More disassembler improvements (#2078)

* handle "missing" bytes

* Don't require the users to provide `--disasm true` when they already provide custom disassembler settings like --disasmDepth or --disasmFilter

Author: adamsitnik

src/BenchmarkDotNet/ConsoleArguments/CommandLineOptions.cs

@@ -19,6 +19,9 @@ namespace BenchmarkDotNet.ConsoleArguments
     [SuppressMessage("ReSharper", "UnusedAutoPropertyAccessor.Global")]
     public class CommandLineOptions
     {
+        private const int DefaultDisassemblerRecursiveDepth = 1;
+        private bool useDisassemblyDiagnoser;
+
         [Option('j', "job", Required = false, Default = "Default", HelpText = "Dry/Short/Medium/Long or Default")]
         public string BaseJob { get; set; }
 
@@ -35,7 +38,11 @@ public class CommandLineOptions
         public bool UseThreadingDiagnoser { get; set; }
 
         [Option('d', "disasm", Required = false, Default = false, HelpText = "Gets disassembly of benchmarked code")]
-        public bool UseDisassemblyDiagnoser { get; set; }
+        public bool UseDisassemblyDiagnoser
+        {
+            get => useDisassemblyDiagnoser || DisassemblerRecursiveDepth != DefaultDisassemblerRecursiveDepth || DisassemblerFilters.Any();
+            set => useDisassemblyDiagnoser = value;
+        }
 
         [Option('p', "profiler", Required = false, HelpText = "Profiles benchmarked code using selected profiler. Available options: EP/ETW/CV/NativeMemory")]
         public string Profiler { get; set; }
@@ -145,7 +152,7 @@ public class CommandLineOptions
         [Option("list", Required = false, Default = ListBenchmarkCaseMode.Disabled, HelpText = "Prints all of the available benchmark names. Flat/Tree")]
         public ListBenchmarkCaseMode ListBenchmarkCaseMode { get; set; }
 
-        [Option("disasmDepth", Required = false, Default = 1, HelpText = "Sets the recursive depth for the disassembler.")]
+        [Option("disasmDepth", Required = false, Default = DefaultDisassemblerRecursiveDepth, HelpText = "Sets the recursive depth for the disassembler.")]
         public int DisassemblerRecursiveDepth { get; set; }
 
         [Option("disasmFilter", Required = false, HelpText = "Glob patterns applied to full method signatures by the the disassembler.")]

src/BenchmarkDotNet/Disassemblers/ClrMdV2Disassembler.cs

@@ -323,6 +323,11 @@ private static ILToNativeMap[] GetCompleteNativeMap(ClrMethod method, ClrRuntime
                 // Since we care about Tier 1 (if it's present), we "fake" a Tier 1 map.
                 return new[] { new ILToNativeMap() { StartAddress = startAddress, EndAddress = endAddress }};
             }
+            else if (sortedMaps[0].StartAddress != startAddress || (sortedMaps[sortedMaps.Length - 1].EndAddress != endAddress && endAddress != ulong.MaxValue))
+            {
+                // In such situation ILOffsetMap most likely is missing few bytes. We just "extend" it to avoid producing "bad" instructions.
+                return new[] { new ILToNativeMap() { StartAddress = startAddress, EndAddress = endAddress } };
+            }
 
             return sortedMaps;
         }

tests/BenchmarkDotNet.Tests/ConfigParserTests.cs

@@ -474,6 +474,19 @@ public void CanParseDisassemblerWithCustomRecursiveDepth()
             Assert.Equal(depth, diagnoser.Config.MaxDepth);
         }
 
+        [Fact]
+        public void WhenCustomDisassemblerSettingsAreProvidedItsEnabledByDefault()
+        {
+            Verify(new[] { "--disasmDepth", "2" });
+            Verify(new[] { "--disasmFilter", "*" });
+
+            void Verify(string[] args)
+            {
+                var config = ConfigParser.Parse(args, new OutputLogger(Output)).config;
+                Assert.Single(config.GetDiagnosers().OfType<DisassemblyDiagnoser>());
+            }
+        }
+
         [Fact]
         public void CanParseInfo()
         {