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/* Dead code elimination pass for the GNU compiler.
Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008
Free Software Foundation, Inc.
Contributed by Ben Elliston <bje@redhat.com>
and Andrew MacLeod <amacleod@redhat.com>
Adapted to use control dependence by Steven Bosscher, SUSE Labs.
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/>. */
/* Dead code elimination.
References:
Building an Optimizing Compiler,
Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
Advanced Compiler Design and Implementation,
Steven Muchnick, Morgan Kaufmann, 1997, Section 18.10.
Dead-code elimination is the removal of statements which have no
impact on the program's output. "Dead statements" have no impact
on the program's output, while "necessary statements" may have
impact on the output.
The algorithm consists of three phases:
1. Marking as necessary all statements known to be necessary,
e.g. most function calls, writing a value to memory, etc;
2. Propagating necessary statements, e.g., the statements
giving values to operands in necessary statements; and
3. Removing dead statements. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "ggc.h"
/* These RTL headers are needed for basic-block.h. */
#include "rtl.h"
#include "tm_p.h"
#include "hard-reg-set.h"
#include "obstack.h"
#include "basic-block.h"
#include "tree.h"
#include "diagnostic.h"
#include "tree-flow.h"
#include "gimple.h"
#include "tree-dump.h"
#include "tree-pass.h"
#include "timevar.h"
#include "flags.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
static struct stmt_stats
{
int total;
int total_phis;
int removed;
int removed_phis;
} stats;
#define STMT_NECESSARY GF_PLF_1
static VEC(gimple,heap) *worklist;
/* Vector indicating an SSA name has already been processed and marked
as necessary. */
static sbitmap processed;
/* Vector indicating that last_stmt if a basic block has already been
marked as necessary. */
static sbitmap last_stmt_necessary;
/* Before we can determine whether a control branch is dead, we need to
compute which blocks are control dependent on which edges.
We expect each block to be control dependent on very few edges so we
use a bitmap for each block recording its edges. An array holds the
bitmap. The Ith bit in the bitmap is set if that block is dependent
on the Ith edge. */
static bitmap *control_dependence_map;
/* Vector indicating that a basic block has already had all the edges
processed that it is control dependent on. */
static sbitmap visited_control_parents;
/* TRUE if this pass alters the CFG (by removing control statements).
FALSE otherwise.
If this pass alters the CFG, then it will arrange for the dominators
to be recomputed. */
static bool cfg_altered;
/* Execute code that follows the macro for each edge (given number
EDGE_NUMBER within the CODE) for which the block with index N is
control dependent. */
#define EXECUTE_IF_CONTROL_DEPENDENT(BI, N, EDGE_NUMBER) \
EXECUTE_IF_SET_IN_BITMAP (control_dependence_map[(N)], 0, \
(EDGE_NUMBER), (BI))
/* Indicate block BB is control dependent on an edge with index EDGE_INDEX. */
static inline void
set_control_dependence_map_bit (basic_block bb, int edge_index)
{
if (bb == ENTRY_BLOCK_PTR)
return;
gcc_assert (bb != EXIT_BLOCK_PTR);
bitmap_set_bit (control_dependence_map[bb->index], edge_index);
}
/* Clear all control dependences for block BB. */
static inline void
clear_control_dependence_bitmap (basic_block bb)
{
bitmap_clear (control_dependence_map[bb->index]);
}
/* Find the immediate postdominator PDOM of the specified basic block BLOCK.
