fwprop.cc File Reference

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "rtl.h"
#include "rtlanal.h"
#include "df.h"
#include "rtl-ssa.h"
#include "predict.h"
#include "cfgrtl.h"
#include "cfgcleanup.h"
#include "cfgloop.h"
#include "tree-pass.h"
#include "rtl-iter.h"
#include "target.h"

Include dependency graph for fwprop.cc:

Macros
#define	INCLUDE_ALGORITHM
#define	INCLUDE_FUNCTIONAL

Functions
static bool	can_simplify_addr (rtx addr)
static bool	should_replace_address (int old_num_changes, rtx mem, rtx_insn *insn)
static bool	reg_single_def_p (rtx x)
static int	try_fwprop_subst_note (insn_info *use_insn, set_info *def, rtx note, rtx dest, rtx src, bool require_constant)
static bool	try_fwprop_subst_pattern (obstack_watermark &attempt, insn_change &use_change, set_info *def, rtx *loc, rtx dest, rtx src)
static bool	try_fwprop_subst_notes (insn_info *use_insn, set_info *def, rtx dest, rtx src)
static bool	try_fwprop_subst (use_info *use, set_info *def, rtx *loc, rtx dest, rtx src)
static bool	free_load_extend (rtx src, insn_info *insn)
static bool	forward_propagate_subreg (use_info *use, set_info *def, rtx dest, rtx src, df_ref ref)
static bool	forward_propagate_subreg (use_info *use, set_info *def, rtx dest, rtx src)
static bool	forward_propagate_and_simplify (use_info *use, set_info *def, rtx dest, rtx src)
static bool	forward_propagate_into (use_info *use, bool reg_prop_only=false)
static void	fwprop_init (void)
static void	fwprop_done (void)
static bool	fwprop_insn (insn_info *insn, bool fwprop_addr_p)
static bool	gate_fwprop (void)
static unsigned int	fwprop (bool fwprop_addr_p)
rtl_opt_pass *	make_pass_rtl_fwprop (gcc::context *ctxt)
rtl_opt_pass *	make_pass_rtl_fwprop_addr (gcc::context *ctxt)

Variables
static int	num_changes

Macro Definition Documentation

INCLUDE_ALGORITHM

#define INCLUDE_ALGORITHM

RTL-based forward propagation pass for GNU compiler.
   Copyright (C) 2005-2024 Free Software Foundation, Inc.
   Contributed by Paolo Bonzini and Steven Bosscher.

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/>.   

INCLUDE_FUNCTIONAL

#define INCLUDE_FUNCTIONAL

Function Documentation

can_simplify_addr()

static bool can_simplify_addr ( rtx addr )

static

Do not try to replace constant addresses or addresses of local and
argument slots.  These MEM expressions are made only once and inserted
in many instructions, as well as being used to control symbol table
output.  It is not safe to clobber them.

There are some uncommon cases where the address is already in a register
for some reason, but we cannot take advantage of that because we have
no easy way to unshare the MEM.  In addition, looking up all stack
addresses is costly.   

References CONSTANT_ADDRESS_P, GET_CODE, ggc_alloc(), HARD_FRAME_POINTER_REGNUM, REG_P, REGNO, and XEXP.

forward_propagate_and_simplify()

static bool forward_propagate_and_simplify ( use_info * use, set_info * def, rtx dest, rtx src )

static

Try to substitute (set DEST SRC), which defines DEF, into USE and
simplify the result.   

References avoid_constant_pool_reference(), contains_paradoxical_subreg_p(), copy_rtx(), find_reg_note(), GET_MODE, ggc_alloc(), use::insn, MEM_P, MEM_READONLY_P, NULL_RTX, PATTERN(), REG_P, SET_DEST, set_for_reg_notes(), SET_SRC, set_unique_reg_note(), simplify_replace_rtx(), single_set(), try_fwprop_subst(), and XEXP.

Referenced by forward_propagate_into().

forward_propagate_into()

static bool forward_propagate_into ( use_info * use, bool reg_prop_only = false )

static

Given a use USE of an insn, if it has a single reaching
definition, try to forward propagate it into that insn.
Return true if something changed.

