Simplifications: add high level to low level reduction

1 files changed, 155 insertions, 0 deletions

diff --git a/miasm2/expression/simplifications_explicit.py b/miasm2/expression/simplifications_explicit.py
new file mode 100644
index 00000000..78e056ec
--- /dev/null
+++ b/miasm2/expression/simplifications_explicit.py
@@ -0,0 +1,155 @@
+from miasm2.expression.modint import size2mask
+from miasm2.expression.expression import ExprInt, ExprCond, ExprOp, \
+    ExprCompose
+
+
+def simp_ext(_, expr):
+    if expr.op.startswith('zeroExt_'):
+        arg = expr.args[0]
+        if expr.size == arg.size:
+            return arg
+        return ExprCompose(arg, ExprInt(0, expr.size - arg.size))
+
+    if expr.op.startswith("signExt_"):
+        arg = expr.args[0]
+        add_size = expr.size - arg.size
+        new_expr = ExprCompose(
+            arg,
+            ExprCond(
+                arg.msb(),
+                ExprInt(size2mask(add_size), add_size),
+                ExprInt(0, add_size)
+            )
+        )
+        return new_expr
+    return expr
+
+
+def simp_flags(_, expr):
+    args = expr.args
+
+    if expr.is_op("FLAG_EQ"):
+        return ExprCond(args[0], ExprInt(0, 1), ExprInt(1, 1))
+
+    elif expr.is_op("FLAG_EQ_AND"):
+        op1, op2 = args
+        return ExprCond(op1 & op2, ExprInt(0, 1), ExprInt(1, 1))
+
+    elif expr.is_op("FLAG_SIGN_SUB"):
+        return (args[0] - args[1]).msb()
+
+    elif expr.is_op("FLAG_EQ_CMP"):
+        return ExprCond(
+            args[0] - args[1],
+            ExprInt(0, 1),
+            ExprInt(1, 1),
+        )
+
+    elif expr.is_op("FLAG_ADD_CF"):
+        op1, op2 = args
+        res = op1 + op2
+        return (((op1 ^ op2) ^ res) ^ ((op1 ^ res) & (~(op1 ^ op2)))).msb()
+
+    elif expr.is_op("FLAG_SUB_CF"):
+        op1, op2 = args
+        res = op1 - op2
+        return (((op1 ^ op2) ^ res) ^ ((op1 ^ res) & (op1 ^ op2))).msb()
+
+    elif expr.is_op("FLAG_ADD_OF"):
+        op1, op2 = args
+        res = op1 + op2
+        return (((op1 ^ res) & (~(op1 ^ op2)))).msb()
+
+    elif expr.is_op("FLAG_SUB_OF"):
+        op1, op2 = args
+        res = op1 - op2
+        return (((op1 ^ res) & (op1 ^ op2))).msb()
+
+    elif expr.is_op("FLAG_EQ_ADDWC"):
+        op1, op2, op3 = args
+        return ExprCond(
+            op1 + op2 + op3.zeroExtend(op1.size),
+            ExprInt(0, 1),
+            ExprInt(1, 1),
+        )
+
+    elif expr.is_op("FLAG_ADDWC_OF"):
+        op1, op2, op3 = args
+        res = op1 + op2 + op3.zeroExtend(op1.size)
+        return (((op1 ^ res) & (~(op1 ^ op2)))).msb()
+
+    elif expr.is_op("FLAG_SUBWC_OF"):
+        op1, op2, op3 = args
+        res = op1 - (op2 + op3.zeroExtend(op1.size))
+        return (((op1 ^ res) & (op1 ^ op2))).msb()
+
+    elif expr.is_op("FLAG_ADDWC_CF"):
+        op1, op2, op3 = args
+        res = op1 + op2 + op3.zeroExtend(op1.size)
+        return (((op1 ^ op2) ^ res) ^ ((op1 ^ res) & (~(op1 ^ op2)))).msb()
+
+    elif expr.is_op("FLAG_SUBWC_CF"):
+        op1, op2, op3 = args
+        res = op1 - (op2 + op3.zeroExtend(op1.size))
+        return (((op1 ^ op2) ^ res) ^ ((op1 ^ res) & (op1 ^ op2))).msb()
+
+    elif expr.is_op("FLAG_SIGN_ADDWC"):
+        op1, op2, op3 = args
+        return (op1 + op2 + op3.zeroExtend(op1.size)).msb()
+
+    elif expr.is_op("FLAG_SIGN_SUBWC"):
+        op1, op2, op3 = args
+        return (op1 - (op2 + op3.zeroExtend(op1.size))).msb()
+
+
+    elif expr.is_op("FLAG_EQ_SUBWC"):
+        op1, op2, op3 = args
+        res = op1 - (op2 + op3.zeroExtend(op1.size))
+        return ExprCond(res, ExprInt(0, 1), ExprInt(1, 1))
+
+    elif expr.is_op("CC_U<="):
+        op_cf, op_zf = args
+        return op_cf | op_zf
+
+    elif expr.is_op("CC_U>="):
+        op_cf, = args
+        return ~op_cf
+
+    elif expr.is_op("CC_S<"):
+        op_nf, op_of = args
+        return op_nf ^ op_of
+
+    elif expr.is_op("CC_S>"):
+        op_nf, op_of, op_zf = args
+        return ~(op_zf | (op_nf ^ op_of))
+
+    elif expr.is_op("CC_S<="):
+        op_nf, op_of, op_zf = args
+        return op_zf | (op_nf ^ op_of)
+
+    elif expr.is_op("CC_S>="):
+        op_nf, op_of = args
+        return ~(op_nf ^ op_of)
+
+    elif expr.is_op("CC_U>"):
+        op_cf, op_zf = args
+        return ~(op_cf | op_zf)
+
+    elif expr.is_op("CC_U<"):
+        op_cf, = args
+        return op_cf
+
+    elif expr.is_op("CC_NEG"):
+        op_nf, = args
+        return op_nf
+
+    elif expr.is_op("CC_EQ"):
+        op_zf, = args
+        return op_zf
+
+    elif expr.is_op("CC_NE"):
+        op_zf, = args
+        return ~op_zf
+
+    return expr
+