This function is necessary because some blocks have negative numbers. */
static inline basic_block
find_pdom (basic_block block)
{
gcc_assert (block != ENTRY_BLOCK_PTR);
if (block == EXIT_BLOCK_PTR)
return EXIT_BLOCK_PTR;
else
{
basic_block bb = get_immediate_dominator (CDI_POST_DOMINATORS, block);
if (! bb)
return EXIT_BLOCK_PTR;
return bb;
}
}
/* Determine all blocks' control dependences on the given edge with edge_list
EL index EDGE_INDEX, ala Morgan, Section 3.6. */
static void
find_control_dependence (struct edge_list *el, int edge_index)
{
basic_block current_block;
basic_block ending_block;
gcc_assert (INDEX_EDGE_PRED_BB (el, edge_index) != EXIT_BLOCK_PTR);
if (INDEX_EDGE_PRED_BB (el, edge_index) == ENTRY_BLOCK_PTR)
ending_block = single_succ (ENTRY_BLOCK_PTR);
else
ending_block = find_pdom (INDEX_EDGE_PRED_BB (el, edge_index));
for (current_block = INDEX_EDGE_SUCC_BB (el, edge_index);
current_block != ending_block && current_block != EXIT_BLOCK_PTR;
current_block = find_pdom (current_block))
{
edge e = INDEX_EDGE (el, edge_index);
/* For abnormal edges, we don't make current_block control
dependent because instructions that throw are always necessary
anyway. */
if (e->flags & EDGE_ABNORMAL)
continue;
set_control_dependence_map_bit (current_block, edge_index);
}
}
/* Record all blocks' control dependences on all edges in the edge
list EL, ala Morgan, Section 3.6. */
static void
find_all_control_dependences (struct edge_list *el)
{
int i;
for (i = 0; i < NUM_EDGES (el); ++i)
find_control_dependence (el, i);
}
/* If STMT is not already marked necessary, mark it, and add it to the
worklist if ADD_TO_WORKLIST is true. */
static inline void
mark_stmt_necessary (gimple stmt, bool add_to_worklist)
{
gcc_assert (stmt);
if (gimple_plf (stmt, STMT_NECESSARY))
return;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Marking useful stmt: ");
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
fprintf (dump_file, "\n");
}
gimple_set_plf (stmt, STMT_NECESSARY, true);
if (add_to_worklist)
VEC_safe_push (gimple, heap, worklist, stmt);
}
/* Mark the statement defining operand OP as necessary. */
static inline void
mark_operand_necessary (tree op)
{
gimple stmt;
int ver;
gcc_assert (op);
ver = SSA_NAME_VERSION (op);
if (TEST_BIT (processed, ver))
return;
SET_BIT (processed, ver);
stmt = SSA_NAME_DEF_STMT (op);
gcc_assert (stmt);
if (gimple_plf (stmt, STMT_NECESSARY) || gimple_nop_p (stmt))
return;
gimple_set_plf (stmt, STMT_NECESSARY, true);
VEC_safe_push (gimple, heap, worklist, stmt);
}
/* Mark STMT as necessary if it obviously is. Add it to the worklist if
it can make other statements necessary.
If AGGRESSIVE is false, control statements are conservatively marked as
necessary. */
static void
mark_stmt_if_obviously_necessary (gimple stmt, bool aggressive)
{
tree lhs = NULL_TREE;
/* With non-call exceptions, we have to assume that all statements could
throw. If a statement may throw, it is inherently necessary. */
if (flag_non_call_exceptions
&& stmt_could_throw_p (stmt))
{
mark_stmt_necessary (stmt, true);
return;
}
/* Statements that are implicitly live. Most function calls, asm
and return statements are required. Labels and GIMPLE_BIND nodes
are kept because they are control flow, and we have no way of
knowing whether they can be removed. DCE can eliminate all the
other statements in a block, and CFG can then remove the block
and labels. */
switch (gimple_code (stmt))
{
case GIMPLE_PREDICT:
case GIMPLE_LABEL:
mark_stmt_necessary (stmt, false);
return;
case GIMPLE_ASM:
case GIMPLE_RESX:
case GIMPLE_RETURN:
case GIMPLE_CHANGE_DYNAMIC_TYPE:
mark_stmt_necessary (stmt, true);
return;
case GIMPLE_CALL:
/* Most, but not all function calls are required. Function calls that
produce no result and have no side effects (i.e. const pure
functions) are unnecessary. */
if (gimple_has_side_effects (stmt))
{
mark_stmt_necessary (stmt, true);
return;
}
if (!gimple_call_lhs (stmt))
return;
lhs = gimple_call_lhs (stmt);
/* Fall through */
case GIMPLE_ASSIGN:
if (!lhs)
lhs = gimple_assign_lhs (stmt);
/* These values are mildly magic bits of the EH runtime. We can't
see the entire lifetime of these values until landing pads are
generated. */
if (TREE_CODE (lhs) == EXC_PTR_EXPR
|| TREE_CODE (lhs) == FILTER_EXPR)
{
mark_stmt_necessary (stmt, true);
return;
}
break;
case GIMPLE_GOTO:
gcc_assert (!simple_goto_p (stmt));
mark_stmt_necessary (stmt, true);
return;
case GIMPLE_COND:
gcc_assert (EDGE_COUNT (gimple_bb (stmt)->succs) == 2);
/* Fall through. */
case GIMPLE_SWITCH:
if (! aggressive)
mark_stmt_necessary (stmt, true);
break;
default:
break;
}
/* If the statement has volatile operands, it needs to be preserved.
