Re: [PATCH] RISC-V: Fix vfirst/vmsbf/vmsif/vmsof ratio attributes

[Kito Cheng <kito.cheng@gmail.com>]

LGTM :)

On Mon, Jan 22, 2024 at 10:49 AM Juzhe-Zhong <juzhe.zhong@rivai.ai> wrote:
>
> vfirst/vmsbf/vmsif/vmsof instructions are supposed to demand ratio instead of demanding sew_lmul.
> But my previous typo makes VSETVL PASS miss honor the risc-v v spec.
>
> Consider this following simple case:
>
> int foo4 (void * in, void * out)
> {
>   vint32m1_t v = __riscv_vle32_v_i32m1 (in, 4);
>   v = __riscv_vadd_vv_i32m1 (v, v, 4);
>   vbool32_t mask = __riscv_vreinterpret_v_i32m1_b32(v);
>   mask = __riscv_vmsof_m_b32(mask, 4);
>   return __riscv_vfirst_m_b32(mask, 4);
> }
>
> Before this patch:
>
> foo4:
>         vsetivli        zero,4,e32,m1,ta,ma
>         vle32.v v1,0(a0)
>         vadd.vv v1,v1,v1
>         vsetvli zero,zero,e8,mf4,ta,ma    ----> redundant.
>         vmsof.m v2,v1
>         vfirst.m        a0,v2
>         ret
>
> After this patch:
>
> foo4:
>         vsetivli        zero,4,e32,m1,ta,ma
>         vle32.v v1,0(a0)
>         vadd.vv v1,v1,v1
>         vmsof.m v2,v1
>         vfirst.m        a0,v2
>         ret
>
> Confirm RVV spec and Clang, this patch makes VSETVL PASS match the correct behavior.
>
> Tested on both RV32/RV64, no regression.
>
> gcc/ChangeLog:
>
>         * config/riscv/vector.md: Fix vfirst/vmsbf/vmsof ratio attributes.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/riscv/rvv/vsetvl/attribute-1.c: New test.
>
> ---
>  gcc/config/riscv/vector.md                    |  2 +-
>  .../gcc.target/riscv/rvv/vsetvl/attribute-1.c | 47 +++++++++++++++++++
>  2 files changed, 48 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/vsetvl/attribute-1.c
>
> diff --git a/gcc/config/riscv/vector.md b/gcc/config/riscv/vector.md
> index cfc54ae5eac..307d9a8c952 100644
> --- a/gcc/config/riscv/vector.md
> +++ b/gcc/config/riscv/vector.md
> @@ -433,7 +433,7 @@
>                           vialu,vshift,vicmp,vimul,vidiv,vsalu,\
>                           vext,viwalu,viwmul,vicalu,vnshift,\
>                           vimuladd,vimerge,vaalu,vsmul,vsshift,\
> -                         vnclip,viminmax,viwmuladd,vmffs,vmsfs,\
> +                         vnclip,viminmax,viwmuladd,\
>                           vmiota,vmidx,vfalu,vfmul,vfminmax,vfdiv,\
>                           vfwalu,vfwmul,vfsqrt,vfrecp,vfsgnj,vfcmp,\
>                           vfmerge,vfcvtitof,vfcvtftoi,vfwcvtitof,\
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/attribute-1.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/attribute-1.c
> new file mode 100644
> index 00000000000..28dcf986bac
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/attribute-1.c
> @@ -0,0 +1,47 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64gcv -mabi=lp64d -O3" } */
> +
> +#include "riscv_vector.h"
> +
> +int
> +foo (void *in, void *out)
> +{
> +  vint32m1_t v = __riscv_vle32_v_i32m1 (in, 4);
> +  v = __riscv_vadd_vv_i32m1 (v, v, 4);
> +  vbool32_t mask = __riscv_vreinterpret_v_i32m1_b32 (v);
> +  return __riscv_vfirst_m_b32 (mask, 4);
> +}
> +
> +int
> +foo2 (void *in, void *out)
> +{
> +  vint32m1_t v = __riscv_vle32_v_i32m1 (in, 4);
> +  v = __riscv_vadd_vv_i32m1 (v, v, 4);
> +  vbool32_t mask = __riscv_vreinterpret_v_i32m1_b32 (v);
> +  mask = __riscv_vmsbf_m_b32 (mask, 4);
> +  return __riscv_vfirst_m_b32 (mask, 4);
> +}
> +
> +int
> +foo3 (void *in, void *out)
> +{
> +  vint32m1_t v = __riscv_vle32_v_i32m1 (in, 4);
> +  v = __riscv_vadd_vv_i32m1 (v, v, 4);
> +  vbool32_t mask = __riscv_vreinterpret_v_i32m1_b32 (v);
> +  mask = __riscv_vmsif_m_b32 (mask, 4);
> +  return __riscv_vfirst_m_b32 (mask, 4);
> +}
> +
> +int
> +foo4 (void *in, void *out)
> +{
> +  vint32m1_t v = __riscv_vle32_v_i32m1 (in, 4);
> +  v = __riscv_vadd_vv_i32m1 (v, v, 4);
> +  vbool32_t mask = __riscv_vreinterpret_v_i32m1_b32 (v);
> +  mask = __riscv_vmsof_m_b32 (mask, 4);
> +  return __riscv_vfirst_m_b32 (mask, 4);
> +}
> +
> +/* { dg-final { scan-assembler-times {vsetivli\s+zero,\s*4,\s*e32,\s*m1,\s*t[au],\s*m[au]} 4 } } */
> +/* { dg-final { scan-assembler-times {vsetivli} 4 } } */
> +/* { dg-final { scan-assembler-not {vsetvli} } } */
> --
> 2.36.3
>