[flang] OpenBLAS 0.3.26 not buildable on windows with flang 18

[h-vetinari]

I had been under the impression that flang had already been able to compile BLAS/LAPACK and OpenBLAS successfully (c.f. #64750, #67675, #70458).

However, while trying¹ to use flang 18.1.2 to compile the latest OpenBLAS 0.3.26 (aside from from backporting a small fix due to flang 18 being stricter on unknown flags), things fail pretty early with what looks like a parsing problem...

[2005/19090] Building Fortran object CMakeFiles\LAPACK_OVERRIDES.dir\lapack-netlib\SRC\sgbcon.f.obj
FAILED: CMakeFiles/LAPACK_OVERRIDES.dir/lapack-netlib/SRC/sgbcon.f.obj 
%BUILD_PREFIX%\Library\bin\flang.exe -I%SRC_DIR%\lapack-netlib\SRC -I%SRC_DIR%\lapack-netlib\LAPACKE\include -ffixed-line-length-72 -o CMakeFiles\LAPACK_OVERRIDES.dir\lapack-netlib\SRC\sgbcon.f.obj -c CMakeFiles\LAPACK_OVERRIDES.dir\lapack-netlib\SRC\sgbcon.f-pp.f
error: loc("D:\\bld\\openblas_1711274852957\\work\\lapack-netlib\\SRC\\sgbcon.f":206:7): operation with block successors must terminate its parent block

error: verification of lowering to FIR failed

Looking for the error message, the only open issue I've found is #61281, but that issue explicitly says "This case is OK in OpenMP". There's also #74348 (which got fixed in 18.1) and #72792 (where it's unclear when/what was fixed).

Footnotes

1. despite the title of the PR, the error here is for the case with USE_OPENMP=0, i.e. no OpenMP; with OpenMP I still have to fix stuff around OpenMP_Fortran ↩

[llvmbot]

@llvm/issue-subscribers-flang-ir

Author: None (h-vetinari)

I had been under the impression that flang had already been able to compile BLAS/LAPACK and OpenBLAS successfully (c.f. https://github.com//issues/64750, https://github.com//issues/67675, https://github.com//issues/70458).

However, while trying¹ to use flang 18.1.2 to compile the latest OpenBLAS 0.3.26 (aside from from backporting a small fix due to flang 18 being stricter on unknown flags), things fail pretty early with what looks like a parsing problem...

[2005/19090] Building Fortran object CMakeFiles\LAPACK_OVERRIDES.dir\lapack-netlib\SRC\sgbcon.f.obj
FAILED: CMakeFiles/LAPACK_OVERRIDES.dir/lapack-netlib/SRC/sgbcon.f.obj 
%BUILD_PREFIX%\Library\bin\flang.exe -I%SRC_DIR%\lapack-netlib\SRC -I%SRC_DIR%\lapack-netlib\LAPACKE\include -ffixed-line-length-72 -o CMakeFiles\LAPACK_OVERRIDES.dir\lapack-netlib\SRC\sgbcon.f.obj -c CMakeFiles\LAPACK_OVERRIDES.dir\lapack-netlib\SRC\sgbcon.f-pp.f
error: loc("D:\\bld\\openblas_1711274852957\\work\\lapack-netlib\\SRC\\sgbcon.f":206:7): operation with block successors must terminate its parent block

error: verification of lowering to FIR failed

Looking for the error message, the only open issue I've found is #61281, but that issue explicitly says "This case is OK in OpenMP". There's also #74348 (which got fixed in 18.1) and #72792 (where it's unclear when/what was fixed).

Footnotes

1. despite the title of the PR, the error here is for the case with USE_OPENMP=0, i.e. no OpenMP; with OpenMP I still have to fix stuff around OpenMP_Fortran ↩

[h-vetinari]

Hm, this might somehow be related to #86459?