Re: [PATCH] newlib: riscv: Remove unnecessary byte load/store for stpcpy()/strcpy()

Thanks.  Patch pushed.

-- Jeff J.

On Tue, Apr 15, 2025 at 9:02 AM Kito Cheng <[email protected]> wrote:

> This patch LGTM, thanks :)
>
> On Tue, Apr 15, 2025 at 6:19 AM Jeff Johnston <[email protected]> wrote:
> >
> > Kito, this patch seemed to slip through the cracks.  Could you please
> review?
> >
> > Thanks
> >
> > -- Jeff J.
> >
> > On Sun, Apr 6, 2025 at 4:04 PM Eric Salem <[email protected]> wrote:
> >>
> >> For architectures where XLEN is 32 bits, when detecting a null byte, a
> >> word is read at a time. Once a null is found in the word, its precise
> >> location is then determined. Make clear to the compiler that if the
> >> first three bytes are not null, the last byte must be null, and does not
> >> need to be read from the source string, since its value is always zero.
> >>
> >> Reviewed-by: Christian Herber <[email protected]>
> >> Signed-off-by: Eric Salem <[email protected]>
> >> ---
> >>  newlib/libc/machine/riscv/rv_string.h | 6 +++---
> >>  1 file changed, 3 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/newlib/libc/machine/riscv/rv_string.h
> b/newlib/libc/machine/riscv/rv_string.h
> >> index 362f66a024bf..7754303064c9 100644
> >> --- a/newlib/libc/machine/riscv/rv_string.h
> >> +++ b/newlib/libc/machine/riscv/rv_string.h
> >> @@ -82,8 +82,8 @@ static __inline char *__libc_strcpy(char *dst, const
> char *src, bool ret_start)
> >>            if (!(*dst++ = src[0])) return dst0;
> >>            if (!(*dst++ = src[1])) return dst0;
> >>            if (!(*dst++ = src[2])) return dst0;
> >> -          if (!(*dst++ = src[3])) return dst0;
> >>            #if __riscv_xlen == 64
> >> +            if (!(*dst++ = src[3])) return dst0;
> >>              if (!(*dst++ = src[4])) return dst0;
> >>              if (!(*dst++ = src[5])) return dst0;
> >>              if (!(*dst++ = src[6])) return dst0;
> >> @@ -94,13 +94,13 @@ static __inline char *__libc_strcpy(char *dst,
> const char *src, bool ret_start)
> >>            if (!(*dst++ = src[0])) return dst - 1;
> >>            if (!(*dst++ = src[1])) return dst - 1;
> >>            if (!(*dst++ = src[2])) return dst - 1;
> >> -          if (!(*dst++ = src[3])) return dst - 1;
> >>            #if __riscv_xlen == 64
> >> +            if (!(*dst++ = src[3])) return dst - 1;
> >>              if (!(*dst++ = src[4])) return dst - 1;
> >>              if (!(*dst++ = src[5])) return dst - 1;
> >>              if (!(*dst++ = src[6])) return dst - 1;
> >> -            dst0 = dst;
> >>            #endif
> >> +          dst0 = dst;
> >>          }
> >>
> >>        *dst = 0;
> >> --
> >> 2.49.0
> >>
>
>