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TransformNullPropagationOnUnconstrainedGenericExpression: handle pattern that uses leave instructions instead of stloc into a temporary.

pull/1953/head
Siegfried Pammer 6 years ago
parent
010abebcc9
commit
a7d1d8fad7
2 changed files with 103 additions and 28 deletions
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  1. 21
      ICSharpCode.Decompiler.Tests/TestCases/Pretty/NullPropagation.cs
  2. 110
      ICSharpCode.Decompiler/IL/Transforms/NullPropagationTransform.cs

21
ICSharpCode.Decompiler.Tests/TestCases/Pretty/NullPropagation.cs
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@ -69,6 +69,17 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty @@ -69,6 +69,17 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
}
}
private struct GenericStruct<T1, T2>
{
public T1 Field1;
public T2 Field2;
public override string ToString()
{
return "(" + Field1?.ToString() + ", " + Field2?.ToString() + ")";
}
}
public interface ITest
{
int Int();
@ -243,12 +254,10 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty @@ -243,12 +254,10 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
return t?.Int();
}
// See also: https://github.com/icsharpcode/ILSpy/issues/1050
// The C# compiler generates pretty weird code in this case.
//private static int? GenericRefUnconstrainedInt<T>(ref T t) where T : ITest
//{
// return t?.Int();
//}
private static int? GenericRefUnconstrainedInt<T>(ref T t) where T : ITest
{
return t?.Int();
}
private static int? GenericRefClassConstraintInt<T>(ref T t) where T : class, ITest
{

