[2/7] wcsmbs: optimize wcpncpy

Message ID 20190206145850.22003-2-adhemerval.zanella@linaro.org
State New
Headers show
Series
  • [1/7] wcsmbs: optimize wcpcpy
Related show

Commit Message

Adhemerval Zanella Feb. 6, 2019, 2:58 p.m.
This patch rewrites wcpncpy using wcslen, wmemcpy, and wmemset.  This is
similar to the optimization done on stpncpy by 48497aba8e.

Checked on x86_64-linux-gnu.

        * wcsmbs/wcpncpy.c (__wcpcpy): Rewrite using wcslen, wmemcpy, and
	wmemset.
---
 wcsmbs/wcpncpy.c | 58 +++++-------------------------------------------
 1 file changed, 6 insertions(+), 52 deletions(-)

-- 
2.17.1

Comments

Adhemerval Zanella Feb. 26, 2019, 6:12 p.m. | #1
If no one opposes it, I will commit this shortly.

On 06/02/2019 12:58, Adhemerval Zanella wrote:
> This patch rewrites wcpncpy using wcslen, wmemcpy, and wmemset.  This is

> similar to the optimization done on stpncpy by 48497aba8e.

> 

> Checked on x86_64-linux-gnu.

> 

>         * wcsmbs/wcpncpy.c (__wcpcpy): Rewrite using wcslen, wmemcpy, and

> 	wmemset.

> ---

>  wcsmbs/wcpncpy.c | 58 +++++-------------------------------------------

>  1 file changed, 6 insertions(+), 52 deletions(-)

> 

> diff --git a/wcsmbs/wcpncpy.c b/wcsmbs/wcpncpy.c

> index 7568f3b11c..7147affdd5 100644

> --- a/wcsmbs/wcpncpy.c

> +++ b/wcsmbs/wcpncpy.c

> @@ -17,6 +17,7 @@

>     <http://www.gnu.org/licenses/>.  */

>  

>  #include <wchar.h>

> +#include <string.h>

>  

>  #ifdef WCPNCPY

>  # define __wcpncpy WCPNCPY

> @@ -27,59 +28,12 @@

>  wchar_t *

>  __wcpncpy (wchar_t *dest, const wchar_t *src, size_t n)

>  {

> -  wint_t c;

> -  wchar_t *const s = dest;

> -

> -  if (n >= 4)

> -    {

> -      size_t n4 = n >> 2;

> -

> -      for (;;)

> -	{

> -	  c = *src++;

> -	  *dest++ = c;

> -	  if (c == L'\0')

> -	    break;

> -	  c = *src++;

> -	  *dest++ = c;

> -	  if (c == L'\0')

> -	    break;

> -	  c = *src++;

> -	  *dest++ = c;

> -	  if (c == L'\0')

> -	    break;

> -	  c = *src++;

> -	  *dest++ = c;

> -	  if (c == L'\0')

> -	    break;

> -	  if (--n4 == 0)

> -	    goto last_chars;

> -	}

> -      n -= dest - s;

> -      goto zero_fill;

> -    }

> -

> - last_chars:

> -  n &= 3;

> -  if (n == 0)

> +  size_t size = __wcsnlen (src, n);

> +  __wmemcpy (dest, src, size);

> +  dest += size;

> +  if (size == n)

>      return dest;

> -

> -  for (;;)

> -    {

> -      c = *src++;

> -      --n;

> -      *dest++ = c;

> -      if (c == L'\0')

> -	break;

> -      if (n == 0)

> -	return dest;

> -    }

> -

> - zero_fill:

> -  while (n-- > 0)

> -    dest[n] = L'\0';

> -

> -  return dest - 1;

> +  return wmemset (dest, L'\0', (n - size));

>  }

>  

>  #ifndef WCPNCPY

>

Patch

diff --git a/wcsmbs/wcpncpy.c b/wcsmbs/wcpncpy.c
index 7568f3b11c..7147affdd5 100644
--- a/wcsmbs/wcpncpy.c
+++ b/wcsmbs/wcpncpy.c
@@ -17,6 +17,7 @@ 
    <http://www.gnu.org/licenses/>.  */
 
 #include <wchar.h>
+#include <string.h>
 
 #ifdef WCPNCPY
 # define __wcpncpy WCPNCPY
@@ -27,59 +28,12 @@ 
 wchar_t *
 __wcpncpy (wchar_t *dest, const wchar_t *src, size_t n)
 {
-  wint_t c;
-  wchar_t *const s = dest;
-
-  if (n >= 4)
-    {
-      size_t n4 = n >> 2;
-
-      for (;;)
-	{
-	  c = *src++;
-	  *dest++ = c;
-	  if (c == L'\0')
-	    break;
-	  c = *src++;
-	  *dest++ = c;
-	  if (c == L'\0')
-	    break;
-	  c = *src++;
-	  *dest++ = c;
-	  if (c == L'\0')
-	    break;
-	  c = *src++;
-	  *dest++ = c;
-	  if (c == L'\0')
-	    break;
-	  if (--n4 == 0)
-	    goto last_chars;
-	}
-      n -= dest - s;
-      goto zero_fill;
-    }
-
- last_chars:
-  n &= 3;
-  if (n == 0)
+  size_t size = __wcsnlen (src, n);
+  __wmemcpy (dest, src, size);
+  dest += size;
+  if (size == n)
     return dest;
-
-  for (;;)
-    {
-      c = *src++;
-      --n;
-      *dest++ = c;
-      if (c == L'\0')
-	break;
-      if (n == 0)
-	return dest;
-    }
-
- zero_fill:
-  while (n-- > 0)
-    dest[n] = L'\0';
-
-  return dest - 1;
+  return wmemset (dest, L'\0', (n - size));
 }
 
 #ifndef WCPNCPY