simp_cmp_bijective_op improvement

Input expr such as "(ESP_init + 0xFFFFFFA8) == (ESP_init + @32[ESP_init + 0xFFFFFECC] * 0x2 + 0xFFFFFFA8)" resulted in empty args_a which caused "sanitycheck: ExprOp args must have same size!" in "arg_a = ExprOp(op, *args_a)".

1 files changed, 7 insertions, 0 deletions

diff --git a/miasm/expression/simplifications_common.py b/miasm/expression/simplifications_common.py
index f12ccfcf..f68b8ed5 100644
--- a/miasm/expression/simplifications_common.py
+++ b/miasm/expression/simplifications_common.py
@@ -1081,6 +1081,13 @@ def simp_cmp_bijective_op(expr_simp, expr):
             args_a.remove(value)
             args_b.remove(value)
 
+    # a + b == a + b + c
+    if not args_a:
+        return ExprOp(TOK_EQUAL, ExprOp(op, *args_b), ExprInt(0, args_b[0].size))
+    # a + b + c == a + b
+    if not args_b:
+        return ExprOp(TOK_EQUAL, ExprOp(op, *args_a), ExprInt(0, args_a[0].size))
+    
     arg_a = ExprOp(op, *args_a)
     arg_b = ExprOp(op, *args_b)
     return ExprOp(TOK_EQUAL, arg_a, arg_b)