Relax block ordering constraints (#1535)
* Relax block ordering constraints Before `block.Next` had to follow `block.ListNext`, now it does not. Instead `CodeGenerator` will now emit the necessary jump instructions to ensure control flow. This makes control flow and block order modifications easier. It also eliminates some simple cases of redundant branches. * Set PPTC version
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3d055da5fc
commit
36ec1bc6c0
11 changed files with 164 additions and 174 deletions
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@ -427,18 +427,5 @@ namespace ARMeilleure.CodeGen.RegisterAllocators
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{
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return local.Assignments.Count + local.Uses.Count;
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}
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private static IEnumerable<BasicBlock> Successors(BasicBlock block)
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{
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if (block.Next != null)
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{
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yield return block.Next;
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}
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if (block.Branch != null)
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{
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yield return block.Branch;
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}
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}
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}
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}
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@ -626,16 +626,11 @@ namespace ARMeilleure.CodeGen.RegisterAllocators
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continue;
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}
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bool hasSingleOrNoSuccessor = block.Next == null || block.Branch == null;
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bool hasSingleOrNoSuccessor = block.SuccessorCount <= 1;
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for (int i = 0; i < 2; i++)
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for (int i = 0; i < block.SuccessorCount; i++)
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{
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// This used to use an enumerable, but it ended up generating a lot of garbage, so now it is a loop.
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BasicBlock successor = (i == 0) ? block.Next : block.Branch;
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if (successor == null)
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{
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continue;
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}
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BasicBlock successor = block.GetSuccessor(i);
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int succIndex = successor.Index;
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@ -643,7 +638,7 @@ namespace ARMeilleure.CodeGen.RegisterAllocators
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// (the successor before the split) should be right after it.
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if (IsSplitEdgeBlock(successor))
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{
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succIndex = FirstSuccessor(successor).Index;
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succIndex = successor.GetSuccessor(0).Index;
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}
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CopyResolver copyResolver = new CopyResolver();
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@ -883,10 +878,11 @@ namespace ARMeilleure.CodeGen.RegisterAllocators
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BitMap liveOut = blkLiveOut[block.Index];
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if ((block.Next != null && liveOut.Set(blkLiveIn[block.Next.Index])) ||
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(block.Branch != null && liveOut.Set(blkLiveIn[block.Branch.Index])))
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for (int i = 0; i < block.SuccessorCount; i++)
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{
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modified = true;
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BasicBlock succ = block.GetSuccessor(i);
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modified |= liveOut.Set(blkLiveIn[succ.Index]);
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}
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BitMap liveIn = blkLiveIn[block.Index];
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@ -1002,11 +998,6 @@ namespace ARMeilleure.CodeGen.RegisterAllocators
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return (register.Index << 1) | (register.Type == RegisterType.Vector ? 1 : 0);
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}
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private static BasicBlock FirstSuccessor(BasicBlock block)
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{
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return block.Next ?? block.Branch;
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}
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private static IEnumerable<Node> BottomOperations(BasicBlock block)
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{
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Node node = block.Operations.Last;
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@ -32,7 +32,6 @@ namespace ARMeilleure.CodeGen.X86
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Add(Instruction.BitwiseExclusiveOr, GenerateBitwiseExclusiveOr);
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Add(Instruction.BitwiseNot, GenerateBitwiseNot);
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Add(Instruction.BitwiseOr, GenerateBitwiseOr);
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Add(Instruction.Branch, GenerateBranch);
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Add(Instruction.BranchIf, GenerateBranchIf);
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Add(Instruction.ByteSwap, GenerateByteSwap);
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Add(Instruction.Call, GenerateCall);
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@ -168,6 +167,23 @@ namespace ARMeilleure.CodeGen.X86
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GenerateOperation(context, operation);
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}
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}
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if (block.SuccessorCount == 0)
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{
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// The only blocks which can have 0 successors are exit blocks.
