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Improve control flow decompilation (fixes #1133) #1176

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merged 2 commits into from
Jun 13, 2018
Merged

Improve control flow decompilation (fixes #1133) #1176

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3fb7c71
Improve control flow decompilation in ConditionDetection
Chicken-Bones Jun 12, 2018
9937302
Improve control flow decompilation with some compilers
Chicken-Bones Jun 12, 2018
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7 changes: 5 additions & 2 deletions ICSharpCode.Decompiler.Tests/PrettyTestRunner.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -106,7 +106,8 @@ public void ShortCircuit([ValueSource("defaultOptions")] CSharpCompilerOptions c
public void ExceptionHandling([ValueSource("defaultOptions")] CSharpCompilerOptions cscOptions)
{
RunForLibrary(cscOptions: cscOptions, decompilerSettings: new DecompilerSettings {
NullPropagation = false
NullPropagation = false,
RemoveDeadCode = !cscOptions.HasFlag(CSharpCompilerOptions.UseRoslyn)
});
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RemoveDeadCode was introduced for F# (which emits much more dead code than C#).
It's not enabled by default, so it feels weird to have to use it in the C# tests.

As far as I can tell, it's only for while (true) loops compiled with legacy csc in debug mode?
I guess it's fine to special-case this for the test case... but maybe it would be better to have a transform that removes this specific kind of dead store independent of the RemoveDeadCode configuration option.

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A transform would be better, I'll leave that one for you

}

Expand Down Expand Up @@ -161,7 +162,9 @@ public void Generics([ValueSource("defaultOptions")] CSharpCompilerOptions cscOp
[Test]
public void Loops([ValueSource("defaultOptionsWithMcs")] CSharpCompilerOptions cscOptions)
{
RunForLibrary(cscOptions: cscOptions);
RunForLibrary(cscOptions: cscOptions, decompilerSettings: new DecompilerSettings {
RemoveDeadCode = !cscOptions.HasFlag(CSharpCompilerOptions.Optimize)
});
}

[Test]
Expand Down
86 changes: 86 additions & 0 deletions ICSharpCode.Decompiler.Tests/TestCases/Pretty/ExceptionHandling.cs
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Expand Up @@ -195,5 +195,91 @@ public void ThrowInFinally()
throw new Exception();
}
}

#if ROSLYN || !OPT
// TODO Non-Roslyn compilers create a second while loop inside the try, by inverting the if
// This is fixed in the non-optimised version by the enabling the RemoveDeadCode flag
//public bool EarlyExitInLoopTry()
//{
// while (true) {
// try {
// while (B(0)) {
// Console.WriteLine();
// }
//
// return false;
// } catch {
// }
// }
//}
public bool EarlyExitInLoopTry()
{
while (true) {
try {
if (!B(0)) {
return false;
}

Console.WriteLine();
} catch {
}
}
}
#endif

public bool ComplexConditionalReturnInThrow()
{
try {
if (B(0)) {
if (B(1)) {
Console.WriteLine("0 && 1");
return B(2);
}

if (B(3)) {
Console.WriteLine("0 && 3");
return !B(2);
}

Console.WriteLine("0");
}

Console.WriteLine("End Try");

} catch {
try {
try {
if (((B(0) || B(1)) && B(2)) || B(3)) {
return B(4) && !B(5);
}
if (B(6) || B(7)) {
return B(8) || B(9);
}
} catch {
Console.WriteLine("Catch2");
}
return B(10) && B(11);
} catch {
Console.WriteLine("Catch");
} finally {
Console.WriteLine("Finally");
}
}
return false;
}

public void AppropriateLockExit()
{
int num = 0;
lock (this) {
if (num <= 256) {
Console.WriteLine(0);
} else if (num <= 1024) {
Console.WriteLine(1);
} else if (num <= 16384) {
Console.WriteLine(2);
}
}
}
}
}
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