,
Robert Rabe,
Eva Darulova
,
Magnus O. Myreen
,
Zachary Tatlock
,
Ramana Kumar
,
Yong Kiam Tan
,
Anthony Fox
Creative Commons Attribution 4.0 International license
Verified compilers such as CompCert and CakeML have become increasingly realistic over the last few years, but their support for floating-point arithmetic has thus far been limited. In particular, they lack the "fast-math-style" optimizations that unverified mainstream compilers perform. Supporting such optimizations in the setting of verified compilers is challenging because these optimizations, for the most part, do not preserve the IEEE-754 floating-point semantics. However, IEEE-754 floating-point numbers are finite approximations of the real numbers, and we argue that any compiler correctness result for fast-math optimizations should appeal to a real-valued semantics rather than the rigid IEEE-754 floating-point numbers. This paper presents RealCake, an extension of CakeML that achieves end-to-end correctness results for fast-math-style optimized compilation of floating-point arithmetic. This result is achieved by giving CakeML a flexible floating-point semantics and integrating an external proof-producing accuracy analysis. RealCake’s end-to-end theorems relate the I/O behavior of the original source program under real-number semantics to the observable I/O behavior of the compiler generated and fast-math-optimized machine code.
@InProceedings{becker_et_al:LIPIcs.ECOOP.2022.1,
author = {Becker, Heiko and Rabe, Robert and Darulova, Eva and Myreen, Magnus O. and Tatlock, Zachary and Kumar, Ramana and Tan, Yong Kiam and Fox, Anthony},
title = {{Verified Compilation and Optimization of Floating-Point Programs in CakeML}},
booktitle = {36th European Conference on Object-Oriented Programming (ECOOP 2022)},
pages = {1:1--1:28},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-225-9},
ISSN = {1868-8969},
year = {2022},
volume = {222},
editor = {Ali, Karim and Vitek, Jan},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2022.1},
URN = {urn:nbn:de:0030-drops-162290},
doi = {10.4230/LIPIcs.ECOOP.2022.1},
annote = {Keywords: compiler verification, compiler optimization, floating-point arithmetic}
}