[PATCH] D89510: AMDGPU: Fix not always reserving VGPRs used for SGPR spilling

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: saiislam, rampitec.
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The VGPRs used for SGPR spills need to be reserved, even if we aren't
speculatively reserving one.

      

This was broken by 117e5609e98b43f925c678b72f816ad3a1c3eee7 <https://reviews.llvm.org/rG117e5609e98b43f925c678b72f816ad3a1c3eee7>.


https://reviews.llvm.org/D89510

Files:
  llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
  llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp


Index: llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -332,9 +332,8 @@
   for (MCPhysReg Reg : MFI->getVGPRSpillAGPRs())
     reserveRegisterTuples(Reserved, Reg);
 
-  if (MFI->VGPRReservedForSGPRSpill)
-    for (auto SSpill : MFI->getSGPRSpillVGPRs())
-      reserveRegisterTuples(Reserved, SSpill.VGPR);
+  for (auto SSpill : MFI->getSGPRSpillVGPRs())
+    reserveRegisterTuples(Reserved, SSpill.VGPR);
 
   return Reserved;
 }
Index: llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
+++ llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
@@ -352,6 +352,8 @@
 
   Register LaneVGPR = TRI->findUnusedRegister(
       MF.getRegInfo(), &AMDGPU::VGPR_32RegClass, MF, true);
+  if (LaneVGPR == Register())
+    return false;
   SpillVGPRs.push_back(SGPRSpillVGPRCSR(LaneVGPR, None));
   FuncInfo->VGPRReservedForSGPRSpill = LaneVGPR;
   return true;


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