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

1 files changed, 10 insertions, 22 deletions

diff --git a/src/cmd/ld/symtab.c b/src/cmd/ld/symtab.c
index f1d44058e0..aefe0b1af0 100644
--- a/src/cmd/ld/symtab.c
+++ b/src/cmd/ld/symtab.c
@@ -340,7 +340,6 @@ putsymb(Sym *s, char *name, int t, vlong v, vlong size, int ver, Sym *typ)
 void
 symtab(void)
 {
-	int32 h;
 	Sym *s;
 
 	// Define these so that they'll get put into the symbol table.
@@ -361,11 +360,6 @@ symtab(void)
 	s->size = 0;
 	s->reachable = 1;
 
-	s = lookup("string.*", 0);
-	s->type = SSTRING;
-	s->size = 0;
-	s->reachable = 1;
-
 	s = lookup("go.string.*", 0);
 	s->type = SGOSTRING;
 	s->size = 0;
@@ -380,22 +374,16 @@ symtab(void)
 	// within a type they sort by size, so the .* symbols
 	// just defined above will be first.
 	// hide the specific symbols.
-	for(h=0; h<NHASH; h++) {
-		for(s=hash[h]; s!=S; s=s->hash){
-			if(!s->reachable || s->special || s->type != SRODATA)
-				continue;
-			if(strncmp(s->name, "type.", 5) == 0) {
-				s->type = STYPE;
-				s->hide = 1;
-			}
-			if(strncmp(s->name, "string.", 7) == 0) {
-				s->type = SSTRING;
-				s->hide = 1;
-			}
-			if(strncmp(s->name, "go.string.", 10) == 0) {
-				s->type = SGOSTRING;
-				s->hide = 1;
-			}
+	for(s = allsym; s != S; s = s->allsym) {
+		if(!s->reachable || s->special || s->type != SRODATA)
+			continue;
+		if(strncmp(s->name, "type.", 5) == 0) {
+			s->type = STYPE;
+			s->hide = 1;
+		}
+		if(strncmp(s->name, "go.string.", 10) == 0) {
+			s->type = SGOSTRING;
+			s->hide = 1;
 		}
 	}