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re PR target/92038 (Extremely inefficient x86_64 code for trivally copyable types passed in registers.) 

PR target/92038
	* gimple-ssa-store-merging.c (find_constituent_stores): For return
	value only, return non-NULL if there is a single non-clobber
	constituent store even if there are constituent clobbers and return
	one of clobber constituent stores if all constituent stores are
	clobbers.
	(split_group): Handle clobbers.
	(imm_store_chain_info::output_merged_store): When computing
	bzero_first, look after all clobbers at the start.  Don't count
	clobber stmts in orig_num_stmts, except if the first orig store is
	a clobber covering the whole area and split_stores cover the whole
	area, consider equal number of stmts ok.  Punt if split_stores
	contains only ->orig stores and their number plus number of original
	clobbers is equal to original number of stmts.  For ->orig, look past
	clobbers in the constituent stores.
	(imm_store_chain_info::output_merged_stores): Don't remove clobber
	stmts.
	(rhs_valid_for_store_merging_p): Don't return false for clobber stmt
	rhs.
	(store_valid_for_store_merging_p): Allow clobber stmts.
	(verify_clear_bit_region_be): Fix up a thinko in function comment.

	* g++.dg/opt/store-merging-1.C: New test.
	* g++.dg/opt/store-merging-2.C: New test.
	* g++.dg/opt/store-merging-3.C: New test.

From-SVN: r277963
This commit is contained in:
Jakub Jelinek 2019-11-08 11:53:50 +01:00 committed by Jakub Jelinek
parent aea86742ce
commit 5384a80270
6 changed files with 219 additions and 27 deletions
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22
gcc/ChangeLog
View File

@ -1,5 +1,27 @@
2019-11-08 Jakub Jelinek <jakub@redhat.com>
PR target/92038
* gimple-ssa-store-merging.c (find_constituent_stores): For return
value only, return non-NULL if there is a single non-clobber
constituent store even if there are constituent clobbers and return
one of clobber constituent stores if all constituent stores are
clobbers.
(split_group): Handle clobbers.
(imm_store_chain_info::output_merged_store): When computing
bzero_first, look after all clobbers at the start. Don't count
clobber stmts in orig_num_stmts, except if the first orig store is
a clobber covering the whole area and split_stores cover the whole
area, consider equal number of stmts ok. Punt if split_stores
contains only ->orig stores and their number plus number of original
clobbers is equal to original number of stmts. For ->orig, look past
clobbers in the constituent stores.
(imm_store_chain_info::output_merged_stores): Don't remove clobber
stmts.
(rhs_valid_for_store_merging_p): Don't return false for clobber stmt
rhs.
(store_valid_for_store_merging_p): Allow clobber stmts.
(verify_clear_bit_region_be): Fix up a thinko in function comment.
PR c++/92384
* function.c (assign_parm_setup_block, assign_parm_setup_stack): Don't
copy TYPE_EMPTY_P arguments from data->entry_parm to data->stack_parm

