From acdac3ecf5d82b4bbd20819b5eec3d287ff6d5e5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Srbeck=C3=BD?= <dsrbecky@gmail.com>
Date: Mon, 12 Nov 2007 01:01:29 +0000
Subject: [PATCH] Join consecutive expression together if possible

---
 src/AstMetodBodyBuilder.cs       |  5 +++--
 src/StackExpression.cs           | 17 +++++++++++++++++
 src/StackExpressionCollection.cs | 14 +++++++++++++-
 3 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/src/AstMetodBodyBuilder.cs b/src/AstMetodBodyBuilder.cs
index 7bda9a6e3..37c9609bd 100644
--- a/src/AstMetodBodyBuilder.cs
+++ b/src/AstMetodBodyBuilder.cs
@@ -20,6 +20,7 @@ namespace Decompiler
 			
 			ByteCodeCollection body = new ByteCodeCollection(methodDef);
 			StackExpressionCollection exprCol = new StackExpressionCollection(body);
+			exprCol.Optimize();
 			
 			foreach(VariableDefinition varDef in methodDef.Body.Variables) {
 				Ast.VariableDeclaration astVar = new Ast.VariableDeclaration(varDef.Name);
@@ -73,11 +74,11 @@ namespace Decompiler
 			List<Ast.Expression> allArgs = new List<Ast.Expression>();
 			// Add args from stack
 			allArgs.AddRange(args);
-			// Args generated by nested expressions
+			// Args generated by nested expressions (which must be closed)
 			foreach(StackExpression nestedExpr in expr.LastArguments) {
 				allArgs.Add(new Ast.ParenthesizedExpression((Ast.Expression)MakeCodeDomExpression(methodDef, nestedExpr)));
 			}
-			return MakeCodeDomExpression(methodDef, expr.ExpressionByteCode, args);
+			return MakeCodeDomExpression(methodDef, expr.ExpressionByteCode, allArgs.ToArray());
 		}
 		
 		static object MakeCodeDomExpression(MethodDefinition methodDef, ByteCode byteCode, params Ast.Expression[] args)
diff --git a/src/StackExpression.cs b/src/StackExpression.cs
index 59714bfdf..c2f7d20bc 100644
--- a/src/StackExpression.cs
+++ b/src/StackExpression.cs
@@ -16,6 +16,7 @@ namespace Decompiler
 			get { return expressionByteCode; }
 		}
 		
+		// A list of closed expression for last arguments
 		public List<StackExpression> LastArguments {
 			get { return lastArguments; }
 		}
@@ -32,6 +33,22 @@ namespace Decompiler
 			}
 		}
 		
+		/// <summary>
+		/// Expression is closed if it has no inputs and has exactly one output
+		/// </summary>
+		public bool IsClosed {
+			get {
+				return this.PopCount == 0 &&
+				       this.PushCount == 1;
+			}
+		}
+		
+		public bool IsBranchTarget {
+			get {
+				return this.FirstByteCode.BranchesHere.Count > 0;
+			}
+		}
+		
 		public int PopCount {
 			get {
 				int popCount;
diff --git a/src/StackExpressionCollection.cs b/src/StackExpressionCollection.cs
index 81beb2a81..4c299574e 100644
--- a/src/StackExpressionCollection.cs
+++ b/src/StackExpressionCollection.cs
@@ -18,7 +18,19 @@ namespace Decompiler
 		
 		public void Optimize()
 		{
-			
+			for(int i = 1; i < this.Count; i++) {
+				StackExpression prevExpr = this[i - 1];
+				StackExpression expr = this[i];
+				
+				if (expr.PopCount > 0 && // This expr needs some more arguments
+				    !expr.IsBranchTarget &&
+				    prevExpr.IsClosed)
+				{
+					this.RemoveAt(i - 1); i--;
+					expr.LastArguments.Insert(0, prevExpr);
+					i--;
+				}
+			}
 		}
 	}
 }