Improve persistence of IL offsets through various transforms.

ICSharpCode.Decompiler/IL/BlockBuilder.cs

@@ -75,6 +75,7 @@ namespace ICSharpCode.Decompiler.IL
 					var tryBlock = new BlockContainer();
 					tryBlock.ILRange = tryRange;
 					tryCatch = new TryCatch(tryBlock);
+					tryCatch.ILRange = tryRange;
 					tryCatchList.Add(tryCatch);
 					tryInstructionList.Add(tryCatch);
 				}
@@ -90,7 +91,11 @@ namespace ICSharpCode.Decompiler.IL
 					filter = new LdcI4(1);
 				}
 
-				tryCatch.Handlers.Add(new TryCatchHandler(filter, handlerBlock, variableByExceptionHandler[eh]));
+				var handler = new TryCatchHandler(filter, handlerBlock, variableByExceptionHandler[eh]);
+				handler.AddILRange(filter.ILRange);
+				handler.AddILRange(handlerBlock.ILRange);
+				tryCatch.Handlers.Add(handler);
+				tryCatch.AddILRange(handler.ILRange);
 			}
 			if (tryInstructionList.Count > 0) {
 				tryInstructionList = tryInstructionList.OrderBy(tc => tc.TryBlock.ILRange.Start).ThenByDescending(tc => tc.TryBlock.ILRange.End).ToList();
@@ -128,6 +133,7 @@ namespace ICSharpCode.Decompiler.IL
 					// Leave nested containers if necessary
 					while (start >= currentContainer.ILRange.End) {
 						currentContainer = containerStack.Pop();
+						currentBlock = currentContainer.Blocks.Last();
 					}
 					// Enter a handler if necessary
 					BlockContainer handlerContainer;
@@ -136,6 +142,7 @@ namespace ICSharpCode.Decompiler.IL
 						currentContainer = handlerContainer;
 						currentBlock = handlerContainer.EntryPoint;
 					} else {
+						FinalizeCurrentBlock(start, fallthrough: false);
 						// Create the new block
 						currentBlock = new Block();
 						currentContainer.Blocks.Add(currentBlock);
@@ -172,6 +179,7 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			if (currentBlock == null)
 				return;
+			Debug.Assert(currentBlock.ILRange.IsEmpty);
 			currentBlock.ILRange = new Interval(currentBlock.ILRange.Start, currentILOffset);
 			if (fallthrough) {
 				if (currentBlock.Instructions.LastOrDefault() is SwitchInstruction switchInst && switchInst.Sections.Last().Body.MatchNop()) {

ICSharpCode.Decompiler/IL/ControlFlow/AwaitInCatchTransform.cs

@@ -265,6 +265,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				var outer = BlockContainer.FindClosestContainer(container.Parent);
 				if (outer != null) changedContainers.Add(outer);
 				finallyContainer.Blocks.Add(entryPointOfFinally);
+				finallyContainer.ILRange = entryPointOfFinally.ILRange;
 				exitOfFinally.Instructions.RemoveRange(tempStore.ChildIndex, 3);
 				exitOfFinally.Instructions.Add(new Leave(finallyContainer));
 				foreach (var branchToFinally in container.Descendants.OfType<Branch>()) {
@@ -274,8 +275,9 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				foreach (var newBlock in additionalBlocksInFinally) {
 					newBlock.Remove();
 					finallyContainer.Blocks.Add(newBlock);
+					finallyContainer.AddILRange(newBlock.ILRange);
 				}
-				tryCatch.ReplaceWith(new TryFinally(tryCatch.TryBlock, finallyContainer));
+				tryCatch.ReplaceWith(new TryFinally(tryCatch.TryBlock, finallyContainer) {ILRange = tryCatch.TryBlock.ILRange});
 			}
 
