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re PR c++/82294 (Array of objects with constexpr constructors initialized from space-inefficient memory image)

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PR c++/82294
	PR c++/87436
	* expr.h (categorize_ctor_elements): Add p_unique_nz_elts argument.
	* expr.c (categorize_ctor_elements_1): Likewise.  Compute it like
	p_nz_elts, except don't multiply it by mult.  Adjust recursive call.
	Fix up COMPLEX_CST handling.
	(categorize_ctor_elements): Add p_unique_nz_elts argument, initialize
	it and pass it through to categorize_ctor_elements_1.
	(mostly_zeros_p, all_zeros_p): Adjust categorize_ctor_elements callers.
	* gimplify.c (gimplify_init_constructor): Likewise.  Don't force
	ctor into readonly data section if num_unique_nonzero_elements is
	smaller or equal to 1/8 of num_nonzero_elements and size is >= 64
	bytes.

	* g++.dg/tree-ssa/pr82294.C: New test.
	* g++.dg/tree-ssa/pr87436.C: New test.

From-SVN: r267143
This commit is contained in:
Jakub Jelinek 2018-12-14 20:37:38 +01:00 • committed by Jakub Jelinek
parent faa9232da3
commit 0fca07e31d
7 changed files with 131 additions and 17 deletions
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16
gcc/ChangeLog
View file

@ -1,3 +1,19 @@
2018-12-14 Jakub Jelinek <jakub@redhat.com>
PR c++/82294
PR c++/87436
* expr.h (categorize_ctor_elements): Add p_unique_nz_elts argument.
* expr.c (categorize_ctor_elements_1): Likewise. Compute it like
p_nz_elts, except don't multiply it by mult. Adjust recursive call.
Fix up COMPLEX_CST handling.
(categorize_ctor_elements): Add p_unique_nz_elts argument, initialize
it and pass it through to categorize_ctor_elements_1.
(mostly_zeros_p, all_zeros_p): Adjust categorize_ctor_elements callers.
* gimplify.c (gimplify_init_constructor): Likewise. Don't force
ctor into readonly data section if num_unique_nonzero_elements is
smaller or equal to 1/8 of num_nonzero_elements and size is >= 64
bytes.
2018-12-14 Thomas Preud'homme <thomas.preudhomme@arm.com>
* config/arm/arm.md (arm_movdi): Split if -mslow-flash-data and

