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