Add support for small-model PIC for PowerPC.

[jhibbits]

Summary

Large-model was added first. With the addition of support for multiple PIC
models in LLVM, now add small-model PIC for 32-bit PowerPC, SysV4 ABI. This
generates more optimal code, for shared libraries with less than about 16380
data objects.

[jhibbits]

Note: This also requires the patch in D5332.

[hfinkel]

lib/Target/PowerPC/PPCAsmPrinter.cpp

323

It would be nice to have a comment here explaining what the 4 means.

419

Why?

lib/Target/PowerPC/PPCISelLowering.cpp

1700

Should we rename the GOTPtr variable?

1733

Same here.

lib/Target/PowerPC/PPCInstrInfo.td

3694

Don't need to add a line here.

test/CodeGen/PowerPC/ppc32-pic.ll

11–27

SMALL-BSS-LABEL: foo

(but make the name something that is not a substring of other things)

[jhibbits]

lib/Target/PowerPC/PPCAsmPrinter.cpp

419

This was part of the cleanup of the original check-in (because both implementations are rather intertwined in code touched, I lumped them together). I can remove this change.

lib/Target/PowerPC/PPCISelLowering.cpp

1700

In both cases it points to the GOT. Although, GOTPtr is a little silly for 64-bit.

lib/Target/PowerPC/PPCInstrInfo.td

3694

Hmm, no idea how that snuck in there.

[hfinkel]

lib/Target/PowerPC/PPCAsmPrinter.cpp

419

Specifically, I mean that you renamed ".L.TOC." to ".LTOC.", and I am curious why.

[jhibbits]

lib/Target/PowerPC/PPCAsmPrinter.cpp

419

Aesthetics only. After submitting the PIC and TLS patches, I started cleaning up, and thought the .L.TOC. looked messy. No other reason at all.

[jhibbits]

Address hfinkel's comments

[jhibbits]

Remove files updated in D5332.

[jhibbits]

Update to use the new Module API from D5882 instead.

[jhibbits]

Update the patch to only switch on 'PICLevel::Small', so that the default PIC level is large-model. This way, if no PIC level is specified in the module flags it will always default to Large-model, rather than the current undefined.

[jhibbits]

Update for new "PIC Level" flag

[hfinkel]

LGTM, thanks!

[jhibbits]

Closed by commit rL221791 (authored by @jhibbits).

include/llvm/MC/MCExpr.h

enum VariantKind {
     VK_PPC_GOT_TLSGD_HI,   // symbol@got@tlsgd@h
     VK_PPC_GOT_TLSGD_HA,   // symbol@got@tlsgd@ha
     VK_PPC_TLSGD,          // symbol@tlsgd
     VK_PPC_GOT_TLSLD,      // symbol@got@tlsld
     VK_PPC_GOT_TLSLD_LO,   // symbol@got@tlsld@l
     VK_PPC_GOT_TLSLD_HI,   // symbol@got@tlsld@h
     VK_PPC_GOT_TLSLD_HA,   // symbol@got@tlsld@ha
     VK_PPC_TLSLD,          // symbol@tlsld
+    VK_PPC_LOCAL,          // symbol@local
 
     VK_Mips_GPREL,
     VK_Mips_GOT_CALL,
     VK_Mips_GOT16,
     VK_Mips_GOT,
     VK_Mips_ABS_HI,
     VK_Mips_ABS_LO,
     VK_Mips_TLSGD,

include/llvm/Support/ELF.h

enum {
   R_PPC_REL14_BRTAKEN         = 12,
   R_PPC_REL14_BRNTAKEN        = 13,
   R_PPC_GOT16                 = 14,
   R_PPC_GOT16_LO              = 15,
   R_PPC_GOT16_HI              = 16,
   R_PPC_GOT16_HA              = 17,
   R_PPC_PLTREL24              = 18,
   R_PPC_JMP_SLOT              = 21,
+  R_PPC_LOCAL24PC             = 23,
   R_PPC_REL32                 = 26,
   R_PPC_TLS                   = 67,
   R_PPC_DTPMOD32              = 68,
   R_PPC_TPREL16               = 69,
   R_PPC_TPREL16_LO            = 70,
   R_PPC_TPREL16_HI            = 71,
   R_PPC_TPREL16_HA            = 72,
   R_PPC_TPREL32               = 73,

