fix position of duplicating THIS on virtual method calls

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

@@ -0,0 +1,85 @@
+/*
+   Copyright 2019 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 de.inetsoftware.jwebassembly.wasm.AnyType;
+import de.inetsoftware.jwebassembly.wasm.VariableOperator;
+
+/**
+ * This class save a reference of THIS to a temporary variable for a later virtual caLL. The reference of THIS is used for accessing the vtable of the object.
+ * 
+ * @author Volker Berlin
+ */
+class DupThis extends WasmInstruction {
+
+    private WasmCallIndirectInstruction virtualCall;
+
+    private int                         tempVarIdx;
+
+    /**
+     * Create a instance.
+     * 
+     * @param virtualCall
+     *            the related virtual function call.
+     * @param tempVarIdx
+     *            the index of the temporary variable
+     * @param javaCodePos
+     *            the code position
+     */
+    DupThis( WasmCallIndirectInstruction virtualCall, int tempVarIdx, int javaCodePos ) {
+        super( javaCodePos, virtualCall.getLineNumber() );
+        this.virtualCall = virtualCall;
+        this.tempVarIdx = tempVarIdx;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    Type getType() {
+        return Type.DupThis;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    void writeTo( ModuleWriter writer ) throws IOException {
+        if( virtualCall.isVirtual() ) {
+            writer.writeLocal( VariableOperator.tee, tempVarIdx );
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    AnyType getPushValueType() {
+        return null;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    int getPopCount() {
+        return 0;
+    }
+
+}

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

@@ -40,12 +40,7 @@ class WasmCallIndirectInstruction extends WasmCallInstruction {
 
     private final StructType            type;
 
-    /**
+    private int                         tempVarIdx;
-     * the slot of a temporary variable of type "type" to duplicate "this"
-     */
-    private final int                   tempVar;
-
-    private final LocaleVariableManager localVariables;
 
     private final WasmOptions           options;
 
@@ -54,21 +49,18 @@ class WasmCallIndirectInstruction extends WasmCallInstruction {
      * 
      * @param name
      *            the function name that should be called
-     * @param localVariables
-     *            the manager for local variables to translate the Java slot of the temporary variable into wasm local
-     *            position
      * @param javaCodePos
      *            the code position/offset in the Java method
      * @param lineNumber
      *            the line number in the Java source code
      * @param types
      *            the type manager
+     * @param options
+     *            compiler properties
      */
-    WasmCallIndirectInstruction( FunctionName name, LocaleVariableManager localVariables, int javaCodePos, int lineNumber, TypeManager types, WasmOptions options ) {
+    WasmCallIndirectInstruction( FunctionName name, int javaCodePos, int lineNumber, TypeManager types, WasmOptions options ) {
         super( name, javaCodePos, lineNumber, types );
         this.type = types.valueOf( name.className );
-        this.tempVar = localVariables.getTempVariable( type, javaCodePos, javaCodePos + 1 );
-        this.localVariables = localVariables;
         this.options = options;
     }
 
@@ -80,6 +72,23 @@ class WasmCallIndirectInstruction extends WasmCallInstruction {
         return Type.CallIndirect;
     }
 
+    /**
+     * Get the type of this.
+     * 
+     * @return the type
+     */
+    StructType getThisType() {
+        return type;
+    }
+
+    /**
+     * Set the variable index on which this can be found.
+     * @param tempVarIdx the index
+     */
+    void setVariableIndexOfThis( int tempVarIdx ) {
+        this.tempVarIdx = tempVarIdx;
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -89,6 +98,15 @@ class WasmCallIndirectInstruction extends WasmCallInstruction {
         virtualFunctionIdx = functions.getFunctionIndex( getFunctionName() );
     }
 