192
gcc/gimple-ssa-store-merging.c
View File

@ -3110,7 +3110,8 @@ split_store::split_store (unsigned HOST_WIDE_INT bp,
/* Record all stores in GROUP that write to the region starting at BITPOS and
is of size BITSIZE. Record infos for such statements in STORES if
non-NULL. The stores in GROUP must be sorted by bitposition. Return INFO
if there is exactly one original store in the range. */
if there is exactly one original store in the range (in that case ignore
clobber stmts, unless there are only clobber stmts). */
static store_immediate_info *
find_constituent_stores (class merged_store_group *group,
@ -3146,16 +3147,24 @@ find_constituent_stores (class merged_store_group *group,
if (stmt_start >= end)
return ret;
if (gimple_clobber_p (info->stmt))
{
if (stores)
stores->safe_push (info);
if (ret == NULL)
ret = info;
continue;
}
if (stores)
{
stores->safe_push (info);
if (ret)
if (ret && !gimple_clobber_p (ret->stmt))
{
ret = NULL;
second = true;
}
}
else if (ret)
else if (ret && !gimple_clobber_p (ret->stmt))
return NULL;
if (!second)
ret = info;
@ -3347,13 +3356,17 @@ split_group (merged_store_group *group, bool allow_unaligned_store,
if (bzero_first)
{
first = 1;
store_immediate_info *gstore;
FOR_EACH_VEC_ELT (group->stores, first, gstore)
if (!gimple_clobber_p (gstore->stmt))
break;
++first;
ret = 1;
if (split_stores)
{
split_store *store
= new split_store (bytepos, group->stores[0]->bitsize, align_base);
store->orig_stores.safe_push (group->stores[0]);
= new split_store (bytepos, gstore->bitsize, align_base);
store->orig_stores.safe_push (gstore);
store->orig = true;
any_orig = true;
split_stores->safe_push (store);
@ -3377,6 +3390,7 @@ split_group (merged_store_group *group, bool allow_unaligned_store,
unsigned HOST_WIDE_INT align_bitpos
= (try_bitpos - align_base) & (group_align - 1);
unsigned HOST_WIDE_INT align = group_align;
bool found_orig = false;
if (align_bitpos)
align = least_bit_hwi (align_bitpos);
if (!allow_unaligned_store)
@ -3408,7 +3422,7 @@ split_group (merged_store_group *group, bool allow_unaligned_store,
}
store_immediate_info *info
= find_constituent_stores (group, NULL, &first, try_bitpos, try_size);
if (info)
if (info && !gimple_clobber_p (info->stmt))
{
/* If there is just one original statement for the range, see if
we can just reuse the original store which could be even larger
@ -3419,8 +3433,30 @@ split_group (merged_store_group *group, bool allow_unaligned_store,
stmt_end - try_bitpos);
if (info && info->bitpos >= try_bitpos)
{
try_size = stmt_end - try_bitpos;
goto found;
store_immediate_info *info2 = NULL;
unsigned int first_copy = first;
if (info->bitpos > try_bitpos
&& stmt_end - try_bitpos <= try_size)
{
info2 = find_constituent_stores (group, NULL, &first_copy,
try_bitpos,
info->bitpos - try_bitpos);
gcc_assert (info2 == NULL || gimple_clobber_p (info2->stmt));
}
if (info2 == NULL && stmt_end - try_bitpos < try_size)
{
info2 = find_constituent_stores (group, NULL, &first_copy,
stmt_end,
(try_bitpos + try_size)
- stmt_end);
gcc_assert (info2 == NULL || gimple_clobber_p (info2->stmt));
}
if (info2 == NULL)
{
try_size = stmt_end - try_bitpos;
found_orig = true;
goto found;
}
}
}
@ -3435,7 +3471,7 @@ split_group (merged_store_group *group, bool allow_unaligned_store,
&& (!bzero_first
|| group->val[try_pos - bytepos + nonmasked - 1] != 0))
break;
if (nonmasked == 0)
if (nonmasked == 0 || (info && gimple_clobber_p (info->stmt)))
{
/* If entire try_size range is padding, skip it. */
try_pos += try_size / BITS_PER_UNIT;
@ -3483,8 +3519,14 @@ split_group (merged_store_group *group, bool allow_unaligned_store,
info = find_constituent_stores (group, &store->orig_stores,
&first, try_bitpos, try_size);
if (info
&& !gimple_clobber_p (info->stmt)
&& info->bitpos >= try_bitpos
&& info->bitpos + info->bitsize <= try_bitpos + try_size)
&& info->bitpos + info->bitsize <= try_bitpos + try_size
&& (store->orig_stores.length () == 1
|| found_orig
|| (info->bitpos == try_bitpos
&& (info->bitpos + info->bitsize
== try_bitpos + try_size))))
{
store->orig = true;
any_orig = true;
@ -3671,14 +3713,32 @@ imm_store_chain_info::output_merged_store (merged_store_group *group)
= !STRICT_ALIGNMENT && PARAM_VALUE (PARAM_STORE_MERGING_ALLOW_UNALIGNED);
bool allow_unaligned_load = allow_unaligned_store;
bool bzero_first = false;
if (group->stores[0]->rhs_code == INTEGER_CST
&& TREE_CODE (gimple_assign_rhs1 (group->stores[0]->stmt)) == CONSTRUCTOR
&& CONSTRUCTOR_NELTS (gimple_assign_rhs1 (group->stores[0]->stmt)) == 0
&& group->start == group->stores[0]->bitpos
&& group->width == group->stores[0]->bitsize
&& (group->start % BITS_PER_UNIT) == 0
&& (group->width % BITS_PER_UNIT) == 0)
bzero_first = true;
store_immediate_info *store;
unsigned int num_clobber_stmts = 0;
if (group->stores[0]->rhs_code == INTEGER_CST)
{
FOR_EACH_VEC_ELT (group->stores, i, store)
if (gimple_clobber_p (store->stmt))
num_clobber_stmts++;
else if (TREE_CODE (gimple_assign_rhs1 (store->stmt)) == CONSTRUCTOR
&& CONSTRUCTOR_NELTS (gimple_assign_rhs1 (store->stmt)) == 0
&& group->start == store->bitpos
&& group->width == store->bitsize
&& (group->start % BITS_PER_UNIT) == 0
&& (group->width % BITS_PER_UNIT) == 0)
{
bzero_first = true;
break;
}
else
break;
FOR_EACH_VEC_ELT_FROM (group->stores, i, store, i)
if (gimple_clobber_p (store->stmt))
num_clobber_stmts++;
if (num_clobber_stmts == orig_num_stmts)
return false;
orig_num_stmts -= num_clobber_stmts;
