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author | Alex Richardson <arichardson@FreeBSD.org> | 2021-04-19 23:19:20 +0000 |
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committer | Alex Richardson <arichardson@FreeBSD.org> | 2021-04-20 00:46:43 +0000 |
commit | ab147542b7c0bbc41f7f0499b16933bd8f3f31d7 (patch) | |
tree | f437b834675d59616178d9b67a3337b779f5407f | |
parent | 0b4ad01d91a3b24cea00d54d25beed0f487c0183 (diff) | |
download | src-ab147542b7c0bbc41f7f0499b16933bd8f3f31d7.tar.gz src-ab147542b7c0bbc41f7f0499b16933bd8f3f31d7.zip |
libc/string/memset.c: Use unsigned long for stores
While most 64-bit architectures have an assembly implementation of this
file, RISC-V does not. As we now store 8 bytes instead of 4 it should speed
up RISC-V.
Reviewed By: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D29536
-rw-r--r-- | lib/libc/string/memset.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/lib/libc/string/memset.c b/lib/libc/string/memset.c index 7d9909a76083..e2d4027eea0c 100644 --- a/lib/libc/string/memset.c +++ b/lib/libc/string/memset.c @@ -42,7 +42,7 @@ __FBSDID("$FreeBSD$"); #include <limits.h> -#define wsize sizeof(u_int) +#define wsize sizeof(u_long) #define wmask (wsize - 1) #ifdef BZERO @@ -67,7 +67,7 @@ memset(void *dst0, int c0, size_t length) { size_t t; #ifndef BZERO - u_int c; + u_long c; #endif u_char *dst; @@ -84,6 +84,9 @@ memset(void *dst0, int c0, size_t length) * * but we use a minimum of 3 here since the overhead of the code * to do word writes is substantial. + * + * TODO: This threshold might not be sensible for 64-bit u_long. + * We should benchmark and revisit this decision. */ if (length < 3 * wsize) { while (length != 0) { @@ -95,12 +98,12 @@ memset(void *dst0, int c0, size_t length) #ifndef BZERO if ((c = (u_char)c0) != 0) { /* Fill the word. */ - c = (c << 8) | c; /* u_int is 16 bits. */ -#if UINT_MAX > 0xffff - c = (c << 16) | c; /* u_int is 32 bits. */ + c = (c << 8) | c; /* u_long is 16 bits. */ +#if ULONG_MAX > 0xffff + c = (c << 16) | c; /* u_long is 32 bits. */ #endif -#if UINT_MAX > 0xffffffff - c = (c << 32) | c; /* u_int is 64 bits. */ +#if ULONG_MAX > 0xffffffff + c = (c << 32) | c; /* u_long is 64 bits. */ #endif } #endif @@ -116,7 +119,7 @@ memset(void *dst0, int c0, size_t length) /* Fill words. Length was >= 2*words so we know t >= 1 here. */ t = length / wsize; do { - *(u_int *)dst = WIDEVAL; + *(u_long *)(void *)dst = WIDEVAL; dst += wsize; } while (--t != 0); |