[llvm] [LLVM][MC] Add support to cull inactive decoders in decoder emitter (PR #154865)

[Rahul Joshi via llvm-commits]

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@@ -1158,6 +1158,13 @@ class InstrInfo {
   //
   // This option is a temporary migration help. It will go away.
   bit guessInstructionProperties = true;
+
+  // Generate decoders that are specialized per bit width in the generated
+  // decoder/disassembler. This requires use of different `InsnType` for
+  // different bitwidths and defining `InsnBitWidth` template specialization for
+  // the `InsnType` types used. Some common specializations are already defined
+  // in MCDecoder.h.
+  bit SpecializeDecodersPerBitwidth = false;
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jurahul wrote:

If `InstrInfo` is not considered kosher, apart from command line., other option is to add an extra class `DecoderOptions`. 

https://github.com/llvm/llvm-project/pull/154865