Fixed: AS decompilation - §§push before loop

CHANGELOG.md

@@ -30,6 +30,7 @@ All notable changes to this project will be documented in this file.
 - Rename invalid identifiers renames identifiers with a dollar sign
 - [#1676] Messages on movie tags when Flash Player ActiveX not available
 - [#1677] DefineFont2/3 - missing codeTableOffset if numGlyphs is zero and font has layout
+- AS decompilation - §§push before loop
 
 ## [14.3.1] - 2021-03-25
 ### Fixed

libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/graph/AVM2Graph.java

@@ -1611,7 +1611,7 @@ public class AVM2Graph extends Graph {
     }
 
     @Override
-    protected GraphTargetItem checkLoop(List<GraphTargetItem> output, LoopItem loopItem, BaseLocalData localData, List<Loop> loops, List<ThrowState> throwStates) {
+    protected GraphTargetItem checkLoop(List<GraphTargetItem> output, LoopItem loopItem, BaseLocalData localData, List<Loop> loops, List<ThrowState> throwStates, TranslateStack stack) {
         AVM2LocalData aLocalData = (AVM2LocalData) localData;
         if (loopItem instanceof WhileItem) {
             WhileItem w = (WhileItem) loopItem;
@@ -1620,6 +1620,22 @@ public class AVM2Graph extends Graph {
                 HasNextAVM2Item hn = (HasNextAVM2Item) w.expression.get(w.expression.size() - 1);
                 if (hn.obj != null) {
                     if (hn.obj.getNotCoerced().getThroughRegister().getNotCoerced() instanceof FilteredCheckAVM2Item) {
+
+                        //All items are moved from stack to output before entering while,
+                        // this code block moves them back to stack
+                        int pushnum = 0;
+                        for (int i = output.size() - 2 /*last is loop*/; i >= 0; i--) {
+                            if (output.get(i) instanceof PushItem) {
+                                pushnum++;
+                            } else {
+                                break;
+                            }
+                        }
+                        int rem = output.size() - 1 - pushnum;
+                        for (int i = output.size() - 1 - pushnum; i <= output.size() - 2; i++) {
+                            stack.push(((PushItem) output.remove(rem)).value);
+                        }
+                        //---------- end moving back to stack
                         if (w.commands.size() >= 3) {
                             int pos = 0;
                             Set<Integer> localRegsToKill = new HashSet<>();

libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/action/model/FunctionActionItem.java

@@ -35,6 +35,7 @@ import com.jpexs.decompiler.graph.GraphSourceItemPos;
 import com.jpexs.decompiler.graph.GraphTargetItem;
 import com.jpexs.decompiler.graph.GraphTargetVisitorInterface;
 import com.jpexs.decompiler.graph.SourceGenerator;
+import com.jpexs.decompiler.graph.model.BranchStackResistant;
 import com.jpexs.decompiler.graph.model.LocalData;
 import com.jpexs.helpers.Helper;
 import java.util.ArrayList;
@@ -48,7 +49,7 @@ import java.util.Set;
  *
  * @author JPEXS
  */
-public class FunctionActionItem extends ActionItem {
+public class FunctionActionItem extends ActionItem implements BranchStackResistant {
 
     public List<GraphTargetItem> actions;
 

libsrc/ffdec_lib/src/com/jpexs/decompiler/graph/Graph.java

@@ -1350,7 +1350,7 @@ public class Graph {
         return printGraph(foundGotos, partCodes, partCodePos, visited, localData, stack, allParts, parent, part, stopPart, stopPartKind, loops, throwStates, null, staticOperation, path, 0);
     }
 
-    protected GraphTargetItem checkLoop(List<GraphTargetItem> output, LoopItem loopItem, BaseLocalData localData, List<Loop> loops, List<ThrowState> throwStates) {
+    protected GraphTargetItem checkLoop(List<GraphTargetItem> output, LoopItem loopItem, BaseLocalData localData, List<Loop> loops, List<ThrowState> throwStates, TranslateStack stack) {
         return loopItem;
     }
 
@@ -1901,6 +1901,9 @@ public class Graph {
             }
         }
 
+        if (isLoop) {
+            makeAllCommands(ret, stack);
+        }
         if (debugPrintGraph) {
             System.err.println("loopsize:" + loops.size());
         }
@@ -2675,7 +2678,7 @@ public class Graph {
             }
             currentLoop.phase = 2;
 
-            GraphTargetItem replaced = checkLoop(ret, li, localData, loops, throwStates);
+            GraphTargetItem replaced = checkLoop(ret, li, localData, loops, throwStates, sPreLoop);
             if (replaced != li) {
                 int index = ret.indexOf(li);
                 ret.remove(index);
@@ -2951,21 +2954,18 @@ public class Graph {
                 clen--;
             }
         }
-        while (stack.size() > 0) {
-            GraphTargetItem p = stack.pop();
+        for (int i = stack.size() - 1; i >= 0; i--) {
+            GraphTargetItem p = stack.get(i);
             if (p instanceof BranchStackResistant) {
                 continue;
             }
+            stack.remove(i);
             if (!(p instanceof PopItem)) {
-                if (p instanceof FunctionActionItem) {
+                if (isExit) {
+                    //ASC2 leaves some function calls unpopped on stack before returning from a method
                     commands.add(clen, p);
                 } else {
-                    if (isExit) {
-                        //ASC2 leaves some function calls unpopped on stack before returning from a method
-                        commands.add(clen, p);
-                    } else {
-                        commands.add(clen, new PushItem(p));
-                    }
+                    commands.add(clen, new PushItem(p));
                 }
             }
         }

libsrc/ffdec_lib/test/com/jpexs/decompiler/flash/as3decompile/ActionScript3AssembledDecompileTest.java

