Fix -Wundef warning on PAGE_COPY_THRESHOLD

The PAGE_COPY_THRESHOLD macro is meant to be overridden by
architecture-specific pagecopy.h, but it is currently done only by
mach; all other architectures use the default.  Check to see if the
macro is defined in addition to whether it is set to a non-zero value.

1 files changed, 8 insertions, 45 deletions

diff --git a/sysdeps/generic/pagecopy.h b/sysdeps/generic/pagecopy.h
index 2c35b71b87..3c81de1b23 100644
--- a/sysdeps/generic/pagecopy.h
+++ b/sysdeps/generic/pagecopy.h
@@ -1,4 +1,4 @@
-/* Macros for copying by pages; used in memcpy, memmove.  Generic macros.
+/* Macros for copying by pages; used in memcpy, memmove.
    Copyright (C) 1995-2014 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,19 +16,15 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-/* This file defines the macro:
+/* The macro PAGE_COPY_FWD_MAYBE defined in memcopy.h is used in memmove if the
+   PAGE_COPY_THRESHOLD macro is set to a non-zero value.  The default is 0,
+   that is copying by pages is not implemented.
 
-   PAGE_COPY_FWD_MAYBE (dstp, srcp, nbytes_left, nbytes)
-
-   which is invoked like WORD_COPY_FWD et al.  The pointers should be at
-   least word aligned.  This will check if virtual copying by pages can and
-   should be done and do it if so.
-
-   System-specific pagecopy.h files should define these macros and then
-   #include this file:
+   System-specific pagecopy.h files that want to support page copying should
+   define these macros:
 
    PAGE_COPY_THRESHOLD
-   -- Minimum size for which virtual copying by pages is worthwhile.
+   -- A non-zero minimum size for which virtual copying by pages is worthwhile.
 
    PAGE_SIZE
    -- Size of a page.
@@ -38,37 +34,4 @@
    The pointers will be aligned to PAGE_SIZE bytes.
 */
 
-
-#if PAGE_COPY_THRESHOLD
-
-#include <assert.h>
-
-#define PAGE_COPY_FWD_MAYBE(dstp, srcp, nbytes_left, nbytes)		      \
-  do									      \
-    {									      \
-      if ((nbytes) >= PAGE_COPY_THRESHOLD &&				      \
-	  PAGE_OFFSET ((dstp) - (srcp)) == 0) 				      \
-	{								      \
-	  /* The amount to copy is past the threshold for copying	      \
-	     pages virtually with kernel VM operations, and the		      \
-	     source and destination addresses have the same alignment.  */    \
-	  size_t nbytes_before = PAGE_OFFSET (-(dstp));			      \
-	  if (nbytes_before != 0)					      \
-	    {								      \
-	      /* First copy the words before the first page boundary.  */     \
-	      WORD_COPY_FWD (dstp, srcp, nbytes_left, nbytes_before);	      \
-	      assert (nbytes_left == 0);				      \
-	      nbytes -= nbytes_before;					      \
-	    }								      \
-	  PAGE_COPY_FWD (dstp, srcp, nbytes_left, nbytes);		      \
-	}								      \
-    } while (0)
-
-/* The page size is always a power of two, so we can avoid modulo division.  */
-#define PAGE_OFFSET(n)	((n) & (PAGE_SIZE - 1))
-
-#else
-
-#define PAGE_COPY_FWD_MAYBE(dstp, srcp, nbytes_left, nbytes) /* nada */
-
-#endif
+#define PAGE_COPY_THRESHOLD 0