late uop_bufs [pr] (#7438)

tinygrad/engine/schedule.py

@@ -42,7 +42,6 @@ class ScheduleItem:
 class ScheduleContext:
   realizes: Dict[Buffer, LazyBuffer]
   buf_uops: Dict[Buffer, UOp] = field(default_factory=dict)
-  uop_bufs: Dict[UOp, Buffer] = field(default_factory=dict)
   ubuf_metadata: Dict[UOp, Metadata] = field(default_factory=dict)
   var_vals: Dict[Variable, int] = field(default_factory=dict)
 
@@ -59,7 +58,6 @@ def to_uop(buf:LazyBuffer, realizes:Dict[UOp, UOp], ctx:ScheduleContext, cache:D
   # everything else has BUFFER
   if (b:=buf.buffer) not in ctx.buf_uops:
     ctx.buf_uops[b] = ubuf = UOp(UOps.BUFFER, b.dtype.ptr(), (), (len(ctx.buf_uops), (b.device, b.size, b.dtype)))
-    ctx.uop_bufs[ubuf] = b
     if b in ctx.realizes: realizes[ubuf] = ubuf
   else: ubuf = ctx.buf_uops[b]
   # if the buffer is already realized we just load it
@@ -251,14 +249,15 @@ def create_schedule_with_vars(outs:List[LazyBuffer]) -> Tuple[List[ScheduleItem]
     small_graphs.append(full_ast_rewrite(sink, ctx.var_vals, assigned))
 
   # do BFS
-  prescheduled = [ScheduleItem(u, tuple(b for u in c.bufs if (b:=ctx.uop_bufs[u]).size != 0),
+  bufs = list(ctx.buf_uops)
+  prescheduled = [ScheduleItem(u, tuple(b for u in c.bufs if (b:=bufs[u.arg[0]]).size != 0),
                                tuple(m), tuple(c.assign_preloads)) for (u,c),m in zip(small_graphs, metadata)]
   schedule_targets = {out:si for si in prescheduled for out in si.outputs}
   graph: DefaultDict[ScheduleItem, List[ScheduleItem]] = defaultdict(list)
   in_degree: DefaultDict[ScheduleItem, int] = defaultdict(int)
   for si in prescheduled:
     # realize outputs before a parent is assigned to
-    parents_assigns = dedup(xsi for x in si.assign_preloads if (xsi:=schedule_targets.get(ctx.uop_bufs[x])) and xsi is not si)
+    parents_assigns = dedup(xsi for x in si.assign_preloads if (xsi:=schedule_targets.get(bufs[x.arg[0]])) and xsi is not si)
     for assign in parents_assigns:
       graph[si].append(assign)
       in_degree[assign] += 1