GCC Middle and Back End API Reference
prop_value_t Struct Reference

Data Fields

tree value

Detailed Description

Copy propagation and SSA_NAME replacement support routines.
   Copyright (C) 2004-2024 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
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
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

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

◆ value

The documentation for this struct was generated from the following file: