static void
process_replaceable (temp_expr_table_p tab, gimple stmt)
{
tree var, def, basevar;
int version;
ssa_op_iter iter;
bitmap def_vars, use_vars;
#ifdef ENABLE_CHECKING
gcc_assert (is_replaceable_p (stmt));
#endif
def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
version = SSA_NAME_VERSION (def);
basevar = SSA_NAME_VAR (def);
def_vars = BITMAP_ALLOC (NULL);
bitmap_set_bit (def_vars, DECL_UID (basevar));
/* Add this expression to the dependency list for each use partition. */
FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
{
int var_version = SSA_NAME_VERSION (var);
use_vars = tab->expr_decl_uids[var_version];
add_dependence (tab, version, var);
if (use_vars)
{
bitmap_ior_into (def_vars, use_vars);
BITMAP_FREE (tab->expr_decl_uids[var_version]);
}
else
bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var)));
}
void
set_ssa_name_value (tree name, tree value)
{
if (SSA_NAME_VERSION (name) >= ssa_name_values.length ())
ssa_name_values.safe_grow_cleared (SSA_NAME_VERSION (name) + 1);
ssa_name_values[SSA_NAME_VERSION (name)] = value;
}
void
set_ssa_name_value (tree name, tree value)
{
if (SSA_NAME_VERSION (name) >= VEC_length (tree, ssa_name_values))
VEC_safe_grow_cleared (tree, heap, ssa_name_values,
SSA_NAME_VERSION (name) + 1);
VEC_replace (tree, ssa_name_values, SSA_NAME_VERSION (name), value);
}
tree
make_ssa_name_fn (struct function *fn, tree var, gimple stmt)
{
tree t;
use_operand_p imm;
gcc_assert (TREE_CODE (var) == VAR_DECL
|| TREE_CODE (var) == PARM_DECL
|| TREE_CODE (var) == RESULT_DECL
|| (TYPE_P (var) && is_gimple_reg_type (var)));
/* If our free list has an element, then use it. */
if (!vec_safe_is_empty (FREE_SSANAMES (fn)))
{
t = FREE_SSANAMES (fn)->pop ();
if (GATHER_STATISTICS)
ssa_name_nodes_reused++;
/* The node was cleared out when we put it on the free list, so
there is no need to do so again here. */
gcc_assert (ssa_name (SSA_NAME_VERSION (t)) == NULL);
(*SSANAMES (fn))[SSA_NAME_VERSION (t)] = t;
}
else
{
t = make_node (SSA_NAME);
SSA_NAME_VERSION (t) = SSANAMES (fn)->length ();
vec_safe_push (SSANAMES (fn), t);
if (GATHER_STATISTICS)
ssa_name_nodes_created++;
}
if (TYPE_P (var))
{
TREE_TYPE (t) = var;
SET_SSA_NAME_VAR_OR_IDENTIFIER (t, NULL_TREE);
}
else
{
TREE_TYPE (t) = TREE_TYPE (var);
SET_SSA_NAME_VAR_OR_IDENTIFIER (t, var);
}
SSA_NAME_DEF_STMT (t) = stmt;
if (POINTER_TYPE_P (TREE_TYPE (t)))
SSA_NAME_PTR_INFO (t) = NULL;
else
SSA_NAME_RANGE_INFO (t) = NULL;
SSA_NAME_IN_FREE_LIST (t) = 0;
SSA_NAME_IS_DEFAULT_DEF (t) = 0;
imm = &(SSA_NAME_IMM_USE_NODE (t));
imm->use = NULL;
imm->prev = imm;
imm->next = imm;
imm->loc.ssa_name = t;
return t;
}
void
set_ssa_name_value (tree name, tree value)
{
if (SSA_NAME_VERSION (name) >= ssa_name_values.length ())
ssa_name_values.safe_grow_cleared (SSA_NAME_VERSION (name) + 1);
if (value && TREE_OVERFLOW_P (value))
value = drop_tree_overflow (value);
ssa_name_values[SSA_NAME_VERSION (name)] = value;
}
static tree
get_value (tree name)
{
tree val;
if (SSA_NAME_VERSION (name) >= n_copy_of)
return NULL_TREE;
val = copy_of[SSA_NAME_VERSION (name)].value;
if (val && val != name)
return val;
return NULL_TREE;
}
tree
make_ssa_name (tree var, tree stmt)
{
tree t;
use_operand_p imm;
