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openmp: Add support for strict modifier on grainsize/num_tasks clauses

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With strict: modifier on these clauses, the standard is explicit about
how many iterations (and which) each generated task of taskloop directive
should contain.  For num_tasks it actually matches what we were already
implementing, but for grainsize it does not (and even violates the old
rule - without strict it requires that the number of iterations (unspecified
which exactly) handled by each generated task is >= grainsize argument and
< 2 * grainsize argument, with strict: it requires that each generated
task handles exactly == grainsize argument iterations, except for the
generated task handling the last iteration which can handles <= grainsize
iterations).

The following patch implements it for C and C++.

2021-08-23  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* tree.h (OMP_CLAUSE_GRAINSIZE_STRICT): Define.
	(OMP_CLAUSE_NUM_TASKS_STRICT): Define.
	* tree-pretty-print.c (dump_omp_clause) <case OMP_CLAUSE_GRAINSIZE,
	case OMP_CLAUSE_NUM_TASKS>: Print strict: modifier.
	* omp-expand.c (expand_task_call): Use GOMP_TASK_FLAG_STRICT in iflags
	if either grainsize or num_tasks clause has the strict modifier.
gcc/c/
	* c-parser.c (c_parser_omp_clause_num_tasks,
	c_parser_omp_clause_grainsize): Parse the optional strict: modifier.
gcc/cp/
	* parser.c (cp_parser_omp_clause_num_tasks,
	cp_parser_omp_clause_grainsize): Parse the optional strict: modifier.
include/
	* gomp-constants.h (GOMP_TASK_FLAG_STRICT): Define.
libgomp/
	* taskloop.c (GOMP_taskloop): Handle GOMP_TASK_FLAG_STRICT.
	* testsuite/libgomp.c-c++-common/taskloop-4.c (main): Fix up comment.
	* testsuite/libgomp.c-c++-common/taskloop-5.c: New test.
This commit is contained in:
Jakub Jelinek 2021-08-23 10:16:24 +02:00
parent 6f1a3668f5
commit 3bc75533d1
9 changed files with 245 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

34
gcc/c/c-parser.c
View file

@ -13786,7 +13786,10 @@ c_parser_omp_clause_num_threads (c_parser *parser, tree list)
}
/* OpenMP 4.5:
num_tasks ( expression ) */
num_tasks ( expression )
OpenMP 5.1:
num_tasks ( strict : expression ) */
static tree
c_parser_omp_clause_num_tasks (c_parser *parser, tree list)
@ -13795,6 +13798,17 @@ c_parser_omp_clause_num_tasks (c_parser *parser, tree list)
matching_parens parens;
if (parens.require_open (parser))
{
bool strict = false;
if (c_parser_next_token_is (parser, CPP_NAME)
&& c_parser_peek_2nd_token (parser)->type == CPP_COLON
&& strcmp (IDENTIFIER_POINTER (c_parser_peek_token (parser)->value),
"strict") == 0)
{
strict = true;
c_parser_consume_token (parser);
c_parser_consume_token (parser);
}
location_t expr_loc = c_parser_peek_token (parser)->location;
c_expr expr = c_parser_expr_no_commas (parser, NULL);
expr = convert_lvalue_to_rvalue (expr_loc, expr, false, true);
@ -13824,6 +13838,7 @@ c_parser_omp_clause_num_tasks (c_parser *parser, tree list)
c = build_omp_clause (num_tasks_loc, OMP_CLAUSE_NUM_TASKS);
OMP_CLAUSE_NUM_TASKS_EXPR (c) = t;
OMP_CLAUSE_NUM_TASKS_STRICT (c) = strict;
OMP_CLAUSE_CHAIN (c) = list;
list = c;
}
@ -13832,7 +13847,10 @@ c_parser_omp_clause_num_tasks (c_parser *parser, tree list)
}
/* OpenMP 4.5:
grainsize ( expression ) */
grainsize ( expression )
OpenMP 5.1:
grainsize ( strict : expression ) */
static tree
c_parser_omp_clause_grainsize (c_parser *parser, tree list)
@ -13841,6 +13859,17 @@ c_parser_omp_clause_grainsize (c_parser *parser, tree list)
matching_parens parens;
if (parens.require_open (parser))
{
bool strict = false;
if (c_parser_next_token_is (parser, CPP_NAME)
&& c_parser_peek_2nd_token (parser)->type == CPP_COLON
&& strcmp (IDENTIFIER_POINTER (c_parser_peek_token (parser)->value),
"strict") == 0)
{
strict = true;
c_parser_consume_token (parser);
c_parser_consume_token (parser);
}
location_t expr_loc = c_parser_peek_token (parser)->location;
c_expr expr = c_parser_expr_no_commas (parser, NULL);
expr = convert_lvalue_to_rvalue (expr_loc, expr, false, true);
@ -13870,6 +13899,7 @@ c_parser_omp_clause_grainsize (c_parser *parser, tree list)
c = build_omp_clause (grainsize_loc, OMP_CLAUSE_GRAINSIZE);
OMP_CLAUSE_GRAINSIZE_EXPR (c) = t;
OMP_CLAUSE_GRAINSIZE_STRICT (c) = strict;
OMP_CLAUSE_CHAIN (c) = list;
list = c;
}

