Open Source Computer Vision Library
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Liutong HAN 35571be570
Merge pull request #26318 from hanliutong:rvv-intrin-m2
Use LMUL=2 in the RISC-V Vector (RVV) backend of Universal Intrinsic. #26318

The modification of this patch involves the RVV backend of Universal Intrinsic, replacing `LMUL=1` with `LMUL=2`.

Now each Universal Intrinsic type actually corresponds to two RVV vector registers, and each Intrinsic function also operates two vector registers. Considering that algorithms written using Universal Intrinsic usually do not use the maximum number of registers, this can help the RVV backend utilize more register resources without modifying the algorithm implementation

This patch is generally beneficial in performance.

We compiled OpenCV with `Clang-19.1.1` and `GCC-14.2.0` , ran it on `CanMV-k230` and `Banana-Pi F3`. Then we have four scenarios on combinations of compilers and devices. In `opencv_perf_core`, there are 3363 cases, of which:
- 901 (26.8%) cases achieved more than `5%` performance improvement in all four scenarios, and the average speedup of these test cases (compared to scalar) increased from `3.35x` to `4.35x`
- 75 (2.2%) cases had more than `5%` performance loss in all four scenarios, indicating that these cases are better with `LMUL=1` instead of `LMUL=2`. This involves `Mat_Transform`, `hasNonZero`, `KMeans`, `meanStdDev`, `merge` and `norm2`. Among them, `Mat_Transform` only has performance degradation in a few cases (`8UC3`), and the actual execution time of `hasNonZero` is so short that it can be ignored. For `KMeans`, `meanStdDev`, `merge` and `norm2`, we should be able to use the HAL to optimize/restore their performance. (In fact, we have already done this for `merge`  #26216 )

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [ ] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
2024-10-24 10:08:43 +03:00
.github Force contributors to define Apache 2.0 license for the new PRs. 2024-06-28 16:54:14 +03:00
3rdparty Merge pull request #26216 from hanliutong:rvv-hal-merge 2024-10-09 17:07:57 +03:00
apps Merge pull request #25582 from fengyuentau:dnn/dump_pbtxt 2024-05-17 11:07:05 +03:00
cmake Merge pull request #26234 from zachlowry:apply-gcc6-fix-on-each-directory 2024-10-11 17:00:59 +03:00
data Merge pull request #22727 from su77ungr:patch-1 2022-11-17 06:54:25 +00:00
doc Merge pull request #26340 from Kumataro:wa26339 2024-10-22 11:57:14 +03:00
include exclude opencv_contrib modules 2020-02-26 15:12:45 +03:00
modules Merge pull request #26318 from hanliutong:rvv-intrin-m2 2024-10-24 10:08:43 +03:00
platforms Merge pull request #25901 from mshabunin:fix-riscv-aarch-baseline 2024-09-12 18:07:24 +03:00
samples Merge pull request #26212 from jamacias:feature/TickMeter-lasttime 2024-10-14 07:56:24 +03:00
.editorconfig add .editorconfig 2018-10-11 17:57:51 +00:00
.gitattributes cmake: generate and install ffmpeg-download.ps1 2018-06-09 13:19:48 +03:00
.gitignore Merge pull request #17165 from komakai:objc-binding 2020-06-08 18:32:53 +00:00
CMakeLists.txt build: set cmake policy for if(IN_LIST) support 2024-10-16 22:40:47 +03:00
CONTRIBUTING.md migration: github.com/opencv/opencv 2016-07-12 12:51:12 +03:00
COPYRIGHT copyright: 2023 (update) 2023-01-09 09:49:22 +00:00
LICENSE Merge pull request #18073 from vpisarev:apache2_license 2020-08-17 11:49:11 +00:00
README.md Space mistake in README.md 2024-03-03 23:37:07 +05:30
SECURITY.md Updated PGP key for security reports 2023-04-19 19:16:55 +03:00

OpenCV: Open Source Computer Vision Library

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