SystemZ: Handle gr128 to fp128 copies in copyPhysReg (#90861)

Author: arsenm

llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp

@@ -856,6 +856,22 @@ void SystemZInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
     return;
   }
 
+  if (SystemZ::FP128BitRegClass.contains(DestReg) &&
+      SystemZ::GR128BitRegClass.contains(SrcReg)) {
+    MCRegister DestRegHi = RI.getSubReg(DestReg, SystemZ::subreg_h64);
+    MCRegister DestRegLo = RI.getSubReg(DestReg, SystemZ::subreg_l64);
+    MCRegister SrcRegHi = RI.getSubReg(SrcReg, SystemZ::subreg_h64);
+    MCRegister SrcRegLo = RI.getSubReg(SrcReg, SystemZ::subreg_l64);
+
+    BuildMI(MBB, MBBI, DL, get(SystemZ::LDGR), DestRegHi)
+        .addReg(SrcRegHi)
+        .addReg(DestReg, RegState::ImplicitDefine);
+
+    BuildMI(MBB, MBBI, DL, get(SystemZ::LDGR), DestRegLo)
+        .addReg(SrcRegLo, getKillRegState(KillSrc));
+    return;
+  }
+
   // Move CC value from a GR32.
   if (DestReg == SystemZ::CC) {
     unsigned Opcode =

llvm/test/CodeGen/SystemZ/copy-phys-reg-gr128-to-fp128.mir

@@ -0,0 +1,49 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 4
+# RUN: llc -mtriple=s390x-ibm-linux -mcpu=z13 -run-pass=postrapseudos -verify-machineinstrs -o - %s | FileCheck %s
+
+---
+name:            copy_gr128_to_fp128__r0q_to_f0q
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $r0q
+    ; CHECK-LABEL: name: copy_gr128_to_fp128__r0q_to_f0q
+    ; CHECK: liveins: $r0q
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $f0d = LDGR $r0d, implicit-def $f0q
+    ; CHECK-NEXT: $f2d = LDGR $r1d
+    ; CHECK-NEXT: Return implicit $f0q
+    $f0q = COPY $r0q
+    Return implicit $f0q
+...
+
+---
+name:            copy_gr128_to_fp128__r0q_to_f0q_killed
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $r0q
+    ; CHECK-LABEL: name: copy_gr128_to_fp128__r0q_to_f0q_killed
+    ; CHECK: liveins: $r0q
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $f0d = LDGR $r0d, implicit-def $f0q
+    ; CHECK-NEXT: $f2d = LDGR killed $r1d
+    ; CHECK-NEXT: Return implicit $f0q
+    $f0q = COPY killed $r0q
+    Return implicit $f0q
+...
+
+---
+name:            copy_gr128_to_fp128__r0q_to_f0q_undef
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $r0q
+    ; CHECK-LABEL: name: copy_gr128_to_fp128__r0q_to_f0q_undef
+    ; CHECK: liveins: $r0q
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $f0q = KILL undef $r0q
+    ; CHECK-NEXT: Return implicit $f0q
+    $f0q = COPY undef $r0q
+    Return implicit $f0q
+...