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/* Scalar Replacement of Aggregates (SRA) converts some structure
references into scalar references, exposing them to the scalar
optimizers.
Copyright (C) 2008-2013 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 "tree-pass.h"
#include "ipa-prop.h"
#include "statistics.h"
#include "params.h"
#include "target.h"
#include "flags.h"
#include "dbgcnt.h"
#include "tree-inline.h"
#include "gimple-pretty-print.h"
#include "ipa-inline.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 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;
/* Is this access an artificial one created to scalarize some record
entirely? */
unsigned grp_total_scalarization : 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. */
unsigned grp_to_be_replaced : 1;
/* Set when we want a replacement for the sole purpose of having it in
generated debug statements. */
unsigned grp_to_be_debug_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;
/* 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> *) map. */
static struct pointer_map_t *base_access_vec;
/* Set of candidates. */
static bitmap candidate_bitmap;
static htab_t candidates;
/* For a candidate UID return the candidates decl. */
static inline tree
candidate (unsigned uid)
{
struct tree_decl_minimal t;
t.uid = uid;
return (tree) htab_find_with_hash (candidates, &t, uid);
}
/* 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, ", grp_read = %d, grp_write = %d, grp_assignment_read = %d, "
"grp_assignment_write = %d, grp_scalar_read = %d, "
"grp_scalar_write = %d, grp_total_scalarization = %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_to_be_debug_replaced = %d, grp_maybe_modified = %d, "
"grp_not_necessarilly_dereferenced = %d\n",
access->grp_read, access->grp_write, access->grp_assignment_read,
access->grp_assignment_write, access->grp_scalar_read,
access->grp_scalar_write, access->grp_total_scalarization,
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_to_be_debug_replaced, access->grp_maybe_modified,
access->grp_not_necessarilly_dereferenced);
else
fprintf (f, ", write = %d, grp_total_scalarization = %d, "
"grp_partial_lhs = %d\n",
access->write, access->grp_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 true iff ACC is (partly) covered by at least one replacement. */
static bool
access_has_replacements_p (struct access *acc)
{
struct access *child;
if (acc->grp_to_be_replaced)
return true;
for (child = acc->first_child; child; child = child->next_sibling)
if (access_has_replacements_p (child))
return true;
return false;
}
/* Return a vector of pointers to accesses for the variable given in BASE or
NULL if there is none. */
static vec<access_p> *
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> **) 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> *access_vec;
access_vec = get_base_access_vector (base);
if (!access_vec)
return NULL;
return (*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);
candidates = htab_create (vec_safe_length (cfun->local_decls) / 2,
uid_decl_map_hash, uid_decl_map_eq, 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> *access_vec = (vec<access_p> *) *value;
vec_free (access_vec);
return true;
}
/* Deallocate all general structures. */
static void
sra_deinitialize (void)
{
BITMAP_FREE (candidate_bitmap);
htab_delete (candidates);
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)
{
if (bitmap_clear_bit (candidate_bitmap, DECL_UID (decl)))
htab_clear_slot (candidates,
htab_find_slot_with_hash (candidates, decl,
DECL_UID (decl), NO_INSERT));
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, const char **msg)
{
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))
{
*msg = "volatile structure field";
return true;
}
if (!DECL_FIELD_OFFSET (fld))
{
*msg = "no structure field offset";
return true;
}
if (!DECL_SIZE (fld))
{
*msg = "zero structure field size";
return true;
}
if (!host_integerp (DECL_FIELD_OFFSET (fld), 1))
{
*msg = "structure field offset not fixed";
return true;
}
if (!host_integerp (DECL_SIZE (fld), 1))
{
*msg = "structure field size not fixed";
return true;
}
if (!host_integerp (bit_position (fld), 0))
{
*msg = "structure field size too big";
return true;
}
if (AGGREGATE_TYPE_P (ft)
&& int_bit_position (fld) % BITS_PER_UNIT != 0)
{
*msg = "structure field is bit field";
return true;
}
if (AGGREGATE_TYPE_P (ft) && type_internals_preclude_sra_p (ft, msg))
return true;
}
return false;
case ARRAY_TYPE:
et = TREE_TYPE (type);
if (TYPE_VOLATILE (et))
{
*msg = "element type is volatile";
return true;
}
if (AGGREGATE_TYPE_P (et) && type_internals_preclude_sra_p (et, msg))
return true;
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> *v;
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)
v = (vec<access_p> *) *slot;
else
vec_alloc (v, 32);
v->safe_push (access);
*((vec<access_p> **)
pointer_map_insert (base_access_vec, base)) = v;
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->grp_total_scalarization = 1;
/* Accesses for intraprocedural SRA can have their stmt NULL. */
}
else
completely_scalarize_record (base, fld, pos, nref);
}
}
/* Create total_scalarization accesses for all scalar type fields in VAR and
for VAR a a whole. VAR must be of a RECORD_TYPE conforming to
type_consists_of_records_p. */
static void
completely_scalarize_var (tree var)
{
HOST_WIDE_INT size = tree_low_cst (DECL_SIZE (var), 1);
struct access *access;
access = create_access_1 (var, 0, size);
access->expr = var;
access->type = TREE_TYPE (var);
access->grp_total_scalarization = 1;
completely_scalarize_record (var, var, 0, var);
}
/* 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;
}
if (TREE_THIS_VOLATILE (expr))
{
disqualify_base_of_expr (expr, "part of a volatile reference.");
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;
}
return false;
}
/* Disqualify LHS and RHS for scalarization if STMT must end its basic block in
modes in which it matters, return true iff they have been disqualified. RHS
may be NULL, in that case ignore it. If we scalarize an aggregate in
intra-SRA we may need to add statements after each statement. This is not
possible if a statement unconditionally has to end the basic block. */
static bool
disqualify_ops_if_throwing_stmt (gimple stmt, tree lhs, tree rhs)
{
if ((sra_mode == SRA_MODE_EARLY_INTRA || sra_mode == SRA_MODE_INTRA)
&& (stmt_can_throw_internal (stmt) || stmt_ends_bb_p (stmt)))
{
disqualify_base_of_expr (lhs, "LHS of a throwing stmt.");
if (rhs)
disqualify_base_of_expr (rhs, "RHS of a throwing stmt.");
return true;
}
return false;
}
/* Scan expressions occurring in STMT, create access structures for all accesses
to candidates for scalarization and remove those candidates which occur in
statements or expressions that prevent them from being split apart. Return
true if any access has been inserted. */
static bool
build_accesses_from_assign (gimple stmt)
{
tree lhs, rhs;
struct access *lacc, *racc;
if (!gimple_assign_single_p (stmt)
/* Scope clobbers don't influence scalarization. */
|| gimple_clobber_p (stmt))
return false;
lhs = gimple_assign_lhs (stmt);
rhs = gimple_assign_rhs1 (stmt);
if (disqualify_ops_if_throwing_stmt (stmt, lhs, rhs))
return false;
racc = build_access_from_expr_1 (rhs, stmt, false);
lacc = build_access_from_expr_1 (lhs, stmt, true);
if (lacc)
lacc->grp_assignment_write = 1;
if (racc)
{
racc->grp_assignment_read = 1;
