Re-land PR after being reverted because of buildbot failures.
This patch adds representation for `device_type` clause information on
compute construct (parallel, kernels, serial).
The `device_type` clause on compute construct impacts clauses that
appear after it. The values impacted by `device_type` are now tied with
an attribute array that represent the device_type associated with them.
`DeviceType::None` is used to represent the value produced by a clause
before any `device_type`. The operands and the attribute information are
parser/printed together.
This is an example with `vector_length` clause. The first value (64) is
not impacted by `device_type` so it will be represented with
DeviceType::None. None is not printed. The second value (128) is tied
with the `device_type(multicore)` clause.
```
!$acc parallel vector_length(64) device_type(multicore) vector_length(256)
```
```
acc.parallel vector_length(%c64 : i32, %c128 : i32 [#acc.device_type<multicore>]) {
}
```
When multiple values can be produced for a single clause like
`num_gangs` and `wait`, an extra attribute describe the number of values
belonging to each `device_type`. Values and attributes are
parsed/printed together.
```
acc.parallel num_gangs({%c2 : i32, %c4 : i32}, {%c4 : i32} [#acc.device_type<nvidia>])
```
While preparing this patch I noticed that the wait devnum is not part of
the operations and is not lowered. It will be added in a follow up
patch.
a25da1a921