* [musl] Re: [Patch 1/1] vfprintf: optimize vfprintf performance
@ 2023-06-12 7:56 =?gb18030?B?ODQ3NTY3MTYx?=
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From: =?gb18030?B?ODQ3NTY3MTYx?= @ 2023-06-12 7:56 UTC (permalink / raw)
To: =?gb18030?B?bXVzbA==?=
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Hi all£¬
How about the patch sent in May£¿I can modify it if there are any problem.
the benchmark show there are about 30% benefits for commonly used format string.
before opt: 160ns
after opt: 110ns
static void BM_stdio_printf_s(benchmark::State& state) {
while (state.KeepRunning()) {
char buf[BUFSIZ];
snprintf(buf, sizeof(buf), "this is a more typical error message with detail: %s",
"No such file or directory");
}
}
MUSL_BENCHMARK(BM_stdio_printf_s);
Chuang Yin
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diff --git a/src/stdio/vfprintf.c b/src/stdio/vfprintf.c
index 9b961e7f..4a01ca1e 100644
--- a/src/stdio/vfprintf.c
+++ b/src/stdio/vfprintf.c
@@ -427,7 +427,7 @@ static int getint(char **s) {
return i;
}
-static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg, int *nl_type)
+static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg, int *nl_type, char nl_arg_filled)
{
char *a, *z, *s=(char *)fmt;
unsigned l10n=0, fl;
@@ -437,7 +437,6 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
unsigned st, ps;
int cnt=0, l=0;
size_t i;
- char buf[sizeof(uintmax_t)*3+3+LDBL_MANT_DIG/4];
const char *prefix;
int t, pl;
wchar_t wc[2], *ws;
@@ -462,6 +461,11 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
if (l) continue;
if (isdigit(s[1]) && s[2]=='$') {
+ if (!nl_arg_filled) {
+ if (printf_core(0, fmt, ap, nl_arg, nl_type, 1) < 0) {
+ return -1;
+ }
+ }
l10n=1;
argpos = s[1]-'0';
s+=3;
@@ -528,6 +532,7 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
if (!f) continue;
+ char buf[sizeof(uintmax_t)*3+3+LDBL_MANT_DIG/4];
z = buf + sizeof(buf);
prefix = "-+ 0X0x";
pl = 0;
@@ -665,10 +670,6 @@ int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)
/* the copy allows passing va_list* even if va_list is an array */
va_copy(ap2, ap);
- if (printf_core(0, fmt, &ap2, nl_arg, nl_type) < 0) {
- va_end(ap2);
- return -1;
- }
FLOCK(f);
olderr = f->flags & F_ERR;
@@ -680,7 +681,7 @@ int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)
f->wpos = f->wbase = f->wend = 0;
}
if (!f->wend && __towrite(f)) ret = -1;
- else ret = printf_core(f, fmt, &ap2, nl_arg, nl_type);
+ else ret = printf_core(f, fmt, &ap2, nl_arg, nl_type, 0);
if (saved_buf) {
f->write(f, 0, 0);
if (!f->wpos) ret = -1;
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2023-06-12 7:56 [musl] Re: [Patch 1/1] vfprintf: optimize vfprintf performance =?gb18030?B?ODQ3NTY3MTYx?=
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