Fix ppmm bug

Author: Kroppeb

src/org/jetbrains/java/decompiler/modules/decompiler/SimplifyExprentsHelper.java

@@ -683,20 +683,30 @@ private static boolean inlinePPIAndMMI(Exprent expr, Exprent next) {
   // Try to find the first valid usage of a variable for PPMM inlining.
   // Returns Pair{parent exprent, variable exprent to replace}
   private static Pair<Exprent, VarExprent> findFirstValidUsage(VarExprent match, Exprent next) {
-    Deque<Exprent> stack = new LinkedList<>();
+    List<Exprent> stack = new ArrayList<>();
+    List<Exprent> parent = new ArrayList<>();
     stack.add(next);
+    parent.add(null);
 
     while (!stack.isEmpty()) {
-      Exprent expr = stack.removeLast();
+      Exprent expr = stack.remove(stack.size() - 1);
+      Exprent parentExpr = parent.remove(parent.size() - 1);
 
       List<Exprent> exprents = expr.getAllExprents();
 
+      if (parentExpr != null &&
+        expr instanceof VarExprent ve &&
+        ve.getIndex() == match.getIndex() &&
+        ve.getVersion() == match.getVersion()) {
+        return Pair.of(parentExpr, ve);
+      }
+
       if (expr instanceof FunctionExprent) {
         FunctionExprent func = (FunctionExprent) expr;
 
         // Don't inline ppmm into more ppmm
         if (isPPMM(func)) {
-          continue;
+          return null;
         }
 
         // Don't consider || or &&
@@ -718,30 +728,14 @@ private static Pair<Exprent, VarExprent> findFirstValidUsage(VarExprent match, E
       // Reverse iteration to ensure DFS
       for (int i = exprents.size() - 1; i >= 0; i--) {
         Exprent ex = exprents.get(i);
-        boolean add = true;
 
         // Skip LHS of assignment as it is invalid
-        if (expr instanceof AssignmentExprent) {
-          add = ex != ((AssignmentExprent) expr).getLeft();
-        }
-
-        // Check var if we find
-        if (add && ex instanceof VarExprent) {
-          VarExprent ve = (VarExprent) ex;
-
-          if (ve.getIndex() == match.getIndex() && ve.getVersion() == match.getVersion()) {
-            return Pair.of(expr, ve);
-          }
-        }
-
-        // Ignore ++/-- exprents as they aren't valid usages to replace
-        if (ex instanceof FunctionExprent) {
-          add = !isPPMM((FunctionExprent) ex);
+        if (expr instanceof AssignmentExprent asExpr && ex == asExpr.getLeft()) {
+          continue;
         }
 
-        if (add) {
-          stack.add(ex);
-        }
+        stack.add(ex);
+        parent.add(expr);
       }
     }
 

testData/results/pkg/TestPPMM.dec

@@ -67,13 +67,15 @@ public class TestPPMM {
 
    public void doubleppi() {
       int a = 0;// 80
-      t2(++a, ++a);// 81 82 83
+      a++;// 81
+      t2(++a, a);// 82 83
       t2(++a, ++a);// 84 85
-      t2(++a, ++a);// 86 87
+      a++;// 86
+      t2(++a, a);// 87
       t2(++a, ++a);// 88 89
       t2(++a, a++);// 90 91
-      t2(a, ++a);// 92 93
-      t2(a, ++a);// 94
+      t2(++a, a);// 92 93
+      t2(++a, a);// 94
       t2(a++, a);// 95
       t2(a++, a);// 96
       t2(a, a++);// 97
@@ -286,97 +288,99 @@ class 'pkg/TestPPMM' {
       2      69
       3      69
       4      69
-      5      69
-      6      69
-      7      69
-      a      69
-      b      69
-      c      69
-      d      70
-      e      70
-      f      70
-      11      70
-      12      70
-      13      70
-      15      70
-      16      70
-      17      70
-      18      71
-      19      71
-      1a      71
-      1b      71
-      1c      71
-      1d      71
-      20      71
-      21      71
-      22      71
-      23      72
-      24      72
-      25      72
-      27      72
-      28      72
-      29      72
-      2b      72
-      2c      72
-      2d      72
-      2e      73
-      2f      73
-      30      73
-      33      73
-      34      73
-      35      73
-      36      73
-      37      73
-      38      73
-      39      74
-      3a      74
-      3b      74
-      3c      74
-      3e      74
-      3f      74
-      40      74
-      41      75
-      42      75
-      43      75
-      44      75
-      46      75
-      47      75
-      48      75
-      4a      76
-      4b      76
-      4c      76
-      4d      76
-      4e      76
-      4f      76
-      50      76
-      52      77
-      53      77
-      54      77
-      55      77
-      56      77
-      57      77
-      58      77
-      59      78
-      5b      78
-      5c      78
-      5d      78
-      5e      78
-      5f      78
-      60      78
-      61      79
-      62      79
-      63      79
-      64      79
-      65      79
-      66      80
+      5      70
+      6      70
+      7      70
+      9      70
+      a      70
+      b      70
+      c      70
+      d      71
+      e      71
+      f      71
+      11      71
+      12      71
+      13      71
+      15      71
+      16      71
+      17      71
+      18      72
+      19      72
+      1a      72
+      1b      73
+      1c      73
+      1d      73
+      1f      73
+      20      73
+      21      73
+      22      73
+      23      74
+      24      74
+      25      74
+      27      74
+      28      74
+      29      74
+      2b      74
+      2c      74
+      2d      74
+      2e      75
+      2f      75
+      30      75
+      33      75
+      34      75
+      35      75
+      36      75
+      37      75
+      38      75
+      39      76
+      3a      76
+      3b      76
+      3d      76
+      3e      76
+      3f      76
+      40      76
+      41      77
+      42      77
+      43      77
+      45      77
+      46      77
+      47      77
+      48      77
+      4a      78
+      4b      78
+      4c      78
+      4d      78
+      4e      78
+      4f      78
+      50      78
+      52      79
+      53      79
+      54      79
+      55      79
+      56      79
+      57      79
+      58      79
+      59      80
+      5b      80
+      5c      80
+      5d      80
+      5e      80
+      5f      80
+      60      80
+      61      81
+      62      81
+      63      81
+      64      81
+      65      81
+      66      82
    }
 
    method 't (I)V' {
-      0      83
+      0      85
    }
 
    method 't2 (II)V' {
-      0      86
+      0      88
    }
 }
 
@@ -431,23 +435,23 @@ Lines mapping:
 78 <-> 66
 80 <-> 69
 81 <-> 70
-82 <-> 70
-83 <-> 70
-84 <-> 71
-85 <-> 71
-86 <-> 72
-87 <-> 72
-88 <-> 73
-89 <-> 73
-90 <-> 74
-91 <-> 74
-92 <-> 75
-93 <-> 75
-94 <-> 76
-95 <-> 77
-96 <-> 78
-97 <-> 79
-98 <-> 80
-99 <-> 81
-102 <-> 84
-106 <-> 87
+82 <-> 71
+83 <-> 71
+84 <-> 72
+85 <-> 72
+86 <-> 73
+87 <-> 74
+88 <-> 75
+89 <-> 75
+90 <-> 76
+91 <-> 76
+92 <-> 77
+93 <-> 77
+94 <-> 78
+95 <-> 79
+96 <-> 80
+97 <-> 81
+98 <-> 82
+99 <-> 83
+102 <-> 86
+106 <-> 89