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tree-sra.c
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tree-sra.c
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/* Scalar Replacement of Aggregates (SRA) converts some structure
references into scalar references, exposing them to the scalar
optimizers.
Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
Contributed by Martin Jambor <mjambor@suse.cz>
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/>. */
/* This file implements Scalar Reduction of Aggregates (SRA). SRA is run
twice, once in the early stages of compilation (early SRA) and once in the
late stages (late SRA). The aim of both is to turn references to scalar
parts of aggregates into uses of independent scalar variables.
The two passes are nearly identical, the only difference is that early SRA
does not scalarize unions which are used as the result in a GIMPLE_RETURN
statement because together with inlining this can lead to weird type
conversions.
Both passes operate in four stages:
1. The declarations that have properties which make them candidates for
scalarization are identified in function find_var_candidates(). The
candidates are stored in candidate_bitmap.
2. The function body is scanned. In the process, declarations which are
used in a manner that prevent their scalarization are removed from the
candidate bitmap. More importantly, for every access into an aggregate,
an access structure (struct access) is created by create_access() and
stored in a vector associated with the aggregate. Among other
information, the aggregate declaration, the offset and size of the access
and its type are stored in the structure.
On a related note, assign_link structures are created for every assign
statement between candidate aggregates and attached to the related
accesses.
3. The vectors of accesses are analyzed. They are first sorted according to
their offset and size and then scanned for partially overlapping accesses
(i.e. those which overlap but one is not entirely within another). Such
an access disqualifies the whole aggregate from being scalarized.
If there is no such inhibiting overlap, a representative access structure
is chosen for every unique combination of offset and size. Afterwards,
the pass builds a set of trees from these structures, in which children
of an access are within their parent (in terms of offset and size).
Then accesses are propagated whenever possible (i.e. in cases when it
does not create a partially overlapping access) across assign_links from
the right hand side to the left hand side.
Then the set of trees for each declaration is traversed again and those
accesses which should be replaced by a scalar are identified.
4. The function is traversed again, and for every reference into an
aggregate that has some component which is about to be scalarized,
statements are amended and new statements are created as necessary.
Finally, if a parameter got scalarized, the scalar replacements are
initialized with values from respective parameter aggregates. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "alloc-pool.h"
#include "tm.h"
#include "tree.h"
#include "gimple.h"
#include "cgraph.h"
#include "tree-flow.h"
#include "ipa-prop.h"
#include "tree-pretty-print.h"
#include "statistics.h"
#include "tree-dump.h"
#include "timevar.h"
#include "params.h"
#include "target.h"
#include "flags.h"
#include "dbgcnt.h"
#include "tree-inline.h"
#include "gimple-pretty-print.h"
/* Enumeration of all aggregate reductions we can do. */
enum sra_mode { SRA_MODE_EARLY_IPA, /* early call regularization */
SRA_MODE_EARLY_INTRA, /* early intraprocedural SRA */
SRA_MODE_INTRA }; /* late intraprocedural SRA */
/* Global variable describing which aggregate reduction we are performing at
the moment. */
static enum sra_mode sra_mode;
struct assign_link;
/* ACCESS represents each access to an aggregate variable (as a whole or a
part). It can also represent a group of accesses that refer to exactly the
same fragment of an aggregate (i.e. those that have exactly the same offset
and size). Such representatives for a single aggregate, once determined,
are linked in a linked list and have the group fields set.
Moreover, when doing intraprocedural SRA, a tree is built from those
representatives (by the means of first_child and next_sibling pointers), in
which all items in a subtree are "within" the root, i.e. their offset is
greater or equal to offset of the root and offset+size is smaller or equal
to offset+size of the root. Children of an access are sorted by offset.
