On Fri, Mar 24, 2023 at 10:59 PM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > On Thu, Mar 23, 2023 at 03:26:14PM +0000, Conor Dooley wrote: > > On Thu, Mar 23, 2023 at 02:59:23PM +0000, Andy Chiu wrote: > > > Some extensions use .option arch directive to selectively enable certain > > > extensions in parts of its assembly code. For example, Zbb uses it to > > > inform assmebler to emit bit manipulation instructions. However, > > > supporting of this directive only exist on GNU assembler and has not > > > landed on clang at the moment, making TOOLCHAIN_HAS_ZBB depend on > > > AS_IS_GNU. > > > > > > While it is still under review at https://reviews.llvm.org/D123515, the > > > upcoming Vector patch also requires this feature in assembler. Thus, > > > provide Kconfig AS_HAS_OPTION_ARCH to detect such feature. Then > > > TOOLCHAIN_HAS_XXX will be turned on automatically when the feature land. > > > > > > Suggested-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > > Signed-off-by: Andy Chiu <andy.chiu@xxxxxxxxxx> > > > --- > > > arch/riscv/Kconfig | 8 +++++++- > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > index 36a5b6fed0d3..4f8fd4002f1d 100644 > > > --- a/arch/riscv/Kconfig > > > +++ b/arch/riscv/Kconfig > > > @@ -244,6 +244,12 @@ config RISCV_DMA_NONCOHERENT > > > config AS_HAS_INSN > > > def_bool $(as-instr,.insn r 51$(comma) 0$(comma) 0$(comma) t0$(comma) t0$(comma) zero) > > > > > > +config AS_HAS_OPTION_ARCH > > > + # https://reviews.llvm.org/D123515 > > > + def_bool y > > > + depends on $(as-instr, .option arch$(comma) +m) > > > + depends on !$(as-instr, .option arch$(comma) -i) > > > > Oh cool, I didn't expect this to work given what Nathan said in his > > mail, but I gave it a whirl and it does seem to. > > The second line is the clever part of this option that I had not > considered, as it checks for something that should error in addition to > something that shouldn't:: > > $ echo '.option arch, -i' | riscv64-linux-gcc -c -o /dev/null -x assembler - > {standard input}: Assembler messages: > {standard input}:1: Error: cannot + or - base extension `i' in .option arch `-i' > > Looking at D123515, I see this same option test is present and appears > to error in the same manner so this should work when that change is > merged. Thanks for checking D123515 Nathan. It was just lucky that It gets the same test coverage in Clang. I would take a look at that aspect in the future if the same happens. > > Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > > I suppose: > > Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > > > > I'd rather it be this way so that it is "hands off", as opposed to the > > version check that would need updating in the future. And I guess it > > means that support for V & IAS will automatically turn on for stable > > kernels too once the LLVM change lands, which is nice ;) > > Very much agreed! > > > Thanks Andy! > > > > > + > > > source "arch/riscv/Kconfig.socs" > > > source "arch/riscv/Kconfig.errata" > > > > > > @@ -442,7 +448,7 @@ config TOOLCHAIN_HAS_ZBB > > > depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbb) > > > depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb) > > > depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900 > > > - depends on AS_IS_GNU > > > + depends on AS_HAS_OPTION_ARCH > > > > > > config RISCV_ISA_ZBB > > > bool "Zbb extension support for bit manipulation instructions" > > > -- > > > 2.17.1 > > > > > > > > Regards, Andy
