diff --git a/base/inference.jl b/base/inference.jl
index 3390e178a43a2..59651d25c0165 100644
--- a/base/inference.jl
+++ b/base/inference.jl
@@ -72,7 +72,6 @@ type InferenceState
     # whereas backedges is optimized for iteration
     edges::ObjectIdDict # a Dict{InferenceState, Vector{LineNum}}
     backedges::Vector{Tuple{InferenceState, Vector{LineNum}}}
-    li_edges::Vector{Any} # a Set{MethodInstance}
     # iteration fixed-point detection
     fixedpoint::Bool
     inworkq::Bool
@@ -167,8 +166,8 @@ type InferenceState
         end
 
         if cached && !toplevel
-            min_valid = min_age(linfo)
-            max_valid = max_age(linfo)
+            min_valid = min_age(linfo.def)
+            max_valid = max_age(linfo.def)
         else
             min_valid = UInt(0)
             max_valid = UInt(0)
@@ -181,7 +180,6 @@ type InferenceState
             ssavalue_uses, ssavalue_init,
             ObjectIdDict(), # Dict{InferenceState, Vector{LineNum}}(),
             Vector{Tuple{InferenceState, Vector{LineNum}}}(),
-            Vector{Any}(), # Set{MethodInstance}()
             false, false, optimize, inlining, cached, false, false)
         push!(active, frame)
         nactive[] += 1
@@ -211,26 +209,6 @@ function get_staged(li::MethodInstance)
     return src
 end
 
-# TODO: track the worlds for which this InferenceState
-# is being used, and split it if the WIP requires it
-function update_valid_ages!(sv::InferenceState)
-    if isdefined(sv.linfo, :backedges)
-        min_valid = sv.min_valid
-        max_valid = sv.max_valid
-        for li in sv.li_edges
-            li = li::MethodInstance
-            min_valid = max(min_valid, min_age(li))
-            max_valid = min(max_valid, max_age(li))
-        end
-        sv.min_valid = min_valid
-        sv.max_valid = max_valid
-    end
-end
-function update_valid_age!(li::MethodInstance, sv::InferenceState)
-    sv.min_valid = max(sv.min_valid, min_age(li))
-    sv.max_valid = min(sv.max_valid, max_age(li))
-end
-
 
 #### current global inference state ####
 
@@ -1543,15 +1521,45 @@ end
 inlining_enabled() = (JLOptions().can_inline == 1)
 coverage_enabled() = (JLOptions().code_coverage != 0)
 
+# TODO: track the worlds for which this InferenceState
+# is being used, and split it if the WIP requires it?
+function converge_valid_age!(sv::InferenceState)
+    # push the validity range of sv into its fixedpoint callers
+    # recursing as needed to cover the graph
+    for (i, _) in sv.backedges
+        if i.fixedpoint
+            updated = false
+            if i.min_valid < sv.min_valid
+                i.min_valid = sv.min_valid
+                updated = true
+            end
+            if i.max_valid > sv.max_valid
+                i.max_valid = sv.max_valid
+                updated = true
+            end
+            if updated
+                converge_valid_age!(i)
+            end
+        end
+    end
+    nothing
+end
+function update_valid_age!(edge::InferenceState, sv::InferenceState)
+    sv.min_valid = max(edge.min_valid, sv.min_valid)
+    sv.max_valid = min(edge.max_valid, sv.max_valid)
+    nothing
+end
+function update_valid_age!(li::MethodInstance, sv::InferenceState)
+    sv.min_valid = max(sv.min_valid, min_age(li))
+    sv.max_valid = min(sv.max_valid, max_age(li))
+    nothing
+end
 function add_backedge(li::MethodInstance, sv::InferenceState)
     caller = sv.linfo
     isdefined(caller, :def) || return # don't add backedges to toplevel exprs
     isdefined(li, :backedges) || (li.backedges = []) # lazy-init the backedges array
     in(caller, li.backedges) || push!(li.backedges, caller) # add a backedge from callee to caller
     update_valid_age!(li, sv)
-    if li.inInference
-        in(li, sv.li_edges) || push!(sv.li_edges, li) # add a forward edge from caller to callee
-    end
     nothing
 end
 function add_mt_backedge(mt::MethodTable, sv::InferenceState)
@@ -1675,8 +1683,6 @@ function typeinf_edge(method::Method, atypes::ANY, sparams::SimpleVector, needtr
     end
 