Note that accesses to parts of vector and complex number types always
represented by an access to the whole complex number or a vector. It is a
duty of the modifying functions to replace them appropriately. */
struct access
{
/* Values returned by `get_ref_base_and_extent' for each component reference
If EXPR isn't a component reference just set `BASE = EXPR', `OFFSET = 0',
`SIZE = TREE_SIZE (TREE_TYPE (expr))'. */
HOST_WIDE_INT offset;
HOST_WIDE_INT size;
tree base;
/* Expression. It is context dependent so do not use it to create new
expressions to access the original aggregate. See PR 42154 for a
testcase. */
tree expr;
/* Type. */
tree type;
/* The statement this access belongs to. */
gimple stmt;
/* Next group representative for this aggregate. */
struct access *next_grp;
/* Pointer to the group representative. Pointer to itself if the struct is
the representative. */
struct access *group_representative;
/* If this access has any children (in terms of the definition above), this
points to the first one. */
struct access *first_child;
/* In intraprocedural SRA, pointer to the next sibling in the access tree as
described above. In IPA-SRA this is a pointer to the next access
belonging to the same group (having the same representative). */
struct access *next_sibling;
/* Pointers to the first and last element in the linked list of assign
links. */
struct assign_link *first_link, *last_link;
/* Pointer to the next access in the work queue. */
struct access *next_queued;
/* Replacement variable for this access "region." Never to be accessed
directly, always only by the means of get_access_replacement() and only
when grp_to_be_replaced flag is set. */
tree replacement_decl;
/* Is this particular access write access? */
unsigned write : 1;
/* Is this access an artificial one created to scalarize some record
entirely? */
unsigned total_scalarization : 1;
/* Is this access an access to a non-addressable field? */
unsigned non_addressable : 1;
/* Is this access currently in the work queue? */
unsigned grp_queued : 1;
/* Does this group contain a write access? This flag is propagated down the
access tree. */
unsigned grp_write : 1;
/* Does this group contain a read access? This flag is propagated down the
access tree. */
unsigned grp_read : 1;
/* Does this group contain a read access that comes from an assignment
statement? This flag is propagated down the access tree. */
unsigned grp_assignment_read : 1;
/* Does this group contain a write access that comes from an assignment
statement? This flag is propagated down the access tree. */
unsigned grp_assignment_write : 1;
/* Does this group contain a read access through a scalar type? This flag is
not propagated in the access tree in any direction. */
unsigned grp_scalar_read : 1;
/* Does this group contain a write access through a scalar type? This flag
is not propagated in the access tree in any direction. */
unsigned grp_scalar_write : 1;
/* Other passes of the analysis use this bit to make function
analyze_access_subtree create scalar replacements for this group if
possible. */
unsigned grp_hint : 1;
/* Is the subtree rooted in this access fully covered by scalar
replacements? */
unsigned grp_covered : 1;
/* If set to true, this access and all below it in an access tree must not be
scalarized. */
unsigned grp_unscalarizable_region : 1;
/* Whether data have been written to parts of the aggregate covered by this
access which is not to be scalarized. This flag is propagated up in the
access tree. */
unsigned grp_unscalarized_data : 1;
/* Does this access and/or group contain a write access through a
BIT_FIELD_REF? */
unsigned grp_partial_lhs : 1;
/* Set when a scalar replacement should be created for this variable. We do
the decision and creation at different places because create_tmp_var
cannot be called from within FOR_EACH_REFERENCED_VAR. */
unsigned grp_to_be_replaced : 1;
