From 6c0216bbb9042c55ebee854d32d54afd25090747 Mon Sep 17 00:00:00 2001
From: Daniel Grunwald <daniel@danielgrunwald.de>
Date: Fri, 26 Jul 2019 17:13:47 +0200
Subject: [PATCH] Fix assertion in ReduceNestingTransform: after copying the
 exitInst, it was possible that the old copy of the exitInst became
 unreachable.

---
 .../IL/ControlFlow/ConditionDetection.cs             |  2 +-
 .../IL/Transforms/ReduceNestingTransform.cs          | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/ICSharpCode.Decompiler/IL/ControlFlow/ConditionDetection.cs b/ICSharpCode.Decompiler/IL/ControlFlow/ConditionDetection.cs
index 7025208f1..bb7a120b1 100644
--- a/ICSharpCode.Decompiler/IL/ControlFlow/ConditionDetection.cs
+++ b/ICSharpCode.Decompiler/IL/ControlFlow/ConditionDetection.cs
@@ -354,7 +354,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 			//assert then block terminates
 			var trueExitInst = GetExit(ifInst.TrueInst);
 			var exitInst = GetExit(block);
-			context.Step("Negate if for desired branch "+trueExitInst, ifInst);
+			context.Step($"InvertIf at IL_{ifInst.StartILOffset:x4}", ifInst);
 			
 			//if the then block terminates, else blocks are redundant, and should not exist
 			Debug.Assert(IsEmpty(ifInst.FalseInst));
diff --git a/ICSharpCode.Decompiler/IL/Transforms/ReduceNestingTransform.cs b/ICSharpCode.Decompiler/IL/Transforms/ReduceNestingTransform.cs
index cdd1822a0..e73fab690 100644
--- a/ICSharpCode.Decompiler/IL/Transforms/ReduceNestingTransform.cs
+++ b/ICSharpCode.Decompiler/IL/Transforms/ReduceNestingTransform.cs
@@ -194,6 +194,18 @@ namespace ICSharpCode.Decompiler.IL
 				// if (cond) { ...; exit; }
 				// ...; exit;
 				EnsureEndPointUnreachable(ifInst.TrueInst, exitInst);
+				if (ifInst.FalseInst.HasFlag(InstructionFlags.EndPointUnreachable)) {
+					Debug.Assert(ifInst.HasFlag(InstructionFlags.EndPointUnreachable));
+					Debug.Assert(ifInst.Parent == block);
+					int removeAfter = ifInst.ChildIndex + 1;
+					if (removeAfter < block.Instructions.Count) {
+						// Remove all instructions that ended up dead
+						// (this should just be exitInst itself)
+						Debug.Assert(block.Instructions.SecondToLastOrDefault() == ifInst);
+						Debug.Assert(block.Instructions.Last() == exitInst);
+						block.Instructions.RemoveRange(removeAfter, block.Instructions.Count - removeAfter);
+					}
+				}
 				ExtractElseBlock(ifInst);
 				ifInst = elseIfInst;
 			} while (ifInst != null);