3 files changed, 26 insertions, 6 deletions
diff --git a/miasm2/expression/expression.py b/miasm2/expression/expression.py
index 5ea596ae..b8266bf7 100644
--- a/miasm2/expression/expression.py
+++ b/miasm2/expression/expression.py
@@ -644,7 +644,7 @@ class ExprLoc(Expr):
         return Expr.get_object(cls, (loc_key, size))
 
     def __str__(self):
-        return "label_%d" % self._loc_key.key
+        return "loc_%d" % self._loc_key.key
 
     def get_r(self, mem_read=False, cst_read=False):
         return set()
diff --git a/miasm2/expression/expression_reduce.py b/miasm2/expression/expression_reduce.py
index 45386ca2..22ac8d8d 100644
--- a/miasm2/expression/expression_reduce.py
+++ b/miasm2/expression/expression_reduce.py
@@ -4,8 +4,8 @@ Apply reduction rules to an Expression ast
 """
 
 import logging
-from miasm2.expression.expression import ExprInt, ExprId, ExprOp, ExprSlice,\
-    ExprCompose, ExprMem, ExprCond
+from miasm2.expression.expression import ExprInt, ExprId, ExprLoc, ExprOp, \
+    ExprSlice, ExprCompose, ExprMem, ExprCond
 
 log_reduce = logging.getLogger("expr_reduce")
 console_handler = logging.StreamHandler()
@@ -29,7 +29,7 @@ class ExprNode(object):
         expr = self.expr
         if self.info is not None:
             out = repr(self.info)
-        elif expr.is_int() or expr.is_id():
+        elif expr.is_int() or expr.is_id() or expr.is_loc():
             out = str(expr)
         elif expr.is_mem():
             out = "@%d[%r]" % (self.expr.size, self.arg)
@@ -76,7 +76,7 @@ class ExprReducer(object):
         @expr: Expression to analyze
         """
 
-        if isinstance(expr, (ExprId, ExprInt)):
+        if isinstance(expr, (ExprId, ExprLoc, ExprInt)):
             node = ExprNode(expr)
         elif isinstance(expr, (ExprMem, ExprSlice)):
             son = self.expr2node(expr.arg)
@@ -118,7 +118,7 @@ class ExprReducer(object):
 
         expr = node.expr
         log_reduce.debug("\t" * lvl + "Reduce...: %s", node.expr)
-        if isinstance(expr, (ExprId, ExprInt)):
+        if isinstance(expr, (ExprId, ExprInt, ExprLoc)):
             pass
         elif isinstance(expr, ExprMem):
             arg = self.categorize(node.arg, lvl=lvl + 1, **kwargs)
diff --git a/miasm2/expression/simplifications_common.py b/miasm2/expression/simplifications_common.py
index 13b25ce2..149c5b8d 100644
--- a/miasm2/expression/simplifications_common.py
+++ b/miasm2/expression/simplifications_common.py
@@ -250,6 +250,26 @@ def simp_cst_propagation(e_s, expr):
             e_s(Y.msb()) == ExprInt(0, 1)):
             args = [args[0].args[0], X + Y]
 
+    # ((var >> int1) << int1) => var & mask
+    # ((var << int1) >> int1) => var & mask
+    if (op_name in ['<<', '>>'] and
+        args[0].is_op() and
+        args[0].op in ['<<', '>>'] and
+        op_name != args[0]):
+        var = args[0].args[0]
+        int1 = args[0].args[1]
+        int2 = args[1]
+        if int1 == int2 and int1.is_int() and int(int1) < expr.size:
+            if op_name == '>>':
+                mask = ExprInt((1 << (expr.size - int(int1))) - 1, expr.size)
+            else:
+                mask = ExprInt(
+                    ((1 << int(int1)) - 1) ^ ((1 << expr.size) - 1),
+                    expr.size
+                )
+            ret = var & mask
+            return ret
+
     # ((A & A.mask)
     if op_name == "&" and args[-1] == expr.mask:
         return ExprOp('&', *args[:-1])