/* Should TREE_NO_WARNING of a replacement be set? */
unsigned grp_no_warning : 1;
/* Is it possible that the group refers to data which might be (directly or
otherwise) modified? */
unsigned grp_maybe_modified : 1;
/* Set when this is a representative of a pointer to scalar (i.e. by
reference) parameter which we consider for turning into a plain scalar
(i.e. a by value parameter). */
unsigned grp_scalar_ptr : 1;
/* Set when we discover that this pointer is not safe to dereference in the
caller. */
unsigned grp_not_necessarilly_dereferenced : 1;
};
typedef struct access *access_p;
DEF_VEC_P (access_p);
DEF_VEC_ALLOC_P (access_p, heap);
/* Alloc pool for allocating access structures. */
static alloc_pool access_pool;
/* A structure linking lhs and rhs accesses from an aggregate assignment. They
are used to propagate subaccesses from rhs to lhs as long as they don't
conflict with what is already there. */
struct assign_link
{
struct access *lacc, *racc;
struct assign_link *next;
};
/* Alloc pool for allocating assign link structures. */
static alloc_pool link_pool;
/* Base (tree) -> Vector (VEC(access_p,heap) *) map. */
static struct pointer_map_t *base_access_vec;
/* Bitmap of candidates. */
static bitmap candidate_bitmap;
/* Bitmap of candidates which we should try to entirely scalarize away and
those which cannot be (because they are and need be used as a whole). */
static bitmap should_scalarize_away_bitmap, cannot_scalarize_away_bitmap;
/* Obstack for creation of fancy names. */
static struct obstack name_obstack;
/* Head of a linked list of accesses that need to have its subaccesses
propagated to their assignment counterparts. */
static struct access *work_queue_head;
/* Number of parameters of the analyzed function when doing early ipa SRA. */
static int func_param_count;
/* scan_function sets the following to true if it encounters a call to
__builtin_apply_args. */
static bool encountered_apply_args;
/* Set by scan_function when it finds a recursive call. */
static bool encountered_recursive_call;
/* Set by scan_function when it finds a recursive call with less actual
arguments than formal parameters.. */
static bool encountered_unchangable_recursive_call;
/* This is a table in which for each basic block and parameter there is a
distance (offset + size) in that parameter which is dereferenced and
accessed in that BB. */
static HOST_WIDE_INT *bb_dereferences;
/* Bitmap of BBs that can cause the function to "stop" progressing by
returning, throwing externally, looping infinitely or calling a function
which might abort etc.. */
static bitmap final_bbs;
/* Representative of no accesses at all. */
static struct access no_accesses_representant;
/* Predicate to test the special value. */
static inline bool
no_accesses_p (struct access *access)
{
return access == &no_accesses_representant;
}
/* Dump contents of ACCESS to file F in a human friendly way. If GRP is true,
representative fields are dumped, otherwise those which only describe the
individual access are. */
static struct
{
/* Number of processed aggregates is readily available in
analyze_all_variable_accesses and so is not stored here. */
/* Number of created scalar replacements. */
int replacements;
/* Number of times sra_modify_expr or sra_modify_assign themselves changed an
expression. */
int exprs;
/* Number of statements created by generate_subtree_copies. */
int subtree_copies;
/* Number of statements created by load_assign_lhs_subreplacements. */
int subreplacements;
/* Number of times sra_modify_assign has deleted a statement. */
int deleted;
/* Number of times sra_modify_assign has to deal with subaccesses of LHS and
RHS reparately due to type conversions or nonexistent matching
references. */
int separate_lhs_rhs_handling;
/* Number of parameters that were removed because they were unused. */
int deleted_unused_parameters;
/* Number of scalars passed as parameters by reference that have been
