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Refactor SwitchOnStringTransform.Run

pull/887/head
Siegfried Pammer 8 years ago
parent
6272c21ece
commit
f988c11229
1 changed files with 52 additions and 55 deletions
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  1. 107
      ICSharpCode.Decompiler/IL/Transforms/SwitchOnStringTransform.cs

107
ICSharpCode.Decompiler/IL/Transforms/SwitchOnStringTransform.cs
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@ -40,52 +40,19 @@ namespace ICSharpCode.Decompiler.IL.Transforms
foreach (var block in function.Descendants.OfType<Block>()) { foreach (var block in function.Descendants.OfType<Block>()) {
bool changed = false; bool changed = false;
for (int i = block.Instructions.Count - 1; i >= 0; i--) { for (int i = block.Instructions.Count - 1; i >= 0; i--) {
SwitchInstruction newSwitch; if (SimplifyCascadingIfStatements(block.Instructions, ref i)) {
if (SimplifyCascadingIfStatements(block.Instructions, i, out newSwitch, out var extraLoad, out var keepAssignmentBefore)) {
if (extraLoad) {
block.Instructions[i - 2].ReplaceWith(newSwitch);
block.Instructions.RemoveRange(i - 1, 3);
i -= 2;
} else {
if (keepAssignmentBefore) {
block.Instructions[i].ReplaceWith(newSwitch);
block.Instructions.RemoveAt(i + 1);
} else {
block.Instructions[i - 1].ReplaceWith(newSwitch);
block.Instructions.RemoveRange(i, 2);
i--;
}
}
changed = true; changed = true;
continue; continue;
} }
if (MatchLegacySwitchOnStringWithHashtable(block.Instructions, i, out newSwitch)) { if (MatchLegacySwitchOnStringWithHashtable(block.Instructions, ref i)) {
block.Instructions[i + 1].ReplaceWith(newSwitch);
block.Instructions.RemoveAt(i);
changed = true; changed = true;
continue; continue;
} }
if (MatchLegacySwitchOnStringWithDict(block.Instructions, i, out newSwitch, out keepAssignmentBefore)) { if (MatchLegacySwitchOnStringWithDict(block.Instructions, ref i)) {
block.Instructions[i + 1].ReplaceWith(newSwitch);
if (keepAssignmentBefore) {
block.Instructions.RemoveAt(i);
i--;
} else {
block.Instructions.RemoveRange(i - 1, 2);
i -= 2;
}
changed = true; changed = true;
continue; continue;
} }
if (MatchRoslynSwitchOnString(block.Instructions, i, out newSwitch, out keepAssignmentBefore)) { if (MatchRoslynSwitchOnString(block.Instructions, ref i)) {
block.Instructions[i].ReplaceWith(newSwitch);
if (keepAssignmentBefore) {
block.Instructions.RemoveAt(i - 1);
i--;
} else {
block.Instructions.RemoveRange(i - 2, 2);
i -= 2;
}
changed = true; changed = true;
continue; continue;
} }
@ -100,11 +67,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
container.SortBlocks(deleteUnreachableBlocks: true); container.SortBlocks(deleteUnreachableBlocks: true);
} }
bool SimplifyCascadingIfStatements(InstructionCollection<ILInstruction> instructions, int i, out SwitchInstruction inst, out bool extraLoad, out bool keepAssignmentBefore) bool SimplifyCascadingIfStatements(InstructionCollection<ILInstruction> instructions, ref int i)
{ {
inst = null;
extraLoad = false;
keepAssignmentBefore = false;
if (i < 1) return false; if (i < 1) return false;
// match first block: checking switch-value for null or first value (Roslyn) // match first block: checking switch-value for null or first value (Roslyn)
// if (call op_Equality(ldloc switchValueVar, ldstr value)) br firstBlock // if (call op_Equality(ldloc switchValueVar, ldstr value)) br firstBlock
@ -116,6 +80,9 @@ namespace ICSharpCode.Decompiler.IL.Transforms
return false; return false;
List<(string, Block)> values = new List<(string, Block)>(); List<(string, Block)> values = new List<(string, Block)>();
ILInstruction switchValue = null; ILInstruction switchValue = null;
bool extraLoad = false;
bool keepAssignmentBefore = false;
// Roslyn: match call to operator ==(string, string) // Roslyn: match call to operator ==(string, string)