 			// clean up all modified containers

ICSharpCode.Decompiler/IL/ControlFlow/ConditionDetection.cs

@@ -425,7 +425,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 		/// </summary>
 		private void OrderIfBlocks(IfInstruction ifInst)
 		{
-			if (IsEmpty(ifInst.FalseInst) || ifInst.TrueInst.ILRange.Start <= ifInst.FalseInst.ILRange.Start)
+			if (IsEmpty(ifInst.FalseInst) || GetILRange(ifInst.TrueInst).Start <= GetILRange(ifInst.FalseInst).Start)
 				return;
 
 			context.Step("Swap then-branch with else-branch to match IL order", ifInst);
@@ -437,6 +437,16 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 			ifInst.Condition = Comp.LogicNot(ifInst.Condition);
 		}
 
+		public static Interval GetILRange(ILInstruction inst)
+		{
+			// some compilers merge the leave instructions for different arguments using stack variables
+			// these get split and inlined, but the ILRange of the value remains a better indicator of the actual location
+			if (inst is Leave leave && !leave.Value.MatchNop())
+				return leave.Value.ILRange;
+
+			return inst.ILRange;
+		}
+
 		/// <summary>
 		/// Compares the current block exit, and the exit of ifInst.ThenInst 
 		/// and inverts if necessary to pick the better exit

ICSharpCode.Decompiler/IL/ControlFlow/ControlFlowSimplification.cs

@@ -132,7 +132,10 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				} else if (targetBlock.Instructions.Count == 1 && targetBlock.Instructions[0] is Leave leave && leave.Value.MatchNop()) {
 					context.Step("Replace branch to leave with leave", branch);
 					// Replace branches to 'leave' instruction with the leave instruction
-					branch.ReplaceWith(leave.Clone());
+					var leave2 = leave.Clone();
+					if (!branch.ILRange.IsEmpty) // use the ILRange of the branch if possible
+						leave2.ILRange = branch.ILRange;
+					branch.ReplaceWith(leave2);
 				}
 				if (targetBlock.IncomingEdgeCount == 0)
 					targetBlock.Instructions.Clear(); // mark the block for deletion
@@ -187,6 +190,10 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				// The C# compiler generates a dead store for the condition of while (true) loops.
 				block.Instructions.RemoveRange(block.Instructions.Count - 3, 2);
 			}
+
+			if (block.ILRange.IsEmpty)
+				block.ILRange = targetBlock.ILRange;
+
 			block.Instructions.Remove(br);
 			block.Instructions.AddRange(targetBlock.Instructions);
 			targetBlock.Instructions.Clear(); // mark targetBlock for deletion

ICSharpCode.Decompiler/IL/ControlFlow/DetectPinnedRegions.cs

@@ -147,7 +147,9 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 					if (p.StackType != StackType.Ref) {
 						arrayToPointer = new Conv(arrayToPointer, p.StackType.ToPrimitiveType(), false, Sign.None);
 					}
-					block.Instructions[block.Instructions.Count - 2] = new StLoc(p, arrayToPointer);
+					block.Instructions[block.Instructions.Count - 2] = new StLoc(p, arrayToPointer) {
+						ILRange = block.Instructions[block.Instructions.Count - 2].ILRange
+					};
 					((Branch)block.Instructions.Last()).TargetBlock = targetBlock;
 					modified = true;
 				}
@@ -343,7 +345,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				}
 			}
 			
-			stLoc.ReplaceWith(new PinnedRegion(stLoc.Variable, stLoc.Value, body));
+			stLoc.ReplaceWith(new PinnedRegion(stLoc.Variable, stLoc.Value, body) { ILRange = stLoc.ILRange });
 			block.Instructions.RemoveAt(block.Instructions.Count - 1); // remove branch into body
 			ProcessPinnedRegion((PinnedRegion)block.Instructions.Last());
 			return true;
@@ -400,6 +402,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 			foreach (var block in body.Blocks)
 				CreatePinnedRegion(block);
 			body.Blocks.RemoveAll(b => b.Instructions.Count == 0); // remove dummy blocks
+			body.ILRange = body.EntryPoint.ILRange;
 		}
 
 		private void MoveArrayToPointerToPinnedRegionInit(PinnedRegion pinnedRegion)

