IncIDFA: An Efficient and Generic Algorithm for Incremental Iterative Dataflow Analysis
Bibliographic record
Abstract
Iterative dataflow analyses (IDFAs) are important static analyses employed by tools like compilers for enabling program optimizations, comprehension, verification, and more. During compilation of a program, optimizations/transformations can render existing dataflow solutions stale, jeopardizing the optimality and correctness of subsequent compiler passes. Exhaustively recomputing these solutions can be costly. Since most program changes impact only small portions of the flowgraph, several incrementalization approaches have been proposed for various subclasses of IDFAs. However, these approaches face one or more of these limitations: (i) loss of precision compared to exhaustive analysis, (ii) inability to handle arbitrary lattices and dataflow functions, and (iii) lacking fully automated incrementalization of the IDFA. As a result, mainstream compilers lack frameworks for generating precise incremental versions of arbitrary IDFAs, leaving analysis writers to create ad hoc algorithms for incrementalization – an often cumbersome and error-prone task. To tackle these challenges, we introduce IncIDFA , a novel algorithm that delivers precise and efficient incremental variants of any monotone IDFA. IncIDFA utilizes a two-pass approach to maintain precision. Unlike prior works, IncIDFA avoids resetting the dataflow solutions to least informative values when dealing with strongly-connected regions and arbitrary program changes. We formally prove the precision guarantees of IncIDFA for arbitrary dataflow problems and program changes. IncIDFA has been implemented in the IMOP compiler framework for parallel OpenMP C programs. To showcase its generality, we have instantiated IncIDFA to ten specific dataflow analyses, without requiring any additional code for incrementalization. We present an evaluation of IncIDFA on a real-world set of optimization passes, across two different architectures. As compared to exhaustive recomputation, IncIDFA resulted in a speedup of up to 11× (geomean 2.6×) in incremental-update time, and improvement of up to 46% (geomean 15.1%) in the total compilation time.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.008 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.003 | 0.005 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.009 | 0.005 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".