On Sun, 19 Jul 2020 at 07:45, Palmer Dabbelt <pal...@dabbelt.com> wrote: > > On Tue, 07 Jul 2020 22:43:54 PDT (-0700), maoche...@eswin.com wrote: > > Enable ARCH_HAS_FAST_MULTIPLIER and ARCH_SUPPORTS_INT128 for better > > code generation. > > These 2 configurations works fine on GCC-9.3 and GCC-10.1 > > > > Signed-off-by: Chenxi Mao <maoche...@eswin.com> > > --- > > arch/riscv/Kconfig | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > index 128192e14ff2..f21b7e5188ca 100644 > > --- a/arch/riscv/Kconfig > > +++ b/arch/riscv/Kconfig > > @@ -26,6 +26,8 @@ config RISCV > > select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU > > select ARCH_WANT_FRAME_POINTERS > > select ARCH_WANT_HUGE_PMD_SHARE if 64BIT > > + select ARCH_HAS_FAST_MULTIPLIER > > + select ARCH_SUPPORTS_INT128 if GCC_VERSION >= 50000 || CC_IS_CLANG > > IIRC int128 is only supported on 64-bit targets, and we already have this > under > RV64I but with a different set of requirements. It looks like everyone has a > different set of requirements, but I feel like CC_HAS_INT128 is the right way > to go. I'm not sure why we have the version check there. Ard: do you know > why > we would need both? >
That looks like copy/paste from the arm64 tree to me, where the names of the libgcc routines were changed at some point, and we only support the newer ones in the kernel. > The fast multiplier one looks fine to me. They're supposed to stay > alphabetical, though. > > > select CLONE_BACKWARDS > > select COMMON_CLK > > select EDAC_SUPPORT