diff options
| -rw-r--r-- | miasm2/expression/simplifications_common.py | 20 | ||||
| -rw-r--r-- | test/expression/simplifications.py | 4 |
2 files changed, 24 insertions, 0 deletions
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]) diff --git a/test/expression/simplifications.py b/test/expression/simplifications.py index a4e839cf..b2591a83 100644 --- a/test/expression/simplifications.py +++ b/test/expression/simplifications.py @@ -177,6 +177,10 @@ to_test = [(ExprInt(1, 32) - ExprInt(1, 32), ExprInt(0, 32)), (ExprInt(0x4142, 32)[:32], ExprInt(0x4142, 32)), (ExprInt(0x4142, 32)[:8], ExprInt(0x42, 8)), (ExprInt(0x4142, 32)[8:16], ExprInt(0x41, 8)), + (ExprOp('>>', ExprOp('<<', a, ExprInt(0x4, 32)), ExprInt(0x4, 32)), + ExprOp('&', a, ExprInt(0x0FFFFFFF, 32))), + (ExprOp('<<', ExprOp('>>', a, ExprInt(0x4, 32)), ExprInt(0x4, 32)), + ExprOp('&', a, ExprInt(0xFFFFFFF0, 32))), (a[:32], a), (a[:8][:8], a[:8]), (a[:16][:8], a[:8]), |