[SystemZ] Support the 'N' code for the odd register in inline-asm.

The odd register of a (128 bit) register pair is accessed with the 'N' code
with an inline assembly operand.

Review: Ulrich Weigand

Differential Revision: https://reviews.llvm.org/D105502

Author: JonPsson

llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp

@@ -764,11 +764,18 @@ void SystemZAsmPrinter::emitMachineConstantPoolValue(
 bool SystemZAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                         const char *ExtraCode,
                                         raw_ostream &OS) {
-  if (ExtraCode)
-    return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS);
+  const MCRegisterInfo &MRI = *TM.getMCRegisterInfo();
+  MachineOperand MO = MI->getOperand(OpNo);
+  if (ExtraCode) {
+    if (ExtraCode[0] == 'N' && !ExtraCode[1] && MO.isReg() &&
+        SystemZ::GR128BitRegClass.contains(MO.getReg()))
+      MO.setReg(MRI.getSubReg(MO.getReg(), SystemZ::subreg_l64));
+    else
+      return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS);
+  }
   SystemZMCInstLower Lower(MF->getContext(), *this);
-  MCOperand MO(Lower.lowerOperand(MI->getOperand(OpNo)));
-  SystemZInstPrinter::printOperand(MO, MAI, OS);
+  MCOperand MCOp(Lower.lowerOperand(MO));
+  SystemZInstPrinter::printOperand(MCOp, MAI, OS);
   return false;
 }
 

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

@@ -1,6 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=s390x-linux-gnu -no-integrated-as < %s | FileCheck %s
 ;
+
 ; Test i128 (tied) operands.
 
 define i32 @fun0(i8* %p1, i32 signext %l1, i8* %p2, i32 signext %l2, i8 zeroext %pad) {
@@ -118,3 +119,19 @@ entry:
   store volatile i128 %IAsm, i128* %Dst
   ret void
 }
+
+; Test access of the odd register using 'N'.
+define i64 @fun5(i64 %b) {
+; CHECK-LABEL: fun5:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lgr %r1, %r2
+; CHECK-NEXT:    lghi %r0, 0
+; CHECK-NEXT:    #APP
+; 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
+}