[llvm] [TargetLowering] Add a new function `getNullPtrValue` (PR #126665)

[Matt Arsenault via llvm-commits]

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@@ -6050,3 +6050,12 @@ bool AMDGPUTargetLowering::isReassocProfitable(MachineRegisterInfo &MRI,
                                                Register N0, Register N1) const {
   return MRI.hasOneNonDBGUse(N0); // FIXME: handle regbanks
 }
+
+SDValue AMDGPUTargetLowering::getNullPtrValue(unsigned AS, const SDLoc &DL,
+                                              SelectionDAG &DAG) const {
+  if (AS == AMDGPUAS::PRIVATE_ADDRESS || AS == AMDGPUAS::LOCAL_ADDRESS) {
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arsenm wrote:

I believe we already have one of these in TargetMachine 

https://github.com/llvm/llvm-project/pull/126665