if (should_scalarize_away_bitmap && !gimple_has_volatile_ops (stmt)
&& !is_gimple_reg_type (racc->type))
bitmap_set_bit (should_scalarize_away_bitmap, DECL_UID (racc->base));
}
if (lacc && racc
&& (sra_mode == SRA_MODE_EARLY_INTRA || sra_mode == SRA_MODE_INTRA)
&& !lacc->grp_unscalarizable_region
&& !racc->grp_unscalarizable_region
&& AGGREGATE_TYPE_P (TREE_TYPE (lhs))
&& lacc->size == racc->size
&& useless_type_conversion_p (lacc->type, racc->type))
{
struct assign_link *link;
link = (struct assign_link *) pool_alloc (link_pool);
memset (link, 0, sizeof (struct assign_link));
link->lacc = lacc;
link->racc = racc;
add_link_to_rhs (racc, link);
}
return lacc || racc;
}
/* Callback of walk_stmt_load_store_addr_ops visit_addr used to determine
GIMPLE_ASM operands with memory constrains which cannot be scalarized. */
static bool
asm_visit_addr (gimple, tree op, tree, void *)
{
op = get_base_address (op);
if (op
&& DECL_P (op))
disqualify_candidate (op, "Non-scalarizable GIMPLE_ASM operand.");
return false;
}
/* Return true iff callsite CALL has at least as many actual arguments as there
are formal parameters of the function currently processed by IPA-SRA. */
static inline bool
callsite_has_enough_arguments_p (gimple call)
{
return gimple_call_num_args (call) >= (unsigned) func_param_count;
}
/* Scan function and look for interesting expressions and create access
structures for them. Return true iff any access is created. */
static bool
scan_function (void)
{
basic_block bb;
bool ret = false;
FOR_EACH_BB (bb)
{
gimple_stmt_iterator gsi;
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple stmt = gsi_stmt (gsi);
tree t;
unsigned i;
if (final_bbs && stmt_can_throw_external (stmt))
bitmap_set_bit (final_bbs, bb->index);
switch (gimple_code (stmt))
{
case GIMPLE_RETURN:
t = gimple_return_retval (stmt);
if (t != NULL_TREE)
ret |= build_access_from_expr (t, stmt, false);
if (final_bbs)
bitmap_set_bit (final_bbs, bb->index);
break;
case GIMPLE_ASSIGN:
ret |= build_accesses_from_assign (stmt);
break;
case GIMPLE_CALL:
for (i = 0; i < gimple_call_num_args (stmt); i++)
ret |= build_access_from_expr (gimple_call_arg (stmt, i),
stmt, false);
if (sra_mode == SRA_MODE_EARLY_IPA)
{
tree dest = gimple_call_fndecl (stmt);
int flags = gimple_call_flags (stmt);
if (dest)
{
if (DECL_BUILT_IN_CLASS (dest) == BUILT_IN_NORMAL
&& DECL_FUNCTION_CODE (dest) == BUILT_IN_APPLY_ARGS)
encountered_apply_args = true;
if (cgraph_get_node (dest)
== cgraph_get_node (current_function_decl))
{
encountered_recursive_call = true;
if (!callsite_has_enough_arguments_p (stmt))
encountered_unchangable_recursive_call = true;
}
}
if (final_bbs
&& (flags & (ECF_CONST | ECF_PURE)) == 0)
bitmap_set_bit (final_bbs, bb->index);
}
t = gimple_call_lhs (stmt);
if (t && !disqualify_ops_if_throwing_stmt (stmt, t, NULL))
ret |= build_access_from_expr (t, stmt, true);
break;
case GIMPLE_ASM:
walk_stmt_load_store_addr_ops (stmt, NULL, NULL, NULL,
asm_visit_addr);
if (final_bbs)
bitmap_set_bit (final_bbs, bb->index);
for (i = 0; i < gimple_asm_ninputs (stmt); i++)
{
t = TREE_VALUE (gimple_asm_input_op (stmt, i));
ret |= build_access_from_expr (t, stmt, false);
}
for (i = 0; i < gimple_asm_noutputs (stmt); i++)
{
t = TREE_VALUE (gimple_asm_output_op (stmt, i));
ret |= build_access_from_expr (t, stmt, true);
}
break;
default:
break;
}
}
}
return ret;
}
/* Helper of QSORT function. There are pointers to accesses in the array. An
access is considered smaller than another if it has smaller offset or if the
offsets are the same but is size is bigger. */
static int
compare_access_positions (const void *a, const void *b)
{
const access_p *fp1 = (const access_p *) a;
const access_p *fp2 = (const access_p *) b;
const access_p f1 = *fp1;
const access_p f2 = *fp2;
if (f1->offset != f2->offset)
return f1->offset < f2->offset ? -1 : 1;
if (f1->size == f2->size)
{
if (f1->type == f2->type)
return 0;
/* Put any non-aggregate type before any aggregate type. */
else if (!is_gimple_reg_type (f1->type)
&& is_gimple_reg_type (f2->type))
return 1;
else if (is_gimple_reg_type (f1->type)
&& !is_gimple_reg_type (f2->type))
return -1;
/* Put any complex or vector type before any other scalar type. */
else if (TREE_CODE (f1->type) != COMPLEX_TYPE
&& TREE_CODE (f1->type) != VECTOR_TYPE
&& (TREE_CODE (f2->type) == COMPLEX_TYPE
|| TREE_CODE (f2->type) == VECTOR_TYPE))
return 1;
else if ((TREE_CODE (f1->type) == COMPLEX_TYPE
|| TREE_CODE (f1->type) == VECTOR_TYPE)
&& TREE_CODE (f2->type) != COMPLEX_TYPE
&& TREE_CODE (f2->type) != VECTOR_TYPE)
return -1;
/* Put the integral type with the bigger precision first. */
else if (INTEGRAL_TYPE_P (f1->type)
&& INTEGRAL_TYPE_P (f2->type))
return TYPE_PRECISION (f2->type) - TYPE_PRECISION (f1->type);
/* Put any integral type with non-full precision last. */
else if (INTEGRAL_TYPE_P (f1->type)
&& (TREE_INT_CST_LOW (TYPE_SIZE (f1->type))
!= TYPE_PRECISION (f1->type)))
return 1;
else if (INTEGRAL_TYPE_P (f2->type)
&& (TREE_INT_CST_LOW (TYPE_SIZE (f2->type))
!= TYPE_PRECISION (f2->type)))
return -1;
/* Stabilize the sort. */
return TYPE_UID (f1->type) - TYPE_UID (f2->type);
}
/* We want the bigger accesses first, thus the opposite operator in the next
line: */
return f1->size > f2->size ? -1 : 1;
}
/* Append a name of the declaration to the name obstack. A helper function for
make_fancy_name. */
static void
make_fancy_decl_name (tree decl)
{
char buffer[32];
tree name = DECL_NAME (decl);
if (name)
obstack_grow (&name_obstack, IDENTIFIER_POINTER (name),
IDENTIFIER_LENGTH (name));
else
{
sprintf (buffer, "D%u", DECL_UID (decl));
obstack_grow (&name_obstack, buffer, strlen (buffer));
}
}
/* Helper for make_fancy_name. */
static void
make_fancy_name_1 (tree expr)
{
char buffer[32];
tree index;
if (DECL_P (expr))
{
make_fancy_decl_name (expr);
return;
}
switch (TREE_CODE (expr))
{
case COMPONENT_REF:
make_fancy_name_1 (TREE_OPERAND (expr, 0));
obstack_1grow (&name_obstack, '$');
make_fancy_decl_name (TREE_OPERAND (expr, 1));
break;
case ARRAY_REF:
make_fancy_name_1 (TREE_OPERAND (expr, 0));
obstack_1grow (&name_obstack, '$');
/* Arrays with only one element may not have a constant as their
index. */
index = TREE_OPERAND (expr, 1);
if (TREE_CODE (index) != INTEGER_CST)
break;
sprintf (buffer, HOST_WIDE_INT_PRINT_DEC, TREE_INT_CST_LOW (index));
obstack_grow (&name_obstack, buffer, strlen (buffer));
break;
case ADDR_EXPR:
make_fancy_name_1 (TREE_OPERAND (expr, 0));
break;
case MEM_REF:
make_fancy_name_1 (TREE_OPERAND (expr, 0));
if (!integer_zerop (TREE_OPERAND (expr, 1)))
{
obstack_1grow (&name_obstack, '$');
sprintf (buffer, HOST_WIDE_INT_PRINT_DEC,
TREE_INT_CST_LOW (TREE_OPERAND (expr, 1)));
obstack_grow (&name_obstack, buffer, strlen (buffer));
}
break;
case BIT_FIELD_REF:
case REALPART_EXPR:
case IMAGPART_EXPR:
gcc_unreachable (); /* we treat these as scalars. */
break;
default:
break;
}
}
/* Create a human readable name for replacement variable of ACCESS. */
static char *
make_fancy_name (tree expr)
{
make_fancy_name_1 (expr);
obstack_1grow (&name_obstack, '\0');
return XOBFINISH (&name_obstack, char *);
}
/* Construct a MEM_REF that would reference a part of aggregate BASE of type
EXP_TYPE at the given OFFSET. If BASE is something for which
get_addr_base_and_unit_offset returns NULL, gsi must be non-NULL and is used
to insert new statements either before or below the current one as specified
by INSERT_AFTER. This function is not capable of handling bitfields.