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Debug.Assert(block.Operations.Last is Operation operation &&
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(operation.Instruction == Instruction.Tailcall ||
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operation.Instruction == Instruction.Return));
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}
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else
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{
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BasicBlock succ = block.GetSuccessor(0);
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if (succ != block.ListNext)
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{
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context.JumpTo(succ);
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}
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}
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}
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Logger.EndPass(PassName.CodeGeneration);
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@ -512,11 +528,6 @@ namespace ARMeilleure.CodeGen.X86
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context.Assembler.Or(dest, src2, dest.Type);
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}
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private static void GenerateBranch(CodeGenContext context, Operation operation)
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{
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context.JumpTo(context.CurrBlock.Branch);
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}
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private static void GenerateBranchIf(CodeGenContext context, Operation operation)
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{
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Operand comp = operation.GetSource(2);
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@ -527,7 +538,7 @@ namespace ARMeilleure.CodeGen.X86
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GenerateCompareCommon(context, operation);
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context.JumpTo(cond, context.CurrBlock.Branch);
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context.JumpTo(cond, context.CurrBlock.GetSuccessor(1));
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}
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private static void GenerateByteSwap(CodeGenContext context, Operation operation)
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@ -57,17 +57,20 @@ namespace ARMeilleure.Diagnostics
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{
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DumpBlockName(block);
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if (block.Next != null)
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if (block.SuccessorCount > 0)
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{
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_builder.Append(" (next ");
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DumpBlockName(block.Next);
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_builder.Append(')');
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}
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_builder.Append(" (");
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for (int i = 0; i < block.SuccessorCount; i++)
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{
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DumpBlockName(block.GetSuccessor(i));
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if (i < block.SuccessorCount - 1)
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{
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_builder.Append(", ");
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}
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}
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if (block.Branch != null)
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{
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_builder.Append(" (branch ");
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DumpBlockName(block.Branch);
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_builder.Append(')');
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}
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@ -1,9 +1,12 @@
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using System;
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using System.Collections.Generic;
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namespace ARMeilleure.IntermediateRepresentation
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{
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class BasicBlock : IIntrusiveListNode<BasicBlock>
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{
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private readonly List<BasicBlock> _successors = new List<BasicBlock>();
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public int Index { get; set; }
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public BasicBlock ListPrevious { get; set; }
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@ -11,69 +14,82 @@ namespace ARMeilleure.IntermediateRepresentation
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public IntrusiveList<Node> Operations { get; }
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private BasicBlock _next;
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private BasicBlock _branch;
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public BasicBlock Next
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{
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get => _next;
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set => _next = AddSuccessor(_next, value);
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}
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public BasicBlock Branch
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{
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get => _branch;
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set => _branch = AddSuccessor(_branch, value);
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}
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public List<BasicBlock> Predecessors { get; }
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public HashSet<BasicBlock> DominanceFrontiers { get; }
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public BasicBlock ImmediateDominator { get; set; }
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public BasicBlock()
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public int SuccessorCount => _successors.Count;
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public BasicBlock() : this(index: -1) { }
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public BasicBlock(int index)
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{
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Operations = new IntrusiveList<Node>();
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Predecessors = new List<BasicBlock>();
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DominanceFrontiers = new HashSet<BasicBlock>();
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Index = -1;
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}
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public BasicBlock(int index) : this()
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{
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Index = index;
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}
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private BasicBlock AddSuccessor(BasicBlock oldBlock, BasicBlock newBlock)
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public void AddSuccessor(BasicBlock block)
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{
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oldBlock?.Predecessors.Remove(this);
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newBlock?.Predecessors.Add(this);
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if (block == null)
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{
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throw new ArgumentNullException(nameof(block));
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}
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return newBlock;
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block.Predecessors.Add(this);
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_successors.Add(block);
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}
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public void RemoveSuccessor(int index)
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{
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BasicBlock oldBlock = _successors[index];
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oldBlock.Predecessors.Remove(this);
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_successors.RemoveAt(index);
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}
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public BasicBlock GetSuccessor(int index)
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{
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return _successors[index];
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}
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public void SetSuccessor(int index, BasicBlock block)
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{
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if (block == null)
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{
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throw new ArgumentNullException(nameof(block));
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}
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BasicBlock oldBlock = _successors[index];
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oldBlock.Predecessors.Remove(this);
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block.Predecessors.Add(this);
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_successors[index] = block;
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}
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public void Append(Node node)
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{
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// If the branch block is not null, then the list of operations
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// should end with a branch instruction. We insert the new operation
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// before this branch.
