using Ryujinx.Graphics.Shader.IntermediateRepresentation; using System.Collections.Generic; namespace Ryujinx.Graphics.Shader.Translation { static class Dominance { //Those methods are an implementation of the algorithms on "A Simple, Fast Dominance Algorithm". //https://www.cs.rice.edu/~keith/EMBED/dom.pdf public static void FindDominators(BasicBlock entry, int blocksCount) { HashSet visited = new HashSet(); Stack blockStack = new Stack(); List postOrderBlocks = new List(blocksCount); int[] postOrderMap = new int[blocksCount]; visited.Add(entry); blockStack.Push(entry); 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); } } BasicBlock Intersect(BasicBlock block1, BasicBlock block2) { while (block1 != block2) { while (postOrderMap[block1.Index] < postOrderMap[block2.Index]) { block1 = block1.ImmediateDominator; } while (postOrderMap[block2.Index] < postOrderMap[block1.Index]) { block2 = block2.ImmediateDominator; } } return block1; } entry.ImmediateDominator = entry; bool modified; do { modified = false; for (int blkIndex = postOrderBlocks.Count - 2; blkIndex >= 0; blkIndex--) { BasicBlock block = postOrderBlocks[blkIndex]; BasicBlock newIDom = null; foreach (BasicBlock predecessor in block.Predecessors) { if (predecessor.ImmediateDominator != null) { if (newIDom != null) { newIDom = Intersect(predecessor, newIDom); } else { newIDom = predecessor; } } } if (block.ImmediateDominator != newIDom) { block.ImmediateDominator = newIDom; modified = true; } } } while (modified); } public static void FindDominanceFrontiers(BasicBlock[] blocks) { for (int blkIndex = 0; blkIndex < blocks.Length; blkIndex++) { BasicBlock block = blocks[blkIndex]; if (block.Predecessors.Count < 2) { continue; } for (int pBlkIndex = 0; pBlkIndex < block.Predecessors.Count; pBlkIndex++) { BasicBlock current = block.Predecessors[pBlkIndex]; while (current != block.ImmediateDominator) { current.DominanceFrontiers.Add(block); current = current.ImmediateDominator; } } } } } }