converted to be passed by value. */
int scalar_by_ref_to_by_val;
/* Number of aggregate parameters that were replaced by one or more of their
components. */
int aggregate_params_reduced;
/* Numbber of components created when splitting aggregate parameters. */
int param_reductions_created;
} sra_stats;
static void
dump_access (FILE *f, struct access *access, bool grp)
{
fprintf (f, "access { ");
fprintf (f, "base = (%d)'", DECL_UID (access->base));
print_generic_expr (f, access->base, 0);
fprintf (f, "', offset = " HOST_WIDE_INT_PRINT_DEC, access->offset);
fprintf (f, ", size = " HOST_WIDE_INT_PRINT_DEC, access->size);
fprintf (f, ", expr = ");
print_generic_expr (f, access->expr, 0);
fprintf (f, ", type = ");
print_generic_expr (f, access->type, 0);
if (grp)
fprintf (f, ", total_scalarization = %d, grp_read = %d, grp_write = %d, "
"grp_assignment_read = %d, grp_assignment_write = %d, "
"grp_scalar_read = %d, grp_scalar_write = %d, "
"grp_hint = %d, grp_covered = %d, "
"grp_unscalarizable_region = %d, grp_unscalarized_data = %d, "
"grp_partial_lhs = %d, grp_to_be_replaced = %d, "
"grp_maybe_modified = %d, "
"grp_not_necessarilly_dereferenced = %d\n",
access->total_scalarization, access->grp_read, access->grp_write,
access->grp_assignment_read, access->grp_assignment_write,
access->grp_scalar_read, access->grp_scalar_write,
access->grp_hint, access->grp_covered,
access->grp_unscalarizable_region, access->grp_unscalarized_data,
access->grp_partial_lhs, access->grp_to_be_replaced,
access->grp_maybe_modified,
access->grp_not_necessarilly_dereferenced);
else
fprintf (f, ", write = %d, total_scalarization = %d, "
"grp_partial_lhs = %d\n",
access->write, access->total_scalarization,
access->grp_partial_lhs);
}
/* Dump a subtree rooted in ACCESS to file F, indent by LEVEL. */
static void
dump_access_tree_1 (FILE *f, struct access *access, int level)
{
do
{
int i;
for (i = 0; i < level; i++)
fputs ("* ", dump_file);
dump_access (f, access, true);
if (access->first_child)
dump_access_tree_1 (f, access->first_child, level + 1);
access = access->next_sibling;
}
while (access);
}
/* Dump all access trees for a variable, given the pointer to the first root in
ACCESS. */
static void
dump_access_tree (FILE *f, struct access *access)
{
for (; access; access = access->next_grp)
dump_access_tree_1 (f, access, 0);
}
/* Return true iff ACC is non-NULL and has subaccesses. */
static inline bool
access_has_children_p (struct access *acc)
{
return acc && acc->first_child;
}
/* Return a vector of pointers to accesses for the variable given in BASE or
NULL if there is none. */
static VEC (access_p, heap) *
get_base_access_vector (tree base)
{
void **slot;
slot = pointer_map_contains (base_access_vec, base);
if (!slot)
return NULL;
else
return *(VEC (access_p, heap) **) slot;
}
/* Find an access with required OFFSET and SIZE in a subtree of accesses rooted
in ACCESS. Return NULL if it cannot be found. */
static struct access *
find_access_in_subtree (struct access *access, HOST_WIDE_INT offset,
HOST_WIDE_INT size)
{
while (access && (access->offset != offset || access->size != size))
{
struct access *child = access->first_child;
while (child && (child->offset + child->size <= offset))
child = child->next_sibling;
access = child;
}
return access;
}
/* Return the first group representative for DECL or NULL if none exists. */
static struct access *
get_first_repr_for_decl (tree base)
{
VEC (access_p, heap) *access_vec;
access_vec = get_base_access_vector (base);
if (!access_vec)
return NULL;
return VEC_index (access_p, access_vec, 0);
}
/* Find an access representative for the variable BASE and given OFFSET and
SIZE. Requires that access trees have already been built. Return NULL if
it cannot be found. */
static struct access *
get_var_base_offset_size_access (tree base, HOST_WIDE_INT offset,
HOST_WIDE_INT size)
{
struct access *access;
access = get_first_repr_for_decl (base);