BASE must be either a declaration or a memory reference that has correct
alignment ifformation embeded in it (e.g. a pre-existing one in SRA). */
tree
build_ref_for_offset (location_t loc, tree base, HOST_WIDE_INT offset,
tree exp_type, gimple_stmt_iterator *gsi,
bool insert_after)
{
tree prev_base = base;
tree off;
tree mem_ref;
HOST_WIDE_INT base_offset;
unsigned HOST_WIDE_INT misalign;
unsigned int align;
gcc_checking_assert (offset % BITS_PER_UNIT == 0);
get_object_alignment_1 (base, &align, &misalign);
base = get_addr_base_and_unit_offset (base, &base_offset);
/* get_addr_base_and_unit_offset returns NULL for references with a variable
offset such as array[var_index]. */
if (!base)
{
gimple stmt;
tree tmp, addr;
gcc_checking_assert (gsi);
tmp = make_ssa_name (build_pointer_type (TREE_TYPE (prev_base)), NULL);
addr = build_fold_addr_expr (unshare_expr (prev_base));
STRIP_USELESS_TYPE_CONVERSION (addr);
stmt = gimple_build_assign (tmp, addr);
gimple_set_location (stmt, loc);
if (insert_after)
gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
else
gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
off = build_int_cst (reference_alias_ptr_type (prev_base),
offset / BITS_PER_UNIT);
base = tmp;
}
else if (TREE_CODE (base) == MEM_REF)
{
off = build_int_cst (TREE_TYPE (TREE_OPERAND (base, 1)),
base_offset + offset / BITS_PER_UNIT);
off = int_const_binop (PLUS_EXPR, TREE_OPERAND (base, 1), off);
base = unshare_expr (TREE_OPERAND (base, 0));
}
else
{
off = build_int_cst (reference_alias_ptr_type (base),
base_offset + offset / BITS_PER_UNIT);
base = build_fold_addr_expr (unshare_expr (base));
}
misalign = (misalign + offset) & (align - 1);
if (misalign != 0)
align = (misalign & -misalign);
if (align < TYPE_ALIGN (exp_type))
exp_type = build_aligned_type (exp_type, align);
mem_ref = fold_build2_loc (loc, MEM_REF, exp_type, base, off);
if (TREE_THIS_VOLATILE (prev_base))
TREE_THIS_VOLATILE (mem_ref) = 1;
if (TREE_SIDE_EFFECTS (prev_base))
TREE_SIDE_EFFECTS (mem_ref) = 1;
return mem_ref;
}
/* Construct a memory reference to a part of an aggregate BASE at the given
OFFSET and of the same type as MODEL. In case this is a reference to a
bit-field, the function will replicate the last component_ref of model's
expr to access it. GSI and INSERT_AFTER have the same meaning as in
build_ref_for_offset. */
static tree
build_ref_for_model (location_t loc, tree base, HOST_WIDE_INT offset,
struct access *model, gimple_stmt_iterator *gsi,
bool insert_after)
{
if (TREE_CODE (model->expr) == COMPONENT_REF
&& DECL_BIT_FIELD (TREE_OPERAND (model->expr, 1)))
{
/* This access represents a bit-field. */
tree t, exp_type, fld = TREE_OPERAND (model->expr, 1);
offset -= int_bit_position (fld);
exp_type = TREE_TYPE (TREE_OPERAND (model->expr, 0));
t = build_ref_for_offset (loc, base, offset, exp_type, gsi, insert_after);
return fold_build3_loc (loc, COMPONENT_REF, TREE_TYPE (fld), t, fld,
NULL_TREE);
}
else
return build_ref_for_offset (loc, base, offset, model->type,
gsi, insert_after);
}
/* Attempt to build a memory reference that we could but into a gimple
debug_bind statement. Similar to build_ref_for_model but punts if it has to
create statements and return s NULL instead. This function also ignores
alignment issues and so its results should never end up in non-debug
statements. */
static tree
build_debug_ref_for_model (location_t loc, tree base, HOST_WIDE_INT offset,
struct access *model)
{
HOST_WIDE_INT base_offset;
tree off;
if (TREE_CODE (model->expr) == COMPONENT_REF
&& DECL_BIT_FIELD (TREE_OPERAND (model->expr, 1)))
return NULL_TREE;
base = get_addr_base_and_unit_offset (base, &base_offset);
if (!base)
return NULL_TREE;
if (TREE_CODE (base) == MEM_REF)
{
off = build_int_cst (TREE_TYPE (TREE_OPERAND (base, 1)),
base_offset + offset / BITS_PER_UNIT);
off = int_const_binop (PLUS_EXPR, TREE_OPERAND (base, 1), off);
base = unshare_expr (TREE_OPERAND (base, 0));
}
else
{
off = build_int_cst (reference_alias_ptr_type (base),
base_offset + offset / BITS_PER_UNIT);
base = build_fold_addr_expr (unshare_expr (base));
}
return fold_build2_loc (loc, MEM_REF, model->type, base, off);
}
/* Construct a memory reference consisting of component_refs and array_refs to
a part of an aggregate *RES (which is of type TYPE). The requested part
should have type EXP_TYPE at be the given OFFSET. This function might not
succeed, it returns true when it does and only then *RES points to something
meaningful. This function should be used only to build expressions that we
might need to present to user (e.g. in warnings). In all other situations,
build_ref_for_model or build_ref_for_offset should be used instead. */
static bool
build_user_friendly_ref_for_offset (tree *res, tree type, HOST_WIDE_INT offset,
tree exp_type)
{
while (1)
{
tree fld;
tree tr_size, index, minidx;
HOST_WIDE_INT el_size;
if (offset == 0 && exp_type
&& types_compatible_p (exp_type, type))
return true;
switch (TREE_CODE (type))
{
case UNION_TYPE:
case QUAL_UNION_TYPE:
case RECORD_TYPE:
for (fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
{
HOST_WIDE_INT pos, size;
tree tr_pos, expr, *expr_ptr;
if (TREE_CODE (fld) != FIELD_DECL)
continue;
tr_pos = bit_position (fld);
if (!tr_pos || !host_integerp (tr_pos, 1))
continue;
pos = TREE_INT_CST_LOW (tr_pos);
gcc_assert (TREE_CODE (type) == RECORD_TYPE || pos == 0);
tr_size = DECL_SIZE (fld);
if (!tr_size || !host_integerp (tr_size, 1))
continue;
size = TREE_INT_CST_LOW (tr_size);
if (size == 0)
{
if (pos != offset)
continue;
}
else if (pos > offset || (pos + size) <= offset)
continue;
expr = build3 (COMPONENT_REF, TREE_TYPE (fld), *res, fld,
NULL_TREE);
expr_ptr = &expr;
if (build_user_friendly_ref_for_offset (expr_ptr, TREE_TYPE (fld),
offset - pos, exp_type))
{
*res = expr;
return true;
}
}
return false;
case ARRAY_TYPE:
tr_size = TYPE_SIZE (TREE_TYPE (type));
if (!tr_size || !host_integerp (tr_size, 1))
return false;
el_size = tree_low_cst (tr_size, 1);
minidx = TYPE_MIN_VALUE (TYPE_DOMAIN (type));
if (TREE_CODE (minidx) != INTEGER_CST || el_size == 0)
return false;
index = build_int_cst (TYPE_DOMAIN (type), offset / el_size);
if (!integer_zerop (minidx))
index = int_const_binop (PLUS_EXPR, index, minidx);
*res = build4 (ARRAY_REF, TREE_TYPE (type), *res, index,
NULL_TREE, NULL_TREE);
offset = offset % el_size;
type = TREE_TYPE (type);
break;
default:
if (offset != 0)
return false;
if (exp_type)
return false;
else
return true;
}
}
}
/* Return true iff TYPE is stdarg va_list type. */
static inline bool
is_va_list_type (tree type)
{
return TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (va_list_type_node);
}
/* Print message to dump file why a variable was rejected. */
static void
reject (tree var, const char *msg)
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Rejected (%d): %s: ", DECL_UID (var), msg);
print_generic_expr (dump_file, var, 0);
fprintf (dump_file, "\n");
}
}
/* Return true if VAR is a candidate for SRA. */
static bool
maybe_add_sra_candidate (tree var)
{
tree type = TREE_TYPE (var);
const char *msg;
void **slot;
if (!AGGREGATE_TYPE_P (type))
{
reject (var, "not aggregate");
return false;
}
if (needs_to_live_in_memory (var))
{
reject (var, "needs to live in memory");
return false;
}
if (TREE_THIS_VOLATILE (var))
{
reject (var, "is volatile");
return false;
}
if (!COMPLETE_TYPE_P (type))
{
reject (var, "has incomplete type");
return false;
}
if (!host_integerp (TYPE_SIZE (type), 1))
{
reject (var, "type size not fixed");
return false;
}
if (tree_low_cst (TYPE_SIZE (type), 1) == 0)
{
reject (var, "type size is zero");
return false;
}
if (type_internals_preclude_sra_p (type, &msg))
{
reject (var, msg);
return false;
}
if (/* Fix for PR 41089. tree-stdarg.c needs to have va_lists intact but
we also want to schedule it rather late. Thus we ignore it in
the early pass. */
(sra_mode == SRA_MODE_EARLY_INTRA
&& is_va_list_type (type)))
{
reject (var, "is va_list");
return false;
}
bitmap_set_bit (candidate_bitmap, DECL_UID (var));
slot = htab_find_slot_with_hash (candidates, var, DECL_UID (var), INSERT);
*slot = (void *) var;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Candidate (%d): ", DECL_UID (var));
print_generic_expr (dump_file, var, 0);
fprintf (dump_file, "\n");
}
return true;
}
/* The very first phase of intraprocedural SRA. It marks in candidate_bitmap
those with type which is suitable for scalarization. */
static bool
find_var_candidates (void)
{
tree var, parm;
unsigned int i;
bool ret = false;
for (parm = DECL_ARGUMENTS (current_function_decl);
parm;
parm = DECL_CHAIN (parm))
ret |= maybe_add_sra_candidate (parm);
FOR_EACH_LOCAL_DECL (cfun, i, var)
{
if (TREE_CODE (var) != VAR_DECL)
continue;
ret |= maybe_add_sra_candidate (var);
}
return ret;
}
/* Sort all accesses for the given variable, check for partial overlaps and
return NULL if there are any. If there are none, pick a representative for
each combination of offset and size and create a linked list out of them.
