Add support for global (static) variables

Author: Volker

src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java

@@ -26,6 +26,7 @@
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import de.inetsoftware.classparser.ConstantRef;
 import de.inetsoftware.jwebassembly.WasmException;
 import de.inetsoftware.jwebassembly.module.FunctionName;
 import de.inetsoftware.jwebassembly.module.ModuleWriter;
@@ -387,6 +388,24 @@ protected void writeStore( int idx ) throws IOException {
         codeStream.writeVaruint32( idx );
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    protected void writeGlobalAccess( boolean load, FunctionName name, ConstantRef ref ) throws IOException {
+        Global var = globals.get( name.fullName );
+        if( var == null ) { // if not declared then create a definition in the global section
+            var = new Global();
+            var.id = globals.size();
+            var.type = ValueType.getValueType( ref.getType(), 0 );
+            var.mutability = true;
+            globals.put( name.fullName, var );
+        }
+        int op = load ? GET_GLOBAL : SET_GLOBAL;
+        codeStream.writeOpCode( op );
+        codeStream.writeVaruint32( var.id );
+    }
+
     /**
      * {@inheritDoc}
      */

src/de/inetsoftware/jwebassembly/binary/Global.java

@@ -24,6 +24,8 @@
  */
 class Global {
 
+    int id;
+
     ValueType type;
 
     boolean mutability;

src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java

@@ -648,8 +648,14 @@ private void writeCode( CodeInputStream byteCode, ConstantPool constantPool  ) t
                         instr = new WasmBlockInstruction( WasmBlockOperator.RETURN, type, codePos );
                         endWithReturn = true;
                         break;
-                    //TODO case 178: // getstatic
-                    //TODO case 179: // putstatic
+                    case 178: // getstatic
+                        ConstantRef ref = (ConstantRef)constantPool.get( byteCode.readUnsignedShort() );
+                        instr = new WasmGlobalInstruction( true, ref, codePos );
+                        break;
+                    case 179: // putstatic
+                        ref = (ConstantRef)constantPool.get( byteCode.readUnsignedShort() );
+                        instr = new WasmGlobalInstruction( false, ref, codePos );
+                        break;
                     //TODO case 180: // getfield
                     //TODO case 181: // putfield
                     //TODO case 182: // invokevirtual

src/de/inetsoftware/jwebassembly/module/ModuleWriter.java

@@ -22,6 +22,8 @@
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import de.inetsoftware.classparser.ConstantRef;
+
 /**
  * Module Writer base class.
  * 
@@ -144,6 +146,21 @@ protected void prepareFunction( FunctionName name ) {}
      */
     protected abstract void writeStore( int idx ) throws IOException;
 
+    /**
+     * Write a set_global variable
+     * @param load
+     *            true: if load or GET
+     * @param name
+     *            the variable name
+     * @param ref
+     *            the definition of the variable
+     * 
+     * @throws IOException
+     *             if any I/O error occur
+     */
+    protected abstract void writeGlobalAccess( boolean load, FunctionName name, ConstantRef ref ) throws IOException;
+
+
     /**
      * Write a add operator
      * 

src/de/inetsoftware/jwebassembly/module/WasmGlobalInstruction.java

@@ -0,0 +1,75 @@
+/*
+   Copyright 2018 Volker Berlin (i-net software)
+
+   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
+
+       http://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 de.inetsoftware.jwebassembly.module;
+
+import java.io.IOException;
+
+import javax.annotation.Nonnull;
+
+import de.inetsoftware.classparser.ConstantRef;
+
+/**
+ * WasmInstruction for set and get global variables.
+ * 
+ * @author Volker Berlin
+ *
+ */
+class WasmGlobalInstruction extends WasmInstruction {
+
+    private boolean     load;
+
+    private ConstantRef ref;
+
+    /**
+     * Create an instance of a load/store instruction
+     * 
+     * @param load
+     *            true: if load or GET
+     * @param ref
+     *            reference to a static field
+     * @param javaCodePos
+     *            the code position/offset in the Java method
+     */
+    WasmGlobalInstruction( boolean load, ConstantRef ref, int javaCodePos ) {
+        super( javaCodePos );
+        this.load = load;
+        this.ref = ref;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public void writeTo( @Nonnull ModuleWriter writer ) throws IOException {
+        FunctionName name = new FunctionName( ref );
+        writer.writeGlobalAccess( load, name, ref );
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    ValueType getPushValueType() {
+        return load ? ValueType.getValueType( ref.getType(), 0 ) : null;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    int getPopCount() {
+        return load ? 0 : 1;
+    }
+}

src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java

@@ -16,11 +16,13 @@
 package de.inetsoftware.jwebassembly.text;
 
 import java.io.IOException;
+import java.util.HashSet;
 import java.util.List;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import de.inetsoftware.classparser.ConstantRef;
 import de.inetsoftware.jwebassembly.module.FunctionName;
 import de.inetsoftware.jwebassembly.module.ModuleWriter;
 import de.inetsoftware.jwebassembly.module.NumericOperator;
@@ -36,11 +38,13 @@
  */
 public class TextModuleWriter extends ModuleWriter {
 
-    private Appendable output;
+    private Appendable      output;
 
-    private StringBuilder methodOutput = new StringBuilder();
+    private StringBuilder   methodOutput = new StringBuilder();
 
-    private int        inset;
+    private int             inset;
+
+    private HashSet<String> globals      = new HashSet<>();
 
     /**
      * Create a new instance.
@@ -153,6 +157,22 @@ protected void writeStore( int idx ) throws IOException {
         methodOutput.append( "set_local " ).append( Integer.toString( idx ) );
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    protected void writeGlobalAccess( boolean load, FunctionName name, ConstantRef ref ) throws IOException {
+        if( !globals.contains( name.fullName ) ) {
+            // declare global variable if not already declared.
+            output.append( "\n  " );
+            String type = ValueType.getValueType( ref.getType(), 0 ).toString();
+            output.append( "(global $" ).append( name.fullName ).append( type ).append( ' ' ).append( type ).append( ".const 0)" );
+            globals.add( name.fullName );
+        }
+        newline( methodOutput );
+        methodOutput.append( load ? "get_local " : "set_local " ).append( name.fullName );
+    }
+
     /**
      * {@inheritDoc}
      */