On 6/3/2021 12:51 PM, Seija K. via Gcc-patches wrote:
This patch optimizes and simplifies many of the standard string functions.
Since C99, some of the standard string functions have been changed to use
the restrict modifier.
diff --git a/libgcc/memcmp.c b/libgcc/memcmp.c
index 2348afe1d27f7..74195cf6baf13 100644
--- a/libgcc/memcmp.c
+++ b/libgcc/memcmp.c
@@ -7,10 +7,11 @@ memcmp (const void *str1, const void *str2, size_t count)
const unsigned char *s1 = str1;
const unsigned char *s2 = str2;
- while (count-- > 0)
+ while (count--)
{
- if (*s1++ != *s2++)
- return s1[-1] < s2[-1] ? -1 : 1;
+ if (*s1 != *s2)
+ return *s1 < *s2 ? -1 : 1;
+ s1++, s2++;
}
return 0;
}
I don't see the point behind this change and the similar ones in other
files. I'd like to see some justification for the change beyond just
"this looks cleaner to me".
diff --git a/libgcc/memcpy.c b/libgcc/memcpy.c
index 58b1e405627aa..616df78fd2969 100644
--- a/libgcc/memcpy.c
+++ b/libgcc/memcpy.c
@@ -2,7 +2,7 @@
#include <stddef.h>
void *
-memcpy (void *dest, const void *src, size_t len)
+memcpy (void * restrict dest, const void * restrict src, size_t len)
I would expect prototype fixes like this within libgcc to be reasonably
safe.
diff --git a/libiberty/memcpy.c b/libiberty/memcpy.c
index 7f67d0bd1f26c..d388ae7f3506b 100644
--- a/libiberty/memcpy.c
+++ b/libiberty/memcpy.c
@@ -19,7 +19,7 @@ Copies @var{length} bytes from memory region
@var{in} to region
void bcopy (const void*, void*, size_t);
PTR
-memcpy (PTR out, const PTR in, size_t length)
+memcpy (PTR restrict out, const PTR restrict in, size_t length)
It's not entirely clear that using "restrict" is safe because libiberty
is used by so many other projects which may be building with old
compilers, non-gcc compilers, etc.
Generally the way to handle this is to use an autoconf check to confirm
that the tools can handle the feature you want to use and ensure there's
a fallback when they can't.
Jeff
