1 files changed, 171 insertions, 0 deletions
diff --git a/src/Ryujinx.Cpu/LightningJit/Graph/DataFlow.cs b/src/Ryujinx.Cpu/LightningJit/Graph/DataFlow.cs
new file mode 100644
index 00000000..e5b369d6
--- /dev/null
+++ b/src/Ryujinx.Cpu/LightningJit/Graph/DataFlow.cs
@@ -0,0 +1,171 @@
+namespace Ryujinx.Cpu.LightningJit.Graph
+{
+    static class DataFlow
+    {
+        public static (RegisterMask[], RegisterMask[]) GetGlobalUses(IBlockList blocks)
+        {
+            // Compute local register inputs and outputs used inside blocks.
+            RegisterMask[] localInputs = new RegisterMask[blocks.Count];
+            RegisterMask[] localOutputs = new RegisterMask[blocks.Count];
+
+            for (int index = 0; index < blocks.Count; index++)
+            {
+                IBlock block = blocks[index];
+
+                RegisterUse use = block.ComputeUseMasks();
+
+                localInputs[block.Index] = use.Read;
+                localOutputs[block.Index] = use.Write;
+            }
+
+            // Compute global register inputs and outputs used across blocks.
+            RegisterMask[] globalInputs = new RegisterMask[blocks.Count];
+            RegisterMask[] globalOutputs = new RegisterMask[blocks.Count];
+
+            bool modified;
+
+            // Compute register outputs.
+            do
+            {
+                modified = false;
+
+                for (int index = 0; index < blocks.Count; index++)
+                {
+                    IBlock block = blocks[index];
+
+                    int firstPIndex = GetFirstPredecessorIndex(block);
+                    if (firstPIndex >= 0)
+                    {
+                        IBlock predecessor = block.GetPredecessor(firstPIndex);
+
+                        RegisterMask outputs = globalOutputs[predecessor.Index];
+
+                        for (int pIndex = firstPIndex + 1; pIndex < block.PredecessorsCount; pIndex++)
+                        {
+                            predecessor = block.GetPredecessor(pIndex);
+
+                            if (predecessor.EndsWithContextStore())
+                            {
+                                // If a block ended with a context store, then we don't need to care
+                                // about any of it's outputs, as they have already been saved to the context.
+                                // Common outputs must be reset as doing a context stores indicates we will
+                                // do a function call and wipe all register values.
+
+                                continue;
+                            }
+
+                            outputs |= globalOutputs[predecessor.Index];
+                        }
+
+                        outputs |= localOutputs[block.Index];
+                        modified |= Exchange(globalOutputs, block.Index, globalOutputs[block.Index] | outputs);
+                    }
+                    else
+                    {
+                        modified |= Exchange(globalOutputs, block.Index, localOutputs[block.Index]);
+                    }
+                }
+            }
+            while (modified);
+
+            // Compute register inputs.
+            do
+            {
+                modified = false;
+
+                for (int index = blocks.Count - 1; index >= 0; index--)
+                {
+                    IBlock block = blocks[index];
+
+                    RegisterMask cmnOutputs = RegisterMask.Zero;
+                    RegisterMask allOutputs = RegisterMask.Zero;
+
+                    int firstPIndex = GetFirstPredecessorIndex(block);
+                    if (firstPIndex == 0)
+                    {
+                        IBlock predecessor = block.GetPredecessor(0);
+
+                        // Assumes that block index 0 is the entry block.
+                        cmnOutputs = block.Index != 0 ? globalOutputs[predecessor.Index] : RegisterMask.Zero;
+                        allOutputs = globalOutputs[predecessor.Index];
+
+                        for (int pIndex = 1; pIndex < block.PredecessorsCount; pIndex++)
+                        {
+                            predecessor = block.GetPredecessor(pIndex);
+
+                            if (!predecessor.EndsWithContextStore())
+                            {
+                                RegisterMask outputs = globalOutputs[predecessor.Index];
+
+                                cmnOutputs &= outputs;
+                                allOutputs |= outputs;
+                            }
+                            else
+                            {
+                                cmnOutputs = RegisterMask.Zero;
+                            }
+                        }
+                    }
+                    else if (firstPIndex > 0)
+                    {
+                        IBlock predecessor = block.GetPredecessor(firstPIndex);
+
+                        allOutputs = globalOutputs[predecessor.Index];
+
+                        for (int pIndex = firstPIndex + 1; pIndex < block.PredecessorsCount; pIndex++)
+                        {
+                            predecessor = block.GetPredecessor(pIndex);
+
+                            if (!predecessor.EndsWithContextStore())
+                            {
+                                allOutputs |= globalOutputs[predecessor.Index];
+                            }
+                        }
+                    }
+
+                    RegisterMask inputs = localInputs[block.Index];
+
+                    // If this block will load from context at the end,
+                    // we don't need to care about what comes next.
+                    if (!block.EndsWithContextLoad())
+                    {
+                        for (int sIndex = 0; sIndex < block.SuccessorsCount; sIndex++)
+                        {
+                            inputs |= globalInputs[block.GetSuccessor(sIndex).Index] & ~localOutputs[block.Index];
+                        }
+                    }
+
+                    inputs |= allOutputs & ~localOutputs[block.Index];
+                    inputs &= ~cmnOutputs;
+
+                    modified |= Exchange(globalInputs, block.Index, globalInputs[block.Index] | inputs);
+                }
+            }
+            while (modified);
+
+            return (globalInputs, globalOutputs);
+        }
+
+        private static bool Exchange(RegisterMask[] masks, int blkIndex, RegisterMask value)
+        {
+            ref RegisterMask curValue = ref masks[blkIndex];
+            bool changed = curValue != value;
+            curValue = value;
+
+            return changed;
+        }
+
+        private static int GetFirstPredecessorIndex(IBlock block)
+        {
+            for (int pIndex = 0; pIndex < block.PredecessorsCount; pIndex++)
+            {
+                if (!block.GetPredecessor(pIndex).EndsWithContextStore())
+                {
+                    return pIndex;
+                }
+            }
+
+            return -1;
+        }
+    }
+}