lib/MC/MCExpr.cpp

StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
   case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h";
   case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha";
   case VK_PPC_TLSGD: return "tlsgd";
   case VK_PPC_GOT_TLSLD: return "got@tlsld";
   case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l";
   case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h";
   case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha";
   case VK_PPC_TLSLD: return "tlsld";
+  case VK_PPC_LOCAL: return "local";
   case VK_Mips_GPREL: return "GPREL";
   case VK_Mips_GOT_CALL: return "GOT_CALL";
   case VK_Mips_GOT16: return "GOT16";
   case VK_Mips_GOT: return "GOT";
   case VK_Mips_ABS_HI: return "ABS_HI";
   case VK_Mips_ABS_LO: return "ABS_LO";
   case VK_Mips_TLSGD: return "TLSGD";
   case VK_Mips_TLSLDM: return "TLSLDM";

lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp

case PPC::fixup_ppc_br24abs:
       switch (Modifier) {
       default: llvm_unreachable("Unsupported Modifier");
       case MCSymbolRefExpr::VK_None:
         Type = ELF::R_PPC_REL24;
         break;
       case MCSymbolRefExpr::VK_PLT:
         Type = ELF::R_PPC_PLTREL24;
         break;
+      case MCSymbolRefExpr::VK_PPC_LOCAL:
+        Type = ELF::R_PPC_LOCAL24PC;
+        break;
       }
       break;
     case PPC::fixup_ppc_brcond14:
     case PPC::fixup_ppc_brcond14abs:
       Type = ELF::R_PPC_REL14;
       break;
     case PPC::fixup_ppc_half16:
       switch (Modifier) {

lib/Target/PowerPC/PPCAsmPrinter.cpp

 
 
 /// EmitInstruction -- Print out a single PowerPC MI in Darwin syntax to
 /// the current output stream.
 ///
 void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
   MCInst TmpInst;
   bool isPPC64 = Subtarget.isPPC64();
+  bool isDarwin = Subtarget.isDarwin();
   
   // Lower multi-instruction pseudo operations.
   switch (MI->getOpcode()) {
   default: break;
   case TargetOpcode::DBG_VALUE:
     llvm_unreachable("Should be handled target independently");
+  case PPC::MoveGOTtoLR: {
+    // Transform %LR = MoveGOTtoLR
+    // Into this: bl _GLOBAL_OFFSET_TABLE_@local-4
+    // _GLOBAL_OFFSET_TABLE_@local-4 (instruction preceding
+    // _GLOBAL_OFFSET_TABLE_) has exactly one instruction:
+    //      blrl
+    // This will return the pointer to _GLOBAL_OFFSET_TABLE_@local
+    MCSymbol *GOTSymbol = OutContext.GetOrCreateSymbol(StringRef("_GLOBAL_OFFSET_TABLE_"));
+    const MCExpr *OffsExpr =
+      MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create(GOTSymbol, MCSymbolRefExpr::VK_PPC_LOCAL,
+                                                      OutContext),
+                              MCConstantExpr::Create(4, OutContext),
+                              OutContext);
+
+    // Emit the 'bl'.
+    EmitToStreamer(OutStreamer, MCInstBuilder(PPC::BL).addExpr(OffsExpr));
+    return;
+  }
   case PPC::MovePCtoLR:
   case PPC::MovePCtoLR8: {
     // Transform %LR = MovePCtoLR
     // Into this, where the label is the PIC base: 
     //     bl L1$pb
     // L1$pb:
     MCSymbol *PICBase = MF->getPICBaseSymbol();
     
     // Emit the 'bl'.
     EmitToStreamer(OutStreamer, MCInstBuilder(PPC::BL)
       // FIXME: We would like an efficient form for this, so we don't have to do
       // a lot of extra uniquing.
       .addExpr(MCSymbolRefExpr::Create(PICBase, OutContext)));
     