     ccall(:jl_typeinf_begin, Void, ())
-    # XXX: the following logic is likely subtly broken if code.code was nothing,
-    #      although it seems unlikely something bad (infinite recursion) will happen as a result
     if linfo.inInference
         # inference on this signature may be in progress,
         # find the corresponding frame in the active list
@@ -1691,7 +1697,7 @@ function typeinf_edge(method::Method, atypes::ANY, sparams::SimpleVector, needtr
         # TODO: this assertion seems iffy
         assert(frame !== nothing)
     else
-        # TODO: verify again here that linfo wasn't just inferred
+        # XXX: the following logic needs to repeat the test for linfo.inferred now that it hold the lock
         # inference not started yet, make a new frame for a new lambda
         if method.isstaged
             try
@@ -1712,6 +1718,7 @@ function typeinf_edge(method::Method, atypes::ANY, sparams::SimpleVector, needtr
         # if we were called from inside inference, the caller will be the InferenceState object
         # for which the edge was required
         caller = caller::InferenceState
+        update_valid_age!(frame, caller)
         if !caller.inferred
             if haskey(caller.edges, frame)
                 Ws = caller.edges[frame]::Vector{Int}
@@ -1727,7 +1734,6 @@ function typeinf_edge(method::Method, atypes::ANY, sparams::SimpleVector, needtr
         end
     end
     typeinf_loop(frame)
-    isa(caller, InferenceState) && add_backedge(linfo, caller::InferenceState)
     ccall(:jl_typeinf_end, Void, ())
     return (frame.src, widenconst(frame.bestguess), frame.inferred && frame.optimized)
 end
@@ -1804,8 +1810,12 @@ function typeinf_loop(frame)
                         i.inworkq = true
                     end
                 end
+                for i in fplist
+                    # push valid ages from each node across the graph
+                    converge_valid_age!(i::InferenceState)
+                end
                 for i in length(fplist):-1:1
-                    finish(fplist[i]) # this may add incomplete work to active
+                    finish(fplist[i]::InferenceState) # this may add incomplete work to active
                 end
             end
         end
@@ -1972,8 +1982,8 @@ function typeinf_frame(frame)
         else # fixedpoint propagation
             for (i, _) in frame.edges
                 i = i::InferenceState
-                update_valid_ages!(i) # converge age at the same time
                 if !i.fixedpoint
+                    update_valid_age!(i, frame) # work towards converging age at the same time
                     if !i.inworkq
                         push!(workq, i)
                         i.inworkq = true
@@ -1994,7 +2004,7 @@ function unmark_fixedpoint(frame::InferenceState)
     # based upon (recursively) assuming that frame was stuck
     if frame.fixedpoint
         frame.fixedpoint = false
-        for (i,_) in frame.backedges
+        for (i, _) in frame.backedges
             unmark_fixedpoint(i)
         end
     end
@@ -2028,8 +2038,9 @@ end
 # inference completed on `me`
 # update the MethodInstance and notify the edges
 function finish(me::InferenceState)
-    for (i,_) in me.edges
-        @assert (i::InferenceState).fixedpoint
+    for (i, _) in me.edges
+        i = i::InferenceState
+        @assert i.fixedpoint
     end
     # below may call back into inference and
     # see this InferenceState is in an incomplete state
@@ -2119,7 +2130,6 @@ function finish(me::InferenceState)
                     inferred.code = ccall(:jl_compress_ast, Any, (Any, Any), me.linfo.def, inferred.code)
                 end
             end
-            update_valid_ages!(me)
             ccall(:jl_specialization_set_world, Void, (Any, UInt, UInt),
                   me.linfo, me.min_valid, me.max_valid)
         end
@@ -2127,25 +2137,26 @@ function finish(me::InferenceState)
         ccall(:jl_set_lambda_rettype, Void, (Any, Any, Any, Any), me.linfo, widenconst(me.bestguess), const_api, inferred)
     end
 
