Send string concatenation to specialized upcall, shave 17s off librustc compile time.

2 files changed, 10 insertions, 5 deletions

diff --git a/src/rustc/back/upcall.rs b/src/rustc/back/upcall.rs
index a0bb2c5937d..cf862d3ca44 100644
--- a/src/rustc/back/upcall.rs
+++ b/src/rustc/back/upcall.rs
@@ -18,6 +18,7 @@ type upcalls =
      mark: ValueRef,
      vec_grow: ValueRef,
      vec_push: ValueRef,
+     str_concat: ValueRef,
      cmp_type: ValueRef,
      log_type: ValueRef,
      alloc_c_stack: ValueRef,
@@ -69,6 +70,9 @@ fn declare_upcalls(targ_cfg: @session::config,
               dvi("vec_push",
                 [T_ptr(T_ptr(opaque_vec_t)), T_ptr(tydesc_type),
                  T_ptr(T_i8())]),
+          str_concat:
+              d("str_concat", [T_ptr(opaque_vec_t), T_ptr(opaque_vec_t)],
+                T_ptr(opaque_vec_t)),
           cmp_type:
               dv("cmp_type",
                  [T_ptr(T_i1()), T_ptr(tydesc_type),
diff --git a/src/rustc/middle/trans/tvec.rs b/src/rustc/middle/trans/tvec.rs
index 34e0ccfaffb..c322e9255e0 100644
--- a/src/rustc/middle/trans/tvec.rs
+++ b/src/rustc/middle/trans/tvec.rs
@@ -194,15 +194,16 @@ fn trans_append_literal(bcx: block, vptrptr: ValueRef, vec_ty: ty::t,
 fn trans_add(bcx: block, vec_ty: ty::t, lhs: ValueRef,
              rhs: ValueRef, dest: dest) -> block {
     let ccx = bcx.ccx();
-    let strings = alt ty::get(vec_ty).struct {
-      ty::ty_str { true }
-      _ { false }
-    };
+
+    if ty::get(vec_ty).struct == ty::ty_str {
+        let n = Call(bcx, ccx.upcalls.str_concat, [lhs, rhs]);
+        ret base::store_in_dest(bcx, n, dest);
+    }
+
     let unit_ty = ty::sequence_element_type(bcx.tcx(), vec_ty);
     let llunitty = type_of::type_of(ccx, unit_ty);
 
     let lhs_fill = get_fill(bcx, lhs);
-    if strings { lhs_fill = Sub(bcx, lhs_fill, C_int(ccx, 1)); }
     let rhs_fill = get_fill(bcx, rhs);
     let new_fill = Add(bcx, lhs_fill, rhs_fill);
     let {bcx: bcx, val: new_vec_ptr} = alloc_raw(bcx, new_fill, new_fill);