[CINN] Add merge_all_horizontal_groups flag (#72775)

Author: huangjiyi

paddle/common/flags.cc

@@ -1402,6 +1402,16 @@ PHI_DEFINE_EXPORTED_bool(enable_fusion_result_check,
  false,
  "Whether enable fusion result check in cinn.");
 
+/**
+ * CINN all horizontal groups merge FLAG
+ * Name: FLAGS_merge_all_horizontal_groups
+ * Since Version: 3.0
+ * Value Range: bool, default=false
+ */
+PHI_DEFINE_EXPORTED_bool(merge_all_horizontal_groups,
+ false,
+ "Whether enable merge all horizontal groups in cinn.");
+
 /**
  * Conv Search cache max number related FLAG
  * Name: FLAGS_search_cache_max_number

paddle/fluid/pir/transforms/sub_graph_detector.cc

@@ -51,6 +51,7 @@
 #include "paddle/fluid/pir/dialect/operator/trait/onednn.h"
 #endif
 
+COMMON_DECLARE_bool(merge_all_horizontal_groups);
 REGISTER_FILE_SYMBOLS(sub_graph_detector);
 namespace pir {
 std::vector<pir::Operation*> InverselyTopologicalSort(pir::Block* block) {
@@ -782,7 +783,7 @@ void SubgraphDetector::SubgraphFusion() {
  auto subgraph_list = GetSubgraphList();
  VLOG(4) << "Merge non-related subgraphs (size=" << subgraph_list.size()
  << ")";
- if (subgraph_list.size() > 2048) return;
+ if (subgraph_list.size() > 2048 && !FLAGS_merge_all_horizontal_groups) return;
  for (size_t i = 0; i < subgraph_list.size(); ++i) {
  auto lhs = subgraph_list[i];
  if (!lhs->substitute) continue;