38
gcc/cp/parser.c
View file

@ -37237,7 +37237,10 @@ cp_parser_omp_clause_num_threads (cp_parser *parser, tree list,
}
/* OpenMP 4.5:
num_tasks ( expression ) */
num_tasks ( expression )
OpenMP 5.1:
num_tasks ( strict : expression ) */
static tree
cp_parser_omp_clause_num_tasks (cp_parser *parser, tree list,
@ -37249,6 +37252,19 @@ cp_parser_omp_clause_num_tasks (cp_parser *parser, tree list,
if (!parens.require_open (parser))
return list;
bool strict = false;
if (cp_lexer_next_token_is (parser->lexer, CPP_NAME)
&& cp_lexer_nth_token_is (parser->lexer, 2, CPP_COLON))
{
tree id = cp_lexer_peek_token (parser->lexer)->u.value;
if (!strcmp (IDENTIFIER_POINTER (id), "strict"))
{
strict = true;
cp_lexer_consume_token (parser->lexer);
cp_lexer_consume_token (parser->lexer);
}
}
t = cp_parser_assignment_expression (parser);
if (t == error_mark_node
@ -37262,13 +37278,17 @@ cp_parser_omp_clause_num_tasks (cp_parser *parser, tree list,
c = build_omp_clause (location, OMP_CLAUSE_NUM_TASKS);
OMP_CLAUSE_NUM_TASKS_EXPR (c) = t;
OMP_CLAUSE_NUM_TASKS_STRICT (c) = strict;
OMP_CLAUSE_CHAIN (c) = list;
return c;
}
/* OpenMP 4.5:
grainsize ( expression ) */
grainsize ( expression )
OpenMP 5.1:
grainsize ( strict : expression ) */
static tree
cp_parser_omp_clause_grainsize (cp_parser *parser, tree list,
@ -37280,6 +37300,19 @@ cp_parser_omp_clause_grainsize (cp_parser *parser, tree list,
if (!parens.require_open (parser))
return list;
bool strict = false;
if (cp_lexer_next_token_is (parser->lexer, CPP_NAME)
&& cp_lexer_nth_token_is (parser->lexer, 2, CPP_COLON))
{
tree id = cp_lexer_peek_token (parser->lexer)->u.value;
if (!strcmp (IDENTIFIER_POINTER (id), "strict"))
{
strict = true;
cp_lexer_consume_token (parser->lexer);
cp_lexer_consume_token (parser->lexer);
}
}
t = cp_parser_assignment_expression (parser);
if (t == error_mark_node
@ -37293,6 +37326,7 @@ cp_parser_omp_clause_grainsize (cp_parser *parser, tree list,
c = build_omp_clause (location, OMP_CLAUSE_GRAINSIZE);
OMP_CLAUSE_GRAINSIZE_EXPR (c) = t;
OMP_CLAUSE_GRAINSIZE_STRICT (c) = strict;
OMP_CLAUSE_CHAIN (c) = list;
return c;

