From 52819fcce7af4dbc90de90aa774c193b60805757 Mon Sep 17 00:00:00 2001
From: Jennifer Taylor <dragonminded@dragonminded.com>
Date: Sat, 5 Aug 2023 19:15:37 +0000
Subject: [PATCH] Fix a small bug with decompiler optimizer passes preventing
 MGA matching SWF decompilation.

---
 bemani/format/afp/swf.py             |  4 ++-
 bemani/format/afp/types/statement.py | 40 +++++++++++++++++-----------
 2 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/bemani/format/afp/swf.py b/bemani/format/afp/swf.py
index f2fcaee..56bc4e9 100644
--- a/bemani/format/afp/swf.py
+++ b/bemani/format/afp/swf.py
@@ -2232,7 +2232,9 @@ class SWF(VerboseOutput, TrackedCoverage):
                 ap2data[dataoffset : (dataoffset + 12)],
             )
             self.add_coverage(dataoffset, 12)
-            if flags != 0:
+
+            # TODO: There are some flags bits here that I do not understand.
+            if flags not in {0x0, 0x4}:
                 raise Exception(f"Unexpected flags {hex(flags)} in AP2_DEFINE_TEXT!")
 
             extra_data = 12 + (20 * text_data_count) + (4 * sub_data_total_count)
diff --git a/bemani/format/afp/types/statement.py b/bemani/format/afp/types/statement.py
index 8b879e7..44e57ee 100644
--- a/bemani/format/afp/types/statement.py
+++ b/bemani/format/afp/types/statement.py
@@ -748,16 +748,20 @@ def _negative_absorb_and(left: IfExpr, right: IfExpr) -> Optional[IfExpr]:
 
     for val in right_ors:
         if neg_left == val:
-            return AndIf(
-                left,
-                _accum_or([o for o in right_ors if o is not val]),
-            ).simplify()
+            other_ors = [o for o in right_ors if o is not val]
+            if other_ors:
+                return AndIf(
+                    left,
+                    _accum_or(other_ors),
+                ).simplify()
     for val in left_ors:
         if neg_right == val:
-            return AndIf(
-                _accum_or([o for o in left_ors if o is not val]),
-                right,
-            ).simplify()
+            other_ors = [o for o in left_ors if o is not val]
+            if other_ors:
+                return AndIf(
+                    _accum_or(other_ors),
+                    right,
+                ).simplify()
 
     return None
 
@@ -811,16 +815,20 @@ def _negative_absorb_or(left: IfExpr, right: IfExpr) -> Optional[IfExpr]:
 
     for val in right_ands:
         if neg_left == val:
-            return OrIf(
-                left,
-                _accum_and([o for o in right_ands if o is not val]),
-            ).simplify()
+            other_ands = [o for o in right_ands if o is not val]
+            if other_ands:
+                return OrIf(
+                    left,
+                    _accum_and(other_ands),
+                ).simplify()
     for val in left_ands:
         if neg_right == val:
-            return OrIf(
-                _accum_and([o for o in left_ands if o is not val]),
-                right,
-            ).simplify()
+            other_ands = [o for o in left_ands if o is not val]
+            if other_ands:
+                return OrIf(
+                    _accum_and(other_ands),
+                    right,
+                ).simplify()
 
     return None