[llvm] [AMDGPU] Only try DecoderTables for the current subtarget. NFCI. (PR #82992)

[Jay Foad via llvm-commits]

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@@ -507,27 +510,32 @@ DecodeStatus AMDGPUDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
           tryDecodeInst(DecoderTableGFX90A64, MI, QW, Address, CS))
         break;
 
-      if (tryDecodeInst(DecoderTableGFX864, MI, QW, Address, CS))
+      if ((isVI() || isGFX9()) &&
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jayfoad wrote:

Historical wart: namespace "GFX8" is used for lots of instructions that are shared with GFX9. Perhaps it should be renamed to "GFX8GFX9" or split into a shared part and a GFX8-only part. But I didn't want to touch that in this patch.

https://github.com/llvm/llvm-project/pull/82992