while (access && (access->offset + access->size <= offset))
access = access->next_grp;
if (!access)
return NULL;
return find_access_in_subtree (access, offset, size);
}
/* Add LINK to the linked list of assign links of RACC. */
static void
add_link_to_rhs (struct access *racc, struct assign_link *link)
{
gcc_assert (link->racc == racc);
if (!racc->first_link)
{
gcc_assert (!racc->last_link);
racc->first_link = link;
}
else
racc->last_link->next = link;
racc->last_link = link;
link->next = NULL;
}
/* Move all link structures in their linked list in OLD_RACC to the linked list
in NEW_RACC. */
static void
relink_to_new_repr (struct access *new_racc, struct access *old_racc)
{
if (!old_racc->first_link)
{
gcc_assert (!old_racc->last_link);
return;
}
if (new_racc->first_link)
{
gcc_assert (!new_racc->last_link->next);
gcc_assert (!old_racc->last_link || !old_racc->last_link->next);
new_racc->last_link->next = old_racc->first_link;
new_racc->last_link = old_racc->last_link;
}
else
{
gcc_assert (!new_racc->last_link);
new_racc->first_link = old_racc->first_link;
new_racc->last_link = old_racc->last_link;
}
old_racc->first_link = old_racc->last_link = NULL;
}
/* Add ACCESS to the work queue (which is actually a stack). */
static void
add_access_to_work_queue (struct access *access)
{
if (!access->grp_queued)
{
gcc_assert (!access->next_queued);
access->next_queued = work_queue_head;
access->grp_queued = 1;
work_queue_head = access;
}
}
/* Pop an access from the work queue, and return it, assuming there is one. */
static struct access *
pop_access_from_work_queue (void)
{
struct access *access = work_queue_head;
work_queue_head = access->next_queued;
access->next_queued = NULL;
access->grp_queued = 0;
return access;
}
/* Allocate necessary structures. */
static void
sra_initialize (void)
{
candidate_bitmap = BITMAP_ALLOC (NULL);
should_scalarize_away_bitmap = BITMAP_ALLOC (NULL);
cannot_scalarize_away_bitmap = BITMAP_ALLOC (NULL);
gcc_obstack_init (&name_obstack);
access_pool = create_alloc_pool ("SRA accesses", sizeof (struct access), 16);
link_pool = create_alloc_pool ("SRA links", sizeof (struct assign_link), 16);
base_access_vec = pointer_map_create ();
memset (&sra_stats, 0, sizeof (sra_stats));
encountered_apply_args = false;
encountered_recursive_call = false;
encountered_unchangable_recursive_call = false;
}
/* Hook fed to pointer_map_traverse, deallocate stored vectors. */
static bool
delete_base_accesses (const void *key ATTRIBUTE_UNUSED, void **value,
void *data ATTRIBUTE_UNUSED)
{
VEC (access_p, heap) *access_vec;
access_vec = (VEC (access_p, heap) *) *value;
VEC_free (access_p, heap, access_vec);
return true;
}
/* Deallocate all general structures. */
static void
sra_deinitialize (void)
{
BITMAP_FREE (candidate_bitmap);
BITMAP_FREE (should_scalarize_away_bitmap);
BITMAP_FREE (cannot_scalarize_away_bitmap);
free_alloc_pool (access_pool);
free_alloc_pool (link_pool);
obstack_free (&name_obstack, NULL);
pointer_map_traverse (base_access_vec, delete_base_accesses, NULL);
pointer_map_destroy (base_access_vec);
}
/* Remove DECL from candidates for SRA and write REASON to the dump file if
there is one. */
static void
disqualify_candidate (tree decl, const char *reason)
{
bitmap_clear_bit (candidate_bitmap, DECL_UID (decl));
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "! Disqualifying ");
print_generic_expr (dump_file, decl, 0);
fprintf (dump_file, " - %s\n", reason);
}
}
/* Return true iff the type contains a field or an element which does not allow
scalarization. */
static bool
type_internals_preclude_sra_p (tree type)
{
tree fld;
tree et;
switch (TREE_CODE (type))
{
case RECORD_TYPE:
case UNION_TYPE:
case QUAL_UNION_TYPE:
for (fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
if (TREE_CODE (fld) == FIELD_DECL)
{
tree ft = TREE_TYPE (fld);
if (TREE_THIS_VOLATILE (fld)
|| !DECL_FIELD_OFFSET (fld) || !DECL_SIZE (fld)