Same for statements that can alter control flow in unpredictable
ways. */
if (gimple_has_volatile_ops (stmt) || is_ctrl_altering_stmt (stmt))
{
mark_stmt_necessary (stmt, true);
return;
}
if (is_hidden_global_store (stmt))
{
mark_stmt_necessary (stmt, true);
return;
}
return;
}
/* Make corresponding control dependent edges necessary. We only
have to do this once for each basic block, so we clear the bitmap
after we're done. */
static void
mark_control_dependent_edges_necessary (basic_block bb, struct edge_list *el)
{
bitmap_iterator bi;
unsigned edge_number;
gcc_assert (bb != EXIT_BLOCK_PTR);
if (bb == ENTRY_BLOCK_PTR)
return;
EXECUTE_IF_CONTROL_DEPENDENT (bi, bb->index, edge_number)
{
gimple stmt;
basic_block cd_bb = INDEX_EDGE_PRED_BB (el, edge_number);
if (TEST_BIT (last_stmt_necessary, cd_bb->index))
continue;
SET_BIT (last_stmt_necessary, cd_bb->index);
stmt = last_stmt (cd_bb);
if (stmt && is_ctrl_stmt (stmt))
mark_stmt_necessary (stmt, true);
}
}
/* Find obviously necessary statements. These are things like most function
calls, and stores to file level variables.
If EL is NULL, control statements are conservatively marked as
necessary. Otherwise it contains the list of edges used by control
dependence analysis. */
static void
find_obviously_necessary_stmts (struct edge_list *el)
{
basic_block bb;
gimple_stmt_iterator gsi;
edge e;
gimple phi, stmt;
FOR_EACH_BB (bb)
{
/* PHI nodes are never inherently necessary. */
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
phi = gsi_stmt (gsi);
gimple_set_plf (phi, STMT_NECESSARY, false);
}
/* Check all statements in the block. */
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
stmt = gsi_stmt (gsi);
gimple_set_plf (stmt, STMT_NECESSARY, false);
mark_stmt_if_obviously_necessary (stmt, el != NULL);
}
}
if (el)
{
/* Prevent the loops from being removed. We must keep the infinite loops,
and we currently do not have a means to recognize the finite ones. */
FOR_EACH_BB (bb)
{
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
if (e->flags & EDGE_DFS_BACK)
mark_control_dependent_edges_necessary (e->dest, el);
}
}
}
/* Propagate necessity using the operands of necessary statements.
Process the uses on each statement in the worklist, and add all
feeding statements which contribute to the calculation of this
value to the worklist.
