8sa1-gcc/gcc/tree-ssa-loop-manip.c
Diego Novillo 0bca51f080 backport: copy-prop, incremental SSA updating of FUD chains and newly exposed symbols.
Merge from tree-cleanup-branch: VRP, store CCP, store
	    copy-prop, incremental SSA updating of FUD chains and
	    newly exposed symbols.

	* Makefile.in (tree-ssa-copy.o): Depend on tree-ssa-propagate.h.
	(OBJS-common): Add tree-vrp.o.
	(tree-vrp.o): New rule.
	* basic-block.h (nearest_common_dominator_for_set): Declare.
	* common.opt (ftree-store-ccp): New flag.
	(ftree-copy-prop): New flag.
	(ftree-vrp): New flag.
	(ftree-store-copy-prop): New flag.
	* dominance.c (nearest_common_dominator_for_set): New.
	* domwalk.c (walk_dominator_tree): Only traverse
	statements in blocks marked in walk_data->interesting_blocks.
	* domwalk.h (struct dom_walk_data): Add field interesting_blocks.
	* fold-const.c (fold): Handle ASSERT_EXPR.
	* opts.c (decode_options): Set flag_tree_copy_prop at -O1.
	Set flag_tree_store_ccp, flag_tree_store_copy_prop and
	flag_tree_vrp at -O2.
	* timevar.def (TV_TREE_VRP): Define.
	(TV_TREE_COPY_PROP): Define.
	(TV_TREE_STORE_COPY_PROP): Define.
	(TV_TREE_SSA_INCREMENTAL): Define.
	(TV_TREE_STORE_CCP): Define.
	* tree-cfg.c (tree_can_merge_blocks_p): Remove reference
	to kill_redundant_phi_nodes from comment.
	(verify_expr): Handle ASSERT_EXPR.
	* tree-dfa.c (mark_new_vars_to_rename): Remove second
	argument.  Update all users.
	(mark_call_clobbered_vars_to_rename): Remove.  Update all
	users.
	* tree-flow-inline.h (unmodifiable_var_p): New.
	* tree-flow.h (enum value_range_type): Declare.
	(struct value_range_def): Declare.
	(value_range): Declare.
	(remove_all_phi_nodes_for): Remove.  Update all users.
	(find_phi_node_for): Declare.
	(add_type_alias): Declare.
	(count_uses_and_derefs): Declare.
	(kill_redundant_phi_nodes): Remove.
	(rewrite_into_ssa): Remove.
	(rewrite_def_def_chains): Remove.
	(update_ssa, register_new_name_mapping, create_new_def_for,
	need_ssa_update_p, name_registered_for_update_p,
	release_ssa_name_after_update_ssa, dump_repl_tbl,
	debug_repl_tbl, dump_names_replaced_by,
	debug_names_replaced_by, mark_sym_for_renaming,
	mark_set_for_renaming, get_current_def, set_current_def,
	get_value_range, dump_value_range, debug_value_range,
	dump_all_value_ranges, debug_all_value_ranges,
	expr_computes_nonzero, loop_depth_of_name,
	unmodifiable_var_p): Declare.
	* tree-gimple.c (is_gimple_formal_tmp_rhs): Handle
	ASSERT_EXPR.
	* tree-into-ssa.c (block_defs_stack): Update comment.
	(old_ssa_names, new_ssa_names, old_virtual_ssa_names,
	syms_to_rename, names_to_release, repl_tbl,
	need_to_initialize_update_ssa_p, need_to_update_vops_p,
	need_to_replace_names_p): New locals.
	(NAME_SETS_GROWTH_FACTOR): Define.
	(struct repl_map_d): Declare.
	(struct mark_def_sites_global_data): Add field
	interesting_blocks.
	(enum rewrite_mode): Declare.
	(REGISTER_DEFS_IN_THIS_STMT): Define.
	(compute_global_livein): Use last_basic_block instead of
	n_basic_blocks.
	(set_def_block): Remove last argument.  Update all callers.
	(prepare_use_operand_for_rename): Remove.  Update all callers.
	(prepare_def_operand_for_rename): Remove.  Update all callers.
	(symbol_marked_for_renaming): New.
	(is_old_name): New.
	(is_new_name): New.
	(repl_map_hash): New.
	(repl_map_eq): New.
	(repl_map_free): New.
