On 17.10.23 15:34, Jakub Jelinek wrote:
On Tue, Oct 17, 2023 at 03:12:46PM +0200, Tobias Burnus wrote:
C++11 (and C23) attribute do not seem to be properly handled:
[[omp::decl (declare target,indirect(1))]]
int foo(void) { return 5; }
[[omp::decl (declare target indirect)]]
int bar(void) { return 8; }
Isn't that correct?
No it isn't. Following your argument below, the following is violated:
"If the directive has a clause, it must contain at least one enter
clause, link clause, or local clause."
(OpenMP before 5.2 had 'to' instead of 'enter' and 5.2 had 'enter' with
'to' as alias.)
And the clause above does not have those. Alternatively permitted is:
"If the extended-list argument is specified, no clauses may be specified."
But that cannot be the case as the "indirect" clause has been specified.
* * *
Declare target directive has the forms
declare target (list)
declare target
declare target clauses
The first form is essentially equivalent to declare target enter (list),
the second to begin declare target with no clauses.
Now,
[[omp::decl (declare target)]] int v;
matches the first form and so enter (v) clause is implied.
But say
[[omp::decl (declare target, device_type (any))]] int v;
is the third type and so nothing is implied, so it is equivalent to
int v;
I have to admit that I failed to read 'omp::decl()' in the spec before
trying it. The TR11 spec states:
"A declarative directive that is declaration-associated may
alternatively be expressed as an attribute specifier where
directive-attr is dec( directive-specification
"A declarative directive with an association of none that accepts a
variable list or extended list as a directive argument or clause
argument may alternatively be expressed with an attribute specifier that
also uses thedeclattribute, applies to variable and/or function
declarations, and omits the variable list or extended list argument. The
effect is as if the omitted list argument is the list of declared
variables and/or functions to which the attribute specifier applies."
('declare target' is a bit odd as it either accept a variable list or
supports a form where a clause accepts a variable list, which is confusing.)
#pragma omp declare target device_type (any)
Don't remember if that is supposed to be an error or just not do anything
because there is no enter or to or link clause.
That's invalid per the restriction above - well, except for the
delimited form, which permits 'indirect' and 'device_type' as only
clauses. But that does not apply here as the association with
'omp::decl' must be none (i.e. 'delimited' is not permitted).
So, I think if you want to make foo indirect, the above would have to be:
[[omp::decl (declare target,enter,indirect(1))]]
int foo(void) { return 5; }
I concur - and admit that I missed the 'enter'.
Still, there is an issue as the restriction is not checked for.
Same with:
#pragma omp declare target indirect
(invalid but accepted) while
#pragma omp declare target device_type(any) indirect
fails with: "error: directive with only ‘device_type’ clause". The error
due to 'device_type' is no longer completely correct as I would count
'indirect' as another directive.
Tobias
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