AMDGPU: Don't spill SP reg like a normal CSR

llvm-svn: 313217

3 files changed, 16 insertions, 0 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
index 2ecf32c6ffe..ff6fed88e37 100644
--- a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
@@ -594,6 +594,15 @@ void SIFrameLowering::processFunctionBeforeFrameFinalized(
   }
 }
 
+void SIFrameLowering::determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
+                                           RegScavenger *RS) const {
+  TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
+  const SIMachineFunctionInfo *MFI = MF.getInfo<SIMachineFunctionInfo>();
+
+  // The SP is specifically managed and we don't want extra spills of it.
+  SavedRegs.reset(MFI->getStackPtrOffsetReg());
+}
+
 MachineBasicBlock::iterator SIFrameLowering::eliminateCallFramePseudoInstr(
   MachineFunction &MF,
   MachineBasicBlock &MBB,
diff --git a/llvm/lib/Target/AMDGPU/SIFrameLowering.h b/llvm/lib/Target/AMDGPU/SIFrameLowering.h
index c23969d711b..cc1c85ff6bf 100644
--- a/llvm/lib/Target/AMDGPU/SIFrameLowering.h
+++ b/llvm/lib/Target/AMDGPU/SIFrameLowering.h
@@ -35,6 +35,9 @@ public:
   int getFrameIndexReference(const MachineFunction &MF, int FI,
                              unsigned &FrameReg) const override;
 
+  void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
+                            RegScavenger *RS = nullptr) const override;
+
   void processFunctionBeforeFrameFinalized(
     MachineFunction &MF,
     RegScavenger *RS = nullptr) const override;
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
index 2279afaf89e..73eb3a3b5f6 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -818,6 +818,10 @@ void SIInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
   MachineFrameInfo &FrameInfo = MF->getFrameInfo();
   DebugLoc DL = MBB.findDebugLoc(MI);
 
+  assert(SrcReg != MFI->getStackPtrOffsetReg() &&
+         SrcReg != MFI->getFrameOffsetReg() &&
+         SrcReg != MFI->getScratchWaveOffsetReg());
+
   unsigned Size = FrameInfo.getObjectSize(FrameIndex);
   unsigned Align = FrameInfo.getObjectAlignment(FrameIndex);
   MachinePointerInfo PtrInfo