From 12094a8376c9ba0e74497817f4a96f1946091151 Mon Sep 17 00:00:00 2001
From: Daniel Grunwald <daniel@danielgrunwald.de>
Date: Sat, 11 Jul 2020 23:23:06 +0200
Subject: [PATCH] Support extraction out of control-flow IfInstruction even if
 it isn't using a Block as TrueInst/FalseInst.

---
 ICSharpCode.Decompiler/IL/Transforms/FixLoneIsInst.cs | 3 +++
 ICSharpCode.Decompiler/IL/Transforms/ILExtraction.cs  | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/ICSharpCode.Decompiler/IL/Transforms/FixLoneIsInst.cs b/ICSharpCode.Decompiler/IL/Transforms/FixLoneIsInst.cs
index 1f6b9856c..3b270f62b 100644
--- a/ICSharpCode.Decompiler/IL/Transforms/FixLoneIsInst.cs
+++ b/ICSharpCode.Decompiler/IL/Transforms/FixLoneIsInst.cs
@@ -46,6 +46,9 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				if (isInst.Parent.MatchCompEqualsNull(out _) || isInst.Parent.MatchCompNotEqualsNull(out _)) {
 					continue; // supported pattern "expr is T"
 				}
+				if (isInst.Parent is Block { Kind: BlockKind.ControlFlow }) {
+					continue; // supported via StatementBuilder.VisitIsInst
+				}
 				instructionsToFix.Add(isInst);
 			}
 			// Need to delay fixing until we're done with iteration, because Extract() modifies parents
diff --git a/ICSharpCode.Decompiler/IL/Transforms/ILExtraction.cs b/ICSharpCode.Decompiler/IL/Transforms/ILExtraction.cs
index 84878611f..644c43a7f 100644
--- a/ICSharpCode.Decompiler/IL/Transforms/ILExtraction.cs
+++ b/ICSharpCode.Decompiler/IL/Transforms/ILExtraction.cs
@@ -97,6 +97,14 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			ctx.FlagsBeingMoved = instToExtract.Flags;
 			ILInstruction inst = instToExtract;
 			while (inst != null) {
+				if (inst.Parent is IfInstruction ifInst && inst.SlotInfo != IfInstruction.ConditionSlot) {
+					// this context doesn't support extraction, but maybe we can create a block here?
+					if (ifInst.ResultType == StackType.Void) {
+						Block newBlock = new Block();
+						inst.ReplaceWith(newBlock);
+						newBlock.Instructions.Add(inst);
+					}
+				}
 				if (inst.Parent is Block block && block.Kind == BlockKind.ControlFlow) {
 					// We've reached the target block, and extraction is possible all the way.
 					int insertIndex = inst.ChildIndex;