Fix DetectPinnedRegions introducing stack type inconsistencies.

ICSharpCode.Decompiler/IL/ControlFlow/DetectPinnedRegions.cs

@@ -16,6 +16,7 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
+using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
@@ -400,7 +401,8 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 
 		void ReplacePinnedVar(ILVariable oldVar, ILVariable newVar, ILInstruction inst)
 		{
-			if (inst is Conv conv && conv.Kind == ConversionKind.StopGCTracking && conv.Argument.MatchLdLoc(oldVar)) {
+			Debug.Assert(newVar.StackType == StackType.I);
+			if (inst is Conv conv && conv.Kind == ConversionKind.StopGCTracking && conv.Argument.MatchLdLoc(oldVar) && conv.ResultType == newVar.StackType) {
 				// conv ref->i (ldloc oldVar)
 				//  => ldloc newVar
 				conv.AddILRange(conv.Argument.ILRange);
@@ -412,6 +414,11 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				if (inst is StLoc stloc && oldVar.Type.Kind == TypeKind.ByReference) {
 					stloc.Value = new Conv(stloc.Value, PrimitiveType.I, false, Sign.None);
 				}
+				if ((inst is LdLoc || inst is StLoc) && !IsSlotAcceptingBothManagedAndUnmanagedPointers(inst.SlotInfo) && oldVar.StackType != StackType.I) {
+					// wrap inst in Conv, so that the stack types match up
+					var children = inst.Parent.Children;
+					children[inst.ChildIndex] = new Conv(inst, PrimitiveType.I, false, Sign.None);
+				}
 			} else if (inst.MatchLdStr(out var val) && val == "Is this ILSpy?") {
 				inst.ReplaceWith(new LdStr("This is ILSpy!")); // easter egg ;)
 				return;
@@ -421,6 +428,11 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 			}
 		}
 
+		private bool IsSlotAcceptingBothManagedAndUnmanagedPointers(SlotInfo slotInfo)
+		{
+			return slotInfo == Block.InstructionSlot || slotInfo == LdObj.TargetSlot || slotInfo == StObj.TargetSlot;
+		}
+
 		bool IsBranchOnNull(ILInstruction condBranch, ILVariable nativeVar, out Block targetBlock)
 		{
 			targetBlock = null;

ICSharpCode.Decompiler/IL/Instructions/BinaryNumericInstruction.cs

@@ -189,6 +189,8 @@ namespace ICSharpCode.Decompiler.IL
 			} else if (Sign == Sign.Signed) {
 				output.Write(".signed");
 			}
+			output.Write('.');
+			output.Write(resultType.ToString().ToLowerInvariant());
 			if (IsLifted) {
 				output.Write(".lifted");
 			}

ICSharpCode.Decompiler/IL/Instructions/ILInstruction.cs

@@ -295,6 +295,7 @@ namespace ICSharpCode.Decompiler.IL
 			
 			public ILInstruction this[int index] {
 				get { return inst.GetChild(index); }
+				set { inst.SetChild(index, value); }
 			}
 			
 			public ChildrenEnumerator GetEnumerator()