Netlib BLAS functions don't work correctly

[opervush]

Summary

This problem happened when we link Netlib BLAS and use oneMKL backend with compile-time dispatching. If we link -lonemkl_blas_xxx before -lcblas then cblas_gemm function (from Netlib) doesn't work correctly. We don't see any errors or warnings, but the output matrix doesn't even changed after test.

Version

latest, git hash 45c43ed

Environment

• oneMKL 2022.2
• Netlib BLAS 3.9.1
• Ubuntu 20.04.2 LTS
• Intel(R) oneAPI DPC++/C++ Compiler 2022.2.0

Steps to reproduce

reproducer.zip

• clone the repo
• build oneMKL Interfaces with only oneMKL backend
• build Netlib BLAS library
• build the reproducer with the following string: icpx -fsycl -I${CBLASROOT}/include/ -I${ONEMKLROOT}/include/ gemm_usm.cpp -o gemm_usm.out -L${ONEMKLROOT}/lib -lonemkl_blas_mklcpu -L${CBLASROOT}/lib/ -lcblas
• run gemm_usm.out

Observed behavior

Output:
C[0] = 1 C[1] = 1 C[2] = 1 C[3] = 1 C[4] = 1 C[5] = 1 C[6] = 1 C[7] = 1 C[8] = 1 C[9] = 1

Expected behavior

Output:
C[0] = 1.58397 C[1] = 1.69333 C[2] = 0.511891 C[3] = 0.30601 C[4] = 0.239454 C[5] = 1.61384 C[6] = 0.5664 C[7] = 1.13597 C[8] = 2.24034 C[9] = 1.33806

We can get the correct output in case of link line: icpx -fsycl -I${CBLASROOT}/include/ -I${ONEMKLROOT}/include/ gemm_usm.cpp -o gemm_usm.out -L${CBLASROOT}/lib/ -lcblas -L${ONEMKLROOT}/lib -lonemkl_blas_mklcpu or icpx -fsycl -I${CBLASROOT}/include/ -I${ONEMKLROOT}/include/ gemm_usm.cpp -o gemm_usm.out -L${ONEMKLROOT}/lib -lonemkl -L${CBLASROOT}/lib/ -lcblas

[mmeterel]

@dnhsieh-intel I know you fixed the symbol conflict issue between BLAS CPU backends and Netlib reference library in #251. However, this looks like we still have some issues for some cases. Do you want to take a look at this one?

[dnhsieh-intel]

Sure! Let me check.

[dnhsieh-intel]

Hi @opervush, here are my observations, although they don't fully explain what happened.

First, since libcblas depends on libblas, the problem can be resolved by adding -lblas to the link line, that is:

icpx -fsycl -I${CBLASROOT}/include/ -I${ONEMKLROOT}/include/ gemm_usm.cpp -o gemm_usm.out -L${ONEMKLROOT}/lib -lonemkl_blas_mklcpu -L${CBLASROOT}/lib -lcblas -lblas

It's mysterious to me that -lblas was linked using the two workable link lines you mentioned without including it explicitly.

I saw the following warning when I compiled it the first time, but not afterwards:

/usr/bin/ld: warning: libblas.so.3, needed by <netlib_path>/lib//libcblas.so, not found (try using -rpath or -rpath-link)

Please try if adding -lblas works for you.