From f539bee362e1298709d77c83d7cd4939576dad93 Mon Sep 17 00:00:00 2001
From: Chicken-Bones <mehvids@gmail.com>
Date: Wed, 18 Jul 2018 11:07:24 +1000
Subject: [PATCH] Move binary->logical AND to ExpressionTransforms and use
 SemanticHelper.IsPure

---
 .../Transforms/EarlyExpressionTransforms.cs   | 44 -------------------
 .../IL/Transforms/ExpressionTransforms.cs     | 13 ++++++
 2 files changed, 13 insertions(+), 44 deletions(-)

diff --git a/ICSharpCode.Decompiler/IL/Transforms/EarlyExpressionTransforms.cs b/ICSharpCode.Decompiler/IL/Transforms/EarlyExpressionTransforms.cs
index 5c394b9da..bba216c13 100644
--- a/ICSharpCode.Decompiler/IL/Transforms/EarlyExpressionTransforms.cs
+++ b/ICSharpCode.Decompiler/IL/Transforms/EarlyExpressionTransforms.cs
@@ -111,49 +111,5 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			}
 			return null;
 		}
-
-		protected internal override void VisitBinaryNumericInstruction(BinaryNumericInstruction inst)
-		{
-			if (inst.Operator != BinaryNumericOperator.BitAnd)
-				return;
-
-			if (PotentialSideEffects(inst.Left) || PotentialSideEffects(inst.Right))
-				return;
-
-			if (!IsBoolean(inst.Left) || !IsBoolean(inst.Right))
-				return;
-			
-			context.Step("Replace bit.and with logic.and", inst);
-			var expr = IfInstruction.LogicAnd(inst.Left, inst.Right);
-			inst.ReplaceWith(expr);
-			expr.AcceptVisitor(this);
-		}
-
-		private bool IsBoolean(ILInstruction inst) => inst is Comp || inst.InferType().IsKnownType(KnownTypeCode.Boolean);
-
-		private bool PotentialSideEffects(ILInstruction inst)
-		{
-			switch (inst) {
-				case LdLoc _:
-				case LdLoca _:
-				case LdcF4 _:
-				case LdcF8 _:
-				case LdcI4 _:
-				case LdcI8 _:
-				case LdcDecimal _:
-					return false;
-				case Comp c:
-					return PotentialSideEffects(c.Left) || PotentialSideEffects(c.Right);
-				case BinaryNumericInstruction b:
-					return PotentialSideEffects(b.Left) || PotentialSideEffects(b.Right);
-				case BitNot b:
-					return PotentialSideEffects(b.Argument);
-				case Conv c:
-					return PotentialSideEffects(c.Argument);
-
-			}
-
-			return true;
-		}
 	}
 }
diff --git a/ICSharpCode.Decompiler/IL/Transforms/ExpressionTransforms.cs b/ICSharpCode.Decompiler/IL/Transforms/ExpressionTransforms.cs
index 146e22831..515d21a15 100644
--- a/ICSharpCode.Decompiler/IL/Transforms/ExpressionTransforms.cs
+++ b/ICSharpCode.Decompiler/IL/Transforms/ExpressionTransforms.cs
@@ -477,9 +477,22 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 						inst.Right = lhs;
 					}
 					break;
+				case BinaryNumericOperator.BitAnd:
+					if (IsBoolean(inst.Left) && IsBoolean(inst.Right) && SemanticHelper.IsPure(inst.Right.Flags))
+					{
+						context.Step("Replace bit.and with logic.and", inst);
+						var expr = IfInstruction.LogicAnd(inst.Left, inst.Right);
+						inst.ReplaceWith(expr);
+						expr.AcceptVisitor(this);
+					}
+					break;
 			}
 		}
 
+		private static bool IsBoolean(ILInstruction inst) => 
+			inst is Comp c && c.ResultType == StackType.I4 || 
+			inst.InferType().IsKnownType(KnownTypeCode.Boolean);
+
 		protected internal override void VisitTryCatchHandler(TryCatchHandler inst)
 		{
 			base.VisitTryCatchHandler(inst);