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List:       kde-panel-devel
Subject:    D14353: Improve alignment of types
From:       Vlad Zagorodniy <noreply () phabricator ! kde ! org>
Date:       2018-07-27 14:26:23
Message-ID: e2fff8f655813129e9408c1f0fdbdfeb () localhost ! localdomain
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zzag added a comment.


  In D14353#299286 <https://phabricator.kde.org/D14353#299286>, @gladhorn wrote:
  
  > OK, this should be the default for everyone. To have structures packed tight. \
Then the compiler can decide on alignment/padding (potentially depending on \
optimization space vs speed)... Is there any other order for members that makes \
sense?  
  
  IIRC padding stuff, not really. Alignment of each data member depends on its size. \
E.g. if a data member has 8 byte size, then it will be aligned on 8 byte boundaries; \
if a data member has 4 byte size, then it will be aligned on 4 byte boundaries. Now, \
if you have uint32_t before uint64_t, there will be 4 byte hole.  
  Also, I, personally, think this optimization is not worth it. It would matter if we \
have, say, millions of outputs.

REPOSITORY
  R110 KScreen Library

REVISION DETAIL
  https://phabricator.kde.org/D14353

To: gladhorn, #plasma, romangg
Cc: zzag, romangg, plasma-devel, ragreen, Pitel, ZrenBot, lesliezhai, ali-mohamed, \
jensreuterberg, abetts, sebas, apol, mart


[Attachment #3 (text/html)]

<table><tr><td style="">zzag added a comment.
</td><a style="text-decoration: none; padding: 4px 8px; margin: 0 8px 8px; float: \
right; color: #464C5C; font-weight: bold; border-radius: 3px; background-color: \
#F7F7F9; background-image: linear-gradient(to bottom,#fff,#f1f0f1); display: \
inline-block; border: 1px solid rgba(71,87,120,.2);" \
href="https://phabricator.kde.org/D14353">View Revision</a></tr></table><br \
/><div><div><blockquote style="border-left: 3px solid #8C98B8;  color: #6B748C;
          font-style: italic;
          margin: 4px 0 12px 0;
          padding: 8px 12px;
          background-color: #F8F9FC;">
<div style="font-style: normal;
          padding-bottom: 4px;">In <a \
href="https://phabricator.kde.org/D14353#299286" style="background-color: #e7e7e7;  \
border-color: #e7e7e7;  border-radius: 3px;
          padding: 0 4px;
          font-weight: bold;
          color: black;text-decoration: none;">D14353#299286</a>, <a \
href="https://phabricator.kde.org/p/gladhorn/" style="  border-color: #f1f7ff;
              color: #19558d;
              background-color: #f1f7ff;
                border: 1px solid transparent;
                border-radius: 3px;
                font-weight: bold;
                padding: 0 4px;">@gladhorn</a> wrote:</div>
<div style="margin: 0;
          padding: 0;
          border: 0;
          color: rgb(107, 116, 140);"><p>OK, this should be the default for everyone. \
To have structures packed tight. Then the compiler can decide on alignment/padding \
(potentially depending on optimization space vs speed)... Is there any other order \
for members that makes sense?</p></div> </blockquote>

<p>IIRC padding stuff, not really. Alignment of each data member depends on its size. \
E.g. if a data member has 8 byte size, then it will be aligned on 8 byte boundaries; \
if a data member has 4 byte size, then it will be aligned on 4 byte boundaries. Now, \
if you have uint32_t before uint64_t, there will be 4 byte hole.</p>

<p>Also, I, personally, think this optimization is not worth it. It would matter if \
we have, say, millions of outputs.</p></div></div><br \
/><div><strong>REPOSITORY</strong><div><div>R110 KScreen Library</div></div></div><br \
/><div><strong>REVISION DETAIL</strong><div><a \
href="https://phabricator.kde.org/D14353">https://phabricator.kde.org/D14353</a></div></div><br \
/><div><strong>To: </strong>gladhorn, Plasma, romangg<br /><strong>Cc: </strong>zzag, \
romangg, plasma-devel, ragreen, Pitel, ZrenBot, lesliezhai, ali-mohamed, \
jensreuterberg, abetts, sebas, apol, mart<br /></div>



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