From 5ebd44aa1234ba726fa271580ef3da79f4795bd4 Mon Sep 17 00:00:00 2001
From: nimlgen <138685161+nimlgen@users.noreply.github.com>
Date: Fri, 5 Jun 2026 21:20:25 +0300
Subject: [PATCH] hcq2: merge queues (#16514)

* hcq2: mergw queues

* cleaner
---
 extra/hcq2/hcq2.py | 39 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/extra/hcq2/hcq2.py b/extra/hcq2/hcq2.py
index c6eb36540d..c39aaa7587 100644
--- a/extra/hcq2/hcq2.py
+++ b/extra/hcq2/hcq2.py
@@ -332,6 +332,42 @@ def add_stores(ctx:set[int], submit:UOp, q:UOp) -> UOp:
   return submit.replace(src=(q.replace(src=tuple(new_src)),))
 pm_add_inner_stores = PatternMatcher([(UPat(Ops.CUSTOM_FUNCTION, arg="submit", src=(UPat(Ops.LINEAR, name="q"),), name="submit"), add_stores)])
 
+# *****************
+# 4.1. merge queues
+
+def get_submit(ast:UOp) -> UOp: return next(u for u in ast.toposort() if u.op is Ops.CUSTOM_FUNCTION and u.arg == "submit")
+
+def merge_sinks(old_sink:UOp, new_sink:UOp) -> UOp:
+  old_submit, new_submit = get_submit(old_sink), get_submit(new_sink)
+  old_queue, new_queue = old_submit.src[0], new_submit.src[0]
+  merged_submit = new_submit.replace(src=(new_queue.replace(src=old_queue.src + new_queue.src),))
+  old_root = old_sink.src[0].substitute({old_submit: merged_submit})
+  new_anchor = merged_submit if old_sink.src[0] is old_submit else old_root
+  return new_sink.substitute({new_submit: new_anchor})
+
+def merge_queues(linear:UOp) -> UOp:
+  new_src:list[UOp] = []
+  opened_qs:dict[tuple[tuple[str, ...], str], UOp] = {} # (devs, queue) -> sink, kept in submit order
+
+  for call in linear.src:
+    if call.tag != "hcq":
+      new_src += [opened_qs.pop(k).call().rtag('hcq') for k in list(opened_qs)] + [call]
+      continue
+
+    devs, queue = get_submit(new_sink:=call.src[0]).src[0].arg
+    if (old_sink:=opened_qs.pop((devs, queue), None)) is not None:
+      new_sink = merge_sinks(old_sink, new_sink) # exact same queue: merge, and re-insert at the end
+    else:
+      # no such queue opened: close every open submit on this queue that shares a device, so submit order is kept
+      new_src += [opened_qs.pop(k).call().rtag('hcq') for k in [k for k in opened_qs if k[1] == queue and set(k[0]) & set(devs)]]
+    opened_qs[(devs, queue)] = new_sink
+
+  return linear.replace(src=tuple(new_src + [sink.call().rtag('hcq') for sink in opened_qs.values()]))
+pm_merge_queues = PatternMatcher([(UPat(Ops.LINEAR, name="linear"), merge_queues)])
+
+# *****************
+# 4.2. global sync
+
 def add_global_sync(ctx:set[tuple[str, ...]], submit:UOp, q:UOp) -> UOp|None:
   if (devs:=q.arg[0]) in ctx: return None
   ctx.add(devs)
@@ -342,7 +378,7 @@ def add_global_sync(ctx:set[tuple[str, ...]], submit:UOp, q:UOp) -> UOp|None:
 pm_add_global_sync = PatternMatcher([(UPat(Ops.CUSTOM_FUNCTION, arg="submit", src=(UPat(Ops.LINEAR, name="q"),), name="submit"), add_global_sync)])
 
 # *****************
-# 4.1. encode cmdbufs
+# 5.1. encode cmdbufs
 
 @functools.cache
 def get_pm_lower(name:str) -> PatternMatcher|None:
@@ -447,6 +483,7 @@ def hcq_schedule(linear:UOp) -> UOp:
   linear = graph_rewrite(linear, pm_add_finalizer, ctx=deps_ctx, walk=True, name="add finalizer")
   linear = graph_rewrite(linear, pm_add_inner_loads + pm_flatten_linear, ctx=(waited:=set()), walk=True, name="add loads", enter_calls=True)
   linear = graph_rewrite(linear, pm_add_inner_stores, ctx=waited, walk=True, name="add stores", enter_calls=True)
+  linear = graph_rewrite(linear, pm_merge_queues, name="merge queues")
   linear = graph_rewrite(linear, pm_add_global_sync, ctx=set(), walk=True, name="add global sync", enter_calls=True)
   linear = graph_rewrite(linear, pm_encode_cmdbufs, walk=True, name="encode cmdbufs", enter_calls=True)
   linear = graph_rewrite(linear, pm_lift_patches_to_cmdbuf, name="lift patches to cmdbuf", enter_calls=True)