	(names_replaced_by): New.
	(add_to_repl_tbl): New.
	(add_new_name_mapping): New.
	(mark_def_sites): Assume that all the operands in the
	statement are in normal form.
	(find_idf): Assert that the block in the stack is valid.
	(get_default_def_for): New.
	(insert_phi_nodes_for): Add new argument 'update_p'.
	Add documentation.
	If update_p is true, add a new mapping between the LHS of
	each new PHI and the name that it replaces.
	(insert_phi_nodes_1): Only call find_idf if needed.
	(get_reaching_def): Call get_default_def_for.
	(rewrite_operand): Remove.
	(rewrite_stmt): Do nothing if REGISTER_DEFS_IN_THIS_STMT
	and REWRITE_THIS_STMT are false.
	Assume that all the operands in the statement are in
	normal form.
	(rewrite_add_phi_arguments): Don't use PHI_REWRITTEN.
	(rewrite_virtual_phi_arguments): Remove.
	(invalidate_name_tags): Remove.
	(register_new_update_single, register_new_update_set,
	rewrite_update_init_block, replace_use,
	rewrite_update_fini_block, rewrite_update_stmt,
	rewrite_update_phi_arguments): New.
	rewrite_blocks): Remove argument 'fix_virtual_phis'.
	Add arguments 'entry', 'what' and 'blocks'.
	Initialize the dominator walker according to 'what' and
	'blocks'.
	Start the dominator walk at 'entry'.
	(mark_def_site_blocks): Add argument 'interesting_blocks'.
	Use it to configure the dominator walker.
	(rewrite_into_ssa): Remove argument 'all'.
	Make internal.
	(rewrite_all_into_ssa): Remove.
	(rewrite_def_def_chains): Remove.
	(mark_def_interesting, mark_use_interesting,
	prepare_phi_args_for_update, prepare_block_for_update,
	prepare_def_site_for, prepare_def_sites,
	dump_names_replaced_by, debug_names_replaced_by,
	dump_repl_tbl, debug_repl_tbl, init_update_ssa,
	delete_update_ssa, create_new_def_for,
	register_new_name_mapping, mark_sym_for_renaming,
	mark_set_for_renaming, need_ssa_update_p,
	name_registered_for_update_p, ssa_names_to_replace,
	release_ssa_name_after_update_ssa,
	insert_updated_phi_nodes_for, update_ssa): New.
	* tree-loop-linear.c (linear_transform_loops): Call
	update_ssa instead of rewrite_into_ssa.
	* tree-optimize.c (vars_to_rename): Remove.
	Update all users.
	(init_tree_optimization_passes): Replace
	pass_redundant_phi with pass_copy_prop.
	Add pass_vrp.
	Replace pass_ccp with pass_store_ccp.
	Add pass_store_copy_prop after pass_store_ccp.
	(execute_todo): If the TODO_ flags don't include updating
	the SSA form, assert that it does not need to be updated.
	Call update_ssa instead of rewrite_into_ssa and
	rewrite_def_def_chains.
	If TODO_verify_loops is set, call verify_loop_closed_ssa.
	(tree_rest_of_compilation):
	* tree-pass.h (TODO_dump_func, TODO_ggc_collect,
	TODO_verify_ssa, TODO_verify_flow, TODO_verify_stmts,
	TODO_cleanup_cfg): Renumber.
	(TODO_verify_loops, TODO_update_ssa,
	TODO_update_ssa_no_phi, TODO_update_ssa_full_phi,
	TODO_update_ssa_only_virtuals): Define.
	(pass_copy_prop, pass_store_ccp, pass_store_copy_prop, pass_vrp):
	Declare.
	* tree-phinodes.c (make_phi_node): Update documentation.
	(remove_all_phi_nodes_for): Remove.
	(find_phi_node_for): New.
	* tree-pretty-print.c (dump_generic_node): Handle ASSERT_EXPR.
	* tree-scalar-evolution.c (follow_ssa_edge_in_rhs): Likewise.
	(interpret_rhs_modify_expr): Likewise.
	* tree-sra.c (decide_instantiations): Mark all symbols in
	SRA_CANDIDATES for renaming.
	(mark_all_v_defs_1): Rename from mark_all_v_defs.
	(mark_all_v_defs): New function.  Update all users to call it
	with the whole list of scalarized statements, not just the
	first one.
