[SystemZ] Bugfix for the 'N' code for inline asm operand.

[jonpa]

Summary

Don't use a local MachineOperand copy in SystemZAsmPrinter::PrintAsmOperand() and change the register as it may break the MRI tracking of register uses. Use an MCOperand instead.

[nathanchance]

Thanks, I can confirm this fixes the crash that I saw and does not regress the build or boot in other ways.

[uweigand]

LGTM, thanks!

llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp

void SystemZAsmPrinter::emitMachineConstantPoolValue(
 
   OutStreamer->emitValue(Expr, Size);
 }
 
 bool SystemZAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                         const char *ExtraCode,
                                         raw_ostream &OS) {
   const MCRegisterInfo &MRI = *TM.getMCRegisterInfo();
-  MachineOperand MO = MI->getOperand(OpNo);
+  const MachineOperand &MO = MI->getOperand(OpNo);
+  MCOperand MCOp;
   if (ExtraCode) {
     if (ExtraCode[0] == 'N' && !ExtraCode[1] && MO.isReg() &&
         SystemZ::GR128BitRegClass.contains(MO.getReg()))
-      MO.setReg(MRI.getSubReg(MO.getReg(), SystemZ::subreg_l64));
+      MCOp =
+          MCOperand::createReg(MRI.getSubReg(MO.getReg(), SystemZ::subreg_l64));
     else
       return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS);
-  }
+  } else {
     SystemZMCInstLower Lower(MF->getContext(), *this);
-  MCOperand MCOp(Lower.lowerOperand(MO));
+    MCOp = Lower.lowerOperand(MO);
+  }
   SystemZInstPrinter::printOperand(MCOp, MAI, OS);
   return false;
 }
 
 bool SystemZAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
                                               unsigned OpNo,
                                               const char *ExtraCode,
                                               raw_ostream &OS) {

llvm/test/CodeGen/SystemZ/inline-asm-i128.ll

 ; CHECK-NEXT:     lgr %r2,%r1
 ; CHECK-NEXT:    #NO_APP
 ; CHECK-NEXT:    br %r14
 entry:
   %Ins = zext i64 %b to i128
   %Res = tail call i64 asm "\09lgr\09$0,${1:N}", "=d,d"(i128 %Ins)
   ret i64 %Res
 }
+
+; Test 'N' with multiple accesses to the same operand and i128 result.
+@V128 = global i128 0, align 16
+define i32 @fun6() {
+; CHECK-LABEL: fun6:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lgrl %r1, V128@GOT
+; CHECK-NEXT:    lg %r3, 8(%r1)
+; CHECK-NEXT:    lg %r2, 0(%r1)
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    ltgr %r3,%r3
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    stg %r2, 0(%r1)
+; CHECK-NEXT:    stg %r3, 8(%r1)
+; CHECK-NEXT:    br %r14
+entry:
+  %0 = load i128, i128* @V128
+  %1 = tail call i128 asm "ltgr ${0:N},${0:N}", "=&d,0"(i128 %0)
+  store i128 %1, i128* @V128
+  ret i32 undef
+}