Return the pointer to the first representative and make sure it is the first
one in the vector of accesses. */
static struct access *
sort_and_splice_var_accesses (tree var)
{
int i, j, access_count;
struct access *res, **prev_acc_ptr = &res;
vec<access_p> *access_vec;
bool first = true;
HOST_WIDE_INT low = -1, high = 0;
access_vec = get_base_access_vector (var);
if (!access_vec)
return NULL;
access_count = access_vec->length ();
/* Sort by <OFFSET, SIZE>. */
access_vec->qsort (compare_access_positions);
i = 0;
while (i < access_count)
{
struct access *access = (*access_vec)[i];
bool grp_write = access->write;
bool grp_read = !access->write;
bool grp_scalar_write = access->write
&& is_gimple_reg_type (access->type);
bool grp_scalar_read = !access->write
&& is_gimple_reg_type (access->type);
bool grp_assignment_read = access->grp_assignment_read;
bool grp_assignment_write = access->grp_assignment_write;
bool multiple_scalar_reads = false;
bool total_scalarization = access->grp_total_scalarization;
bool grp_partial_lhs = access->grp_partial_lhs;
bool first_scalar = is_gimple_reg_type (access->type);
bool unscalarizable_region = access->grp_unscalarizable_region;
if (first || access->offset >= high)
{
first = false;
low = access->offset;
high = access->offset + access->size;
}
else if (access->offset > low && access->offset + access->size > high)
return NULL;
else
gcc_assert (access->offset >= low
&& access->offset + access->size <= high);
j = i + 1;
while (j < access_count)
{
struct access *ac2 = (*access_vec)[j];
if (ac2->offset != access->offset || ac2->size != access->size)
break;
if (ac2->write)
{
grp_write = true;
grp_scalar_write = (grp_scalar_write
|| is_gimple_reg_type (ac2->type));
}
else
{
grp_read = true;
if (is_gimple_reg_type (ac2->type))
{
if (grp_scalar_read)
multiple_scalar_reads = true;
else
grp_scalar_read = true;
}
}
grp_assignment_read |= ac2->grp_assignment_read;
grp_assignment_write |= ac2->grp_assignment_write;
grp_partial_lhs |= ac2->grp_partial_lhs;
unscalarizable_region |= ac2->grp_unscalarizable_region;
total_scalarization |= ac2->grp_total_scalarization;
relink_to_new_repr (access, ac2);
/* If there are both aggregate-type and scalar-type accesses with
this combination of size and offset, the comparison function
should have put the scalars first. */
gcc_assert (first_scalar || !is_gimple_reg_type (ac2->type));
ac2->group_representative = access;
j++;
}
i = j;
access->group_representative = access;
access->grp_write = grp_write;
access->grp_read = grp_read;
access->grp_scalar_read = grp_scalar_read;
access->grp_scalar_write = grp_scalar_write;
access->grp_assignment_read = grp_assignment_read;
access->grp_assignment_write = grp_assignment_write;
access->grp_hint = multiple_scalar_reads || total_scalarization;
access->grp_total_scalarization = total_scalarization;
access->grp_partial_lhs = grp_partial_lhs;
access->grp_unscalarizable_region = unscalarizable_region;
if (access->first_link)
add_access_to_work_queue (access);
*prev_acc_ptr = access;
prev_acc_ptr = &access->next_grp;
}
gcc_assert (res == (*access_vec)[0]);
return res;
}
/* Create a variable for the given ACCESS which determines the type, name and a
few other properties. Return the variable declaration and store it also to
ACCESS->replacement. */
static tree
create_access_replacement (struct access *access)
{
tree repl;
if (access->grp_to_be_debug_replaced)
{
repl = create_tmp_var_raw (access->type, NULL);
DECL_CONTEXT (repl) = current_function_decl;
}
else
repl = create_tmp_var (access->type, "SR");
if (TREE_CODE (access->type) == COMPLEX_TYPE
|| TREE_CODE (access->type) == VECTOR_TYPE)
{
if (!access->grp_partial_lhs)
DECL_GIMPLE_REG_P (repl) = 1;
}
else if (access->grp_partial_lhs
&& is_gimple_reg_type (access->type))
TREE_ADDRESSABLE (repl) = 1;
DECL_SOURCE_LOCATION (repl) = DECL_SOURCE_LOCATION (access->base);
DECL_ARTIFICIAL (repl) = 1;
DECL_IGNORED_P (repl) = DECL_IGNORED_P (access->base);
if (DECL_NAME (access->base)
&& !DECL_IGNORED_P (access->base)
&& !DECL_ARTIFICIAL (access->base))
{
char *pretty_name = make_fancy_name (access->expr);
tree debug_expr = unshare_expr_without_location (access->expr), d;
bool fail = false;
DECL_NAME (repl) = get_identifier (pretty_name);
obstack_free (&name_obstack, pretty_name);
/* Get rid of any SSA_NAMEs embedded in debug_expr,
as DECL_DEBUG_EXPR isn't considered when looking for still
used SSA_NAMEs and thus they could be freed. All debug info
generation cares is whether something is constant or variable
and that get_ref_base_and_extent works properly on the
expression. It cannot handle accesses at a non-constant offset
though, so just give up in those cases. */
for (d = debug_expr;
!fail && (handled_component_p (d) || TREE_CODE (d) == MEM_REF);
d = TREE_OPERAND (d, 0))
switch (TREE_CODE (d))
{
case ARRAY_REF:
case ARRAY_RANGE_REF:
if (TREE_OPERAND (d, 1)
&& TREE_CODE (TREE_OPERAND (d, 1)) != INTEGER_CST)
fail = true;
if (TREE_OPERAND (d, 3)
&& TREE_CODE (TREE_OPERAND (d, 3)) != INTEGER_CST)
fail = true;
/* FALLTHRU */
case COMPONENT_REF:
if (TREE_OPERAND (d, 2)
&& TREE_CODE (TREE_OPERAND (d, 2)) != INTEGER_CST)
fail = true;
break;
case MEM_REF:
if (TREE_CODE (TREE_OPERAND (d, 0)) != ADDR_EXPR)
fail = true;
else
d = TREE_OPERAND (d, 0);
break;
default:
break;
}
if (!fail)
{
SET_DECL_DEBUG_EXPR (repl, debug_expr);
DECL_DEBUG_EXPR_IS_FROM (repl) = 1;
}
if (access->grp_no_warning)
TREE_NO_WARNING (repl) = 1;
else
TREE_NO_WARNING (repl) = TREE_NO_WARNING (access->base);
}
else
TREE_NO_WARNING (repl) = 1;
if (dump_file)
{
if (access->grp_to_be_debug_replaced)
{
fprintf (dump_file, "Created a debug-only replacement for ");
print_generic_expr (dump_file, access->base, 0);
fprintf (dump_file, " offset: %u, size: %u\n",
(unsigned) access->offset, (unsigned) access->size);
}
else
{
fprintf (dump_file, "Created a replacement for ");
print_generic_expr (dump_file, access->base, 0);
fprintf (dump_file, " offset: %u, size: %u: ",
(unsigned) access->offset, (unsigned) access->size);
print_generic_expr (dump_file, repl, 0);
fprintf (dump_file, "\n");
}
}
sra_stats.replacements++;
return repl;
}
/* Return ACCESS scalar replacement, create it if it does not exist yet. */
static inline tree
get_access_replacement (struct access *access)
{
gcc_checking_assert (access->replacement_decl);
return access->replacement_decl;
}
/* Build a subtree of accesses rooted in *ACCESS, and move the pointer in the
linked list along the way. Stop when *ACCESS is NULL or the access pointed
to it is not "within" the root. Return false iff some accesses partially
overlap. */
static bool
build_access_subtree (struct access **access)
{
struct access *root = *access, *last_child = NULL;
HOST_WIDE_INT limit = root->offset + root->size;
*access = (*access)->next_grp;
while (*access && (*access)->offset + (*access)->size <= limit)
{
if (!last_child)
root->first_child = *access;
else
last_child->next_sibling = *access;
last_child = *access;
if (!build_access_subtree (access))
return false;
}
if (*access && (*access)->offset < limit)
return false;
return true;
}
/* Build a tree of access representatives, ACCESS is the pointer to the first
one, others are linked in a list by the next_grp field. Return false iff
some accesses partially overlap. */
static bool
build_access_trees (struct access *access)
{
while (access)
{
struct access *root = access;
if (!build_access_subtree (&access))
return false;
root->next_grp = access;
}
return true;
}
/* Return true if expr contains some ARRAY_REFs into a variable bounded
array. */
static bool
expr_with_var_bounded_array_refs_p (tree expr)
{
while (handled_component_p (expr))
{
if (TREE_CODE (expr) == ARRAY_REF
&& !host_integerp (array_ref_low_bound (expr), 0))
return true;
expr = TREE_OPERAND (expr, 0);
}
return false;
}
/* Analyze the subtree of accesses rooted in ROOT, scheduling replacements when
both seeming beneficial and when ALLOW_REPLACEMENTS allows it. Also set all
sorts of access flags appropriately along the way, notably always set
grp_read and grp_assign_read according to MARK_READ and grp_write when
MARK_WRITE is true.