8
gcc/omp-expand.c
View file

@ -791,13 +791,19 @@ expand_task_call (struct omp_region *region, basic_block bb,
tree tclauses = gimple_omp_for_clauses (g);
num_tasks = omp_find_clause (tclauses, OMP_CLAUSE_NUM_TASKS);
if (num_tasks)
num_tasks = OMP_CLAUSE_NUM_TASKS_EXPR (num_tasks);
{
if (OMP_CLAUSE_NUM_TASKS_STRICT (num_tasks))
iflags |= GOMP_TASK_FLAG_STRICT;
num_tasks = OMP_CLAUSE_NUM_TASKS_EXPR (num_tasks);
}
else
{
num_tasks = omp_find_clause (tclauses, OMP_CLAUSE_GRAINSIZE);
if (num_tasks)
{
iflags |= GOMP_TASK_FLAG_GRAINSIZE;
if (OMP_CLAUSE_GRAINSIZE_STRICT (num_tasks))
iflags |= GOMP_TASK_FLAG_STRICT;
num_tasks = OMP_CLAUSE_GRAINSIZE_EXPR (num_tasks);
}
else

4
gcc/tree-pretty-print.c
View file

@ -1066,6 +1066,8 @@ dump_omp_clause (pretty_printer *pp, tree clause, int spc, dump_flags_t flags)
case OMP_CLAUSE_GRAINSIZE:
pp_string (pp, "grainsize(");
if (OMP_CLAUSE_GRAINSIZE_STRICT (clause))
pp_string (pp, "strict:");
dump_generic_node (pp, OMP_CLAUSE_GRAINSIZE_EXPR (clause),
spc, flags, false);
pp_right_paren (pp);
@ -1073,6 +1075,8 @@ dump_omp_clause (pretty_printer *pp, tree clause, int spc, dump_flags_t flags)
case OMP_CLAUSE_NUM_TASKS:
pp_string (pp, "num_tasks(");
if (OMP_CLAUSE_NUM_TASKS_STRICT (clause))
pp_string (pp, "strict:");
dump_generic_node (pp, OMP_CLAUSE_NUM_TASKS_EXPR (clause),
spc, flags, false);
pp_right_paren (pp);

5
gcc/tree.h
View file

@ -1612,6 +1612,11 @@ class auto_suppress_location_wrappers
#define OMP_CLAUSE_PRIORITY_EXPR(NODE) \
OMP_CLAUSE_OPERAND (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_PRIORITY),0)
#define OMP_CLAUSE_GRAINSIZE_STRICT(NODE) \
TREE_PRIVATE (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_GRAINSIZE))
#define OMP_CLAUSE_NUM_TASKS_STRICT(NODE) \
TREE_PRIVATE (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_NUM_TASKS))
/* OpenACC clause expressions */
#define OMP_CLAUSE_EXPR(NODE, CLAUSE) \
OMP_CLAUSE_OPERAND (OMP_CLAUSE_SUBCODE_CHECK (NODE, CLAUSE), 0)

1
include/gomp-constants.h
View file

@ -222,6 +222,7 @@ enum gomp_map_kind
#define GOMP_TASK_FLAG_NOGROUP (1 << 11)
#define GOMP_TASK_FLAG_REDUCTION (1 << 12)
#define GOMP_TASK_FLAG_DETACH (1 << 13)
#define GOMP_TASK_FLAG_STRICT (1 << 14)
/* GOMP_target{_ext,update_ext,enter_exit_data} flags argument. */
#define GOMP_TARGET_FLAG_NOWAIT (1 << 0)

