[llvm] [RISCV] Add compress patterns for Xqcibi branch instructions (PR #143095)

[Sam Elliott via llvm-commits]

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@@ -341,21 +341,33 @@ def simm12 : RISCVSImmLeafOp<12> {
 def simm12_no6 : ImmLeaf<XLenVT, [{
   return isInt<12>(Imm) && !isInt<6>(Imm) && isInt<12>(-Imm);}]>;
 
-// A 13-bit signed immediate where the least significant bit is zero.
-def bare_simm13_lsb0 : Operand<OtherVT> {
-  let ParserMatchClass = BareSImmNLsb0AsmOperand<13>;
-  let PrintMethod = "printBranchOperand";
-  let EncoderMethod = "getImmOpValueAsrN<1>";
-  let DecoderMethod = "decodeSImmOperandAndLslN<13, 1>";
+class BareSImm13Lsb0MaybeSym : Operand<OtherVT> {
   let MCOperandPredicate = [{
     int64_t Imm;
     if (MCOp.evaluateAsConstantImm(Imm))
       return isShiftedInt<12, 1>(Imm);
     return MCOp.isBareSymbolRef();
   }];
+}
+
+// A 13-bit signed immediate where the least significant bit is zero. The ImmLeaf
+// is needed so that the CompressInstEmitter can correctly add checks for the
+// compress patterns that involve instructions that use this operand. Similar to
+// bare_simm9_lsb0 in RISCVInstrINfoC.td.
+def bare_simm13_lsb0 : BareSImm13Lsb0MaybeSym,
+                       ImmLeaf<XLenVT, [{return isShiftedInt<12, 1>(Imm);}]> {
+  let ParserMatchClass = BareSImmNLsb0AsmOperand<13>;
+  let PrintMethod = "printBranchOperand";
+  let EncoderMethod = "getImmOpValueAsrN<1>";
+  let DecoderMethod = "decodeSImmOperandAndLslN<13, 1>";
   let OperandType = "OPERAND_PCREL";
 }
 
+// We need this (sort of) duplicate defintion since adding ImmLeaf to
+// bare_simm13_lsb0 above makes it not sit well with patterns where it is used to
+// match with a basic block (eg. BccPat<>).
----------------
lenary wrote:

```suggestion
// We need this (sort of) duplicate definition since adding ImmLeaf to
// bare_simm13_lsb0 above makes it not sit well with codegen patterns where it is used to
// match with a basic block (eg. BccPat<>).
```

https://github.com/llvm/llvm-project/pull/143095