BLIS 0.8.0 now available

[Field Van Zee]

Friends of BLIS,

BLIS 0.8.0 is now available.

The marquee features introduced in BLIS 0.8.0 are: (1) optimized sgemm kernels targeting skinny/small problems on x86_64 microarchitectures, (2) support for the level-3 BLAS-like operation gemmt, and (3) new performance graphs showcasing performance of BLIS and other implementations on an AMD Epyc 7742 Zen2 "Rome" server. These graphs may be found on the web at [1] and [2].

Items (1) and (3) were made possible thanks to support and hardware access provided by Oracle while (2) was made possible thanks to our partnership with AMD.

A complete list of improvements present in 0.8.0 follows.

Framework:
- Implemented support for the level-3 operation gemmt, which performs a gemm on only the lower or only the upper triangle of a square matrix C. For now, only the conventional/large code path (and not the sup code path) is implemented. This support also includes gemmt APIs in the BLAS and CBLAS compatibility layers. (AMD)
- Added a C++ template header, blis.hh, containing a BLAS-inspired wrapper to a set of polymorphic CBLAS-like function wrappers defined in another header, cblas.hh. These headers are installed only when running the 'install' target with the INSTALL_HH variable set to yes.
- Disallow randv, randm, randnv, and randnm from producing vectors and matrices with 1-norms of zero.
- Changed the behavior of user-initialized rntm_t objects so that packing of A and B is disabled by default. (Kiran Varaganti)
- Transitioned to using bool keyword instead of the previous integer-based bool_t typedef. (RuQing Xu)
- Updated all inline function definitions to use the cpp macro BLIS_INLINE instead of the static keyword. (Giorgos Margaritis, Devin Matthews)
- Relocated #include "cpuid.h" directive from bli_cpuid.h to bli_cpuid.c so that applications can #include both blis.h and cpuid.h. (Bhaskar Nallani, Devin Matthews)
- Defined xerbla_array_() to complement the netlib routine xerbla_array(). (Isuru Fernando)
- Replaced the previously broken ref99 sandbox with a simpler, functioning alternative. (Francisco Igual)
- Fixed a harmless bug whereby herk was calling trmm-related code for determining the blocksize of KC in the 4th loop.

Kernels:
- Implemented a full set of sgemmsup assembly millikernels and microkernels for the 'haswell' kernel set.
- Implemented POWER10 sgemm and dgemm microkernels. (Nicholai Tukanov)
- Added two kernels (dgemm and dpackm) that employ ARM SVE vector extensions. (Guodong Xu)
- Implemented explicit beta = 0 handling in the sgemm microkernel in
bli_gemm_armv7a_int_d4x4.c. This omission was causing testsuite failures in
the new gemmt testsuite module for 'cortexa15' builds given that the gemmt
correctness check relies on gemm with beta = 0.
- Updated void* function arguments in reference packm kernels to use the native pointer type, and fixed a related dormant type bug in bli_kernels_knl.h.
- Fixed missing restrict qualifier in sgemm microkernel prototype for 'knl' kernel set header.
- Added some missing n = 6 edge cases to dgemmsup kernels.
- Fixed an erroneously disabled edge case optimization in gemmsup variant code.
- Various bugfixes and cleanups to dgemmsup kernels.

Build system:
- Implemented runtime subconfiguration selection override via BLIS_ARCH_TYPE. (decandia50)
- Output the python found during configure into the PYTHON variable set in build/config.mk. (AMD)
- Added configure support for Intel oneAPI via the CC environment variable. (Ajay Panyala, Devin Matthews)
- Use -O2 for all framework code, potentially avoiding intermittent issues with f2c'ed packed and banded code. (Devin Matthews)
- Tweaked 'zen2' subconfiguration's cache blocksizes and registered full suite of sgemm and dgemm millikernels.
- Use the -fomit-frame-pointer compiler optimization option in the 'haswell' and 'skx' subconfigurations. (Jeff Diamond, Devin Matthews)
- Tweaked Makefiles in test, test/3, and test/sup so that running any of the usual targets without having first built BLIS results in a helpful error message.
- Add support for --complex-return=[gnu|intel] to configure, which allows the user to toggle between the GNU and Intel return value conventions for functions such as cdotc, cdotu, zdotc, and zdotu.
- Updates to cortexa9, cortexa53 compilation flags. (Dave Love)

Testing:
- Added a gemmt module to the testsuite and a standalone test driver to the test directory, both of which exercise the new gemmt functionality. (AMD)
- Support creating matrices with small or large leading dimensions in test/sup test drivers.
- Support executing test/sup drivers with unpacked or packed matrices.
- Added optional numactl usage to test/3/runme.sh.
- Updated and/or consolidated octave scripts in test/3 and test/sup.
- Increased dotxaxpyf testsuite thresholds to avoid false MARGINAL results during normal execution. (nagsingh)

Documentation:
- Added Epyc 7742 Zen2 ("Rome") performance results (single- and multithreaded) to Performance.md and PerformanceSmall.md. (Jeff Diamond)
- Documented gemmt APIs in BLISObjectAPI.md and BLISTypedAPI.md. (AMD)
- Documented commonly-used object mutator functions in BLISObjectAPI.md. (Jeff Diamond)
- Relocated the operation indices of BLISObjectAPI.md and BLISTypedAPI.md to appear immediately after their respective tables of contents. (Jeff Diamond)
- Added missing perl prerequisite to BuildSystem.md. (pkubaj, Dilyn Corner)
- Fixed missing conjy parameter in BLISTypedAPI.md documentation for her2 and syr2. (Robert van de Geijn)
- Fixed incorrect link to shiftd in BLISTypedAPI.md. (Jeff Diamond)
- Mention example code at the top of BLISObjectAPI.md and BLISTypedAPI.md.
- Minor updates to README.md, FAQ.md, Multithreading.md, and Sandboxes.md documents.

Special thanks to Jeff Diamond, Devin Matthews, Guodong Xu, Nicholai Tukanov, Ajay Panyala, RuQing Xu, Isuru Fernando, Francisco Igual, Bhaskar Nallani, Giorgos Margaritis, Dave Love, Dilyn Corner, Robert van de Geijn, and the CPU libraries group at AMD for their numerous helpful bug reports, suggestions, contributions, and help in tracking down issues. (And please forgive me if I inadvertently left out your name.) Please continue to give us feedback--it is always appreciated!

As always, a full list of changes is available in the CHANGELOG:

  https://github.com/flame/blis/blob/master/CHANGELOG

Please let us know if you have any questions.

Field

[1] https://github.com/flame/blis/blob/master/docs/Performance.md
[2] https://github.com/flame/blis/blob/master/docs/PerformanceSmall.md