Creating a replacement for a scalar access is considered beneficial if its
grp_hint is set (this means we are either attempting total scalarization or
there is more than one direct read access) or according to the following
table:
Access written to through a scalar type (once or more times)
|
| Written to in an assignment statement
| |
| | Access read as scalar _once_
| | |
| | | Read in an assignment statement
| | | |
| | | | Scalarize Comment
-----------------------------------------------------------------------------
0 0 0 0 No access for the scalar
0 0 0 1 No access for the scalar
0 0 1 0 No Single read - won't help
0 0 1 1 No The same case
0 1 0 0 No access for the scalar
0 1 0 1 No access for the scalar
0 1 1 0 Yes s = *g; return s.i;
0 1 1 1 Yes The same case as above
1 0 0 0 No Won't help
1 0 0 1 Yes s.i = 1; *g = s;
1 0 1 0 Yes s.i = 5; g = s.i;
1 0 1 1 Yes The same case as above
1 1 0 0 No Won't help.
1 1 0 1 Yes s.i = 1; *g = s;
1 1 1 0 Yes s = *g; return s.i;
1 1 1 1 Yes Any of the above yeses */
static bool
analyze_access_subtree (struct access *root, struct access *parent,
bool allow_replacements)
{
struct access *child;
HOST_WIDE_INT limit = root->offset + root->size;
HOST_WIDE_INT covered_to = root->offset;
bool scalar = is_gimple_reg_type (root->type);
bool hole = false, sth_created = false;
if (parent)
{
if (parent->grp_read)
root->grp_read = 1;
if (parent->grp_assignment_read)
root->grp_assignment_read = 1;
if (parent->grp_write)
root->grp_write = 1;
if (parent->grp_assignment_write)
root->grp_assignment_write = 1;
if (parent->grp_total_scalarization)
root->grp_total_scalarization = 1;
}
if (root->grp_unscalarizable_region)
allow_replacements = false;
if (allow_replacements && expr_with_var_bounded_array_refs_p (root->expr))
allow_replacements = false;
for (child = root->first_child; child; child = child->next_sibling)
{
hole |= covered_to < child->offset;
sth_created |= analyze_access_subtree (child, root,
allow_replacements && !scalar);
root->grp_unscalarized_data |= child->grp_unscalarized_data;
root->grp_total_scalarization &= child->grp_total_scalarization;
if (child->grp_covered)
covered_to += child->size;
else
hole = true;
}
if (allow_replacements && scalar && !root->first_child
&& (root->grp_hint
|| ((root->grp_scalar_read || root->grp_assignment_read)
&& (root->grp_scalar_write || root->grp_assignment_write))))
{
/* Always create access replacements that cover the whole access.
For integral types this means the precision has to match.
Avoid assumptions based on the integral type kind, too. */
if (INTEGRAL_TYPE_P (root->type)
&& (TREE_CODE (root->type) != INTEGER_TYPE
|| TYPE_PRECISION (root->type) != root->size)
/* But leave bitfield accesses alone. */
&& (TREE_CODE (root->expr) != COMPONENT_REF
|| !DECL_BIT_FIELD (TREE_OPERAND (root->expr, 1))))
{
tree rt = root->type;
gcc_assert ((root->offset % BITS_PER_UNIT) == 0
&& (root->size % BITS_PER_UNIT) == 0);
root->type = build_nonstandard_integer_type (root->size,
TYPE_UNSIGNED (rt));
root->expr = build_ref_for_offset (UNKNOWN_LOCATION,
root->base, root->offset,
root->type, NULL, false);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Changing the type of a replacement for ");
print_generic_expr (dump_file, root->base, 0);
fprintf (dump_file, " offset: %u, size: %u ",
(unsigned) root->offset, (unsigned) root->size);
fprintf (dump_file, " to an integer.\n");
}
}
root->grp_to_be_replaced = 1;
root->replacement_decl = create_access_replacement (root);
sth_created = true;
hole = false;
}
else
{
if (allow_replacements
&& scalar && !root->first_child
&& (root->grp_scalar_write || root->grp_assignment_write)
&& !bitmap_bit_p (cannot_scalarize_away_bitmap,
DECL_UID (root->base)))
{
gcc_checking_assert (!root->grp_scalar_read
&& !root->grp_assignment_read);
sth_created = true;
if (MAY_HAVE_DEBUG_STMTS)
{
root->grp_to_be_debug_replaced = 1;
root->replacement_decl = create_access_replacement (root);
}
}
if (covered_to < limit)
hole = true;
if (scalar)
root->grp_total_scalarization = 0;
}
if (!hole || root->grp_total_scalarization)
root->grp_covered = 1;
else if (root->grp_write || TREE_CODE (root->base) == PARM_DECL)
root->grp_unscalarized_data = 1; /* not covered and written to */
return sth_created;
}
/* Analyze all access trees linked by next_grp by the means of
analyze_access_subtree. */
static bool
analyze_access_trees (struct access *access)
{
bool ret = false;
while (access)
{
if (analyze_access_subtree (access, NULL, true))
ret = true;
access = access->next_grp;
}
return ret;
}
/* Return true iff a potential new child of LACC at offset OFFSET and with size
SIZE would conflict with an already existing one. If exactly such a child
already exists in LACC, store a pointer to it in EXACT_MATCH. */
static bool
child_would_conflict_in_lacc (struct access *lacc, HOST_WIDE_INT norm_offset,
HOST_WIDE_INT size, struct access **exact_match)
{
struct access *child;
for (child = lacc->first_child; child; child = child->next_sibling)
{
if (child->offset == norm_offset && child->size == size)
{
*exact_match = child;
return true;
}
if (child->offset < norm_offset + size
&& child->offset + child->size > norm_offset)
return true;
}
return false;
}
/* Create a new child access of PARENT, with all properties just like MODEL
except for its offset and with its grp_write false and grp_read true.
