Be less aggressive when removing dead code -- some of it may still be interesting to users.

ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -61,6 +61,9 @@
     <None Include="TestCases\Correctness\StackTypes.il" />
     <None Include="TestCases\Correctness\Uninit.vb" />
     <None Include="TestCases\ILPretty\ConstantBlobs.il" />
+    <None Include="TestCases\ILPretty\CS1xSwitch_Debug.il" />
+    <None Include="TestCases\ILPretty\CS1xSwitch_Release.il" />
+    <None Include="TestCases\ILPretty\Issue1157.il" />
     <None Include="TestCases\ILPretty\Issue684.cs" />
     <None Include="TestCases\ILPretty\Issue684.il" />
     <None Include="TestCases\ILPretty\FSharpLoops.fs" />
@@ -77,6 +80,11 @@
   <ItemGroup>
     <Compile Include="DisassemblerPrettyTestRunner.cs" />
     <Compile Include="TestCases\ILPretty\ConstantBlobs.cs" />
+    <None Include="TestCases\ILPretty\Issue1145.cs" />
+    <Compile Include="TestCases\ILPretty\Issue1157.cs" />
+    <None Include="TestCases\ILPretty\Unsafe.cs" />
+    <None Include="TestCases\ILPretty\CS1xSwitch_Debug.cs" />
+    <None Include="TestCases\ILPretty\CS1xSwitch_Release.cs" />
     <None Include="TestCases\ILPretty\DirectCallToExplicitInterfaceImpl.cs" />
     <Compile Include="TestCases\ILPretty\Issue1389.cs" />
     <Compile Include="TestCases\ILPretty\Issue1454.cs" />

ICSharpCode.Decompiler/IL/ControlFlow/ControlFlowSimplification.cs

@@ -46,7 +46,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				context.CancellationToken.ThrowIfCancellationRequested();
 
 				RemoveNopInstructions(block);
-				RemoveDeadStackStores(block);
+				RemoveDeadStackStores(block, aggressive: context.Settings.RemoveDeadCode);
 
 				InlineVariableInReturnBlock(block, context);
 				// 1st pass SimplifySwitchInstruction before SimplifyBranchChains()
@@ -70,20 +70,33 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 			block.Instructions.RemoveAll(inst => inst.OpCode == OpCode.Nop);
 		}
 
-		private void RemoveDeadStackStores(Block block)
+		private void RemoveDeadStackStores(Block block, bool aggressive)
 		{
 			// Previously copy propagation did this;
 			// ideally the ILReader would already do this,
 			// for now do this here (even though it's not control-flow related).
 			for (int i = block.Instructions.Count - 1; i >= 0; i--) {
 				if (block.Instructions[i] is StLoc stloc && stloc.Variable.IsSingleDefinition && stloc.Variable.LoadCount == 0 && stloc.Variable.Kind == VariableKind.StackSlot) {
-					if (SemanticHelper.IsPure(stloc.Value.Flags)) {
+					if (aggressive ? SemanticHelper.IsPure(stloc.Value.Flags) : IsSimple(stloc.Value)) {
+						Debug.Assert(SemanticHelper.IsPure(stloc.Value.Flags));
 						block.Instructions.RemoveAt(i++);
 					} else {
+						stloc.Value.AddILRange(stloc);
 						stloc.ReplaceWith(stloc.Value);
 					}
 				}
 			}
+
+			bool IsSimple(ILInstruction inst)
+			{
+				switch (inst.OpCode) {
+					case OpCode.LdLoc:
+					case OpCode.LdStr: // C# 1.0 compiler sometimes emits redundant ldstr in switch-on-string pattern
+						return true;
+					default:
+						return false;
+				}
+			}
 		}
 
 		void InlineVariableInReturnBlock(Block block, ILTransformContext context)