Collaboration diagram for st_expr:

Data Fields
rtx	pattern

vec< rtx >	pattern_regs

vec< rtx_insn * >	antic_stores

vec< rtx_insn * >	avail_stores

struct st_expr *	next

int	index

unsigned int	hash_index

rtx	reaching_reg

Detailed Description

Store motion via Lazy Code Motion on the reverse CFG.
   Copyright (C) 1997-2024 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
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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 pass implements downward store motion.
As of May 1, 2009, the pass is not enabled by default on any target,
but bootstrap completes on ia64 and x86_64 with the pass enabled.

TODO:
  - remove_reachable_equiv_notes is an incomprehensible pile of goo and
    a compile time hog that needs a rewrite (maybe cache st_exprs to
    invalidate REG_EQUAL/REG_EQUIV notes for?).
  - pattern_regs in st_expr should be a regset (on its own obstack).
  - store_motion_mems should be a vec instead of a list.
  - there should be an alloc pool for struct st_expr objects.
  - investigate whether it is helpful to make the address of an st_expr
    a cselib VALUE.
  - when GIMPLE alias information is exported, the effectiveness of this
    pass should be re-evaluated.

This is a list of store expressions (MEMs).  The structure is used
as an expression table to track stores which look interesting, and
might be moveable towards the exit block.