segfault in dblat2 in dgemv_HASWELL in OpenBLAS 0.3.5

[susilehtola]

Rebuilding OpenBLAS 0.3.5 on Fedora rawhide (to-be Fedora 30) results in a segfault in the tests

OPENBLAS_NUM_THREADS=1 OMP_NUM_THREADS=1 ./dblat2 < ./dblat2.dat
BUILDSTDERR: Program received signal SIGSEGV: Segmentation fault - invalid memory reference.
BUILDSTDERR: Backtrace for this error:
BUILDSTDERR: #0  0x7f21b3836ca1 in ???
BUILDSTDERR: #1  0x7f21b3835e65 in ???
BUILDSTDERR: #2  0x7f21b368717f in ???
BUILDSTDERR: #3  0x5578496125f2 in dgemv_kernel_4x1
BUILDSTDERR: 	at ../kernel/x86_64/dgemv_n_4.c:143
BUILDSTDERR: #4  0x557849612958 in dgemv_n_HASWELL
BUILDSTDERR: 	at ../kernel/x86_64/dgemv_n_4.c:318
BUILDSTDERR: #5  0x5578487bc333 in dgemv_
BUILDSTDERR: 	at /builddir/build/BUILD/openblas-0.3.5/Rblas/interface/gemv.c:231
BUILDSTDERR: #6  0x5578487b6e8e in dchk1_
BUILDSTDERR: 	at /builddir/build/BUILD/openblas-0.3.5/Rblas/test/dblat2.f:582
BUILDSTDERR: #7  0x5578487bbb02 in dblat2
BUILDSTDERR: 	at /builddir/build/BUILD/openblas-0.3.5/Rblas/test/dblat2.f:305
BUILDSTDERR: #8  0x5578487ad052 in main
BUILDSTDERR: 	at /builddir/build/BUILD/openblas-0.3.5/Rblas/test/dblat2.f:390
BUILDSTDERR: /bin/sh: line 1: 20348 Segmentation fault      (core dumped) OPENBLAS_NUM_THREADS=1 OMP_NUM_THREADS=1 ./dblat2 < ./dblat2.dat
BUILDSTDERR: make[1]: *** [Makefile:32: level2] Error 139
BUILDSTDERR: make[1]: *** Waiting for unfinished jobs....
make[1]: Leaving directory '/builddir/build/BUILD/openblas-0.3.5/Rblas/test'
make: Leaving directory '/builddir/build/BUILD/openblas-0.3.5/Rblas'
BUILDSTDERR: make: *** [Makefile:124: tests] Error 2

The compiler is

gcc                     x86_64 9.0.1-0.4.fc30                      build  22 M
gcc-gfortran            x86_64 9.0.1-0.4.fc30                      build  10 M

and the Rblas version of the library is compiled with

make -C Rblas TARGET=CORE2 DYNAMIC_ARCH=1 DYNAMIC_OLDER=1 USE_THREAD=0 USEOPENMP=0 FC=gfortran CC=gcc 'COMMON_OPT=-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fPIC' 'FCOMMON_OPT=-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fPIC -frecursive' NUM_THREADS=128 LIBPREFIX=libRblas LIBSONAME=libRblas.so INTERFACE64=0

Full build log at
https://kojipkgs.fedoraproject.org//work/tasks/5620/32755620/build.log

[martin-frbg]

Looks like yet another instance of #1964, input operands being declared as readonly despite getting (ab)used as loop counters in the assembly.

[martin-frbg]

Original problem should be fixed now, but I suspect a similar issue with the trsm kernels for Bulldozer and the dtrsm_kernel_RN_haswell.c. (Not corrected yet as I wonder about the correct handling of %8 and %9 in the latter, and %6 and %7 in the Bulldozer kernels)

[martin-frbg]

I believe all bugs of this type should be fixed now (on the develop branch that is planned to become 0.3.6 in about two weeks).

[susilehtola]

Awesome. I've pulled in the patches #2010, #2018, #2019, #2021, #2023, and #2024; hopefully 0.3.5 builds now with gcc 9.

[martin-frbg]

It did in my tests on Kaby Lake (Haswell kernels), I am building the most recent snapshot of gcc9 on Ryzen2700 right now to confirm correct behaviour with -march=znver1 (environment of #2018).

[susilehtola]

Built and tested fine at my end.