In conservative mode, EL is NULL. */
static void
propagate_necessity (struct edge_list *el)
{
gimple stmt;
bool aggressive = (el ? true : false);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "\nProcessing worklist:\n");
while (VEC_length (gimple, worklist) > 0)
{
/* Take STMT from worklist. */
stmt = VEC_pop (gimple, worklist);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "processing: ");
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
fprintf (dump_file, "\n");
}
if (aggressive)
{
/* Mark the last statements of the basic blocks that the block
containing STMT is control dependent on, but only if we haven't
already done so. */
basic_block bb = gimple_bb (stmt);
if (bb != ENTRY_BLOCK_PTR
&& ! TEST_BIT (visited_control_parents, bb->index))
{
SET_BIT (visited_control_parents, bb->index);
mark_control_dependent_edges_necessary (bb, el);
}
}
if (gimple_code (stmt) == GIMPLE_PHI)
{
/* PHI nodes are somewhat special in that each PHI alternative has
data and control dependencies. All the statements feeding the
PHI node's arguments are always necessary. In aggressive mode,
we also consider the control dependent edges leading to the
predecessor block associated with each PHI alternative as
necessary. */
size_t k;
for (k = 0; k < gimple_phi_num_args (stmt); k++)
{
tree arg = PHI_ARG_DEF (stmt, k);
if (TREE_CODE (arg) == SSA_NAME)
mark_operand_necessary (arg);
}
if (aggressive)
{
for (k = 0; k < gimple_phi_num_args (stmt); k++)
{
basic_block arg_bb = gimple_phi_arg_edge (stmt, k)->src;
if (arg_bb != ENTRY_BLOCK_PTR
&& ! TEST_BIT (visited_control_parents, arg_bb->index))
{
SET_BIT (visited_control_parents, arg_bb->index);
mark_control_dependent_edges_necessary (arg_bb, el);
}
}
}
}
else
{
/* Propagate through the operands. Examine all the USE, VUSE and
VDEF operands in this statement. Mark all the statements
which feed this statement's uses as necessary. The
operands of VDEF expressions are also needed as they
represent potential definitions that may reach this
statement (VDEF operands allow us to follow def-def
links). */
ssa_op_iter iter;
tree use;
FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES)
mark_operand_necessary (use);
}
}
}
/* Remove dead PHI nodes from block BB. */
static bool
remove_dead_phis (basic_block bb)
{
bool something_changed = false;
gimple_seq phis;
gimple phi;
gimple_stmt_iterator gsi;
phis = phi_nodes (bb);
for (gsi = gsi_start (phis); !gsi_end_p (gsi);)
{
stats.total_phis++;
phi = gsi_stmt (gsi);
if (!gimple_plf (phi, STMT_NECESSARY))
{
something_changed = true;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Deleting : ");
print_gimple_stmt (dump_file, phi, 0, TDF_SLIM);
fprintf (dump_file, "\n");
}
remove_phi_node (&gsi, true);
stats.removed_phis++;
}
else
{
gsi_next (&gsi);
}
}
return something_changed;
}
/* Remove dead statement pointed to by iterator I. Receives the basic block BB
containing I so that we don't have to look it up. */
static void
remove_dead_stmt (gimple_stmt_iterator *i, basic_block bb)
{
gimple stmt = gsi_stmt (*i);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Deleting : ");
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
fprintf (dump_file, "\n");
}
stats.removed++;
/* If we have determined that a conditional branch statement contributes
nothing to the program, then we not only remove it, but we also change
the flow graph so that the current block will simply fall-thru to its
immediate post-dominator. The blocks we are circumventing will be
removed by cleanup_tree_cfg if this change in the flow graph makes them
unreachable. */
if (is_ctrl_stmt (stmt))
{
basic_block post_dom_bb;
/* The post dominance info has to be up-to-date. */
gcc_assert (dom_info_state (CDI_POST_DOMINATORS) == DOM_OK);
/* Get the immediate post dominator of bb. */
post_dom_bb = get_immediate_dominator (CDI_POST_DOMINATORS, bb);
/* There are three particularly problematical cases.
1. Blocks that do not have an immediate post dominator. This
can happen with infinite loops.
2. Blocks that are only post dominated by the exit block. These
can also happen for infinite loops as we create fake edges
in the dominator tree.
3. If the post dominator has PHI nodes we may be able to compute
the right PHI args for them.
In each of these cases we must remove the control statement
as it may reference SSA_NAMEs which are going to be removed and
we remove all but one outgoing edge from the block. */
if (! post_dom_bb
|| post_dom_bb == EXIT_BLOCK_PTR
|| phi_nodes (post_dom_bb))
;
else
{
/* Redirect the first edge out of BB to reach POST_DOM_BB. */
redirect_edge_and_branch (EDGE_SUCC (bb, 0), post_dom_bb);
PENDING_STMT (EDGE_SUCC (bb, 0)) = NULL;
/* It is not sufficient to set cfg_altered below during edge
removal, in case BB has two successors and one of them
is POST_DOM_BB. */
cfg_altered = true;
}
EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
EDGE_SUCC (bb, 0)->count = bb->count;
/* The edge is no longer associated with a conditional, so it does
not have TRUE/FALSE flags. */
EDGE_SUCC (bb, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
/* The lone outgoing edge from BB will be a fallthru edge. */
EDGE_SUCC (bb, 0)->flags |= EDGE_FALLTHRU;
/* Remove the remaining the outgoing edges. */
while (!single_succ_p (bb))
{
/* FIXME. When we remove the edge, we modify the CFG, which
in turn modifies the dominator and post-dominator tree.
