[ARM] Add support for embedded position-independent code

[olista01]

Summary

This patch adds support for some new relocation models to the ARM
backend:

• Read-only position independence (ROPI): Code and read-only data is accessed PC-relative. The offsets between all code and RO data sections are known at static link time. This does not affect read-write data.
• Read-write position independence (RWPI): Read-write data is accessed relative to the static base register (r9). The offsets between all writeable data sections are known at static link time. This does not affect read-only data.

These two modes are independent (they specify how different objects
should be addressed), so they can be used individually or together. They
are otherwise the same as the "static" relocation model, and are not
compatible with SysV-style PIC using a global offset table.

These modes are normally used by bare-metal systems or systems with
small real-time operating systems. They are designed to avoid the need
for a dynamic linker, the only initialisation required is setting r9 to
an appropriate value for RWPI code.

I have only added support to SelectionDAG, not FastISel, because
FastISel is currently disabled for bare-metal targets where these modes
would be used.

[t.p.northover]

A surprisingly simple addition!

I see you've skipped SjLj exceptions and stack guards support. I think this is fine, but could you put "unsupported" assertions in at least the stack guard code (*InstrInfo.cpp)? I have less worries about SjLj because no-one should be using that voluntarily anyway.

Similarly, could we have an assertion on non-ELF targets about RWPI (in getEffectiveRelocModel or something)? It looks to me like ROPI would work but MachO certainly doesn't have the required relocations for RWPI and if COFF has them, they're not supported yet.

You also seem to have no tests for the build attributes?

test/CodeGen/ARM/arm-position-independence-jump-table.ll

4–8

Have you tried disabling machine block placement (-disable-block-placement) and/or other things that mess around with the code?

If that fails, it would be more efficient to only run llc once (to a temporary file) and then FileCheck that repeatedly:

; RUN: llc <whatever> -o %t
; RUN: FileCheck %s --check-prefix=Whatever < %t
...

[t.p.northover]

Actually, sorry, there's no ROPI support in LowerGlobalAddressDarwin (or whatever) so the assertion should cover both on non-ELF.

[olista01]

• Added assertions for unsupported object formats and features
• Added tests for build attributes
• Simplified jump table test

[weimingz]

Thanks Oliver!

I reviewed the ARMISelLowering part and it LGTM.

lib/Target/ARM/ARMAsmPrinter.cpp

728

Nitpick: period at end of comment? same for line 738, 744 etc.

[olista01]

Added periods at ends of comments.

[t.p.northover]

Thanks Oliver! This looks fine to me.

[eugenis]

llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp

2804 ↗

(On Diff #67175)

What if GV points inside GA->getBaseObject() with non-zero offset?
See https://llvm.org/bugs/show_bug.cgi?id=31896

[eugenis]

llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp

2804 ↗

(On Diff #67175)

Oh, and even if there is no offset, this is still wrong, because the alias may have different linkage and visibility compared to the aliasee.

[eugenis]

Please see https://reviews.llvm.org/D29740

include/llvm/CodeGen/CommandFlags.h

 cl::opt<Reloc::Model> RelocModel(
     "relocation-model", cl::desc("Choose relocation model"),
     cl::values(
         clEnumValN(Reloc::Static, "static", "Non-relocatable code"),
         clEnumValN(Reloc::PIC_, "pic",
                    "Fully relocatable, position independent code"),
         clEnumValN(Reloc::DynamicNoPIC, "dynamic-no-pic",
                    "Relocatable external references, non-relocatable code"),
+        clEnumValN(Reloc::ROPI, "ropi",
+                   "Code and read-only data relocatable, accessed PC-relative"),
+        clEnumValN(Reloc::RWPI, "rwpi",
+                   "Read-write data relocatable, accessed relative to static base"),
+        clEnumValN(Reloc::ROPI_RWPI, "ropi-rwpi",
+                   "Combination of ropi and rwpi"),
         clEnumValEnd));
 
 static inline Optional<Reloc::Model> getRelocModel() {
   if (RelocModel.getNumOccurrences()) {
     Reloc::Model R = RelocModel;
     return R;
   }
   return None;

include/llvm/Support/CodeGen.h

 
 #ifndef LLVM_SUPPORT_CODEGEN_H
 #define LLVM_SUPPORT_CODEGEN_H
 
 namespace llvm {
 
   // Relocation model types.
   namespace Reloc {
-  enum Model { Static, PIC_, DynamicNoPIC };
+  enum Model { Static, PIC_, DynamicNoPIC, ROPI, RWPI, ROPI_RWPI };
   }
 