58
gcc/expr.c
View file

@ -5945,10 +5945,11 @@ count_type_elements (const_tree type, bool for_ctor_p)
static bool
categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
HOST_WIDE_INT *p_unique_nz_elts,
HOST_WIDE_INT *p_init_elts, bool *p_complete)
{
unsigned HOST_WIDE_INT idx;
HOST_WIDE_INT nz_elts, init_elts, num_fields;
HOST_WIDE_INT nz_elts, unique_nz_elts, init_elts, num_fields;
tree value, purpose, elt_type;
/* Whether CTOR is a valid constant initializer, in accordance with what
@ -5958,6 +5959,7 @@ categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
bool const_p = const_from_elts_p ? true : TREE_STATIC (ctor);
nz_elts = 0;
unique_nz_elts = 0;
init_elts = 0;
num_fields = 0;
elt_type = NULL_TREE;
@ -5982,12 +5984,13 @@ categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
{
case CONSTRUCTOR:
{
HOST_WIDE_INT nz = 0, ic = 0;
HOST_WIDE_INT nz = 0, unz = 0, ic = 0;
bool const_elt_p = categorize_ctor_elements_1 (value, &nz, &ic,
p_complete);
bool const_elt_p = categorize_ctor_elements_1 (value, &nz, &unz,
&ic, p_complete);
nz_elts += mult * nz;
unique_nz_elts += unz;
init_elts += mult * ic;
if (const_from_elts_p && const_p)
@ -5999,21 +6002,31 @@ categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
case REAL_CST:
case FIXED_CST:
if (!initializer_zerop (value))
nz_elts += mult;
{
nz_elts += mult;
unique_nz_elts++;
}
init_elts += mult;
break;
case STRING_CST:
nz_elts += mult * TREE_STRING_LENGTH (value);
unique_nz_elts += TREE_STRING_LENGTH (value);
init_elts += mult * TREE_STRING_LENGTH (value);
break;
case COMPLEX_CST:
if (!initializer_zerop (TREE_REALPART (value)))
nz_elts += mult;
{
nz_elts += mult;
unique_nz_elts++;
}
if (!initializer_zerop (TREE_IMAGPART (value)))
nz_elts += mult;
init_elts += mult;
{
nz_elts += mult;
unique_nz_elts++;
}
init_elts += 2 * mult;
break;
case VECTOR_CST:
@ -6025,7 +6038,10 @@ categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
{
tree v = VECTOR_CST_ELT (value, i);
if (!initializer_zerop (v))
nz_elts += mult;
{
nz_elts += mult;
unique_nz_elts++;
}
init_elts += mult;
}
}
@ -6035,6 +6051,7 @@ categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
{
HOST_WIDE_INT tc = count_type_elements (elt_type, false);
nz_elts += mult * tc;
unique_nz_elts += tc;
init_elts += mult * tc;
if (const_from_elts_p && const_p)
@ -6054,6 +6071,7 @@ categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
*p_complete = false;
*p_nz_elts += nz_elts;
*p_unique_nz_elts += unique_nz_elts;
*p_init_elts += init_elts;
return const_p;
@ -6062,6 +6080,11 @@ categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
/* Examine CTOR to discover:
* how many scalar fields are set to nonzero values,
and place it in *P_NZ_ELTS;
* the same, but counting RANGE_EXPRs as multiplier of 1 instead of
high - low + 1 (this can be useful for callers to determine ctors
that could be cheaply initialized with - perhaps nested - loops
compared to copied from huge read-only data),
and place it in *P_UNIQUE_NZ_ELTS;
* how many scalar fields in total are in CTOR,
and place it in *P_ELT_COUNT.
* whether the constructor is complete -- in the sense that every
@ -6073,13 +6096,16 @@ categorize_ctor_elements_1 (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
bool
categorize_ctor_elements (const_tree ctor, HOST_WIDE_INT *p_nz_elts,
HOST_WIDE_INT *p_unique_nz_elts,
HOST_WIDE_INT *p_init_elts, bool *p_complete)
{
*p_nz_elts = 0;
*p_unique_nz_elts = 0;
*p_init_elts = 0;
*p_complete = true;
return categorize_ctor_elements_1 (ctor, p_nz_elts, p_init_elts, p_complete);
return categorize_ctor_elements_1 (ctor, p_nz_elts, p_unique_nz_elts,
p_init_elts, p_complete);
}
/* TYPE is initialized by a constructor with NUM_ELTS elements, the last
@ -6110,17 +6136,18 @@ complete_ctor_at_level_p (const_tree type, HOST_WIDE_INT num_elts,
return count_type_elements (type, true) == num_elts;
}
/* Return 1 if EXP contains mostly (3/4) zeros. */
/* Return 1 if EXP contains mostly (3/4) zeros. */
static int
mostly_zeros_p (const_tree exp)
{
if (TREE_CODE (exp) == CONSTRUCTOR)
{
HOST_WIDE_INT nz_elts, init_elts;
HOST_WIDE_INT nz_elts, unz_elts, init_elts;
bool complete_p;
categorize_ctor_elements (exp, &nz_elts, &init_elts, &complete_p);
categorize_ctor_elements (exp, &nz_elts, &unz_elts, &init_elts,
&complete_p);
return !complete_p || nz_elts < init_elts / 4;
}
@ -6134,10 +6161,11 @@ all_zeros_p (const_tree exp)
{
if (TREE_CODE (exp) == CONSTRUCTOR)
{
HOST_WIDE_INT nz_elts, init_elts;
HOST_WIDE_INT nz_elts, unz_elts, init_elts;
bool complete_p;
categorize_ctor_elements (exp, &nz_elts, &init_elts, &complete_p);
categorize_ctor_elements (exp, &nz_elts, &unz_elts, &init_elts,
&complete_p);
return nz_elts == 0;
}

3
gcc/expr.h
View file

@ -309,7 +309,8 @@ extern bool can_move_by_pieces (unsigned HOST_WIDE_INT, unsigned int);
extern unsigned HOST_WIDE_INT highest_pow2_factor (const_tree);
extern bool categorize_ctor_elements (const_tree, HOST_WIDE_INT *,
HOST_WIDE_INT *, bool *);
HOST_WIDE_INT *, HOST_WIDE_INT *,
bool *);
extern void expand_operands (tree, tree, rtx, rtx*, rtx*,
enum expand_modifier);

