1 files changed, 46 insertions, 0 deletions

diff --git a/src/shader_recompiler/frontend/ir/post_order.cpp b/src/shader_recompiler/frontend/ir/post_order.cpp
new file mode 100644
index 000000000..16bc44101
--- /dev/null
+++ b/src/shader_recompiler/frontend/ir/post_order.cpp
@@ -0,0 +1,46 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <algorithm>
+
+#include <boost/container/flat_set.hpp>
+#include <boost/container/small_vector.hpp>
+
+#include "shader_recompiler/frontend/ir/basic_block.h"
+#include "shader_recompiler/frontend/ir/post_order.h"
+
+namespace Shader::IR {
+
+BlockList PostOrder(const AbstractSyntaxNode& root) {
+    boost::container::small_vector<Block*, 16> block_stack;
+    boost::container::flat_set<Block*> visited;
+    BlockList post_order_blocks;
+
+    if (root.type != AbstractSyntaxNode::Type::Block) {
+        throw LogicError("First node in abstract syntax list root is not a block");
+    }
+    Block* const first_block{root.data.block};
+    visited.insert(first_block);
+    block_stack.push_back(first_block);
+
+    while (!block_stack.empty()) {
+        Block* const block{block_stack.back()};
+        const auto visit{[&](Block* branch) {
+            if (!visited.insert(branch).second) {
+                return false;
+            }
+            // Calling push_back twice is faster than insert on MSVC
+            block_stack.push_back(block);
+            block_stack.push_back(branch);
+            return true;
+        }};
+        block_stack.pop_back();
+        if (std::ranges::none_of(block->ImmSuccessors(), visit)) {
+            post_order_blocks.push_back(block);
+        }
+    }
+    return post_order_blocks;
+}
+
+} // namespace Shader::IR