Ensure :VAR_MAP and :FUNC_MAP are output in order

[tob2]

Before, only if there is an '.extern', is_decl is set and only
then the variable/function is added to 'decls'. However, global
variables/functions may not have .extern - even if they show up
with :VAR_MAP and :FUNC_MAP. GCC's mkoffload uses the latter and
requires that the order matches the original order.

As the output is done as:

	write_stmts (out, rev_stmts (decls));
	htab_traverse (symbol_table, traverse, (void *)out);
	write_stmts (out, rev_stmts (fns));

it might have happen that :VAR_MAP/:FUNC_MAP lines will be output
in hash-map order, which can cause the wrong order.

https://gcc.gnu.org/PR100059

• nvptx-as.c (parse_file): Set is_decl when there is a :VAR_MAP or :FUNC_MAP.

[tob2]

Testcase is:

int i = 0, a[3];

void update () { 
  i = 5; a[0] = 42; a[1] = 43; a[2] = 44;
}

#pragma omp declare target link(i,a)
#pragma omp declare target to(update)  

int main () {
  #pragma omp target map(from: i, a)
    update();
__builtin_printf("%d, %d, %d, %d\n", i,a[0],a[1],a[2]);
  return 0;
}

• With the patch (or host compilation or GCN compilation), we get: 5, 42, 43, 44
• Without the patch, we get: 42, 5, 0, 0

By inserting comment outputs before the write_stmts/htab_traverse it shows that both :VAR_MAP and :FUNC_MAP are output during the traverse!

Once this patch is in, the longer example at https://gcc.gnu.org/bugzilla/attachment.cgi?id=50578 (https://gcc.gnu.org/PR100059) should be committed to GCC.

Side question: Why did it not show up before?

[vries]

Testcase is:

int i = 0, a[3];

void update () { 
  i = 5; a[0] = 42; a[1] = 43; a[2] = 44;
}

#pragma omp declare target link(i,a)
#pragma omp declare target to(update)  

int main () {
  #pragma omp target map(from: i, a)
    update();
__builtin_printf("%d, %d, %d, %d\n", i,a[0],a[1],a[2]);
  return 0;
}

* **With the patch** (or host compilation or GCN compilation), we get: `5, 42, 43, 44`

* **Without the patch**, we get: `42, 5, 0, 0`

Reproduced both the without and with patch behaviour.

[vries]

Thomas, ping.

[tob2]

Another example for this is https://github.com/clang-ykt/omptests 's t-same-name-definitions which has the same issue + is fixed by the pull request.

[tob2]

@tschwinge — Ping²

[vries]

@tschwinge — Ping^3

[tschwinge]

Note commit 3f67564 "Ensure :VAR_MAP and :FUNC_MAP are output in order: add more test cases [#29]".

[tschwinge]

Note commit 3f67564 "Ensure :VAR_MAP and :FUNC_MAP are output in order: add more test cases [#29]".

..., which is now resolved via commit aa3404a "Ensure :VAR_MAP and :FUNC_MAP are output in order, part II [#29]".