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Generalize IControlFlowGraph successors #103676

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Jun 26, 2024
Merged

Generalize IControlFlowGraph successors #103676

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7e63048
Generalize IControlFlowGraph successors
sbomer Jun 18, 2024
debed0b
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sbomer Jun 26, 2024
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22 changes: 14 additions & 8 deletions src/tools/illink/src/ILLink.RoslynAnalyzer/DataFlow/ControlFlowGraphProxy.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,11 +55,8 @@ public IEnumerable<BlockProxy> Blocks {

public BlockProxy Entry => new BlockProxy (ControlFlowGraph.EntryBlock ());

public static ControlFlowBranch? CreateProxyBranch (Microsoft.CodeAnalysis.FlowAnalysis.ControlFlowBranch? branch)
public static ControlFlowBranch CreateProxyBranch (Microsoft.CodeAnalysis.FlowAnalysis.ControlFlowBranch branch)
{
if (branch == null)
return null;

var finallyRegions = ImmutableArray.CreateBuilder<RegionProxy> ();
foreach (var region in branch.FinallyRegions) {
Debug.Assert (region != null);
Expand All @@ -73,7 +70,12 @@ public IEnumerable<BlockProxy> Blocks {
new BlockProxy (branch.Source),
branch.Destination == null ? null : new BlockProxy (branch.Destination),
finallyRegions.ToImmutable (),
branch.IsConditionalSuccessor);
branch.Source.ConditionKind switch {
ControlFlowConditionKind.None => ConditionKind.Unconditional,
ControlFlowConditionKind.WhenFalse => branch.IsConditionalSuccessor ? ConditionKind.WhenFalse : ConditionKind.WhenTrue,
ControlFlowConditionKind.WhenTrue => branch.IsConditionalSuccessor ? ConditionKind.WhenTrue : ConditionKind.WhenFalse,
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_ => throw new InvalidOperationException ()
});
}

// This is implemented by getting predecessors of the underlying Roslyn BasicBlock.
Expand All @@ -86,9 +88,13 @@ public IEnumerable<ControlFlowBranch> GetPredecessors (BlockProxy block)
}
}

public ControlFlowBranch? GetConditionalSuccessor (BlockProxy block) => CreateProxyBranch (block.Block.ConditionalSuccessor);

public ControlFlowBranch? GetFallThroughSuccessor (BlockProxy block) => CreateProxyBranch (block.Block.FallThroughSuccessor);
public IEnumerable<ControlFlowBranch> GetSuccessors (BlockProxy block)
{
if (block.Block.ConditionalSuccessor is Microsoft.CodeAnalysis.FlowAnalysis.ControlFlowBranch conditionalSuccessor)
yield return CreateProxyBranch (conditionalSuccessor);
if (block.Block.FallThroughSuccessor is Microsoft.CodeAnalysis.FlowAnalysis.ControlFlowBranch fallThroughSuccessor)
yield return CreateProxyBranch (fallThroughSuccessor);
}

public bool TryGetEnclosingTryOrCatchOrFilter (BlockProxy block, out RegionProxy tryOrCatchOrFilterRegion)
{
Expand Down
41 changes: 13 additions & 28 deletions src/tools/illink/src/ILLink.Shared/DataFlow/ForwardDataFlowAnalysis.cs
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Expand Up @@ -4,6 +4,7 @@
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;

// This is needed due to NativeAOT which doesn't enable nullable globally yet
#nullable enable
Expand Down Expand Up @@ -65,13 +66,12 @@ public ControlFlowGraphState (TControlFlowGraph cfg, TLattice lattice, TValue en
this.cfg = cfg;
this.lattice = lattice;

var entryOut = cfg.GetFallThroughSuccessor (cfg.Entry);
IControlFlowGraph<TBlock, TRegion>.ControlFlowBranch? entryOut = cfg.GetSuccessors (cfg.Entry).SingleOrDefault ();
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Debug.Assert (entryOut != null);
Debug.Assert (cfg.GetConditionalSuccessor (cfg.Entry) == null);
if (entryOut == null)
return;

branchInput[entryOut!.Value] = new TState () {
branchInput[entryOut.Value] = new TState () {
Lattice = lattice,
Current = entryValue,
Exception = null
Expand Down Expand Up @@ -187,35 +187,20 @@ void TransferOut (TTransfer transfer, TControlFlowGraph cfg, TBlock block, TStat
)
{
TConditionValue? conditionValue = transfer.Transfer (block, state);

if (cfg.GetConditionalSuccessor (block) is IControlFlowGraph<TBlock, TRegion>.ControlFlowBranch conditionalBranch) {
// Duplicate the current state so that it's not shared with fall-through state.
TValue conditionalCurrentState = lattice.Meet (lattice.Top, state.Current);

if (conditionValue != null) {
transfer.ApplyCondition (
// ConditionKind 'WhenTrue' means the condition is true in the conditional branch.
block.ConditionKind is ConditionKind.WhenTrue
? conditionValue.Value
: conditionValue.Value.Negate (),
ref conditionalCurrentState);
}