Return the new access or NULL if it cannot be created. Note that this access
is created long after all splicing and sorting, it's not located in any
access vector and is automatically a representative of its group. */
static struct access *
create_artificial_child_access (struct access *parent, struct access *model,
HOST_WIDE_INT new_offset)
{
struct access *access;
struct access **child;
tree expr = parent->base;
gcc_assert (!model->grp_unscalarizable_region);
access = (struct access *) pool_alloc (access_pool);
memset (access, 0, sizeof (struct access));
if (!build_user_friendly_ref_for_offset (&expr, TREE_TYPE (expr), new_offset,
model->type))
{
access->grp_no_warning = true;
expr = build_ref_for_model (EXPR_LOCATION (parent->base), parent->base,
new_offset, model, NULL, false);
}
access->base = parent->base;
access->expr = expr;
access->offset = new_offset;
access->size = model->size;
access->type = model->type;
access->grp_write = true;
access->grp_read = false;
child = &parent->first_child;
while (*child && (*child)->offset < new_offset)
child = &(*child)->next_sibling;
access->next_sibling = *child;
*child = access;
return access;
}
/* Propagate all subaccesses of RACC across an assignment link to LACC. Return
true if any new subaccess was created. Additionally, if RACC is a scalar
access but LACC is not, change the type of the latter, if possible. */
static bool
propagate_subaccesses_across_link (struct access *lacc, struct access *racc)
{
struct access *rchild;
HOST_WIDE_INT norm_delta = lacc->offset - racc->offset;
bool ret = false;
if (is_gimple_reg_type (lacc->type)
|| lacc->grp_unscalarizable_region
|| racc->grp_unscalarizable_region)
return false;
if (is_gimple_reg_type (racc->type))
{
if (!lacc->first_child && !racc->first_child)
{
tree t = lacc->base;
lacc->type = racc->type;
if (build_user_friendly_ref_for_offset (&t, TREE_TYPE (t),
lacc->offset, racc->type))
lacc->expr = t;
else
{
lacc->expr = build_ref_for_model (EXPR_LOCATION (lacc->base),
lacc->base, lacc->offset,
racc, NULL, false);
lacc->grp_no_warning = true;
}
}
return false;
}
for (rchild = racc->first_child; rchild; rchild = rchild->next_sibling)
{
struct access *new_acc = NULL;
HOST_WIDE_INT norm_offset = rchild->offset + norm_delta;
if (rchild->grp_unscalarizable_region)
continue;
if (child_would_conflict_in_lacc (lacc, norm_offset, rchild->size,
&new_acc))
{
if (new_acc)
{
rchild->grp_hint = 1;
new_acc->grp_hint |= new_acc->grp_read;
if (rchild->first_child)
ret |= propagate_subaccesses_across_link (new_acc, rchild);
}
continue;
}
rchild->grp_hint = 1;
new_acc = create_artificial_child_access (lacc, rchild, norm_offset);
if (new_acc)
{
ret = true;
if (racc->first_child)
propagate_subaccesses_across_link (new_acc, rchild);
}
}
return ret;
}
/* Propagate all subaccesses across assignment links. */
static void
propagate_all_subaccesses (void)
{
while (work_queue_head)
{
struct access *racc = pop_access_from_work_queue ();
struct assign_link *link;
gcc_assert (racc->first_link);
for (link = racc->first_link; link; link = link->next)
{
struct access *lacc = link->lacc;
if (!bitmap_bit_p (candidate_bitmap, DECL_UID (lacc->base)))
continue;
lacc = lacc->group_representative;
if (propagate_subaccesses_across_link (lacc, racc)
&& lacc->first_link)
add_access_to_work_queue (lacc);
}
}
}
/* Go through all accesses collected throughout the (intraprocedural) analysis
stage, exclude overlapping ones, identify representatives and build trees
out of them, making decisions about scalarization on the way. Return true
iff there are any to-be-scalarized variables after this stage. */
static bool
analyze_all_variable_accesses (void)
{
int res = 0;
bitmap tmp = BITMAP_ALLOC (NULL);
bitmap_iterator bi;
unsigned i, max_total_scalarization_size;
max_total_scalarization_size = UNITS_PER_WORD * BITS_PER_UNIT
* MOVE_RATIO (optimize_function_for_speed_p (cfun));
EXECUTE_IF_SET_IN_BITMAP (candidate_bitmap, 0, i, bi)
if (bitmap_bit_p (should_scalarize_away_bitmap, i)
&& !bitmap_bit_p (cannot_scalarize_away_bitmap, i))
{
tree var = candidate (i);
if (TREE_CODE (var) == VAR_DECL
&& type_consists_of_records_p (TREE_TYPE (var)))
{
if ((unsigned) tree_low_cst (TYPE_SIZE (TREE_TYPE (var)), 1)
<= max_total_scalarization_size)
{
completely_scalarize_var (var);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Will attempt to totally scalarize ");
print_generic_expr (dump_file, var, 0);
fprintf (dump_file, " (UID: %u): \n", DECL_UID (var));
}
}
else if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Too big to totally scalarize: ");
print_generic_expr (dump_file, var, 0);
fprintf (dump_file, " (UID: %u)\n", DECL_UID (var));
}
}
}
bitmap_copy (tmp, candidate_bitmap);
EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi)
{
tree var = candidate (i);
struct access *access;
access = sort_and_splice_var_accesses (var);
if (!access || !build_access_trees (access))
disqualify_candidate (var,
"No or inhibitingly overlapping accesses.");
}
propagate_all_subaccesses ();
bitmap_copy (tmp, candidate_bitmap);
EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi)
{
tree var = candidate (i);
struct access *access = get_first_repr_for_decl (var);
if (analyze_access_trees (access))
{
res++;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nAccess trees for ");
print_generic_expr (dump_file, var, 0);
fprintf (dump_file, " (UID: %u): \n", DECL_UID (var));
dump_access_tree (dump_file, access);
fprintf (dump_file, "\n");
}
}
else
disqualify_candidate (var, "No scalar replacements to be created.");
}
BITMAP_FREE (tmp);
if (res)
{
statistics_counter_event (cfun, "Scalarized aggregates", res);
return true;
}
else
return false;
}
/* Generate statements copying scalar replacements of accesses within a subtree
into or out of AGG. ACCESS, all its children, siblings and their children
are to be processed. AGG is an aggregate type expression (can be a
declaration but does not have to be, it can for example also be a mem_ref or
a series of handled components). TOP_OFFSET is the offset of the processed
subtree which has to be subtracted from offsets of individual accesses to
get corresponding offsets for AGG. If CHUNK_SIZE is non-null, copy only
replacements in the interval <start_offset, start_offset + chunk_size>,
otherwise copy all. GSI is a statement iterator used to place the new
statements. WRITE should be true when the statements should write from AGG
to the replacement and false if vice versa. if INSERT_AFTER is true, new
statements will be added after the current statement in GSI, they will be
added before the statement otherwise. */
static void
generate_subtree_copies (struct access *access, tree agg,
HOST_WIDE_INT top_offset,
HOST_WIDE_INT start_offset, HOST_WIDE_INT chunk_size,
gimple_stmt_iterator *gsi, bool write,
bool insert_after, location_t loc)
{
do
{
if (chunk_size && access->offset >= start_offset + chunk_size)
return;
if (access->grp_to_be_replaced
&& (chunk_size == 0
|| access->offset + access->size > start_offset))
{
tree expr, repl = get_access_replacement (access);
gimple stmt;
expr = build_ref_for_model (loc, agg, access->offset - top_offset,
access, gsi, insert_after);
if (write)
{
if (access->grp_partial_lhs)
expr = force_gimple_operand_gsi (gsi, expr, true, NULL_TREE,
!insert_after,
insert_after ? GSI_NEW_STMT
: GSI_SAME_STMT);
stmt = gimple_build_assign (repl, expr);
}
else
{
TREE_NO_WARNING (repl) = 1;
if (access->grp_partial_lhs)
repl = force_gimple_operand_gsi (gsi, repl, true, NULL_TREE,
!insert_after,
insert_after ? GSI_NEW_STMT
: GSI_SAME_STMT);
stmt = gimple_build_assign (expr, repl);
}
gimple_set_location (stmt, loc);
if (insert_after)
gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
else
gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
update_stmt (stmt);
sra_stats.subtree_copies++;
}
else if (write
&& access->grp_to_be_debug_replaced
&& (chunk_size == 0
|| access->offset + access->size > start_offset))
{
gimple ds;
tree drhs = build_debug_ref_for_model (loc, agg,
access->offset - top_offset,
access);
ds = gimple_build_debug_bind (get_access_replacement (access),
drhs, gsi_stmt (*gsi));
if (insert_after)
gsi_insert_after (gsi, ds, GSI_NEW_STMT);
else
gsi_insert_before (gsi, ds, GSI_SAME_STMT);
}
if (access->first_child)
generate_subtree_copies (access->first_child, agg, top_offset,
start_offset, chunk_size, gsi,
write, insert_after, loc);
access = access->next_sibling;
}
while (access);
}
/* Assign zero to all scalar replacements in an access subtree. ACCESS is the
the root of the subtree to be processed. GSI is the statement iterator used
for inserting statements which are added after the current statement if
INSERT_AFTER is true or before it otherwise. */
static void
init_subtree_with_zero (struct access *access, gimple_stmt_iterator *gsi,
bool insert_after, location_t loc)
{
struct access *child;
if (access->grp_to_be_replaced)
{
gimple stmt;
stmt = gimple_build_assign (get_access_replacement (access),
build_zero_cst (access->type));
if (insert_after)
gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
else
gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
update_stmt (stmt);
gimple_set_location (stmt, loc);
}
else if (access->grp_to_be_debug_replaced)
{
gimple ds = gimple_build_debug_bind (get_access_replacement (access),
build_zero_cst (access->type),
gsi_stmt (*gsi));
if (insert_after)
gsi_insert_after (gsi, ds, GSI_NEW_STMT);
else
gsi_insert_before (gsi, ds, GSI_SAME_STMT);
}
for (child = access->first_child; child; child = child->next_sibling)
init_subtree_with_zero (child, gsi, insert_after, loc);
}
/* Search for an access representative for the given expression EXPR and
return it or NULL if it cannot be found. */
static struct access *
get_access_for_expr (tree expr)
{
HOST_WIDE_INT offset, size, max_size;
tree base;
/* FIXME: This should not be necessary but Ada produces V_C_Es with a type of
a different size than the size of its argument and we need the latter
one. */
if (TREE_CODE (expr) == VIEW_CONVERT_EXPR)
expr = TREE_OPERAND (expr, 0);
base = get_ref_base_and_extent (expr, &offset, &size, &max_size);
if (max_size == -1 || !DECL_P (base))
return NULL;
if (!bitmap_bit_p (candidate_bitmap, DECL_UID (base)))
return NULL;
return get_var_base_offset_size_access (base, offset, max_size);
}
/* Replace the expression EXPR with a scalar replacement if there is one and
generate other statements to do type conversion or subtree copying if
necessary. GSI is used to place newly created statements, WRITE is true if
the expression is being written to (it is on a LHS of a statement or output
in an assembly statement). */
static bool
sra_modify_expr (tree *expr, gimple_stmt_iterator *gsi, bool write)
{
location_t loc;
struct access *access;
tree type, bfr;
if (TREE_CODE (*expr) == BIT_FIELD_REF)
{
bfr = *expr;
expr = &TREE_OPERAND (*expr, 0);
}
else
bfr = NULL_TREE;
if (TREE_CODE (*expr) == REALPART_EXPR || TREE_CODE (*expr) == IMAGPART_EXPR)
expr = &TREE_OPERAND (*expr, 0);
access = get_access_for_expr (*expr);
if (!access)
return false;
type = TREE_TYPE (*expr);
loc = gimple_location (gsi_stmt (*gsi));
if (access->grp_to_be_replaced)
{
tree repl = get_access_replacement (access);
/* If we replace a non-register typed access simply use the original
access expression to extract the scalar component afterwards.
