Minor refactoring of ILAst pattern matching

ICSharpCode.Decompiler/ILAst/ILAstOptimizer.cs

@@ -236,40 +236,26 @@ namespace ICSharpCode.Decompiler.ILAst
 			} while(modified);
 		}
 		
-		bool IsStloc(ILBasicBlock bb, ref ILVariable locVar, ref ILExpression val, ref ILLabel fallLabel)
-		{
-			if (bb.Body.Count == 1) {
-				ILExpression expr;
-				if (bb.Body[0].Match(ILCode.Stloc, out expr)) {
-					locVar = (ILVariable)expr.Operand;
-					val    = expr.Arguments[0];
-					fallLabel = (ILLabel)bb.FallthoughGoto.Operand;
-					return true;
-				}
-			}
-			return false;
-		}
-		
 		// scope is modified if successful
 		bool TrySimplifyTernaryOperator(List<ILNode> scope, ILBasicBlock head)
 		{
 			Debug.Assert(scope.Contains(head));
 			
-			ILExpression condExpr = null;
-			ILLabel trueLabel = null;
-			ILLabel falseLabel = null;
-			ILVariable trueLocVar = null;
-			ILExpression trueExpr = null;
-			ILLabel trueFall = null;
-			ILVariable falseLocVar = null;
-			ILExpression falseExpr = null;
-			ILLabel falseFall = null;
-			
-			if(head.MatchBrTure(out condExpr, out trueLabel, out falseLabel) &&
+			ILExpression condExpr;
+			ILLabel trueLabel;
+			ILLabel falseLabel;
+			ILVariable trueLocVar;
+			ILExpression trueExpr;
+			ILLabel trueFall;
+			ILVariable falseLocVar;
+			ILExpression falseExpr;
+			ILLabel falseFall;
+			
+			if(head.Match(ILCode.Brtrue, out trueLabel, out condExpr, out falseLabel) &&
 			   labelGlobalRefCount[trueLabel] == 1 &&
 			   labelGlobalRefCount[falseLabel] == 1 &&
-			   IsStloc(labelToBasicBlock[trueLabel], ref trueLocVar, ref trueExpr, ref trueFall) &&
-			   IsStloc(labelToBasicBlock[falseLabel], ref falseLocVar, ref falseExpr, ref falseFall) &&
+			   labelToBasicBlock[trueLabel].Match(ILCode.Stloc, out trueLocVar, out trueExpr, out trueFall) &&
+			   labelToBasicBlock[falseLabel].Match(ILCode.Stloc, out falseLocVar, out falseExpr, out falseFall) &&
 			   trueLocVar == falseLocVar &&
 			   trueFall == falseFall)
 			{
@@ -298,7 +284,7 @@ namespace ICSharpCode.Decompiler.ILAst
 			ILExpression condExpr;
 			ILLabel trueLabel;
 			ILLabel falseLabel;
-			if(head.MatchBrTure(out condExpr, out trueLabel, out falseLabel)) {
+			if(head.Match(ILCode.Brtrue, out trueLabel, out condExpr, out falseLabel)) {
 				for (int pass = 0; pass < 2; pass++) {
 					
 					// On the second pass, swap labels and negate expression of the first branch
@@ -314,7 +300,7 @@ namespace ICSharpCode.Decompiler.ILAst
 					if (scope.Contains(nextBasicBlock) &&
 					    nextBasicBlock != head &&
 					    labelGlobalRefCount[nextBasicBlock.EntryLabel] == 1 &&
-					    nextBasicBlock.MatchBrTure(out nextCondExpr, out nextTrueLablel, out nextFalseLabel) &&
+					    nextBasicBlock.Match(ILCode.Brtrue, out nextTrueLablel, out nextCondExpr, out nextFalseLabel) &&
 					    (otherLablel == nextFalseLabel || otherLablel == nextTrueLablel))
 					{
 						// Create short cicuit branch
@@ -355,9 +341,7 @@ namespace ICSharpCode.Decompiler.ILAst
 			foreach(ILBlock block in method.GetSelfAndChildrenRecursive<ILBlock>()) {
 				for (int i = 0; i < block.Body.Count; i++) {
 					ILLabel targetLabel;
-					if (block.Body[i].Match(ILCode.Br, out targetLabel) ||
-					    block.Body[i].Match(ILCode.Leave, out targetLabel))
-					{
+					if (block.Body[i].Match(ILCode.Br, out targetLabel) || block.Body[i].Match(ILCode.Leave, out targetLabel)) {
 						// Skip extra labels
 						while(nextSibling.ContainsKey(targetLabel) && nextSibling[targetLabel] is ILLabel) {
 							targetLabel = (ILLabel)nextSibling[targetLabel];
@@ -365,17 +349,17 @@ namespace ICSharpCode.Decompiler.ILAst
 						
