support the do while(condition) loop

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

@@ -100,14 +100,21 @@ class BranchManger {
      */
     private void addLoops() {
         for( ParsedBlock parsedBlock : allParsedOperations ) {
-            if( parsedBlock.op == JavaBlockOperator.GOTO && parsedBlock.startPosition > parsedBlock.endPosition ) {
+            if( parsedBlock.startPosition > parsedBlock.endPosition ) {
-                int start = parsedBlock.endPosition;
+                switch ( parsedBlock.op ) {
-                ParsedBlock loop = loops.get( start );
+                    case GOTO: // do while(true) loop; Continue
-                if( loop == null ) {
+                    case IF:   // do while(condition) loop
-                    loop = new ParsedBlock( JavaBlockOperator.LOOP, start, 0, parsedBlock.lineNumber );
+                        int start = parsedBlock.endPosition;
-                    loops.put( start, loop );
+                        ParsedBlock loop = loops.get( start );
+                        if( loop == null ) {
+                            loop = new ParsedBlock( JavaBlockOperator.LOOP, start, 0, parsedBlock.lineNumber );
+                            loops.put( start, loop );
+                        }
+                        loop.endPosition = parsedBlock.startPosition + 3;
+                        break;
+                    default:
+                        throw new WasmException( "Unimplemented loop code operation: " + parsedBlock.op, null, parsedBlock.lineNumber );
                 }
-                loop.endPosition = parsedBlock.startPosition + 3;
             }
         }
 
@@ -155,13 +162,19 @@ class BranchManger {
     private void caculateIf( BranchNode parent, ParsedBlock startBlock, List<ParsedBlock> parsedOperations ) {
         int i = 0;
         int endPos = Math.min( startBlock.endPosition, parent.endPos );
+        int startPos = startBlock.startPosition + 3;
+        if( startPos > endPos ) {
+            // the condition in a do while(condition) loop
+            parent.add( new BranchNode( startPos, startPos, WasmBlockOperator.BR_IF, null, 0 ) );
+            return;
+        }
         int gotoPos = endPos - 3; // 3 - byte size of goto instruction
         BranchNode branch = null;
         for( ; i < parsedOperations.size(); i++ ) {
             ParsedBlock parsedBlock = parsedOperations.get( i );
             if( parsedBlock.startPosition == gotoPos && parsedBlock.op == JavaBlockOperator.GOTO && parsedBlock.startPosition < parsedBlock.endPosition) {
                 parsedOperations.remove( i );
-                branch = new BranchNode( startBlock.startPosition, startBlock.endPosition, WasmBlockOperator.IF, null );
+                branch = new BranchNode( startPos, startBlock.endPosition, WasmBlockOperator.IF, null );
                 parent.add( branch );
                 if( i > 0 ) {
                     calculate( branch, parsedOperations.subList( 0, i ) );
@@ -177,7 +190,7 @@ class BranchManger {
         }
 
         if( branch == null ) {
-            branch = new BranchNode( startBlock.startPosition, endPos, WasmBlockOperator.IF, WasmBlockOperator.END );
+            branch = new BranchNode( startPos, endPos, WasmBlockOperator.IF, WasmBlockOperator.END );
             parent.add( branch );
         }
 

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

@@ -466,7 +466,7 @@ public class ModuleGenerator {
                     case 165: // if_acmpeq
                     case 166: // if_acmpne
                         int offset = byteCode.readShort();
-                        branchManager.start( JavaBlockOperator.IF, codePosition + 3, offset - 3, lineNumber );
+                        branchManager.start( JavaBlockOperator.IF, codePosition, offset, lineNumber );
                         break;
                     case 167: // goto
                         offset = byteCode.readShort();
@@ -864,40 +864,40 @@ public class ModuleGenerator {
                         opCompare( ValueType.f64, byteCode );
                         break;
                     case 153: // ifeq
-                        opIfCondition( NumericOperator.ne, byteCode );
+                        opIfCondition( NumericOperator.ne, NumericOperator.eq, byteCode );
                         break;
                     case 154: // ifne
-                        opIfCondition( NumericOperator.eq, byteCode );
+                        opIfCondition( NumericOperator.eq, NumericOperator.ne, byteCode );
                         break;
                     case 155: // iflt
-                        opIfCondition( NumericOperator.ge_s, byteCode );
+                        opIfCondition( NumericOperator.ge_s, NumericOperator.lt_s, byteCode );
                         break;
                     case 156: // ifge
-                        opIfCondition( NumericOperator.lt_s, byteCode );
+                        opIfCondition( NumericOperator.lt_s, NumericOperator.ge_s, byteCode );
                         break;
                     case 157: // ifgt
-                        opIfCondition( NumericOperator.le_s, byteCode );
+                        opIfCondition( NumericOperator.le_s, NumericOperator.gt, byteCode );
                         break;
                     case 158: // ifle
-                        opIfCondition( NumericOperator.gt, byteCode );
+                        opIfCondition( NumericOperator.gt, NumericOperator.le_s, byteCode );
                         break;
                     case 159: // if_icmpeq
-                        opIfCompareCondition( NumericOperator.ne, byteCode );
+                        opIfCompareCondition( NumericOperator.ne, NumericOperator.eq, byteCode );
                         break;
                     case 160: // if_icmpne
-                        opIfCompareCondition( NumericOperator.eq, byteCode );
+                        opIfCompareCondition( NumericOperator.eq, NumericOperator.ne, byteCode );
                         break;
                     case 161: // if_icmplt
-                        opIfCompareCondition( NumericOperator.ge_s, byteCode );
+                        opIfCompareCondition( NumericOperator.ge_s, NumericOperator.lt_s, byteCode );
                         break;
                     case 162: // if_icmpge
-                        opIfCompareCondition( NumericOperator.lt_s, byteCode );
+                        opIfCompareCondition( NumericOperator.lt_s, NumericOperator.ge_s, byteCode );
                         break;
                     case 163: // if_icmpgt
-                        opIfCompareCondition( NumericOperator.le_s, byteCode );
+                        opIfCompareCondition( NumericOperator.le_s, NumericOperator.gt, byteCode );
                         break;
                     case 164: // if_icmple
-                        opIfCompareCondition( NumericOperator.gt, byteCode );
+                        opIfCompareCondition( NumericOperator.gt, NumericOperator.le_s, byteCode );
                         break;
                     //TODO case 165: // if_acmpeq
                     //TODO case 166: // if_acmpne
@@ -1029,37 +1029,40 @@ public class ModuleGenerator {
 