updateState (conditionalBranch, conditionalCurrentState);
}

if (cfg.GetFallThroughSuccessor (block) is IControlFlowGraph<TBlock, TRegion>.ControlFlowBranch fallThroughBranch) {
TValue fallThroughCurrentState = state.Current;
foreach (var successor in cfg.GetSuccessors (block)) {
// Duplicate the state so that it's not shared between branches.
TValue branchState = lattice.Meet (lattice.Top, state.Current);
if (conditionValue != null) {
Debug.Assert (successor.ConditionKind is ConditionKind.WhenTrue or ConditionKind.WhenFalse);
transfer.ApplyCondition (
// ConditionKind 'WhenFalse' means the condition is true in the fall-through branch (false in the conditional branch).
block.ConditionKind is ConditionKind.WhenFalse
// ConditionKind 'WhenTrue' means the condition is true in this branch.
successor.ConditionKind is ConditionKind.WhenTrue
? conditionValue.Value
: conditionValue.Value.Negate (),
ref fallThroughCurrentState);
ref branchState);
}

updateState (fallThroughBranch, fallThroughCurrentState);
updateState (successor, branchState);
}
}

Expand Down Expand Up @@ -423,11 +408,11 @@ void FlowStateThroughExitedFinallys (
changed = true;

TBlock lastFinallyBlock = cfg.LastBlock (exitedFinally);
Debug.Assert (cfg.GetConditionalSuccessor (lastFinallyBlock) == null);
IControlFlowGraph<TBlock, TRegion>.ControlFlowBranch? finallyExit = cfg.GetFallThroughSuccessor (lastFinallyBlock);
IControlFlowGraph<TBlock, TRegion>.ControlFlowBranch? finallyExit = cfg.GetSuccessors (lastFinallyBlock).SingleOrDefault ();
Debug.Assert (finallyExit != null);
if (finallyExit == null)
continue;
Debug.Assert (finallyExit.Value.ConditionKind == ConditionKind.Unconditional);
predecessorState = cfgState.Get (finallyExit.Value).Current;
}
}
Expand Down
22 changes: 12 additions & 10 deletions src/tools/illink/src/ILLink.Shared/DataFlow/IControlFlowGraph.cs
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Expand Up @@ -21,9 +21,10 @@ public enum RegionKind

public enum ConditionKind
{
None,
Unconditional,
WhenFalse,
WhenTrue,
Unknown
}

public interface IRegion<TRegion> : IEquatable<TRegion>
Expand All @@ -33,7 +34,6 @@ public interface IRegion<TRegion> : IEquatable<TRegion>

public interface IBlock<TBlock> : IEquatable<TBlock>
{
ConditionKind ConditionKind { get; }
}

public interface IControlFlowGraph<TBlock, TRegion>
Expand All @@ -45,8 +45,12 @@ public interface IControlFlowGraph<TBlock, TRegion>
public readonly struct ControlFlowBranch : IEquatable<ControlFlowBranch>
{
public readonly TBlock Source;

// Might be null in a 'throw' branch.
public readonly TBlock? Destination;

public readonly ConditionKind ConditionKind;

// The finally regions exited when control flows through this edge.
// For example:
//
Expand All @@ -62,21 +66,21 @@ public interface IControlFlowGraph<TBlock, TRegion>
// Source() to the block that calls Target(), which exits both
// finally regions.
public readonly ImmutableArray<TRegion> FinallyRegions;
public readonly bool IsConditional;
public ControlFlowBranch (TBlock source, TBlock? destination, ImmutableArray<TRegion> finallyRegions, bool isConditional)

public ControlFlowBranch (TBlock source, TBlock? destination, ImmutableArray<TRegion> finallyRegions, ConditionKind conditionKind)
{
Source = source;
Destination = destination;
FinallyRegions = finallyRegions;
IsConditional = isConditional;
ConditionKind = conditionKind;
}

public bool Equals (ControlFlowBranch other)
{
if (!Source.Equals (other.Source))
return false;

if (IsConditional != other.IsConditional)
if (ConditionKind != other.ConditionKind)
return false;

if (Destination == null)
Expand All @@ -95,7 +99,7 @@ public override int GetHashCode ()
return HashUtils.Combine (
Source.GetHashCode (),
Destination?.GetHashCode () ?? typeof (ControlFlowBranch).GetHashCode (),
IsConditional.GetHashCode ());
ConditionKind.GetHashCode ());
}
}

Expand All @@ -108,9 +112,7 @@ public override int GetHashCode ()
// control flow from try -> finally or from catch -> finally.
IEnumerable<ControlFlowBranch> GetPredecessors (TBlock block);

ControlFlowBranch? GetConditionalSuccessor (TBlock block);

ControlFlowBranch? GetFallThroughSuccessor (TBlock block);
IEnumerable<ControlFlowBranch> GetSuccessors (TBlock block);

bool TryGetEnclosingTryOrCatchOrFilter (TBlock block, [NotNullWhen (true)] out TRegion? tryOrCatchOrFilterRegion);

Expand Down
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