From 89b84846d10ab803ef1bcf6f9a4cbcdea45f7c96 Mon Sep 17 00:00:00 2001
From: Petr Rockai <me@mornfall.net>
Date: Mon, 22 Jul 2019 20:10:36 +0000
Subject: [PATCH] libc: Optimize memcpy a little.
---
dios/libc/string/memcpy.c | 36 +++++++++++++++++++++++++++++++++---
1 file changed, 33 insertions(+), 3 deletions(-)
diff --git a/dios/libc/string/memcpy.c b/dios/libc/string/memcpy.c
index 55192cdd3..5b95840ee 100644
--- a/dios/libc/string/memcpy.c
+++ b/dios/libc/string/memcpy.c
@@ -6,15 +6,45 @@
#include <string.h>
#include <assert.h>
+#include <stdint.h>
#ifndef REGTEST
-__attribute__((__annotate__("divine.link.always")))
-__attribute__((optnone)) /* do not replace the memmove call below with a (recursive) memcpy */
+__link_always __skipcfl
void * memcpy( void * _PDCLIB_restrict s1, const void * _PDCLIB_restrict s2, size_t n )
{
assert( s1 < s2 ? s1 + n <= s2 : s2 + n <= s1 );
- return memmove( s1, (void *)s2, n );
+
+ char *dst = ( char * ) s1;
+ const char *src = ( const char * ) s2;
+
+ switch ( n )
+ {
+ case 1: *dst = *src; return s1;
+ case 2: *( uint16_t * ) dst = *( uint16_t * ) src; return s1;
+ case 4: *( uint32_t * ) dst = *( uint32_t * ) src; return s1;
+ case 8: *( uint64_t * ) dst = *( uint64_t * ) src; return s1;
+ default:
+ {
+ while ( ( uint64_t ) dst % 8 && ( uint64_t ) src % 8 && n )
+ *dst++ = *src++, n --;
+
+ uint64_t *src_l = ( uint64_t * ) src;
+ uint64_t *dst_l = ( uint64_t * ) dst;
+
+ while ( n >= 8 )
+ {
+ *dst_l++ = *src_l++;
+ n -= 8;
+ }
+
+ src = ( const char * ) src_l;
+ dst = ( char *) dst_l;
+ while ( n-- )
+ *dst++ = *src++;
+ }
+ return s1;
+ }
}
#endif
--
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