Contents

• class xform_expr
  • xform_expr Members
  • xform_expr Details

class xform_expr

Specifies parts of a query expression for step_xform.query() or step_xform.query_bounds().

Represents an expression of the form (ax+b)/c, where x is an attribute attached to the memory location obtained by applying a specified access path to a specified base symbol .

May also represent a constant expression b/c.

xform_expr Members

Constructor	__init__()
Methods	__repr__(), __str__()

xform_expr Details

class cs.xform_expr

Specifies parts of a query expression for step_xform.query() or step_xform.query_bounds().

__init__(_b[, _c = 1])

Constructor for a constant-valued xform_expr object with value b/c.

Parameters:

• _b (int) – The numerator of the constant expression.
• _c (int) – (optional) The denominator of the constant expression.

Raises:

result.ERROR_INVALID_ARGUMENT in the following cases:

• _b is -2147483648
• _c is -2147483648
• _c is 0

The xform_expr object will be created with xform_expr_mode.PRE.

• For a constant-valued expression, xform_expr_mode.PRE is equivalent to xform_expr_mode.POST and xform_expr_mode.POST_DEREFS_PRE, while xform_expr_mode.POST_DEREFS_PRE_STRICT and xform_expr_mode.POST_STRICT are generally unsuitable since all queries will fail.
• When step_xform.query_bounds() is invoked with a constant-valued xform_expr argument and returns an xform_query_bounds_result object xqbr, the result of xqbr.modified() (xform_query_bounds_result.modified()) is not meaningful.

>>> xform_expr(5,7)
<cs.xform_expr 5 / 7>

>>> xform_expr(5)
<cs.xform_expr 5>

__init__(_base[, _ap = (, )[, _attribute = ""[, _mode =  xform_expr_mode.POST[, _a = 1[, _b = 0[, _c = 1]]]]]])

Constructor for an xform_expr object representing expression (ax + b)/c, where x is an attribute attached to some memory location.

Parameters:

• _base (symbol) – The base for x.
• _ap (iterable of access_path) – (optional) The access path for the memory location of which x is an attribute (based at _base)
• _attribute (str) –

  (optional) The attribute x.

• _mode (xform_expr_mode) – (optional) The temporal mode for evaluation of x.
• _a (int) – (optional) The coefficient a in the expression (ax + b)/c.
• _b (int) – (optional) The constant b in the expression (ax + b)/c.
• _c (int) – (optional) The denominator c in the expression (ax + b)/c.

Raises:

• result.ERROR_INVALID_ARGUMENT in the following cases:

• _a is -2147483648
• _b is -2147483648
• _c is -2147483648
• _c is 0
• _mode is xform_expr_mode.POST_STRICT or xform_expr_mode.POST_DEREFS_PRE_STRICT and _a is 0
• _ap specifies a nonsensical sequence of operators

• result.ERROR_INVALID_ATTRIBUTE if _attribute is not a known attribute.
• result.ERROR_INVALID_OPERATOR if _ap specifies an invalid sequence of operators.
• result.ERROR_PARAMETER_TOO_LARGE if the offset_in_bits field of an offset access_path cannot be represented as a 32-bit signed integer.

Constructs an xform_expr object representing expression (ax + b)/c, where:

• a, b, and c are constants
• x is an attribute of some symbol s
• s is described in terms of its base ( symbol ) and access path ( access_path ).

>>> foo_fn = next(p for p in project.current().procedures() if p.name()=='foo')
>>> foo_s = next(sym for sym in foo_fn.local_symbols() if sym.name()=='s')
>>> xform_expr(foo_s, [access_path.star()], 'fromend', xform_expr_mode.POST, 12, 3, 7)
<cs.xform_expr ( 12 * *s!fromend + 3 ) / 7>

>>> foo_fn = next(p for p in project.current().procedures() if p.name()=='foo')
>>> foo_s = next(sym for sym in foo_fn.local_symbols() if sym.name()=='s')
>>> xform_expr(foo_s, [access_path.star()], 'fromend', xform_expr_mode.POST, 12, 3)
<cs.xform_expr 12 * *s!fromend + 3>

>>> foo_fn = next(p for p in project.current().procedures() if p.name()=='foo')
>>> foo_s = next(sym for sym in foo_fn.local_symbols() if sym.name()=='s')
>>> xform_expr(foo_s, [access_path.star()], 'fromend', xform_expr_mode.POST, 12)
<cs.xform_expr 12 * *s!fromend>

>>> foo_fn = next(p for p in project.current().procedures() if p.name()=='foo')
>>> foo_s = next(sym for sym in foo_fn.local_symbols() if sym.name()=='s')
>>> xform_expr(foo_s, [access_path.star()], 'fromend', xform_expr_mode.POST_STRICT)
<cs.xform_expr *s!fromend>

>>> foo_fn = next(p for p in project.current().procedures() if p.name()=='foo')
>>> foo_s = next(sym for sym in foo_fn.local_symbols() if sym.name()=='s')
>>> xform_expr(foo_s, [access_path.star()], 'fromend')
<cs.xform_expr *s!fromend>

>>> foo_fn = next(p for p in project.current().procedures() if p.name()=='foo')
>>> foo_s = next(sym for sym in foo_fn.local_symbols() if sym.name()=='s')
>>> xform_expr(foo_s, [access_path.star()])
<cs.xform_expr *s>

>>> foo_fn = next(p for p in project.current().procedures() if p.name()=='foo')
>>> foo_s = next(sym for sym in foo_fn.local_symbols() if sym.name()=='s')
>>> xform_expr(foo_s)
<cs.xform_expr s>

__repr__()

Get a representation of a xform_expr object that includes information useful for debugging.

Return type:str Returns:The string representation.

>>> v0 = xform_expr(0)
>>> repr(v0)
'<cs.xform_expr 0>'

__str__()

Get a simple string representation of a xform_expr object.

Return type:str Returns:The string representation.

>>> v0 = xform_expr(0)
>>> str(v0)
'0'