	* tree-ssa-alias.c (count_ptr_derefs): Make extern.
	(compute_flow_insensitive_aliasing): If the tag is
	unmodifiable and the variable isn't or vice-versa, don't
	make them alias of each other.
	(setup_pointers_and_addressables): If the type tag for
	VAR is about to change, mark the old one for renaming.
	(add_type_alias): New.
	* tree-ssa-ccp.c: Document SSA-CCP and STORE-CCP.
	(ccp_lattice_t): Rename from latticevalue.
	(value): Remove.  Update all users.
	(const_val): New local variable.
	(do_store_ccp): New local variable.
	(dump_lattice_value): Handle UNINITIALIZED.
	(debug_lattice_value): New.
	(get_default_value): Re-write.
	(set_lattice_value): Re-write.
	(def_to_varying): Remove.  Update all users.
	(likely_value): Return VARYING for statements that make
	stores when STORE_CCP is false.
	Return VARYING for any statement other than MODIFY_EXPR,
	COND_EXPR and SWITCH_EXPR.
	(ccp_initialize): Re-write.
	(replace_uses_in, replace_vuse_in, substitute_and_fold):
	Move to tree-ssa-propagate.c.
	(ccp_lattice_meet): Handle memory stores when
	DO_STORE_CCP is true.
	(ccp_visit_phi_node): Likewise.
	(ccp_fold): Likewise.
	(evaluate_stmt): Likewise.
	(visit_assignment): Likewise.
	(ccp_visit_stmt): Likewise.
	(execute_ssa_ccp): Add argument 'store_ccp'.  Copy it
	into DO_STORE_CCP.
	(do_ssa_ccp): New.
	(pass_ccp): Use it.
	(do_ssa_store_ccp): New.
	(gate_store_ccp): New.
	(pass_store_ccp): Declare.
	* tree-ssa-copy.c: Include tree-ssa-propagate.h.
	(may_propagate_copy): Reformat.
	Don't abort if ORIG is a virtual and DEST isn't.
	If NEW does not have alias information but DEST does,
	copy it.
	(copy_of, cached_last_copy_of, do_store_copy_prop, enum
	copy_prop_kind, which_copy_prop): Declare.
	(stmt_may_generate_copy, get_copy_of_val,
	get_last_copy_of, set_copy_of_val, dump_copy_of,
	copy_prop_visit_assignment, copy_prop_visit_cond_stmt,
	copy_prop_visit_stmt, copy_prop_visit_phi_node,
	init_copy_prop, fini_copy_prop, execute_copy_prop,
	gate_copy_prop, do_copy_prop, gate_store_copy_prop,
	store_copy_prop): New.
	(pass_copy_prop, pass_store_copy_prop): Declare.
	* tree-ssa-dom.c (struct opt_stats_d): Add fields
	'num_const_prop' and 'num_copy_prop'.
	(cprop_operand): Update them.
	(dump_dominator_optimization_stats): Dump them.
	(tree_ssa_dominator_optimize): Call update_ssa instead of
	rewrite_into_ssa.
	(loop_depth_of_name): Declare extern.
	(simplify_cond_and_lookup_avail_expr): Guard against NULL
	values for LOW or HIGH.
	(cprop_into_successor_phis): Only propagate if NEW != ORIG.
	(record_equivalences_from_stmt): Call expr_computes_nonzero.
	(cprop_operand): Only propagate if VAL != OP.
	* tree-ssa-dse.c (dse_optimize_stmt): Mark symbols in removed
	statement for renaming.
	* tree-ssa-loop-im.c (move_computations): Call update_ssa.
	* tree-ssa-loop-ivopts.c (rewrite_address_base): Call
	add_type_alias if necessary.
	Call mark_new_vars_to_rename.
	(tree_ssa_iv_optimize): If new symbols need to be renamed,
	mark every statement updated, call update_ssa and
	rewrite_into_loop_closed_ssa.
	* tree-ssa-loop-manip.c (add_exit_phis): Do not remove DEF_BB
	from LIVEIN if VAR is a virtual.
	* tree-ssa-loop.c (tree_loop_optimizer_init): Call update_ssa.
	* tree-ssa-operands.c (get_expr_operands): Handle ASSERT_EXPR.
	(get_call_expr_operands): Reformat statement.
	(add_stmt_operand): Don't create V_MAY_DEFs for read-only
	symbols.
