Previously, most of the benchmarks just measured time spent reading or
writing the array on the device. The transfer only happened on the first
iteration and was then cached on the device.
This change clears out the array every iteration so that the array has
to be transferred afresh.
5f541d251 Drop log message when ignoring copy in move
4c56797c5 Remove ArrayHandleSOA constructors with ambiguous move semantics
0d484505e Fix bad gcc compiler warning about static definition (again)
216307744 Fix errors with memory access
e23989bde Use data method to get pointer from std::vector
2e243cbba Fix issue with using std::string in ArrayHandle
46f253b92 Fix compiler issue with MSVC
d1a4aecc5 Improvements to moving data into ArrayHandle
Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Robert Maynard <robert.maynard@kitware.com>
Acked-by: Allison Vacanti <alliepiper16@gmail.com>
Merge-request: !2184
For `make_ArrayHandle` and `make_Field` when it is determined that the
data can be safely moved, just silently move instead of copy instead of
printing a log message saying the copy flag will be ignored.
Also fix an issue with `make_ArrayHandle` when the data was not moved
when it could have been.
The recent version of ArrayHandleBasic allocates typeless arrays without
any initialization. This can cause issues with types that require a
constructor. The UnitTestVariantArrayHandle was trying to create an
ArrayHandle with an std::string, and the uninitialized strings were
causing crashes on some platforms.
We have made several improvements to adding data into an `ArrayHandle`.
## Moving data from an `std::vector`
For numerous reasons, it is convenient to define data in a `std::vector`
and then wrap that into an `ArrayHandle`. It is often the case that an
`std::vector` is filled and then becomes unused once it is converted to an
`ArrayHandle`. In this case, what we really want is to pass the data off to
the `ArrayHandle` so that the `ArrayHandle` is now managing the data and
not the `std::vector`.
C++11 has a mechanism to do this: move semantics. You can now pass
variables to functions as an "rvalue" (right-hand value). When something is
passed as an rvalue, it can pull state out of that variable and move it
somewhere else. `std::vector` implements this movement so that an rvalue
can be moved to another `std::vector` without actually copying the data.
`make_ArrayHandle` now also takes advantage of this feature to move rvalue
`std::vector`s.
There is a special form of `make_ArrayHandle` named `make_ArrayHandleMove`
that takes an rvalue. There is also a special overload of
`make_ArrayHandle` itself that handles an rvalue `vector`. (However, using
the explicit move version is better if you want to make sure the data is
actually moved.)
## Make `ArrayHandle` from initalizer list
A common use case for using `std::vector` (particularly in our unit tests)
is to quickly add an initalizer list into an `ArrayHandle`. Now you can
by simply passing an initializer list to `make_ArrayHandle`.
## Deprecated `make_ArrayHandle` with default shallow copy
For historical reasons, passing an `std::vector` or a pointer to
`make_ArrayHandle` does a shallow copy (i.e. `CopyFlag` defaults to `Off`).
Although more efficient, this mode is inherintly unsafe, and making it the
default is asking for trouble.
To combat this, calling `make_ArrayHandle` without a copy flag is
deprecated. In this way, if you wish to do the faster but more unsafe
creation of an `ArrayHandle` you should explicitly express that.
This requried quite a few changes through the VTK-m source (particularly in
the tests).
## Similar changes to `Field`
`vtkm::cont::Field` has a `make_Field` helper function that is similar to
`make_ArrayHandle`. It also features the ability to create fields from
`std::vector`s and C arrays. It also likewise had the same unsafe behavior
by default of not copying from the source of the arrays.
That behavior has similarly been depreciated. You now have to specify a
copy flag.
The ability to construct a `Field` from an initializer list of values has
also been added.
