4 Commits

Author SHA1 Message Date
Eric Li
45643cfcc1 [clang][dataflow] Centralize expression skipping logic
A follow-up to 62b2a47 to centralize the logic that skips expressions
that the CFG does not emit. This allows client code to avoid
sprinkling this logic everywhere.

Add redirects in the transfer function to similarly skip such
expressions by forwarding the visit to the sub-expression.

Differential Revision: https://reviews.llvm.org/D124965
2022-05-05 20:28:11 +00:00
Eric Li
58abe36ae7 [clang][dataflow] Add flowConditionIsTautology function
Provide a way for users to check if a flow condition is
unconditionally true.

Differential Revision: https://reviews.llvm.org/D124943
2022-05-05 03:57:43 +00:00
Stanislav Gatev
955a05a278 [clang][dataflow] Optimize flow condition representation
Enable efficient implementation of context-aware joining of distinct
boolean values. It can be used to join distinct boolean values while
preserving flow condition information.

Flow conditions are represented as Token <=> Clause iff formulas. To
perform context-aware joining, one can simply add the tokens of flow
conditions to the formula when joining distinct boolean values, e.g:
`makeOr(makeAnd(FC1, Val1), makeAnd(FC2, Val2))`. This significantly
simplifies the implementation of `Environment::join`.

This patch removes the `DataflowAnalysisContext::getSolver` method.
The `DataflowAnalysisContext::flowConditionImplies` method should be
used instead.

Reviewed-by: ymandel, xazax.hun

Differential Revision: https://reviews.llvm.org/D124395
2022-05-01 16:25:29 +00:00
Stanislav Gatev
ae60884dfe [clang][dataflow] Add flow condition constraints to Environment
This is part of the implementation of the dataflow analysis framework.
See "[RFC] A dataflow analysis framework for Clang AST" on cfe-dev.

Reviewed-by: ymandel, xazax.hun

Differential Revision: https://reviews.llvm.org/D120711
2022-03-02 08:57:27 +00:00