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Untangle CachedDelegateInitialization patterns for Roslyn to avoid false positives

pull/734/merge
Siegfried Pammer 8 years ago
parent
058866ff15
commit
60e4f8dba4
2 changed files with 71 additions and 52 deletions
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  1. 3
      ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs
  2. 120
      ICSharpCode.Decompiler/IL/Transforms/CachedDelegateInitialization.cs

3
ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs
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@ -96,7 +96,8 @@ namespace ICSharpCode.Decompiler.CSharp @@ -96,7 +96,8 @@ namespace ICSharpCode.Decompiler.CSharp
PostOrderTransforms = {
//new UseExitPoints(),
new ConditionDetection(),
// CachedDelegateInitialization must run after ConditionDetection and before/in LoopingBlockTransform.
// CachedDelegateInitialization must run after ConditionDetection and before/in LoopingBlockTransform
// and must run before NullCoalescingTransform
new CachedDelegateInitialization(),
new ILInlining(),
new TransformAssignment(),

120
ICSharpCode.Decompiler/IL/Transforms/CachedDelegateInitialization.cs
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@ -37,24 +37,29 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -37,24 +37,29 @@ namespace ICSharpCode.Decompiler.IL.Transforms
block.Instructions.RemoveAt(i);
continue;
}
if (CachedDelegateInitializationWithLocal(inst, out bool hasFieldStore, out ILVariable v)) {
if (hasFieldStore) {
block.Instructions.RemoveAt(i - 1);
}
if (CachedDelegateInitializationWithLocal(inst)) {
ILInlining.InlineIfPossible(block, ref i, context);
continue;
}
if (CachedDelegateInitializationRoslynWithLocal(inst)) {
block.Instructions.RemoveAt(i);
continue;
}
}
}
}
/// <summary>
/// if (comp(ldsfld CachedAnonMethodDelegate == ldnull)) {
/// stsfld CachedAnonMethodDelegate(DelegateConstruction)
/// }
/// ... one usage of CachedAnonMethodDelegate ...
/// =>
/// ... one usage of DelegateConstruction ...
/// </summary>
bool CachedDelegateInitializationWithField(IfInstruction inst)
{
// if (comp(ldsfld CachedAnonMethodDelegate == ldnull) {
// stsfld CachedAnonMethodDelegate(DelegateConstruction)
// }
// ... one usage of CachedAnonMethodDelegate ...
// =>
// ... one usage of DelegateConstruction ...
Block trueInst = inst.TrueInst as Block;
if (trueInst == null || trueInst.Instructions.Count != 1 || !inst.FalseInst.MatchNop())
return false;
@ -76,56 +81,69 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -76,56 +81,69 @@ namespace ICSharpCode.Decompiler.IL.Transforms
return true;
}
bool CachedDelegateInitializationWithLocal(IfInstruction inst, out bool hasFieldStore, out ILVariable local)
/// <summary>
/// if (comp(ldloc v == ldnull)) {
/// stloc v(DelegateConstruction)
/// }
/// =>
/// stloc v(DelegateConstruction)
/// </summary>
bool CachedDelegateInitializationWithLocal(IfInstruction inst)
{
// [stloc v(ldsfld CachedAnonMethodDelegate)]
// if (comp(ldloc v == ldnull) {
// stloc v(DelegateConstruction)
// [stsfld CachedAnonMethodDelegate(v)]
// }
// =>
// stloc v(DelegateConstruction)
Block trueInst = inst.TrueInst as Block;
hasFieldStore = false;
local = null;
if (trueInst == null || (trueInst.Instructions.Count < 1) || !inst.FalseInst.MatchNop())
if (trueInst == null || (trueInst.Instructions.Count != 1) || !inst.FalseInst.MatchNop())
return false;
if (!inst.Condition.MatchCompEquals(out ILInstruction left, out ILInstruction right) || !left.MatchLdLoc(out ILVariable v) || !right.MatchLdNull())