     // Emit the label.
     OutStreamer.EmitLabel(PICBase);
     return;
   }
-  case PPC::GetGBRO: {
+  case PPC::UpdateGBR: {
+    // Transform %Rd = UpdateGBR(%Rt, %Ri)
+    // Into: lwz %Rt, .L0$poff - .L0$pb(%Ri)
+    //       add %Rd, %Rt, %Ri
     // Get the offset from the GOT Base Register to the GOT
-    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
-    MCSymbol *PICOffset = MF->getInfo<PPCFunctionInfo>()->getPICOffsetSymbol();
+    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
+    MCSymbol *PICOffset =
+      MF->getInfo<PPCFunctionInfo>()->getPICOffsetSymbol();
     TmpInst.setOpcode(PPC::LWZ);
     const MCExpr *Exp =
       MCSymbolRefExpr::Create(PICOffset, MCSymbolRefExpr::VK_None, OutContext);
     const MCExpr *PB =
       MCSymbolRefExpr::Create(MF->getPICBaseSymbol(),
                               MCSymbolRefExpr::VK_None,
                               OutContext);
-    const MCOperand MO = TmpInst.getOperand(1);
-    TmpInst.getOperand(1) = MCOperand::CreateExpr(MCBinaryExpr::CreateSub(Exp,
-                                                                          PB,
-                                                                          OutContext));
-    TmpInst.addOperand(MO);
+    const MCOperand TR = TmpInst.getOperand(1);
+    const MCOperand PICR = TmpInst.getOperand(0);
+
+    // Step 1: lwz %Rt, .L$poff - .L$pb(%Ri)
+    TmpInst.getOperand(1) =
+        MCOperand::CreateExpr(MCBinaryExpr::CreateSub(Exp,
+    TmpInst.getOperand(0) = TR;
+    TmpInst.getOperand(2) = PICR;
     EmitToStreamer(OutStreamer, TmpInst);
-    return;
-  }
-  case PPC::UpdateGBR: {
+
     // Update the GOT Base Register to point to the GOT.  It may be possible to
     // merge this with the PPC::GetGBRO, doing it all in one step.
-    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
     TmpInst.setOpcode(PPC::ADD4);
-    TmpInst.addOperand(TmpInst.getOperand(0));
+    TmpInst.getOperand(0) = PICR;
+    TmpInst.getOperand(1) = TR;
+    TmpInst.getOperand(2) = PICR;
     EmitToStreamer(OutStreamer, TmpInst);
     return;
   }
   case PPC::LWZtoc: {
-    // Transform %X3 = LWZtoc <ga:@min1>, %X2
-    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
+    // Transform %R3 = LWZtoc <ga:@min1>, %R2
+    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
 
     // Change the opcode to LWZ, and the global address operand to be a
     // reference to the GOT entry we will synthesize later.
     TmpInst.setOpcode(PPC::LWZ);
     const MachineOperand &MO = MI->getOperand(1);
 
     // Map symbol -> label of TOC entry
     assert(MO.isGlobal() || MO.isCPI() || MO.isJTI());
     MCSymbol *MOSymbol = nullptr;
     if (MO.isGlobal())
       MOSymbol = getSymbol(MO.getGlobal());
     else if (MO.isCPI())
       MOSymbol = GetCPISymbol(MO.getIndex());
     else if (MO.isJTI())
       MOSymbol = GetJTISymbol(MO.getIndex());
 
+    if (TM.getPICLevel() == PICLevel::Large) {
       MCSymbol *TOCEntry = lookUpOrCreateTOCEntry(MOSymbol);
 
       const MCExpr *Exp =
         MCSymbolRefExpr::Create(TOCEntry, MCSymbolRefExpr::VK_None,
                                 OutContext);
       const MCExpr *PB =
-      MCSymbolRefExpr::Create(OutContext.GetOrCreateSymbol(Twine(".L.TOC.")),
+        MCSymbolRefExpr::Create(OutContext.GetOrCreateSymbol(Twine(".LTOC.")),
                                                              OutContext);
       Exp = MCBinaryExpr::CreateSub(Exp, PB, OutContext);
       TmpInst.getOperand(1) = MCOperand::CreateExpr(Exp);
+    } else {
+        const MCExpr *Exp =
+          MCSymbolRefExpr::Create(MOSymbol, MCSymbolRefExpr::VK_GOT,
+                                  OutContext);
+        TmpInst.getOperand(1) = MCOperand::CreateExpr(Exp);
+    }
     EmitToStreamer(OutStreamer, TmpInst);
     return;
   }
   case PPC::LDtocJTI:
   case PPC::LDtocCPT:
   case PPC::LDtoc: {
     // Transform %X3 = LDtoc <ga:@min1>, %X2
-    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
+    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
 
     // Change the opcode to LD, and the global address operand to be a
     // reference to the TOC entry we will synthesize later.
     TmpInst.setOpcode(PPC::LD);
     const MachineOperand &MO = MI->getOperand(1);
 
     // Map symbol -> label of TOC entry
     assert(MO.isGlobal() || MO.isCPI() || MO.isJTI());
const MCExpr *Exp =
                               OutContext);
     TmpInst.getOperand(1) = MCOperand::CreateExpr(Exp);
     EmitToStreamer(OutStreamer, TmpInst);
     return;
   }
       
   case PPC::ADDIStocHA: {
     // Transform %Xd = ADDIStocHA %X2, <ga:@sym>
-    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
+    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
 