	* tree-ssa-propagate.c (ssa_prop_init): Initialize
	SSA_NAME_VALUE for every name.
	(first_vdef, stmt_makes_single_load, stmt_makes_single_store,
	get_value_loaded_by): New.
	(replace_uses_in, replace_vuses_in, replace_phi_args_in,
	substitute_and_fold): Move from tree-ssa-ccp.c.
	* tree-ssa-propagate.h (struct prop_value_d, prop_value_t,
	first_vdef, stmt_makes_single_load, stmt_makes_single_store,
	get_value_loaded_by, replace_uses_in, substitute_and_fold):
	Declare.
	* tree-ssa.c (verify_use): Fix error message.
	(propagate_into_addr, replace_immediate_uses, get_eq_name,
	check_phi_redundancy, kill_redundant_phi_nodes,
	pass_redundant_phi): Remove.  Update all users.
	* tree-vect-transform.c (vect_create_data_ref_ptr): Call
	add_type_alias, if necessary.
	* tree-vectorizer.h (struct _stmt_vect_info): Update
	documentation for field 'memtag'.
	* tree-vrp.c: New file.
	* tree.def (ASSERT_EXPR): Define.
	* tree.h (ASSERT_EXPR_VAR): Define.
	(ASSERT_EXPR_COND): Define.
	(SSA_NAME_VALUE_RANGE): Define.
	(struct tree_ssa_name): Add field 'value_range'.
	(PHI_REWRITTEN): Remove.
	(struct tree_phi_node): Remove field 'rewritten'.
	* doc/invoke.texi (-fdump-tree-storeccp, -ftree-copy-prop,
	-ftree-store-copy-prop): Document.
	* doc/tree-ssa.texi: Remove broken link to McCAT's compiler.
	Document usage of update_ssa.

testsuite/ChangeLog

	* g++.dg/tree-ssa/pr18178.C: New test.
	* gcc.c-torture/execute/20030216-1.x: Ignore at -O1.
	* gcc.c-torture/execute/20041019-1.c: New test.
	* gcc.dg/tree-ssa/20041008-1.c: New test.
	* gcc.dg/tree-ssa/ssa-ccp-12.c: New test.
	* gcc.dg/tree-ssa/20030731-2.c: Update to use -fdump-tree-store_ccp.
	* gcc.dg/tree-ssa/20030917-1.c: Likewise.
	* gcc.dg/tree-ssa/20030917-3.c: Likewise.
	* gcc.dg/tree-ssa/20040721-1.c: Likewise.
	* gcc.dg/tree-ssa/ssa-ccp-1.c: Likewise.
	* gcc.dg/tree-ssa/ssa-ccp-2.c: Likewise.
	* gcc.dg/tree-ssa/ssa-ccp-3.c: Likewise.
	* gcc.dg/tree-ssa/ssa-ccp-7.c: Likewise.
	* gcc.dg/tree-ssa/ssa-ccp-9.c: Likewise.

From-SVN: r97884
2005-04-08 21:37:54 -04:00

683 lines
18 KiB
C

/* High-level loop manipulation functions.
Copyright (C) 2004, 2005 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 2, 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 COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "tm_p.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "output.h"
#include "diagnostic.h"
#include "tree-flow.h"
#include "tree-dump.h"
#include "timevar.h"
#include "cfgloop.h"
#include "tree-pass.h"
#include "cfglayout.h"
#include "tree-scalar-evolution.h"
/* Creates an induction variable with value BASE + STEP * iteration in LOOP.