return false;
ILInstruction value, value2;
var storeInst = trueInst.Instructions.Last();
if (!storeInst.MatchStLoc(v, out value))
return false;
StLoc storeBeforeIf = null;
// the optional field store was moved into storeInst by inline assignment:
if (!(value is NewObj)) {
IField field, field2;
if (value.MatchStsFld(out field, out value2)) {
if (!(value2 is NewObj) || !field.IsCompilerGeneratedOrIsInCompilerGeneratedClass())
return false;
storeBeforeIf = inst.Parent.Children.ElementAtOrDefault(inst.ChildIndex - 1) as StLoc;
if (storeBeforeIf == null || storeBeforeIf.Variable != v || !storeBeforeIf.Value.MatchLdsFld(out field2) || !field.Equals(field2))
return false;
value = value2;
hasFieldStore = true;
} else if (value.MatchStFld(out var target, out field, out value2)) {
// TODO: shouldn't we test 'target'?
if (!(value2 is NewObj) || !field.IsCompilerGeneratedOrIsInCompilerGeneratedClass())
return false;
storeBeforeIf = inst.Parent.Children.ElementAtOrDefault(inst.ChildIndex - 1) as StLoc;
if (storeBeforeIf == null || storeBeforeIf.Variable != v || !storeBeforeIf.Value.MatchLdFld(out var target2, out field2) || !field.Equals(field2))
return false;
value = value2;
hasFieldStore = true;
} else {
return false;
}
}
if (!storeInst.MatchStLoc(v, out ILInstruction value))
return false;
if (!DelegateConstruction.IsDelegateConstruction(value as NewObj, true))
return false;
// do not transform if there are other stores/loads of this variable
if (v.StoreCount != 2 || v.LoadCount != 2 || v.AddressCount != 0)
return false;
// do not transform if there is no usage directly aftewards
var nextInstruction = inst.Parent.Children.ElementAtOrDefault(inst.ChildIndex + 1);
if (nextInstruction == null)
return false;
var usages = nextInstruction.Descendants.Where(i => i.MatchLdLoc(v)).ToArray();
if (usages.Length != 1)
return false;
context.Step("CachedDelegateInitializationWithLocal", inst);
local = v;
inst.ReplaceWith(new StLoc(local, value));
inst.ReplaceWith(new StLoc(v, value));
return true;
}
/// <summary>
/// stloc s(ldobj(ldsflda(CachedAnonMethodDelegate))
/// if (comp(ldloc s == null)) {
/// stloc s(stobj(ldsflda(CachedAnonMethodDelegate), DelegateConstruction))
/// }
/// =>
/// stloc s(DelegateConstruction)
/// </summary>
bool CachedDelegateInitializationRoslynWithLocal(IfInstruction inst)
{
Block trueInst = inst.TrueInst as Block;
if (trueInst == null || (trueInst.Instructions.Count != 1) || !inst.FalseInst.MatchNop())
return false;
if (!inst.Condition.MatchCompEquals(out ILInstruction left, out ILInstruction right) || !left.MatchLdLoc(out ILVariable s) || !right.MatchLdNull())
return false;
var storeInst = trueInst.Instructions.Last() as StLoc;
var storeBeforeIf = inst.Parent.Children.ElementAtOrDefault(inst.ChildIndex - 1) as StLoc;
if (storeBeforeIf == null || storeInst == null || storeBeforeIf.Variable != s || storeInst.Variable != s)
return false;
if (!(storeInst.Value is StObj stobj) || !(storeBeforeIf.Value is LdObj ldobj))
return false;
if (!(stobj.Value is NewObj))
return false;
if (!stobj.Target.MatchLdsFlda(out var field1) || !ldobj.Target.MatchLdsFlda(out var field2) || !field1.Equals(field2))
return false;
if (!DelegateConstruction.IsDelegateConstruction((NewObj)stobj.Value, true))
return false;
context.Step("CachedDelegateInitializationRoslynWithLocal", inst);
storeBeforeIf.Value = stobj.Value;
return true;
}
}

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