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Implement block placement (#1549)

* Implement block placement

Implement a simple pass which re-orders cold blocks at the end of the
list of blocks in the CFG.

* Set PPTC version

* Use Array.Resize

Address gdkchan's feedback
This commit is contained in:
FICTURE7 2020-09-20 03:00:24 +04:00 committed by GitHub
parent 1eea35554c
commit f60033e0aa
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 136 additions and 31 deletions

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@ -0,0 +1,66 @@
using ARMeilleure.IntermediateRepresentation;
using ARMeilleure.Translation;
using System.Diagnostics;
using static ARMeilleure.IntermediateRepresentation.OperandHelper;
namespace ARMeilleure.CodeGen.Optimizations
{
static class BlockPlacement
{
public static void RunPass(ControlFlowGraph cfg)
{
bool update = false;
BasicBlock block;
BasicBlock nextBlock;
BasicBlock lastBlock = cfg.Blocks.Last;
// Move cold blocks at the end of the list, so that they are emitted away from hot code.
for (block = cfg.Blocks.First; block != lastBlock; block = nextBlock)
{
nextBlock = block.ListNext;
if (block.Frequency == BasicBlockFrequency.Cold)
{
cfg.Blocks.Remove(block);
cfg.Blocks.AddLast(block);
}
}
for (block = cfg.Blocks.First; block != null; block = nextBlock)
{
nextBlock = block.ListNext;
if (block.SuccessorCount == 2 && block.Operations.Last is Operation branchOp)
{
Debug.Assert(branchOp.Instruction == Instruction.BranchIf);
BasicBlock falseSucc = block.GetSuccessor(0);
BasicBlock trueSucc = block.GetSuccessor(1);
// If true successor is next block in list, invert the condition. We avoid extra branching by
// making the true side the fallthrough (i.e, convert it to the false side).
if (trueSucc == block.ListNext)
{
Comparison comp = (Comparison)branchOp.GetSource(2).AsInt32();
Comparison compInv = comp.Invert();
branchOp.SetSource(2, Const((int)compInv));
block.SetSuccessor(0, trueSucc);
block.SetSuccessor(1, falseSucc);
update = true;
}
}
}
if (update)
{
cfg.Update(removeUnreachableBlocks: false);
}
}
}
}

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@ -106,6 +106,8 @@ namespace ARMeilleure.CodeGen.X86
X86Optimizer.RunPass(cfg);
BlockPlacement.RunPass(cfg);
Logger.EndPass(PassName.Optimization, cfg);
Logger.StartPass(PassName.PreAllocation);
@ -186,9 +188,11 @@ namespace ARMeilleure.CodeGen.X86
}
}
byte[] code = context.GetCode();
Logger.EndPass(PassName.CodeGeneration);
return new CompiledFunction(context.GetCode(), unwindInfo);
return new CompiledFunction(code, unwindInfo);
}
}

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@ -57,6 +57,11 @@ namespace ARMeilleure.Diagnostics
{
DumpBlockName(block);
if (block.Frequency == BasicBlockFrequency.Cold)
{
_builder.Append(" cold");
}
if (block.SuccessorCount > 0)
{
_builder.Append(" (");

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@ -174,7 +174,7 @@ namespace ARMeilleure.Instructions
Operand lblContinue = context.GetLabel(nextAddr.Value);
// We need to clear out the call flag for the return address before comparing it.
context.BranchIf(lblContinue, context.BitwiseAnd(returnAddress, Const(~CallFlag)), nextAddr, Comparison.Equal);
context.BranchIf(lblContinue, context.BitwiseAnd(returnAddress, Const(~CallFlag)), nextAddr, Comparison.Equal, BasicBlockFrequency.Cold);
context.Return(returnAddress);
}

