Number of components in a mesh tag is more than INT8_MAX

[zhangchonglin]

Copying the same issue from XGCm for better location.

When the number of components for a mesh tag exceeds INT8_MAX, which is 127, it is problematic as this could often happen.

Simply inferring from the below assert (OMEGA_H_CHECK) statement, INT8_MAX seems to be the upper limit manually set currently for the number of components. From my understanding, it may not be a simple manual limit to change, and could be related to many other operations:

omega_h/src/Omega_h_mesh.cpp

Lines 242 to 267 in b4a92ca

	template <typename T>
	void Mesh::add_tag(Int ent_dim, std::string const& name, Int ncomps,
	Read<T> array, bool internal) {
	check_dim2(ent_dim);
	auto it = tag_iter(ent_dim, name);
	auto had_tag = (it != tags_[ent_dim].end());
	Tag<T>* tag;
	if (had_tag) {
	tag = as<T>(it->get());
	OMEGA_H_CHECK(ncomps == tag->ncomps());
	} else {
	check_tag_name(name);
	OMEGA_H_CHECK(ncomps >= 0);
	OMEGA_H_CHECK(ncomps <= Int(INT8_MAX));
	OMEGA_H_CHECK(tags_[ent_dim].size() < size_t(INT8_MAX));
	tag = new Tag<T>(name, ncomps);
	TagPtr ptr(tag);
	tags_[ent_dim].push_back(std::move(ptr));
	}
	/* internal typically indicates migration/adaptation/file reading,
	when we do not want any invalidation to take place.
	the invalidation is there to prevent users changing coordinates
	etc. without updating dependent fields */
	if (!internal) react_to_set_tag(ent_dim, name);
	tag->set_array(array);
	}

[jacobmerson]

@zhangchonglin is this still a problem for you?

[zhangchonglin]

I think we can close this as long as we are not using more than 127 components for a mesh tag.

[jacobmerson]

There are checks in place so Omega_h should crash if you use more than INT8 max. The question is more for you...do you still need more than 127 tags in XGCm?

[zhangchonglin]

I think we are fine for now as this is mostly a visualization issue.

[zhangchonglin]

This is fine for XGCm for now.