     // Change the opcode to ADDIS8.  If the global address is external, has
     // common linkage, is a non-local function address, or is a jump table
     // address, then generate a TOC entry and reference that.  Otherwise
     // reference the symbol directly.
     TmpInst.setOpcode(PPC::ADDIS8);
     const MachineOperand &MO = MI->getOperand(2);
     assert((MO.isGlobal() || MO.isCPI() || MO.isJTI()) &&
const MCExpr *Exp =
       MCSymbolRefExpr::Create(MOSymbol, MCSymbolRefExpr::VK_PPC_TOC_HA,
                               OutContext);
     TmpInst.getOperand(2) = MCOperand::CreateExpr(Exp);
     EmitToStreamer(OutStreamer, TmpInst);
     return;
   }
   case PPC::LDtocL: {
     // Transform %Xd = LDtocL <ga:@sym>, %Xs
-    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
+    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
 
     // Change the opcode to LD.  If the global address is external, has
     // common linkage, or is a jump table address, then reference the
     // associated TOC entry.  Otherwise reference the symbol directly.
     TmpInst.setOpcode(PPC::LD);
     const MachineOperand &MO = MI->getOperand(1);
     assert((MO.isGlobal() || MO.isJTI() || MO.isCPI()) &&
            "Invalid operand for LDtocL!");
const MCExpr *Exp =
       MCSymbolRefExpr::Create(MOSymbol, MCSymbolRefExpr::VK_PPC_TOC_LO,
                               OutContext);
     TmpInst.getOperand(1) = MCOperand::CreateExpr(Exp);
     EmitToStreamer(OutStreamer, TmpInst);
     return;
   }
   case PPC::ADDItocL: {
     // Transform %Xd = ADDItocL %Xs, <ga:@sym>
-    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
+    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
 
     // Change the opcode to ADDI8.  If the global address is external, then
     // generate a TOC entry and reference that.  Otherwise reference the
     // symbol directly.
     TmpInst.setOpcode(PPC::ADDI8);
     const MachineOperand &MO = MI->getOperand(2);
     assert((MO.isGlobal() || MO.isCPI()) && "Invalid operand for ADDItocL");
     MCSymbol *MOSymbol = nullptr;
EmitToStreamer(OutStreamer, MCInstBuilder(PPC::ADDIS8)
                                 .addReg(MI->getOperand(0).getReg())
                                 .addReg(PPC::X2)
                                 .addExpr(SymGotTprel));
     return;
   }
   case PPC::LDgotTprelL:
   case PPC::LDgotTprelL32: {
     // Transform %Xd = LDgotTprelL <ga:@sym>, %Xs
-    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
+    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
 
     // Change the opcode to LD.
     TmpInst.setOpcode(isPPC64 ? PPC::LD : PPC::LWZ);
     const MachineOperand &MO = MI->getOperand(1);
     const GlobalValue *GValue = MO.getGlobal();
     MCSymbol *MOSymbol = getSymbol(GValue);
     const MCExpr *Exp =
       MCSymbolRefExpr::Create(MOSymbol, MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO,
if (!Subtarget.isDarwin()) {
       if (MO.isGlobal() && MO.getGlobal()->getAlignment() < 4)
         llvm_unreachable("Global must be word-aligned for LD, STD, LWA!");
     }
     // Now process the instruction normally.
     break;
   }
   }
 
-  LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, Subtarget.isDarwin());
+  LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
   EmitToStreamer(OutStreamer, TmpInst);
 }
 
 void PPCLinuxAsmPrinter::EmitStartOfAsmFile(Module &M) {
   if (Subtarget.isELFv2ABI()) {
     PPCTargetStreamer *TS =
       static_cast<PPCTargetStreamer *>(OutStreamer.getTargetStreamer());
 
     if (TS)
       TS->emitAbiVersion(2);
   }
 
   if (Subtarget.isPPC64() || TM.getRelocationModel() != Reloc::PIC_)
     return AsmPrinter::EmitStartOfAsmFile(M);
 
-  // FIXME: The use of .got2 assumes large GOT model (-fPIC), which is not
-  // optimal for some cases.  We should consider supporting small model (-fpic)
-  // as well in the future.
-  assert(TM.getCodeModel() != CodeModel::Small &&
-         "Small code model PIC is currently unsupported.");
+  if (TM.getPICLevel() != PICLevel::Large)
+    return AsmPrinter::EmitStartOfAsmFile(M);
+
   OutStreamer.SwitchSection(OutContext.getELFSection(".got2",
          ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC,
          SectionKind::getReadOnly()));
 
