On Sat, Aug 7, 2021 at 4:53 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > On Fri, Aug 06, 2021 at 10:27:01AM -0700, Nick Desaulniers wrote: > > LLVM_IAS=1 controls enabling clang's integrated assembler via > > -integrated-as. This was an explicit opt in until we could enable > > assembler support in Clang for more architecures. Now we have support > > and CI coverage of LLVM_IAS=1 for all architecures except a few more > > bugs affecting s390 and powerpc. > > The powerpc and s390 folks have been testing with clang, I think they > should have been on CC for this change (done now). > > > This commit flips the default from opt in via LLVM_IAS=1 to opt out via > > LLVM_IAS=0. CI systems or developers that were previously doing builds > > with CC=clang or LLVM=1 without explicitly setting LLVM_IAS must now > > explicitly opt out via LLVM_IAS=0, otherwise they will be implicitly > > opted-in. > > > > This finally shortens the command line invocation when cross compiling > > with LLVM to simply: > > > > $ make ARCH=arm64 LLVM=1 > > > > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > I am still not really sure how I feel about this. I would prefer not to > break people's builds but I suppose this is inevitabile eventually. > > A little support matrix that I drafted up where based on ARCH and clang > version for LLVM_IAS=1 support: > > | 10.x | 11.x | 12.x | 13.x | 14.x | > ARCH=arm | NO | NO | NO | YES | YES | > ARCH=arm64 | NO | YES | YES | YES | YES | > ARCH=i386 | YES | YES | YES | YES | YES | > ARCH=mips* | YES | YES | YES | YES | YES | > ARCH=powerpc | NO | NO | NO | NO | NO | > ARCH=s390 | NO | NO | NO | NO | NO | > ARCH=x86_64 | NO | YES | YES | YES | YES | > > The main issue that I have with this change is that all of these > architectures work fine with CC=clang and their build commands that used > to work fine will not with this change, as they will have to specify > LLVM_IAS=0. I think that making this change for LLVM=1 makes sense but > changing the default for just CC=clang feels like a bit much at this > point in time. I would love to hear from others on this though, I am not > going to object much further than this. > > Regardless of that concern, this patch does what it says so: > > Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx> Applied to linux-kbuild. Thanks. -- Best Regards Masahiro Yamada