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@ -147,7 +147,7 @@ namespace ARMeilleure.Instructions
context.Branch(lblEnd);
context.MarkLabel(lblSlowPath);
context.MarkLabel(lblSlowPath, BasicBlockFrequency.Cold);
EmitReadIntFallback(context, address, rt, size);
@ -165,7 +165,7 @@ namespace ARMeilleure.Instructions
Operand lblFastPath = Label();
context.BranchIfFalse(lblFastPath, isUnalignedAddr);
context.BranchIfFalse(lblFastPath, isUnalignedAddr, BasicBlockFrequency.Cold);
// The call is not expected to return (it should throw).
context.Call(typeof(NativeInterface).GetMethod(nameof(NativeInterface.ThrowInvalidMemoryAccess)), address);
@ -216,7 +216,7 @@ namespace ARMeilleure.Instructions
context.Branch(lblEnd);
context.MarkLabel(lblSlowPath);
context.MarkLabel(lblSlowPath, BasicBlockFrequency.Cold);
EmitReadVectorFallback(context, address, vector, rt, elem, size);
@ -256,7 +256,7 @@ namespace ARMeilleure.Instructions
context.Branch(lblEnd);
context.MarkLabel(lblSlowPath);
context.MarkLabel(lblSlowPath, BasicBlockFrequency.Cold);
EmitWriteIntFallback(context, address, rt, size);
@ -274,7 +274,7 @@ namespace ARMeilleure.Instructions
Operand lblFastPath = Label();
context.BranchIfFalse(lblFastPath, isUnalignedAddr);
context.BranchIfFalse(lblFastPath, isUnalignedAddr, BasicBlockFrequency.Cold);
// The call is not expected to return (it should throw).
context.Call(typeof(NativeInterface).GetMethod(nameof(NativeInterface.ThrowInvalidMemoryAccess)), address);
@ -331,7 +331,7 @@ namespace ARMeilleure.Instructions
context.Branch(lblEnd);
context.MarkLabel(lblSlowPath);
context.MarkLabel(lblSlowPath, BasicBlockFrequency.Cold);
EmitWriteVectorFallback(context, address, rt, elem, size);
@ -402,7 +402,7 @@ namespace ARMeilleure.Instructions
Operand lblNotWatched = Label();
// Is the page currently being monitored for modifications? If so we need to call MarkRegionAsModified.
context.BranchIf(lblNotWatched, pte, Const(0L), Comparison.GreaterOrEqual);
context.BranchIf(lblNotWatched, pte, Const(0L), Comparison.GreaterOrEqual, BasicBlockFrequency.Cold);
// Mark the region as modified. Size here doesn't matter as address is assumed to be size aligned here.
context.Call(typeof(NativeInterface).GetMethod(nameof(NativeInterface.MarkRegionAsModified)), address, Const(1UL));
@ -412,7 +412,7 @@ namespace ARMeilleure.Instructions
Operand lblNonNull = Label();
// Skip exception if the PTE address is non-null (not zero).
context.BranchIfTrue(lblNonNull, pte);
context.BranchIfTrue(lblNonNull, pte, BasicBlockFrequency.Cold);
// The call is not expected to return (it should throw).
context.Call(typeof(NativeInterface).GetMethod(nameof(NativeInterface.ThrowInvalidMemoryAccess)), address);

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@ -5,10 +5,12 @@ namespace ARMeilleure.IntermediateRepresentation
{
class BasicBlock : IIntrusiveListNode<BasicBlock>
{
private readonly List<BasicBlock> _successors = new List<BasicBlock>();
private readonly List<BasicBlock> _successors;
public int Index { get; set; }
public BasicBlockFrequency Frequency { get; set; }
public BasicBlock ListPrevious { get; set; }
public BasicBlock ListNext { get; set; }
@ -25,6 +27,8 @@ namespace ARMeilleure.IntermediateRepresentation
public BasicBlock(int index)
{
_successors = new List<BasicBlock>();
Operations = new IntrusiveList<Node>();
Predecessors = new List<BasicBlock>();
DominanceFrontiers = new HashSet<BasicBlock>();

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@ -0,0 +1,8 @@
namespace ARMeilleure.IntermediateRepresentation
{
enum BasicBlockFrequency
{
Default,
Cold
}
}

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@ -7,26 +7,37 @@ namespace ARMeilleure.Translation
{
class ControlFlowGraph
{
private BasicBlock[] _postOrderBlocks;
private int[] _postOrderMap;
public BasicBlock Entry { get; }
public IntrusiveList<BasicBlock> Blocks { get; }
public BasicBlock[] PostOrderBlocks { get; }
public int[] PostOrderMap { get; }
public BasicBlock[] PostOrderBlocks => _postOrderBlocks;
public int[] PostOrderMap => _postOrderMap;
public ControlFlowGraph(BasicBlock entry, IntrusiveList<BasicBlock> blocks)
{
Entry = entry;
Blocks = blocks;
RemoveUnreachableBlocks(blocks);
Update(removeUnreachableBlocks: true);
}
public void Update(bool removeUnreachableBlocks)
{
if (removeUnreachableBlocks)
{
RemoveUnreachableBlocks(Blocks);
}
var visited = new HashSet<BasicBlock>();
var blockStack = new Stack<BasicBlock>();
PostOrderBlocks = new BasicBlock[blocks.Count];
PostOrderMap = new int[blocks.Count];
Array.Resize(ref _postOrderBlocks, Blocks.Count);
Array.Resize(ref _postOrderMap, Blocks.Count);
visited.Add(entry);
blockStack.Push(entry);
visited.Add(Entry);
blockStack.Push(Entry);
int index = 0;