   // Code model types.
   namespace CodeModel {
     // Sync changes with CodeGenCWrappers.h.
     enum Model { Default, JITDefault, Small, Kernel, Medium, Large };
   }
 

lib/Target/ARM/ARMAsmPrinter.cpp

else if (STI.hasVFP3())
                      ? (STI.hasFP16() ? ARM::FK_VFPV3XD_FP16 : ARM::FK_VFPV3XD)
                      : (STI.hasFP16() ? ARM::FK_VFPV3_D16_FP16 : ARM::FK_VFPV3_D16))
                   // -d16
                   : (STI.hasFP16() ? ARM::FK_VFPV3_FP16 : ARM::FK_VFPV3));
     else if (STI.hasVFP2())
       ATS.emitFPU(ARM::FK_VFPV2);
   }
 
+  // RW data addressing
   if (isPositionIndependent()) {
-    // PIC specific attributes.
     ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_RW_data,
                       ARMBuildAttrs::AddressRWPCRel);
+  } else if (STI.isRWPI()) {
+    // RWPI specific attributes.
+    ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_RW_data,
+                      ARMBuildAttrs::AddressRWSBRel);
+  }
+
+  // RO data addressing
+  if (isPositionIndependent() || STI.isROPI()) {
     ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_RO_data,
                       ARMBuildAttrs::AddressROPCRel);
+  }
+
+  // GOT use
+  if (isPositionIndependent()) {
     ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_GOT_use,
                       ARMBuildAttrs::AddressGOT);
   } else {
-    // Allow direct addressing of imported data for all other relocation models.
     ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_GOT_use,
                       ARMBuildAttrs::AddressDirect);
   }
 
   // Signal various FP modes.
   if (!TM.Options.UnsafeFPMath) {
     ATS.emitAttribute(ARMBuildAttrs::ABI_FP_denormal,
                       ARMBuildAttrs::IEEEDenormals);
if (const Module *SourceModule = MMI->getModule()) {
         assert((EnumWidth == 1 || EnumWidth == 4) &&
                "Minimum enum width must be 1 or 4 bytes");
         int EnumBuildAttr = EnumWidth == 1 ? 1 : 2;
         ATS.emitAttribute(ARMBuildAttrs::ABI_enum_size, EnumBuildAttr);
       }
     }
   }
 
-  // TODO: We currently only support either reserving the register, or treating
-  // it as another callee-saved register, but not as SB or a TLS pointer; It
-  // would instead be nicer to push this from the frontend as metadata, as we do
-  // for the wchar and enum size tags
-  if (STI.isR9Reserved())
-    ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_R9_use, ARMBuildAttrs::R9Reserved);
+  // We currently do not support using R9 as the TLS pointer.
+  if (STI.isRWPI())
+    ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_R9_use,
+                      ARMBuildAttrs::R9IsSB);
+  else if (STI.isR9Reserved())
+    ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_R9_use,
+                      ARMBuildAttrs::R9Reserved);
   else
-    ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_R9_use, ARMBuildAttrs::R9IsGPR);
+    ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_R9_use,
+                      ARMBuildAttrs::R9IsGPR);
 
   if (STI.hasTrustZone() && STI.hasVirtualization())
     ATS.emitAttribute(ARMBuildAttrs::Virtualization_use,
                       ARMBuildAttrs::AllowTZVirtualization);
   else if (STI.hasTrustZone())
     ATS.emitAttribute(ARMBuildAttrs::Virtualization_use,
                       ARMBuildAttrs::AllowTZ);
   else if (STI.hasVirtualization())
getModifierVariantKind(ARMCP::ARMCPModifier Modifier) {
   case ARMCP::no_modifier:
     return MCSymbolRefExpr::VK_None;
   case ARMCP::TLSGD:
     return MCSymbolRefExpr::VK_TLSGD;
   case ARMCP::TPOFF:
     return MCSymbolRefExpr::VK_TPOFF;
   case ARMCP::GOTTPOFF:
     return MCSymbolRefExpr::VK_GOTTPOFF;
+  case ARMCP::SBREL:
+    return MCSymbolRefExpr::VK_ARM_SBREL;
   case ARMCP::GOT_PREL:
     return MCSymbolRefExpr::VK_ARM_GOT_PREL;
   case ARMCP::SECREL:
     return MCSymbolRefExpr::VK_SECREL;
   }
   llvm_unreachable("Invalid ARMCPModifier!");
 }
 
for (unsigned i = 0, e = JTBBs.size(); i != e; ++i) {
     //
     // For example, a table with entries jumping to basic blocks BB0 and BB1
     // would look like:
     // LJTI_0_0:
     //    .word (LBB0 - LJTI_0_0)
     //    .word (LBB1 - LJTI_0_0)
     const MCExpr *Expr = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
 
