1 files changed, 45 insertions, 3 deletions
diff --git a/llvm/lib/Target/R600/SIMachineFunctionInfo.cpp b/llvm/lib/Target/R600/SIMachineFunctionInfo.cpp
index c53a7e10d54..086f0908703 100644
--- a/llvm/lib/Target/R600/SIMachineFunctionInfo.cpp
+++ b/llvm/lib/Target/R600/SIMachineFunctionInfo.cpp
@@ -12,6 +12,7 @@
 #include "SIMachineFunctionInfo.h"
 #include "SIInstrInfo.h"
 #include "SIRegisterInfo.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/LLVMContext.h"
@@ -90,8 +91,49 @@ void SIMachineFunctionInfo::RegSpillTracker::addSpilledReg(unsigned FrameIndex,
                                                            int Lane) {
   SpilledRegisters[FrameIndex] = SpilledReg(Reg, Lane);
 }
+/// \brief Returns a register that is not used at any point in the function.
+///        If all registers are used, then this function will return
+//         AMDGPU::NoRegister.
+static unsigned findUnusedVGPR(const MachineRegisterInfo &MRI) {
 
-const SIMachineFunctionInfo::SpilledReg&
-SIMachineFunctionInfo::RegSpillTracker::getSpilledReg(unsigned FrameIndex) {
-  return SpilledRegisters[FrameIndex];
+  const TargetRegisterClass *RC = &AMDGPU::VGPR_32RegClass;
+
+  for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
+       I != E; ++I) {
+    if (!MRI.isPhysRegUsed(*I))
+      return *I;
+  }
+  return AMDGPU::NoRegister;
+}
+
+SIMachineFunctionInfo::SpilledReg SIMachineFunctionInfo::getSpilledReg(
+                                                       MachineFunction *MF,
+                                                       unsigned FrameIndex,
+                                                       unsigned SubIdx) {
+  const MachineFrameInfo *FrameInfo = MF->getFrameInfo();
+  MachineRegisterInfo &MRI = MF->getRegInfo();
+  int64_t Offset = FrameInfo->getObjectOffset(FrameIndex);
+  Offset += SubIdx * 4;
+
+  unsigned LaneVGPRIdx = Offset / (64 * 4);
+  unsigned Lane = (Offset / 4) % 64;
+
+  struct SpilledReg Spill;
+
+  if (!LaneVGPRs.count(LaneVGPRIdx)) {
+    unsigned LaneVGPR = findUnusedVGPR(MRI);
+    LaneVGPRs[LaneVGPRIdx] = LaneVGPR;
+    MRI.setPhysRegUsed(LaneVGPR);
+
+    // Add this register as live-in to all blocks to avoid machine verifer
+    // complaining about use of an undefined physical register.
+    for (MachineFunction::iterator BI = MF->begin(), BE = MF->end();
+         BI != BE; ++BI) {
+      BI->addLiveIn(LaneVGPR);
+    }
+  }
+
+  Spill.VGPR = LaneVGPRs[LaneVGPRIdx];
+  Spill.Lane = Lane;
+  return Spill;
 }