1 files changed, 176 insertions, 0 deletions
diff --git a/src/Ryujinx.Graphics.Shader/Translation/ControlFlowGraph.cs b/src/Ryujinx.Graphics.Shader/Translation/ControlFlowGraph.cs
new file mode 100644
index 00000000..65328fd7
--- /dev/null
+++ b/src/Ryujinx.Graphics.Shader/Translation/ControlFlowGraph.cs
@@ -0,0 +1,176 @@
+using Ryujinx.Graphics.Shader.IntermediateRepresentation;
+using System.Collections.Generic;
+
+namespace Ryujinx.Graphics.Shader.Translation
+{
+    class ControlFlowGraph
+    {
+        public BasicBlock[] Blocks { get; }
+        public BasicBlock[] PostOrderBlocks { get; }
+        public int[] PostOrderMap { get; }
+
+        public ControlFlowGraph(BasicBlock[] blocks)
+        {
+            Blocks = blocks;
+
+            HashSet<BasicBlock> visited = new HashSet<BasicBlock>();
+
+            Stack<BasicBlock> blockStack = new Stack<BasicBlock>();
+
+            List<BasicBlock> postOrderBlocks = new List<BasicBlock>(blocks.Length);
+
+            PostOrderMap = new int[blocks.Length];
+
+            visited.Add(blocks[0]);
+
+            blockStack.Push(blocks[0]);
+
+            while (blockStack.TryPop(out BasicBlock block))
+            {
+                if (block.Next != null && visited.Add(block.Next))
+                {
+                    blockStack.Push(block);
+                    blockStack.Push(block.Next);
+                }
+                else if (block.Branch != null && visited.Add(block.Branch))
+                {
+                    blockStack.Push(block);
+                    blockStack.Push(block.Branch);
+                }
+                else
+                {
+                    PostOrderMap[block.Index] = postOrderBlocks.Count;
+
+                    postOrderBlocks.Add(block);
+                }
+            }
+
+            PostOrderBlocks = postOrderBlocks.ToArray();
+        }
+
+        public static ControlFlowGraph Create(Operation[] operations)
+        {
+            Dictionary<Operand, BasicBlock> labels = new Dictionary<Operand, BasicBlock>();
+
+            List<BasicBlock> blocks = new List<BasicBlock>();
+
+            BasicBlock currentBlock = null;
+
+            void NextBlock(BasicBlock nextBlock)
+            {
+                if (currentBlock != null && !EndsWithUnconditionalInst(currentBlock.GetLastOp()))
+                {
+                    currentBlock.Next = nextBlock;
+                }
+
+                currentBlock = nextBlock;
+            }
+
+            void NewNextBlock()
+            {
+                BasicBlock block = new BasicBlock(blocks.Count);
+
+                blocks.Add(block);
+
+                NextBlock(block);
+            }
+
+            bool needsNewBlock = true;
+
+            for (int index = 0; index < operations.Length; index++)
+            {
+                Operation operation = operations[index];
+
+                if (operation.Inst == Instruction.MarkLabel)
+                {
+                    Operand label = operation.Dest;
+
+                    if (labels.TryGetValue(label, out BasicBlock nextBlock))
+                    {
+                        nextBlock.Index = blocks.Count;
+
+                        blocks.Add(nextBlock);
+
+                        NextBlock(nextBlock);
+                    }
+                    else
+                    {
+                        NewNextBlock();
+
+                        labels.Add(label, currentBlock);
+                    }
+                }
+                else
+                {
+                    if (needsNewBlock)
+                    {
+                        NewNextBlock();
+                    }
+
+                    currentBlock.Operations.AddLast(operation);
+                }
+
+                needsNewBlock = operation.Inst == Instruction.Branch       ||
+                                operation.Inst == Instruction.BranchIfTrue ||
+                                operation.Inst == Instruction.BranchIfFalse;
+
+                if (needsNewBlock)
+                {
+                    Operand label = operation.Dest;
+
+                    if (!labels.TryGetValue(label, out BasicBlock branchBlock))
+                    {
+                        branchBlock = new BasicBlock();
+
+                        labels.Add(label, branchBlock);
+                    }
+
+                    currentBlock.Branch = branchBlock;
+                }
+            }
+
+            // Remove unreachable blocks.
+            bool hasUnreachable;
+
+            do
+            {
+                hasUnreachable = false;
+
+                for (int blkIndex = 1; blkIndex < blocks.Count; blkIndex++)
+                {
+                    BasicBlock block = blocks[blkIndex];
+
+                    if (block.Predecessors.Count == 0)
+                    {
+                        block.Next = null;
+                        block.Branch = null;
+                        blocks.RemoveAt(blkIndex--);
+                        hasUnreachable = true;
+                    }
+                    else
+                    {
+                        block.Index = blkIndex;
+                    }
+                }
+            } while (hasUnreachable);
+
+            return new ControlFlowGraph(blocks.ToArray());
+        }
+
+        private static bool EndsWithUnconditionalInst(INode node)
+        {
+            if (node is Operation operation)
+            {
+                switch (operation.Inst)
+                {
+                    case Instruction.Branch:
+                    case Instruction.Discard:
+                    case Instruction.Return:
+                        return true;
+                }
+            }
+
+            return false;
+        }
+    }
+}
+\ No newline at end of file