[TableGen] Fix printing second PC-relative operand

If an instruction has several operands and a PC-relative one is not the
first of them, the generator may produce the code that does not pass the
'Address' parameter to the printout method. For example, for an Arm
instruction 'LE LR, $imm', it reuses the same code as for other
instructions where the second operand is not PC-relative:

void ARMInstPrinter::printInstruction(...) {
...
  case 11:
    // BF16VDOTI_VDOTD, BF16VDOTI_VDOTQ, BF16VDOTS_VDOTD, ...
    printOperand(MI, 1, STI, O);
    O << ", ";
    printOperand(MI, 2, STI, O);
    break;
...

The patch fixes that by considering 'PCRel' when comparing
'AsmWriterOperand' values.

Differential Revision: https://reviews.llvm.org/D104698

test/TableGen/AsmWriterPCRelOp.td

@@ -0,0 +1,38 @@
+// RUN: llvm-tblgen -gen-asm-writer -I %p/../../include %s | FileCheck %s
+
+include "llvm/Target/Target.td"
+
+def ArchInstrInfo : InstrInfo { }
+
+def Arch : Target {
+  let InstructionSet = ArchInstrInfo;
+}
+
+def R0 : Register<"r0">;
+def Reg : RegisterClass<"Reg", [i32], 0, (add R0)>;
+
+def IntOperand: Operand<i32>;
+
+def PCRelOperand : Operand<i32> {
+  let OperandType = "OPERAND_PCREL";
+}
+
+def foo : Instruction {
+  let OutOperandList = (outs);
+  let InOperandList = (ins Reg:$reg, IntOperand:$imm);
+  let AsmString = "foo $reg, $imm";
+}
+
+def bar : Instruction {
+  let OutOperandList = (outs);
+  let InOperandList = (ins Reg:$reg, PCRelOperand:$imm);
+  let AsmString = "bar $reg, $imm";
+}
+
+// CHECK:      ArchInstPrinter::printInstruction(
+// CHECK:      // bar, foo
+// CHECK-NEXT: printOperand(MI, 0, O);
+// CHECK:      // foo
+// CHECK-NEXT: printOperand(MI, 1, O);
+// CHECK:      // bar
+// CHECK-NEXT: printOperand(MI, Address, 1, O);

utils/TableGen/AsmWriterInst.h

@@ -66,7 +66,8 @@ namespace llvm {
     bool operator!=(const AsmWriterOperand &Other) const {
       if (OperandType != Other.OperandType || Str != Other.Str) return true;
       if (OperandType == isMachineInstrOperand)
-        return MIOpNo != Other.MIOpNo || MiModifier != Other.MiModifier;
+        return MIOpNo != Other.MIOpNo || MiModifier != Other.MiModifier ||
+               PCRel != Other.PCRel;
       return false;
     }
     bool operator==(const AsmWriterOperand &Other) const {