}
if (allow_unaligned_store || bzero_first)
{
/* If unaligned stores are allowed, see how many stores we'd emit
@ -3710,8 +3770,35 @@ imm_store_chain_info::output_merged_store (merged_store_group *group)
split_group (group, allow_unaligned_store, allow_unaligned_load, bzero_first,
&split_stores, &total_orig, &total_new);
if (split_stores.length () >= orig_num_stmts)
/* Determine if there is a clobber covering the whole group at the start,
followed by proposed split stores that cover the whole group. In that
case, prefer the transformation even if
split_stores.length () == orig_num_stmts. */
bool clobber_first = false;
if (num_clobber_stmts
&& gimple_clobber_p (group->stores[0]->stmt)
&& group->start == group->stores[0]->bitpos
&& group->width == group->stores[0]->bitsize
&& (group->start % BITS_PER_UNIT) == 0
&& (group->width % BITS_PER_UNIT) == 0)
{
clobber_first = true;
unsigned HOST_WIDE_INT pos = group->start / BITS_PER_UNIT;
FOR_EACH_VEC_ELT (split_stores, i, split_store)
if (split_store->bytepos != pos)
{
clobber_first = false;
break;
}
else
pos += split_store->size / BITS_PER_UNIT;
if (pos != (group->start + group->width) / BITS_PER_UNIT)
clobber_first = false;
}
if (split_stores.length () >= orig_num_stmts + clobber_first)
{
/* We didn't manage to reduce the number of statements. Bail out. */
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Exceeded original number of stmts (%u)."
@ -3734,6 +3821,36 @@ imm_store_chain_info::output_merged_store (merged_store_group *group)
delete split_store;
return false;
}
if (group->stores[0]->rhs_code == INTEGER_CST)
{
bool all_orig = true;
FOR_EACH_VEC_ELT (split_stores, i, split_store)
if (!split_store->orig)
{
all_orig = false;
break;
}
if (all_orig)
{
unsigned int cnt = split_stores.length ();
store_immediate_info *store;
FOR_EACH_VEC_ELT (group->stores, i, store)
if (gimple_clobber_p (store->stmt))
++cnt;
/* Punt if we wouldn't make any real changes, i.e. keep all
orig stmts + all clobbers. */
if (cnt == group->stores.length ())
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Exceeded original number of stmts (%u)."
" Not profitable to emit new sequence.\n",
orig_num_stmts);
FOR_EACH_VEC_ELT (split_stores, i, split_store)
delete split_store;
return false;
}
}
}
gimple_stmt_iterator last_gsi = gsi_for_stmt (group->last_stmt);
gimple_seq seq = NULL;
@ -3742,6 +3859,13 @@ imm_store_chain_info::output_merged_store (merged_store_group *group)
new_vuse = gimple_vuse (group->last_stmt);
tree bswap_res = NULL_TREE;
/* Clobbers are not removed. */
if (gimple_clobber_p (group->last_stmt))
{
new_vuse = make_ssa_name (gimple_vop (cfun), group->last_stmt);
gimple_set_vdef (group->last_stmt, new_vuse);
}
if (group->stores[0]->rhs_code == LROTATE_EXPR
|| group->stores[0]->rhs_code == NOP_EXPR)
{
@ -3865,9 +3989,17 @@ imm_store_chain_info::output_merged_store (merged_store_group *group)
location_t loc;
if (split_store->orig)
{
/* If there is just a single constituent store which covers
the whole area, just reuse the lhs and rhs. */
gimple *orig_stmt = split_store->orig_stores[0]->stmt;
/* If there is just a single non-clobber constituent store
which covers the whole area, just reuse the lhs and rhs. */
gimple *orig_stmt = NULL;
store_immediate_info *store;
unsigned int j;
FOR_EACH_VEC_ELT (split_store->orig_stores, j, store)
if (!gimple_clobber_p (store->stmt))
{
orig_stmt = store->stmt;
break;
}
dest = gimple_assign_lhs (orig_stmt);
src = gimple_assign_rhs1 (orig_stmt);
loc = gimple_location (orig_stmt);
@ -4194,6 +4326,9 @@ imm_store_chain_info::output_merged_store (merged_store_group *group)
print_gimple_seq (dump_file, seq, 0, TDF_VOPS | TDF_MEMSYMS);
}
if (gimple_clobber_p (group->last_stmt))
update_stmt (group->last_stmt);
if (group->lp_nr > 0)
{
/* We're going to insert a sequence of (potentially) throwing stores
@ -4279,6 +4414,10 @@ imm_store_chain_info::output_merged_stores ()
{
gimple *stmt = store->stmt;
gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
/* Don't remove clobbers, they are still useful even if
everything is overwritten afterwards. */
if (gimple_clobber_p (stmt))
continue;
gsi_remove (&gsi, true);
if (store->lp_nr)
remove_stmt_from_eh_lp (stmt);
@ -4361,7 +4500,6 @@ rhs_valid_for_store_merging_p (tree rhs)
{
unsigned HOST_WIDE_INT size;
if (TREE_CODE (rhs) == CONSTRUCTOR
&& !TREE_CLOBBER_P (rhs)
&& CONSTRUCTOR_NELTS (rhs) == 0
&& TYPE_SIZE_UNIT (TREE_TYPE (rhs))
&& tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (rhs))))
@ -4794,7 +4932,7 @@ store_valid_for_store_merging_p (gimple *stmt)
return gimple_assign_single_p (stmt)
&& gimple_vdef (stmt)
&& lhs_valid_for_store_merging_p (gimple_assign_lhs (stmt))
&& !gimple_has_volatile_ops (stmt);
&& (!gimple_has_volatile_ops (stmt) || gimple_clobber_p (stmt));
}
enum basic_block_status { BB_INVALID, BB_VALID, BB_EXTENDED_VALID };
@ -4875,7 +5013,7 @@ pass_store_merging::execute (function *fun)
if (is_gimple_debug (stmt))
continue;
if (gimple_has_volatile_ops (stmt))
if (gimple_has_volatile_ops (stmt) && !gimple_clobber_p (stmt))
{
/* Terminate all chains. */
if (dump_file && (dump_flags & TDF_DETAILS))
@ -5022,7 +5160,7 @@ verify_clear_bit_region (void)
verify_array_eq (in, expected, sizeof in);
}
/* Test verify_clear_bit_region_be that it clears exactly the bits asked and
/* Test clear_bit_region_be that it clears exactly the bits asked and
nothing more. */
static void