Is it safe to postpone recomputing the dominator and
post-dominator tree until the end of this pass given that
the post-dominators are used above? */
cfg_altered = true;
remove_edge (EDGE_SUCC (bb, 1));
}
}
gsi_remove (i, true);
release_defs (stmt);
}
/* Eliminate unnecessary statements. Any instruction not marked as necessary
contributes nothing to the program, and can be deleted. */
static bool
eliminate_unnecessary_stmts (void)
{
bool something_changed = false;
basic_block bb;
gimple_stmt_iterator gsi;
gimple stmt;
tree call;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "\nEliminating unnecessary statements:\n");
clear_special_calls ();
FOR_EACH_BB (bb)
{
/* Remove dead PHI nodes. */
something_changed |= remove_dead_phis (bb);
}
FOR_EACH_BB (bb)
{
/* Remove dead statements. */
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
{
stmt = gsi_stmt (gsi);
stats.total++;
/* If GSI is not necessary then remove it. */
if (!gimple_plf (stmt, STMT_NECESSARY))
{
remove_dead_stmt (&gsi, bb);
something_changed = true;
}
else if (is_gimple_call (stmt))
{
call = gimple_call_fndecl (stmt);
if (call)
{
tree name;
gimple g;
/* When LHS of var = call (); is dead, simplify it into
call (); saving one operand. */
name = gimple_call_lhs (stmt);
if (name && TREE_CODE (name) == SSA_NAME
&& !TEST_BIT (processed, SSA_NAME_VERSION (name)))
{
something_changed = true;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Deleting LHS of call: ");
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
fprintf (dump_file, "\n");
}
push_stmt_changes (gsi_stmt_ptr (&gsi));
g = gimple_copy (stmt);
gimple_call_set_lhs (g, NULL_TREE);
gsi_replace (&gsi, g, false);
maybe_clean_or_replace_eh_stmt (stmt, g);
mark_symbols_for_renaming (g);
pop_stmt_changes (gsi_stmt_ptr (&gsi));
release_ssa_name (name);
}
notice_special_calls (stmt);
}
gsi_next (&gsi);
}
else
{
gsi_next (&gsi);
}
}
}
return something_changed;
}
/* Print out removed statement statistics. */
static void
print_stats (void)
{
float percg;
percg = ((float) stats.removed / (float) stats.total) * 100;
fprintf (dump_file, "Removed %d of %d statements (%d%%)\n",
stats.removed, stats.total, (int) percg);
if (stats.total_phis == 0)
percg = 0;
else
percg = ((float) stats.removed_phis / (float) stats.total_phis) * 100;
fprintf (dump_file, "Removed %d of %d PHI nodes (%d%%)\n",
stats.removed_phis, stats.total_phis, (int) percg);
}
/* Initialization for this pass. Set up the used data structures. */
static void
tree_dce_init (bool aggressive)
{
memset ((void *) &stats, 0, sizeof (stats));
if (aggressive)
{
int i;
control_dependence_map = XNEWVEC (bitmap, last_basic_block);
for (i = 0; i < last_basic_block; ++i)
control_dependence_map[i] = BITMAP_ALLOC (NULL);
last_stmt_necessary = sbitmap_alloc (last_basic_block);
sbitmap_zero (last_stmt_necessary);
}
processed = sbitmap_alloc (num_ssa_names + 1);
sbitmap_zero (processed);
worklist = VEC_alloc (gimple, heap, 64);
cfg_altered = false;
}
/* Cleanup after this pass. */
static void
tree_dce_done (bool aggressive)
{
if (aggressive)
{
int i;
for (i = 0; i < last_basic_block; ++i)
BITMAP_FREE (control_dependence_map[i]);
free (control_dependence_map);
sbitmap_free (visited_control_parents);
sbitmap_free (last_stmt_necessary);
}
sbitmap_free (processed);
VEC_free (gimple, heap, worklist);
}
/* Main routine to eliminate dead code.
