6g: generate string data as individual symbols,

so that 6l can discard strings used by dead code.
also, for short strings, generate DUPOK global
symbols so that references to, say, "%s: %s" in
multiple files result in only a single symbol.

R=ken
OCL=28361
CL=28361

src/cmd/6g/gg.h

@@ -122,6 +122,7 @@ int	isfat(Type*);
 void	sudoclean(void);
 int	sudoaddable(int, Node*, Addr*);
 void	afunclit(Addr*);
+void	datagostring(Strlit*, Addr*);
 
 /*
  * list.c

src/cmd/6g/gsubr.c

@@ -152,8 +152,6 @@ ggloblsym(Sym *s, int32 width, int dupok)
 
 	p = gins(AGLOBL, N, N);
 	p->from.type = D_EXTERN;
-	if(s == symstringl || s == symstringc)
-		p->from.type = D_STATIC;
 	p->from.index = D_NONE;
 	p->from.sym = s;
 	p->to.type = D_CONST;
@@ -1146,11 +1144,7 @@ naddr(Node *n, Addr *a)
 			a->offset = mpgetfix(n->val.u.xval);
 			break;
 		case CTSTR:
-			a->etype = simtype[n->etype];
-			a->sym = symstringl;
-			a->type = D_STATIC;
-			a->offset = symstringl->offset;
-			stringpool(n);
+			datagostring(n->val.u.sval, a);
 			break;
 		case CTBOOL:
 			a->sym = S;

src/cmd/6g/obj.c

@@ -261,23 +261,75 @@ dumpfuncs(void)
 	}
 }
 
+/* deferred DATA output */
+static Prog *strdat;
+static Prog *estrdat;
+static int gflag;
+static Prog *savepc;
+
+static void
+data(void)
+{
+	gflag = debug['g'];
+	debug['g'] = 0;
+	
+	if(estrdat == nil) {
+		strdat = mal(sizeof(*pc));
+		clearp(strdat);
+		estrdat = strdat;
+	}
+	if(savepc)
+		fatal("data phase error");
+	savepc = pc;
+	pc = estrdat;
+}
+
+static void
+text(void)
+{
+	if(!savepc)
+		fatal("text phase error");
+	debug['g'] = gflag;
+	estrdat = pc;
+	pc = savepc;
+	savepc = nil;
+}
+
+void
+dumpdata(void)
+{
+	Prog *p;
+
+	if(estrdat == nil)
+		return;
+	*pc = *strdat;
+	if(gflag)
+		for(p=pc; p!=estrdat; p=p->link)
+			print("%P\n", p);
+	pc = estrdat;
+}
+
 /*
- * dump the characters of the string
- * pool into the array symstringc
+ * make a refer to the data s, s+len
+ * emitting DATA if needed.
  */
 void
-datastring(char *s, int len)
+datastring(char *s, int len, Addr *a)
 {
 	int w;
 	Prog *p;
 	Addr ac, ao;
-
+	static int gen;
+	struct {
+		Strlit lit;
+		char buf[100];
+	} tmp;
+	
 	// string
 	memset(&ao, 0, sizeof(ao));
 	ao.type = D_STATIC;
 	ao.index = D_NONE;
 	ao.etype = TINT32;
-	ao.sym = symstringc;
 	ao.offset = 0;		// fill in
 
 	// constant
@@ -286,13 +338,37 @@ datastring(char *s, int len)
 	ac.index = D_NONE;
 	ac.offset = 0;		// fill in
 
+	// huge strings are made static to avoid long names.
+	if(len > 100) {
+		snprint(namebuf, sizeof(namebuf), ".string.%d", gen++);
+		ao.sym = lookup(namebuf);
+		ao.type = D_STATIC;
+	} else {
+		if(len > 0 && s[len-1] == '\0')
+			len--;
+		tmp.lit.len = len;
+		memmove(tmp.lit.s, s, len);
+		tmp.lit.s[len] = '\0';
+		len++;
+		snprint(namebuf, sizeof(namebuf), "\"%Z\"", &tmp.lit);
+		ao.sym = pkglookup(namebuf, "string");
+		ao.type = D_EXTERN;
+	}
+	*a = ao;
+
+	// only generate data the first time.
+	if(ao.sym->uniq)
+		return;
+	ao.sym->uniq = 1;
+
+	data();
 	for(w=0; w<len; w+=8) {
 		p = pc;
 		gins(ADATA, N, N);
 