It is expected that neither BASE nor STEP are shared with other expressions
(unless the sharing rules allow this). Use VAR as a base var_decl for it
(if NULL, a new temporary will be created). The increment will occur at
INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and
AFTER can be computed using standard_iv_increment_position. The ssa versions
of the variable before and after increment will be stored in VAR_BEFORE and
VAR_AFTER (unless they are NULL). */
void
create_iv (tree base, tree step, tree var, struct loop *loop,
block_stmt_iterator *incr_pos, bool after,
tree *var_before, tree *var_after)
{
tree stmt, initial, step1, stmts;
tree vb, va;
enum tree_code incr_op = PLUS_EXPR;
if (!var)
{
var = create_tmp_var (TREE_TYPE (base), "ivtmp");
add_referenced_tmp_var (var);
}
vb = make_ssa_name (var, NULL_TREE);
if (var_before)
*var_before = vb;
va = make_ssa_name (var, NULL_TREE);
if (var_after)
*var_after = va;
/* For easier readability of the created code, produce MINUS_EXPRs
when suitable. */
if (TREE_CODE (step) == INTEGER_CST)
{
if (TYPE_UNSIGNED (TREE_TYPE (step)))
{
step1 = fold (build1 (NEGATE_EXPR, TREE_TYPE (step), step));
if (tree_int_cst_lt (step1, step))
{
incr_op = MINUS_EXPR;
step = step1;
}
}
else
{
if (!tree_expr_nonnegative_p (step)
&& may_negate_without_overflow_p (step))
{
incr_op = MINUS_EXPR;
step = fold (build1 (NEGATE_EXPR, TREE_TYPE (step), step));
}
}
}
stmt = build2 (MODIFY_EXPR, void_type_node, va,
build2 (incr_op, TREE_TYPE (base),
vb, step));
SSA_NAME_DEF_STMT (va) = stmt;
if (after)
bsi_insert_after (incr_pos, stmt, BSI_NEW_STMT);
else
bsi_insert_before (incr_pos, stmt, BSI_NEW_STMT);
initial = force_gimple_operand (base, &stmts, true, var);
if (stmts)
{
edge pe = loop_preheader_edge (loop);
bsi_insert_on_edge_immediate_loop (pe, stmts);
}
stmt = create_phi_node (vb, loop->header);
SSA_NAME_DEF_STMT (vb) = stmt;
add_phi_arg (stmt, initial, loop_preheader_edge (loop));
add_phi_arg (stmt, va, loop_latch_edge (loop));
}
/* Add exit phis for the USE on EXIT. */
static void
add_exit_phis_edge (basic_block exit, tree use)
{
tree phi, def_stmt = SSA_NAME_DEF_STMT (use);
basic_block def_bb = bb_for_stmt (def_stmt);
struct loop *def_loop;
edge e;
edge_iterator ei;
/* Check that some of the edges entering the EXIT block exits a loop in
that USE is defined. */
FOR_EACH_EDGE (e, ei, exit->preds)
{
def_loop = find_common_loop (def_bb->loop_father, e->src->loop_father);
if (!flow_bb_inside_loop_p (def_loop, e->dest))
break;
}
if (!e)
return;
phi = create_phi_node (use, exit);
FOR_EACH_EDGE (e, ei, exit->preds)
add_phi_arg (phi, use, e);
SSA_NAME_DEF_STMT (use) = def_stmt;
}
/* Add exit phis for VAR that is used in LIVEIN.
Exits of the loops are stored in EXITS. */
static void
add_exit_phis_var (tree var, bitmap livein, bitmap exits)
{
bitmap def;
unsigned index;
basic_block def_bb = bb_for_stmt (SSA_NAME_DEF_STMT (var));
bitmap_iterator bi;
if (is_gimple_reg (var))
bitmap_clear_bit (livein, def_bb->index);
else
bitmap_set_bit (livein, def_bb->index);
def = BITMAP_ALLOC (NULL);
bitmap_set_bit (def, def_bb->index);
compute_global_livein (livein, def);
BITMAP_FREE (def);
EXECUTE_IF_AND_IN_BITMAP (exits, livein, 0, index, bi)
{
add_exit_phis_edge (BASIC_BLOCK (index), var);
}
}
/* Add exit phis for the names marked in NAMES_TO_RENAME.
