The core implementation of the dataflow anlysis framework is
interpocedural by design. While this offers better analysis precision,
it also comes with additional cost as it takes longer for the analysis
to reach the fixpoint state. Add a configuration mechanism to the
dataflow solver to control whether it operates inteprocedurally or not
to offer clients a choice.
As a positive side effect, this change also adds hooks for explicitly
processing external/opaque function calls in the dataflow analyses,
e.g., based off of attributes present in the the function declaration or
call operation such as alias scopes and modref available in the LLVM
dialect.
This change should not affect existing analyses and the default solver
configuration remains interprocedural.
Co-authored-by: Jacob Peng <jacobmpeng@gmail.com>
Currently, data in `AbstractSparseBackwardDataFlowAnalysis` is
considered to flow one-to-one, in order, from the operands of an op
implementing `CallOpInterface` to the arguments of the function it is
calling.
This understanding of the data flow is inaccurate. The operands of such
an op that forward to the function arguments are obtained using a
method provided by `CallOpInterface` called `getArgOperands()`.
This commit fixes this bug by using `getArgOperands()` instead of
`getOperands()` to get the mapping from operands to function arguments
because not all operands necessarily forward to the function arguments
and even if they do, they don't necessarily have to be in the order in
which they appear in the op. The operands that don't get forwarded are
handled by the newly introduced `visitCallOperand()` function, which
works analogous to the `visitBranchOperand()` function.
This fix is also propagated to liveness analysis that earlier relied on
this incorrect implementation of the sparse backward dataflow analysis
framework and corrects some incorrect assumptions made in it.
Extra cleanup: Improved a comment and removed an unnecessary code line.
Signed-off-by: Srishti Srivastava <srishtisrivastava.ai@gmail.com>
Reviewed By: matthiaskramm, jcai19
Differential Revision: https://reviews.llvm.org/D157261