This happens if scalarizing a function return value or parameter
like in gcc.c-torture/execute/20041124-1.c, 20050316-1.c and
gcc.c-torture/compile/20011217-1.c.
We also want to use this when accessing a complex or vector which can
be accessed as a different type too, potentially creating a need for
type conversion (see PR42196) and when scalarized unions are involved
in assembler statements (see PR42398). */
if (!useless_type_conversion_p (type, access->type))
{
tree ref;
ref = build_ref_for_model (loc, access->base, access->offset, access,
NULL, false);
if (write)
{
gimple stmt;
if (access->grp_partial_lhs)
ref = force_gimple_operand_gsi (gsi, ref, true, NULL_TREE,
false, GSI_NEW_STMT);
stmt = gimple_build_assign (repl, ref);
gimple_set_location (stmt, loc);
gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
}
else
{
gimple stmt;
if (access->grp_partial_lhs)
repl = force_gimple_operand_gsi (gsi, repl, true, NULL_TREE,
true, GSI_SAME_STMT);
stmt = gimple_build_assign (ref, repl);
gimple_set_location (stmt, loc);
gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
}
}
else
*expr = repl;
sra_stats.exprs++;
}
else if (write && access->grp_to_be_debug_replaced)
{
gimple ds = gimple_build_debug_bind (get_access_replacement (access),
NULL_TREE,
gsi_stmt (*gsi));
gsi_insert_after (gsi, ds, GSI_NEW_STMT);
}
if (access->first_child)
{
HOST_WIDE_INT start_offset, chunk_size;
if (bfr
&& host_integerp (TREE_OPERAND (bfr, 1), 1)
&& host_integerp (TREE_OPERAND (bfr, 2), 1))
{
chunk_size = tree_low_cst (TREE_OPERAND (bfr, 1), 1);
start_offset = access->offset
+ tree_low_cst (TREE_OPERAND (bfr, 2), 1);
}
else
start_offset = chunk_size = 0;
generate_subtree_copies (access->first_child, access->base, 0,
start_offset, chunk_size, gsi, write, write,
loc);
}
return true;
}
/* Where scalar replacements of the RHS have been written to when a replacement
of a LHS of an assigments cannot be direclty loaded from a replacement of
the RHS. */
enum unscalarized_data_handling { SRA_UDH_NONE, /* Nothing done so far. */
SRA_UDH_RIGHT, /* Data flushed to the RHS. */
SRA_UDH_LEFT }; /* Data flushed to the LHS. */
/* Store all replacements in the access tree rooted in TOP_RACC either to their
base aggregate if there are unscalarized data or directly to LHS of the
statement that is pointed to by GSI otherwise. */
static enum unscalarized_data_handling
handle_unscalarized_data_in_subtree (struct access *top_racc,
gimple_stmt_iterator *gsi)
{
if (top_racc->grp_unscalarized_data)
{
generate_subtree_copies (top_racc->first_child, top_racc->base, 0, 0, 0,
gsi, false, false,
gimple_location (gsi_stmt (*gsi)));
return SRA_UDH_RIGHT;
}
else
{
tree lhs = gimple_assign_lhs (gsi_stmt (*gsi));
generate_subtree_copies (top_racc->first_child, lhs, top_racc->offset,
0, 0, gsi, false, false,
gimple_location (gsi_stmt (*gsi)));
return SRA_UDH_LEFT;
}
}
/* Try to generate statements to load all sub-replacements in an access subtree
formed by children of LACC from scalar replacements in the TOP_RACC subtree.
If that is not possible, refresh the TOP_RACC base aggregate and load the
accesses from it. LEFT_OFFSET is the offset of the left whole subtree being
copied. NEW_GSI is stmt iterator used for statement insertions after the
original assignment, OLD_GSI is used to insert statements before the
assignment. *REFRESHED keeps the information whether we have needed to
refresh replacements of the LHS and from which side of the assignments this
takes place. */
static void
load_assign_lhs_subreplacements (struct access *lacc, struct access *top_racc,
HOST_WIDE_INT left_offset,
gimple_stmt_iterator *old_gsi,
gimple_stmt_iterator *new_gsi,
enum unscalarized_data_handling *refreshed)
{
location_t loc = gimple_location (gsi_stmt (*old_gsi));
for (lacc = lacc->first_child; lacc; lacc = lacc->next_sibling)
{
HOST_WIDE_INT offset = lacc->offset - left_offset + top_racc->offset;
if (lacc->grp_to_be_replaced)
{
struct access *racc;
gimple stmt;
tree rhs;
racc = find_access_in_subtree (top_racc, offset, lacc->size);
if (racc && racc->grp_to_be_replaced)
{
rhs = get_access_replacement (racc);
if (!useless_type_conversion_p (lacc->type, racc->type))
rhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR, lacc->type, rhs);
if (racc->grp_partial_lhs && lacc->grp_partial_lhs)
rhs = force_gimple_operand_gsi (old_gsi, rhs, true, NULL_TREE,
true, GSI_SAME_STMT);
}
else
{
/* No suitable access on the right hand side, need to load from
the aggregate. See if we have to update it first... */
if (*refreshed == SRA_UDH_NONE)
*refreshed = handle_unscalarized_data_in_subtree (top_racc,
old_gsi);
if (*refreshed == SRA_UDH_LEFT)
rhs = build_ref_for_model (loc, lacc->base, lacc->offset, lacc,
new_gsi, true);
else
rhs = build_ref_for_model (loc, top_racc->base, offset, lacc,
new_gsi, true);
if (lacc->grp_partial_lhs)
rhs = force_gimple_operand_gsi (new_gsi, rhs, true, NULL_TREE,
false, GSI_NEW_STMT);
}
stmt = gimple_build_assign (get_access_replacement (lacc), rhs);
gsi_insert_after (new_gsi, stmt, GSI_NEW_STMT);
gimple_set_location (stmt, loc);
update_stmt (stmt);
sra_stats.subreplacements++;
}
else
{
if (*refreshed == SRA_UDH_NONE
&& lacc->grp_read && !lacc->grp_covered)
*refreshed = handle_unscalarized_data_in_subtree (top_racc,
old_gsi);
if (lacc && lacc->grp_to_be_debug_replaced)
{
gimple ds;
tree drhs;
struct access *racc = find_access_in_subtree (top_racc, offset,
lacc->size);
if (racc && racc->grp_to_be_replaced)
{
if (racc->grp_write)
drhs = get_access_replacement (racc);
else
drhs = NULL;
}
else if (*refreshed == SRA_UDH_LEFT)
drhs = build_debug_ref_for_model (loc, lacc->base, lacc->offset,
lacc);
else if (*refreshed == SRA_UDH_RIGHT)
drhs = build_debug_ref_for_model (loc, top_racc->base, offset,
lacc);
else
drhs = NULL_TREE;
if (drhs
&& !useless_type_conversion_p (lacc->type, TREE_TYPE (drhs)))
drhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR,
lacc->type, drhs);
ds = gimple_build_debug_bind (get_access_replacement (lacc),
drhs, gsi_stmt (*old_gsi));
gsi_insert_after (new_gsi, ds, GSI_NEW_STMT);
}
}
if (lacc->first_child)
load_assign_lhs_subreplacements (lacc, top_racc, left_offset,
old_gsi, new_gsi, refreshed);
}
}
/* Result code for SRA assignment modification. */
enum assignment_mod_result { SRA_AM_NONE, /* nothing done for the stmt */
SRA_AM_MODIFIED, /* stmt changed but not
removed */
SRA_AM_REMOVED }; /* stmt eliminated */
/* Modify assignments with a CONSTRUCTOR on their RHS. STMT contains a pointer
to the assignment and GSI is the statement iterator pointing at it. Returns
the same values as sra_modify_assign. */
static enum assignment_mod_result
sra_modify_constructor_assign (gimple *stmt, gimple_stmt_iterator *gsi)
{
tree lhs = gimple_assign_lhs (*stmt);
struct access *acc;
location_t loc;
acc = get_access_for_expr (lhs);
if (!acc)
return SRA_AM_NONE;
if (gimple_clobber_p (*stmt))
{
/* Remove clobbers of fully scalarized variables, otherwise
do nothing. */
if (acc->grp_covered)
{
unlink_stmt_vdef (*stmt);
gsi_remove (gsi, true);
release_defs (*stmt);
return SRA_AM_REMOVED;
}
else
return SRA_AM_NONE;
}
loc = gimple_location (*stmt);
if (vec_safe_length (CONSTRUCTOR_ELTS (gimple_assign_rhs1 (*stmt))) > 0)
{
/* I have never seen this code path trigger but if it can happen the