27
libgomp/taskloop.c
View file

@ -97,6 +97,7 @@ GOMP_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
#endif
TYPE task_step = step;
TYPE nfirst_task_step = step;
unsigned long nfirst = n;
if (flags & GOMP_TASK_FLAG_GRAINSIZE)
{
@ -109,7 +110,22 @@ GOMP_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
if (num_tasks != ndiv)
num_tasks = ~0UL;
#endif
if (num_tasks <= 1)
if ((flags & GOMP_TASK_FLAG_STRICT)
&& num_tasks != ~0ULL)
{
UTYPE mod = n % grainsize;
task_step = (TYPE) grainsize * step;
if (mod)
{
num_tasks++;
nfirst_task_step = (TYPE) mod * step;
if (num_tasks == 1)
task_step = nfirst_task_step;
else
nfirst = num_tasks - 2;
}
}
else if (num_tasks <= 1)
{
num_tasks = 1;
task_step = end - start;
@ -124,6 +140,7 @@ GOMP_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
task_step = (TYPE) grainsize * step;
if (mul != n)
{
nfirst_task_step = task_step;
task_step += step;
nfirst = n - mul - 1;
}
@ -135,6 +152,7 @@ GOMP_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
task_step = (TYPE) div * step;
if (mod)
{
nfirst_task_step = task_step;
task_step += step;
nfirst = mod - 1;
}
@ -153,6 +171,7 @@ GOMP_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
task_step = (TYPE) div * step;
if (mod)
{
nfirst_task_step = task_step;
task_step += step;
nfirst = mod - 1;
}
@ -225,7 +244,7 @@ GOMP_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
start += task_step;
((TYPE *)arg)[1] = start;
if (i == nfirst)
task_step -= step;
task_step = nfirst_task_step;
fn (arg);
arg += arg_size;
if (!priority_queue_empty_p (&task[i].children_queue,
@ -258,7 +277,7 @@ GOMP_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
start += task_step;
((TYPE *)data)[1] = start;
if (i == nfirst)
task_step -= step;
task_step = nfirst_task_step;
fn (data);
if (!priority_queue_empty_p (&task.children_queue,
MEMMODEL_RELAXED))
@ -303,7 +322,7 @@ GOMP_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
start += task_step;
((TYPE *)arg)[1] = start;
if (i == nfirst)
task_step -= step;
task_step = nfirst_task_step;
thr->task = parent;
task->kind = GOMP_TASK_WAITING;
task->fn = fn;

3
libgomp/testsuite/libgomp.c-c++-common/taskloop-4.c
View file

@ -85,7 +85,8 @@ main ()
if (test (7, 21, 2, 15, grainsize, &ntasks, &min_iters, &max_iters) != 7
|| ntasks != 1 || min_iters != 7 || max_iters != 7)
__builtin_abort ();
/* If num_tasks is present, # of task loop iters is min (# of loop iters, num_tasks). */
/* If num_tasks is present, # of tasks is min (# of loop iters, num_tasks)
and each task has at least one iteration. */
if (test (-51, 2500, 48, 9, num_tasks, &ntasks, &min_iters, &max_iters) != 54
|| ntasks != 9)
__builtin_abort ();

