Data Fields | |
| ccp_lattice_t | lattice_val |
| tree | value |
| double_int | mask |
Detailed Description
Copy propagation and SSA_NAME replacement support routines. Copyright (C) 2004-2013 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see http://www.gnu.org/licenses/. This file implements the copy propagation pass and provides a handful of interfaces for performing const/copy propagation and simple expression replacement which keep variable annotations up-to-date.
We require that for any copy operation where the RHS and LHS have a non-null memory tag the memory tag be the same. It is OK for one or both of the memory tags to be NULL.
We also require tracking if a variable is dereferenced in a load or store operation.
We enforce these requirements by having all copy propagation and replacements of one SSA_NAME with a different SSA_NAME to use the APIs defined in this file. Lattice for copy-propagation. The lattice is initialized to UNDEFINED (value == NULL) for SSA names that can become a copy of something or VARYING (value == self) if not (see get_copy_of_val and stmt_may_generate_copy). Other values make the name a COPY of that value.
When visiting a statement or PHI node the lattice value for an SSA name can transition from UNDEFINED to COPY to VARYING.
Field Documentation
| ccp_lattice_t prop_value_d::lattice_val |
Lattice value.
Referenced by bit_value_binop(), get_default_value(), get_value_for_expr(), get_value_from_alignment(), set_lattice_value(), and set_value_varying().
| double_int prop_value_d::mask |
Mask that applies to the propagated value during CCP. For X with a CONSTANT lattice value X & ~mask == value & ~mask.
Referenced by bit_value_binop(), get_default_value(), and get_value_from_alignment().
| tree prop_value_d::value |
Propagated value.
Copy-of value.
Referenced by bit_value_binop(), copy_prop_visit_phi_node(), get_value_from_alignment(), set_value_varying(), and valueize_val().
The documentation for this struct was generated from the following files:
