rustc: Avoid SHA-1 hashing every type, since they're interned

Author: pcwalton

src/comp/back/link.rs

@@ -399,38 +399,18 @@ fn truncated_sha1_result(sha1 sha) -> str {
     ret str::substr(sha.result_str(), 0u, 16u);
 }
 
-
-// This calculates STH for a symbol, as defined above
-fn symbol_hash(ty::ctxt tcx, sha1 sha, &ty::t t,
-               &link_meta link_meta) -> str {
-    // NB: do *not* use abbrevs here as we want the symbol names
-    // to be independent of one another in the crate.
-
+fn hash_link_meta(sha1 sha, &link_meta link_meta) -> str {
     sha.reset();
     sha.input_str(link_meta.name);
     sha.input_str("-");
-    // FIXME: This wants to be link_meta.meta_hash
-    sha.input_str(link_meta.name);
+    sha.input_str(link_meta.vers);
     sha.input_str("-");
-    sha.input_str(encoder::encoded_ty(tcx, t));
-    auto hash = truncated_sha1_result(sha);
-    // Prefix with _ so that it never blends into adjacent digits
-
-    ret "_" + hash;
+    sha.input_str(link_meta.extras_hash);
+    ret truncated_sha1_result(sha);
 }
 
 fn get_symbol_hash(&@crate_ctxt ccx, &ty::t t) -> str {
-    auto hash = "";
-    alt (ccx.type_sha1s.find(t)) {
-        case (some(?h)) { hash = h; }
-        case (none) {
-            hash =
-                symbol_hash(ccx.tcx, ccx.sha, t,
-                            ccx.link_meta);
-            ccx.type_sha1s.insert(t, hash);
-        }
-    }
-    ret hash;
+    ret #fmt("_%s_%u", ccx.link_meta_hash, t);
 }
 
 fn mangle(&str[] ss) -> str {

src/comp/middle/trans.rs

@@ -136,6 +136,7 @@ type crate_ctxt =
         hashmap[ast::node_id, str] item_symbols,
         mutable option::t[ValueRef] main_fn,
         link::link_meta link_meta,
+        str link_meta_hash,
 
         // TODO: hashmap[tup(tag_id,subtys), @tag_info]
         hashmap[ty::t, uint] tag_sizes,
@@ -150,7 +151,6 @@ type crate_ctxt =
         @glue_fns glues,
         namegen names,
         std::sha1::sha1 sha,
-        hashmap[ty::t, str] type_sha1s,
         hashmap[ty::t, str] type_short_names,
         ty::ctxt tcx,
         stats stats,
@@ -8601,9 +8601,9 @@ fn trans_crate(&session::session sess, &@ast::crate crate, &ty::ctxt tcx,
     auto tag_sizes = map::mk_hashmap[ty::t, uint](hasher, eqer);
     auto tydescs = map::mk_hashmap[ty::t, @tydesc_info](hasher, eqer);
     auto lltypes = map::mk_hashmap[ty::t, TypeRef](hasher, eqer);
-    auto sha1s = map::mk_hashmap[ty::t, str](hasher, eqer);
     auto short_names = map::mk_hashmap[ty::t, str](hasher, eqer);
     auto sha = std::sha1::mk_sha1();
+    auto link_meta = link::build_link_meta(sess, *crate, output, sha);
     auto ccx =
         @rec(sess=sess,
              llmod=llmod,
@@ -8615,7 +8615,8 @@ fn trans_crate(&session::session sess, &@ast::crate crate, &ty::ctxt tcx,
              ast_map=amap,
              item_symbols=new_int_hash[str](),
              mutable main_fn=none[ValueRef],
-             link_meta=link::build_link_meta(sess, *crate, output, sha),
+             link_meta=link_meta,
+             link_meta_hash=link::hash_link_meta(sha, link_meta),
              tag_sizes=tag_sizes,
              discrims=new_int_hash[ValueRef](),
              discrim_symbols=new_int_hash[str](),
@@ -8628,7 +8629,6 @@ fn trans_crate(&session::session sess, &@ast::crate crate, &ty::ctxt tcx,
              glues=glues,
              names=namegen(0),
              sha=sha,
-             type_sha1s=sha1s,
              type_short_names=short_names,
              tcx=tcx,
              stats=rec(mutable n_static_tydescs=0u,