135
libgomp/testsuite/libgomp.c-c++-common/taskloop-5.c Normal file
View file

@ -0,0 +1,135 @@
/* { dg-do run } */
/* { dg-options "-O2" } */
int u[64], v, w[64];
__attribute__((noinline, noclone)) int
test (int a, int b, int c, int d, void (*fn) (int, int, int, int),
int *num_tasks, int *min_iters, int *max_iters, int *sep)
{
int i, j, t = 0;
__builtin_memset (u, 0, sizeof u);
v = 0;
fn (a, b, c, d);
*min_iters = 0;
*max_iters = 0;
*num_tasks = v;
*sep = v;
if (v)
{
*min_iters = u[0];
*max_iters = u[0];
t = u[0];
for (i = 1; i < v; i++)
{
if (*min_iters > u[i])
*min_iters = u[i];
if (*max_iters < u[i])
*max_iters = u[i];
t += u[i];
}
if (*min_iters != *max_iters)
{
for (i = 0; i < v - 1; i++)
{
int min_idx = i;
for (j = i + 1; j < v; j++)
if (w[min_idx] > w[j])
min_idx = j;
if (min_idx != i)
{
int tem = u[i];
u[i] = u[min_idx];
u[min_idx] = tem;
tem = w[i];
w[i] = w[min_idx];
w[min_idx] = tem;
}
}
if (u[0] != *max_iters)
__builtin_abort ();
for (i = 1; i < v; i++)
if (u[i] != u[i - 1])
{
if (*sep != v || u[i] != *min_iters)
__builtin_abort ();
*sep = i;
}
}
}
return t;
}
void
grainsize (int a, int b, int c, int d)
{
int i, j = 0, k = 0;
#pragma omp taskloop firstprivate (j, k) grainsize(strict:d)
for (i = a; i < b; i += c)
{
if (j == 0)
{
#pragma omp atomic capture
k = v++;
if (k >= 64)
__builtin_abort ();
w[k] = i;
}
u[k] = ++j;
}
}
void
num_tasks (int a, int b, int c, int d)
{
int i, j = 0, k = 0;
#pragma omp taskloop firstprivate (j, k) num_tasks(strict:d)
for (i = a; i < b; i += c)
{
if (j == 0)
{
#pragma omp atomic capture
k = v++;
if (k >= 64)
__builtin_abort ();
w[k] = i;
}
u[k] = ++j;
}
}
int
main ()
{
#pragma omp parallel
#pragma omp single
{
int min_iters, max_iters, ntasks, sep;
/* If grainsize is present and has strict modifier, # of task loop iters is == grainsize,
except that it can be smaller on the last task. */
if (test (0, 79, 1, 17, grainsize, &ntasks, &min_iters, &max_iters, &sep) != 79
|| ntasks != 5 || min_iters != 11 || max_iters != 17 || sep != 4)
__builtin_abort ();
if (test (-49, 2541, 7, 28, grainsize, &ntasks, &min_iters, &max_iters, &sep) != 370
|| ntasks != 14 || min_iters != 6 || max_iters != 28 || sep != 13)
__builtin_abort ();
if (test (7, 21, 2, 15, grainsize, &ntasks, &min_iters, &max_iters, &sep) != 7
|| ntasks != 1 || min_iters != 7 || max_iters != 7 || sep != 1)
__builtin_abort ();
/* If num_tasks is present, # of tasks is min (# of loop iters, num_tasks)
and each task has at least one iteration. If strict modifier is present,
first set of tasks has ceil (# of loop iters / num_tasks) iterations,
followed by possibly empty set of tasks with floor (# of loop iters / num_tasks)
iterations. */
if (test (-51, 2500, 48, 9, num_tasks, &ntasks, &min_iters, &max_iters, &sep) != 54
|| ntasks != 9 || min_iters != 6 || max_iters != 6 || sep != 9)
__builtin_abort ();
if (test (0, 57, 1, 9, num_tasks, &ntasks, &min_iters, &max_iters, &sep) != 57
|| ntasks != 9 || min_iters != 6 || max_iters != 7 || sep != 3)
__builtin_abort ();
if (test (0, 25, 2, 17, num_tasks, &ntasks, &min_iters, &max_iters, &sep) != 13
|| ntasks != 13 || min_iters != 1 || max_iters != 1 || sep != 13)
__builtin_abort ();
}
return 0;
}