gcc_assert (DECL_P (var)
|| TREE_CODE (var) == INDIRECT_REF);
gcc_assert (!stmt
|| EXPR_P (stmt) || GIMPLE_STMT_P (stmt)
|| TREE_CODE (stmt) == PHI_NODE);
/* If our free list has an element, then use it. */
if (FREE_SSANAMES (cfun))
{
t = FREE_SSANAMES (cfun);
FREE_SSANAMES (cfun) = TREE_CHAIN (FREE_SSANAMES (cfun));
#ifdef GATHER_STATISTICS
ssa_name_nodes_reused++;
#endif
/* The node was cleared out when we put it on the free list, so
there is no need to do so again here. */
gcc_assert (ssa_name (SSA_NAME_VERSION (t)) == NULL);
VEC_replace (tree, SSANAMES (cfun), SSA_NAME_VERSION (t), t);
}
else
{
t = make_node (SSA_NAME);
SSA_NAME_VERSION (t) = num_ssa_names;
VEC_safe_push (tree, gc, SSANAMES (cfun), t);
#ifdef GATHER_STATISTICS
ssa_name_nodes_created++;
#endif
}
TREE_TYPE (t) = TREE_TYPE (var);
SSA_NAME_VAR (t) = var;
SSA_NAME_DEF_STMT (t) = stmt;
SSA_NAME_PTR_INFO (t) = NULL;
SSA_NAME_IN_FREE_LIST (t) = 0;
SSA_NAME_IS_DEFAULT_DEF (t) = 0;
imm = &(SSA_NAME_IMM_USE_NODE (t));
imm->use = NULL;
imm->prev = imm;
imm->next = imm;
imm->stmt = t;
return t;
}
static bool
sese_bad_liveouts_use (sese region, bitmap liveouts, basic_block bb,
tree use)
{
unsigned ver;
basic_block def_bb;
if (TREE_CODE (use) != SSA_NAME)
return false;
ver = SSA_NAME_VERSION (use);
/* If it's in liveouts, the variable will get a new PHI node, and
the debug use will be properly adjusted. */
if (bitmap_bit_p (liveouts, ver))
return false;
def_bb = gimple_bb (SSA_NAME_DEF_STMT (use));
if (!def_bb
|| !bb_in_sese_p (def_bb, region)
|| bb_in_sese_p (bb, region))
return false;
return true;
}
static tree
get_last_copy_of (tree var)
{
tree last;
int i;
/* Traverse COPY_OF starting at VAR until we get to the last
link in the chain. Since it is possible to have cycles in PHI
nodes, the copy-of chain may also contain cycles.
To avoid infinite loops and to avoid traversing lengthy copy-of
chains, we artificially limit the maximum number of chains we are
willing to traverse.
The value 5 was taken from a compiler and runtime library
bootstrap and a mixture of C and C++ code from various sources.
More than 82% of all copy-of chains were shorter than 5 links. */
#define LIMIT 5
last = var;
for (i = 0; i < LIMIT; i++)
{
tree copy = copy_of[SSA_NAME_VERSION (last)].value;
if (copy == NULL_TREE || copy == last)
break;
last = copy;
}
/* If we have reached the limit, then we are either in a copy-of
cycle or the copy-of chain is too long. In this case, just
return VAR so that it is not considered a copy of anything. */
return (i < LIMIT ? last : var);
}
static inline bool
set_copy_of_val (tree dest, tree first)
{
unsigned int dest_ver = SSA_NAME_VERSION (dest);
tree old_first, old_last, new_last;
/* Set FIRST to be the first link in COPY_OF[DEST]. If that
changed, return true. */
old_first = copy_of[dest_ver].value;
copy_of[dest_ver].value = first;
if (old_first != first)
return true;
/* If FIRST and OLD_FIRST are the same, we need to check whether the
copy-of chain starting at FIRST ends in a different variable. If
the copy-of chain starting at FIRST ends up in a different
variable than the last cached value we had for DEST, then return
true because DEST is now a copy of a different variable.
