This makes sure that we don't introduce strange cases where we have
nodes outside the query system that could break red/green tracking
and it will allow to keep red/green neatly encapsulated within the
DepGraph implementation.
incr.comp.: Cache Hir-DepNodeIndices in the HIR map.
In preparation for red/green. This should also be faster than before without any additional memory cost.
r? @nikomatsakis
A task function is now given as a `fn` pointer to ensure that it carries
no state. Each fn can take two arguments, because that worked out to be
convenient -- these two arguments must be of some type that is
`DepGraphSafe`, a new trait that is intended to prevent "leaking"
information into the task that was derived from tracked state.
This intentionally leaves `DepGraph::in_task()`, the more common form,
alone. Eventually all uses of `DepGraph::in_task()` should be ported
to `with_task()`, but I wanted to start with a smaller subset.
Originally I wanted to use closures bound by an auto trait, but that
approach has some limitations:
- the trait cannot have a `read()` method; since the current method
is unused, that may not be a problem.
- more importantly, we would want the auto trait to be "undefined" for all types
*by default* -- that is, this use case doesn't really fit the typical
auto trait scenario. For example, imagine that there is a `u32` loaded
out of a `hir::Node` -- we don't really want to be passing that
`u32` into the task!
This commit guards all calls to `DepGraphThreadData::enqueue` with a
check to make sure it is enabled. This requires distinguishing between a
"fully enabled" and an "enqueue-enabled" graph.
This change avoids some useless allocation and vector manipulations when
the graph is disabled (i.e. when incremental compilation is off) which
improves speed by ~1% on some of the rustc-benchmarks.
It is useful to track down an errant edge that is being added. This is
not a perfect mechanism, since it doesn't consider (e.g.) if we are
in an ignored task, but it's helpful enough for now.
In the older version, a `.o` and ` .bc` file were separate
work-products. This newer version keeps, for each codegen-unit, a set
of files of different kinds. We assume that if any kinds are available
then all the kinds we need are available, since the precise set of
switches will depend on attributes and command-line switches.
Should probably test this: the effect of changing attributes in
particular might not be successfully tracked?
A work product right now is just a `.o` file. In the future it probably
includes other kinds of files, such as `.bc` files saving the
unoptimized LLVM IR.
However, because WorkProductIds must be independent of DefIds, so that
they don't need translation, this system may not be suitable *as is* for
storing fine-grained information (such as the MIR for individual defs),
as it was originally intended. We will want to refactor some for that.
