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Re: [PATCH 4/5] tree-walk: unroll get_mode since loop boundaries are well-known

From
Nguyen Thai Ngoc Duy <pclouds@gmail.com>
Date
Apr 2, 2011, 09:28 UTC
Message-ID
<BANLkTi=QK0_P3=rGFLXzZzk7c7JSNxuBmA@mail.gmail.com>
In-Reply-To
<1301535481-1085-4-git-send-email-dpmcgee@gmail.com>
On Thu, Mar 31, 2011 at 8:38 AM, Dan McGee <dpmcgee@gmail.com> wrote:
> We know our mode entry in our tree objects should be 5 or 6 characters
> long. This change both enforces this fact and also unrolls the parsing
> of the information giving the compiler more room for optimization of the
> operations.

I'm skeptical. Did you measure signficant gain after this patch? I looked at asm output with -O3 and failed to see the compiler doing anything fancy. Perhaps it's because I'm on x86 with quite small register set.

-- 
Duy
Previous: Dan McGeeNext: Dan McGee
Message 10 of 30 in “diff_tree_sha1: skip diff_tree if old == new”
  1. 1/5 diff_tree_sha1: skip diff_tree if old == newDan McGee, Mar 31, 2011
  2. 2/5 tree-walk: drop unused parameter from match_dir_prefixDan McGee, Mar 31, 2011
  3. Dan McGeeAug 30, 2011
  4. 3/5 tree-walk: micro-optimization in tree_entry_interestingDan McGee, Mar 31, 2011
  5. Nguyen Thai Ngoc DuyApr 3, 2011
  6. Junio C HamanoApr 3, 2011
  7. Dan McGeeApr 5, 2011
  8. tree_entry_interesting: inline strncmp()Nguyễn Thái Ngọc Duy, Apr 4, 2011
  9. 4/5 tree-walk: unroll get_mode since loop boundaries are well-knownDan McGee, Mar 31, 2011
  10. Nguyen Thai Ngoc DuyApr 2, 2011
  11. Dan McGeeApr 2, 2011
  12. Nguyen Thai Ngoc DuyApr 3, 2011
  13. Erik Faye-LundApr 4, 2011
  14. Andreas EricssonApr 4, 2011
  15. Junio C HamanoApr 4, 2011
  16. Dan McGeeApr 5, 2011
  17. Antriksh PanyApr 5, 2011
  18. Dan McGeeApr 6, 2011
  19. 5/5 tree-walk: match_entry microoptimizationDan McGee, Mar 31, 2011
  20. Nguyen Thai Ngoc DuyApr 2, 2011
  21. Dan McGeeApr 2, 2011
  22. Nguyen Thai Ngoc DuyMar 31, 2011
  23. Dan McGeeMar 31, 2011
  24. Junio C HamanoApr 1, 2011
  25. Nguyen Thai Ngoc DuyMay 3, 2011
  26. Fwd: [PATCH 1/5] diff_tree_sha1: skip diff_tree if old == newDan McGee, Apr 2, 2011
  27. Dan McGeeAug 30, 2011
  28. Junio C HamanoAug 30, 2011
  29. 1/2 tree-walk: drop unused parameter from match_dir_prefixDan McGee, Sep 9, 2011
  30. 2/2 tree-walk: micro-optimization in tree_entry_interestingDan McGee, Sep 9, 2011

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