-  MCSymbol *TOCSym = OutContext.GetOrCreateSymbol(Twine(".L.TOC."));
+  MCSymbol *TOCSym = OutContext.GetOrCreateSymbol(Twine(".LTOC."));
   MCSymbol *CurrentPos = OutContext.CreateTempSymbol();
 
   OutStreamer.EmitLabel(CurrentPos);
 
   // The GOT pointer points to the middle of the GOT, in order to reference the
   // entire 64kB range.  0x8000 is the midpoint.
   const MCExpr *tocExpr =
     MCBinaryExpr::CreateAdd(MCSymbolRefExpr::Create(CurrentPos, OutContext),
                             MCConstantExpr::Create(0x8000, OutContext),
                             OutContext);
 
   OutStreamer.EmitAssignment(TOCSym, tocExpr);
 
   OutStreamer.SwitchSection(getObjFileLowering().getTextSection());
 }
 
 void PPCLinuxAsmPrinter::EmitFunctionEntryLabel() {
   // linux/ppc32 - Normal entry label.
-  if (!Subtarget.isPPC64() && TM.getRelocationModel() != Reloc::PIC_)
+  if (!Subtarget.isPPC64() && 
+      (TM.getRelocationModel() != Reloc::PIC_ || 
+       TM.getPICLevel() != PICLevel::Large))
     return AsmPrinter::EmitFunctionEntryLabel();
 
-  if (!Subtarget.isPPC64()) {
+  if (!Subtarget.isPPC64() && TM.getRelocationModel() == Reloc::PIC_
+      && TM.getPICLevel() == PICLevel::Large) {
     const PPCFunctionInfo *PPCFI = MF->getInfo<PPCFunctionInfo>();
     if (PPCFI->usesPICBase()) {
       MCSymbol *RelocSymbol = PPCFI->getPICOffsetSymbol();
       MCSymbol *PICBase = MF->getPICBaseSymbol();
       OutStreamer.EmitLabel(RelocSymbol);
 
       const MCExpr *OffsExpr =
         MCBinaryExpr::CreateSub(
-          MCSymbolRefExpr::Create(OutContext.GetOrCreateSymbol(Twine(".L.TOC.")),
+          MCSymbolRefExpr::Create(OutContext.GetOrCreateSymbol(Twine(".LTOC.")),
                                                                OutContext),
                                   MCSymbolRefExpr::Create(PICBase, OutContext),
           OutContext);
       OutStreamer.EmitValue(OffsExpr, 4);
       OutStreamer.EmitLabel(CurrentFnSym);
       return;
     } else
       return AsmPrinter::EmitFunctionEntryLabel();

lib/Target/PowerPC/PPCISelDAGToDAG.cpp

if (!GlobalBaseReg) {
     DebugLoc dl;
 
     if (PPCLowering->getPointerTy() == MVT::i32) {
       if (PPCSubTarget->isTargetELF())
         GlobalBaseReg = PPC::R30;
       else
         GlobalBaseReg =
           RegInfo->createVirtualRegister(&PPC::GPRC_NOR0RegClass);
+      if (PPCSubTarget->isTargetELF() &&
+             TM.getPICLevel() == PICLevel::Small)
+        BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MoveGOTtoLR));
+      else
         BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MovePCtoLR));
       BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MFLR), GlobalBaseReg);
-      if (PPCSubTarget->isTargetELF()) {
+      if (PPCSubTarget->isTargetELF() && TM.getPICLevel() == PICLevel::Large) {
         unsigned TempReg = RegInfo->createVirtualRegister(&PPC::GPRCRegClass);
         BuildMI(FirstMBB, MBBI, dl,
-                TII.get(PPC::GetGBRO), TempReg).addReg(GlobalBaseReg);
-        BuildMI(FirstMBB, MBBI, dl,
-                TII.get(PPC::UpdateGBR)).addReg(GlobalBaseReg).addReg(TempReg);
+                TII.get(PPC::UpdateGBR)).addReg(GlobalBaseReg)
+                .addReg(TempReg, RegState::Define).addReg(GlobalBaseReg);
         MF->getInfo<PPCFunctionInfo>()->setUsesPICBase(true);
       }
     } else {
       GlobalBaseReg = RegInfo->createVirtualRegister(&PPC::G8RC_NOX0RegClass);
       BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MovePCtoLR8));
       BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MFLR8), GlobalBaseReg);
     }
   }
case ISD::BRIND: {
     SDValue Target = N->getOperand(1);
     unsigned Opc = Target.getValueType() == MVT::i32 ? PPC::MTCTR : PPC::MTCTR8;
     unsigned Reg = Target.getValueType() == MVT::i32 ? PPC::BCTR : PPC::BCTR8;
     Chain = SDValue(CurDAG->getMachineNode(Opc, dl, MVT::Glue, Target,
                                            Chain), 0);
     return CurDAG->SelectNodeTo(N, Reg, MVT::Other, Chain);
   }
   case PPCISD::TOC_ENTRY: {
+    assert ((PPCSubTarget->isPPC64() || PPCSubTarget->isSVR4ABI()) &&
+            "Only supported for 64-bit ABI and 32-bit SVR4");
     if (PPCSubTarget->isSVR4ABI() && !PPCSubTarget->isPPC64()) {
       SDValue GA = N->getOperand(0);
       return CurDAG->getMachineNode(PPC::LWZtoc, dl, MVT::i32, GA,
                                     N->getOperand(1));
     }
-    assert (PPCSubTarget->isPPC64() &&
-            "Only supported for 64-bit ABI and 32-bit SVR4");
 
