[WASM] Start emitting a summary for modular compilation.

This initial summary contains type - supertype relationships that will be used to synthesize itables in the bundler.

PiperOrigin-RevId: 572957936

transpiler/java/com/google/j2cl/common/OutputUtils.java

@@ -48,6 +48,11 @@ private Output(Problems problems, Path root) {
       this.root = root;
     }
 
+    public void write(String path, byte[] content) {
+      Path outputPath = root.resolve(path);
+      fileService.execute(() -> OutputUtils.writeToFile(outputPath, content, problems));
+    }
+
     public void write(String path, String content) {
       Path outputPath = root.resolve(path);
       fileService.execute(() -> OutputUtils.writeToFile(outputPath, content, problems));

transpiler/java/com/google/j2cl/transpiler/backend/wasm/BUILD

@@ -1,17 +1,32 @@
 package(
     default_applicable_licenses = ["//:j2cl_license"],
-    default_visibility = ["//transpiler:__subpackages__"],
+    default_visibility = [
+        "//tools:__subpackages__",
+        "//transpiler:__subpackages__",
+    ],
     licenses = ["notice"],
 )
 
+proto_library(
+    name = "summary_proto",
+    srcs = ["summary.proto"],
+)
+
+java_proto_library(
+    name = "summary_java_proto",
+    deps = [":summary_proto"],
+)
+
 java_library(
     name = "wasm",
     srcs = glob(["*.java"]),
     deps = [
+        ":summary_java_proto",
         "//third_party:auto_value",
         "//third_party:gson",
         "//third_party:guava",
         "//third_party:jsr305_annotations",
+        "//third_party:protobuf_util_json",
         "//transpiler/java/com/google/j2cl/common",
         "//transpiler/java/com/google/j2cl/transpiler/ast",
         "//transpiler/java/com/google/j2cl/transpiler/backend/closure",

transpiler/java/com/google/j2cl/transpiler/backend/wasm/SummaryBuilder.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2023 Google Inc.
+ *
+ * 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
+ *
+ *     https://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.
+ */
+package com.google.j2cl.transpiler.backend.wasm;
+
+import static java.util.function.Predicate.not;
+
+import com.google.j2cl.common.Problems;
+import com.google.j2cl.common.Problems.FatalError;
+import com.google.j2cl.transpiler.ast.DeclaredTypeDescriptor;
+import com.google.j2cl.transpiler.ast.Library;
+import com.google.j2cl.transpiler.ast.Type;
+import com.google.protobuf.util.JsonFormat;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import javax.annotation.Nullable;
+
+/** Summarizes information where global knowledge will be required for bundling. */
+public final class SummaryBuilder {
+
+  public static final int NULL_TYPE = 0;
+
+  private final Summary.Builder summary = Summary.newBuilder();
+  private final Map<String, Integer> types = new HashMap<>();
+  private final Map<String, Integer> declaredTypes = new HashMap<>();
+
+  private final WasmGenerationEnvironment environment;
+
+  SummaryBuilder(Library library, WasmGenerationEnvironment environment, Problems problems) {
+    this.environment = environment;
+
+    library.streamTypes().forEach(this::addType);
+  }
+
+  private void addType(Type type) {
+    if (type.isInterface()) {
+      return;
+    }
+
+    int typeId = getDeclaredTypeId(type.getTypeDescriptor());
+
+    TypeHierarchyInfo.Builder typeHierarchyInfoBuilder =
+        TypeHierarchyInfo.newBuilder().setDeclaredTypeId(typeId);
+
+    DeclaredTypeDescriptor superTypeDescriptor = type.getSuperTypeDescriptor();
+    if (superTypeDescriptor != null && !superTypeDescriptor.isNative()) {
+      typeHierarchyInfoBuilder.setExtendsDeclaredTypeId(getDeclaredTypeId(superTypeDescriptor));
+    }
+
+    type.getSuperInterfaceTypeDescriptors().stream()
+        .filter(not(DeclaredTypeDescriptor::isNative))
+        .filter(not(DeclaredTypeDescriptor::isJsFunctionInterface))
+        .forEach(t -> typeHierarchyInfoBuilder.addImplementsDeclaredTypeId(getDeclaredTypeId(t)));
+
+    summary.addType(typeHierarchyInfoBuilder.build());
+  }
+
+  private int getDeclaredTypeId(DeclaredTypeDescriptor typeDescriptor) {
+    String typeName = environment.getTypeSignature(typeDescriptor);
+    // Note that the IDs start from '1' to reserve '0' for NULL_TYPE.
+    return declaredTypes.computeIfAbsent(typeName, x -> declaredTypes.size() + 1);
+  }
+
+  private Summary build() {
+    summary.clearTypeReferenceMap();
+    String[] typeReferenceMap = new String[types.size()];
+    types.forEach((name, i) -> typeReferenceMap[i] = name);
+    summary.addAllTypeReferenceMap(Arrays.asList(typeReferenceMap));
+    String[] declaredTypeMap = new String[declaredTypes.size() + 1];
+    // Add a spurious mapping for 0 for the cases where the type is absent, e.g. the supertype
+    // of java.lang.Object.
+    declaredTypeMap[NULL_TYPE] = "<no-type>";
+    declaredTypes.forEach((name, i) -> declaredTypeMap[i] = name);
+    summary.addAllDeclaredTypeMap(Arrays.asList(declaredTypeMap));
+    return summary.build();
+  }
+
+  /** Serialize a LibraryInfo object into a JSON string. */
+  @Nullable
+  public String toJson(Problems problems) {
+    try {
+      return JsonFormat.printer().print(build());
+    } catch (IOException e) {
+      problems.fatal(FatalError.CANNOT_WRITE_FILE, e.toString());
+      return null;
+    }
+  }
+
+  public byte[] toByteArray() {
+    return build().toByteArray();
+  }
+}

transpiler/java/com/google/j2cl/transpiler/backend/wasm/WasmGenerationEnvironment.java

