diff options
| -rw-r--r-- | miasm/expression/simplifications.py | 1 | ||||
| -rw-r--r-- | miasm/expression/simplifications_common.py | 70 | ||||
| -rw-r--r-- | test/expression/simplifications.py | 32 |
3 files changed, 103 insertions, 0 deletions
diff --git a/miasm/expression/simplifications.py b/miasm/expression/simplifications.py index 1d64456f..d8a11382 100644 --- a/miasm/expression/simplifications.py +++ b/miasm/expression/simplifications.py @@ -51,6 +51,7 @@ class ExpressionSimplifier(object): simplifications_common.simp_ext_eq_ext, simplifications_common.simp_cmp_int, + simplifications_common.simp_cmp_bijective_op, simplifications_common.simp_sign_inf_zeroext, simplifications_common.simp_cmp_int_int, simplifications_common.simp_ext_cst, diff --git a/miasm/expression/simplifications_common.py b/miasm/expression/simplifications_common.py index 69d56997..9db766d8 100644 --- a/miasm/expression/simplifications_common.py +++ b/miasm/expression/simplifications_common.py @@ -1004,6 +1004,76 @@ def simp_cmp_int_arg(_, expr): return ExprCond(ExprOp(op, arg1, arg2), src1, src2) + +def simp_cmp_bijective_op(expr_simp, expr): + """ + A + B == A => A == 0 + + X + A == X + B => A == B + X ^ A == X ^ B => A == B + + TODO: + 3 * A + B == A + C => 2 * A + B == C + """ + + if not expr.is_op(TOK_EQUAL): + return expr + op_a = expr.args[0] + op_b = expr.args[1] + + # a == a + if op_a == op_b: + return ExprInt(1, 1) + + # Case: + # a + b + c == a + if op_a.is_op() and op_a.op in ["+", "^"]: + args = list(op_a.args) + if op_b in args: + args.remove(op_b) + if not args: + raise ValueError("Can be here") + elif len(args) == 1: + op_a = args[0] + else: + op_a = ExprOp(op_a.op, *args) + return ExprOp(TOK_EQUAL, op_a, ExprInt(0, args[0].size)) + # a == a + b + c + if op_b.is_op() and op_b.op in ["+", "^"]: + args = list(op_b.args) + if op_a in args: + args.remove(op_a) + if not args: + raise ValueError("Can be here") + elif len(args) == 1: + op_b = args[0] + else: + op_b = ExprOp(op_b.op, *args) + return ExprOp(TOK_EQUAL, op_b, ExprInt(0, args[0].size)) + + if not (op_a.is_op() and op_b.is_op()): + return expr + if op_a.op != op_b.op: + return expr + op = op_a.op + if op not in ["+", "^"]: + return expr + common = set(op_a.args).intersection(op_b.args) + if not common: + return expr + + args_a = list(op_a.args) + args_b = list(op_b.args) + for value in common: + while value in args_a and value in args_b: + args_a.remove(value) + args_b.remove(value) + + arg_a = ExprOp(op, *args_a) + arg_b = ExprOp(op, *args_b) + return ExprOp(TOK_EQUAL, arg_a, arg_b) + + def simp_subwc_cf(_, expr): """SUBWC_CF(A, B, SUB_CF(C, D)) => SUB_CF({A, C}, {B, D})""" if not expr.is_op('FLAG_SUBWC_CF'): diff --git a/test/expression/simplifications.py b/test/expression/simplifications.py index de059075..f36a7b4d 100644 --- a/test/expression/simplifications.py +++ b/test/expression/simplifications.py @@ -522,6 +522,38 @@ to_test = [ ), + ( + ExprOp(TOK_EQUAL, a ^ b, a ^ c), + ExprOp(TOK_EQUAL, b , c) + ), + + ( + ExprOp(TOK_EQUAL, a + b, a + c), + ExprOp(TOK_EQUAL, b , c) + ), + + ( + ExprOp(TOK_EQUAL, a + b, a), + ExprOp(TOK_EQUAL, b , i0) + ), + + ( + ExprOp(TOK_EQUAL, a, a + b), + ExprOp(TOK_EQUAL, b , i0) + ), + + + ( + ExprOp(TOK_EQUAL, ExprOp("+", a, b, c), a), + ExprOp(TOK_EQUAL, b+c , i0) + ), + + ( + ExprOp(TOK_EQUAL, a, ExprOp("+", a, b, c)), + ExprOp(TOK_EQUAL, b+c , i0) + ), + + (ExprOp(TOK_INF_SIGNED, i1, i2), ExprInt(1, 1)), (ExprOp(TOK_INF_UNSIGNED, i1, i2), ExprInt(1, 1)), (ExprOp(TOK_INF_EQUAL_SIGNED, i1, i2), ExprInt(1, 1)), |