[PowerPC] 32-bit ELF PIC support

This adds initial support for PPC32 ELF PIC (Position Independent Code; the
-fPIC variety), thus rectifying a long-standing deficiency in the PowerPC
backend.

Patch by Justin Hibbits!

llvm-svn: 213427

1 files changed, 13 insertions, 6 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp b/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
index 65e9cf2b43a..3710f92612b 100644
--- a/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -461,7 +461,7 @@ void PPCFrameLowering::replaceFPWithRealFP(MachineFunction &MF) const {
   const PPCRegisterInfo *RegInfo =
     static_cast<const PPCRegisterInfo*>(MF.getTarget().getRegisterInfo());
   bool HasBP = RegInfo->hasBasePointer(MF);
-  unsigned BPReg  = HasBP ? (unsigned) PPC::R30 : FPReg;
+  unsigned BPReg  = HasBP ? (unsigned) RegInfo->getBaseRegister(MF) : FPReg;
   unsigned BP8Reg = HasBP ? (unsigned) PPC::X30 : FPReg;
 
   for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
@@ -506,6 +506,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
   DebugLoc dl;
   bool needsFrameMoves = MMI.hasDebugInfo() ||
     MF.getFunction()->needsUnwindTableEntry();
+  bool isPIC = MF.getTarget().getRelocationModel() == Reloc::PIC_;
 
   // Get processor type.
   bool isPPC64 = Subtarget.isPPC64();
@@ -546,7 +547,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
   bool HasBP = RegInfo->hasBasePointer(MF);
 
   unsigned SPReg       = isPPC64 ? PPC::X1  : PPC::R1;
-  unsigned BPReg       = isPPC64 ? PPC::X30 : PPC::R30;
+  unsigned BPReg       = RegInfo->getBaseRegister(MF);
   unsigned FPReg       = isPPC64 ? PPC::X31 : PPC::R31;
   unsigned LRReg       = isPPC64 ? PPC::LR8 : PPC::LR;
   unsigned ScratchReg  = isPPC64 ? PPC::X0  : PPC::R0;
@@ -602,7 +603,9 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
       BPOffset = FFI->getObjectOffset(BPIndex);
     } else {
       BPOffset =
-        PPCFrameLowering::getBasePointerSaveOffset(isPPC64, isDarwinABI);
+        PPCFrameLowering::getBasePointerSaveOffset(isPPC64,
+                                                   isDarwinABI,
+                                                   isPIC);
     }
   }
 
@@ -839,6 +842,7 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
   // Get the ABI.
   bool isDarwinABI = Subtarget.isDarwinABI();
   bool isSVR4ABI = Subtarget.isSVR4ABI();
+  bool isPIC = MF.getTarget().getRelocationModel() == Reloc::PIC_;
 
   // Check if the link register (LR) has been saved.
   PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
@@ -849,7 +853,7 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
   bool HasBP = RegInfo->hasBasePointer(MF);
 
   unsigned SPReg      = isPPC64 ? PPC::X1  : PPC::R1;
-  unsigned BPReg      = isPPC64 ? PPC::X30 : PPC::R30;
+  unsigned BPReg      = RegInfo->getBaseRegister(MF);
   unsigned FPReg      = isPPC64 ? PPC::X31 : PPC::R31;
   unsigned ScratchReg  = isPPC64 ? PPC::X0  : PPC::R0;
   unsigned TempReg     = isPPC64 ? PPC::X12 : PPC::R12; // another scratch reg
@@ -890,7 +894,9 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
       BPOffset = FFI->getObjectOffset(BPIndex);
     } else {
       BPOffset =
-        PPCFrameLowering::getBasePointerSaveOffset(isPPC64, isDarwinABI);
+        PPCFrameLowering::getBasePointerSaveOffset(isPPC64,
+                                                   isDarwinABI,
+                                                   isPIC);
     }
   }
 
@@ -1067,6 +1073,7 @@ PPCFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
   int FPSI = FI->getFramePointerSaveIndex();
   bool isPPC64 = Subtarget.isPPC64();
   bool isDarwinABI  = Subtarget.isDarwinABI();
+  bool isPIC = MF.getTarget().getRelocationModel() == Reloc::PIC_;
   MachineFrameInfo *MFI = MF.getFrameInfo();
 
   // If the frame pointer save index hasn't been defined yet.
@@ -1081,7 +1088,7 @@ PPCFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
 
   int BPSI = FI->getBasePointerSaveIndex();
   if (!BPSI && RegInfo->hasBasePointer(MF)) {
-    int BPOffset = getBasePointerSaveOffset(isPPC64, isDarwinABI);
+    int BPOffset = getBasePointerSaveOffset(isPPC64, isDarwinABI, isPIC);
     // Allocate the frame index for the base pointer save area.
     BPSI = MFI->CreateFixedObject(isPPC64? 8 : 4, BPOffset, true);
     // Save the result.