     // For medium and large code model, we generate two instructions as
     // described below.  Otherwise we allow SelectCodeCommon to handle this,
     // selecting one of LDtoc, LDtocJTI, and LDtocCPT.
     CodeModel::Model CModel = TM.getCodeModel();
     if (CModel != CodeModel::Medium && CModel != CodeModel::Large)
       break;
 

lib/Target/PowerPC/PPCISelLowering.cpp

SDValue PPCTargetLowering::LowerGlobalTLSAddress(SDValue Op,
   // which is the most useful form.  Eventually support for small and
   // large models could be added if users need it, at the cost of
   // additional complexity.
   GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(Op);
   SDLoc dl(GA);
   const GlobalValue *GV = GA->getGlobal();
   EVT PtrVT = getPointerTy();
   bool is64bit = Subtarget.isPPC64();
+  PICLevel::Level picLevel = getTargetMachine().getPICLevel();
 
   TLSModel::Model Model = getTargetMachine().getTLSModel(GV);
 
   if (Model == TLSModel::LocalExec) {
     SDValue TGAHi = DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0,
                                                PPCII::MO_TPREL_HA);
     SDValue TGALo = DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0,
                                                PPCII::MO_TPREL_LO);
SDValue PPCTargetLowering::LowerGlobalTLSAddress(SDValue Op,
   if (Model == TLSModel::GeneralDynamic) {
     SDValue TGA = DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0, 0);
     SDValue GOTPtr;
     if (is64bit) {
       SDValue GOTReg = DAG.getRegister(PPC::X2, MVT::i64);
       GOTPtr = DAG.getNode(PPCISD::ADDIS_TLSGD_HA, dl, PtrVT,
                                    GOTReg, TGA);
     } else {
+      if (picLevel == PICLevel::Large)
         GOTPtr = DAG.getNode(PPCISD::PPC32_PICGOT, dl, PtrVT);
+      else
+        GOTPtr = DAG.getNode(PPCISD::GlobalBaseReg, dl, PtrVT);
     }
     SDValue GOTEntry = DAG.getNode(PPCISD::ADDI_TLSGD_L, dl, PtrVT,
                                    GOTPtr, TGA);
 
     // We need a chain node, and don't have one handy.  The underlying
     // call has no side effects, so using the function entry node
     // suffices.
     SDValue Chain = DAG.getEntryNode();
SDValue PPCTargetLowering::LowerGlobalTLSAddress(SDValue Op,
   if (Model == TLSModel::LocalDynamic) {
     SDValue TGA = DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0, 0);
     SDValue GOTPtr;
     if (is64bit) {
       SDValue GOTReg = DAG.getRegister(PPC::X2, MVT::i64);
       GOTPtr = DAG.getNode(PPCISD::ADDIS_TLSLD_HA, dl, PtrVT,
                            GOTReg, TGA);
     } else {
+      if (picLevel == PICLevel::Large)
         GOTPtr = DAG.getNode(PPCISD::PPC32_PICGOT, dl, PtrVT);
+      else
+        GOTPtr = DAG.getNode(PPCISD::GlobalBaseReg, dl, PtrVT);
     }
     SDValue GOTEntry = DAG.getNode(PPCISD::ADDI_TLSLD_L, dl, PtrVT,
                                    GOTPtr, TGA);
 