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if (_branch != null || (Operations.Last != null && IsLeafBlock()))
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{
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Operations.AddBefore(Operations.Last, node);
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}
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else
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{
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Operations.AddLast(node);
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}
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}
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var lastOp = Operations.Last as Operation;
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private bool IsLeafBlock()
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{
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return _branch == null && _next == null;
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// Append node before terminal or to end if no terminal.
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switch (lastOp?.Instruction)
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{
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case Instruction.Return:
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case Instruction.Tailcall:
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case Instruction.BranchIf:
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Operations.AddBefore(lastOp, node);
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break;
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default:
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Operations.AddLast(node);
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break;
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}
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}
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public Node GetLastOp()
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@ -7,7 +7,6 @@ namespace ARMeilleure.IntermediateRepresentation
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BitwiseExclusiveOr,
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BitwiseNot,
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BitwiseOr,
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Branch,
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BranchIf,
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ByteSwap,
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Call,
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@ -8,47 +8,48 @@ namespace ARMeilleure.Translation
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class ControlFlowGraph
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{
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public BasicBlock Entry { get; }
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public IntrusiveList<BasicBlock> Blocks { get; }
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public BasicBlock[] PostOrderBlocks { get; }
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public int[] PostOrderMap { get; }
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public ControlFlowGraph(BasicBlock entry, IntrusiveList<BasicBlock> blocks)
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{
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Entry = entry;
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Entry = entry;
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Blocks = blocks;
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RemoveUnreachableBlocks(blocks);
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HashSet<BasicBlock> visited = new HashSet<BasicBlock>();
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Stack<BasicBlock> blockStack = new Stack<BasicBlock>();
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var visited = new HashSet<BasicBlock>();
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var blockStack = new Stack<BasicBlock>();
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PostOrderBlocks = new BasicBlock[blocks.Count];
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PostOrderMap = new int[blocks.Count];
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visited.Add(entry);
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blockStack.Push(entry);
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int index = 0;
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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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bool visitedNew = false;
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for (int i = 0; i < block.SuccessorCount; i++)
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{
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blockStack.Push(block);
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blockStack.Push(block.Next);
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BasicBlock succ = block.GetSuccessor(i);
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if (visited.Add(succ))
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{
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blockStack.Push(block);
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blockStack.Push(succ);
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visitedNew = true;
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break;
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}
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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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if (!visitedNew)
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{
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PostOrderMap[block.Index] = index;
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@ -59,26 +60,24 @@ namespace ARMeilleure.Translation
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private void RemoveUnreachableBlocks(IntrusiveList<BasicBlock> blocks)
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{
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HashSet<BasicBlock> visited = new HashSet<BasicBlock>();
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Queue<BasicBlock> workQueue = new Queue<BasicBlock>();
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var visited = new HashSet<BasicBlock>();
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var workQueue = new Queue<BasicBlock>();
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visited.Add(Entry);
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workQueue.Enqueue(Entry);
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while (workQueue.TryDequeue(out BasicBlock block))
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{
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Debug.Assert(block.Index != -1, "Invalid block index.");
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if (block.Next != null && visited.Add(block.Next))
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for (int i = 0; i < block.SuccessorCount; i++)
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{
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workQueue.Enqueue(block.Next);
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}
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BasicBlock succ = block.GetSuccessor(i);
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if (block.Branch != null && visited.Add(block.Branch))
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{
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workQueue.Enqueue(block.Branch);
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if (visited.Add(succ))
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{
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workQueue.Enqueue(succ);
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}
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}
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}
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@ -93,8 +92,10 @@ namespace ARMeilleure.Translation
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if (!visited.Contains(block))