-		// .stringo<>+oo, [NSNAME], $"xxx"
+		// DATA s+w, [NSNAME], $"xxx"
 		p->from = ao;
-		p->from.offset = stringc;
+		p->from.offset = w;
 
 		p->from.scale = NSNAME;
 		if(w+8 > len)
@@ -302,25 +378,25 @@ datastring(char *s, int len)
 		p->to.type = D_SCONST;
 		p->to.offset = len;
 		memmove(p->to.sval, s+w, p->from.scale);
-		stringc += p->from.scale;
 	}
+	p = pc;
+	ggloblsym(ao.sym, len, ao.type == D_EXTERN);
+	if(ao.type == D_STATIC)
+		p->from.type = D_STATIC;
+	text();
 }
 
 /*
- * dump the strings into thye pool
- * symstingl that consists of a pointer
- * to the characters and a count
+ * make a refer to the string sval,
+ * emitting DATA if needed.
  */
 void
-dumpstrings(void)
+datagostring(Strlit *sval, Addr *a)
 {
-	Pool *l;
 	Prog *p;
 	Addr ac, ao, ap;
-	int32 wi, wp, ws;
-
-	if(poolist == nil)
-		return;
+	int32 wi, wp;
+	static int gen;
 
 	memset(&ac, 0, sizeof(ac));
 	memset(&ao, 0, sizeof(ao));
@@ -332,49 +408,61 @@ dumpstrings(void)
 	ac.offset = 0;			// fill in
 
 	// string len+ptr
-	ao.type = D_STATIC;
+	ao.type = D_STATIC;		// fill in
 	ao.index = D_NONE;
 	ao.etype = TINT32;
-	ao.sym = symstringl;
-	ao.offset = 0;			// fill in
+	ao.sym = nil;			// fill in
 
 	// $string len+ptr
+	datastring(sval->s, sval->len, &ap);
+	ap.index = ap.type;
 	ap.type = D_ADDR;
-	ap.index = D_STATIC;
 	ap.etype = TINT32;
-	ap.sym = symstringc;
-	ap.offset = 0;			// fill in
 
 	wi = types[TUINT32]->width;
 	wp = types[tptr]->width;
-	ws = types[TSTRING]->width;
-
-	// lay out (count+string)
-	for(l=poolist; l!=nil; l=l->link) {
+	
+	if(ap.index == D_STATIC) {
+		// huge strings are made static to avoid long names
+		snprint(namebuf, sizeof(namebuf), ".gostring.%d", ++gen);
+		ao.sym = lookup(namebuf);
+		ao.type = D_STATIC;
+	} else {
+		// small strings get named by their contents,
+		// so that multiple modules using the same string
+		// can share it.
+		snprint(namebuf, sizeof(namebuf), "\"%Z\"", sval);
+		ao.sym = pkglookup(namebuf, "go.string");
+		ao.type = D_EXTERN;
+	}
 
-		// .stringl<>+ol, wp, $.stringc<>+oc
-		p = pc;
-		gins(ADATA, N, N);
-		p->from = ao;
-		p->from.offset = stringl;
-		p->from.scale = wp;
-		p->to = ap;
-		p->to.offset = stringc;
-		stringl += wp;
+	*a = ao;
+	if(ao.sym->uniq)
+		return;
+	ao.sym->uniq = 1;
 
-		// .stringl<>+ol, wi, $len
-		p = pc;
-		gins(ADATA, N, N);
-		p->from = ao;
-		p->from.offset = stringl;
-		p->from.scale = wi;
-		p->to = ac;
-		p->to.offset = l->sval->len;
-		stringl += wi;
+	data();
+	// DATA gostring, wp, $cstring
+	p = pc;
+	gins(ADATA, N, N);
+	p->from = ao;
+	p->from.scale = wp;
+	p->to = ap;
 
-		stringl = rnd(stringl, ws);
-		datastring(l->sval->s, l->sval->len);
-	}
+	// DATA gostring+wp, wi, $len
+	p = pc;
+	gins(ADATA, N, N);
+	p->from = ao;
+	p->from.offset = wp;
+	p->from.scale = wi;
+	p->to = ac;
+	p->to.offset = sval->len;
+	
+	p = pc;
+	ggloblsym(ao.sym, types[TSTRING]->width, ao.type == D_EXTERN);
+	if(ao.type == D_STATIC)
+		p->from.type = D_STATIC;
+	text();
 }
 
 int
@@ -390,14 +478,12 @@ dstringptr(Sym *s, int off, char *str)
 	p->from.offset = off;
 	p->from.scale = widthptr;
 
