git/list[1] front-page[2] threads[3] people[4] search[5] about
 

Re: [PATCH] Fix maybe-uninitialized warnings found by gcc 9 -flto

From
Stephan Beyer <s-beyer@gmx.net>
Date
Sep 5, 2019, 23:10 UTC
Message-ID
<6894a758-d4ee-92e8-1aab-fc44c9ddcdc3@gmx.net>
In-Reply-To
<20190905225802.GA19526@sigill.intra.peff.net>
On 9/6/19 12:58 AM, Jeff King wrote:
Show 19 quoted lines
> On Fri, Sep 06, 2019 at 12:53:49AM +0200, Stephan Beyer wrote:
>
>> On 9/6/19 12:48 AM, Jeff King wrote:
>>> On Thu, Sep 05, 2019 at 10:24:59AM +0200, Stephan Beyer wrote:
>>>
>>>> Compiler heuristics for detection of potentially uninitialized variables
>>>> may change between compiler versions and enabling link-time optimization
>>>> may find new warnings.  Indeed, compiling with gcc 9.2.1 and enabled
>>>> link-time optimization feature resulted in a few hits that are fixed by
>>>> this patch in the most naïve way.  This allows to compile git using the
>>>> DEVELOPER=1 switch (which sets -Werror) and using the -flto flag.
>>>
>>> Lots of discussion in this thread. Let's try to turn it into some
>>> patches. :)
>>
>> I thought the same and just sent my version of it. :D
>
> Yeah, I see that our mails crossed. :) I like some of my versions
> better, but I'm OK with either (or a mix-and-match).

I took a quick glance at yours. I also noticed the issue you address in [PATCH 2/6], but I was unsure if this is the way to go (I'm only occasionally reading on this list). I would prefer your patch series, with maybe one exception...

The thing is: I had *exactly* the same commit like your [PATCH 6/6] (except for the commit message and for the number), but I dropped it. Why? Because I had the feeling (no particular instance though) that the second locate_object_entry_hash() for each insertion *can* indeed take "too much" time. Also, I was wondering, if the "found = 1" case should be catched as a BUG("should not happen") or something.

I don't care much, though. The performance impact should probably be checked carefully.

Stephan
Previous: Jeff KingNext: Jeff King
Message 19 of 23 in “Fix maybe-uninitialized warnings found by gcc 9 -flto”
  1. Fix maybe-uninitialized warnings found by gcc 9 -fltoStephan Beyer, Sep 5, 2019
  2. René ScharfeSep 5, 2019
  3. Jeff KingSep 5, 2019
  4. René ScharfeSep 5, 2019
  5. Junio C HamanoSep 5, 2019
  6. René ScharfeSep 5, 2019
  7. Junio C HamanoSep 5, 2019
  8. Junio C HamanoSep 5, 2019
  9. Junio C HamanoSep 5, 2019
  10. Jeff KingSep 5, 2019
  11. Junio C HamanoSep 5, 2019
  12. Jeff KingSep 5, 2019
  13. 1/6 git-am: handle missing "author" when parsing commitJeff King, Sep 5, 2019
  14. 2/6 pack-objects: use object_id in packlist_alloc()Jeff King, Sep 5, 2019
  15. 3/6 bulk-checkin: zero-initialize hashfile_checkpointJeff King, Sep 5, 2019
  16. 4/6 diff-delta: set size out-parameter to 0 for NULL deltaJeff King, Sep 5, 2019
  17. Stephan BeyerSep 5, 2019
  18. Jeff KingSep 5, 2019
  19. Stephan BeyerSep 5, 2019
  20. Jeff KingSep 6, 2019
  21. 6/6 pack-objects: drop packlist index_pos optimizationJeff King, Sep 6, 2019
  22. 5/6 test-read-cache: drop namelen variableJeff King, Sep 5, 2019
  23. 6/6 pack-objects: drop packlist index_pos optimizationJeff King, Sep 5, 2019

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.