Optimize blocks #919
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,165 +1,161 @@ | ||
| #nullable enable | ||
|
|
||
| using System.Collections.Generic; | ||
| using System.Diagnostics.Contracts; | ||
| using System.Linq; | ||
|
|
||
| namespace Microsoft.Boogie; | ||
|
|
||
| public class BlockCoalescer : ReadOnlyVisitor | ||
| { | ||
| public static void CoalesceBlocks(Program program) | ||
| { | ||
| var blockCoalescer = new BlockCoalescer(); | ||
| blockCoalescer.Visit(program); | ||
| } | ||
|
|
||
| private static HashSet<Block> ComputeMultiPredecessorBlocks(Block rootBlock) | ||
| { | ||
| Contract.Ensures(cce.NonNullElements(Contract.Result<HashSet<Block>>())); | ||
| var visitedBlocks = new HashSet<Block /*!*/>(); | ||
| var result = new HashSet<Block>(); | ||
| var dfsStack = new Stack<Block>(); | ||
| dfsStack.Push(rootBlock); | ||
| while (dfsStack.Count > 0) | ||
| { | ||
| var /*!*/ block = dfsStack.Pop(); | ||
| Contract.Assert(block != null); | ||
| if (!visitedBlocks.Add(block)) | ||
| { | ||
| result.Add(block); | ||
| continue; | ||
| } | ||
|
|
||
| if (block.TransferCmd == null) | ||
| { | ||
| continue; | ||
| } | ||
|
|
||
| if (block.TransferCmd is ReturnCmd) | ||
| { | ||
| continue; | ||
| } | ||
|
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||
| Contract.Assert(block.TransferCmd is GotoCmd); | ||
| var gotoCmd = (GotoCmd) block.TransferCmd; | ||
| if (gotoCmd.labelTargets == null) | ||
| { | ||
| continue; | ||
| } | ||
|
|
||
| foreach (var /*!*/ succ in gotoCmd.labelTargets) | ||
| { | ||
| Contract.Assert(succ != null); | ||
| dfsStack.Push(succ); | ||
| } | ||
| } | ||
|
|
||
| return result; | ||
| } | ||
|
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| public override Implementation VisitImplementation(Implementation impl) | ||
| { | ||
| var newBlocks = CoalesceFromRootBlock(impl.Blocks); | ||
| impl.Blocks = newBlocks; | ||
| foreach (var block in impl.Blocks) | ||
| { | ||
| if (block.TransferCmd is ReturnCmd) | ||
| { | ||
| continue; | ||
| } | ||
|
|
||
| var gotoCmd = (GotoCmd)block.TransferCmd; | ||
| gotoCmd.labelNames = new List<string>(); | ||
| foreach (var successor in gotoCmd.labelTargets) | ||
| { | ||
| gotoCmd.labelNames.Add(successor.Label); | ||
| } | ||
| } | ||
| return impl; | ||
| } | ||
|
|
||
| public static List<Block> CoalesceFromRootBlock(List<Block> blocks) | ||
| { | ||
| if (!blocks.Any()) | ||
| { | ||
| return blocks; | ||
| } | ||
| var multiPredecessorBlocks = ComputeMultiPredecessorBlocks(blocks[0]); | ||
| Contract.Assert(cce.NonNullElements(multiPredecessorBlocks)); | ||
| var visitedBlocks = new HashSet<Block>(); | ||
| var removedBlocks = new HashSet<Block>(); | ||
| var toVisit = new Stack<Block>(); | ||
| toVisit.Push(blocks[0]); | ||
| while (toVisit.Count > 0) | ||
| { | ||
| var block = toVisit.Pop(); | ||
| Contract.Assert(block != null); | ||
| if (!visitedBlocks.Add(block)) | ||
| { | ||
| continue; | ||
| } | ||
|
|
||
| if (block.TransferCmd == null) | ||
| { | ||
| continue; | ||
| } | ||
|
|
||
| if (block.TransferCmd is ReturnCmd) | ||
| { | ||
| continue; | ||
| } | ||
|
|
||
| Contract.Assert(block.TransferCmd is GotoCmd); | ||
| var gotoCmd = (GotoCmd) block.TransferCmd; | ||
| if (gotoCmd.labelTargets == null) | ||
| { | ||
| continue; | ||
| } | ||
|
|
||
| if (gotoCmd.labelTargets.Count != 1) | ||
| { | ||
| foreach (var aSuccessor in gotoCmd.labelTargets) | ||
| { | ||
| Contract.Assert(aSuccessor != null); | ||
| toVisit.Push(aSuccessor); | ||
| } | ||
| continue; | ||
| } | ||
|
|
||
| var successor = cce.NonNull(gotoCmd.labelTargets[0]); | ||
| if (multiPredecessorBlocks.Contains(successor)) | ||
| { | ||
| toVisit.Push(successor); | ||
| continue; | ||
| } | ||
|
|
||
| block.Cmds.AddRange(successor.Cmds); | ||
| block.TransferCmd = successor.TransferCmd; | ||
| if (!block.tok.IsValid && successor.tok.IsValid) | ||
| { | ||
| block.tok = successor.tok; | ||
| block.Label = successor.Label; | ||
| } | ||
|
|
||
| removedBlocks.Add(successor); | ||
| toVisit.Push(block); | ||
| visitedBlocks.Remove(block); | ||
| } | ||
|
|
||
| var newBlocks = new List<Block>(); | ||
| foreach (var block in blocks) | ||
| { | ||
| Contract.Assert(block != null); | ||
| if (visitedBlocks.Contains(block) && !removedBlocks.Contains(block)) | ||
| { | ||
| newBlocks.Add(block); | ||
| } | ||
| } | ||
| return newBlocks; | ||
| } | ||
| } |
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You've added some trailing whitespace here. I find that Rider is very eager to do this!