musl - Re: [Patch 1/1] vfprintf: optimize vfprintf performance

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Date: Mon, 15 May 2023 10:31:38 +0200
From: Quentin Rameau <quinq@...th.space>
To: musl@...ts.openwall.com
Subject: Re: [Patch 1/1] vfprintf: optimize vfprintf performance

Hi 847567161

> I made a patch to get&nbsp;nl_arg when we see '$' ranther than visit the format anyway，could you please help me review it？
> 
> diff --git a/src/stdio/vfprintf.c b/src/stdio/vfprintf.c old mode 100644 new mode 100755 index 9b961e7f..3294e23b --- a/src/stdio/vfprintf.c +++ b/src/stdio/vfprintf.c @@ -427,7 +427,7 @@ static int getint(char **s) {  	return i;  }   -static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg, int *nl_type) +static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg, int *nl_type, union arg* nl_arg_ptr)  {  	char *a, *z, *s=(char *)fmt;  	unsigned l10n=0, fl; @@ -462,6 +462,12 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,  		if (l) continue;    		if (isdigit(s[1]) &amp;&amp; s[2]=='$') { +			if (nl_arg_ptr == NULL) { +				nl_arg_ptr = nl_arg; +				if (printf_core(0, fmt, ap, nl_arg, nl_type, nl_arg_ptr) < 0) { +					return -1; +				} +			}  			l10n=1;  			argpos = s[1]-'0';  			s+=3; @@ -477,6 +483,12 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,  		/* Read field width */  		if (*s=='*') {  			if (isdigit(s[1]) &amp;&amp; s[2]=='$') { +				if (nl_arg_ptr == NULL) { +					nl_arg_ptr = nl_arg; +					if (printf_core(0, fmt, ap, nl_arg, nl_type, nl_arg_ptr) < 0) { +						return -1; +					} +				}  				l10n=1;  				nl_type[s[1]-'0'] = INT;  				w = nl_arg[s[1]-'0'].i; @@ -491,6 +503,12 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,  		/* Read precision */  		if (*s=='.' &amp;&amp; s[1]=='*') {  			if (isdigit(s[2]) &amp;&amp; s[3]=='$') { +				if (nl_arg_ptr == NULL) { +					nl_arg_ptr = nl_arg; +					if (printf_core(0, fmt, ap, nl_arg, nl_type, nl_arg_ptr) < 0) { +						return -1; +					} +				}  				nl_type[s[2]-'0'] = INT;  				p = nl_arg[s[2]-'0'].i;  				s+=4; @@ -659,16 +677,13 @@ int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)  	va_list ap2;  	int nl_type[NL_ARGMAX+1] = {0};  	union arg nl_arg[NL_ARGMAX+1]; +	union arg* nl_arg_ptr = NULL;  	unsigned char internal_buf[80], *saved_buf = 0;  	int olderr;  	int ret;    	/* the copy allows passing va_list* even if va_list is an array */  	va_copy(ap2, ap); -	if (printf_core(0, fmt, &amp;ap2, nl_arg, nl_type) < 0) { -		va_end(ap2); -		return -1; -	}    	FLOCK(f);  	olderr = f-&gt;flags &amp; F_ERR; @@ -680,7 +695,7 @@ int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)  		f-&gt;wpos = f-&gt;wbase = f-&gt;wend = 0;  	}  	if (!f-&gt;wend &amp;&amp; __towrite(f)) ret = -1; -	else ret = printf_core(f, fmt, &amp;ap2, nl_arg, nl_type); +	else ret = printf_core(f, fmt, &amp;ap2, nl_arg, nl_type, nl_arg_ptr);  	if (saved_buf) {  		f-&gt;write(f, 0, 0);  		if (!f-&gt;wpos) ret = -1;

Could you try sending it in a more readable way?
One way would be to commit the diff and sending it with git-send-email
but attaching a diff file, or simply inlining the patch as plain-text
would also work.

Thank you!
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