This test is necessary because even though the first link in the
copy-of chain may not have changed, if any of the variables in
the copy-of chain changed its final value, DEST will now be the
copy of a different variable, so we have to do another round of
propagation for everything that depends on DEST. */
old_last = cached_last_copy_of[dest_ver];
new_last = get_last_copy_of (dest);
cached_last_copy_of[dest_ver] = new_last;
return (old_last != new_last);
}
static void
dump_copy_of (FILE *file, tree var)
{
tree val;
print_generic_expr (file, var, dump_flags);
if (TREE_CODE (var) != SSA_NAME)
return;
val = copy_of[SSA_NAME_VERSION (var)].value;
fprintf (file, " copy-of chain: ");
print_generic_expr (file, var, 0);
fprintf (file, " ");
if (!val)
fprintf (file, "[UNDEFINED]");
else if (val == var)
fprintf (file, "[NOT A COPY]");
else
{
fprintf (file, "-> ");
print_generic_expr (file, val, 0);
fprintf (file, " ");
fprintf (file, "[COPY]");
}
}
/* Return SSA names that are unused to GGC memory and compact the SSA
version namespace. This is used to keep footprint of compiler during
interprocedural optimization. */
static unsigned int
release_dead_ssa_names (void)
{
unsigned i, j;
int n = vec_safe_length (FREE_SSANAMES (cfun));
/* Now release the freelist. */
vec_free (FREE_SSANAMES (cfun));
/* And compact the SSA number space. We make sure to not change the
relative order of SSA versions. */
for (i = 1, j = 1; i < cfun->gimple_df->ssa_names->length (); ++i)
{
tree name = ssa_name (i);
if (name)
{
if (i != j)
{
SSA_NAME_VERSION (name) = j;
(*cfun->gimple_df->ssa_names)[j] = name;
}
j++;
}
}
cfun->gimple_df->ssa_names->truncate (j);
statistics_counter_event (cfun, "SSA names released", n);
statistics_counter_event (cfun, "SSA name holes removed", i - j);
if (dump_file)
fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
n, n * 100.0 / num_ssa_names, i - j);
return 0;
}
tree
make_ssa_name_fn (struct function *fn, tree var, gimple stmt)
{
tree t;
use_operand_p imm;
gcc_assert (DECL_P (var));
/* If our free list has an element, then use it. */
if (FREE_SSANAMES (fn))
{
t = FREE_SSANAMES (fn);
FREE_SSANAMES (fn) = TREE_CHAIN (FREE_SSANAMES (fn));
#ifdef GATHER_STATISTICS
ssa_name_nodes_reused++;
#endif
/* The node was cleared out when we put it on the free list, so
there is no need to do so again here. */
gcc_assert (ssa_name (SSA_NAME_VERSION (t)) == NULL);
VEC_replace (tree, SSANAMES (fn), SSA_NAME_VERSION (t), t);
}
else
{
t = make_node (SSA_NAME);
SSA_NAME_VERSION (t) = VEC_length (tree, SSANAMES (fn));
VEC_safe_push (tree, gc, SSANAMES (fn), t);
#ifdef GATHER_STATISTICS
ssa_name_nodes_created++;
#endif
}
TREE_TYPE (t) = TREE_TYPE (var);
SSA_NAME_VAR (t) = var;
SSA_NAME_DEF_STMT (t) = stmt;
SSA_NAME_PTR_INFO (t) = NULL;
SSA_NAME_IN_FREE_LIST (t) = 0;
SSA_NAME_IS_DEFAULT_DEF (t) = 0;
imm = &(SSA_NAME_IMM_USE_NODE (t));
imm->use = NULL;
imm->prev = imm;
imm->next = imm;
imm->loc.ssa_name = t;
return t;
}
static unsigned
get_stmt_uid (tree stmt)
{
if (TREE_CODE (stmt) == PHI_NODE)
return SSA_NAME_VERSION (PHI_RESULT (stmt)) + max_stmt_uid;
return stmt_ann (stmt)->uid;
}
static unsigned
get_stmt_uid (gimple stmt)
{
if (gimple_code (stmt) == GIMPLE_PHI)
return SSA_NAME_VERSION (gimple_phi_result (stmt))
+ gimple_stmt_max_uid (cfun);
return gimple_uid (stmt);
}
static void
init_parameter_lattice_values (void)
{
tree parm, ssa_name;
for (parm = DECL_ARGUMENTS (cfun->decl); parm ; parm = DECL_CHAIN (parm))
if (is_complex_reg (parm)
&& (ssa_name = ssa_default_def (cfun, parm)) != NULL_TREE)
complex_lattice_values[SSA_NAME_VERSION (ssa_name)] = VARYING;
}
static void
dump_copy_of (FILE *file, tree var)
{
tree val;
