[vm] Adding static_field_offset to Field objects.

This adds the offset of static fields within their field table.

TEST=vm/dart/analyze_snapshot_binary_test

Change-Id: I90b13760fa3203ca2e3c5611e3fd890a74c97728
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/429880
Reviewed-by: Martin Kustermann <[email protected]>
Commit-Queue: Martin Kustermann <[email protected]>

Author: Roy

runtime/tests/vm/dart/analyze_snapshot_binary_test.dart

@@ -16,6 +16,7 @@ import 'use_flag_test_helper.dart';
 const int headerSize = 8;
 final int compressedWordSize =
     sizeOf<Pointer>() == 8 && !Platform.executable.contains('64C') ? 8 : 4;
+const int wordSize = 8; // analyze_snapshot is not supported on arm32
 
 // Used to ensure we don't have multiple equivalent calls to test.
 final _seenDescriptions = <String>{};
@@ -222,7 +223,8 @@ Future<void> testAOT(
 
     // We have:
     //   class Base {
-    //     static int baseS = int.parse('1');
+    //     static int baseS0 = int.parse('1');
+    //     static int baseS1 = int.parse('2');
     //     int base0;
     //     double base1;
     //     Object? base2;
@@ -231,10 +233,17 @@ Future<void> testAOT(
     //   }
     //
     // This static field is never tree shaken.
-    expectField(baseFields[0], name: 'baseS', flags: ['static']);
+    expectField(baseFields[0], name: 'baseS0', flags: ['static']);
+    expectField(baseFields[1], name: 'baseS1', flags: ['static']);
+
+    // Neighboring static fields should always be one word away
+    final int staticFieldOffset0 = baseFields[0]["static_field_offset"];
+    final int staticFieldOffset1 = baseFields[1]["static_field_offset"];
+    Expect.equals(staticFieldOffset1 - staticFieldOffset0, wordSize);
+
     if (isProduct) {
       // Most [Field] objests are tree shaken.
-      Expect.equals(1, baseFields.length);
+      Expect.equals(2, baseFields.length);
 
       int slotOffset = 0;
       slotOffset += expectUnknown8Bytes(
@@ -264,28 +273,28 @@ Future<void> testAOT(
       );
     } else {
       // We don't tree shake [Field] objects in non-product builds.
-      Expect.equals(6, baseFields.length);
+      Expect.equals(7, baseFields.length);
       expectField(
-        baseFields[1],
+        baseFields[2],
         name: 'base0',
         isReference: false,
         unboxedType: 'int',
       );
       expectField(
-        baseFields[2],
+        baseFields[3],
         name: 'base1',
         isReference: false,
         unboxedType: 'double',
       );
-      expectField(baseFields[3], name: 'base2');
+      expectField(baseFields[4], name: 'base2');
       expectField(
-        baseFields[4],
+        baseFields[5],
         name: 'base3',
         isReference: false,
         unboxedType: 'Float32x4',
       );
       expectField(
-        baseFields[5],
+        baseFields[6],
         name: 'base4',
         isReference: false,
         unboxedType: 'Float64x2',
@@ -296,34 +305,34 @@ Future<void> testAOT(
         offsetReferences: 0,
         offsetBytes: 0,
         isReference: false,
-        fieldId: baseFieldIds[1],
+        fieldId: baseFieldIds[2],
       );
       slotOffset += expectInstanceSlot(
         baseSlots[slotOffset],
         offsetReferences: 0,
         offsetBytes: 8,
         isReference: false,
-        fieldId: baseFieldIds[2],
+        fieldId: baseFieldIds[3],
       );
       slotOffset += expectInstanceSlot(
         baseSlots[slotOffset],
         offsetReferences: 0,
         offsetBytes: 16,
-        fieldId: baseFieldIds[3],
+        fieldId: baseFieldIds[4],
       );
       slotOffset += expectInstanceSlot(
         baseSlots[slotOffset],
         offsetReferences: 1,
         offsetBytes: 16,
         isReference: false,
-        fieldId: baseFieldIds[4],
+        fieldId: baseFieldIds[5],
       );
       slotOffset += expectInstanceSlot(
         baseSlots[slotOffset],
         offsetReferences: 1,
         offsetBytes: 32,
         isReference: false,
-        fieldId: baseFieldIds[5],
+        fieldId: baseFieldIds[6],
       );
     }
     // We have:

runtime/tests/vm/dart/analyze_snapshot_program.dart

@@ -40,18 +40,21 @@ main() {
 }
 
 class FieldTestBase {
-  static int baseS = int.parse('1');
+  static int baseS0 = int.parse('1');
+  static int baseS1 = int.parse('2');
   int base0;
   double base1;
   Object? base2;
   Float32x4 base3;
   Float64x2 base4;
 
   FieldTestBase(this.base0, this.base1, this.base2, this.base3, this.base4) {
-    baseS++;
+    baseS0++;
+    baseS1++;
   }
 
-  String foo() => 'Base.foo: [$baseS, $base0, $base1, $base2, $base3, $base4]';
+  String foo() =>
+      'Base.foo: [$baseS0, $baseS1, $base0, $base1, $base2, $base3, $base4]';
 }
 
 class FieldTestSub<T> extends FieldTestBase {

runtime/vm/analyze_snapshot_api_impl.cc

@@ -293,6 +293,8 @@ void SnapshotAnalyzer::DumpField(const Field& field) {
   js_.PrintProperty64("type_class", GetObjectId(field.type()));
   if (field.is_static()) {
     js_.PrintProperty("instance", GetObjectId(field.StaticValue()));
+    js_.PrintProperty64("static_field_offset",
+                        FieldTable::FieldOffsetFor(field.field_id()));
   }
   if (field.HasInitializerFunction()) {
     js_.PrintProperty("initializer_function",