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Improve constant-timeness on PowerPC

Description

Improve constant-timeness on PowerPC

Summary:

  • Remove redundant "? 1 : 0" after comparisons in scalar code

This prevents GCC from generating branches on PowerPC in certain
cases.

Fixes #771.

  • Suppress a harmless variable-time optimization by clang in _int_cmov

Follow up on 52a03512c1d800603b5c923c1a28bdba12dadb30

This is a backport of libsecp256k1 PR772

Depends on D7590

Test Plan:

ninja check-secp256k1

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D7597

Details

Provenance
Tim Ruffing <crypto@timruffing.de>Authored on Jul 24 2020, 22:28
deadalnixCommitted on Sep 27 2020, 23:22
deadalnixPushed on Sep 27 2020, 23:22
Reviewer
Restricted Project
Differential Revision
D7597: Improve constant-timeness on PowerPC
Parents
rABCf5b18bcffa86: Fix uninitialized variables in ecmult_multi test
Branches
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