Symbexec: add apply_expr, taking in account side effects

2 files changed, 18 insertions, 2 deletions

diff --git a/miasm2/ir/symbexec.py b/miasm2/ir/symbexec.py
index 9ac79b1f..ba19ccf7 100644
--- a/miasm2/ir/symbexec.py
+++ b/miasm2/ir/symbexec.py
@@ -336,7 +336,6 @@ class symbexec(object):
                 val = self.symbols[a][ptr_diff * 8 + b.size:a.size]
                 out.append((m2_expr.ExprMem(ex, val.size), val))
         return out
-
     # give mem stored overlapping requested mem ptr
     def get_mem_overlapping(self, e, eval_cache=None):
         if eval_cache is None:
@@ -452,3 +451,16 @@ class symbexec(object):
             if m.arg == 1:
                 del self.symbols[mem]
 
+    def apply_expr(self, expr):
+        """Evaluate @expr and apply side effect if needed (ie. if expr is an
+        assignment). Return the evaluated value"""
+
+        # Eval expression
+        to_eval = expr.src if isinstance(expr, m2_expr.ExprAff) else expr
+        ret = self.expr_simp(self.eval_expr(to_eval))
+
+        # Update value if needed
+        if isinstance(expr, m2_expr.ExprAff):
+            self.eval_ir([m2_expr.ExprAff(expr.dst, ret)])
+
+        return ret
diff --git a/test/ir/symbexec.py b/test/ir/symbexec.py
index 1d87b470..9165fccb 100644
--- a/test/ir/symbexec.py
+++ b/test/ir/symbexec.py
@@ -7,7 +7,8 @@ import unittest
 class TestSymbExec(unittest.TestCase):
 
     def test_ClassDef(self):
-        from miasm2.expression.expression import ExprInt32, ExprId, ExprMem, ExprCompose
+        from miasm2.expression.expression import ExprInt32, ExprId, ExprMem, \
+            ExprCompose, ExprAff
         from miasm2.arch.x86.sem import ir_x86_32
         from miasm2.ir.symbexec import symbexec
 
@@ -52,6 +53,9 @@ class TestSymbExec(unittest.TestCase):
         self.assertEqual(set(e.modified()), set(e.symbols))
         self.assertRaises(
             KeyError, e.symbols.__getitem__, ExprMem(ExprInt32(100)))
+        self.assertEqual(e.apply_expr(id_eax), addr0)
+        self.assertEqual(e.apply_expr(ExprAff(id_eax, addr9)), addr9)
+        self.assertEqual(e.apply_expr(id_eax), addr9)
 
 if __name__ == '__main__':
     testsuite = unittest.TestLoader().loadTestsFromTestCase(TestSymbExec)