R2RDump - Check disassembler support (#19664)

* Determine if disasm is supported on architectures instead of match

* Readme changes

3 files changed, 15 insertions, 22 deletions

diff --git a/src/tools/r2rdump/R2RDump.cs b/src/tools/r2rdump/R2RDump.cs
index c374050597..e83931c2ad 100644
--- a/src/tools/r2rdump/R2RDump.cs
+++ b/src/tools/r2rdump/R2RDump.cs
@@ -403,16 +403,13 @@ namespace R2RDump
 
                     if (_disasm)
                     {
-                        // TODO: Fix R2RDump issue where an x64 R2R image cannot be dissassembled with the x86 CoreDisTools
-                        // For the short term, we want to error out with a decent message explaining the unexpected error
-                        // Issue #19564: https://github.com/dotnet/coreclr/issues/19564
-                        if (r2r.InputArchitectureMatchesDisassemblerArchitecture())
+                        if (r2r.InputArchitectureSupported() && r2r.DisassemblerArchitectureSupported())
                         {
                             disassembler = new Disassembler(r2r.Image, r2r.Machine);
                         }
                         else
                         {
-                            throw new ArgumentException($"The architecture of input file {filename} is {r2r.Machine.ToString()} and does not match the architecture of the disassembler tools {System.Runtime.InteropServices.RuntimeInformation.ProcessArchitecture.ToString()}");
+                            throw new ArgumentException($"The architecture of input file {filename} ({r2r.Machine.ToString()}) or the architecture of the disassembler tools ({System.Runtime.InteropServices.RuntimeInformation.ProcessArchitecture.ToString()}) is not supported.");
                         }
                     }
 
diff --git a/src/tools/r2rdump/R2RReader.cs b/src/tools/r2rdump/R2RReader.cs
index d6b39a9cbb..2a6c410eaa 100644
--- a/src/tools/r2rdump/R2RReader.cs
+++ b/src/tools/r2rdump/R2RReader.cs
@@ -174,22 +174,18 @@ namespace R2RDump
             }
         }
 
-        public bool InputArchitectureMatchesDisassemblerArchitecture()
+        public bool InputArchitectureSupported()
+        {
+            return Machine != Machine.ArmThumb2; // CoreDisTools often fails to decode when disassembling ARM images (see https://github.com/dotnet/coreclr/issues/19637)
+        }
+
+        // TODO: Fix R2RDump issue where an R2R image cannot be dissassembled with the x86 CoreDisTools
+        // For the short term, we want to error out with a decent message explaining the unexpected error
+        // Issue #19564: https://github.com/dotnet/coreclr/issues/19564
+        public bool DisassemblerArchitectureSupported()
         {
             System.Runtime.InteropServices.Architecture val = System.Runtime.InteropServices.RuntimeInformation.ProcessArchitecture;
-            switch (Machine)
-            {
-                case Machine.Amd64:
-                    return val == System.Runtime.InteropServices.Architecture.X64;
-                case Machine.I386:
-                    return val == System.Runtime.InteropServices.Architecture.X86;
-                case Machine.Arm64:
-                    return val == System.Runtime.InteropServices.Architecture.Arm64;
-                case Machine.ArmThumb2:
-                    return val == System.Runtime.InteropServices.Architecture.Arm;
-                default:
-                    return false;
-            }
+            return val != System.Runtime.InteropServices.Architecture.X86;
         }
 
         /// <summary>
diff --git a/src/tools/r2rdump/README.md b/src/tools/r2rdump/README.md
index 5f022aa5d4..d83b68dfdd 100644
--- a/src/tools/r2rdump/README.md
+++ b/src/tools/r2rdump/README.md
@@ -107,10 +107,10 @@ In x64/Arm/Arm64, GcTransitions are grouped into chunks where each chunk covers
 
 * Support R2RDump on ARM and ARM64 (https://github.com/dotnet/coreclr/issues/19089)
 
-* Fix issue with invalid machine type in COFF header (https://github.com/dotnet/coreclr/issues/19592)
-
 * Parse R2RSections: READYTORUN_SECTION_EXCEPTION_INFO, READYTORUN_SECTION_DEBUG_INFO, READYTORUN_SECTION_DELAYLOAD_METHODCALL_THUNKS, READYTORUN_SECTION_INLINING_INFO, READYTORUN_SECTION_PROFILEDATA_INFO (https://github.com/dotnet/coreclr/issues/19616)
 
 * Reenable R2RDumpTests after making it less fragile
 
-* Fix issue with disasm on Arm (https://github.com/dotnet/coreclr/issues/19637)
+* Fix issues with disasm on Arm (https://github.com/dotnet/coreclr/issues/19637) and disasm using x86 coredistools (https://github.com/dotnet/coreclr/issues/19564)
+
+* Test R2RDump on more test cases to make sure it runs reliably and verify that the output is accurate (list of failing inputs: https://github.com/dotnet/coreclr/issues/19642)