Hi, Xuerui,
On Fri, Jun 23, 2023 at 9:44 PM WANG Xuerui <kernel@xxxxxxxxxx> wrote:
>
> From: WANG Xuerui <git@xxxxxxxxxx>
>
> LLVM/Clang does not see FCSRs as GPRs, so make use of compiler
> built-ins instead for better maintainability with less code.
>
> The existing version cannot be wholly removed though, because the
> built-ins, while available on GCC too, is predicated TARGET_HARD_FLOAT,
> which means soft-float code cannot make use of them.
>
> Signed-off-by: WANG Xuerui <git@xxxxxxxxxx>
> ---
> arch/loongarch/include/asm/loongarch.h | 19 +++++++++++++------
> 1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
> index ac83e60c60d1..eedc313b5241 100644
> --- a/arch/loongarch/include/asm/loongarch.h
> +++ b/arch/loongarch/include/asm/loongarch.h
> @@ -1445,12 +1445,6 @@ __BUILD_CSR_OP(tlbidx)
> #define EXCCODE_INT_START 64
> #define EXCCODE_INT_END (EXCCODE_INT_START + EXCCODE_INT_NUM - 1)
>
> -/* FPU register names */
> -#define LOONGARCH_FCSR0 $r0
> -#define LOONGARCH_FCSR1 $r1
> -#define LOONGARCH_FCSR2 $r2
> -#define LOONGARCH_FCSR3 $r3
> -
> /* FPU Status Register Values */
> #define FPU_CSR_RSVD 0xe0e0fce0
>
> @@ -1487,6 +1481,18 @@ __BUILD_CSR_OP(tlbidx)
> #define FPU_CSR_RU 0x200 /* towards +Infinity */
> #define FPU_CSR_RD 0x300 /* towards -Infinity */
>
> +#ifdef CONFIG_CC_IS_CLANG
> +#define LOONGARCH_FCSR0 0
> +#define LOONGARCH_FCSR1 1
> +#define LOONGARCH_FCSR2 2
> +#define LOONGARCH_FCSR3 3
> +#define read_fcsr(source) __movfcsr2gr(source)
> +#define write_fcsr(dest, val) __movgr2fcsr(dest, val)
> +#else /* CONFIG_CC_IS_CLANG */
> +#define LOONGARCH_FCSR0 $r0
> +#define LOONGARCH_FCSR1 $r1
> +#define LOONGARCH_FCSR2 $r2
> +#define LOONGARCH_FCSR3 $r3
> #define read_fcsr(source) \
> ({ \
> unsigned int __res; \
Now the latest binutils also supports $fcsr, so I suggest to always
use inline asm, and change CONFIG_CC_IS_CLANG to
CONFIG_AS_HAS_FCSR_CLASS. And of course, Patch3 and Patch4 can be
merged then.
Huacai
> @@ -1503,5 +1509,6 @@ do { \
> " movgr2fcsr "__stringify(dest)", %0 \n" \
> : : "r" (val)); \
> } while (0)
> +#endif /* CONFIG_CC_IS_CLANG */
>
> #endif /* _ASM_LOONGARCH_H */
> --
> 2.40.0
>
