From f15fb1cdf9eab2cc460f046ac873cffaa4a642d1 Mon Sep 17 00:00:00 2001
From: Volker Berlin <volker.berlin@googlemail.com>
Date: Sat, 25 Apr 2020 19:31:30 +0200
Subject: [PATCH] implements dup_x1 instruction

---
 .../module/JavaMethodWasmCodeBuilder.java     |  4 ++-
 .../jwebassembly/module/WasmCodeBuilder.java  | 27 +++++++++++++++++++
 .../jwebassembly/runtime/StructsGC.java       |  5 ++--
 .../jwebassembly/runtime/StructsNonGC.java    |  6 ++---
 4 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java b/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
index 32cb25a..e03c4cc 100644
--- a/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
+++ b/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
@@ -306,8 +306,10 @@ class JavaMethodWasmCodeBuilder extends WasmCodeBuilder {
                         addDupInstruction( codePos, lineNumber );
                         break;
                     case 90: // dup_x1
-                    case 91: // dup_x2
                     case 93: // dup2_x1
+                        addDupX1Instruction( codePos, lineNumber );
+                        break;
+                    case 91: // dup_x2
                     case 94: // dup2_x2
                     case 95: // swap
                         // can be do with functions with more as one return value in future WASM standard
diff --git a/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java b/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
index 5db6f8c..3af6158 100644
--- a/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
+++ b/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
@@ -333,6 +333,33 @@ public abstract class WasmCodeBuilder {
         }
     }
 
+    /**
+     * Simulate the dup_x1 Java byte code instruction.<p>
+     * 
+     * ..., value2, value1 → ..., value1, value2, value1
+     * 
+     * @param javaCodePos
+     *            the code position/offset in the Java method
+     * @param lineNumber
+     *            the line number in the Java source code
+     */
+    protected void addDupX1Instruction( int javaCodePos, int lineNumber ) {
+        AnyType type1 = findValueTypeFromStack( 1, javaCodePos );
+        AnyType type2 = findValueTypeFromStack( 2, javaCodePos );
+
+        int varIndex1 = getTempVariable( type1, javaCodePos, javaCodePos + 1 );
+        int varIndex2 = getTempVariable( type2, javaCodePos, javaCodePos + 1 );;
+
+        // save in temp variables
+        instructions.add( new WasmLocalInstruction( VariableOperator.set, varIndex1, localVariables, javaCodePos, lineNumber ) );
+        instructions.add( new WasmLocalInstruction( VariableOperator.set, varIndex2, localVariables, javaCodePos, lineNumber ) );
+
+        // and restore it in new order on the stack
+        instructions.add( new WasmLocalInstruction( VariableOperator.get, varIndex1, localVariables, javaCodePos, lineNumber ) );
+        instructions.add( new WasmLocalInstruction( VariableOperator.get, varIndex2, localVariables, javaCodePos, lineNumber ) );
+        instructions.add( new WasmLocalInstruction( VariableOperator.get, varIndex1, localVariables, javaCodePos, lineNumber ) );
+    }
+
     /**
      * Add a global instruction
      * 
diff --git a/test/de/inetsoftware/jwebassembly/runtime/StructsGC.java b/test/de/inetsoftware/jwebassembly/runtime/StructsGC.java
index 1d44f7b..e85d766 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/StructsGC.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/StructsGC.java
@@ -132,9 +132,8 @@ public class StructsGC extends AbstractBaseTest {
         static int multipleAssign() {
             Abc2 val = new Abc2();
             for( int i = 0; i < 1_000; i++ ) {
-                val.a = 42;
-                // TODO
-                //val = val.abc = new Abc2();
+                val = val.abc = new Abc2();
+                val.a = i;
             }
             return val.a;
         }
diff --git a/test/de/inetsoftware/jwebassembly/runtime/StructsNonGC.java b/test/de/inetsoftware/jwebassembly/runtime/StructsNonGC.java
index 79804f0..3ed718d 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/StructsNonGC.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/StructsNonGC.java
@@ -26,6 +26,7 @@ import org.junit.runners.Parameterized.Parameters;
 import de.inetsoftware.jwebassembly.ScriptEngine;
 import de.inetsoftware.jwebassembly.WasmRule;
 import de.inetsoftware.jwebassembly.api.annotation.Export;
+import de.inetsoftware.jwebassembly.runtime.StructsGC.Abc2;
 import de.inetsoftware.jwebassembly.web.JSObject;
 
 public class StructsNonGC extends AbstractBaseTest {
@@ -140,9 +141,8 @@ public class StructsNonGC extends AbstractBaseTest {
         static int multipleAssign() {
             Abc2 val = new Abc2();
             for( int i = 0; i < 1_000; i++ ) {
-                val.a = 42;
-                // TODO
-                //val = val.abc = new Abc2();
+                val = val.abc = new Abc2();
+                val.a = i;
             }
             return val.a;
         }