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{
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block.Next = null;
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block.Branch = null;
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while (block.SuccessorCount > 0)
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{
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block.RemoveSuccessor(index: block.SuccessorCount - 1);
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}
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blocks.Remove(block);
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}
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@ -112,14 +113,12 @@ namespace ARMeilleure.Translation
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{
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BasicBlock splitBlock = new BasicBlock(Blocks.Count);
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if (predecessor.Next == successor)
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for (int i = 0; i < predecessor.SuccessorCount; i++)
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{
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predecessor.Next = splitBlock;
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}
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if (predecessor.Branch == successor)
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{
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predecessor.Branch = splitBlock;
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if (predecessor.GetSuccessor(i) == successor)
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{
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predecessor.SetSuccessor(i, splitBlock);
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}
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}
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if (splitBlock.Predecessors.Count == 0)
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@ -127,26 +126,7 @@ namespace ARMeilleure.Translation
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throw new ArgumentException("Predecessor and successor are not connected.");
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}
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// Insert the new block on the list of blocks.
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BasicBlock succPrev = successor.ListPrevious;
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if (succPrev != null && succPrev != predecessor && succPrev.Next == successor)
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{
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// Can't insert after the predecessor or before the successor.
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// Here, we insert it before the successor by also spliting another
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// edge (the one between the block before "successor" and "successor").
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BasicBlock splitBlock2 = new BasicBlock(splitBlock.Index + 1);
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succPrev.Next = splitBlock2;
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splitBlock2.Branch = successor;
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splitBlock2.Operations.AddLast(OperationHelper.Operation(Instruction.Branch, null));
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Blocks.AddBefore(successor, splitBlock2);
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}
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splitBlock.Next = successor;
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splitBlock.AddSuccessor(successor);
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Blocks.AddBefore(successor, splitBlock);
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@ -13,18 +13,17 @@ namespace ARMeilleure.Translation
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class EmitterContext
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{
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private Dictionary<Operand, BasicBlock> _irLabels;
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private IntrusiveList<BasicBlock> _irBlocks;
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private readonly Dictionary<Operand, BasicBlock> _irLabels;
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private readonly IntrusiveList<BasicBlock> _irBlocks;
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private BasicBlock _irBlock;
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private BasicBlock _ifBlock;
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private bool _needsNewBlock;
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public EmitterContext()
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{
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_irLabels = new Dictionary<Operand, BasicBlock>();
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_irBlocks = new IntrusiveList<BasicBlock>();
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_needsNewBlock = true;
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@ -57,16 +56,16 @@ namespace ARMeilleure.Translation
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public void Branch(Operand label)
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{
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Add(Instruction.Branch, null);
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NewNextBlockIfNeeded();
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BranchToLabel(label);
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BranchToLabel(label, uncond: true);
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}
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public void BranchIf(Operand label, Operand op1, Operand op2, Comparison comp)
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{
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Add(Instruction.BranchIf, null, op1, op2, Const((int)comp));
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BranchToLabel(label);
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BranchToLabel(label, uncond: false);
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}
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public void BranchIfFalse(Operand label, Operand op1)
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@ -574,10 +573,7 @@ namespace ARMeilleure.Translation
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private Operand Add(Intrinsic intrin, Operand dest, params Operand[] sources)
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{
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if (_needsNewBlock)
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{
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NewNextBlock();
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}
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NewNextBlockIfNeeded();
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IntrinsicOperation operation = new IntrinsicOperation(intrin, dest, sources);
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@ -586,7 +582,7 @@ namespace ARMeilleure.Translation
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return dest;
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}
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private void BranchToLabel(Operand label)
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private void BranchToLabel(Operand label, bool uncond)
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{
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if (!_irLabels.TryGetValue(label, out BasicBlock branchBlock))
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{
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||||
|
@ -595,7 +591,15 @@ namespace ARMeilleure.Translation
|
|||
_irLabels.Add(label, branchBlock);
|
||||
}
|
||||
|
||||
_irBlock.Branch = branchBlock;
|
||||
if (uncond)
|
||||
{
|
||||
_irBlock.AddSuccessor(branchBlock);
|
||||
}
|
||||
else
|
||||
{
|
||||
// Defer registration of successor to _irBlock so that the order of successors is correct.
