dill';
+      case Mode.stringref:
+        return 'dart2wasm_stringref_platform.dill';
+      case Mode.jsCompatibility:
+        return 'dart2wasm_js_compatibility_platform.dill';
+    }
+  }
 
   @override
   TargetFlags get flags => TargetFlags();

pkg/front_end/lib/src/compute_platform_binaries_location.dart

@@ -86,6 +86,17 @@ String? computePlatformDillName(
           break;
       }
       break;
+    case 'wasm_js_compatibility':
+      switch (nnbdMode) {
+        case NnbdMode.Strong:
+          return 'dart2wasm_js_compatibility_outline.dill';
+        //TODO(johnniwinther): Support using the full dill.
+        //return 'dart2wasm_js_compatibility_platform.dill';
+        case NnbdMode.Weak:
+        case NnbdMode.Agnostic:
+          break;
+      }
+      break;
     default:
       break;
   }

pkg/front_end/messages.yaml

@@ -2271,7 +2271,7 @@ FastaUsageLong:
         Read the SDK platform from <file>, which should be in Dill/Kernel IR format
         and contain the Dart SDK.
 
-      --target=dart2js|dart2js_server|dart2wasm|dart2wasm_stringref|dart_runner|dartdevc|flutter|flutter_runner|none|vm
+      --target=dart2js|dart2js_server|dart2wasm|dart2wasm_js_compatibility|dart2wasm_stringref|dart_runner|dartdevc|flutter|flutter_runner|none|vm
         Specify the target configuration.
 
       --enable-asserts

pkg/front_end/test/spell_checking_list_common.txt

@@ -738,6 +738,7 @@ dart
 dart2js
 dart2wasm
 dart2wasm_stringref
+dart2wasm_js_compatibility
 dartdevc
 data
 date

pkg/front_end/tool/_fasta/additional_targets.dart

@@ -12,6 +12,8 @@ import 'package:dev_compiler/src/kernel/target.dart' show DevCompilerTarget;
 
 import 'package:dart2wasm/target.dart' show WasmTarget;
 
+import 'package:dart2wasm/target.dart' as wasm show Mode;
+
 import 'package:vm/target/install.dart' as vm_target_install
     show installAdditionalTargets;
 
@@ -25,6 +27,8 @@ void installAdditionalTargets() {
   targets["dartdevc"] = (TargetFlags flags) => new DevCompilerTarget(flags);
   targets["dart2wasm"] = (TargetFlags flags) => new WasmTarget();
   targets["dart2wasm_stringref"] =
-      (TargetFlags flags) => new WasmTarget(useStringref: true);
+      (TargetFlags flags) => new WasmTarget(mode: wasm.Mode.stringref);
+  targets["dart2wasm_js_compatibility"] =
+      (TargetFlags flags) => new WasmTarget(mode: wasm.Mode.jsCompatibility);
   vm_target_install.installAdditionalTargets();
 }

pkg/vm/test/common_test_utils.dart

@@ -37,9 +37,7 @@ Future<Component> compileTestCaseToKernelProgram(Uri sourceUri,
   Directory? tempDirectory;
   try {
     final platformFileName = (target is WasmTarget)
-        ? target.useStringref
-            ? 'dart2wasm_stringref_platform.dill'
-            : 'dart2wasm_platform.dill'
+        ? target.platformFile
         : 'vm_platform_strong.dill';
     final platformKernel =
         computePlatformBinariesLocation().resolve(platformFileName);

sdk/BUILD.gn

@@ -70,6 +70,8 @@ declare_args() {
 # ........dart2wasm_platform.dill (if not on ia32)
 # ........dart2wasm_stringref_outline.dill (if not on ia32)
 # ........dart2wasm_stringref_platform.dill (if not on ia32)
+# ........dart2wasm_js_compatibility_outline.dill (if not on ia32)
+# ........dart2wasm_js_compatibility_platform.dill (if not on ia32)
 # ........ddc_outline.dill
 # ........ddc_platform.dill
 # ........vm_platform_strong.dill
@@ -474,10 +476,13 @@ copy("copy_dart2wasm_platform") {
   deps = [
     ":copy_libraries",
     "../:dart2wasm_platform",
+    "../utils/dart2wasm:compile_dart2wasm_js_compatibility_platform",
     "../utils/dart2wasm:compile_dart2wasm_platform",
     "../utils/dart2wasm:compile_dart2wasm_stringref_platform",
   ]
   sources = [
+    "$root_out_dir/dart2wasm_js_compatibility_outline.dill",
+    "$root_out_dir/dart2wasm_js_compatibility_platform.dill",
     "$root_out_dir/dart2wasm_outline.dill",
     "$root_out_dir/dart2wasm_platform.dill",
     "$root_out_dir/dart2wasm_stringref_outline.dill",

sdk/bin/dart2wasm

@@ -65,12 +65,15 @@ SDK_ARG="--dart-sdk=$SDK_DIR"
 