26
gcc/gimplify.c
View file

@ -4778,7 +4778,15 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
{
struct gimplify_init_ctor_preeval_data preeval_data;
HOST_WIDE_INT num_ctor_elements, num_nonzero_elements;
HOST_WIDE_INT num_unique_nonzero_elements;
bool cleared, complete_p, valid_const_initializer;
/* Use readonly data for initializers of this or smaller size
regardless of the num_nonzero_elements / num_unique_nonzero_elements
ratio. */
const HOST_WIDE_INT min_unique_size = 64;
/* If num_nonzero_elements / num_unique_nonzero_elements ratio
is smaller than this, use readonly data. */
const int unique_nonzero_ratio = 8;
/* Aggregate types must lower constructors to initialization of
individual elements. The exception is that a CONSTRUCTOR node
@ -4795,6 +4803,7 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
can only do so if it known to be a valid constant initializer. */
valid_const_initializer
= categorize_ctor_elements (ctor, &num_nonzero_elements,
&num_unique_nonzero_elements,
&num_ctor_elements, &complete_p);
/* If a const aggregate variable is being initialized, then it
@ -4803,7 +4812,15 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
&& num_nonzero_elements > 1
&& TREE_READONLY (object)
&& VAR_P (object)
&& (flag_merge_constants >= 2 || !TREE_ADDRESSABLE (object)))
&& (flag_merge_constants >= 2 || !TREE_ADDRESSABLE (object))
/* For ctors that have many repeated nonzero elements
represented through RANGE_EXPRs, prefer initializing
those through runtime loops over copies of large amounts
of data from readonly data section. */
&& (num_unique_nonzero_elements
> num_nonzero_elements / unique_nonzero_ratio
|| ((unsigned HOST_WIDE_INT) int_size_in_bytes (type)
<= (unsigned HOST_WIDE_INT) min_unique_size)))
{
if (notify_temp_creation)
return GS_ERROR;
@ -4896,6 +4913,13 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
is so large as to make individual moves inefficient. */
if (size > 0
&& num_nonzero_elements > 1
/* For ctors that have many repeated nonzero elements
represented through RANGE_EXPRs, prefer initializing
those through runtime loops over copies of large amounts
of data from readonly data section. */
&& (num_unique_nonzero_elements
> num_nonzero_elements / unique_nonzero_ratio
|| size <= min_unique_size)
&& (size < num_nonzero_elements
|| !can_move_by_pieces (size, align)))
{

7
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,10 @@
2018-12-14 Jakub Jelinek <jakub@redhat.com>
PR c++/82294
PR c++/87436
* g++.dg/tree-ssa/pr82294.C: New test.
* g++.dg/tree-ssa/pr87436.C: New test.
2018-11-14 Thomas Preud'homme <thomas.preudhomme@arm.com>
* gcc.target/arm/thumb2-slow-flash-data-2.c: Require arm_fp_ok

13
gcc/testsuite/g++.dg/tree-ssa/pr82294.C Normal file
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@ -0,0 +1,13 @@
// PR c++/82294
// { dg-do compile { target c++11 } }
// { dg-options "-O2 -fdump-tree-gimple" }
// Verify we don't "optimize" the ctor as copying a 1KB .rodata
// object into the variable. It is better to initialize it through
// a loop.
// { dg-final { scan-tree-dump-not "this->arr = " "gimple" } }
struct S { int x; explicit constexpr S (); };
constexpr S::S () : x{7} {}
struct T { S arr[256]; explicit T (); };
T::T () {}

25
gcc/testsuite/g++.dg/tree-ssa/pr87436.C Normal file
View file

@ -0,0 +1,25 @@
// PR c++/87436
// { dg-do compile { target { c++11 && size32plus } } }
// { dg-options "-O2 -fdump-tree-gimple" }
// Verify we don't "optimize" the ctor as copying a 384MB .rodata
// object into the variable. It is better to initialize it through
// two nested loops.
// { dg-final { scan-tree-dump-not "this->arr = " "gimple" } }
struct S {
int a = -1;
short b = 3;
int x = 0;
int y = 1;
int z = 42;
float f = 0.123f;
};
struct T { S arr[4096][4096]; };
T *
foo ()
{
return new T;
}