[Skiboot] [PATCH 09/11] Optimize memset() implementation to do word at a time

[Stewart Smith]

Makes booting with gcov enabled take dozens of seconds faster

Signed-off-by: Stewart Smith <stewart at linux.vnet.ibm.com>
---
 libc/string/memset.c        |   15 ++++++++++++++-
 libc/test/run-memops-test.c |   16 ++++++++++++++++
 libc/test/run-memops.c      |    3 +++
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/libc/string/memset.c b/libc/string/memset.c
index f8dfbf5..e7172b0 100644
--- a/libc/string/memset.c
+++ b/libc/string/memset.c
@@ -15,7 +15,20 @@
 void *
 memset(void *dest, int c, size_t size)
 {
-	unsigned char *d = (unsigned char *)dest;
+	unsigned char *d;
+	unsigned long long *d64 = (unsigned long long*)dest;
+	unsigned long long c8 = c;
+
+	if (size > 8) {
+		c8 = c8 | c8 << 8ULL | c8 << 16ULL | c8 << 24ULL | c8 << 32ULL
+			| c8 << 40ULL | c8 << 48ULL | c8 << 56ULL;
+		while (size > 8) {
+			*d64++ = c8;
+			size = size - 8;
+		}
+	}
+
+	d = (unsigned char *)d64;
 
 	while (size-- > 0) {
 		*d++ = (unsigned char)c;
diff --git a/libc/test/run-memops-test.c b/libc/test/run-memops-test.c
index 0979994..6ec5a27 100644
--- a/libc/test/run-memops-test.c
+++ b/libc/test/run-memops-test.c
@@ -41,3 +41,19 @@
 #include "../string/strncpy.c"
 #include "../string/strstr.c"
 #include "../string/strtok.c"
+
+char buf[100];
+
+int test_memset(void);
+
+int test_memset(void)
+{
+	int i;
+	int r= 0;
+
+	memset(buf, 0x42, sizeof(buf));
+	for(i=0; i<sizeof(buf); i++)
+		if (buf[i] != 0x42)
+			r = -1;
+	return r;
+}
diff --git a/libc/test/run-memops.c b/libc/test/run-memops.c
index 15ec9bd..7158b6b 100644
--- a/libc/test/run-memops.c
+++ b/libc/test/run-memops.c
@@ -21,7 +21,10 @@
 #include <string.h>
 #include <stdio.h>
 
+int test_memset(void);
+
 int main(void)
 {
+	assert(test_memset() == 0);
 	return 0;
 }
-- 
1.7.10.4