error: register 'sp' unsuitable for global register variables on this target

[nickdesaulniers]

on linux-next with ToT LLVM, after hitting #1855 then #1856, I then hit:

$ ARCH=arm make LLVM=1 -j128 KBUILD_CFLAGS="-Wno-builtin-macro-redefined -Wno-incompatible-library-redeclaration"
...
  UPD     include/generated/timeconst.h
In file included from kernel/bounds.c:13:
In file included from ./include/linux/log2.h:12:
In file included from ./include/linux/bitops.h:68:
In file included from ./arch/arm/include/asm/bitops.h:28:
In file included from ./include/linux/irqflags.h:17:
./arch/arm/include/asm/percpu.h:10:51: error: register 'sp' unsuitable for global register variables on this target
register unsigned long current_stack_pointer asm ("sp");
                                                  ^

I don't see a Makefile rule for kernel/bounds.o; I wonder if it get's consumed to produce include/generated/timeconst.h perhaps? And perhaps the header isn't being built with CLANG_FLAGS such as --target (or is assuming x86_64 host rather than arm target)?

[nickdesaulniers]

Strange https://reviews.llvm.org/D151741 does indeed avoid this error...closing as dup of #1857.