Don't spill LR as a callee saved register.

llvm-svn: 34533

3 files changed, 19 insertions, 2 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.h b/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.h
index b3e10176d23..e227456e635 100644
--- a/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.h
@@ -26,6 +26,10 @@ private:
   /// stored.  Also used as an anchor for instructions that need to be altered
   /// when using frame pointers (dyna_add, dyna_sub.)
   int FramePointerSaveIndex;
+  
+  /// UsesLR - Indicates whether LR is used in the current function.
+  ///
+  bool UsesLR;
 
 public:
   PPCFunctionInfo(MachineFunction& MF) 
@@ -34,6 +38,9 @@ public:
 
   int getFramePointerSaveIndex() const { return FramePointerSaveIndex; }
   void setFramePointerSaveIndex(int Idx) { FramePointerSaveIndex = Idx; }
+  
+  void setUsesLR(bool U) { UsesLR = U; }
+  bool usesLR()          { return UsesLR; }
 
 };
 
diff --git a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
index 1dda53a342c..86d17f6fa3c 100644
--- a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -439,8 +439,8 @@ bool PPCRegisterInfo::hasFP(const MachineFunction &MF) const {
 /// usesLR - Returns if the link registers (LR) has been used in the function.
 ///
 bool PPCRegisterInfo::usesLR(MachineFunction &MF) const {
-  const bool *PhysRegsUsed = MF.getUsedPhysregs();
-  return PhysRegsUsed[getRARegister()];
+  PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
+  return FI->usesLR();
 }
 
 void PPCRegisterInfo::
@@ -774,6 +774,15 @@ void PPCRegisterInfo::determineFrameLayout(MachineFunction &MF) const {
   MFI->setStackSize(FrameSize);
 }
 
+void PPCRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF)
+  const {
+  //  Save and clear the LR state.
+  PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
+  unsigned LR = getRARegister();
+  FI->setUsesLR(MF.isPhysRegUsed(LR));
+  MF.changePhyRegUsed(LR, false);
+}
+
 void PPCRegisterInfo::emitPrologue(MachineFunction &MF) const {
   MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
   MachineBasicBlock::iterator MBBI = MBB.begin();
diff --git a/llvm/lib/Target/PowerPC/PPCRegisterInfo.h b/llvm/lib/Target/PowerPC/PPCRegisterInfo.h
index eedb62770e8..5ca2d7d2a29 100644
--- a/llvm/lib/Target/PowerPC/PPCRegisterInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCRegisterInfo.h
@@ -82,6 +82,7 @@ public:
   /// frame size.
   void determineFrameLayout(MachineFunction &MF) const;
 
+  void processFunctionBeforeCalleeSavedScan(MachineFunction &MF) const;
   void emitPrologue(MachineFunction &MF) const;
   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const;