ICSharpCode.Decompiler/IL/ControlFlow/LoopDetection.cs

@@ -646,6 +646,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 			if (exitTargetBlock != null)
 				oldEntryPoint.Instructions.Add(new Branch(exitTargetBlock));
 
+			loopContainer.ILRange = newEntryPoint.ILRange;
 			MoveBlocksIntoContainer(loop, loopContainer);
 
 			// Rewrite branches within the loop from oldEntryPoint to newEntryPoint:
@@ -731,7 +732,8 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 			if (exitTargetBlock != null) {
 				block.Instructions.Add(new Branch(exitTargetBlock));
 			}
-
+			
+			switchContainer.ILRange = newEntryPoint.ILRange;
 			MoveBlocksIntoContainer(nodesInSwitch, switchContainer);
 
 			// Rewrite branches within the loop from oldEntryPoint to newEntryPoint:

ICSharpCode.Decompiler/IL/ControlFlow/SwitchDetection.cs

@@ -180,6 +180,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 					// Remove branch/leave after if; it's getting moved into a section.
 					block.Instructions.RemoveAt(block.Instructions.Count - 1);
 				}
+				sw.ILRange = block.Instructions[block.Instructions.Count - 1].ILRange;
 				block.Instructions[block.Instructions.Count - 1] = sw;
 				
 				// mark all inner blocks that were converted to the switch statement for deletion

ICSharpCode.Decompiler/IL/ControlFlow/YieldReturnDecompiler.cs

@@ -674,6 +674,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 					}
 					// copy over the instruction to the new block
 					newBlock.Instructions.Add(oldInst);
+					newBlock.AddILRange(oldInst.ILRange);
 					UpdateBranchTargets(oldInst);
 				}
 			}
@@ -931,6 +932,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				tryBlock.Instructions.AddRange(block.Instructions);
 				var tryBlockContainer = new BlockContainer();
 				tryBlockContainer.Blocks.Add(tryBlock);
+				tryBlockContainer.ILRange = tryBlock.ILRange;
 				stateToContainer.Add(state, tryBlockContainer);
 
 				ILInstruction finallyBlock;
@@ -944,7 +946,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				}
 
 				block.Instructions.Clear();
-				block.Instructions.Add(new TryFinally(tryBlockContainer, finallyBlock));
+				block.Instructions.Add(new TryFinally(tryBlockContainer, finallyBlock) { ILRange = tryBlockContainer.ILRange});
 			}
 
 			IMethod FindFinallyMethod(int state)

ICSharpCode.Decompiler/IL/Instructions/BlockContainer.cs

@@ -181,6 +181,7 @@ namespace ICSharpCode.Decompiler.IL
 			base.CheckInvariant(phase);
 			Debug.Assert(Blocks.Count > 0 && EntryPoint == Blocks[0]);
 			Debug.Assert(!IsConnected || EntryPoint?.IncomingEdgeCount >= 1);
+			Debug.Assert(EntryPoint == null || Parent is ILFunction || !ILRange.IsEmpty);
 			Debug.Assert(Blocks.All(b => b.HasFlag(InstructionFlags.EndPointUnreachable)));
 			Debug.Assert(Blocks.All(b => b.Kind == BlockKind.ControlFlow)); // this also implies that the blocks don't use FinalInstruction
 			Block bodyStartBlock;

ICSharpCode.Decompiler/IL/Transforms/SwitchOnNullableTransform.cs

@@ -42,6 +42,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				for (int i = block.Instructions.Count - 1; i >= 0; i--) {
 					SwitchInstruction newSwitch;
 					if (MatchSwitchOnNullable(block.Instructions, i, out newSwitch)) {
+						newSwitch.ILRange = block.Instructions[i - 2].ILRange;
 						block.Instructions[i + 1].ReplaceWith(newSwitch);
 						block.Instructions.RemoveRange(i - 2, 3);
 						i -= 2;
@@ -49,6 +50,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 						continue;
 					}
 					if (MatchRoslynSwitchOnNullable(block.Instructions, i, out newSwitch)) {
+						newSwitch.ILRange = block.Instructions[i - 1].ILRange;
 						block.Instructions[i - 1].ReplaceWith(newSwitch);
 						block.Instructions.RemoveRange(i, 2);
 						i--;

