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 <[email protected]>
---
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
select CLONE_BACKWARDS
select COMMON_CLK
select EDAC_SUPPORT
--
2.25.1
On Tue, 07 Jul 2020 22:43:54 PDT (-0700), [email protected] 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 <[email protected]>
> ---
> 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?
The fast multiplier one looks fine to me. They're supposed to stay
alphabetical, though.
> select CLONE_BACKWARDS
> select COMMON_CLK
> select EDAC_SUPPORT
On Sun, 19 Jul 2020 at 07:45, Palmer Dabbelt <[email protected]> wrote:
>
> On Tue, 07 Jul 2020 22:43:54 PDT (-0700), [email protected] 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 <[email protected]>
> > ---
> > 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