@@ -162,7 +162,7 @@ String getWasmTypeName(TypeDescriptor typeDescriptor) {
     return getTypeSignature(typeDescriptor);
   }
 
-  private static String getTypeSignature(TypeDescriptor typeDescriptor) {
+  public String getTypeSignature(TypeDescriptor typeDescriptor) {
     if (typeDescriptor.isPrimitive()) {
       return "$" + typeDescriptor.getReadableDescription();
     }

transpiler/java/com/google/j2cl/transpiler/backend/wasm/WasmOutputsGenerator.java

@@ -76,13 +76,20 @@ public WasmOutputsGenerator(Output output, Path libraryInfoOutputPath, Problems
   }
 
   public void generateModularOutput(Library library) {
-    // TODO(b/283154838): Add the modular summaries and the library info output.
     if (libraryInfoOutputPath != null) {
       OutputUtils.writeToFile(libraryInfoOutputPath, new byte[0], problems);
     }
+
     environment =
         new WasmGenerationEnvironment(
             library, JsImportsGenerator.collectImports(library, problems));
+    SummaryBuilder summaryBuilder = new SummaryBuilder(library, environment, problems);
+
+    // TODO(rluble): Introduce/use flags to emit the readable version of the summary. For now emit
+    // summaries in both binary and text form for now.
+    output.write("summary.txtpb", summaryBuilder.toJson(problems));
+    output.write("summary.binpb", summaryBuilder.toByteArray());
+
     List<ArrayTypeDescriptor> usedNativeArrayTypes = collectUsedNativeArrayTypes(library);
 
     copyJavaSources(library);

transpiler/java/com/google/j2cl/transpiler/backend/wasm/summary.proto

@@ -0,0 +1,18 @@
+syntax = "proto3";
+
+package j2cl;
+
+option java_multiple_files = true;
+option java_package = "com.google.j2cl.transpiler.backend.wasm";
+
+message Summary {
+  repeated string declared_type_map = 1;
+  repeated string type_reference_map = 2;
+  repeated TypeHierarchyInfo type = 3;
+}
+
+message TypeHierarchyInfo {
+  int32 declared_type_id = 1;
+  int32 extends_declared_type_id = 2;
+  repeated int32 implements_declared_type_id = 3;
+}

transpiler/javatests/com/google/j2cl/readable/java/emptymethod/output_wasm_modular/summary.txtpb.txt

@@ -0,0 +1,7 @@
+{
+  "declaredTypeMap": ["\u003cno-type\u003e", "$emptymethod.EmptyMethod", "$java.lang.Object"],
+  "type": [{
+    "declaredTypeId": 1,
+    "extendsDeclaredTypeId": 2
+  }]
+}

transpiler/javatests/com/google/j2cl/readable/java/interfaces/output_wasm_modular/summary.txtpb.txt

@@ -0,0 +1,15 @@
+{
+  "declaredTypeMap": ["\u003cno-type\u003e", "$interfaces.Main", "$java.lang.Object", "$interfaces.Main.Implementor", "$interfaces.Main.SubInterface", "$interfaces.Main.Interface", "$interfaces.Main.AbstractImplementor"],
+  "type": [{
+    "declaredTypeId": 1,
+    "extendsDeclaredTypeId": 2
+  }, {
+    "declaredTypeId": 3,
+    "extendsDeclaredTypeId": 2,
+    "implementsDeclaredTypeId": [4, 5]
+  }, {
+    "declaredTypeId": 6,
+    "extendsDeclaredTypeId": 2,
+    "implementsDeclaredTypeId": [4]
+  }]
+}

transpiler/javatests/com/google/j2cl/readable/readable_example.bzl

@@ -12,7 +12,6 @@ readable_example(
 
 """
 
-load("@io_bazel_rules_closure//closure:defs.bzl", "js_binary")
 load("@bazel_skylib//rules:write_file.bzl", "write_file")
 load(
     "//build_defs:rules.bzl",
@@ -23,6 +22,7 @@ load(
 )
 load("@bazel_tools//tools/build_defs/apple:ios.bzl", "ios_build_test")
 load("@bazel_skylib//rules:build_test.bzl", "build_test")
+load("@io_bazel_rules_closure//closure:defs.bzl", "js_binary")
 
 JAVAC_FLAGS = [
     "-XepDisableAllChecks",
@@ -57,6 +57,7 @@ def readable_example(
       javacopts: javacopts to apply j2cl_library
       **kwargs: passes to j2cl_library
     """
+
     readable_source_maps = True
     if any([src for src in srcs if src.endswith(".kt")]):
         # J2KT doesn't make sense for Kotlin Frontend.
@@ -235,7 +236,7 @@ def _golden_output_impl(ctx):
     readable_name = ctx.label.package.rsplit("/", 1)[1]
 
     if input.is_directory:
-        excluded_extensions = ["java", "map"]
+        excluded_extensions = ["java", "map", "binpb"]
 
         # We exclude kotlin files only if they are not generated by the transpiler (J2KT).
         # 'input' is the output tree artifact of the transpiler.