sbitmap visited;
print_generic_expr (file, var, dump_flags);
if (TREE_CODE (var) != SSA_NAME)
return;
visited = sbitmap_alloc (num_ssa_names);
sbitmap_zero (visited);
SET_BIT (visited, SSA_NAME_VERSION (var));
fprintf (file, " copy-of chain: ");
val = var;
print_generic_expr (file, val, 0);
fprintf (file, " ");
while (copy_of[SSA_NAME_VERSION (val)].value)
{
fprintf (file, "-> ");
val = copy_of[SSA_NAME_VERSION (val)].value;
print_generic_expr (file, val, 0);
fprintf (file, " ");
if (TEST_BIT (visited, SSA_NAME_VERSION (val)))
break;
SET_BIT (visited, SSA_NAME_VERSION (val));
}
val = get_copy_of_val (var)->value;
if (val == NULL_TREE)
fprintf (file, "[UNDEFINED]");
else if (val != var)
fprintf (file, "[COPY]");
else
fprintf (file, "[NOT A COPY]");
sbitmap_free (visited);
}
DEBUG_FUNCTION void
verify_ssaname_freelists (struct function *fun)
{
if (!gimple_in_ssa_p (fun))
return;
bitmap names_in_il = BITMAP_ALLOC (NULL);
/* Walk the entire IL noting every SSA_NAME we see. */
basic_block bb;
FOR_EACH_BB_FN (bb, fun)
{
tree t;
/* First note the result and arguments of PHI nodes. */
for (gphi_iterator gsi = gsi_start_phis (bb);
!gsi_end_p (gsi);
gsi_next (&gsi))
{
gphi *phi = gsi.phi ();
t = gimple_phi_result (phi);
bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
for (unsigned int i = 0; i < gimple_phi_num_args (phi); i++)
{
t = gimple_phi_arg_def (phi, i);
if (TREE_CODE (t) == SSA_NAME)
bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
}
}
/* Then note the operands of each statement. */
for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
!gsi_end_p (gsi);
gsi_next (&gsi))
{
ssa_op_iter iter;
gimple *stmt = gsi_stmt (gsi);
FOR_EACH_SSA_TREE_OPERAND (t, stmt, iter, SSA_OP_ALL_OPERANDS)
bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
}
}
/* qsort comparison function to sort operand entries PA and PB by rank
so that the sorted array is ordered by rank in decreasing order. */
static int
sort_by_operand_rank (const void *pa, const void *pb)
{
const operand_entry_t oea = *(const operand_entry_t *)pa;
const operand_entry_t oeb = *(const operand_entry_t *)pb;
/* It's nicer for optimize_expression if constants that are likely
to fold when added/multiplied//whatever are put next to each
other. Since all constants have rank 0, order them by type. */
if (oeb->rank == 0 && oea->rank == 0)
return constant_type (oeb->op) - constant_type (oea->op);
/* Lastly, make sure the versions that are the same go next to each
other. We use SSA_NAME_VERSION because it's stable. */
if ((oeb->rank - oea->rank == 0)
&& TREE_CODE (oea->op) == SSA_NAME
&& TREE_CODE (oeb->op) == SSA_NAME)
return SSA_NAME_VERSION (oeb->op) - SSA_NAME_VERSION (oea->op);
return oeb->rank - oea->rank;
}
static void
init_parameter_lattice_values (void)
{
tree parm, ssa_name;
for (parm = DECL_ARGUMENTS (cfun->decl); parm ; parm = TREE_CHAIN (parm))
if (is_complex_reg (parm)
&& var_ann (parm) != NULL
&& (ssa_name = gimple_default_def (cfun, parm)) != NULL_TREE)
VEC_replace (complex_lattice_t, complex_lattice_values,
SSA_NAME_VERSION (ssa_name), VARYING);
}
static bool
verify_def (basic_block bb, basic_block *definition_block, tree ssa_name,
tree stmt, bool is_virtual)
{
if (verify_ssa_name (ssa_name, is_virtual))
goto err;
if (definition_block[SSA_NAME_VERSION (ssa_name)])
{
error ("SSA_NAME created in two different blocks %i and %i",
definition_block[SSA_NAME_VERSION (ssa_name)]->index, bb->index);
goto err;
}
definition_block[SSA_NAME_VERSION (ssa_name)] = bb;
if (SSA_NAME_DEF_STMT (ssa_name) != stmt)
{
error ("SSA_NAME_DEF_STMT is wrong");
fprintf (stderr, "Expected definition statement:\n");
print_generic_stmt (stderr, SSA_NAME_DEF_STMT (ssa_name), TDF_VOPS);