Exits of the loops are stored in EXITS. Sets of blocks where the ssa
names are used are stored in USE_BLOCKS. */
static void
add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap loop_exits)
{
unsigned i;
bitmap_iterator bi;
EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i, bi)
{
add_exit_phis_var (ssa_name (i), use_blocks[i], loop_exits);
}
}
/* Returns a bitmap of all loop exit edge targets. */
static bitmap
get_loops_exits (void)
{
bitmap exits = BITMAP_ALLOC (NULL);
basic_block bb;
edge e;
edge_iterator ei;
FOR_EACH_BB (bb)
{
FOR_EACH_EDGE (e, ei, bb->preds)
if (e->src != ENTRY_BLOCK_PTR
&& !flow_bb_inside_loop_p (e->src->loop_father, bb))
{
bitmap_set_bit (exits, bb->index);
break;
}
}
return exits;
}
/* For USE in BB, if it is used outside of the loop it is defined in,
mark it for rewrite. Record basic block BB where it is used
to USE_BLOCKS. */
static void
find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks)
{
unsigned ver;
basic_block def_bb;
struct loop *def_loop;
if (TREE_CODE (use) != SSA_NAME)
return;
ver = SSA_NAME_VERSION (use);
def_bb = bb_for_stmt (SSA_NAME_DEF_STMT (use));
if (!def_bb)
return;
def_loop = def_bb->loop_father;
/* If the definition is not inside loop, it is not interesting. */
if (!def_loop->outer)
return;
if (!use_blocks[ver])
use_blocks[ver] = BITMAP_ALLOC (NULL);
bitmap_set_bit (use_blocks[ver], bb->index);
if (!flow_bb_inside_loop_p (def_loop, bb))
mark_for_rewrite (use);
}
/* For uses in STMT, mark names that are used outside of the loop they are
defined to rewrite. Record the set of blocks in that the ssa
names are defined to USE_BLOCKS. */
static void
find_uses_to_rename_stmt (tree stmt, bitmap *use_blocks)
{
ssa_op_iter iter;
tree var;
basic_block bb = bb_for_stmt (stmt);
get_stmt_operands (stmt);
FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_ALL_USES | SSA_OP_ALL_KILLS)
find_uses_to_rename_use (bb, var, use_blocks);
}
/* Marks names that are used in BB and outside of the loop they are
defined in for rewrite. Records the set of blocks in that the ssa
names are defined to USE_BLOCKS. */
static void
find_uses_to_rename_bb (basic_block bb, bitmap *use_blocks)
{
block_stmt_iterator bsi;
edge e;
edge_iterator ei;
tree phi;
FOR_EACH_EDGE (e, ei, bb->succs)
for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
find_uses_to_rename_use (bb, PHI_ARG_DEF_FROM_EDGE (phi, e),
use_blocks);
for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
find_uses_to_rename_stmt (bsi_stmt (bsi), use_blocks);
}
/* Marks names that are used outside of the loop they are defined in
for rewrite. Records the set of blocks in that the ssa
names are defined to USE_BLOCKS. If CHANGED_BBS is not NULL,
scan only blocks in this set. */
static void
find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks)
{
basic_block bb;
unsigned index;
bitmap_iterator bi;
if (changed_bbs)
{
EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi)
{
find_uses_to_rename_bb (BASIC_BLOCK (index), use_blocks);
}
}
else
{
FOR_EACH_BB (bb)
{
find_uses_to_rename_bb (bb, use_blocks);
}
}
}
/* Rewrites the program into a loop closed ssa form -- i.e. inserts extra
phi nodes to ensure that no variable is used outside the loop it is
defined in.
This strengthening of the basic ssa form has several advantages:
1) Updating it during unrolling/peeling/versioning is trivial, since
we do not need to care about the uses outside of the loop.
2) The behavior of all uses of an induction variable is the same.
Without this, you need to distinguish the case when the variable
is used outside of the loop it is defined in, for example
for (i = 0; i < 100; i++)
{
for (j = 0; j < 100; j++)
{
k = i + j;
use1 (k);
}
use2 (k);
}
Looking from the outer loop with the normal SSA form, the first use of k
is not well-behaved, while the second one is an induction variable with
base 99 and step 1.
