use jl_gf_invoke_lookup in typeinf to lookup the method to be called

base/inference.jl

@@ -706,26 +706,20 @@ function invoke_tfunc(f, types, argtype)
     if is(argtype,Bottom)
         return Bottom
     end
-    applicable = _methods(f, types, -1)
-    if isempty(applicable)
+    meth = ccall(:jl_gf_invoke_lookup, Any, (Any, Any), f, types)
+    if is(meth, nothing)
         return Any
     end
-    for (m::SimpleVector) in applicable
-        local linfo
-        try
-            linfo = func_for_method(m[3],types,m[2])
-        catch
-            return Any
-        end
-        if typeseq(m[1],types)
-            tvars = m[2][1:2:end]
-            (ti, env) = ccall(:jl_match_method, Any, (Any,Any,Any),
-                              argtype, m[1], tvars)::SimpleVector
-            (_tree,rt) = typeinf(linfo, ti, env, linfo)
-            return rt
-        end
+    (ti, env) = ccall(:jl_match_method, Any, (Any, Any, Any),
+                      argtype, meth.sig, meth.tvars)::SimpleVector
+    local linfo
+    try
+        linfo = func_for_method(meth, types, env)
+    catch
+        return Any
     end
-    return Any
+    (_tree, rt) = typeinf(linfo, ti, env, linfo)
+    return rt
 end
 
 # `types` is an array of inferred types for expressions in `args`.