REG_PROP_ONLY is true if we should only propagate register copies.   

References find_reg_note(), flow_loop_nested_p(), forward_propagate_and_simplify(), forward_propagate_subreg(), ggc_alloc(), use::insn, JUMP_P, multiple_sets(), NONJUMP_INSN_P, NULL_RTX, PATTERN(), reg_single_def_p(), SET_DEST, SET_SRC, simple_regno_set(), and volatile_refs_p().

Referenced by fwprop_insn().

forward_propagate_subreg() [1/2]

static bool forward_propagate_subreg ( use_info * use, set_info * def, rtx dest, rtx src )

static

Try to substitute (set DEST SRC), which defines DEF, into USE and simplify
the result, handling cases where DEST is used in a subreg and where
applying that subreg to SRC results in a useful simplification.   

References DF_REF_REGNO, FOR_EACH_INSN_EQ_USE, FOR_EACH_INSN_USE, forward_propagate_subreg(), GET_CODE, ggc_alloc(), use::insn, and REG_P.

forward_propagate_subreg() [2/2]

static bool forward_propagate_subreg ( use_info * use, set_info * def, rtx dest, rtx src, df_ref ref )

static

Subroutine of forward_propagate_subreg that handles a use of DEST
in REF.  The other parameters are the same.   

References DF_REF_LOC, DF_REF_REG, free_load_extend(), GET_CODE, GET_MODE, ggc_alloc(), paradoxical_subreg_p(), REG_P, REGNO, subreg_lowpart_p(), SUBREG_REG, targetm, try_fwprop_subst(), use_reg(), and XEXP.

Referenced by forward_propagate_into(), and forward_propagate_subreg().

free_load_extend()

static bool free_load_extend ( rtx src, insn_info * insn )

static

For the given single_set INSN, containing SRC known to be a
ZERO_EXTEND or SIGN_EXTEND of a register, return true if INSN
is redundant due to the register being set by a LOAD_EXTEND_OP
load from memory.   

References GET_CODE, GET_MODE, ggc_alloc(), load_extend_op(), NONJUMP_INSN_P, PATTERN(), REGNO, rtx_equal_p(), SET, SET_DEST, SET_SRC, and XEXP.

Referenced by forward_propagate_subreg().

fwprop()

static unsigned int fwprop ( bool fwprop_addr_p )

static

References crtl, fwprop_done(), fwprop_init(), fwprop_insn(), ggc_alloc(), i, and worklist.

fwprop_done()

static void fwprop_done ( void )

static

References CDI_DOMINATORS, cleanup_cfg(), crtl, delete_trivially_dead_insns(), dump_file, free_dominance_info(), get_insns(), ggc_alloc(), loop_optimizer_finalize(), max_reg_num(), and num_changes.

Referenced by fwprop().

fwprop_init()

static void fwprop_init ( void )

static

References AVOID_CFG_MODIFICATIONS, calculate_dominance_info(), CDI_DOMINATORS, cfun, crtl, df_analyze(), loop_optimizer_init(), and num_changes.

Referenced by fwprop().

fwprop_insn()

static bool fwprop_insn ( insn_info * insn, bool fwprop_addr_p )

static

Try to optimize INSN, returning true if something changes.
FWPROP_ADDR_P is true if we are running fwprop_addr rather than
the full fwprop.   

References forward_propagate_into(), ggc_alloc(), loop_outer(), and NULL.

Referenced by fwprop().

gate_fwprop()

static bool gate_fwprop ( void )

static

Main entry point.   

References ggc_alloc().

make_pass_rtl_fwprop()

rtl_opt_pass * make_pass_rtl_fwprop

(

gcc::context *

ctxt

)

References ggc_alloc().

make_pass_rtl_fwprop_addr()

rtl_opt_pass * make_pass_rtl_fwprop_addr

(

gcc::context *

ctxt

)

References ggc_alloc().

reg_single_def_p()

static bool reg_single_def_p ( rtx x )

static

Check that X has a single def.   

References crtl, REG_P, and REGNO.