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@ -20,6 +20,7 @@ namespace ARMeilleure.Translation
private BasicBlock _ifBlock;
private bool _needsNewBlock;
private BasicBlockFrequency _nextBlockFreq;
public EmitterContext()
{
@ -27,6 +28,7 @@ namespace ARMeilleure.Translation
_irBlocks = new IntrusiveList<BasicBlock>();
_needsNewBlock = true;
_nextBlockFreq = BasicBlockFrequency.Default;
}
public Operand Add(Operand op1, Operand op2)
@ -58,24 +60,24 @@ namespace ARMeilleure.Translation
{
NewNextBlockIfNeeded();
BranchToLabel(label, uncond: true);
BranchToLabel(label, uncond: true, BasicBlockFrequency.Default);
}
public void BranchIf(Operand label, Operand op1, Operand op2, Comparison comp)
public void BranchIf(Operand label, Operand op1, Operand op2, Comparison comp, BasicBlockFrequency falseFreq = default)
{
Add(Instruction.BranchIf, null, op1, op2, Const((int)comp));
BranchToLabel(label, uncond: false);
BranchToLabel(label, uncond: false, falseFreq);
}
public void BranchIfFalse(Operand label, Operand op1)
public void BranchIfFalse(Operand label, Operand op1, BasicBlockFrequency falseFreq = default)
{
BranchIf(label, op1, Const(op1.Type, 0), Comparison.Equal);
BranchIf(label, op1, Const(op1.Type, 0), Comparison.Equal, falseFreq);
}
public void BranchIfTrue(Operand label, Operand op1)
public void BranchIfTrue(Operand label, Operand op1, BasicBlockFrequency falseFreq = default)
{
BranchIf(label, op1, Const(op1.Type, 0), Comparison.NotEqual);
BranchIf(label, op1, Const(op1.Type, 0), Comparison.NotEqual, falseFreq);
}
public Operand ByteSwap(Operand op1)
@ -582,7 +584,7 @@ namespace ARMeilleure.Translation
return dest;
}
private void BranchToLabel(Operand label, bool uncond)
private void BranchToLabel(Operand label, bool uncond, BasicBlockFrequency nextFreq)
{
if (!_irLabels.TryGetValue(label, out BasicBlock branchBlock))
{
@ -602,10 +604,13 @@ namespace ARMeilleure.Translation
}
_needsNewBlock = true;
_nextBlockFreq = nextFreq;
}
public void MarkLabel(Operand label)
public void MarkLabel(Operand label, BasicBlockFrequency nextFreq = default)
{
_nextBlockFreq = nextFreq;
if (_irLabels.TryGetValue(label, out BasicBlock nextBlock))
{
nextBlock.Index = _irBlocks.Count;
@ -633,7 +638,7 @@ namespace ARMeilleure.Translation
private void NextBlock(BasicBlock nextBlock)
{
if (_irBlock != null && _irBlock.SuccessorCount == 0 && !EndsWithUnconditional(_irBlock))
if (_irBlock?.SuccessorCount == 0 && !EndsWithUnconditional(_irBlock))
{
_irBlock.AddSuccessor(nextBlock);
@ -646,8 +651,10 @@ namespace ARMeilleure.Translation
}
_irBlock = nextBlock;
_irBlock.Frequency = _nextBlockFreq;
_needsNewBlock = false;
_nextBlockFreq = BasicBlockFrequency.Default;
}
private static bool EndsWithUnconditional(BasicBlock block)

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@ -21,7 +21,7 @@ namespace ARMeilleure.Translation.PTC
{
private const string HeaderMagic = "PTChd";
private const int InternalVersion = 1535; //! To be incremented manually for each change to the ARMeilleure project.
private const int InternalVersion = 1549; //! To be incremented manually for each change to the ARMeilleure project.
private const string ActualDir = "0";
private const string BackupDir = "1";

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@ -301,11 +301,11 @@ namespace ARMeilleure.Translation
Operand lblNonZero = Label();
Operand lblExit = Label();
context.BranchIfTrue(lblNonZero, count);
context.BranchIfTrue(lblNonZero, count, BasicBlockFrequency.Cold);
Operand running = context.Call(typeof(NativeInterface).GetMethod(nameof(NativeInterface.CheckSynchronization)));
context.BranchIfTrue(lblExit, running);
context.BranchIfTrue(lblExit, running, BasicBlockFrequency.Cold);
context.Return(Const(0L));