Cliff Click

Bio: Cliff Click is an academic researcher from Rice University. The author has contributed to research in topics: Program optimization & Partial redundancy elimination. The author has an hindex of 2, co-authored 2 publications receiving 189 citations.

Combining analyses, combining optimizations

Abstract: Modern optimizing compilers use several passes over a program's intermediate representation to generate good code. Many of these optimizations exhibit a phase-ordering problem. Getting the best code may require iterating optimizations until a fixed point is reached. Combining these phases can lead to the discovery of more facts about the program, exposing more opportunities for optimization. This article presents a framework for describing optimizations. It shows how to combine two such frameworks and how to reason about the properties of the resulting framework. The structure of the frame work provides insight into when a combination yields better results. To make the ideas more concrete, this article presents a framework for combining constant propagation, value numbering, and unreachable-code elimination. It is an open question as to what other frameworks can be combined in this way.

The Truth, The Whole Truth, and Nothing But the Truth: A Pragmatic Guide to Assessing Empirical Evaluations

Abstract: An unsound claim can misdirect a field, encouraging the pursuit of unworthy ideas and the abandonment of promising ideas. An inadequate description of a claim can make it difficult to reason about the claim, for example, to determine whether the claim is sound. Many practitioners will acknowledge the threat of unsound claims or inadequate descriptions of claims to their field. We believe that this situation is exacerbated, and even encouraged, by the lack of a systematic approach to exploring, exposing, and addressing the source of unsound claims and poor exposition.This article proposes a framework that identifies three sins of reasoning that lead to unsound claims and two sins of exposition that lead to poorly described claims and evaluations. Sins of exposition obfuscate the objective of determining whether or not a claim is sound, while sins of reasoning lead directly to unsound claims.Our framework provides practitioners with a principled way of critiquing the integrity of their own work and the work of others. We hope that this will help individuals conduct better science and encourage a cultural shift in our research community to identify and promulgate sound claims.

The java hotspot TM server compiler

Abstract: The Java HotSpotTM Server Compiler achieves improved asymptotic performance through a combination of object-oriented and classical-compiler optimizations. Aggressive inlining using class-hierarchy analysis reduces function call overhead and provides opportunities for many compiler optimizations.

Fast, effective dynamic compilation

Abstract: Dynamic compilation enables optimization based on the values of invariant data computed at run-time. Using the values of these run-time constants, a dynamic compiler can eliminate their memory loads, perform constant propagation and folding, remove branches they determine, and fully unroll loops they bound. However, the performance benefits of the more efficient, dynamically-compiled code are offset by the run-time cost of the dynamic compile. Our approach to dynamic compilation strives for both fast dynamic compilation and high-quality dynamically-compiled code: the programmer annotates regions of the programs that should be compiled dynamically; a static, optimizing compiler automatically produces pre-optimized machine-code templates, using a pair of dataflow analyses that identify which variables will be constant at run-time; and a simple, dynamic compiler copies the templates, patching in the computed values of the run-time constants, to produce optimized, executable code. Our work targets general- purpose, imperative programming languages, initially C. Initial experiments applying dynamic compilation to C programs have produced speedups ranging from 1.2 to 1.8.

MLIR: scaling compiler infrastructure for domain specific computation

Abstract: This work presents MLIR, a novel approach to building reusable and extensible compiler infrastructure. MLIR addresses software fragmentation, compilation for heterogeneous hardware, significantly reducing the cost of building domain specific compilers, and connecting existing compilers together. MLIR facilitates the design and implementation of code generators, translators and optimizers at different levels of abstraction and across application domains, hardware targets and execution environments. The contribution of this work includes (1) discussion of MLIR as a research artifact, built for extension and evolution, while identifying the challenges and opportunities posed by this novel design, semantics, optimization specification, system, and engineering. (2) evaluation of MLIR as a generalized infrastructure that reduces the cost of building compilers---describing diverse use-cases to show research and educational opportunities for future programming languages, compilers, execution environments, and computer architecture. The paper also presents the rationale for MLIR, its original design principles, structures and semantics.

Global code motion/global value numbering

Abstract: We believe that optimizing compilers should treat the machine-independent optimizations (e.g., conditional constant propagation, global value numbering) and code motion issues separately.’ Removing the code motion requirements from the machine-independent optimization allows stronger optimizations using simpler algorithms. Preserving a legal schedule is one of the prime sources of complexity in algorithms like PRE [18, 13] or global congruence finding [2, 20].

Vortex: an optimizing compiler for object-oriented languages

Abstract: Previously, techniques such as class hierarchy analysis and profile-guided receiver class prediction have been demonstrated to greatly improve the performance of applications written in pure object-oriented languages, but the degree to which these results are transferable to applications written in hybrid languages has been unclear. In part to answer this question, we have developed the Vortex compiler infrastructure, a language-independent optimizing compiler for object-oriented languages, with front-ends for Cecil, C++, Java, and Modula-3. In this paper, we describe the Vortex compiler's intermediate language, internal structure, and optimization suite, and then we report the results of experiments assessing the effectiveness of different combinations of optimizations on sizable applications across these four languages. We characterize the benchmark programs in terms of a collection of static and dynamic metrics, intended to quantify aspects of the "object-orientedness" of a program.