     /**
      * Handle the if<condition> of the Java byte code. This Java instruction compare the first stack value with value 0.
-     * Important: In Java the condition for the jump to the else block is saved. In WebAssembler we need to use
+     * Important: In the Java IF expression the condition for the jump to the else block is saved. In WebAssembler we need to use
      * condition for the if block. The caller of the method must already negate this
      * 
-     * @param numOp
+     * @param ifNumOp
-     *            The condition for the if block.
-     * @param byteCode
-     *            current byte code stream to read the taget offset.
-     * @throws IOException
-     *             if any I/O errors occur.
-     */
-    private void opIfCondition( NumericOperator numOp, CodeInputStream byteCode ) throws IOException {
-        byteCode.skip(2);
-        writer.writeConstInt( 0 );
-        writer.writeNumericOperator( numOp, ValueType.i32 );
-    }
-
-    /**
-     * Handle the if<condition> of the Java byte code. This Java instruction compare the first stack value with value 0.
-     * Important: In Java the condition for the jump to the else block is saved. In WebAssembler we need to use
-     * condition for the if block. The caller of the method must already negate this
-     * 
-     * @param numOp
      *            The condition for the if block.
+     * @param continueNumOp
+     *            The condition for the continue of a loop.
      * @param byteCode
      *            current byte code stream to read the target offset.
      * @throws IOException
      *             if any I/O errors occur.
      */
-    private void opIfCompareCondition( NumericOperator numOp, CodeInputStream byteCode ) throws IOException {
+    private void opIfCondition( NumericOperator ifNumOp, NumericOperator continueNumOp, CodeInputStream byteCode ) throws IOException {
-        byteCode.skip(2);
+        writer.writeConstInt( 0 );
-        writer.writeNumericOperator( numOp, ValueType.i32 );
+        opIfCompareCondition( ifNumOp, continueNumOp, byteCode );
+    }
+
+    /**
+     * Handle the if<condition> of the Java byte code. This Java instruction compare 2 values from stack.
+     * Important: In the Java IF expression the condition for the jump to the else block is saved. In WebAssembler we need to use
+     * condition for the if block. The caller of the method must already negate this.
+     * 
+     * @param ifNumOp
+     *            The condition for the if block.
+     * @param continueNumOp
+     *            The condition for the continue of a loop.
+     * @param byteCode
+     *            current byte code stream to read the target offset.
+     * @throws IOException
+     *             if any I/O errors occur.
+     */
+    private void opIfCompareCondition( NumericOperator ifNumOp, NumericOperator continueNumOp, CodeInputStream byteCode ) throws IOException {
+        int offset = byteCode.readShort();
+        writer.writeNumericOperator( offset > 0 ? ifNumOp : continueNumOp, ValueType.i32 );
     }
 
     /**

test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java

@@ -46,6 +46,7 @@ public class ControlFlowOperators extends AbstractBaseTest {
             addParam( list, script, "ifCompare" );
             addParam( list, script, "switchDirect" );
             addParam( list, script, "endlessLoop" );
+            addParam( list, script, "doWhileLoop" );
             addParam( list, script, "forLoop" );
         }
         return list;
@@ -198,6 +199,17 @@ public class ControlFlowOperators extends AbstractBaseTest {
             } while( true );
         }
 
+        @Export
+        static double doWhileLoop() {
+            int a = 0;
+            double d = 1.01;
+            do {
+                d *= 2;
+                a++;
+            } while( a < 10 );
+            return d;
+        }
+
         @Export
         static int forLoop() {
             int a = 0;