ipcp_bits_lattice Class Reference

#include <ipa-cp.h>

Collaboration diagram for ipcp_bits_lattice:

Public Member Functions
bool	bottom_p () const
bool	top_p () const
bool	constant_p () const
bool	set_to_bottom ()
bool	set_to_constant (widest_int, widest_int)
bool	known_nonzero_p () const
widest_int	get_value () const
widest_int	get_mask () const
bool	meet_with (ipcp_bits_lattice &other, unsigned, signop, enum tree_code, tree, bool)
bool	meet_with (widest_int, widest_int, unsigned)
void	print (FILE *)

Private Types
enum	{ IPA_BITS_UNDEFINED , IPA_BITS_CONSTANT , IPA_BITS_VARYING }

Private Member Functions
bool	meet_with_1 (widest_int, widest_int, unsigned, bool)
void	get_value_and_mask (tree, widest_int *, widest_int *)

Private Attributes
enum ipcp_bits_lattice:: { ... }	m_lattice_val = IPA_BITS_UNDEFINED
widest_int	m_value
widest_int	m_mask

Detailed Description

Lattice of known bits, only capable of holding one value.
Bitwise constant propagation propagates which bits of a
value are constant.
For eg:
int f(int x)
{
  return some_op (x);
}

int f1(int y)
{
  if (cond)
   return f (y & 0xff);
  else
   return f (y & 0xf);
}

In the above case, the param 'x' will always have all
the bits (except the bits in lsb) set to 0.
Hence the mask of 'x' would be 0xff. The mask
reflects that the bits in lsb are unknown.
The actual propagated value is given by m_value & ~m_mask.   

Member Enumeration Documentation

anonymous enum

anonymous enum

private

Enumerator
IPA_BITS_UNDEFINED
IPA_BITS_CONSTANT
IPA_BITS_VARYING

Member Function Documentation

bottom_p()

bool ipcp_bits_lattice::bottom_p ( ) const

inline

References IPA_BITS_VARYING, and m_lattice_val.

Referenced by meet_with(), meet_with(), print(), and set_to_bottom().

constant_p()

bool ipcp_bits_lattice::constant_p ( ) const

inline

References IPA_BITS_CONSTANT, and m_lattice_val.

Referenced by known_nonzero_p(), and meet_with_1().

get_mask()

widest_int ipcp_bits_lattice::get_mask ( ) const

inline

References m_mask.

Referenced by ipcp_store_vr_results(), meet_with(), and print().

get_value()

widest_int ipcp_bits_lattice::get_value ( ) const

inline

References m_value.

Referenced by ipcp_store_vr_results(), meet_with(), and print().

get_value_and_mask()

void ipcp_bits_lattice::get_value_and_mask ( tree operand, widest_int * valuep, widest_int * maskp )

private

Convert operand to value, mask form.   

References get_nonzero_bits(), ggc_alloc(), wi::to_widest(), and TREE_CODE.

Referenced by meet_with().

known_nonzero_p()

bool ipcp_bits_lattice::known_nonzero_p

(

)

const

Return true if any of the known bits are non-zero.   

References wi::bit_and(), wi::bit_not(), constant_p(), m_mask, m_value, and wi::ne_p().

meet_with() [1/2]

bool ipcp_bits_lattice::meet_with	(	ipcp_bits_lattice &	other,
		unsigned	precision,
		signop	sgn,
		enum tree_code	code,
		tree	operand,
		bool	drop_all_ones )

Meet bits lattice with the result of bit_value_binop (other, operand)
if code is binary operation or bit_value_unop (other) if code is unary op.
In the case when code is nop_expr, no adjustment is required.  If
DROP_ALL_ONES, mask out any known bits with value one afterwards.   

References bit_value_binop(), bit_value_unop(), bottom_p(), get_mask(), get_value(), get_value_and_mask(), ggc_alloc(), meet_with_1(), set_to_bottom(), set_to_constant(), wi::sext(), tcc_binary, tcc_unary, top_p(), TREE_CODE_CLASS, TREE_TYPE, TYPE_PRECISION, and TYPE_SIGN.

meet_with() [2/2]

bool ipcp_bits_lattice::meet_with	(	widest_int	value,
		widest_int	mask,
		unsigned	precision )

Meet the bits lattice with operand
described by <value, mask, sgn, precision.   

References bottom_p(), meet_with_1(), set_to_bottom(), set_to_constant(), wi::sext(), and top_p().

meet_with_1()

bool ipcp_bits_lattice::meet_with_1 ( widest_int value, widest_int mask, unsigned precision, bool drop_all_ones )

private

Meet operation, similar to ccp_lattice_meet, we xor values
if this->value, value have different values at same bit positions, we want
to drop that bit to varying. Return true if mask is changed.
This function assumes that the lattice value is in CONSTANT state.  If
DROP_ALL_ONES, mask out any known bits with value one afterwards.   

References constant_p(), gcc_assert, ggc_alloc(), m_mask, m_value, set_to_bottom(), and wi::sext().

Referenced by meet_with(), and meet_with().

print()

void ipcp_bits_lattice::print

(

FILE *

f

)

References bottom_p(), get_mask(), get_value(), ggc_alloc(), print_hex(), and top_p().

set_to_bottom()

bool ipcp_bits_lattice::set_to_bottom

(

)

Set lattice value to bottom, if it already isn't the case.   

References bottom_p(), IPA_BITS_VARYING, m_lattice_val, m_mask, and m_value.

Referenced by meet_with(), meet_with(), and meet_with_1().

set_to_constant()

bool ipcp_bits_lattice::set_to_constant	(	widest_int	value,
		widest_int	mask )

Set to constant if it isn't already. Only meant to be called
when switching state from TOP.   

References wi::bit_and(), wi::bit_not(), gcc_assert, IPA_BITS_CONSTANT, m_lattice_val, m_mask, m_value, and top_p().

Referenced by meet_with(), and meet_with().

top_p()

bool ipcp_bits_lattice::top_p ( ) const

inline

References IPA_BITS_UNDEFINED, and m_lattice_val.

Referenced by meet_with(), meet_with(), print(), and set_to_constant().

Field Documentation

[]

enum { ... } ipcp_bits_lattice::m_lattice_val

Referenced by bottom_p(), constant_p(), set_to_bottom(), set_to_constant(), and top_p().

m_mask

widest_int ipcp_bits_lattice::m_mask

private

Referenced by get_mask(), known_nonzero_p(), meet_with_1(), set_to_bottom(), and set_to_constant().

m_value

widest_int ipcp_bits_lattice::m_value

private

Referenced by get_value(), known_nonzero_p(), meet_with_1(), set_to_bottom(), and set_to_constant().

---

The documentation for this class was generated from the following files:

• ipa-cp.h
• ipa-cp.cc