Rip out non-endomorphism code #826

1. 
   sipa commented at 3:07 am on September 26, 2020: contributor

   As the patent on the GLV optimization has expired, there is no need to keep the slower non-endomorphism code around anymore.
2. sipa force-pushed on Sep 26, 2020
3. sipa force-pushed on Sep 26, 2020
4. 
   elichai commented at 8:51 am on September 26, 2020: contributor

   There’s nothing I love more than a PR that only deletes code :)
5. 
   sipa commented at 8:51 am on September 26, 2020: contributor

   There’s nothing I love more than a PR that only deletes code :)

   Hey it also improves some comments.

6. in .travis.yml:42 in a523e2c996 outdated

   45   fast_finish: true
   46   include:
   47     - compiler: clang
   48       os: linux
   49-      env: HOST=i686-linux-gnu ENDOMORPHISM=yes
   50+      env: HOST=i686-linux-gnu
   

   ---

   ---

   

   elichai commented at 8:55 am on September 26, 2020:

   This job can be completely removed, it’s exactly the same as the one below

   ---

   

   sipa commented at 8:57 am on September 26, 2020:

   One has gmp, the other doesn’t. (same comment applies below).

   ---

   

   elichai commented at 9:01 am on September 26, 2020:

   Oh you’re right, my mistake.
7. in .travis.yml:66 in a523e2c996 outdated

   58@@ -63,7 +59,7 @@ matrix:
   59             - libtool-bin
   60             - libc6-dbg:i386
   61     - compiler: gcc
   62-      env: HOST=i686-linux-gnu ENDOMORPHISM=yes
   

   ---

   ---

   

   elichai commented at 8:55 am on September 26, 2020:

   This job can be completely removed, it’s exactly the same as the one below
8. 
   elichai commented at 9:04 am on September 26, 2020: contributor

   tACK a523e2c9965ff43939abad555fcb8a8aed684d8e

   two nits:

   1. Can you also remove from here: https://github.com/bitcoin-core/secp256k1/blob/master/contrib/travis.sh#L16
   2. Can you update the README to remove the “optionally”:

   Optionally (off by default) use secp256k1’s efficiently-computable endomorphism to split the P multiplicand into 2 half-sized ones.

9. 
   practicalswift commented at 3:21 pm on September 26, 2020: contributor

   ACK a523e2c9965ff43939abad555fcb8a8aed684d8e (modulo merge conflict): diff looks correct
10. sipa cross-referenced this on Sep 26, 2020 from issue Enable endomorphism by default by paulmillr
11. Rip out non-endomorphism code 46f9e0e745
12. sipa force-pushed on Sep 26, 2020
13. 
    sipa commented at 6:14 pm on September 26, 2020: contributor

    Rebased, and:

    1. Can you also remove from here: https://github.com/bitcoin-core/secp256k1/blob/master/contrib/travis.sh#L16
    2. Can you update the README to remove the “optionally”:

    Done.

14. 
    gmaxwell commented at 9:08 pm on September 26, 2020: contributor

    Looks good to me, endo only increases a stripped Os build for me by 456 bytes– so insignificant esp with respect to the performance difference, so I don’t see any reason to keep the other code around even for code size constrained applications (you can get 456 bytes of savings in other ways with less performance impact).
15. tarcieri cross-referenced this on Sep 28, 2020 from issue k256: enable endomorphism optimizations by default; remove non-endomorphism code by tarcieri
16. str4d cross-referenced this on Sep 28, 2020 from issue Use the endomorphism optimization for secp256k1 by str4d
17. 
    jonatack commented at 3:00 pm on September 28, 2020: none

    46f9e0e745accde97742cb542d3c779f5b99b4a8 patch diff LGTM
18. tarcieri referenced this in commit 4858cb0b9d on Sep 28, 2020
19. tarcieri cross-referenced this on Sep 28, 2020 from issue k256: enable endomorphisms by default by tarcieri
20. tarcieri referenced this in commit 3ae2dd112c on Sep 28, 2020
21. 
    practicalswift commented at 7:33 pm on September 28, 2020: contributor

    re-ACK 46f9e0e745accde97742cb542d3c779f5b99b4a8
22. 
    laanwj commented at 8:47 pm on September 28, 2020: member

    ACK 46f9e0e745accde97742cb542d3c779f5b99b4a8

    Looks good to me, endo only increases a stripped Os build for me by 456 bytes– so insignificant esp with respect to the performance difference

    I agree. I also looked at it from that angle, but this is a negligible increase in code size. Not worth keeping an option around for. (on RV64 there is no size difference for the stripped libsecp256k1.so.0.0.0 between master and master with this patch merged)

23. real-or-random cross-referenced this on Sep 29, 2020 from issue Enable GLV optimization? by oleiba
24. 
    elichai commented at 9:58 am on September 29, 2020: contributor

    re-ACK 46f9e0e745accde97742cb542d3c779f5b99b4a8
25. tarcieri referenced this in commit 0db4e7e945 on Sep 29, 2020
26. tarcieri cross-referenced this on Sep 29, 2020 from issue k256: remove non-endomorphism code by tarcieri
27. tarcieri referenced this in commit 2b8ab1c2cb on Sep 30, 2020
28. sipa cross-referenced this on Oct 5, 2020 from issue Increase precision of g1 and g2. by roconnor-blockstream
29. 
    benthecarman commented at 4:07 pm on October 9, 2020: none

    ACK 46f9e0e
30. 
    sipa commented at 0:47 am on October 10, 2020: contributor

    I’d like #822 in before this, as should have all assurances we can get that the lambda-split values indeed stay in range.
31. sipa cross-referenced this on Oct 11, 2020 from issue Rip out non-endomorphism code + dependencies by sipa
32. sipa cross-referenced this on Oct 11, 2020 from issue Switch to our own memcmp function by real-or-random
33. 
    sipa commented at 6:16 pm on October 11, 2020: contributor

    Closing this in favor of #830, which has it rebased on #822 and #825.
34. sipa closed this on Oct 11, 2020

    ---

35. sipa referenced this in commit c6b6b8f1bb on Oct 14, 2020
36. azuchi cross-referenced this on Jan 6, 2022 from issue GLV optimization by default by azuchi

Contributors
sipa elichai practicalswift gmaxwell jonatack laanwj benthecarman