67 lines
2.2 KiB
C#
67 lines
2.2 KiB
C#
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using ARMeilleure.IntermediateRepresentation;
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using ARMeilleure.Translation;
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using System.Diagnostics;
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using static ARMeilleure.IntermediateRepresentation.OperandHelper;
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namespace ARMeilleure.CodeGen.Optimizations
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{
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static class BlockPlacement
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{
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public static void RunPass(ControlFlowGraph cfg)
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{
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bool update = false;
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BasicBlock block;
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BasicBlock nextBlock;
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BasicBlock lastBlock = cfg.Blocks.Last;
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// Move cold blocks at the end of the list, so that they are emitted away from hot code.
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for (block = cfg.Blocks.First; block != lastBlock; block = nextBlock)
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{
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nextBlock = block.ListNext;
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if (block.Frequency == BasicBlockFrequency.Cold)
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{
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cfg.Blocks.Remove(block);
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cfg.Blocks.AddLast(block);
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}
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}
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for (block = cfg.Blocks.First; block != null; block = nextBlock)
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{
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nextBlock = block.ListNext;
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if (block.SuccessorCount == 2 && block.Operations.Last is Operation branchOp)
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{
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Debug.Assert(branchOp.Instruction == Instruction.BranchIf);
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BasicBlock falseSucc = block.GetSuccessor(0);
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BasicBlock trueSucc = block.GetSuccessor(1);
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// If true successor is next block in list, invert the condition. We avoid extra branching by
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// making the true side the fallthrough (i.e, convert it to the false side).
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if (trueSucc == block.ListNext)
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{
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Comparison comp = (Comparison)branchOp.GetSource(2).AsInt32();
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Comparison compInv = comp.Invert();
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branchOp.SetSource(2, Const((int)compInv));
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block.SetSuccessor(0, trueSucc);
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block.SetSuccessor(1, falseSucc);
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update = true;
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}
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}
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}
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if (update)
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{
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cfg.Update(removeUnreachableBlocks: false);
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}
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}
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}
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}
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