runtime: avoid allocation for fixed strings

R=r
CC=golang-dev
https://golang.org/cl/1083041

src/pkg/runtime/darwin/386/signal.c

@@ -30,7 +30,7 @@ signame(int32 sig)
 {
 	if(sig < 0 || sig >= NSIG)
 		return emptystring;
-	return gostring((byte*)sigtab[sig].name);
+	return gostringnocopy((byte*)sigtab[sig].name);
 }
 
 void

src/pkg/runtime/darwin/amd64/signal.c

@@ -38,7 +38,7 @@ signame(int32 sig)
 {
 	if(sig < 0 || sig >= NSIG)
 		return emptystring;
-	return gostring((byte*)sigtab[sig].name);
+	return gostringnocopy((byte*)sigtab[sig].name);
 }
 
 void

src/pkg/runtime/freebsd/386/signal.c

@@ -41,7 +41,7 @@ signame(int32 sig)
 {
 	if(sig < 0 || sig >= NSIG)
 		return emptystring;
-	return gostring((byte*)sigtab[sig].name);
+	return gostringnocopy((byte*)sigtab[sig].name);
 }
 
 void

src/pkg/runtime/freebsd/amd64/signal.c

@@ -49,7 +49,7 @@ signame(int32 sig)
 {
 	if(sig < 0 || sig >= NSIG)
 		return emptystring;
-	return gostring((byte*)sigtab[sig].name);
+	return gostringnocopy((byte*)sigtab[sig].name);
 }
 
 void

src/pkg/runtime/iface.c

@@ -467,7 +467,7 @@ ifacehash1(void *data, Type *t)
 	if(algarray[alg].hash == nohash) {
 		// calling nohash will panic too,
 		// but we can print a better error.
-		·newErrorString(catstring(gostring((byte*)"hash of unhashable type "), *t->string), &err);
+		·newErrorString(catstring(gostringnocopy((byte*)"hash of unhashable type "), *t->string), &err);
 		·panic(err);
 	}
 	if(wid <= sizeof(data))
@@ -501,7 +501,7 @@ ifaceeq1(void *data1, void *data2, Type *t)
 	if(algarray[alg].equal == noequal) {
 		// calling noequal will panic too,
 		// but we can print a better error.
-		·newErrorString(catstring(gostring((byte*)"comparing uncomparable type "), *t->string), &err);
+		·newErrorString(catstring(gostringnocopy((byte*)"comparing uncomparable type "), *t->string), &err);
 		·panic(err);
 	}
 

src/pkg/runtime/linux/386/signal.c

@@ -38,7 +38,7 @@ signame(int32 sig)
 {
 	if(sig < 0 || sig >= NSIG)
 		return emptystring;
-	return gostring((byte*)sigtab[sig].name);
+	return gostringnocopy((byte*)sigtab[sig].name);
 }
 
 void

src/pkg/runtime/linux/amd64/signal.c

@@ -46,7 +46,7 @@ signame(int32 sig)
 {
 	if(sig < 0 || sig >= NSIG)
 		return emptystring;
-	return gostring((byte*)sigtab[sig].name);
+	return gostringnocopy((byte*)sigtab[sig].name);
 }
 
 void

src/pkg/runtime/linux/arm/signal.c

@@ -46,7 +46,7 @@ signame(int32 sig)
 {
 	if(sig < 0 || sig >= NSIG)
 		return emptystring;
-	return gostring((byte*)sigtab[sig].name);
+	return gostringnocopy((byte*)sigtab[sig].name);
 }
 
 void

src/pkg/runtime/runtime.c

@@ -79,7 +79,7 @@ panicstring(int8 *s)
 {
 	Eface err;
 	
-	·newErrorString(gostring((byte*)s), &err);
+	·newErrorString(gostringnocopy((byte*)s), &err);
 	·panic(err);
 }
 
@@ -161,13 +161,13 @@ goargs(void)
 	genvv = malloc(envc*sizeof genvv[0]);
 
 	for(i=0; i<argc; i++)
-		gargv[i] = gostring(argv[i]);
+		gargv[i] = gostringnocopy(argv[i]);
 	os·Args.array = (byte*)gargv;
 	os·Args.len = argc;
 	os·Args.cap = argc;
 
 	for(i=0; i<envc; i++)
-		genvv[i] = gostring(argv[argc+1+i]);
+		genvv[i] = gostringnocopy(argv[argc+1+i]);
 	os·Envs.array = (byte*)genvv;
 	os·Envs.len = envc;
 	os·Envs.cap = envc;
@@ -220,7 +220,7 @@ void
 	byte *p;
 
 	p = getenv("GOROOT");
-	out = gostring(p);
+	out = gostringnocopy(p);
 	FLUSH(&out);
 }
 

src/pkg/runtime/runtime.h

@@ -387,6 +387,7 @@ void*	mal(uintptr);
 uint32	cmpstring(String, String);
 String	catstring(String, String);
 String	gostring(byte*);
+String	gostringnocopy(byte*);
 String	gostringw(uint16*);
 void	initsig(void);
 int32	gotraceback(void);

src/pkg/runtime/string.goc

@@ -60,6 +60,16 @@ gostring(byte *str)
 	return s;
 }
 
+String
+gostringnocopy(byte *str)
+{
+	String s;
+	
+	s.str = str;
+	s.len = findnull(str);
+	return s;
+}
+
 String
 gostringw(uint16 *str)
 {

src/pkg/runtime/symtab.c

@@ -106,7 +106,7 @@ dofunc(Sym *sym)
 			break;
 		}
 		f = &func[nfunc++];
-		f->name = gostring(sym->name);
+		f->name = gostringnocopy(sym->name);
 		f->entry = sym->value;
 		if(sym->symtype == 'L' || sym->symtype == 'l')
 			f->frame = -sizeof(uintptr);