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

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