following should handle it gracefully. */
if (access_has_children_p (acc))
generate_subtree_copies (acc->first_child, acc->base, 0, 0, 0, gsi,
true, true, loc);
return SRA_AM_MODIFIED;
}
if (acc->grp_covered)
{
init_subtree_with_zero (acc, gsi, false, loc);
unlink_stmt_vdef (*stmt);
gsi_remove (gsi, true);
release_defs (*stmt);
return SRA_AM_REMOVED;
}
else
{
init_subtree_with_zero (acc, gsi, true, loc);
return SRA_AM_MODIFIED;
}
}
/* Create and return a new suitable default definition SSA_NAME for RACC which
is an access describing an uninitialized part of an aggregate that is being
loaded. */
static tree
get_repl_default_def_ssa_name (struct access *racc)
{
gcc_checking_assert (!racc->grp_to_be_replaced &&
!racc->grp_to_be_debug_replaced);
if (!racc->replacement_decl)
racc->replacement_decl = create_access_replacement (racc);
return get_or_create_ssa_default_def (cfun, racc->replacement_decl);
}
/* Return true if REF has an VIEW_CONVERT_EXPR or a COMPONENT_REF with a
bit-field field declaration somewhere in it. */
static inline bool
contains_vce_or_bfcref_p (const_tree ref)
{
while (handled_component_p (ref))
{
if (TREE_CODE (ref) == VIEW_CONVERT_EXPR
|| (TREE_CODE (ref) == COMPONENT_REF
&& DECL_BIT_FIELD (TREE_OPERAND (ref, 1))))
return true;
ref = TREE_OPERAND (ref, 0);
}
return false;
}
/* Examine both sides of the assignment statement pointed to by STMT, replace
them with a scalare replacement if there is one and generate copying of
replacements if scalarized aggregates have been used in the assignment. GSI
is used to hold generated statements for type conversions and subtree
copying. */
static enum assignment_mod_result
sra_modify_assign (gimple *stmt, gimple_stmt_iterator *gsi)
{
struct access *lacc, *racc;
tree lhs, rhs;
bool modify_this_stmt = false;
bool force_gimple_rhs = false;
location_t loc;
gimple_stmt_iterator orig_gsi = *gsi;
if (!gimple_assign_single_p (*stmt))
return SRA_AM_NONE;
lhs = gimple_assign_lhs (*stmt);
rhs = gimple_assign_rhs1 (*stmt);
if (TREE_CODE (rhs) == CONSTRUCTOR)
return sra_modify_constructor_assign (stmt, gsi);
if (TREE_CODE (rhs) == REALPART_EXPR || TREE_CODE (lhs) == REALPART_EXPR
|| TREE_CODE (rhs) == IMAGPART_EXPR || TREE_CODE (lhs) == IMAGPART_EXPR
|| TREE_CODE (rhs) == BIT_FIELD_REF || TREE_CODE (lhs) == BIT_FIELD_REF)
{
modify_this_stmt = sra_modify_expr (gimple_assign_rhs1_ptr (*stmt),
gsi, false);
modify_this_stmt |= sra_modify_expr (gimple_assign_lhs_ptr (*stmt),
gsi, true);
return modify_this_stmt ? SRA_AM_MODIFIED : SRA_AM_NONE;
}
lacc = get_access_for_expr (lhs);
racc = get_access_for_expr (rhs);
if (!lacc && !racc)
return SRA_AM_NONE;
loc = gimple_location (*stmt);
if (lacc && lacc->grp_to_be_replaced)
{
lhs = get_access_replacement (lacc);
gimple_assign_set_lhs (*stmt, lhs);
modify_this_stmt = true;
if (lacc->grp_partial_lhs)
force_gimple_rhs = true;
sra_stats.exprs++;
}
if (racc && racc->grp_to_be_replaced)
{
rhs = get_access_replacement (racc);
modify_this_stmt = true;
if (racc->grp_partial_lhs)
force_gimple_rhs = true;
sra_stats.exprs++;
}
else if (racc
&& !racc->grp_unscalarized_data
&& TREE_CODE (lhs) == SSA_NAME
&& !access_has_replacements_p (racc))
{
rhs = get_repl_default_def_ssa_name (racc);
modify_this_stmt = true;
sra_stats.exprs++;
}
if (modify_this_stmt)
{
if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
{
/* If we can avoid creating a VIEW_CONVERT_EXPR do so.
??? This should move to fold_stmt which we simply should
call after building a VIEW_CONVERT_EXPR here. */
if (AGGREGATE_TYPE_P (TREE_TYPE (lhs))
&& !contains_bitfld_component_ref_p (lhs))
{
lhs = build_ref_for_model (loc, lhs, 0, racc, gsi, false);
gimple_assign_set_lhs (*stmt, lhs);
}
else if (AGGREGATE_TYPE_P (TREE_TYPE (rhs))
&& !contains_vce_or_bfcref_p (rhs))
rhs = build_ref_for_model (loc, rhs, 0, lacc, gsi, false);
if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
{
rhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR, TREE_TYPE (lhs),
rhs);
if (is_gimple_reg_type (TREE_TYPE (lhs))
&& TREE_CODE (lhs) != SSA_NAME)
force_gimple_rhs = true;
}
}
}
if (lacc && lacc->grp_to_be_debug_replaced)
{
tree dlhs = get_access_replacement (lacc);
tree drhs = unshare_expr (rhs);
if (!useless_type_conversion_p (TREE_TYPE (dlhs), TREE_TYPE (drhs)))
{
if (AGGREGATE_TYPE_P (TREE_TYPE (drhs))
&& !contains_vce_or_bfcref_p (drhs))
drhs = build_debug_ref_for_model (loc, drhs, 0, lacc);
if (drhs
&& !useless_type_conversion_p (TREE_TYPE (dlhs),
TREE_TYPE (drhs)))
drhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR,
TREE_TYPE (dlhs), drhs);
}
gimple ds = gimple_build_debug_bind (dlhs, drhs, *stmt);
gsi_insert_before (gsi, ds, GSI_SAME_STMT);
}
/* From this point on, the function deals with assignments in between
aggregates when at least one has scalar reductions of some of its
components. There are three possible scenarios: Both the LHS and RHS have
to-be-scalarized components, 2) only the RHS has or 3) only the LHS has.
In the first case, we would like to load the LHS components from RHS
components whenever possible. If that is not possible, we would like to
read it directly from the RHS (after updating it by storing in it its own
components). If there are some necessary unscalarized data in the LHS,
those will be loaded by the original assignment too. If neither of these
cases happen, the original statement can be removed. Most of this is done
by load_assign_lhs_subreplacements.
In the second case, we would like to store all RHS scalarized components
directly into LHS and if they cover the aggregate completely, remove the
statement too. In the third case, we want the LHS components to be loaded
directly from the RHS (DSE will remove the original statement if it
becomes redundant).
This is a bit complex but manageable when types match and when unions do
not cause confusion in a way that we cannot really load a component of LHS
from the RHS or vice versa (the access representing this level can have
subaccesses that are accessible only through a different union field at a
higher level - different from the one used in the examined expression).
Unions are fun.
Therefore, I specially handle a fourth case, happening when there is a
specific type cast or it is impossible to locate a scalarized subaccess on
the other side of the expression. If that happens, I simply "refresh" the
RHS by storing in it is scalarized components leave the original statement
there to do the copying and then load the scalar replacements of the LHS.
This is what the first branch does. */
if (modify_this_stmt
|| gimple_has_volatile_ops (*stmt)
|| contains_vce_or_bfcref_p (rhs)
|| contains_vce_or_bfcref_p (lhs))
{
if (access_has_children_p (racc))
generate_subtree_copies (racc->first_child, racc->base, 0, 0, 0,
gsi, false, false, loc);
if (access_has_children_p (lacc))
generate_subtree_copies (lacc->first_child, lacc->base, 0, 0, 0,
gsi, true, true, loc);
sra_stats.separate_lhs_rhs_handling++;
/* This gimplification must be done after generate_subtree_copies,
lest we insert the subtree copies in the middle of the gimplified
sequence. */
if (force_gimple_rhs)
rhs = force_gimple_operand_gsi (&orig_gsi, rhs, true, NULL_TREE,
true, GSI_SAME_STMT);
if (gimple_assign_rhs1 (*stmt) != rhs)
{
modify_this_stmt = true;