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Use simple_dce_from_worklist with match_simplify_replacement.

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This is a simple patch to do some DCE after a successful
match and simplify replacement in PHI-OPT. match and simplify
likes to generate some extra statements which should be cleaned
up.

OK? Bootstrapped and tested on x86_64-linux with no regressions.

Thanks,
Andrew Pinski

gcc/ChangeLog:

	* tree-ssa-phiopt.cc: Include tree-ssa-dce.h
	(replace_phi_edge_with_variable):
	New argument, dce_ssa_names. Call simple_dce_from_worklist.
	(match_simplify_replacement): If we inserted a sequence,
	mark the lhs of the new sequence to be possible dce.
	Always move the statement and mark the lhs (if it is a name)
	as possible to remove.
This commit is contained in:
Andrew Pinski 2022-10-27 04:37:01 +00:00
parent a33d623d2d
commit 1c2b53ce8b
1 changed files with 26 additions and 9 deletions
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35
gcc/tree-ssa-phiopt.cc
View file

@ -53,6 +53,7 @@ along with GCC; see the file COPYING3. If not see
#include "gimple-match.h"
#include "dbgcnt.h"
#include "tree-ssa-propagate.h"
#include "tree-ssa-dce.h"
static unsigned int tree_ssa_phiopt_worker (bool, bool, bool);
static bool two_value_replacement (basic_block, basic_block, edge, gphi *,
@ -74,7 +75,6 @@ static bool cond_store_replacement (basic_block, basic_block, edge, edge,
hash_set<tree> *);
static bool cond_if_else_store_replacement (basic_block, basic_block, basic_block);
static hash_set<tree> * get_non_trapping ();
static void replace_phi_edge_with_variable (basic_block, edge, gphi *, tree);
static void hoist_adjacent_loads (basic_block, basic_block,
basic_block, basic_block);
static bool gate_hoist_loads (void);
@ -402,7 +402,8 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
static void
replace_phi_edge_with_variable (basic_block cond_block,
edge e, gphi *phi, tree new_tree)
edge e, gphi *phi, tree new_tree,
bitmap dce_ssa_names = auto_bitmap())
{
basic_block bb = gimple_bb (phi);
gimple_stmt_iterator gsi;
@ -477,6 +478,8 @@ replace_phi_edge_with_variable (basic_block cond_block,
gimple_cond_make_true (cond);
}
simple_dce_from_worklist (dce_ssa_names);
statistics_counter_event (cfun, "Replace PHI with variable", 1);
if (dump_file && (dump_flags & TDF_DETAILS))
@ -986,6 +989,7 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
gimple_seq seq = NULL;
tree result;
gimple *stmt_to_move = NULL;
auto_bitmap inserted_exprs;
/* Special case A ? B : B as this will always simplify to B. */
if (operand_equal_for_phi_arg_p (arg0, arg1))
@ -1060,14 +1064,22 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
gsi = gsi_last_bb (cond_bb);
/* Insert the sequence generated from gimple_simplify_phiopt. */
if (seq)
{
// Mark the lhs of the new statements maybe for dce
gimple_stmt_iterator gsi1 = gsi_start (seq);
for (; !gsi_end_p (gsi1); gsi_next (&gsi1))
{
gimple *stmt = gsi_stmt (gsi1);
tree name = gimple_get_lhs (stmt);
if (name && TREE_CODE (name) == SSA_NAME)
bitmap_set_bit (inserted_exprs, SSA_NAME_VERSION (name));
}
gsi_insert_seq_before (&gsi, seq, GSI_CONTINUE_LINKING);
}
/* If there was a statement to move and the result of the statement
is going to be used, move it to right before the original
conditional. */
if (stmt_to_move
&& (gimple_assign_lhs (stmt_to_move) == result
|| !has_single_use (gimple_assign_lhs (stmt_to_move))))
/* If there was a statement to move, move it to right before
the original conditional. */
if (stmt_to_move)
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
@ -1075,12 +1087,17 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
print_gimple_stmt (dump_file, stmt_to_move, 0,
TDF_VOPS|TDF_MEMSYMS);
}
tree name = gimple_get_lhs (stmt_to_move);
// Mark the name to be renamed if there is one.
if (name && TREE_CODE (name) == SSA_NAME)
bitmap_set_bit (inserted_exprs, SSA_NAME_VERSION (name));
gimple_stmt_iterator gsi1 = gsi_for_stmt (stmt_to_move);
gsi_move_before (&gsi1, &gsi);
reset_flow_sensitive_info (gimple_assign_lhs (stmt_to_move));
}
replace_phi_edge_with_variable (cond_bb, e1, phi, result);
replace_phi_edge_with_variable (cond_bb, e1, phi, result, inserted_exprs);
/* Add Statistic here even though replace_phi_edge_with_variable already
does it as we want to be able to count when match-simplify happens vs