 						// Inline return statement
 						ILNode target;
-						ILExpression retExpr;
+						List<ILExpression> retArgs;
 						if (nextSibling.TryGetValue(targetLabel, out target) &&
-						    target.Match(ILCode.Ret, out retExpr))
+						    target.Match(ILCode.Ret, out retArgs))
 						{
 							ILVariable locVar;
 							object constValue;
-							if (retExpr.Arguments.Count == 0) {
+							if (retArgs.Count == 0) {
 								block.Body[i] = new ILExpression(ILCode.Ret, null);
-							} else if (retExpr.Arguments.Single().Match(ILCode.Ldloc, out locVar)) {
+							} else if (retArgs.Single().Match(ILCode.Ldloc, out locVar)) {
 								block.Body[i] = new ILExpression(ILCode.Ret, null, new ILExpression(ILCode.Ldloc, locVar));
-							} else if (retExpr.Arguments.Single().Match(ILCode.Ldc_I4, out constValue)) {
+							} else if (retArgs.Single().Match(ILCode.Ldc_I4, out constValue)) {
 								block.Body[i] = new ILExpression(ILCode.Ret, null, new ILExpression(ILCode.Ldc_I4, constValue));
 							}
 						}
@@ -467,7 +451,7 @@ namespace ICSharpCode.Decompiler.ILAst
 					ILExpression condExpr;
 					ILLabel trueLabel;
 					ILLabel falseLabel;
-					if(basicBlock.MatchBrTure(out condExpr, out trueLabel, out falseLabel))
+					if(basicBlock.Match(ILCode.Brtrue, out trueLabel, out condExpr, out falseLabel))
 					{
 						ControlFlowNode trueTarget;
 						labelToCfNode.TryGetValue(trueLabel, out trueTarget);
@@ -581,9 +565,10 @@ namespace ICSharpCode.Decompiler.ILAst
 						
 						// Switch
 						ILLabel[] caseLabels;
-						if (condBranch.Match(ILCode.Switch, out caseLabels)) {
+						List<ILExpression> switchArgs;
+						if (condBranch.Match(ILCode.Switch, out caseLabels, out switchArgs)) {
 							
-							ILSwitch ilSwitch = new ILSwitch() { Condition = condBranch.Arguments.Single() };
+							ILSwitch ilSwitch = new ILSwitch() { Condition = switchArgs.Single() };
 							ILBasicBlock newBB = new ILBasicBlock() {
 								EntryLabel = block.EntryLabel,  // Keep the entry label
 								Body = { ilSwitch },
@@ -662,7 +647,7 @@ namespace ICSharpCode.Decompiler.ILAst
 						ILExpression condExpr;
 						ILLabel trueLabel;
 						ILLabel falseLabel;
-						if(block.MatchBrTure(out condExpr, out trueLabel, out falseLabel)) {
+						if(block.Match(ILCode.Brtrue, out trueLabel, out condExpr, out falseLabel)) {
 							
 							// Swap bodies since that seems to be the usual C# order
 							ILLabel temp = trueLabel;
@@ -852,17 +837,12 @@ namespace ICSharpCode.Decompiler.ILAst
 			return expr != null && expr.Prefixes == null && expr.Code == code;
 		}
 		
-		public static bool Match(this ILNode node, ILCode code, out ILExpression expr)
-		{
-			expr = node as ILExpression;
-			return expr != null && expr.Prefixes == null && expr.Code == code;
-		}
-		
 		public static bool Match<T>(this ILNode node, ILCode code, out T operand)
 		{
 			ILExpression expr = node as ILExpression;
 			if (expr != null && expr.Prefixes == null && expr.Code == code) {
 				operand = (T)expr.Operand;
+				Debug.Assert(expr.Arguments.Count == 0);
 				return true;
 			}
 			operand = default(T);
@@ -873,6 +853,7 @@ namespace ICSharpCode.Decompiler.ILAst
 		{
 			ILExpression expr = node as ILExpression;
 			if (expr != null && expr.Prefixes == null && expr.Code == code) {
+				Debug.Assert(expr.Operand == null);
 				args = expr.Arguments;
 				return true;
 			}
@@ -880,18 +861,41 @@ namespace ICSharpCode.Decompiler.ILAst
 			return false;
 		}
 		
-		public static bool MatchBrTure(this ILBasicBlock bb, out ILExpression condition, out ILLabel trueLabel, out ILLabel falseLabel)
+		public static bool Match<T>(this ILNode node, ILCode code, out T operand, out List<ILExpression> args)
+		{
+			ILExpression expr = node as ILExpression;
+			if (expr != null && expr.Prefixes == null && expr.Code == code) {
+				operand = (T)expr.Operand;
+				args = expr.Arguments;
+				return true;
+			}
+			operand = default(T);
+			args = null;
+			return false;
+		}
+		
+		public static bool Match<T>(this ILNode node, ILCode code, out T operand, out ILExpression arg)
+		{
+			List<ILExpression> args;
+			if (node.Match(code, out operand, out args)) {
+				arg = args.Single();
+				return true;
+			}
+			arg = null;
+			return false;
+		}
+		
+		public static bool Match<T>(this ILBasicBlock bb, ILCode code, out T operand, out ILExpression arg, out ILLabel fallLabel)
 		{
 			if (bb.Body.Count == 1) {
-				if (bb.Body[0].Match(ILCode.Brtrue, out trueLabel)) {
-					condition  = ((ILExpression)bb.Body[0]).Arguments.Single();
-					falseLabel = (ILLabel)((ILExpression)bb.FallthoughGoto).Operand;
+				if (bb.Body[0].Match(code, out operand, out arg)) {
+					fallLabel = (ILLabel)bb.FallthoughGoto.Operand;
 					return true;
 				}
 			}
-			condition  = null;
-			trueLabel  = null;
-			falseLabel = null;
+			operand = default(T);
+			arg = null;
+			fallLabel = null;
 			return false;
 		}