AGGRESSIVE controls the aggressiveness of the algorithm.
In conservative mode, we ignore control dependence and simply declare
all but the most trivially dead branches necessary. This mode is fast.
In aggressive mode, control dependences are taken into account, which
results in more dead code elimination, but at the cost of some time.
FIXME: Aggressive mode before PRE doesn't work currently because
the dominance info is not invalidated after DCE1. This is
not an issue right now because we only run aggressive DCE
as the last tree SSA pass, but keep this in mind when you
start experimenting with pass ordering. */
static unsigned int
perform_tree_ssa_dce (bool aggressive)
{
struct edge_list *el = NULL;
bool something_changed = 0;
tree_dce_init (aggressive);
if (aggressive)
{
/* Compute control dependence. */
timevar_push (TV_CONTROL_DEPENDENCES);
calculate_dominance_info (CDI_POST_DOMINATORS);
el = create_edge_list ();
find_all_control_dependences (el);
timevar_pop (TV_CONTROL_DEPENDENCES);
visited_control_parents = sbitmap_alloc (last_basic_block);
sbitmap_zero (visited_control_parents);
mark_dfs_back_edges ();
}
find_obviously_necessary_stmts (el);
propagate_necessity (el);
something_changed |= eliminate_unnecessary_stmts ();
something_changed |= cfg_altered;
/* We do not update postdominators, so free them unconditionally. */
free_dominance_info (CDI_POST_DOMINATORS);
/* If we removed paths in the CFG, then we need to update
dominators as well. I haven't investigated the possibility
of incrementally updating dominators. */
if (cfg_altered)
free_dominance_info (CDI_DOMINATORS);
statistics_counter_event (cfun, "Statements deleted", stats.removed);
statistics_counter_event (cfun, "PHI nodes deleted", stats.removed_phis);
/* Debugging dumps. */
if (dump_file && (dump_flags & (TDF_STATS|TDF_DETAILS)))
print_stats ();
tree_dce_done (aggressive);
free_edge_list (el);
if (something_changed)
return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect
| TODO_remove_unused_locals);
else
return 0;
}
/* Pass entry points. */
static unsigned int
tree_ssa_dce (void)
{
return perform_tree_ssa_dce (/*aggressive=*/false);
}
static unsigned int
tree_ssa_dce_loop (void)
{
unsigned int todo;
todo = perform_tree_ssa_dce (/*aggressive=*/false);
if (todo)
{
free_numbers_of_iterations_estimates ();
scev_reset ();
}
return todo;
}
static unsigned int
tree_ssa_cd_dce (void)
{
return perform_tree_ssa_dce (/*aggressive=*/optimize >= 2);
}
static bool
gate_dce (void)
{
return flag_tree_dce != 0;
}
struct gimple_opt_pass pass_dce =
{
{
GIMPLE_PASS,
"dce", /* name */
gate_dce, /* gate */
tree_ssa_dce, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
TV_TREE_DCE, /* tv_id */
PROP_cfg | PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func | TODO_verify_ssa /* todo_flags_finish */
}
};
struct gimple_opt_pass pass_dce_loop =
{
{
GIMPLE_PASS,
"dceloop", /* name */
gate_dce, /* gate */
tree_ssa_dce_loop, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
TV_TREE_DCE, /* tv_id */
PROP_cfg | PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func | TODO_verify_ssa /* todo_flags_finish */
}
};
struct gimple_opt_pass pass_cd_dce =
{
{
GIMPLE_PASS,
"cddce", /* name */
gate_dce, /* gate */
tree_ssa_cd_dce, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
TV_TREE_CD_DCE, /* tv_id */
PROP_cfg | PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func | TODO_verify_ssa
| TODO_verify_flow /* todo_flags_finish */
}
};
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