gmake compilation issue with LLVM clang/flang on Loongarch64 when INTERFACE64=1 is set

[azuresky01]

Compilation of OpenBLAS on loongarch64 is now possible with LLVM clang/flang(flang-new) version 20 and above. Recently I tried to build OpenBLAS 0.3.30 (should also apply to current dev version) on Debian sid with different parameters and found gmake compilation failure when INTERFACE64=1 is set (cmake compilation is OK). See below.

Linux System details: Loongson 3A6000 CPU, Debian sid, kernel 6.12.33+deb13-loong64, GNU Make 4.4.1, clang/flang(flang-new) 20.1.7 both are compiled from the source.

gmake:

building command: CC=/usr/local/llvm-20.1.7/bin/clang FC=/usr/local/llvm-20.1.7/bin/flang make INTERFACE64=1

During the compilation I found that INTERFACE64=1 is not implemented by flang:

...
/usr/local/llvm-20.1.7/bin/flang -O2 -march=loongarch64 -fPIC -c -o sgerq2.o sgerq2.f
...

And finally I got the following error message:

...
/usr/local/llvm-20.1.7/bin/flang -O2 -march=loongarch64   -o zblat2 zblat2.o ../libopenblas_la464p-r0.3.30.a -lm -lpthread -lm -lpthread -L/usr/local/llvm-20.1.7/bin/../lib/loongarch64-unknown-linux-gnu -L/usr/local/llvm-20.1.7/lib/clang/20/lib/loongarch64-unknown-linux-gnu -L/usr/lib/gcc/loongarch64-linux-gnu/14 -L/usr/lib/gcc/loongarch64-linux-gnu/14/../../../../lib64 -L/lib/loongarch64-linux-gnu -L/lib/../lib64 -L/usr/lib/loongarch64-linux-gnu -L/usr/lib/../lib64 -L/lib -L/usr/lib  -lc 
OPENBLAS_NUM_THREADS=1 OMP_NUM_THREADS=1 ./sblat1
 Real BLAS Test Program Results


 Test of subprogram number  1             SDOT 
Bus error
make[1]: *** [Makefile:51: level1] Error 135
...

Cmake compilation with clang/flang 20.1.7 finished without any error though. To fix the above error, based on the hint in cmake/fc.cmake I checked the code in Makefile.system from the lines 1167-1195:

OpenBLAS/Makefile.system

Lines 1167 to 1195 in 993fad6

	ifeq ($(F_COMPILER), $(filter $(F_COMPILER),GFORTRAN FLANGNEW))
	CCOMMON_OPT += -DF_INTERFACE_GFORT
	ifeq ($(F_COMPILER), GFORTRAN)
	FCOMMON_OPT += -Wall
	# make single-threaded LAPACK calls thread-safe #1847
	FCOMMON_OPT += -frecursive
	# work around ABI problem with passing single-character arguments
	FCOMMON_OPT += -fno-optimize-sibling-calls
	#Don't include -lgfortran, when NO_LAPACK=1 or lsbcc
	ifneq ($(NOFORTRAN), 1)
	ifneq ($(NOFORTRAN), 2)
	ifneq ($(NO_LAPACK), 1)
	EXTRALIB += -lgfortran
	endif
	endif
	endif
	endif
	ifdef NO_BINARY_MODE
	ifeq ($(ARCH), $(filter $(ARCH),mips64))
	ifdef BINARY64
	FCOMMON_OPT += -mabi=64
	else
	FCOMMON_OPT += -mabi=n32
	endif
	else ifeq ($(ARCH), $(filter $(ARCH),mips))
	FCOMMON_OPT += -mabi=32
	endif
	else
	ifdef BINARY64

After the line 1193 I add the following lines:

ifeq ($(ARCH), $(filter $(ARCH),loongarch64))
ifdef INTERFACE64
ifneq ($(INTERFACE64), 0)
FCOMMON_OPT +=  -fdefault-integer-8
endif
endif
endif

Then flang can pick up the -fdefault-integer-8 parameter and the compilation error disappears.

@XiWeiGu @martin-frbg

[XiWeiGu]

Thank you for your analysis. You could submit a PR to fix this issue.

[azuresky01]

Thank you for your analysis. You could submit a PR to fix this issue.

Thanks. I have submitted a PR: #5334

[martin-frbg]

Thank you. (Looks like this will probably affect at least MIPS64 too ?)