From 47c28f7d4695833e7e568b8357aab591dcb4a042 Mon Sep 17 00:00:00 2001
From: Volker Berlin <volker.berlin@googlemail.com>
Date: Sun, 19 Jun 2022 14:09:49 +0200
Subject: [PATCH] use for IF conditions also a block with input parameter to
 prevent problems with not splitable instruction like DUP (Java) or TEE (Wasm)
 #43

---
 .../jwebassembly/module/BranchManager.java    | 14 +++-----
 .../jwebassembly/module/WasmCodeBuilder.java  | 36 +------------------
 2 files changed, 6 insertions(+), 44 deletions(-)

diff --git a/src/de/inetsoftware/jwebassembly/module/BranchManager.java b/src/de/inetsoftware/jwebassembly/module/BranchManager.java
index f4371de..dd2cb29 100644
--- a/src/de/inetsoftware/jwebassembly/module/BranchManager.java
+++ b/src/de/inetsoftware/jwebassembly/module/BranchManager.java
@@ -531,39 +531,35 @@ class BranchManager {
     private void calculateIf( BranchNode parent, IfParsedBlock startBlock, List<ParsedBlock> parsedOperations ) {
         IfPositions positions = searchElsePosition( startBlock, parsedOperations );
 
+        BlockType conditionType = getConditionType();
         BranchNode branch;
         int endPos = positions.elsePos;
+        int startPos = startBlock.nextPosition - 1;
         boolean createThenBlock = endPos <= parent.endPos;
         if( createThenBlock ) {
             // normal IF block
-            int startPos = startBlock.nextPosition;
 
             if( startPos > endPos ) {
                 // the condition in a do while(condition) loop
                 int breakDeep = calculateContinueDeep( parent, endPos );
-                instructions.add( findIdxOfCodePos( startPos ), new WasmBlockInstruction( WasmBlockOperator.BR_IF, breakDeep, startPos - 1, startBlock.lineNumber ) );
+                instructions.add( findIdxOfCodePos( startPos + 1 ), new WasmBlockInstruction( WasmBlockOperator.BR_IF, breakDeep, startPos, startBlock.lineNumber ) );
                 return;
             }
 
-            // find the code position where the condition values are push on the stack
-            List<WasmInstruction> instructions = this.instructions;
-            int idx = instructions.indexOf( startBlock.instr );
-            startPos = WasmCodeBuilder.findBlockStart( 1, instructions, idx + 1 );
             if( parent.overlapped( startPos ) ) {
                 branch = addMiddleNode( parent, parent.startPos, endPos );
             } else {
-                branch = new BranchNode( startPos, endPos, WasmBlockOperator.BLOCK, WasmBlockOperator.END );
+                branch = new BranchNode( startPos, endPos, WasmBlockOperator.BLOCK, WasmBlockOperator.END, conditionType );
                 parent.add( branch );
             }
         } else {
             branch = parent;
             // a jump outside of the parent, we will create the block later
         }
-        breakOperations.add( new BreakBlock( WasmBlockOperator.BR_IF, branch, startBlock.nextPosition - 1, startBlock.endPosition ) );
+        breakOperations.add( new BreakBlock( WasmBlockOperator.BR_IF, branch, startPos, startBlock.endPosition ) );
 
         for( int i = 0; i < positions.ifCount; i++ ) {
             IfParsedBlock parsedBlock = (IfParsedBlock)parsedOperations.remove( 0 );
-            //instructions.remove( parsedBlock.jump );
             breakOperations.add( new BreakBlock( WasmBlockOperator.BR_IF, branch, parsedBlock.nextPosition - 1, parsedBlock.endPosition ) );
         }
 
diff --git a/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java b/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
index 888c87e..995cb4e 100644
--- a/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
+++ b/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
@@ -15,7 +15,6 @@
  */
 package de.inetsoftware.jwebassembly.module;
 
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
@@ -156,39 +155,6 @@ public abstract class WasmCodeBuilder {
         return false;
     }
 
-    /**
-     * We need a value (or several) from the stack inside a block. We need to find the WasmInstruction where the block
-     * can can begin. If it is a function call or a numeric expression, it can be complicated to find the right point.
-     * 
-     * @param count
-     *            the count of values on the stack back. 1 means the last value. 2 means the penultimate value.
-     * @param instructions
-     *            the instruction list for searching
-     * @param idx
-     *            the start index for the search. Between 0 and instructions.size().
-     * @return the code position that push the last instruction
-     */
-    static int findBlockStart( int count, List<WasmInstruction> instructions, int idx ) {
-        int valueCount = 0;
-        for( int i = idx - 1; i >= 0; i-- ) {
-            WasmInstruction instr = instructions.get( i );
-            AnyType valueType = instr.getPushValueType();
-            if( valueType != null ) {
-                valueCount++;
-            }
-            int popCount = instr.getPopCount();
-            valueCount -= popCount;
-            if( valueCount == count && popCount == 0 ) {
-                int codePos = instr.getCodePosition();
-                if( i == 0 || instructions.get( i - 1 ).getCodePosition() < codePos ) {
-                    // if the same codePos is used from multiple instructions then it is not an atomic operation in Java
-                    return codePos;
-                }
-            }
-        }
-        throw new WasmException( "Block start position not found", -1 ); // should never occur
-    }
-
     /**
      * We need the value type from the stack.
      * 
@@ -210,7 +176,7 @@ public abstract class WasmCodeBuilder {
      *            the count of values on the stack back. 1 means the last value. 2 means the penultimate value.
      * @param javaCodePos
      *            current code position for which the stack is inspected
-     * @return
+     * @return the type
      */
     @Nonnull
     AnyType findArrayTypeFromStack( int count, int javaCodePos ) {