if (MatchStringEqualityComparison(condition, out var switchValueVar, out string value)) { if (MatchStringEqualityComparison(condition, out var switchValueVar, out string value)) {
values.Add((value, firstBlock)); values.Add((value, firstBlock));
@ -165,8 +132,22 @@ namespace ICSharpCode.Decompiler.IL.Transforms
var sections = new List<SwitchSection>(values.SelectWithIndex((index, b) => new SwitchSection { Labels = new LongSet(index), Body = new Branch(b.Item2) })); var sections = new List<SwitchSection>(values.SelectWithIndex((index, b) => new SwitchSection { Labels = new LongSet(index), Body = new Branch(b.Item2) }));
sections.Add(new SwitchSection { Labels = new LongSet(new LongInterval(0, sections.Count)).Invert(), Body = new Branch(currentCaseBlock) }); sections.Add(new SwitchSection { Labels = new LongSet(new LongInterval(0, sections.Count)).Invert(), Body = new Branch(currentCaseBlock) });
var stringToInt = new StringToInt(switchValue, values.SelectArray(item => item.Item1)); var stringToInt = new StringToInt(switchValue, values.SelectArray(item => item.Item1));
inst = new SwitchInstruction(stringToInt); var inst = new SwitchInstruction(stringToInt);
inst.Sections.AddRange(sections); inst.Sections.AddRange(sections);
if (extraLoad) {
instructions[i - 2].ReplaceWith(inst);
instructions.RemoveRange(i - 1, 3);
i -= 2;
} else {
if (keepAssignmentBefore) {
instructions[i].ReplaceWith(inst);
instructions.RemoveAt(i + 1);
} else {
instructions[i - 1].ReplaceWith(inst);
instructions.RemoveRange(i, 2);
i--;
}
}
return true; return true;
} }
@ -234,10 +215,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
/// <summary> /// <summary>
/// Matches the C# 2.0 switch-on-string pattern, which uses Dictionary&lt;string, int&gt;. /// Matches the C# 2.0 switch-on-string pattern, which uses Dictionary&lt;string, int&gt;.
/// </summary> /// </summary>
bool MatchLegacySwitchOnStringWithDict(InstructionCollection<ILInstruction> instructions, int i, out SwitchInstruction inst, out bool keepAssignmentBefore) bool MatchLegacySwitchOnStringWithDict(InstructionCollection<ILInstruction> instructions, ref int i)
{ {
inst = null;
keepAssignmentBefore = false;
if (i < 1) return false; if (i < 1) return false;
// match first block: checking switch-value for null // match first block: checking switch-value for null
if (!(instructions[i].MatchIfInstruction(out var condition, out var exitBlockJump) && if (!(instructions[i].MatchIfInstruction(out var condition, out var exitBlockJump) &&
@ -299,13 +278,22 @@ namespace ICSharpCode.Decompiler.IL.Transforms
stringValues.Add(null); stringValues.Add(null);
sections.Add(new SwitchSection() { Labels = label, Body = new Branch(nullValueCaseBlock) }); sections.Add(new SwitchSection() { Labels = label, Body = new Branch(nullValueCaseBlock) });
} }
bool keepAssignmentBefore = false;
if (switchValueVar.LoadCount > 2) { if (switchValueVar.LoadCount > 2) {
switchValue = new LdLoc(switchValueVar); switchValue = new LdLoc(switchValueVar);
keepAssignmentBefore = true; keepAssignmentBefore = true;
} }
var stringToInt = new StringToInt(switchValue, stringValues.ToArray()); var stringToInt = new StringToInt(switchValue, stringValues.ToArray());
inst = new SwitchInstruction(stringToInt); var inst = new SwitchInstruction(stringToInt);
inst.Sections.AddRange(sections); inst.Sections.AddRange(sections);
instructions[i + 1].ReplaceWith(inst);
if (keepAssignmentBefore) {
instructions.RemoveAt(i);
i--;
} else {
instructions.RemoveRange(i - 1, 2);
i -= 2;
}
return true; return true;
} }
@ -365,9 +353,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
return true; return true;
} }
bool MatchLegacySwitchOnStringWithHashtable(InstructionCollection<ILInstruction> instructions, int i, out SwitchInstruction inst) bool MatchLegacySwitchOnStringWithHashtable(InstructionCollection<ILInstruction> instructions, ref int i)
