Do not attempt to selection merge to existing ladder blocks.

1 files changed, 9 insertions, 1 deletions

diff --git a/cfg_structurizer.cpp b/cfg_structurizer.cpp
index b84fa6b..46377f8 100644
--- a/cfg_structurizer.cpp
+++ b/cfg_structurizer.cpp
@@ -2716,6 +2716,14 @@ void CFGStructurizer::find_selection_merges(unsigned pass)
 				idom = header;
 		}
 
+		// Similar, but also check if we have associated ladder blocks with the idom.
+		if (!idom->pred_back_edge)
+		{
+			auto *inner_loop_header = entry_block->get_innermost_loop_header_for(idom);
+			if (inner_loop_header && inner_loop_header->loop_ladder_block == node)
+				idom = const_cast<CFGNode *>(inner_loop_header);
+		}
+
 		if (pass == 0)
 		{
 			// Check that we're not merging ourselves into the aether.
@@ -2817,7 +2825,7 @@ void CFGStructurizer::find_selection_merges(unsigned pass)
 				//LOGI("Loop merge: %p (%s) -> %p (%s)\n", static_cast<const void *>(loop), loop->name.c_str(),
 				//     static_cast<const void *>(node), node->name.c_str());
 			}
-			else if (idom->loop_merge_block != node)
+			else if (idom->loop_merge_block != node && idom->loop_ladder_block != node)
 			{
 				auto *selection_idom = create_helper_succ_block(idom);
 				// If we split the loop header into the loop header -> selection merge header,