@@ -131,6 +131,22 @@ public class ActionScript3AssembledDecompileTest extends ActionScript3DecompileT
                 false);
     }
 
+    @Test
+    public void testPushWhile() {
+        decompileMethod("assembled", "testPushWhile", "var _loc3_:int = 5;\r\n"
+                + "§§push(obfuscated[\"xxx\"] = new [\"ByteArray\"]());\r\n"
+                + "§§push(50);\r\n"
+                + "while(§§dup(§§pop()))\r\n"
+                + "{\r\n"
+                + "§§dup(§§pop())[§§dup(§§dup(§§pop())).length] = 41 ^ 111;\r\n"
+                + "§§dup(§§pop())[§§dup(§§dup(§§pop())).length] = 9 ^ 84;\r\n"
+                + "§§push(§§pop() - 1);\r\n"
+                + "}\r\n"
+                + "§§pop();\r\n"
+                + "§§pop();\r\n",
+                false);
+    }
+
     @Test
     public void testSetSlotDup() {
         decompileMethod("assembled", "testSetSlotDup", "var _loc5_:int = 5;\r\n"

libsrc/ffdec_lib/testdata/as3_assembled/abc/as3_assembled-0/as3_assembled-0.main.asasm

@@ -28,5 +28,6 @@ program
  #include "tests/TestDecrementPrecedence.script.asasm"
  #include "tests/TestSwitchGoto.script.asasm"
  #include "tests/TestTryWhile.script.asasm"
+ #include "tests/TestPushWhile.script.asasm"
  ; place to add next
 end ; program

libsrc/ffdec_lib/testdata/as3_assembled/abc/as3_assembled-0/tests/TestPushWhile.class.asasm

@@ -0,0 +1,99 @@
+class
+ refid "tests:TestPushWhile"
+ instance QName(PackageNamespace("tests"), "TestPushWhile")
+  extends QName(PackageNamespace(""), "Object")
+  flag SEALED
+  flag PROTECTEDNS
+  protectedns ProtectedNamespace("tests:TestPushWhile")
+  iinit
+   refid "tests:TestPushWhile/instance/init"
+   body
+    maxstack 1
+    localcount 1
+    initscopedepth 4
+    maxscopedepth 5
+    code
+     getlocal0
+     pushscope
+
+     getlocal0
+     constructsuper      0
+
+     returnvoid
+    end ; code
+   end ; body
+  end ; method
+  trait method QName(PackageNamespace(""), "run")
+   method
+    refid "tests:TestPushWhile/instance/run"
+    returns QName(PackageNamespace(""), "void")
+    body
+     maxstack 2
+     localcount 4
+     initscopedepth 4
+     maxscopedepth 5
+     code
+            getlocal0
+            pushscope
+            pushbyte 5
+            setlocal 3
+            
+            pushstring "ByteArray"
+            dup
+            findpropstrict MultinameL([PackageNamespace("flash.utils","1")])
+            swap
+            constructprop MultinameL([PackageNamespace("flash.utils","1")]), 0
+            dup
+            getlex QName(PackageNamespace("","2"),"obfuscated")
+            swap
+            pushstring "xxx"
+            swap
+            setproperty MultinameL([PackageNamespace("","2")])
+            pushint 50
+   ofs0016:
+            label
+            dup
+            iffalse ofs0039
+            decrement_i
+            swap
+            dup
+            dup
+            getproperty QName(PackageNamespace("","2"),"length")
+            pushbyte 41
+            pushbyte 111
+            bitxor
+            setproperty MultinameL([PackageNamespace("","2")])
+            dup
+            dup
+            getproperty QName(PackageNamespace("","2"),"length")
+            pushbyte 9
+            pushbyte 84
+            bitxor
+            setproperty MultinameL([PackageNamespace("","2")])
+            swap
+            jump ofs0016
+   ofs0039:
+            pop
+            pop
+            returnvoid
+     end ; code
+    end ; body
+   end ; method
+  end ; trait
+ end ; instance
+ cinit
+  refid "tests:TestPushWhile/class/init"
+  body
+   maxstack 1
+   localcount 1
+   initscopedepth 3
+   maxscopedepth 4
+   code
+    getlocal0
+    pushscope
+
+    returnvoid
+   end ; code
+  end ; body
+ end ; method
+end ; class

libsrc/ffdec_lib/testdata/as3_assembled/abc/as3_assembled-0/tests/TestPushWhile.script.asasm

@@ -0,0 +1,29 @@
+script
+ sinit
+  refid "tests:TestPushWhile/init"
+  body
+   maxstack 2
+   localcount 1
+   initscopedepth 1
+   maxscopedepth 3
+   code
+    getlocal0
+    pushscope
+
+    findpropstrict      Multiname("TestPushWhile", [PackageNamespace("tests")])
+    getlex              QName(PackageNamespace(""), "Object")
+    pushscope
+
+    getlex              Multiname("Object", [PrivateNamespace(null, "tests:TestPushWhile"), PackageNamespace(""), PackageNamespace("tests"), PackageInternalNs("tests"), Namespace("http://adobe.com/AS3/2006/builtin")])
+    newclass            "tests:TestPushWhile"
+    popscope
+    initproperty        QName(PackageNamespace("tests"), "TestPushWhile")
+
+    returnvoid
+   end ; code
+  end ; body
+ end ; method
+ trait class QName(PackageNamespace("tests"), "TestPushWhile")
+  #include "TestPushWhile.class.asasm"
+ end ; trait
+end ; script