From 062e2aeb47cf7aa8c677415c6e12d9151dfa1ce1 Mon Sep 17 00:00:00 2001
From: Volker Berlin <volker.berlin@googlemail.com>
Date: Thu, 16 Jun 2022 22:47:22 +0200
Subject: [PATCH] fix while(true) inside a while(true) loop. #43

---
 .../jwebassembly/module/BranchManager.java    | 18 +++++++++++++---
 .../runtime/ControlFlowOperators.java         | 21 +++++++++++++++++++
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/src/de/inetsoftware/jwebassembly/module/BranchManager.java b/src/de/inetsoftware/jwebassembly/module/BranchManager.java
index f57c75be..f456c2e3 100644
--- a/src/de/inetsoftware/jwebassembly/module/BranchManager.java
+++ b/src/de/inetsoftware/jwebassembly/module/BranchManager.java
@@ -202,7 +202,7 @@ private void addLoops( List<ParsedBlock> parsedOperations ) {
                         if( loop == null ) {
                             loop = new ParsedBlock( JavaBlockOperator.LOOP, start, 0, start, parsedBlock.lineNumber );
                             loops.put( start, loop );
-                            // if a condition form outside of the loop point inside the loop then it must be conditional return and a jump to the loop condition.
+                            // if a condition before the loop points to a position within the loop, then it must be a conditional return and a jump to the loop condition.
                             for( int n = b - 1; n >= 0; n-- ) {
                                 ParsedBlock prevBlock = parsedOperations.get( n );
                                 switch( prevBlock.op ) {
@@ -221,8 +221,20 @@ private void addLoops( List<ParsedBlock> parsedOperations ) {
                                 }
                             }
                         }
-                        loop.nextPosition = parsedBlock.startPosition; // Jump position for Continue
-                        loop.endPosition = parsedBlock.nextPosition;
+                        if( loop.endPosition < parsedBlock.nextPosition ) {
+                            int nextPosition = parsedBlock.startPosition; // Jump position for Continue
+                            int endPosition = parsedBlock.nextPosition;
+                            // if a condition behind the loop points to a position inside the loop, the loop must be extended to avoid overlapping blocks.
+                            for( int n = b + 1; n < parsedOperations.size(); n++ ) {
+                                ParsedBlock block = parsedOperations.get( n );
+                                if( block.startPosition > endPosition && endPosition > block.endPosition && block.endPosition > start ) {
+                                    nextPosition = block.startPosition;
+                                    endPosition = block.nextPosition;
+                                }
+                            }
+                            loop.nextPosition = nextPosition; // Jump position for Continue
+                            loop.endPosition = endPosition;
+                        }
                         break;
                     default:
                         throw new WasmException( "Unimplemented loop code operation: " + parsedBlock.op, parsedBlock.lineNumber );
diff --git a/test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java b/test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java
index b98f4321..a6f25119 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java
@@ -59,6 +59,7 @@ public static Collection<Object[]> data() {
             addParam( list, script, "whileLoopInElseAfterReturn" );
             addParam( list, script, "whileLoopAfterIfWithReturn" );
             addParam( list, script, "whileLoopInsideLoop" );
+            addParam( list, script, "whileTrueInsideWhileTrue" );
             addParam( list, script, "forLoop" );
             addParam( list, script, "conditionalOperator" );
             addParam( list, script, "conditionalOperator2" );
@@ -489,6 +490,26 @@ public static int whileLoopInsideLoop() {
             }
         }
 
+        @Export
+        static int whileTrueInsideWhileTrue() {
+            int sw = 1;
+            while( true ) {
+                if( sw != 1 ) {
+                    sw++;
+                    break;
+                }
+                sub: while( true ) {
+                    if( sw == 1 ) {
+                        sw = 2;
+                        break;
+                    } else {
+                        sw = 17;
+                    }
+                }
+            }
+            return sw;
+        }
+
         @Export
         static int forLoop() {
             int a = 0;