Compile for iOS ARMV7

[bitianchi]

When I build openblas for ios armv7, some errors coming up.
I use the following commands to build openblas.

TOOLCHAIN_PATH=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
SYSROOT_PATH=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.0.sdk
make clean
make TARGET=ARMV7 BINARY=64 HOSTCC=clang CC="$TOOLCHAIN_PATH/clang -isysroot $SYSROOT_PATH -arch armv7 -miphoneos-version-min=8.0 -O2" NOFORTRAN=1 libs

The following file is the log.
err.log

[bitianchi]

@martin-frbg Could you please take a look at this?

[martin-frbg]

Indeed looks a lot like #1531 - my patch there was for ARMV8 only, and it could be that ARMV7 needs more and different changes besides replacing the nrm2 functions with their C equivalents. Could you try how much further you get when you replace the four NRM2 entries like we did in #1531 ?

[bitianchi]

The question is I have no idea about the replacement of nrm2_vfpv3.S

[martin-frbg]

If you just comment out the four lines in KERNEL.ARMV7, it should pick up nrm2.c (for SNRM2 and DNRM2) and znrm2.c (for C/ZNRM2) from the basic KERNEL file in kernel/arm.

[brada4]

IphoneOS 11.0 does not run on armv7 processors. It is safe to make it armv8

[xsacha]

Looks like he is targeting iOS 8.0 though:
miphoneos-version-min=8.0

[bitianchi]

Yes, we need to support IOS 8.0

[bitianchi]

One more question:
make TARGET=ARMV7 BINARY=64 HOSTCC=clang CC="$TOOLCHAIN_PATH/clang -isysroot $SYSROOT_PATH -arch armv7 -miphoneos-version-min=8.0 -O2" NOFORTRAN=1 libs
TARGET=ARMV7 is this right?

[martin-frbg]

Yes, that is correct for general ARMv7 cpu support. (Cortex A9 and A15 targets use the same KERNEL.ARMV7 file but have individual settings for cache sizes etc.)

[martin-frbg]

"BINARY=64" probably does not makes sense with the ARMV7 target though (aren't they 32bit cpus, while ARMV8 can support both 32/64 ?)

[bitianchi]

I got it. Thanks

[brada4]

@martin-frbg 32bit support goes away in iOS11
iOS8 supports 64bit apps too.

[martin-frbg]

Should not affect building for earlier versions as seems to be intended here, or does it ? (Not sure what having 64bit support in IOS8 has to do with it)

[brada4]

All phones targeted are ARMv8, just that. Latest ones will not run 32bit binary if they get connected to wifi sometimes....

[xsacha]

To be honest I never target iOS because that platform has a built in BLAS implementation called Accelerate. Saves a lot of headache.