5
gcc/testsuite/ChangeLog
View File

@ -1,5 +1,10 @@
2019-11-08 Jakub Jelinek <jakub@redhat.com>
PR target/92038
* g++.dg/opt/store-merging-1.C: New test.
* g++.dg/opt/store-merging-2.C: New test.
* g++.dg/opt/store-merging-3.C: New test.
PR c++/92384
* g++.dg/torture/pr92384.C: New test.

9
gcc/testsuite/g++.dg/opt/store-merging-1.C Normal file
View File

@ -0,0 +1,9 @@
// PR target/92038
// { dg-do compile { target int32 } }
// { dg-require-effective-target store_merge }
// { dg-options "-O2 -flifetime-dse=2 -fdump-tree-store-merging-details" }
// { dg-final { scan-tree-dump "New sequence of \[12] stores to replace old one of 2 stores" "store-merging" } }
struct S { S () : a (0), b (0) {} int a; char b; char c[3]; };
void foo (struct S);
void bar (void) { struct S s; foo (s); }

10
gcc/testsuite/g++.dg/opt/store-merging-2.C Normal file
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@ -0,0 +1,10 @@
// PR target/92038
// { dg-do compile { target int32 } }
// { dg-require-effective-target store_merge }
// { dg-options "-O2 -flifetime-dse=2 -fdump-tree-store-merging-details" }
// { dg-final { scan-tree-dump "New sequence of 2 stores to replace old one of 3 stores" "store-merging" } }
struct T { char a[128]; };
struct S { S () : a () { a.a[12] = 0; a.a[13] = 1; a.a[14] = 0; a.a[15] = 6; } T a; };
void foo (S &);
void bar (void) { S s; foo (s); }

8
gcc/testsuite/g++.dg/opt/store-merging-3.C Normal file
View File

@ -0,0 +1,8 @@
// PR target/92038
// { dg-do compile }
// { dg-options "-O2 -flifetime-dse=2" }
struct A { A (int); int a; };
struct B { B () : b(0) {} A b; };
struct C { C () : c () {} bool c; B d; };
void foo () { C d; }