[llvm] [RISCV][Disassembler] Use a table to store all the decoder tables and their associated features. NFC (PR #130883)

[Craig Topper via llvm-commits]

================
@@ -736,27 +754,28 @@ DecodeStatus RISCVDisassembler::getInstruction16(MCInst &MI, uint64_t &Size,
 
   uint32_t Insn = support::endian::read16le(Bytes.data());
 
-  TRY_TO_DECODE_FEATURE_ANY(XqciFeatureGroup, DecoderTableXqci16,
-                            "Qualcomm uC 16bit");
-  TRY_TO_DECODE_FEATURE(
-      RISCV::FeatureVendorXqccmp, DecoderTableXqccmp16,
-      "Xqccmp (Qualcomm 16-bit Push/Pop & Double Move Instructions)");
-  TRY_TO_DECODE_AND_ADD_SP(STI.hasFeature(RISCV::FeatureVendorXwchc),
-                           DecoderTableXwchc16, "WCH QingKe XW");
-
-  // DecoderTableZicfiss16 must be checked before DecoderTable16.
-  TRY_TO_DECODE(true, DecoderTableZicfiss16, "RVZicfiss (Shadow Stack)");
-  TRY_TO_DECODE_AND_ADD_SP(true, DecoderTable16,
-                           "RISCV_C (16-bit Instruction)");
-  TRY_TO_DECODE_AND_ADD_SP(true, DecoderTableRISCV32Only_16,
-                           "RISCV32Only_16 (16-bit Instruction)");
-  // Zc* instructions incompatible with Zcf or Zcd.
-  TRY_TO_DECODE(true, DecoderTableZcOverlap16,
-                "ZcOverlap (16-bit Instructions overlapping with Zcf/Zcd)");
+  for (const DecoderListEntry &Entry : DecoderList16) {
+    if (!Entry.haveRequiredFeatures(STI.getFeatureBits()))
+      continue;
+
+    LLVM_DEBUG(dbgs() << "Trying " << Entry.Desc << "table:\n");
+    DecodeStatus Result =
+        decodeInstruction(Entry.Table, MI, Insn, Address, this, STI);
+    if (Result == MCDisassembler::Fail)
+      continue;
+
+    addSPOperands(MI);
----------------
topperc wrote:

Why introduce additional complexity? Are you were about the time to search MCInstrDesc or do you think its going to do something wrong to some vendor instruction in the future?

https://github.com/llvm/llvm-project/pull/130883