Referenced by forward_propagate_into().

should_replace_address()

static bool should_replace_address ( int old_num_changes, rtx mem, rtx_insn * insn )

static

MEM is the result of an address simplification, and temporarily
undoing changes OLD_NUM_CHANGES onwards restores the original address.
Return whether it is good to use the new address instead of the
old one.  INSN is the containing instruction.   

References address_cost(), BLOCK_FOR_INSN(), GET_MODE, ggc_alloc(), MEM_ADDR_SPACE, optimize_bb_for_speed_p(), redo_changes(), set_src_cost(), temporarily_undo_changes(), and XEXP.

try_fwprop_subst()

static bool try_fwprop_subst ( use_info * use, set_info * def, rtx * loc, rtx dest, rtx src )

static

Check whether we could validly substitute (set DEST SRC), which defines DEF,
into USE.  If so, first try performing the substitution in location LOC
of USE->insn ()'s pattern.  If that fails, try instead to substitute
into the notes.

Return true on success, otherwise leave USE_INSN unchanged.   

References crtl, ggc_alloc(), HARD_REGISTER_P, use::insn, REG_P, try_fwprop_subst_notes(), and try_fwprop_subst_pattern().

Referenced by forward_propagate_and_simplify(), and forward_propagate_subreg().

try_fwprop_subst_note()

static int try_fwprop_subst_note ( insn_info * use_insn, set_info * def, rtx note, rtx dest, rtx src, bool require_constant )

static

Try to substitute (set DEST SRC), which defines DEF, into note NOTE of
USE_INSN.  Return the number of substitutions on success, otherwise return
-1 and leave USE_INSN unchanged.

If REQUIRE_CONSTANT is true, require all substituted occurrences of SRC
to fold to a constant, so that the note does not use any more registers
than it did previously.  If REQUIRE_CONSTANT is false, also allow the
substitution if it's something we'd normally allow for the main
instruction pattern.   

References dump_file, dump_flags, ggc_alloc(), INSN_UID(), print_inline_rtx(), redo_changes(), TDF_DETAILS, temporarily_undo_changes(), and XEXP.

Referenced by try_fwprop_subst_notes(), and try_fwprop_subst_pattern().

try_fwprop_subst_notes()

static bool try_fwprop_subst_notes ( insn_info * use_insn, set_info * def, rtx dest, rtx src )

static

Try to substitute (set DEST SRC), which defines DEF, into USE_INSN's notes,
given that it was not possible to do this for USE_INSN's main pattern.
Return true on success, otherwise leave USE_INSN unchanged.   

References confirm_change_group(), ggc_alloc(), REG_NOTE_KIND, REG_NOTES, try_fwprop_subst_note(), and XEXP.

Referenced by try_fwprop_subst().

try_fwprop_subst_pattern()

static bool try_fwprop_subst_pattern ( obstack_watermark & attempt, insn_change & use_change, set_info * def, rtx * loc, rtx dest, rtx src )

static

Try to substitute (set DEST SRC), which defines DEF, into location LOC of
USE_INSN's pattern.  Return true on success, otherwise leave USE_INSN
unchanged.   

References BLOCK_FOR_INSN(), cancel_changes(), confirm_change_group(), contains_mem_rtx_p(), contains_paradoxical_subreg_p(), copy_rtx(), crtl, dump_file, dump_flags, find_reg_note(), free_EXPR_LIST_node(), GET_MODE, ggc_alloc(), NULL_RTX, num_changes, optimize_bb_for_speed_p(), PATTERN(), print_rtl_single(), recog(), redo_changes(), REG_NOTE_KIND, REG_NOTES, REG_P, SET_DEST, set_for_reg_notes(), SET_SRC, set_src_cost(), set_unique_reg_note(), single_set(), TDF_DETAILS, temporarily_undo_changes(), try_fwprop_subst_note(), and XEXP.

Referenced by try_fwprop_subst().

Variable Documentation

num_changes

int num_changes

static

Referenced by insn_propagation::apply_to_pattern(), insn_propagation::apply_to_rvalue(), insn_propagation::apply_to_rvalue_1(), fwprop_done(), fwprop_init(), and try_fwprop_subst_pattern().