ld: 25% faster

The ld time was dominated by symbol table processing, so
  * increase hash table size
  * emit fewer symbols in gc (just 1 per string, 1 per type)
  * add read-only lookup to avoid creating spurious symbols
  * add linked list to speed whole-table traversals

Breaks dwarf generator (no idea why), so disable dwarf.

Reduces time for 6l to link godoc by 25%.

R=ken2
CC=golang-dev
https://golang.org/cl/4383047

3 files changed, 33 insertions, 36 deletions

diff --git a/src/cmd/6l/asm.c b/src/cmd/6l/asm.c
index 3e2fe69604..ba2074fde0 100644
--- a/src/cmd/6l/asm.c
+++ b/src/cmd/6l/asm.c
@@ -1101,37 +1101,34 @@ genasmsym(void (*put)(Sym*, char*, int, vlong, vlong, int, Sym*))
 {
 	Auto *a;
 	Sym *s;
-	int h;
 
-	for(h=0; h<NHASH; h++) {
-		for(s=hash[h]; s!=S; s=s->hash) {
-			if(s->hide)
-				continue;
-			switch(s->type&~SSUB) {
-			case SCONST:
-			case SRODATA:
-			case SDATA:
-			case SELFDATA:
-			case SMACHOGOT:
-			case STYPE:
-			case SSTRING:
-			case SGOSTRING:
-			case SWINDOWS:
-				if(!s->reachable)
-					continue;
-				put(s, s->name, 'D', symaddr(s), s->size, s->version, s->gotype);
+	for(s=allsym; s!=S; s=s->allsym) {
+		if(s->hide)
+			continue;
+		switch(s->type&~SSUB) {
+		case SCONST:
+		case SRODATA:
+		case SDATA:
+		case SELFDATA:
+		case SMACHOGOT:
+		case STYPE:
+		case SSTRING:
+		case SGOSTRING:
+		case SWINDOWS:
+			if(!s->reachable)
 				continue;
+			put(s, s->name, 'D', symaddr(s), s->size, s->version, s->gotype);
+			continue;
 
-			case SBSS:
-				if(!s->reachable)
-					continue;
-				put(s, s->name, 'B', symaddr(s), s->size, s->version, s->gotype);
+		case SBSS:
+			if(!s->reachable)
 				continue;
+			put(s, s->name, 'B', symaddr(s), s->size, s->version, s->gotype);
+			continue;
 
-			case SFILE:
-				put(nil, s->name, 'f', s->value, 0, s->version, 0);
-				continue;
-			}
+		case SFILE:
+			put(nil, s->name, 'f', s->value, 0, s->version, 0);
+			continue;
 		}
 	}
 
diff --git a/src/cmd/6l/l.h b/src/cmd/6l/l.h
index 139b06af89..4fc13b94ae 100644
--- a/src/cmd/6l/l.h
+++ b/src/cmd/6l/l.h
@@ -138,6 +138,7 @@ struct	Sym
 	int32	plt;
 	int32	got;
 	Sym*	hash;	// in hash table
+	Sym*	allsym;	// in all symbol list
 	Sym*	next;	// in text or data list
 	Sym*	sub;	// in SSUB list
 	Sym*	outer;	// container of sub
@@ -178,7 +179,6 @@ struct	Movtab
 
 enum
 {
-	NHASH		= 10007,
 	MINSIZ		= 8,
 	STRINGSZ	= 200,
 	MINLC		= 1,
diff --git a/src/cmd/6l/obj.c b/src/cmd/6l/obj.c
index f113e3ec1e..6b43d2df43 100644
--- a/src/cmd/6l/obj.c
+++ b/src/cmd/6l/obj.c
@@ -287,7 +287,7 @@ zsym(char *pn, Biobuf *f, Sym *h[])
 {	
 	int o;
 	
-	o = Bgetc(f);
+	o = BGETC(f);
 	if(o < 0 || o >= NSYM || h[o] == nil)
 		mangle(pn);
 	return h[o];
@@ -301,12 +301,12 @@ zaddr(char *pn, Biobuf *f, Adr *a, Sym *h[])
 	Sym *s;
 	Auto *u;
 
-	t = Bgetc(f);
+	t = BGETC(f);
 	a->index = D_NONE;
 	a->scale = 0;
 	if(t & T_INDEX) {
-		a->index = Bgetc(f);
-		a->scale = Bgetc(f);
+		a->index = BGETC(f);
+		a->scale = BGETC(f);
 	}
 	a->offset = 0;
 	if(t & T_OFFSET) {
@@ -330,7 +330,7 @@ zaddr(char *pn, Biobuf *f, Adr *a, Sym *h[])
 		a->type = D_SCONST;
 	}
 	if(t & T_TYPE)
-		a->type = Bgetc(f);
+		a->type = BGETC(f);
 	if(a->type < 0 || a->type >= D_SIZE)
 		mangle(pn);
 	adrgotype = S;
@@ -405,10 +405,10 @@ newloop:
 loop:
 	if(f->state == Bracteof || Boffset(f) >= eof)
 		goto eof;
-	o = Bgetc(f);
+	o = BGETC(f);
 	if(o == Beof)
 		goto eof;
-	o |= Bgetc(f) << 8;
+	o |= BGETC(f) << 8;
 	if(o <= AXXX || o >= ALAST) {
 		if(o < 0)
 			goto eof;
@@ -421,8 +421,8 @@ loop:
 		sig = 0;
 		if(o == ASIGNAME)
 			sig = Bget4(f);
-		v = Bgetc(f);	/* type */
-		o = Bgetc(f);	/* sym */
+		v = BGETC(f);	/* type */
+		o = BGETC(f);	/* sym */
 		r = 0;
 		if(v == D_STATIC)
 			r = version;