-    me.src.inferred = true
-    me.linfo.inInference = false
-    # finalize and record the linfo result
-    me.optimized = true
-
     # lazy-delete the item from active for several reasons:
     # efficiency, correctness, and recursion-safety
     nactive[] -= 1
     active[findlast(active, me)] = nothing
 
     # update all of the callers by traversing the backedges
-    for (i,_) in me.backedges
+    for (i, _) in me.backedges
         if !me.fixedpoint || !i.fixedpoint
             # wake up each backedge, unless both me and it already reached a fixed-point (cycle resolution stage)
             delete!(i.edges, me)
             i.inworkq || push!(workq, i)
             i.inworkq = true
         end
+        add_backedge(me.linfo, i) # add the real backedge now
     end
+
+    # finalize and record the linfo result
+    me.src.inferred = true
+    me.linfo.inInference = false
+    me.optimized = true
     nothing
 end
 
diff --git a/src/gf.c b/src/gf.c
index 312866fe41741..20519cc416d7e 100644
--- a/src/gf.c
+++ b/src/gf.c
@@ -141,8 +141,12 @@ JL_DLLEXPORT jl_method_instance_t *jl_specializations_get_linfo(jl_method_t *m,
     JL_GC_PUSH1(&li);
     // TODO: fuse lookup and insert steps
     assert(world >= m->min_world && world <= m->max_world);
+    size_t max_world = (jl_world_counter == world ? m->max_world : world);
+    li->min_world = world;
+    li->max_world = max_world;
+    assert(world <= max_world);
     jl_typemap_insert(&m->specializations, (jl_value_t*)m, type, jl_emptysvec, NULL, jl_emptysvec, (jl_value_t*)li, 0, &tfunc_cache,
-            world, world, NULL);
+            world, max_world, NULL);
     JL_UNLOCK(&m->writelock);
     JL_GC_POP();
     return li;
@@ -152,11 +156,7 @@ static int update_valid_world(jl_typemap_entry_t *entry, void *closure)
 {
     if (entry->func.value == closure) {
         jl_method_instance_t *li = (jl_method_instance_t*)closure;
-        // these asserts are based on how it is used currently from inference.jl
-        // they aren't really correct in general (well, in general, this method will corrupt the system state)
-        assert(entry->min_world == entry->max_world);
-        assert(li->min_world <= entry->min_world);
-        assert(li->max_world >= entry->max_world);
+        assert(li->min_world <= entry->min_world); // entry min_world should have been the same as li min_world before jl_specialization_set_world
         entry->min_world = li->min_world;
         entry->max_world = li->max_world;
     }
@@ -165,12 +165,15 @@ static int update_valid_world(jl_typemap_entry_t *entry, void *closure)
 JL_DLLEXPORT void jl_specialization_set_world(jl_method_instance_t *li, size_t min_world, size_t max_world)
 {
     assert(min_world <= max_world);
-    assert(li->min_world <= min_world);
-    assert(li->max_world >= max_world);
+    // this assert is based on how it is used currently from inference.jl
+    // it is really not correct in general (well, in general, this method will corrupt the system state)
+    assert(min_world <= li->min_world); // may widen lower bound, but don't expect to be narrowing it
+                                           // could be widening or narrowing upper bound
     li->min_world = min_world;
     li->max_world = max_world;
-    if (li->def != NULL)
+    if (li->def != NULL) {
         jl_typemap_visitor(li->def->specializations, update_valid_world, (void*)li);
+    }
 }
 
 JL_DLLEXPORT jl_value_t *jl_specializations_lookup(jl_method_t *m, jl_tupletype_t *type, size_t world)
@@ -854,7 +857,7 @@ static jl_method_instance_t *cache_method(jl_methtable_t *mt, union jl_typemap_t
     }
 
     jl_typemap_insert(cache, parent, origtype, jl_emptysvec, type, guardsigs, (jl_value_t*)newmeth, jl_cachearg_offset(mt), &lambda_cache,
-            m->min_world, m->max_world, NULL);
+            newmeth->min_world, newmeth->max_world, NULL);
 
     if (definition->traced && jl_method_tracer && allow_exec)
         jl_call_tracer(jl_method_tracer, (jl_value_t*)newmeth);