From 442e0c896c6a48c1f0e8f832546640b314ca5274 Mon Sep 17 00:00:00 2001
From: Volker Berlin <volker.berlin@googlemail.com>
Date: Mon, 6 Jun 2022 15:21:14 +0200
Subject: [PATCH] Use the normal break handling for the GOTO in the CASEs of an
 SWITCH. This eliminates the need to calculate the end of the SWITCH
 structure. #43

---
 .../jwebassembly/module/BranchManager.java    | 75 +++++--------------
 .../runtime/ControlFlowOperators.java         | 37 +++++++++
 2 files changed, 55 insertions(+), 57 deletions(-)

diff --git a/src/de/inetsoftware/jwebassembly/module/BranchManager.java b/src/de/inetsoftware/jwebassembly/module/BranchManager.java
index 9ff111d..77f9dca 100644
--- a/src/de/inetsoftware/jwebassembly/module/BranchManager.java
+++ b/src/de/inetsoftware/jwebassembly/module/BranchManager.java
@@ -940,55 +940,7 @@ class BranchManager {
             }
         }
 
-        // handle the GOTO (breaks) at the end of the CASE blocks.
-        int lastBlockPosition = lastPosition;
-        for( Iterator<ParsedBlock> it = parsedOperations.iterator(); it.hasNext(); ) {
-            ParsedBlock parsedBlock = it.next();
-            int start = parsedBlock.startPosition;
-            if( start >= lastBlockPosition ) {
-                break;
-            }
-            switch( parsedBlock.op ) {
-                case GOTO:
-                case IF:
-                    int end = parsedBlock.endPosition;
-                    if( start < end ) {
-                        BranchNode branch = blockNode;
-                        while( branch.size() > 0 ) {
-                            BranchNode node = branch.get( 0 );
-                            if( start > node.endPos ) {
-                                if( end >= branch.endPos ) {
-                                    blockCount = 0;
-                                    BranchNode parentNode = branch;
-                                    while( parentNode != null && end > parentNode.endPos ) {
-                                        parentNode = parentNode.parent;
-                                        blockCount++;
-                                    }
-                                    WasmBlockOperator startOp;
-                                    if( parsedBlock.op == JavaBlockOperator.GOTO ) {
-                                        startOp = WasmBlockOperator.BR;
-                                        lastPosition = Math.max( lastPosition, end );
-                                    } else {
-                                        startOp = WasmBlockOperator.BR_IF;
-                                        instructions.remove( ((IfParsedBlock)parsedBlock).jump );
-                                    }
-                                    start++;
-                                    branch.add( new BranchNode( start, start, startOp, null, blockCount ) );
-                                    it.remove();
-                                }
-                                break;
-                            }
-                            branch = node;
-                        }
-
-                    }
-            }
-        }
-
-        // Create the main block around the switch
-        BranchNode switchNode = new BranchNode( startPosition, lastPosition, WasmBlockOperator.BLOCK, WasmBlockOperator.END, switchType );
-        switchNode.add( blockNode );
-        parent.add( switchNode );
+        parent.add( blockNode );
 
         if( brTableNode != null ) {
             // sort back in the natural order and create a br_table 
@@ -1000,11 +952,11 @@ class BranchManager {
             brTableNode.data = data;
         }
 
-        for( int i = 0; i < cases.length; i++ ) {
-            switchCase = cases[i];
-            calculateSubOperations( switchCase.node, parsedOperations );
-        }
-        calculateSubOperations( switchNode, parsedOperations );
+        blockNode = cases[0].node;
+        do {
+            calculateSubOperations( blockNode, parsedOperations );
+            blockNode = blockNode.parent;
+        } while( blockNode != parent );
     }
 
     /**
@@ -1473,8 +1425,7 @@ class BranchManager {
      * @return the new node
      */
     private BranchNode addMiddleNode( BranchNode parent, int startPos, int endPos ) {
-        Object data = parent.data == switchType && parent.startPos == startPos ? switchType : null;
-        BranchNode middleNode = new BranchNode( startPos, endPos, WasmBlockOperator.BLOCK, WasmBlockOperator.END, data );
+        BranchNode middleNode = new BranchNode( startPos, endPos, WasmBlockOperator.BLOCK, WasmBlockOperator.END );
         int idx = 0;
         for( Iterator<BranchNode> it = parent.iterator(); it.hasNext(); ) {
             BranchNode child = it.next();
@@ -1488,8 +1439,18 @@ class BranchManager {
             middleNode.add( child );
             it.remove();
         }
+
+        // use same input parameter if parent or child start on same position
+        if( parent.startPos == startPos ) {
+            middleNode.data = parent.data;
+        } else if( middleNode.size() > 0 ) {
+            BranchNode child = middleNode.get( 0 );
+            if( child.startPos == startPos ) {
+                middleNode.data = child.data;
+            }
+        }
+
         parent.add( idx, middleNode );
-        parent = middleNode;
         patchBrDeep( middleNode );
         return middleNode;
     }
diff --git a/test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java b/test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java
index 566569e..b98f432 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/ControlFlowOperators.java
@@ -47,6 +47,7 @@ public class ControlFlowOperators extends AbstractBaseTest {
             addParam( list, script, "ifCompare" );
             addParam( list, script, "switchDirect" );
             addParam( list, script, "switchWithConditionMethodParams" );
+            addParam( list, script, "switchWithConditionSelect" );
             addParam( list, script, "endlessLoop" );
             addParam( list, script, "doWhileLoop" );
             addParam( list, script, "doWhileLoopTwoConditions" );
@@ -303,6 +304,42 @@ public class ControlFlowOperators extends AbstractBaseTest {
             return last;
         }
 
+        @Export
+        private static int switchWithConditionSelect() {
+            boolean cond = true;
+            int c1 = 1;
+            int c2 = 2;
+            int b;
+            switch( cond ? c1 : c2 ) {
+                case 1:
+                    b = 17;
+                    switch( cond ? c1 : c2 ) {
+                        case 1:
+                            b = 13;
+                            break;
+                        case 2:
+                            b = 14;
+                            break;
+                    }
+                    break;
+                case 2:
+                case 1001:
+                    if( c1 == 1000 ) {
+                        b = 1000;
+                        break;
+                    } else {
+                        b = 1001;
+                    }
+                    //$FALL-THROUGH$
+                case Integer.MAX_VALUE:
+                    b = 3;
+                    break;
+                default:
+                    b = 9;
+            }
+            return b;
+        }
+
         @Export
         static int endlessLoop() {
             int a = 0;