Rewrite each_path to allow performance improvements in the future.

Instead of determining paths from the path tag, we iterate through
modules' children recursively in the metadata. This will allow for
lazy external module resolution.

src/libextra/sync.rs

@@ -381,7 +381,7 @@ impl Sem<~[Waitqueue]> {
     // The only other places that condvars get built are rwlock.write_cond()
     // and rwlock_write_mode.
     pub fn access_cond<U>(&self, blk: &fn(c: &Condvar) -> U) -> U {
-        do self.access {
+        do self.access_waitqueue {
             blk(&Condvar { sem: self, order: Nothing })
         }
     }

src/librustc/metadata/common.rs

@@ -176,6 +176,10 @@ pub static tag_item_method_tps: uint = 0x7b;
 pub static tag_item_method_fty: uint = 0x7c;
 pub static tag_item_method_transformed_self_ty: uint = 0x7d;
 
+pub static tag_mod_child: uint = 0x7e;
+pub static tag_misc_info: uint = 0x7f;
+pub static tag_misc_info_crate_items: uint = 0x80;
+
 pub struct LinkMeta {
     name: @str,
     vers: @str,

src/librustc/metadata/csearch.rs

@@ -97,18 +97,14 @@ pub fn get_enum_variants(tcx: ty::ctxt, def: ast::def_id)
     return decoder::get_enum_variants(cstore.intr, cdata, def.node, tcx)
 }
 
-pub fn get_impls_for_mod(cstore: @mut cstore::CStore, def: ast::def_id,
-                         name: Option<ast::ident>)
-                      -> @~[@resolve::Impl] {
-    let cdata = cstore::get_crate_data(cstore, def.crate);
-    do decoder::get_impls_for_mod(cstore.intr, cdata, def.node, name) |cnum| {
-        cstore::get_crate_data(cstore, cnum)
-    }
+/// Returns information about the given implementation.
+pub fn get_impl(cstore: @mut cstore::CStore, impl_def_id: ast::def_id)
+                -> resolve::Impl {
+    let cdata = cstore::get_crate_data(cstore, impl_def_id.crate);
+    decoder::get_impl(cstore.intr, cdata, impl_def_id.node)
 }
 
-pub fn get_method(tcx: ty::ctxt,
-                  def: ast::def_id) -> ty::Method
-{
+pub fn get_method(tcx: ty::ctxt, def: ast::def_id) -> ty::Method {
     let cdata = cstore::get_crate_data(tcx.cstore, def.crate);
     decoder::get_method(tcx.cstore.intr, cdata, def.node, tcx)
 }