commit 202cf3211adde55ec0f7055afd3c5d75707e285c
author Jianzhou Zhao <jianzhouzh@google.com> Tue Jan 12 21:49:59 2021 +0000
committer Copybara-Service <copybara-worker@google.com> Wed Jan 13 14:34:39 2021 -0800
tree a462c4679ed3f684416f29cfe110e268bddd84d8
parent 5819b31a07bd525c2c06fe0bf0d946f3182d3b77

[MSan] Tweak CopyOrigin

There could be some mis-alignments when copying origins not aligned.

I believe inaligned memcpy is rare so the cases do not matter too much
in practice.

1) About the change at line 50

Let dst be (void*)5,
then d=5, beg=4
so we need to write 3 (4+4-5) bytes from 5 to 7.

2) About the change around line 77.

Let dst be (void*)5,
because of lines 50-55, the bytes from 5-7 were already writen.
So the aligned copy is from 8.

Reviewed-by: eugenis
Differential Revision: https://reviews.llvm.org/D94552
GitOrigin-RevId: 82655c151450e0103a3aa60725639da607f9220c