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Differential D7597

Improve constant-timeness on PowerPC
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Authored by deadalnix on Sep 27 2020, 22:52.

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majcosta
Group Reviewers
Restricted Project
Commits
rABC62fa9a6ee5b0: 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

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rABC Bitcoin ABC
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Event Timeline

deadalnix created this revision.Sep 27 2020, 22:52
Herald added a reviewer: Restricted Project. · View Herald TranscriptSep 27 2020, 22:52
deadalnix requested review of this revision.Sep 27 2020, 22:52
teamcity edited the summary of this revision. (Show Details)Sep 27 2020, 22:53

[Bot Message]
One or more PR numbers were detected in the summary.
Links to those PRs have been inserted into the summary for reference.

majcosta accepted this revision.Sep 27 2020, 23:09
This revision is now accepted and ready to land.Sep 27 2020, 23:09
deadalnix updated this revision to Diff 23868.Sep 27 2020, 23:10

rebase

Harbormaster completed remote builds in B12962: Diff 23858.Sep 27 2020, 23:19
This revision was landed with ongoing or failed builds.Sep 27 2020, 23:22
Closed by commit rABC62fa9a6ee5b0: Improve constant-timeness on PowerPC (authored by Tim Ruffing <crypto@timruffing.de>, committed by deadalnix). · Explain Why
This revision was automatically updated to reflect the committed changes.
deadalnix added a commit: rABC62fa9a6ee5b0: Improve constant-timeness on PowerPC.
Harbormaster completed remote builds in B12964: Diff 23868.Sep 27 2020, 23:30

Revision Contents
Changeset List

PathSize
src/
secp256k1/
src/
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Diff 23871

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src/secp256k1/src/scalar_4x64_impl.h

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src/secp256k1/src/scalar_8x32_impl.h

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src/secp256k1/src/util.h

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