     // We need a chain node, and don't have one handy.  The underlying
     // call has no side effects, so using the function entry node
     // suffices.
     SDValue Chain = DAG.getEntryNode();

lib/Target/PowerPC/PPCInstrInfo.td

let isCodeGenOnly = 1 in {
                                 "bcctr 4, $bi, 0", IIC_BrB, []>;
     }
   }
 }
 
 let Defs = [LR] in
   def MovePCtoLR : Pseudo<(outs), (ins), "#MovePCtoLR", []>,
                    PPC970_Unit_BRU;
+let Defs = [LR] in
+  def MoveGOTtoLR : Pseudo<(outs), (ins), "#MoveGOTtoLR", []>,
+                    PPC970_Unit_BRU;
 
 let isBranch = 1, isTerminator = 1, hasCtrlDep = 1, PPC970_Unit = 7 in {
   let isBarrier = 1 in {
   def B   : IForm<18, 0, 0, (outs), (ins directbrtarget:$dst),
                   "b $dst", IIC_BrB,
                   [(br bb:$dst)]>;
   def BA  : IForm<18, 1, 0, (outs), (ins absdirectbrtarget:$dst),
                   "ba $dst", IIC_BrB, []>;
def ADDIdtprelL32 : Pseudo<(outs gprc:$rD), (ins gprc_nor0:$reg, s16imm:$disp),
                              (PPCaddiDtprelL i32:$reg, tglobaltlsaddr:$disp))]>;
 def ADDISdtprelHA32 : Pseudo<(outs gprc:$rD), (ins gprc_nor0:$reg, s16imm:$disp),
                             "#ADDISdtprelHA32",
                             [(set i32:$rD,
                               (PPCaddisDtprelHA i32:$reg,
                                                 tglobaltlsaddr:$disp))]>;
 
 // Support for Position-independent code
-def LWZtoc: Pseudo<(outs gprc:$rD), (ins tocentry32:$disp, gprc:$reg),
+def LWZtoc : Pseudo<(outs gprc:$rD), (ins tocentry32:$disp, gprc:$reg),
                    "#LWZtoc",
                    [(set i32:$rD,
                       (PPCtoc_entry tglobaladdr:$disp, i32:$reg))]>;
 // Get Global (GOT) Base Register offset, from the word immediately preceding
 // the function label.
-def GetGBRO:  Pseudo<(outs gprc:$rT), (ins gprc:$rI), "#GetGBRO", []>;
-// Update the Global(GOT) Base Register with the above offset.
-def UpdateGBR:  Pseudo<(outs gprc:$rT), (ins gprc:$rI), "#UpdateGBR", []>;
+def UpdateGBR : Pseudo<(outs gprc:$rD, gprc:$rT), (ins gprc:$rI), "#UpdateGBR", []>;
 
 
 // Standard shifts.  These are represented separately from the real shifts above
 // so that we can distinguish between shifts that allow 5-bit and 6-bit shift
 // amounts.
 def : Pat<(sra i32:$rS, i32:$rB),
           (SRAW $rS, $rB)>;
 def : Pat<(srl i32:$rS, i32:$rB),

 defm : TrapExtendedMnemonic<"ne", 24>;
 defm : TrapExtendedMnemonic<"ng", 20>;
 defm : TrapExtendedMnemonic<"llt", 2>;
 defm : TrapExtendedMnemonic<"lle", 6>;
 defm : TrapExtendedMnemonic<"lge", 5>;
 defm : TrapExtendedMnemonic<"lgt", 1>;
 defm : TrapExtendedMnemonic<"lnl", 5>;
 defm : TrapExtendedMnemonic<"lng", 6>;
 defm : TrapExtendedMnemonic<"u", 31>;

test/CodeGen/PowerPC/ppc32-pic.ll

-; RUN: llc < %s -mtriple=powerpc-unknown-linux-gnu -relocation-model=pic | FileCheck %s
-@foobar = common global i32 0, align 4
+; RUN: llc < %s -mtriple=powerpc-unknown-linux-gnu -relocation-model=pic -pic-level=small | FileCheck -check-prefix=SMALL-BSS %s
+; RUN: llc < %s -mtriple=powerpc-unknown-linux-gnu -relocation-model=pic -pic-level=large  | FileCheck -check-prefix=LARGE-BSS %s
+@bar = common global i32 0, align 4
 
 define i32 @foo() {
 entry:
-  %0 = load i32* @foobar, align 4
+  %0 = load i32* @bar, align 4
   ret i32 %0
 }
 