|| !host_integerp (DECL_FIELD_OFFSET (fld), 1)
|| !host_integerp (DECL_SIZE (fld), 1)
|| (AGGREGATE_TYPE_P (ft)
&& int_bit_position (fld) % BITS_PER_UNIT != 0))
return true;
if (AGGREGATE_TYPE_P (ft)
&& type_internals_preclude_sra_p (ft))
return true;
}
return false;
case ARRAY_TYPE:
et = TREE_TYPE (type);
if (AGGREGATE_TYPE_P (et))
return type_internals_preclude_sra_p (et);
else
return false;
default:
return false;
}
}
/* If T is an SSA_NAME, return NULL if it is not a default def or return its
base variable if it is. Return T if it is not an SSA_NAME. */
static tree
get_ssa_base_param (tree t)
{
if (TREE_CODE (t) == SSA_NAME)
{
if (SSA_NAME_IS_DEFAULT_DEF (t))
return SSA_NAME_VAR (t);
else
return NULL_TREE;
}
return t;
}
/* Mark a dereference of BASE of distance DIST in a basic block tht STMT
belongs to, unless the BB has already been marked as a potentially
final. */
static void
mark_parm_dereference (tree base, HOST_WIDE_INT dist, gimple stmt)
{
basic_block bb = gimple_bb (stmt);
int idx, parm_index = 0;
tree parm;
if (bitmap_bit_p (final_bbs, bb->index))
return;
for (parm = DECL_ARGUMENTS (current_function_decl);
parm && parm != base;
parm = DECL_CHAIN (parm))
parm_index++;
gcc_assert (parm_index < func_param_count);
idx = bb->index * func_param_count + parm_index;
if (bb_dereferences[idx] < dist)
bb_dereferences[idx] = dist;
}
/* Allocate an access structure for BASE, OFFSET and SIZE, clear it, fill in
the three fields. Also add it to the vector of accesses corresponding to
the base. Finally, return the new access. */
static struct access *
create_access_1 (tree base, HOST_WIDE_INT offset, HOST_WIDE_INT size)
{
VEC (access_p, heap) *vec;
struct access *access;
void **slot;
access = (struct access *) pool_alloc (access_pool);
memset (access, 0, sizeof (struct access));
access->base = base;
access->offset = offset;
access->size = size;
slot = pointer_map_contains (base_access_vec, base);
if (slot)
vec = (VEC (access_p, heap) *) *slot;
else
vec = VEC_alloc (access_p, heap, 32);
VEC_safe_push (access_p, heap, vec, access);
*((struct VEC (access_p,heap) **)
pointer_map_insert (base_access_vec, base)) = vec;
return access;
}
/* Create and insert access for EXPR. Return created access, or NULL if it is
not possible. */
static struct access *
create_access (tree expr, gimple stmt, bool write)
{
struct access *access;
HOST_WIDE_INT offset, size, max_size;
tree base = expr;
bool ptr, unscalarizable_region = false;
base = get_ref_base_and_extent (expr, &offset, &size, &max_size);
if (sra_mode == SRA_MODE_EARLY_IPA
&& TREE_CODE (base) == MEM_REF)
{
base = get_ssa_base_param (TREE_OPERAND (base, 0));
if (!base)
return NULL;
ptr = true;
}
else
ptr = false;
if (!DECL_P (base) || !bitmap_bit_p (candidate_bitmap, DECL_UID (base)))
return NULL;
if (sra_mode == SRA_MODE_EARLY_IPA)
{
if (size < 0 || size != max_size)
{
disqualify_candidate (base, "Encountered a variable sized access.");
return NULL;
}
if (TREE_CODE (expr) == COMPONENT_REF
&& DECL_BIT_FIELD (TREE_OPERAND (expr, 1)))
{
disqualify_candidate (base, "Encountered a bit-field access.");
return NULL;
}
gcc_checking_assert ((offset % BITS_PER_UNIT) == 0);
if (ptr)
mark_parm_dereference (base, offset + size, stmt);
}
else
{
if (size != max_size)
{
size = max_size;
unscalarizable_region = true;
}
if (size < 0)
{
disqualify_candidate (base, "Encountered an unconstrained access.");
return NULL;
}
}
access = create_access_1 (base, offset, size);
access->expr = expr;
access->type = TREE_TYPE (expr);
access->write = write;
access->grp_unscalarizable_region = unscalarizable_region;
access->stmt = stmt;
if (TREE_CODE (expr) == COMPONENT_REF
&& DECL_NONADDRESSABLE_P (TREE_OPERAND (expr, 1)))
access->non_addressable = 1;
return access;
}
/* Return true iff TYPE is a RECORD_TYPE with fields that are either of gimple
register types or (recursively) records with only these two kinds of fields.
