Date: Tue, 11 May 2021 10:31:08 GMT From: Alex Richardson <arichardson@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: fc19e3cb4fd1 - stable/13 - libc/string/memset.c: Use unsigned long for stores Message-ID: <202105111031.14BAV8f0085663@gitrepo.freebsd.org>
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The branch stable/13 has been updated by arichardson: URL: https://cgit.FreeBSD.org/src/commit/?id=fc19e3cb4fd1403a6c6dba3c9879db031faa9df3 commit fc19e3cb4fd1403a6c6dba3c9879db031faa9df3 Author: Alex Richardson <arichardson@FreeBSD.org> AuthorDate: 2021-04-19 23:19:20 +0000 Commit: Alex Richardson <arichardson@FreeBSD.org> CommitDate: 2021-05-11 08:39:27 +0000 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 (cherry picked from commit ab147542b7c0bbc41f7f0499b16933bd8f3f31d7) --- lib/libc/string/memset.c | 19 +++++++++++-------- 1 file 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);
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