-; CHECK:       [[POFF:\.L[0-9]+\$poff]]:
-; CHECK-NEXT:    .long .L.TOC.-[[PB:\.L[0-9]+\$pb]]
-; CHECK-NEXT:  foo:
-; CHECK:         bl [[PB]]
-; CHECK-NEXT:  [[PB]]:
-; CHECK:         mflr 30
-; CHECK:         lwz [[REG:[0-9]+]], [[POFF]]-[[PB]](30)
-; CHECK-NEXT:    add 30, [[REG]], 30
-; CHECK:         lwz [[VREG:[0-9]+]], [[VREF:\.LC[0-9]+]]-.L.TOC.(30)
-; CHECK:         lwz {{[0-9]+}}, 0([[VREG]])
-; CHECK:       [[VREF]]:
-; CHECK-NEXT:    .long foobar
+; SMALL-BSS-LABEL:foo:
+; SMALL-BSS:         bl _GLOBAL_OFFSET_TABLE_@local-4
+; SMALL-BSS:         mflr 30
+; SMALL-BSS:         lwz [[VREG:[0-9]+]], bar@GOT(30)
+; SMALL-BSS:         lwz {{[0-9]+}}, 0([[VREG]])
+; LARGE-BSS:       [[POFF:\.L[0-9]+\$poff]]:
+; LARGE-BSS-NEXT:    .long .LTOC.-[[PB:\.L[0-9]+\$pb]]
+; LARGE-BSS-NEXT:  foo:
+; LARGE-BSS:         bl [[PB]]
+; LARGE-BSS-NEXT:  [[PB]]:
+; LARGE-BSS:         mflr 30
+; LARGE-BSS:         lwz [[REG:[0-9]+]], [[POFF]]-[[PB]](30)
+; LARGE-BSS-NEXT:    add 30, [[REG]], 30
+; LARGE-BSS:         lwz [[VREG:[0-9]+]], [[VREF:\.LC[0-9]+]]-.LTOC.(30)
+; LARGE-BSS:         lwz {{[0-9]+}}, 0([[VREG]])
+; LARGE-BSS:       [[VREF]]:
+; LARGE-BSS-NEXT:    .long bar

test/CodeGen/PowerPC/sections.ll

 ; Test to make sure that bss sections are printed with '.section' directive.
 ; RUN: llc < %s -mtriple=powerpc-unknown-linux-gnu | FileCheck %s
 ; RUN: llc < %s -mtriple=powerpc-unknown-linux-gnu -relocation-model=pic | FileCheck %s -check-prefix=PIC
+; RUN: llc < %s -mtriple=powerpc-unknown-linux-gnu -relocation-model=pic -pic-level=large| FileCheck %s -check-prefix=LARGE-PIC
 
 @A = global i32 0
 
 ; CHECK:  .section  .bss,"aw",@nobits
 ; CHECK:  .globl A
-
-; PIC:    .section  .got2,"aw",@progbits
 ; PIC:    .section  .bss,"aw",@nobits
 ; PIC:    .globl A
+; LARGE-PIC:    .section  .got2,"aw",@progbits
+; LARGE-PIC:    .section  .bss,"aw",@nobits
+; LARGE-PIC:    .globl A

test/CodeGen/PowerPC/tls-pic.ll

 ; OPT0-LABEL: main:
 ; OPT0:      addis [[REG:[0-9]+]], 2, a@got@tlsld@ha
 ; OPT0-NEXT: addi 3, [[REG]], a@got@tlsld@l
 ; OPT0:      bl __tls_get_addr(a@tlsld)
 ; OPT0-NEXT: nop
 ; OPT0:      addis [[REG2:[0-9]+]], 3, a@dtprel@ha
 ; OPT0-NEXT: addi {{[0-9]+}}, [[REG2]], a@dtprel@l
 ; OPT0-32-LABEL: main
-; OPT0-32:        addi {{[0-9]+}}, {{[0-9]+}}, a@got@tlsld
+; OPT0-32:        addi 3, {{[0-9]+}}, a@got@tlsld
 ; OPT0-32:        bl __tls_get_addr(a@tlsld)@PLT
 ; OPT0-32:        addis [[REG:[0-9]+]], 3, a@dtprel@ha
 ; OPT0-32-NEXT:   addi  {{[0-9]+}}, [[REG]], a@dtprel@l
 ; OPT1-32-LABEL: main
 ; OPT1-32:        addi 3, {{[0-9]+}}, a@got@tlsld
 ; OPT1-32:        bl __tls_get_addr(a@tlsld)@PLT
 ; OPT1-32:        addis [[REG:[0-9]+]], 3, a@dtprel@ha
 ; OPT1-32-NEXT:   addi  {{[0-9]+}}, [[REG]], a@dtprel@l