Adds an optional filtering control function to the dataflow solver's
initializeAndRun callback, which controls which analyses will be
initialized when running the solver. This makes it possible to reuse
existing dataflow solver instances that have already run to a fixpoint
without re-initializing all of the analyses that have already converged.
A new analysis and test pass is also added, which illustrates how the
filtering can be useful to run a staged analysis, which would not have
been possible before. The example analysis, called `BarAnalysis`,
depends on the converged state of the `FooAnalysis`. The Bar analysis is
a forward analysis that tracks, for each program point, whether any of
the preceding program points hold a `foo_state` that is divisible by 4.
In the example test, the control flow graph looks like the following:
```
entry-block
/ \
bb0 bb2
\ /
bb1
```
The `foo_state` of `bb1` depends on the `foo_state` of `bb0` and `bb2`.
If the solver goes through `bb0->bb1` before `bb2->bb1`, then there is
an intermediate stage in the analyses where the state of `bb1` could be
divisible by 4, even though the final state of `bb1` will not be
divisible by 4 in the converged state. If the `BarAnalysis` runs on
`bb1` in this intermediate state, then it will get stuck with the
"divisible by 4" state, and the analysis will not yield the desired
results.
This PR ensures that the `BarAnalysis` will see the correct state
`foo_state`, because the `FooAnalysis` will fully run to a fixpoint
before the `BarAnalysis` is loaded, initialized, and run.
The Foo and Bar analyses are just trivial examples, but this pattern is
useful when there are analyses that can be made more effective by using
complementary analyses like integer range/divisibility analyses.
**Note for integration:**
DataFlowSolver::load now stores the concrete analysis TypeID, exposed
via DataFlowAnalysis::getTypeID(). Downstream DataFlowAnalysis
subclasses defined in anonymous namespaces must add
MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(ClassName) to their class
body.
Assisted-by: Codex (gpt-5.4)
d4ba0194f5