A Formally-Verified C Compiler Supporting Floating-Point Arithmetic

Abstract : Floating-point arithmetic is known to be tricky: roundings, formats, exceptional values. The IEEE-754 standard was a push towards straightening the field and made formal reasoning about floating-point computations easier and flourishing. Unfortunately, this is not sufficient to guarantee the final result of a program, as several other actors are involved: programming language, compiler, architecture. The CompCert formally-verified compiler provides a solution to this problem: this compiler comes with a mathematical specification of the semantics of its source language (a large subset of ISO C90) and target platforms (ARM, PowerPC, x86-SSE2), and with a proof that compilation preserves semantics. In this paper, we report on our recent success in formally specifying and proving correct CompCert's compilation of floating-point arithmetic. Since CompCert is verified using the Coq proof assistant, this effort required a suitable Coq formalization of the IEEE-754 standard; we extended the Flocq library for this purpose. As a result, we obtain the first formally verified compiler that provably preserves the semantics of floating-point programs.
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https://hal.inria.fr/hal-00862689
Contributor : Sylvie Boldo <>
Submitted on : Tuesday, September 17, 2013 - 12:15:24 PM
Last modification on : Thursday, October 3, 2019 - 2:04:03 PM
Long-term archiving on : Friday, December 20, 2013 - 2:21:49 PM

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  • HAL Id : hal-00862689, version 1

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Sylvie Boldo, Jacques-Henri Jourdan, Xavier Leroy, Guillaume Melquiond. A Formally-Verified C Compiler Supporting Floating-Point Arithmetic. 2013. ⟨hal-00862689v1⟩

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