[llvm] Add live in for PrivateSegmentSize in GISel path (PR #139968)

[Jake Daly via llvm-commits]

https://github.com/jakemdaly updated https://github.com/llvm/llvm-project/pull/139968

>From 192d2f583dcfb881a450043bcb6b4ebbae3cce62 Mon Sep 17 00:00:00 2001
From: Jake Daly <jake.daly at ymail.com>
Date: Mon, 19 May 2025 15:18:00 -0700
Subject: [PATCH] Add PrivateSegmentSize as livein in GISel path.

---
 llvm/lib/Target/AMDGPU/AMDGPUCallLowering.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUCallLowering.cpp b/llvm/lib/Target/AMDGPU/AMDGPUCallLowering.cpp
index e977b9069173e..98a32f9225ba9 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUCallLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUCallLowering.cpp
@@ -493,6 +493,12 @@ static void allocateHSAUserSGPRs(CCState &CCInfo,
     CCInfo.AllocateReg(FlatScratchInitReg);
   }
 
+  if (UserSGPRInfo.hasPrivateSegmentSize()) {
+    Register PrivateSegmentSizeReg = Info.addPrivateSegmentSize(TRI);
+    MF.addLiveIn(PrivateSegmentSizeReg, &AMDGPU::SGPR_32RegClass);
+    CCInfo.AllocateReg(PrivateSegmentSizeReg);
+  }
+
   // TODO: Add GridWorkGroupCount user SGPRs when used. For now with HSA we read
   // these from the dispatch pointer.
 }