It also returns false if any of these records contains a bit-field. */
static bool
type_consists_of_records_p (tree type)
{
tree fld;
if (TREE_CODE (type) != RECORD_TYPE)
return false;
for (fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
if (TREE_CODE (fld) == FIELD_DECL)
{
tree ft = TREE_TYPE (fld);
if (DECL_BIT_FIELD (fld))
return false;
if (!is_gimple_reg_type (ft)
&& !type_consists_of_records_p (ft))
return false;
}
return true;
}
/* Create total_scalarization accesses for all scalar type fields in DECL that
must be of a RECORD_TYPE conforming to type_consists_of_records_p. BASE
must be the top-most VAR_DECL representing the variable, OFFSET must be the
offset of DECL within BASE. REF must be the memory reference expression for
the given decl. */
static void
completely_scalarize_record (tree base, tree decl, HOST_WIDE_INT offset,
tree ref)
{
tree fld, decl_type = TREE_TYPE (decl);
for (fld = TYPE_FIELDS (decl_type); fld; fld = DECL_CHAIN (fld))
if (TREE_CODE (fld) == FIELD_DECL)
{
HOST_WIDE_INT pos = offset + int_bit_position (fld);
tree ft = TREE_TYPE (fld);
tree nref = build3 (COMPONENT_REF, TREE_TYPE (fld), ref, fld,
NULL_TREE);
if (is_gimple_reg_type (ft))
{
struct access *access;
HOST_WIDE_INT size;
size = tree_low_cst (DECL_SIZE (fld), 1);
access = create_access_1 (base, pos, size);
access->expr = nref;
access->type = ft;
access->total_scalarization = 1;
/* Accesses for intraprocedural SRA can have their stmt NULL. */
}
else
completely_scalarize_record (base, fld, pos, nref);
}
}
/* Search the given tree for a declaration by skipping handled components and
exclude it from the candidates. */
static void
disqualify_base_of_expr (tree t, const char *reason)
{
t = get_base_address (t);
if (sra_mode == SRA_MODE_EARLY_IPA
&& TREE_CODE (t) == MEM_REF)
t = get_ssa_base_param (TREE_OPERAND (t, 0));
if (t && DECL_P (t))
disqualify_candidate (t, reason);
}
/* Scan expression EXPR and create access structures for all accesses to
candidates for scalarization. Return the created access or NULL if none is
created. */
static struct access *
build_access_from_expr_1 (tree expr, gimple stmt, bool write)
{
struct access *ret = NULL;
bool partial_ref;
if (TREE_CODE (expr) == BIT_FIELD_REF
|| TREE_CODE (expr) == IMAGPART_EXPR
|| TREE_CODE (expr) == REALPART_EXPR)
{
expr = TREE_OPERAND (expr, 0);
partial_ref = true;
}
else
partial_ref = false;
/* We need to dive through V_C_Es in order to get the size of its parameter
and not the result type. Ada produces such statements. We are also
capable of handling the topmost V_C_E but not any of those buried in other
handled components. */
if (TREE_CODE (expr) == VIEW_CONVERT_EXPR)
expr = TREE_OPERAND (expr, 0);
if (contains_view_convert_expr_p (expr))
{
disqualify_base_of_expr (expr, "V_C_E under a different handled "
"component.");
return NULL;
}
switch (TREE_CODE (expr))
{
case MEM_REF:
if (TREE_CODE (TREE_OPERAND (expr, 0)) != ADDR_EXPR
&& sra_mode != SRA_MODE_EARLY_IPA)
return NULL;
/* fall through */
case VAR_DECL:
case PARM_DECL:
case RESULT_DECL:
case COMPONENT_REF:
case ARRAY_REF:
case ARRAY_RANGE_REF:
ret = create_access (expr, stmt, write);
break;
default:
break;
}
if (write && partial_ref && ret)
ret->grp_partial_lhs = 1;
return ret;
}
/* Scan expression EXPR and create access structures for all accesses to
candidates for scalarization. Return true if any access has been inserted.
STMT must be the statement from which the expression is taken, WRITE must be
true if the expression is a store and false otherwise. */
static bool
build_access_from_expr (tree expr, gimple stmt, bool write)
{
struct access *access;
access = build_access_from_expr_1 (expr, stmt, write);
if (access)
{
/* This means the aggregate is accesses as a whole in a way other than an
assign statement and thus cannot be removed even if we had a scalar
replacement for everything. */
if (cannot_scalarize_away_bitmap)
bitmap_set_bit (cannot_scalarize_away_bitmap, DECL_UID (access->base));
return true;
}