 # Point to built platform dill.
 PLATFORM="$BIN_DIR/dart2wasm_platform.dill"
-# Not the prettiest way to check for stringref, and it doesn't support changing
-# the default, but it will do for the experiment.
+# Not the prettiest way to check for a target, and it doesn't support changing
+# the default, but it will do for experiments.
 for arg in "$@"; do
   if [[ "$arg" == "--stringref" ]]; then
     PLATFORM="$BIN_DIR/dart2wasm_stringref_platform.dill"
   fi
+  if [[ "$arg" == "--js-compatibility" ]]; then
+    PLATFORM="$BIN_DIR/dart2wasm_js_compatibility_platform.dill"
+  fi
 done
 PLATFORM_ARG="--platform=$PLATFORM"
 

sdk/lib/libraries.json

@@ -175,6 +175,34 @@
       }
     }
   },
+  "wasm_js_compatibility": {
+    "include": [
+      {
+        "target": "wasm_common"
+      }
+    ],
+    "libraries": {
+      "core": {
+        "uri": "core/core.dart",
+        "patches": [
+          "_internal/wasm/lib/core_patch.dart",
+          "_internal/vm_shared/lib/array_patch.dart",
+          "_internal/vm_shared/lib/bigint_patch.dart",
+          "_internal/vm_shared/lib/bool_patch.dart",
+          "_internal/vm_shared/lib/date_patch.dart",
+          "_internal/vm_shared/lib/integers_patch.dart",
+          "_internal/vm_shared/lib/map_patch.dart",
+          "_internal/vm_shared/lib/null_patch.dart",
+          "_internal/vm_shared/lib/string_buffer_patch.dart",
+          "_internal/wasm/lib/date_patch_patch.dart",
+          "_internal/wasm/lib/string_buffer_create.dart",
+          "_internal/wasm/lib/string_patch.dart",
+          "_internal/wasm/lib/sync_star_patch.dart",
+          "_internal/wasm/lib/weak_patch.dart"
+        ]
+      }
+    }
+  },
   "wasm_common": {
     "libraries": {
       "_http": {

sdk/lib/libraries.yaml

@@ -156,6 +156,28 @@ wasm_stringref:
       - _internal/wasm/lib/sync_star_patch.dart
       - _internal/wasm/lib/weak_patch.dart
 
+wasm_js_compatibility:
+  include:
+    - target: "wasm_common"
+  libraries:
+    core:
+      uri: core/core.dart
+      patches:
+      - _internal/wasm/lib/core_patch.dart
+      - _internal/vm_shared/lib/array_patch.dart
+      - _internal/vm_shared/lib/bigint_patch.dart
+      - _internal/vm_shared/lib/bool_patch.dart
+      - _internal/vm_shared/lib/date_patch.dart
+      - _internal/vm_shared/lib/integers_patch.dart
+      - _internal/vm_shared/lib/map_patch.dart
+      - _internal/vm_shared/lib/null_patch.dart
+      - _internal/vm_shared/lib/string_buffer_patch.dart
+      - _internal/wasm/lib/date_patch_patch.dart
+      - _internal/wasm/lib/string_buffer_create.dart
+      - _internal/wasm/lib/string_patch.dart
+      - _internal/wasm/lib/sync_star_patch.dart
+      - _internal/wasm/lib/weak_patch.dart
+
 wasm_common:
   libraries:
     _http:

tools/bots/test_matrix.json

@@ -126,6 +126,8 @@
       "out/ReleaseX64/dart2wasm_platform.dill",
       "out/ReleaseX64/dart2wasm_stringref_outline.dill",
       "out/ReleaseX64/dart2wasm_stringref_platform.dill",
+      "out/ReleaseX64/dart2wasm_js_compatibility_outline.dill",
+      "out/ReleaseX64/dart2wasm_js_compatibility_platform.dill",
       "out/ReleaseX64/wasm/",
       "pkg/",
       "runtime/tests/",

utils/dart2wasm/BUILD.gn

@@ -77,6 +77,24 @@ compile_platform("compile_dart2wasm_stringref_platform") {
   ]
 }
 
+compile_platform("compile_dart2wasm_js_compatibility_platform") {
+  single_root_scheme = "org-dartlang-sdk"
+  single_root_base = rebase_path("$sdk_root/")
+  libraries_specification_uri = "org-dartlang-sdk:///lib/libraries.json"
+
+  outputs = [
+    "$root_out_dir/dart2wasm_js_compatibility_platform.dill",
+    "$root_out_dir/dart2wasm_js_compatibility_outline.dill",
+  ]
+
+  args = [
+    "--target=dart2wasm_js_compatibility",
+    "--no-defines",
+    "dart:core",
+    "--nnbd-strong",
+  ]
+}
+
 wasm_module("ffi_native_test_wasm_module") {
   module_name = "ffi_native_test_module"
 }