[llvm] [LLVM][MC][DecoderEmitter] Add support to specialize decoder per bitwidth (PR #154865)

[Jessica Clarke via llvm-commits]

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@@ -700,6 +700,12 @@ static constexpr DecoderListEntry DecoderList32[]{
     {DecoderTableZdinxRV32Only32, {}, "RV32-only Zdinx (Double in Integer)"},
 };
 
+// Define bitwidths for various types used to instantiate the decoder.
+template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint16_t> = 16;
+template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint32_t> = 32;
+// Use uint64_t to represent 48 bit instructions.
+template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint64_t> = 48;
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jrtc27 wrote:

Yeah this seems backwards. Shouldn't the decoder know what bit width it's for rather than trying to reinfer it from the type that ended up being used to represent that bit width?

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