If CHANGED_BBS is not NULL, we look for uses outside loops only in
the basic blocks in this set. */
void
rewrite_into_loop_closed_ssa (bitmap changed_bbs)
{
bitmap loop_exits = get_loops_exits ();
bitmap *use_blocks;
unsigned i;
bitmap names_to_rename;
gcc_assert (!any_marked_for_rewrite_p ());
use_blocks = xcalloc (num_ssa_names, sizeof (bitmap));
/* Find the uses outside loops. */
find_uses_to_rename (changed_bbs, use_blocks);
if (!any_marked_for_rewrite_p ())
{
free (use_blocks);
BITMAP_FREE (loop_exits);
return;
}
/* Add the phi nodes on exits of the loops for the names we need to
rewrite. */
names_to_rename = marked_ssa_names ();
add_exit_phis (names_to_rename, use_blocks, loop_exits);
for (i = 0; i < num_ssa_names; i++)
BITMAP_FREE (use_blocks[i]);
free (use_blocks);
BITMAP_FREE (loop_exits);
BITMAP_FREE (names_to_rename);
/* Do the rewriting. */
rewrite_ssa_into_ssa ();
}
/* Check invariants of the loop closed ssa form for the USE in BB. */
static void
check_loop_closed_ssa_use (basic_block bb, tree use)
{
tree def;
basic_block def_bb;
if (TREE_CODE (use) != SSA_NAME)
return;
def = SSA_NAME_DEF_STMT (use);
def_bb = bb_for_stmt (def);
gcc_assert (!def_bb
|| flow_bb_inside_loop_p (def_bb->loop_father, bb));
}
/* Checks invariants of loop closed ssa form in statement STMT in BB. */
static void
check_loop_closed_ssa_stmt (basic_block bb, tree stmt)
{
ssa_op_iter iter;
tree var;
get_stmt_operands (stmt);
FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_ALL_USES)
check_loop_closed_ssa_use (bb, var);
}
/* Checks that invariants of the loop closed ssa form are preserved. */
void
verify_loop_closed_ssa (void)
{
basic_block bb;
block_stmt_iterator bsi;
tree phi;
unsigned i;
verify_ssa (false);
FOR_EACH_BB (bb)
{
for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
for (i = 0; i < (unsigned) PHI_NUM_ARGS (phi); i++)
check_loop_closed_ssa_use (PHI_ARG_EDGE (phi, i)->src,
PHI_ARG_DEF (phi, i));
for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
check_loop_closed_ssa_stmt (bb, bsi_stmt (bsi));
}
}
/* Split loop exit edge EXIT. The things are a bit complicated by a need to
preserve the loop closed ssa form. */
void
split_loop_exit_edge (edge exit)
{
basic_block dest = exit->dest;
basic_block bb = loop_split_edge_with (exit, NULL);
tree phi, new_phi, new_name, name;
use_operand_p op_p;
for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
{
op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, single_succ_edge (bb));
name = USE_FROM_PTR (op_p);
/* If the argument of the phi node is a constant, we do not need
to keep it inside loop. */
if (TREE_CODE (name) != SSA_NAME)
continue;
/* Otherwise create an auxiliary phi node that will copy the value
of the ssa name out of the loop. */
new_name = duplicate_ssa_name (name, NULL);
new_phi = create_phi_node (new_name, bb);
SSA_NAME_DEF_STMT (new_name) = new_phi;
add_phi_arg (new_phi, name, exit);
SET_USE (op_p, new_name);
}
}
/* Insert statement STMT to the edge E and update the loop structures.
Returns the newly created block (if any). */
basic_block
bsi_insert_on_edge_immediate_loop (edge e, tree stmt)
{
basic_block src, dest, new_bb;
struct loop *loop_c;
src = e->src;
dest = e->dest;
loop_c = find_common_loop (src->loop_father, dest->loop_father);
new_bb = bsi_insert_on_edge_immediate (e, stmt);
if (!new_bb)
return NULL;
add_bb_to_loop (new_bb, loop_c);
if (dest->loop_father->latch == src)
dest->loop_father->latch = new_bb;
return new_bb;
}
/* Returns the basic block in that statements should be emitted for induction
variables incremented at the end of the LOOP. */
basic_block
ip_end_pos (struct loop *loop)
{
return loop->latch;
}
/* Returns the basic block in that statements should be emitted for induction
variables incremented just before exit condition of a LOOP. */
basic_block
ip_normal_pos (struct loop *loop)
{
tree last;
basic_block bb;
edge exit;
if (!single_pred_p (loop->latch))
return NULL;
bb = single_pred (loop->latch);
last = last_stmt (bb);
if (TREE_CODE (last) != COND_EXPR)
return NULL;
exit = EDGE_SUCC (bb, 0);
if (exit->dest == loop->latch)
exit = EDGE_SUCC (bb, 1);
if (flow_bb_inside_loop_p (loop, exit->dest))
return NULL;
return bb;
}
/* Stores the standard position for induction variable increment in LOOP
(just before the exit condition if it is available and latch block is empty,
end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if
the increment should be inserted after *BSI. */
void
standard_iv_increment_position (struct loop *loop, block_stmt_iterator *bsi,
bool *insert_after)
{
basic_block bb = ip_normal_pos (loop), latch = ip_end_pos (loop);
tree last = last_stmt (latch);
if (!bb
|| (last && TREE_CODE (last) != LABEL_EXPR))
{
*bsi = bsi_last (latch);
*insert_after = true;
}
else
{
*bsi = bsi_last (bb);
*insert_after = false;
}
}
/* Copies phi node arguments for duplicated blocks. The index of the first
duplicated block is FIRST_NEW_BLOCK. */
static void
copy_phi_node_args (unsigned first_new_block)
{
unsigned i;
for (i = first_new_block; i < (unsigned) last_basic_block; i++)
BASIC_BLOCK (i)->rbi->duplicated = 1;
for (i = first_new_block; i < (unsigned) last_basic_block; i++)
add_phi_args_after_copy_bb (BASIC_BLOCK (i));
for (i = first_new_block; i < (unsigned) last_basic_block; i++)
BASIC_BLOCK (i)->rbi->duplicated = 0;
}
/* Renames variables in the area copied by tree_duplicate_loop_to_header_edge.
