From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Sun, 29 Jan 2012 21:38:35 +0000 (+0100)
Subject: Simple optimizations
X-Git-Tag: v4.7~181
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4f3df078b26899afe0f25d8651b06a5a5b5143e2;p=strace

Simple optimizations

   text	   data	    bss	    dec	    hex	filename
 239474	    672	  20484	 260630	  3fa16	strace.before
 239234	    668	  19044	 258946	  3f382	strace

* file.c (sprint_open_modes): Reduce static buffer size.
Simplify separator printing.
* signal.c (sprintsigmask): Reduce static buffer size.
Simplify separator printing and printing of almost full masks.
Use stpcpy instead of sprintf and strcpy+strlen.
* strace.c (startup_child): Don't strchr() for ':' twice in a row.
* util.c (sprintflags): Exit loop early if possible.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---

diff --git a/file.c b/file.c
index b2567c5b..87e07438 100644
--- a/file.c
+++ b/file.c
@@ -272,7 +272,6 @@ const struct xlat open_mode_flags[] = {
 #ifdef O_CLOEXEC
 	{ O_CLOEXEC,	"O_CLOEXEC"	},
 #endif
-
 #ifdef FNDELAY
 	{ FNDELAY,	"FNDELAY"	},
 #endif
@@ -349,15 +348,17 @@ print_dirfd(struct tcb *tcp, int fd)
 const char *
 sprint_open_modes(mode_t flags)
 {
-	static char outstr[1024];
+	static char outstr[(1 + ARRAY_SIZE(open_mode_flags)) * sizeof("O_LARGEFILE")];
 	char *p;
-	char sep = 0;
+	char sep;
 	const char *str;
 	const struct xlat *x;
 
-	p = stpcpy(outstr, "flags ");
+	sep = ' ';
+	p = stpcpy(outstr, "flags");
 	str = xlookup(open_access_modes, flags & 3);
 	if (str) {
+		*p++ = sep;
 		p = stpcpy(p, str);
 		flags &= ~3;
 		if (!flags)
@@ -367,8 +368,7 @@ sprint_open_modes(mode_t flags)
 
 	for (x = open_mode_flags; x->str; x++) {
 		if ((flags & x->val) == x->val) {
-			if (sep)
-				*p++ = sep;
+			*p++ = sep;
 			p = stpcpy(p, x->str);
 			flags &= ~x->val;
 			if (!flags)
@@ -377,8 +377,7 @@ sprint_open_modes(mode_t flags)
 		}
 	}
 	/* flags is still nonzero */
-	if (sep)
-		*p++ = sep;
+	*p++ = sep;
 	sprintf(p, "%#x", flags);
 	return outstr;
 }
diff --git a/signal.c b/signal.c
index aca6345f..4556a5fe 100644
--- a/signal.c
+++ b/signal.c
@@ -319,64 +319,57 @@ sprintsigmask(const char *str, sigset_t *mask, int rt)
 	 * and sig 0 doesn't exist either.
 	 * Therefore max possible no of sigs is 255: 1..255
 	 */
-	static char outstr[8 * 255];
+	static char outstr[8 * (255 * 2 / 3)];
 
 	int i, nsigs;
 	int maxsigs;
-	const char *format;
+	int show_members;
+	char sep;
 	char *s;
 
-	strcpy(outstr, str);
-	s = outstr + strlen(outstr);
-	nsigs = 0;
 	maxsigs = nsignals;
 #ifdef __SIGRTMAX
 	if (rt)
 		maxsigs = __SIGRTMAX; /* instead */
 #endif
+	s = stpcpy(outstr, str);
+	nsigs = 0;
 	for (i = 1; i < maxsigs; i++) {
 		if (sigismember(mask, i) == 1)
 			nsigs++;
 	}
-	if (nsigs >= nsignals * 2 / 3) {
+
+	/* 1: show mask members, 0: show those which are NOT in mask */
+	show_members = (nsigs < nsignals * 2 / 3);
+	if (!show_members)
 		*s++ = '~';
-		for (i = 1; i < maxsigs; i++) {
-			switch (sigismember(mask, i)) {
-			case 1:
-				sigdelset(mask, i);
-				break;
-			case 0:
-				sigaddset(mask, i);
-				break;
-			}
-		}
-	}
-	format = "%s";
-	*s++ = '[';
+
+	sep = '[';
 	for (i = 1; i < maxsigs; i++) {
-		if (sigismember(mask, i) == 1) {
+		if (sigismember(mask, i) == show_members) {
 			/* real-time signals on solaris don't have
 			 * signalent entries
 			 */
+			char tsig[40];
+			*s++ = sep;
 			if (i < nsignals) {
-				sprintf(s, format, signalent[i] + 3);
+				s = stpcpy(s, signalent[i] + 3);
 			}
 #ifdef SIGRTMIN
 			else if (i >= __SIGRTMIN && i <= __SIGRTMAX) {
-				char tsig[40];
 				sprintf(tsig, "RT_%u", i - __SIGRTMIN);
-				sprintf(s, format, tsig);
+				s = stpcpy(s, tsig);
 			}
 #endif /* SIGRTMIN */
 			else {
-				char tsig[32];
 				sprintf(tsig, "%u", i);
-				sprintf(s, format, tsig);
+				s = stpcpy(s, tsig);
 			}
-			s += strlen(s);
-			format = " %s";
+			sep = ' ';
 		}
 	}
+	if (sep == '[')
+		*s++ = sep;
 	*s++ = ']';
 	*s = '\0';
 	return outstr;
diff --git a/strace.c b/strace.c
index b739cd62..38c8518a 100644
--- a/strace.c
+++ b/strace.c
@@ -656,8 +656,9 @@ startup_child(char **argv)
 		int m, n, len;
 
 		for (path = getenv("PATH"); path && *path; path += m) {
-			if (strchr(path, ':')) {
-				n = strchr(path, ':') - path;
+			const char *colon = strchr(path, ':');
+			if (colon) {
+				n = colon - path;
 				m = n + 1;
 			}
 			else
diff --git a/util.c b/util.c
index 2a73db78..b6cdf9a5 100644
--- a/util.c
+++ b/util.c
@@ -325,8 +325,10 @@ sprintflags(const char *prefix, const struct xlat *xlat, int flags)
 			if (found)
 				*outptr++ = '|';
 			outptr = stpcpy(outptr, xlat->str);
-			flags &= ~xlat->val;
 			found = 1;
+			flags &= ~xlat->val;
+			if (!flags)
+				break;
 		}
 	}
 	if (flags) {