fprintf (stderr, "\nActual definition statement:\n");
print_generic_stmt (stderr, stmt, TDF_VOPS);
goto err;
}
return false;
err:
fprintf (stderr, "while verifying SSA_NAME ");
print_generic_expr (stderr, ssa_name, 0);
fprintf (stderr, " in statement\n");
print_generic_stmt (stderr, stmt, TDF_VOPS);
return true;
}
static inline prop_value_t *
get_copy_of_val (tree var)
{
prop_value_t *val = ©_of[SSA_NAME_VERSION (var)];
if (val->value == NULL_TREE
&& !stmt_may_generate_copy (SSA_NAME_DEF_STMT (var)))
{
/* If the variable will never generate a useful copy relation,
make it its own copy. */
val->value = var;
}
return val;
}
static void
output_phi (struct output_block *ob, gimple phi)
{
unsigned i, len = gimple_phi_num_args (phi);
streamer_write_record_start (ob, lto_gimple_code_to_tag (GIMPLE_PHI));
streamer_write_uhwi (ob, SSA_NAME_VERSION (PHI_RESULT (phi)));
for (i = 0; i < len; i++)
{
stream_write_tree (ob, gimple_phi_arg_def (phi, i), true);
streamer_write_uhwi (ob, gimple_phi_arg_edge (phi, i)->src->index);
lto_output_location (ob, gimple_phi_arg_location (phi, i));
}
}
static inline bool
set_copy_of_val (tree var, tree val)
{
unsigned int ver = SSA_NAME_VERSION (var);
tree old;
/* Set FIRST to be the first link in COPY_OF[DEST]. If that
changed, return true. */
old = copy_of[ver].value;
copy_of[ver].value = val;
if (old != val
|| (val && !operand_equal_p (old, val, 0)))
return true;
return false;
}
static void
add_dependence (temp_expr_table_p tab, int version, tree var)
{
int i;
bitmap_iterator bi;
unsigned x;
i = SSA_NAME_VERSION (var);
if (version_to_be_replaced_p (tab, i))
{
if (!bitmap_empty_p (tab->new_replaceable_dependencies))
{
/* Version will now be killed by a write to any partition the
substituted expression would have been killed by. */
EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi)
add_to_partition_kill_list (tab, x, version);
/* Rather than set partition_dependencies and in_use lists bit by
bit, simply OR in the new_replaceable_dependencies bits. */
if (!tab->partition_dependencies[version])
tab->partition_dependencies[version] = BITMAP_ALLOC (NULL);
bitmap_ior_into (tab->partition_dependencies[version],
tab->new_replaceable_dependencies);
bitmap_ior_into (tab->partition_in_use,
tab->new_replaceable_dependencies);
/* It is only necessary to add these once. */
bitmap_clear (tab->new_replaceable_dependencies);
}
}
else
{
i = var_to_partition (tab->map, var);
#ifdef ENABLE_CHECKING
gcc_assert (i != NO_PARTITION);
gcc_assert (tab->num_in_part[i] != 0);
#endif
/* Only dependencies on ssa_names which are coalesced with something need
to be tracked. Partitions with containing only a single SSA_NAME
*cannot* have their value changed. */
if (tab->num_in_part[i] > 1)
{
add_to_partition_kill_list (tab, i, version);
make_dependent_on_partition (tab, version, i);
}
}
}
static void
sese_build_liveouts_use (sese region, bitmap liveouts, basic_block bb,
tree use)
{
unsigned ver;
basic_block def_bb;
if (TREE_CODE (use) != SSA_NAME)
return;
ver = SSA_NAME_VERSION (use);
def_bb = gimple_bb (SSA_NAME_DEF_STMT (use));
if (!def_bb
|| !bb_in_sese_p (def_bb, region)
|| bb_in_sese_p (bb, region))
return;
bitmap_set_bit (liveouts, ver);
}
/* Return SSA names that are unused to GGC memory and compact the SSA
version namespace. This is used to keep footprint of compiler during
interprocedural optimization. */
static unsigned int
release_dead_ssa_names (void)
{
tree t;
unsigned i, j;
int n = VEC_length (tree, FREE_SSANAMES (cfun));
referenced_var_iterator rvi;
/* Current defs point to various dead SSA names that in turn point to
eventually dead variables so a bunch of memory is held live. */
