Usuba, Optimizing & Trustworthy Bitslicing Compiler Darius Mercadier, Pierre-Évariste Dagand, Lionel Lacassagne, Gilles Muller To cite this version: Darius Mercadier, Pierre-Évariste Dagand, Lionel Lacassagne, Gilles Muller. Usuba, Optimizing & Trustworthy Bitslicing Compiler. WPMVP’18 - Workshop on Programming Models for SIMD/Vector Processing, Feb 2018, Vienna, Austria. 10.1145/3178433.3178437. hal-01657259v2 HAL Id: hal-01657259 https://hal.archives-ouvertes.fr/hal-01657259v2 Submitted on 16 Oct 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Usuba Optimizing & Trustworthy Bitslicing Compiler Darius Mercadier Pierre-Évariste Dagand Lionel Lacassagne Gilles Muller
[email protected] Sorbonne Université, CNRS, Inria, LIP6, F-75005 Paris, France Abstract For example, on input 0110b = 6d, this function returns the Bitslicing is a programming technique commonly used in seventh (note the 0-indexing) element of the table, which is cryptography that consists in implementing a combinational 10d = 1010b. circuit in software. It results in a massively parallel program This implementation suffers from two problems. First, it immune to cache-timing attacks by design. wastes register space: a priori, the input will consume a However, writing a program in bitsliced form requires ex- register of at least 32 bits, leaving 28 bits unused, which treme minutia.