ICSharpCode.Decompiler/IL/Transforms/SwitchOnStringTransform.cs

@@ -219,14 +219,17 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			var inst = new SwitchInstruction(stringToInt);
 			inst.Sections.AddRange(sections);
 			if (extraLoad) {
+				inst.ILRange = instructions[i - 2].ILRange;
 				instructions[i - 2].ReplaceWith(inst);
 				instructions.RemoveRange(i - 1, 3);
 				i -= 2;
 			} else {
 				if (keepAssignmentBefore) {
+					inst.ILRange = instructions[i].ILRange;
 					instructions[i].ReplaceWith(inst);
 					instructions.RemoveAt(i + 1);
 				} else {
+					inst.ILRange = instructions[i - 1].ILRange;
 					instructions[i - 1].ReplaceWith(inst);
 					instructions.RemoveRange(i, 2);
 					i--;
@@ -304,7 +307,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			var stringToInt = new StringToInt(switchValue, values.SelectArray(item => item.Item1));
 			var inst = new SwitchInstruction(stringToInt);
 			inst.Sections.AddRange(sections);
-
+			
+			inst.ILRange = instructions[i - 1].ILRange;
 			instructions[i].ReplaceWith(inst);
 			instructions.RemoveAt(i + 1);
 			instructions.RemoveAt(i - 1);
@@ -493,10 +497,12 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			instructions[i + 1].ReplaceWith(inst);
 			if (keepAssignmentBefore) {
 				// delete if (comp(ldloc switchValueVar == ldnull))
+				inst.ILRange = instructions[i].ILRange;
 				instructions.RemoveAt(i);
 				i--;
 			} else {
 				// delete both the if and the assignment before
+				inst.ILRange = instructions[i - 1].ILRange;
 				instructions.RemoveRange(i - 1, 2);
 				i -= 2;
 			}
@@ -711,6 +717,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			var stringToInt = new StringToInt(switchValue, stringValues);
 			var inst = new SwitchInstruction(stringToInt);
 			inst.Sections.AddRange(sections);
+			inst.ILRange = block.Instructions[i].ILRange;
 			block.Instructions[i].ReplaceWith(inst);
 			block.Instructions.RemoveRange(i + 1, 3);
 			info.Transformed = true;
@@ -808,9 +815,11 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			newSwitch.Sections.Add(new SwitchSection { Labels = defaultLabel, Body = defaultSection.Body });
 			instructions[i].ReplaceWith(newSwitch);
 			if (keepAssignmentBefore) {
+				newSwitch.ILRange = instructions[i - 1].ILRange;
 				instructions.RemoveAt(i - 1);
 				i--;
 			} else {
+				newSwitch.ILRange = instructions[i - 2].ILRange;
 				instructions.RemoveRange(i - 2, 2);
 				i -= 2;
 			}

ICSharpCode.Decompiler/IL/Transforms/TransformExpressionTrees.cs

@@ -152,11 +152,13 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			if (!ReadParameters(instruction.Arguments[1], parameterList, parameterVariablesList, new SimpleTypeResolveContext(context.Function.Method)))
 				return (null, SpecialType.UnknownType);
 			var container = new BlockContainer();
+			container.ILRange = instruction.ILRange;
 			var functionType = instruction.Method.ReturnType.TypeArguments[0];
 			var returnType = functionType.GetDelegateInvokeMethod()?.ReturnType;
 			var function = new ILFunction(returnType, parameterList, context.Function.GenericContext, container);
 			function.DelegateType = functionType;
 			function.Variables.AddRange(parameterVariablesList);
+			function.ILRange = instruction.ILRange;
 			lambdaStack.Push(function);
 			var (bodyInstruction, type) = ConvertInstruction(instruction.Arguments[0]);
 			lambdaStack.Pop();