Fix bug in testcase

Author: rovka

llvm/lib/Target/AMDGPU/SIFrameLowering.cpp

@@ -1027,7 +1027,10 @@ void SIFrameLowering::emitCSRSpillStores(
     // it now. If we have already saved some WWM CSR registers, then the EXEC is
     // already -1 and we don't need to do anything else. Otherwise, set EXEC to
     // -1 here.
-    if (WWMCalleeSavedRegs.empty())
+    if (!ScratchExecCopy)
+      buildScratchExecCopy(LiveUnits, MF, MBB, MBBI, DL, /*IsProlog*/ true,
+                           /*EnableInactiveLanes*/ true);
+    else if (WWMCalleeSavedRegs.empty())
       EnableAllLanes();
     TII->getWholeWaveFunctionSetup(MF)->eraseFromParent();
   } else if (ScratchExecCopy) {

llvm/test/CodeGen/AMDGPU/whole-wave-functions-pei.mir

@@ -360,7 +360,7 @@ body:             |
     ; CHECK-LABEL: name: dont_restore_used_vgprs
     ; CHECK: liveins: $vgpr0, $vgpr20, $vgpr40
     ; CHECK-NEXT: {{  $}}
-    ; CHECK-NEXT: $exec_lo = S_MOV_B32 -1
+    ; CHECK-NEXT: $sgpr0 = S_XOR_SAVEEXEC_B32 -1, implicit-def $exec, implicit-def dead $scc, implicit $exec
     ; CHECK-NEXT: S_NOP 0, implicit $vgpr0, implicit $vgpr20, implicit $vgpr40
     ; CHECK-NEXT: $exec_lo = S_MOV_B32 $sgpr0
     ; CHECK-NEXT: SI_WHOLE_WAVE_FUNC_RETURN killed renamable $sgpr0, implicit killed $vgpr0