110
ICSharpCode.Decompiler/IL/Transforms/NullPropagationTransform.cs
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@ -343,16 +343,21 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -343,16 +343,21 @@ namespace ICSharpCode.Decompiler.IL.Transforms
block.Instructions.RemoveRange(pos, 3);
// inline value and wrap it in a NullableUnwrap instruction to produce 'value?'.
target.ReplaceWith(new NullableUnwrap(value.ResultType, value, refInput: true));
var siblings = rewrapPoint.Parent.Children;
int index = rewrapPoint.ChildIndex;
// remove Nullable-ctor, if necessary
if (NullableLiftingTransform.MatchNullableCtor(rewrapPoint, out var utype, out var arg) && arg.InferType(context.TypeSystem).Equals(utype)) {
rewrapPoint = arg;
}
// if the ancestors do not yet have a NullableRewrap instruction
// insert it at the 'rewrapPoint'.
if (needsRewrap) {
var siblings = rewrapPoint.Parent.Children;
int index = rewrapPoint.ChildIndex;
siblings[index] = new NullableRewrap(rewrapPoint);
}
// If the endBlock is only reachable through the current block,
// if the endBlock is only reachable through the current block,
// combine both blocks.
if (endBlock.IncomingEdgeCount == 1) {
if (endBlock?.IncomingEdgeCount == 1) {
block.Instructions.AddRange(endBlock.Instructions);
block.Instructions.RemoveAt(pos + 1);
endBlock.Remove();
@ -374,6 +379,21 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -374,6 +379,21 @@ namespace ICSharpCode.Decompiler.IL.Transforms
// br endBlock
// =>
// stloc resultTemporary(nullable.rewrap(constrained[type].call_instruction(nullable.unwrap(valueExpression), ...)))
//
// -or-
//
// stloc valueTemporary(valueExpression)
// stloc defaultTemporary(default.value type)
// if (logic.not(comp.o(box `0(ldloc defaultTemporary) != ldnull))) Block fallbackBlock {
// stloc defaultTemporary(ldobj type(ldloc valueTemporary))
// stloc valueTemporary(ldloca defaultTemporary)
// if (comp.o(ldloc defaultTemporary == ldnull)) Block fallbackBlock2 {
// leave(ldnull)
// }
// }
// leave (constrained[type].call_instruction(ldloc valueTemporary, ...))
// =>
// leave (nullable.rewrap(constrained[type].call_instruction(nullable.unwrap(valueExpression), ...)))
private bool TransformNullPropagationOnUnconstrainedGenericExpression(Block block, int pos,
out ILInstruction target, out ILInstruction value, out ILInstruction rewrapPoint, out Block endBlock)
{
@ -381,7 +401,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -381,7 +401,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
value = null;
rewrapPoint = null;
endBlock = null;
if (pos + 4 >= block.Instructions.Count)
if (pos + 3 >= block.Instructions.Count)
return false;
// stloc valueTemporary(valueExpression)
if (!(block.Instructions[pos].MatchStLoc(out var valueTemporary, out value)))
@ -399,13 +419,30 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -399,13 +419,30 @@ namespace ICSharpCode.Decompiler.IL.Transforms
// if (logic.not(comp.o(box `0(ldloc defaultTemporary) != ldnull))) Block fallbackBlock
if (!(block.Instructions[pos + 2].MatchIfInstruction(out var condition, out var fallbackBlock1) && condition.MatchCompEqualsNull(out var arg) && arg.MatchLdLoc(defaultTemporary)))
return false;
if (!MatchStLocResultTemporary(block, pos, type, valueTemporary, defaultTemporary, fallbackBlock1, out rewrapPoint, out var call, out endBlock) && !MatchLeaveResult(block, pos, type, valueTemporary, defaultTemporary, fallbackBlock1, out rewrapPoint, out call))
return false;
target = call.Arguments[0];
return true;
}
// stloc resultTemporary(constrained[type].call_instruction(ldloc valueTemporary, ...))
// br IL_0035
private bool MatchStLocResultTemporary(Block block, int pos, IType type, ILVariable valueTemporary, ILVariable defaultTemporary, ILInstruction fallbackBlock1, out ILInstruction rewrapPoint, out CallInstruction call, out Block endBlock)
{
call = null;
endBlock = null;
rewrapPoint = null;
if (pos + 4 >= block.Instructions.Count)
return false;
// stloc resultTemporary(constrained[type].call_instruction(ldloc valueTemporary, ...))
if (!(block.Instructions[pos + 3].MatchStLoc(out var resultTemporary, out rewrapPoint)))
return false;
var loadInCall = FindLoadInExpression(valueTemporary, rewrapPoint);
if (!(loadInCall != null && loadInCall.Ancestors.OfType<CallInstruction>().FirstOrDefault() is CallInstruction call))
if (!(loadInCall != null && loadInCall.Ancestors.OfType<CallInstruction>().FirstOrDefault() is CallInstruction c))
return false;
if (!(call.Arguments.Count > 0 && loadInCall.IsDescendantOf(call.Arguments[0])))
if (!(c.Arguments.Count > 0 && loadInCall.IsDescendantOf(c.Arguments[0])))
return false;
// br IL_0035
if (!(block.Instructions[pos + 4].MatchBranch(out endBlock)))
@ -413,17 +450,40 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -413,17 +450,40 @@ namespace ICSharpCode.Decompiler.IL.Transforms
// Analyze Block fallbackBlock
if (!(fallbackBlock1 is Block b && IsFallbackBlock(b, type, valueTemporary, defaultTemporary, resultTemporary, endBlock)))
return false;
target = call.Arguments[0];
call = c;
return true;
}
ILInstruction FindLoadInExpression(ILVariable variable, ILInstruction expression)
{
foreach (var load in variable.LoadInstructions) {
if (load.IsDescendantOf(expression))
return load;
}
return null;
private bool MatchLeaveResult(Block block, int pos, IType type, ILVariable valueTemporary, ILVariable defaultTemporary, ILInstruction fallbackBlock, out ILInstruction rewrapPoint, out CallInstruction call)
{
call = null;
rewrapPoint = null;
// leave (constrained[type].call_instruction(ldloc valueTemporary, ...))
if (!(block.Instructions[pos + 3] is Leave leave && leave.IsLeavingFunction))
return false;
rewrapPoint = leave.Value;
var loadInCall = FindLoadInExpression(valueTemporary, rewrapPoint);
if (!(loadInCall != null && loadInCall.Ancestors.OfType<CallInstruction>().FirstOrDefault() is CallInstruction c))
return false;
if (!(c.Arguments.Count > 0 && loadInCall.IsDescendantOf(c.Arguments[0])))
return false;
// Analyze Block fallbackBlock
if (!(fallbackBlock is Block b && IsFallbackBlock(b, type, valueTemporary, defaultTemporary, null, leave.TargetContainer)))
return false;
call = c;
return true;
}
private ILInstruction FindLoadInExpression(ILVariable variable, ILInstruction expression)
{
foreach (var load in variable.LoadInstructions) {
if (load.IsDescendantOf(expression))
return load;
}
return null;
}
// Block fallbackBlock {
@ -434,7 +494,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -434,7 +494,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
// br endBlock
// }
// }
private bool IsFallbackBlock(Block block, IType type, ILVariable valueTemporary, ILVariable defaultTemporary, ILVariable resultTemporary, Block endBlock)
private bool IsFallbackBlock(Block block, IType type, ILVariable valueTemporary, ILVariable defaultTemporary, ILVariable resultTemporary, ILInstruction endBlockOrLeaveContainer)
{
if (!(block.Instructions.Count == 3))
return false;
@ -447,18 +507,24 @@ namespace ICSharpCode.Decompiler.IL.Transforms @@ -447,18 +507,24 @@ namespace ICSharpCode.Decompiler.IL.Transforms
if (!(block.Instructions[1].MatchStLoc(valueTemporary, out var defaultAddress) && defaultAddress.MatchLdLoca(defaultTemporary)))
return false;
// if (comp.o(ldloc defaultTemporary == ldnull)) Block fallbackBlock
if (!(block.Instructions[2].MatchIfInstruction(out var condition, out var tmp) && tmp is Block fallbackBlock && condition.MatchCompEqualsNull(out var arg) && arg.MatchLdLoc(defaultTemporary)))
if (!(block.Instructions[2].MatchIfInstruction(out var condition, out var tmp) && condition.MatchCompEqualsNull(out var arg) && arg.MatchLdLoc(defaultTemporary)))
return false;
// Block fallbackBlock {
// stloc resultTemporary(ldnull)
// br endBlock
// }
if (!(fallbackBlock.Instructions.Count == 2))
return false;
if (!(fallbackBlock.Instructions[0].MatchStLoc(resultTemporary, out var defaultValue) && MatchDefaultValueOrLdNull(defaultValue)))
return false;
if (!fallbackBlock.Instructions[1].MatchBranch(endBlock))
var fallbackInst = Block.Unwrap(tmp);
if (fallbackInst is Block fallbackBlock && endBlockOrLeaveContainer is Block endBlock) {
if (!(fallbackBlock.Instructions.Count == 2))
return false;
if (!(fallbackBlock.Instructions[0].MatchStLoc(resultTemporary, out var defaultValue) && MatchDefaultValueOrLdNull(defaultValue)))
return false;
if (!fallbackBlock.Instructions[1].MatchBranch(endBlock))
return false;
} else if (!(fallbackInst is Leave fallbackLeave && endBlockOrLeaveContainer is BlockContainer leaveContainer
&& fallbackLeave.TargetContainer == leaveContainer && MatchDefaultValueOrLdNull(fallbackLeave.Value)))
return false;
return true;
}

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