|
||||
_ifBlock = branchBlock;
|
||||
}
|
||||
|
||||
_needsNewBlock = true;
|
||||
}
|
||||
|
@ -629,9 +633,16 @@ namespace ARMeilleure.Translation
|
|||
|
||||
private void NextBlock(BasicBlock nextBlock)
|
||||
{
|
||||
if (_irBlock != null && !EndsWithUnconditional(_irBlock))
|
||||
if (_irBlock != null && _irBlock.SuccessorCount == 0 && !EndsWithUnconditional(_irBlock))
|
||||
{
|
||||
_irBlock.Next = nextBlock;
|
||||
_irBlock.AddSuccessor(nextBlock);
|
||||
|
||||
if (_ifBlock != null)
|
||||
{
|
||||
_irBlock.AddSuccessor(_ifBlock);
|
||||
|
||||
_ifBlock = null;
|
||||
}
|
||||
}
|
||||
|
||||
_irBlock = nextBlock;
|
||||
|
@ -642,8 +653,7 @@ namespace ARMeilleure.Translation
|
|||
private static bool EndsWithUnconditional(BasicBlock block)
|
||||
{
|
||||
return block.Operations.Last is Operation lastOp &&
|
||||
(lastOp.Instruction == Instruction.Branch ||
|
||||
lastOp.Instruction == Instruction.Return ||
|
||||
(lastOp.Instruction == Instruction.Return ||
|
||||
lastOp.Instruction == Instruction.Tailcall);
|
||||
}
|
||||
|
||||
|
|
|
@ -21,7 +21,7 @@ namespace ARMeilleure.Translation.PTC
|
|||
{
|
||||
private const string HeaderMagic = "PTChd";
|
||||
|
||||
private const int InternalVersion = 1537; //! To be incremented manually for each change to the ARMeilleure project.
|
||||
private const int InternalVersion = 1535; //! To be incremented manually for each change to the ARMeilleure project.
|
||||
|
||||
private const string ActualDir = "0";
|
||||
private const string BackupDir = "1";
|
||||
|
|
|
@ -171,14 +171,9 @@ namespace ARMeilleure.Translation
|
|||
|
||||
RegisterMask inputs = localInputs[block.Index];
|
||||
|
||||
if (block.Next != null)
|
||||
for (int i = 0; i < block.SuccessorCount; i++)
|
||||
{
|
||||
inputs |= globalInputs[block.Next.Index];
|
||||
}
|
||||
|
||||
if (block.Branch != null)
|
||||
{
|
||||
inputs |= globalInputs[block.Branch.Index];
|
||||
inputs |= globalInputs[block.GetSuccessor(i).Index];
|
||||
}
|
||||
|
||||
inputs &= ~globalCmnOutputs[block.Index];
|
||||
|
|
|
@ -309,8 +309,6 @@ namespace ARMeilleure.Translation
|
|||
|
||||
context.Return(Const(0L));
|
||||
|
||||
context.Branch(lblExit);
|
||||
|
||||
context.MarkLabel(lblNonZero);
|
||||
|
||||
count = context.Subtract(count, Const(1));
|
||||
|
|
Loading…
Reference in a new issue