+    /**
+     * if this call is executed virtual or if is was optimized.
+     * 
+     * @return true, virtual call
+     */
+    boolean isVirtual() {
+        return virtualFunctionIdx > 0;
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -97,10 +115,7 @@ class WasmCallIndirectInstruction extends WasmCallInstruction {
         if( virtualFunctionIdx < 0 ) {
             super.writeTo( writer );
         } else {
-            int tempVarIdx = localVariables.get( tempVar, getCodePosition() );
-
             // duplicate this on the stack
-            writer.writeLocal( VariableOperator.tee, tempVarIdx );
             writer.writeLocal( VariableOperator.get, tempVarIdx );
 
             if( options.useGC() ) {

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

@@ -37,6 +37,7 @@ import de.inetsoftware.jwebassembly.wasm.NumericOperator;
 import de.inetsoftware.jwebassembly.wasm.StructOperator;
 import de.inetsoftware.jwebassembly.wasm.ValueType;
 import de.inetsoftware.jwebassembly.wasm.ValueTypeParser;
+import de.inetsoftware.jwebassembly.wasm.VariableOperator;
 import de.inetsoftware.jwebassembly.wasm.WasmBlockOperator;
 import de.inetsoftware.jwebassembly.wasm.WasmOptions;
 
@@ -104,8 +105,21 @@ public abstract class WasmCodeBuilder {
      *            the count of values on the stack back. 1 means the last value. 2 means the penultimate value.
      * @return the code position that push the last instruction
      */
-    @Nonnull
     int findPushInstructionCodePosition( int count ) {
+        return findPushInstruction( count, true );
+    }
+
+    /**
+     * We need one value from the stack inside of a block. We need to find the WasmInstruction on which the block can
+     * start. If this a function call or numeric expression this can be complex to find the right point.
+     * 
+     * @param count
+     *            the count of values on the stack back. 1 means the last value. 2 means the penultimate value.
+     * @param codePosition
+     *            true, get the code position; false, get the index in the instructions
+     * @return the code position that push the last instruction
+     */
+    private int findPushInstruction( int count, boolean codePosition ) {
         int valueCount = 0;
         List<WasmInstruction> instructions = this.instructions;
         for( int i = instructions.size() - 1; i >= 0; i-- ) {
@@ -116,7 +130,7 @@ public abstract class WasmCodeBuilder {
             }
             valueCount -= instr.getPopCount();
             if( valueCount == count ) {
-                return instr.getCodePosition();
+                return codePosition ? instr.getCodePosition() : i;
             }
         }
         throw new WasmException( "Start position not found", -1 ); // should never occur
@@ -358,7 +372,24 @@ public abstract class WasmCodeBuilder {
      *            the line number in the Java source code
      */
     protected void addCallVirtualInstruction( FunctionName name, int javaCodePos, int lineNumber ) {
-        instructions.add( new WasmCallIndirectInstruction( name, localVariables, javaCodePos, lineNumber, types, options ) );
+        WasmCallIndirectInstruction virtualCall = new WasmCallIndirectInstruction( name, javaCodePos, lineNumber, types, options );
+        int count = virtualCall.getPopCount();
+        int idx = findPushInstruction( count, false );
+        WasmInstruction instr = instructions.get( idx );
+        int varIndex = -1; 
+        if( instr.getType() == Type.Local ) {
+            WasmLocalInstruction local1 = (WasmLocalInstruction)instr;
+            if( local1.getOperator() == VariableOperator.get ) {
+                varIndex = local1.getIndex();
+            }
+        }
+        if( varIndex < 0 ) {
+            varIndex = getTempVariable( virtualCall.getThisType(), instr.getCodePosition(), javaCodePos + 1 );
+            idx = findPushInstruction( count - 1, false );
+            instructions.add( idx, new DupThis( virtualCall, varIndex, javaCodePos ) );
+        }
+        virtualCall.setVariableIndexOfThis( varIndex );
+        instructions.add( virtualCall );
     }
 
     /**

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

@@ -35,7 +35,7 @@ abstract class WasmInstruction {
      * Type of instruction to faster differ as with instanceof.
      */
     static enum Type {
-        Const, Convert, Local, Global, Block, Numeric, Nop, Call, CallIndirect, Array, Struct;
+        Const, Convert, Local, Global, Block, Numeric, Nop, Call, CallIndirect, Array, Struct, DupThis;
     }
 
     private int       javaCodePos;