+	datastring(str, strlen(str)+1, &p->to);
+	p->to.index = p->to.type;
 	p->to.type = D_ADDR;
-	p->to.index = D_STATIC;
 	p->to.etype = TINT32;
-	p->to.sym = symstringc;
-	p->to.offset = stringc;
 	off += widthptr;
 
-	datastring(str, strlen(str)+1);
 	return off;
 }
 

src/cmd/gc/go.h

@@ -463,20 +463,6 @@ struct Sig
 	Sig*	link;
 };
 
-typedef	struct	Pool Pool;
-struct	Pool
-{
-	Strlit*	sval;
-	Pool*	link;
-};
-
-EXTERN	Pool*	poolist;
-EXTERN	Pool*	poolast;
-EXTERN	Sym*	symstringl;	// string literals
-EXTERN	Sym*	symstringc;	// string characters
-EXTERN	int32	stringl;	// size of string literals
-EXTERN	int32	stringc;	// size of string characters
-
 typedef	struct	Io	Io;
 struct	Io
 {
@@ -785,7 +771,6 @@ int	brrev(int);
 void	setmaxarg(Type*);
 Sig*	lsort(Sig*, int(*)(Sig*, Sig*));
 int	dotoffset(Node*, int*, Node**);
-void	stringpool(Node*);
 void	tempname(Node*, Type*);
 
 int	Econv(Fmt*);
@@ -1029,7 +1014,6 @@ Plist*	newplist(void);
  *	obj.c
  */
 void	Bputdot(Biobuf *b);
-void	dumpfuncs(void);
 void	dumpglobls(void);
 void	dumpobj(void);
 void	ieeedtod(uint64 *ieee, double native);
@@ -1060,17 +1044,15 @@ int	isfat(Type*);
 void	clearfat(Node *n);
 void	cgen(Node*, Node*);
 void	gused(Node*);
-void	dumpstrings(void);
 void	dumpsignatures(void);
 void	dumpfuncs(void);
+void	dumpdata(void);
 void	ggloblnod(Node *nam, int32 width);
 void	ggloblsym(Sym *s, int32 width, int dupok);
 void	zfile(Biobuf *b, char *p, int n);
 void	zhist(Biobuf *b, int line, vlong offset);
 void	zname(Biobuf *b, Sym *s, int t);
-void	dumpstrings(void);
 void	nopout(Prog*);
-void	datastring(char *s, int len);
 int	dstringptr(Sym *s, int off, char *str);
 int	dsymptr(Sym *s, int off, Sym *x);
 int	duint16(Sym *s, int off, uint32 v);

src/cmd/gc/lex.c

@@ -66,9 +66,6 @@ main(int argc, char *argv[])
 	lexinit();
 	typeinit(LBASETYPE);
 
-	symstringl = lookup(".stringl");	// string literals (ptr to char and count)
-	symstringc = lookup(".stringc");	// string characters
-
 	lineno = 1;
 	block = 1;
 	blockgen = 1;

src/cmd/gc/obj.c

@@ -28,8 +28,8 @@ dumpobj(void)
 	newplist();
 
 	dumpglobls();
-	dumpstrings();
 	dumpsignatures();
+	dumpdata();
 	dumpfuncs();
 
 	Bterm(bout);
@@ -483,42 +483,6 @@ dumpsignatures(void)
 //print("s=%S\n", s);
 		dumpsigt(progt, ifacet, rcvrt, methodt, s);
 	}
-
-	if(stringl > 0) {
-		stringl = rnd(stringl, maxround);
-		ggloblsym(symstringl, stringl, 0);
-		if(stringc == 0)
-			stringc = 1;
-	}
-	if(stringc > 0) {
-		stringc = rnd(stringc, maxround);
-		ggloblsym(symstringc, stringc, 0);
-	}
-}
-
-void
-stringpool(Node *n)
-{
-	Pool *p;
-
-	if(n->op != OLITERAL || n->val.ctype != CTSTR) {
-		if(n->val.ctype == CTNIL)
-			return;
-		fatal("stringpool: not string %N", n);
-	}
-
-	p = mal(sizeof(*p));
-
-	p->sval = n->val.u.sval;
-	p->link = nil;
-
-	if(poolist == nil)
-		poolist = p;
-	else
-		poolast->link = p;
-	poolast = p;
-
-	symstringl->offset += types[TSTRING]->width;
 }
 
 Sig*