From f7296e038981fac81f0c9932b2dc27fe385c7054 Mon Sep 17 00:00:00 2001
From: Alexey Andreev <Alexey.Andreev@jetbrains.com>
Date: Thu, 8 Sep 2016 14:47:48 +0300
Subject: [PATCH] Add static GC roots

---
 .../wasm/generate/WasmClassGenerator.java     | 34 +++++++++++++++++--
 .../java/org/teavm/runtime/Allocator.java     |  4 ++-
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/core/src/main/java/org/teavm/backend/wasm/generate/WasmClassGenerator.java b/core/src/main/java/org/teavm/backend/wasm/generate/WasmClassGenerator.java
index 0893ccc6d..91dfcc077 100644
--- a/core/src/main/java/org/teavm/backend/wasm/generate/WasmClassGenerator.java
+++ b/core/src/main/java/org/teavm/backend/wasm/generate/WasmClassGenerator.java
@@ -30,6 +30,7 @@ import org.teavm.backend.wasm.binary.DataPrimitives;
 import org.teavm.backend.wasm.binary.DataStructure;
 import org.teavm.backend.wasm.binary.DataType;
 import org.teavm.backend.wasm.binary.DataValue;
+import org.teavm.common.IntegerArray;
 import org.teavm.interop.Address;
 import org.teavm.interop.Function;
 import org.teavm.interop.Structure;
@@ -70,6 +71,8 @@ public class WasmClassGenerator {
             DataPrimitives.INT, /* isInstance function */
             DataPrimitives.ADDRESS, /* parent */
             DataPrimitives.ADDRESS  /* layout */);
+    private IntegerArray staticGcRoots = new IntegerArray(1);
+    private int staticGcRootsAddress;
 
     private static final int CLASS_SIZE = 1;
     private static final int CLASS_FLAGS = 2;
@@ -203,10 +206,9 @@ public class WasmClassGenerator {
 
         List<FieldReference> fields = getReferenceFields(binaryData.cls);
         if (!fields.isEmpty()) {
-            header.setAddress(CLASS_LAYOUT, binaryWriter.getAddress());
             DataValue layoutSize = DataPrimitives.SHORT.createValue();
             layoutSize.setShort(0, (short) fields.size());
-            binaryWriter.append(layoutSize);
+            header.setAddress(CLASS_LAYOUT, binaryWriter.append(layoutSize));
             for (FieldReference field : fields) {
                 DataValue layoutElement = DataPrimitives.SHORT.createValue();
                 layoutElement.setShort(0, (short) binaryData.fieldLayout.get(field.getFieldName()));
@@ -214,6 +216,10 @@ public class WasmClassGenerator {
             }
         }
 
+        for (FieldReference field : getStaticReferenceFields(binaryData.cls)) {
+            staticGcRoots.add(binaryData.fieldLayout.get(field.getFieldName()));
+        }
+
         return vtable != null ? wrapper : header;
     }
 
@@ -225,6 +231,14 @@ public class WasmClassGenerator {
                 .collect(Collectors.toList());
     }
 
+    private List<FieldReference> getStaticReferenceFields(ClassReader cls) {
+        return cls.getFields().stream()
+                .filter(field -> field.hasModifier(ElementModifier.STATIC))
+                .filter(field -> !(field.getType() instanceof ValueType.Primitive))
+                .map(field -> field.getReference())
+                .collect(Collectors.toList());
+    }
+
     private void fillVirtualTable(VirtualTable vtable, DataValue array) {
         int index = 0;
         for (VirtualTableEntry vtableEntry : vtable.getEntries().values()) {
@@ -392,6 +406,22 @@ public class WasmClassGenerator {
                 }
             }
         }
+        writeStaticGcRoots();
+    }
+
+    public int getStaticGcRootsAddress() {
+        return staticGcRootsAddress;
+    }
+
+    private void writeStaticGcRoots() {
+        DataValue sizeValue = DataPrimitives.LONG.createValue();
+        sizeValue.setLong(0, staticGcRoots.size());
+        staticGcRootsAddress = binaryWriter.append(sizeValue);
+        for (int gcRoot : staticGcRoots.getAll()) {
+            DataValue value = DataPrimitives.ADDRESS.createValue();
+            value.setAddress(0, gcRoot);
+            binaryWriter.append(value);
+        }
     }
 
     public boolean hasClinit(String className) {
diff --git a/core/src/main/java/org/teavm/runtime/Allocator.java b/core/src/main/java/org/teavm/runtime/Allocator.java
index 19d485328..924b71b53 100644
--- a/core/src/main/java/org/teavm/runtime/Allocator.java
+++ b/core/src/main/java/org/teavm/runtime/Allocator.java
@@ -24,7 +24,7 @@ public final class Allocator {
     private Allocator() {
     }
 
-    private static Address address = initialize();
+    static Address address = initialize();
 
     private static native Address initialize();
 
@@ -64,4 +64,6 @@ public final class Allocator {
     public static native void removeGcRoot(int index);
 
     public static native void releaseStack(int size);
+
+    public static native Address getStaticGcRoots();
 }