FIRST_NEW_BLOCK is the first block in the copied area. DEFINITIONS is
a bitmap of all ssa names defined inside the loop. */
static void
rename_variables (unsigned first_new_block, bitmap definitions)
{
unsigned i, copy_number = 0;
basic_block bb;
htab_t ssa_name_map = NULL;
for (i = first_new_block; i < (unsigned) last_basic_block; i++)
{
bb = BASIC_BLOCK (i);
/* We assume that first come all blocks from the first copy, then all
blocks from the second copy, etc. */
if (copy_number != (unsigned) bb->rbi->copy_number)
{
allocate_ssa_names (definitions, &ssa_name_map);
copy_number = bb->rbi->copy_number;
}
rewrite_to_new_ssa_names_bb (bb, ssa_name_map);
}
htab_delete (ssa_name_map);
}
/* Sets SSA_NAME_DEF_STMT for results of all phi nodes in BB. */
static void
set_phi_def_stmts (basic_block bb)
{
tree phi;
for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
SSA_NAME_DEF_STMT (PHI_RESULT (phi)) = phi;
}
/* The same as cfgloopmanip.c:duplicate_loop_to_header_edge, but also updates
ssa. In order to achieve this, only loops whose exits all lead to the same
location are handled.
FIXME: we create some degenerate phi nodes that could be avoided by copy
propagating them instead. Unfortunately this is not completely
straightforward due to problems with constant folding. */
bool
tree_duplicate_loop_to_header_edge (struct loop *loop, edge e,
struct loops *loops,
unsigned int ndupl, sbitmap wont_exit,
edge orig, edge *to_remove,
unsigned int *n_to_remove, int flags)
{
unsigned first_new_block;
basic_block bb;
unsigned i;
bitmap definitions;
if (!(loops->state & LOOPS_HAVE_SIMPLE_LATCHES))
return false;
if (!(loops->state & LOOPS_HAVE_PREHEADERS))
return false;
#ifdef ENABLE_CHECKING
verify_loop_closed_ssa ();
#endif
gcc_assert (!any_marked_for_rewrite_p ());
first_new_block = last_basic_block;
if (!duplicate_loop_to_header_edge (loop, e, loops, ndupl, wont_exit,
orig, to_remove, n_to_remove, flags))
return false;
/* Readd the removed phi args for e. */
flush_pending_stmts (e);
/* Copy the phi node arguments. */
copy_phi_node_args (first_new_block);
/* Rename the variables. */
definitions = marked_ssa_names ();
rename_variables (first_new_block, definitions);
unmark_all_for_rewrite ();
BITMAP_FREE (definitions);
/* For some time we have the identical ssa names as results in multiple phi
nodes. When phi node is resized, it sets SSA_NAME_DEF_STMT of its result
to the new copy. This means that we cannot easily ensure that the ssa
names defined in those phis are pointing to the right one -- so just
recompute SSA_NAME_DEF_STMT for them. */
for (i = first_new_block; i < (unsigned) last_basic_block; i++)
{
bb = BASIC_BLOCK (i);
set_phi_def_stmts (bb);
if (bb->rbi->copy_number == 1)
set_phi_def_stmts (bb->rbi->original);
}
scev_reset ();
#ifdef ENABLE_CHECKING
verify_loop_closed_ssa ();
#endif
return true;
}