{ {
inst = null;
// match first block: checking compiler-generated Hashtable for null // match first block: checking compiler-generated Hashtable for null
// if (comp(volatile.ldobj System.Collections.Hashtable(ldsflda $$method0x600003f-1) != ldnull)) br switchHeadBlock // if (comp(volatile.ldobj System.Collections.Hashtable(ldsflda $$method0x600003f-1) != ldnull)) br switchHeadBlock
// br tableInitBlock // br tableInitBlock
@ -453,15 +440,15 @@ namespace ICSharpCode.Decompiler.IL.Transforms
sections.Add(new SwitchSection() { Labels = label, Body = new Branch(nullCaseBlock) }); sections.Add(new SwitchSection() { Labels = label, Body = new Branch(nullCaseBlock) });
} }
var stringToInt = new StringToInt(switchValue, stringValues.ToArray()); var stringToInt = new StringToInt(switchValue, stringValues.ToArray());
inst = new SwitchInstruction(stringToInt); var inst = new SwitchInstruction(stringToInt);
inst.Sections.AddRange(sections); inst.Sections.AddRange(sections);
instructions[i + 1].ReplaceWith(inst);
instructions.RemoveAt(i);
return true; return true;
} }
bool MatchRoslynSwitchOnString(InstructionCollection<ILInstruction> instructions, int i, out SwitchInstruction inst, out bool keepAssignmentBefore) bool MatchRoslynSwitchOnString(InstructionCollection<ILInstruction> instructions, ref int i)
{ {
inst = null;
keepAssignmentBefore = false;
if (i < 1) return false; if (i < 1) return false;
if (!(instructions[i] is SwitchInstruction switchInst && switchInst.Value.MatchLdLoc(out var targetVar) && if (!(instructions[i] is SwitchInstruction switchInst && switchInst.Value.MatchLdLoc(out var targetVar) &&
MatchComputeStringHashCall(instructions[i - 1], targetVar, out var switchValue))) MatchComputeStringHashCall(instructions[i - 1], targetVar, out var switchValue)))
@ -499,17 +486,27 @@ namespace ICSharpCode.Decompiler.IL.Transforms
stringValues.Add((index++, stringValue, body)); stringValues.Add((index++, stringValue, body));
} }
ILInstruction switchValueInst = switchValue; ILInstruction switchValueInst = switchValue;
bool keepAssignmentBefore;
if (i > 1 && instructions[i - 2].MatchStLoc(switchValue.Variable, out var switchValueTmp) && if (i > 1 && instructions[i - 2].MatchStLoc(switchValue.Variable, out var switchValueTmp) &&
switchValue.Variable.IsSingleDefinition && switchValue.Variable.LoadCount == switchInst.Sections.Count) { switchValue.Variable.IsSingleDefinition && switchValue.Variable.LoadCount == switchInst.Sections.Count) {
switchValueInst = switchValueTmp; switchValueInst = switchValueTmp;
keepAssignmentBefore = false;
} else { } else {
keepAssignmentBefore = true; keepAssignmentBefore = true;
} }
var defaultLabel = new LongSet(new LongInterval(0, index)).Invert(); var defaultLabel = new LongSet(new LongInterval(0, index)).Invert();
var value = new StringToInt(switchValueInst, stringValues.Select(item => item.Item2).ToArray()); var value = new StringToInt(switchValueInst, stringValues.Select(item => item.Item2).ToArray());
inst = new SwitchInstruction(value); var newSwitch = new SwitchInstruction(value);
inst.Sections.AddRange(stringValues.Select(section => new SwitchSection { Labels = new Util.LongSet(section.Item1), Body = new Branch(section.Item3) })); newSwitch.Sections.AddRange(stringValues.Select(section => new SwitchSection { Labels = new Util.LongSet(section.Item1), Body = new Branch(section.Item3) }));
inst.Sections.Add(new SwitchSection { Labels = defaultLabel, Body = defaultBranch }); newSwitch.Sections.Add(new SwitchSection { Labels = defaultLabel, Body = defaultBranch });
instructions[i].ReplaceWith(newSwitch);
if (keepAssignmentBefore) {
instructions.RemoveAt(i - 1);
i--;
} else {
instructions.RemoveRange(i - 2, 2);
i -= 2;
}
return true; return true;
} }

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