[llvm] d5c0561 - AMDGPU: Fix not always reserving VGPRs used for SGPR spilling

[Matt Arsenault via llvm-commits]

Author: Matt Arsenault
Date: 2020-10-22T10:19:19-04:00
New Revision: d5c05616679894b3eb99194f1a3ffeef07c5cb19

URL: https://github.com/llvm/llvm-project/commit/d5c05616679894b3eb99194f1a3ffeef07c5cb19
DIFF: https://github.com/llvm/llvm-project/commit/d5c05616679894b3eb99194f1a3ffeef07c5cb19.diff

LOG: AMDGPU: Fix not always reserving VGPRs used for SGPR spilling

The VGPRs used for SGPR spills need to be reserved, even if we aren't
speculatively reserving one.

This was broken by 117e5609e98b43f925c678b72f816ad3a1c3eee7.

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp b/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
index 708a6dec8fda..83c60b0fb197 100644
--- a/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
@@ -352,6 +352,8 @@ bool SIMachineFunctionInfo::reserveVGPRforSGPRSpills(MachineFunction &MF) {
 
   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;

diff  --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
index 216e00e56a05..a4e94448958f 100644
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -337,9 +337,8 @@ BitVector SIRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   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;
 }