FOR_EACH_REFERENCED_VAR (cfun, t, rvi)
set_current_def (t, NULL);
/* Now release the freelist. */
VEC_free (tree, gc, FREE_SSANAMES (cfun));
FREE_SSANAMES (cfun) = NULL;
/* And compact the SSA number space. We make sure to not change the
relative order of SSA versions. */
for (i = 1, j = 1; i < VEC_length (tree, cfun->gimple_df->ssa_names); ++i)
{
tree name = ssa_name (i);
if (name)
{
if (i != j)
{
SSA_NAME_VERSION (name) = j;
VEC_replace (tree, cfun->gimple_df->ssa_names, j, name);
}
j++;
}
}
VEC_truncate (tree, cfun->gimple_df->ssa_names, j);
statistics_counter_event (cfun, "SSA names released", n);
statistics_counter_event (cfun, "SSA name holes removed", i - j);
if (dump_file)
fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
n, n * 100.0 / num_ssa_names, i - j);
return 0;
}
static complex_lattice_t
find_lattice_value (tree t)
{
tree real, imag;
switch (TREE_CODE (t))
{
case SSA_NAME:
return complex_lattice_values[SSA_NAME_VERSION (t)];
case COMPLEX_CST:
real = TREE_REALPART (t);
imag = TREE_IMAGPART (t);
break;
default:
gcc_unreachable ();
}
return find_lattice_value_parts (real, imag);
}
static complex_lattice_t
find_lattice_value (tree t)
{
tree real, imag;
int r, i;
complex_lattice_t ret;
switch (TREE_CODE (t))
{
case SSA_NAME:
return VEC_index (complex_lattice_t, complex_lattice_values,
SSA_NAME_VERSION (t));
case COMPLEX_CST:
real = TREE_REALPART (t);
imag = TREE_IMAGPART (t);
break;
case COMPLEX_EXPR:
real = TREE_OPERAND (t, 0);
imag = TREE_OPERAND (t, 1);
break;
default:
gcc_unreachable ();
}
r = some_nonzerop (real);
i = some_nonzerop (imag);
ret = r*ONLY_REAL + i*ONLY_IMAG;
/* ??? On occasion we could do better than mapping 0+0i to real, but we
certainly don't want to leave it UNINITIALIZED, which eventually gets
mapped to VARYING. */
if (ret == UNINITIALIZED)
ret = ONLY_REAL;
return ret;
}
void
release_ssa_name (tree var)
{
if (!var)
return;
/* Never release the default definition for a symbol. It's a
special SSA name that should always exist once it's created. */
if (SSA_NAME_IS_DEFAULT_DEF (var))
return;
/* If VAR has been registered for SSA updating, don't remove it.
After update_ssa has run, the name will be released. */
if (name_registered_for_update_p (var))
{
release_ssa_name_after_update_ssa (var);
return;
}
/* release_ssa_name can be called multiple times on a single SSA_NAME.
However, it should only end up on our free list one time. We
keep a status bit in the SSA_NAME node itself to indicate it has
been put on the free list.
Note that once on the freelist you can not reference the SSA_NAME's
defining statement. */
if (! SSA_NAME_IN_FREE_LIST (var))
{
tree saved_ssa_name_var = SSA_NAME_VAR (var);
int saved_ssa_name_version = SSA_NAME_VERSION (var);
use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
if (MAY_HAVE_DEBUG_STMTS)
insert_debug_temp_for_var_def (NULL, var);
#ifdef ENABLE_CHECKING
verify_imm_links (stderr, var);
#endif
while (imm->next != imm)
delink_imm_use (imm->next);
(*SSANAMES (cfun))[SSA_NAME_VERSION (var)] = NULL_TREE;
memset (var, 0, tree_size (var));
imm->prev = imm;
imm->next = imm;
imm->loc.ssa_name = var;
/* First put back the right tree node so that the tree checking
macros do not complain. */
TREE_SET_CODE (var, SSA_NAME);
/* Restore the version number. */
SSA_NAME_VERSION (var) = saved_ssa_name_version;
/* Hopefully this can go away once we have the new incremental
SSA updating code installed. */
SET_SSA_NAME_VAR_OR_IDENTIFIER (var, saved_ssa_name_var);
/* Note this SSA_NAME is now in the first list. */
SSA_NAME_IN_FREE_LIST (var) = 1;
/* And finally put it on the free list. */
vec_safe_push (FREE_SSANAMES (cfun), var);
}
}
