From 66945d2974cd37f3dc41a5df9a7547e18d18611a Mon Sep 17 00:00:00 2001
From: Volker Berlin <volker.berlin@googlemail.com>
Date: Thu, 21 Mar 2019 21:14:21 +0100
Subject: [PATCH] improve "goto_w" support

---
 .../jwebassembly/module/BranchManger.java     | 82 +++++++++++++------
 .../jwebassembly/runtime/Wide.java            | 25 ++++--
 2 files changed, 72 insertions(+), 35 deletions(-)

diff --git a/src/de/inetsoftware/jwebassembly/module/BranchManger.java b/src/de/inetsoftware/jwebassembly/module/BranchManger.java
index 3653edc..3ea1641 100644
--- a/src/de/inetsoftware/jwebassembly/module/BranchManger.java
+++ b/src/de/inetsoftware/jwebassembly/module/BranchManger.java
@@ -179,37 +179,26 @@ class BranchManger {
                         int nextPos = parsedBlock.nextPosition;
                         for( int n = b + 1; n < allParsedOperations.size(); n++ ) {
                             ParsedBlock nextBlock = allParsedOperations.get( n );
-                            if( nextBlock.op == JavaBlockOperator.IF && nextBlock.endPosition == nextPos ) {
-                                int conditionStart = parsedBlock.endPosition; // 15
-                                int conditionEnd = nextBlock.nextPosition; // 22
-                                int conditionNew = parsedBlock.startPosition; // 4
-                                int conditionIdx = -1;
-
-                                int i;
-                                for( i = 0; i < instructions.size(); i++ ) {
-                                    WasmInstruction instr = instructions.get( i );
-                                    int codePos = instr.getCodePosition();
-                                    if( codePos == nextPos ) {
-                                        conditionIdx = i;
-                                    }
-                                    if( codePos >= conditionEnd ) {
-                                        break;
-                                    }
-                                    if( codePos >= conditionStart ) {
-                                        instr.setCodePosition( conditionNew );
-                                        instructions.remove( i );
-                                        instructions.add( conditionIdx++, instr );
-                                    }
-                                }
-
-                                parsedBlock.op = JavaBlockOperator.LOOP;
-                                parsedBlock.endPosition = conditionEnd;
+                            if( nextBlock.op == JavaBlockOperator.IF && nextBlock.endPosition == nextPos ) { // Eclipse loop with normal goto
+                                int conditionStart = parsedBlock.endPosition;
+                                int conditionEnd = nextBlock.nextPosition;
+                                convertToLoop( parsedBlock, conditionStart, conditionEnd );
                                 allParsedOperations.remove( n );
-                                instructions.add( i, new WasmBlockInstruction( WasmBlockOperator.BR, 0, conditionNew ) );
-                                instructions.add( conditionIdx++, new WasmBlockInstruction( WasmBlockOperator.BR_IF, 1, conditionNew ) );
                                 ((IfParsedBlock)nextBlock).negateCompare();
                                 break;
                             }
+                            if( nextBlock.op == JavaBlockOperator.GOTO && nextBlock.endPosition == nextPos && n > 1 ) { // Eclipse loop with wide goto_w
+                                ParsedBlock prevBlock = allParsedOperations.get( n - 1 );
+                                if( prevBlock.op == JavaBlockOperator.IF && prevBlock.endPosition == nextBlock.nextPosition ) {
+                                    System.err.println( nextBlock );
+                                    int conditionStart = parsedBlock.endPosition;
+                                    int conditionEnd = prevBlock.nextPosition;
+                                    convertToLoop( parsedBlock, conditionStart, conditionEnd );
+                                    allParsedOperations.remove( n );
+                                    allParsedOperations.remove( n - 1 );
+                                    break;
+                                }
+                            }
                         }
                         break;
                     default:
@@ -220,6 +209,45 @@ class BranchManger {
         allParsedOperations.addAll( loops.values() );
     }
 
+    /**
+     * Convert the GOTO block with condition at the end into a loop block and move the condition from the end to the
+     * start like wasm it required.
+     * 
+     * @param gotoBlock
+     *            the goto block
+     * @param conditionStart
+     *            the code position where condition code start
+     * @param conditionEnd
+     *            the end position
+     */
+    private void convertToLoop( ParsedBlock gotoBlock, int conditionStart, int conditionEnd ) {
+        int conditionNew = gotoBlock.startPosition;
+        int nextPos = gotoBlock.nextPosition;
+        int conditionIdx = -1;
+
+        int i;
+        for( i = 0; i < instructions.size(); i++ ) {
+            WasmInstruction instr = instructions.get( i );
+            int codePos = instr.getCodePosition();
+            if( codePos == nextPos ) {
+                conditionIdx = i;
+            }
+            if( codePos >= conditionEnd ) {
+                break;
+            }
+            if( codePos >= conditionStart ) {
+                instr.setCodePosition( conditionNew );
+                instructions.remove( i );
+                instructions.add( conditionIdx++, instr );
+            }
+        }
+
+        gotoBlock.op = JavaBlockOperator.LOOP;
+        gotoBlock.endPosition = conditionEnd;
+        instructions.add( i, new WasmBlockInstruction( WasmBlockOperator.BR, 0, conditionNew ) );
+        instructions.add( conditionIdx++, new WasmBlockInstruction( WasmBlockOperator.BR_IF, 1, conditionNew ) );
+    }
+
     /**
      * Calculate the branch tree for the given branch and parsed sub operations.
      * 
diff --git a/test/de/inetsoftware/jwebassembly/runtime/Wide.java b/test/de/inetsoftware/jwebassembly/runtime/Wide.java
index 346f532..f0c9b9e 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/Wide.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/Wide.java
@@ -39,26 +39,35 @@ public class Wide extends AbstractBaseTest {
         ArrayList<Object[]> list = new ArrayList<>();
         for( ScriptEngine[] val : ScriptEngine.testParams() ) {
             ScriptEngine script = val[0];
-            addParam( list, script, "abc" );
+            addParam( list, script, "thenBranch" );
+            addParam( list, script, "elseBranch" );
         }
         return list;
     }
 
     static class TestClass {
 
+        @Export
+        static int thenBranch() {
+            return wide(true);
+        }
+
+        @Export
+        static int elseBranch() {
+            return wide(false);
+        }
+
         /**
          * more as 255 variable slots
          * @return
          */
         @Export
-        static int abc() {
+        static int wide( boolean then) {
             int i = 42;
-            if( 42 == i ) {
-// TODO
-//                for( int j = 0; j < 10; j++ ) {
-//                    i++;
-//                }
-                i++;
+            if( then ) {
+                for( int j = 0; j < 10; j++ ) {
+                    i++;
+                }
             } else {
                 int j = 0;
                 long a0 = 0;