[6/7] wcsmbs: optimize wcsncpy

Message ID 20190206145850.22003-6-adhemerval.zanella@linaro.org
State New
Headers show
Series
  • [1/7] wcsmbs: optimize wcpcpy
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Commit Message

Adhemerval Zanella Feb. 6, 2019, 2:58 p.m.
This patch rewrites wcsncpy using wcsnlen, wmemset, and wmemcpy.  This is
similar to the optimization done on strncpy by f6482cf29d and 6423d4754c.

Checked on x86_64-linux-gnu.

	* wcsmbs/wcsncpy.c (__wcsncpy): Rewrite using wcsnlen, wmemset, and
	wmemcpy.
---
 wcsmbs/wcsncpy.c | 60 ++++--------------------------------------------
 1 file changed, 4 insertions(+), 56 deletions(-)

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 wcsncpy using wcsnlen, wmemset, and wmemcpy.  This is
> similar to the optimization done on strncpy by f6482cf29d and 6423d4754c.
> 
> Checked on x86_64-linux-gnu.
> 
> 	* wcsmbs/wcsncpy.c (__wcsncpy): Rewrite using wcsnlen, wmemset, and
> 	wmemcpy.
> ---
>  wcsmbs/wcsncpy.c | 60 ++++--------------------------------------------
>  1 file changed, 4 insertions(+), 56 deletions(-)
> 
> diff --git a/wcsmbs/wcsncpy.c b/wcsmbs/wcsncpy.c
> index 2fd523c815..d5d7f4ad86 100644
> --- a/wcsmbs/wcsncpy.c
> +++ b/wcsmbs/wcsncpy.c
> @@ -26,62 +26,10 @@
>  wchar_t *
>  __wcsncpy (wchar_t *dest, const wchar_t *src, size_t n)
>  {
> -  wint_t c;
> -  wchar_t *const s = dest;
> -
> -  --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 = n - (dest - s) - 1;
> -      if (n == 0)
> -	return s;
> -      goto zero_fill;
> -    }
> -
> - last_chars:
> -  n &= 3;
> -  if (n == 0)
> -    return s;
> -
> -  do
> -    {
> -      c = *src++;
> -      *++dest = c;
> -      if (--n == 0)
> -	return s;
> -    }
> -  while (c != L'\0');
> -
> - zero_fill:
> -  do
> -    *++dest = L'\0';
> -  while (--n > 0);
> -
> -  return s;
> +  size_t size = __wcsnlen (src, n);
> +  if (size != n)
> +    __wmemset (dest + size, L'\0', n - size);
> +  return __wmemcpy (dest, src, size);
>  }
>  #ifndef WCSNCPY
>  weak_alias (__wcsncpy, wcsncpy)
>

Patch

diff --git a/wcsmbs/wcsncpy.c b/wcsmbs/wcsncpy.c
index 2fd523c815..d5d7f4ad86 100644
--- a/wcsmbs/wcsncpy.c
+++ b/wcsmbs/wcsncpy.c
@@ -26,62 +26,10 @@ 
 wchar_t *
 __wcsncpy (wchar_t *dest, const wchar_t *src, size_t n)
 {
-  wint_t c;
-  wchar_t *const s = dest;
-
-  --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 = n - (dest - s) - 1;
-      if (n == 0)
-	return s;
-      goto zero_fill;
-    }
-
- last_chars:
-  n &= 3;
-  if (n == 0)
-    return s;
-
-  do
-    {
-      c = *src++;
-      *++dest = c;
-      if (--n == 0)
-	return s;
-    }
-  while (c != L'\0');
-
- zero_fill:
-  do
-    *++dest = L'\0';
-  while (--n > 0);
-
-  return s;
+  size_t size = __wcsnlen (src, n);
+  if (size != n)
+    __wmemset (dest + size, L'\0', n - size);
+  return __wmemcpy (dest, src, size);
 }
 #ifndef WCSNCPY
 weak_alias (__wcsncpy, wcsncpy)