Wed 15 Jun 2022 11:40 - 12:00 at Macaw - Program Analysis Chair(s): Qirun Zhang

Pointer analysis is one of the fundamental problems in static program analysis. Given a set of pointers, the task is to produce a useful over-approximation of the memory locations that each pointer may point-to at runtime. The most common formulation is Andersen’s Pointer Analysis (APA), defined as an inclusion-based set of $m$ pointer constraints over a set of $n$ pointers. Scalability is extremely important, as points-to information is a prerequisite to many other components in the static-analysis pipeline. Existing algorithms solve APA in $O(n^2\cdot m)$ time, while it has been conjectured that the problem has no truly sub-cubic algorithm, with a proof so far having remained elusive. It is also well-known that APA can be solved in $O(n^2)$ time under certain sparsity conditions that hold naturally in some settings. Besides these simple bounds, the complexity of the problem has remained poorly understood.

In this work we draw a rich fine-grained and paralellel complexity landscape of APA, and present upper and lower bounds. First, we establish an $O(n^3)$ upper-bound for general APA, improving over $O(n^2\cdot m)$ as $n=O(m)$. Second, we show that even \emph{on-demand} APA (may a \emph{specific} pointer $a$ point to a \emph{specific} location $b$?'') has an $\Omega(n^3)$ (combinatorial) lower bound under standard complexity-theoretic hypotheses. This formally establishes the long-conjecturedcubic bottleneck'' of APA, and shows that our $O(n^3)$-time algorithm is optimal. Third, we show that under mild restrictions, APA is solvable in $\tilde{O}(n^{\omega})$ time, where $\omega<2.373$ is the matrix-multiplication coefficient. It is believed that $\omega=2+o(1)$, in which case this bound becomes quadratic. Fourth, we show that even under such restrictions, even the \emph{on-demand} problem has an $\Omega(n^2)$ lower bound under standard complexity-theoretic hypotheses, and hence our algorithm is optimal when $\omega=2+o(1)$. Fifth, we study the parallelizability of APA and establish lower and upper bounds: (i) in general, the problem is P-complete and hence not parallelizable, whereas (ii) under mild restrictions, the problem is in NC and hence parallelizable. Our theoretical treatment formalizes several insights that can lead to practical improvements in the future.

Wed 15 Jun

Displayed time zone: Pacific Time (US & Canada) change

10:40 - 12:00
Program AnalysisSIGPLAN Track at Macaw
Chair(s): Qirun Zhang Georgia Institute of Technology, USA
10:40
20m
Talk
(OOPSLA 2020) Perfectly Parallel Fairness Certification of Neural Networks
SIGPLAN Track
Caterina Urban Inria & École Normale Supérieure | Université PSL, Maria Christakis MPI-SWS, Valentin Wüstholz ConsenSys, Fuyuan Zhang MPI-SWS
11:00
20m
Talk
(PLDI 2020) OOElala : Order-Of-Evaluation based Alias Analysis for compiler optimization
SIGPLAN Track
Ankush Phulia IIT Delhi, India, Vaibhav Bhagee IIT Delhi, India, Sorav Bansal IIT Delhi and CompilerAI Labs
11:20
20m
Talk
(POPL 2021) Simplifying Dependent Reductions with the Polyhedral Model
SIGPLAN Track
Cambridge Yang MIT CSAIL, Eric Atkinson MIT CSAIL, Michael Carbin Massachusetts Institute of Technology
11:40
20m
Talk
(POPL 2021) The Fine-Grained and Parallel Complexity of Andersen's Pointer Analysis
SIGPLAN Track
Andreas Pavlogiannis Aarhus University, Anders Alnor Mathiasen Aarhus University