-    if (isPositionIndependent())
+    if (isPositionIndependent() || Subtarget->isROPI())
       Expr = MCBinaryExpr::createSub(Expr, MCSymbolRefExpr::create(JTISymbol,
                                                                    OutContext),
                                      OutContext);
     // If we're generating a table of Thumb addresses in static relocation
     // model, we need to add one to keep interworking correctly.
     else if (AFI->isThumbFunction())
       Expr = MCBinaryExpr::createAdd(Expr, MCConstantExpr::create(1,OutContext),
                                      OutContext);

lib/Target/ARM/ARMBaseInstrInfo.cpp

bool ARMBaseInstrInfo::verifyInstruction(const MachineInstr &MI,
   return true;
 }
 
 // LoadStackGuard has so far only been implemented for MachO. Different code
 // sequence is needed for other targets.
 void ARMBaseInstrInfo::expandLoadStackGuardBase(MachineBasicBlock::iterator MI,
                                                 unsigned LoadImmOpc,
                                                 unsigned LoadOpc) const {
+  assert(!Subtarget.isROPI() && !Subtarget.isRWPI() &&
+         "ROPI/RWPI not currently supported with stack guard");
+
   MachineBasicBlock &MBB = *MI->getParent();
   DebugLoc DL = MI->getDebugLoc();
   unsigned Reg = MI->getOperand(0).getReg();
   const GlobalValue *GV =
       cast<GlobalValue>((*MI->memoperands_begin())->getValue());
   MachineInstrBuilder MIB;
 
   BuildMI(MBB, MI, DL, get(LoadImmOpc), Reg)

lib/Target/ARM/ARMConstantPoolValue.h

namespace ARMCP {
 
   enum ARMCPModifier {
     no_modifier, /// None
     TLSGD,       /// Thread Local Storage (General Dynamic Mode)
     GOT_PREL,    /// Global Offset Table, PC Relative
     GOTTPOFF,    /// Global Offset Table, Thread Pointer Offset
     TPOFF,       /// Thread Pointer Offset
     SECREL,      /// Section Relative (Windows TLS)
+    SBREL,       /// Static Base Relative (RWPI)
   };
 }
 
 /// ARMConstantPoolValue - ARM specific constantpool value. This is used to
 /// represent PC-relative displacement between the address of the load
 /// instruction and the constant being loaded, i.e. (&GV-(LPIC+8)).
 class ARMConstantPoolValue : public MachineConstantPoolValue {
   unsigned LabelId;        // Label id of the load.

lib/Target/ARM/ARMConstantPoolValue.cpp

const char *ARMConstantPoolValue::getModifierText() const {
   case ARMCP::TLSGD:
     return "tlsgd";
   case ARMCP::GOT_PREL:
     return "GOT_PREL";
   case ARMCP::GOTTPOFF:
     return "gottpoff";
   case ARMCP::TPOFF:
     return "tpoff";
+  case ARMCP::SBREL:
+    return "SBREL";
   case ARMCP::SECREL:
     return "secrel32";
   }
   llvm_unreachable("Unknown modifier!");
 }
 
 int ARMConstantPoolValue::getExistingMachineCPValue(MachineConstantPool *CP,
                                                     unsigned Alignment) {

lib/Target/ARM/ARMFastISel.cpp

 bool ARMFastISel::isPositionIndependent() const {
   return TLI.isPositionIndependent();
 }
 
 unsigned ARMFastISel::ARMMaterializeGV(const GlobalValue *GV, MVT VT) {
   // For now 32-bit only.
   if (VT != MVT::i32 || GV->isThreadLocal()) return 0;
 
+  // ROPI/RWPI not currently supported
+  if (Subtarget->isROPI() || Subtarget->isRWPI())
+    return 0;
+
   bool IsIndirect = Subtarget->isGVIndirectSymbol(GV);
   const TargetRegisterClass *RC = isThumb2 ? &ARM::rGPRRegClass
                                            : &ARM::GPRRegClass;
   unsigned DestReg = createResultReg(RC);
 
   // FastISel TLS support on non-MachO is broken, punt to SelectionDAG.
   const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
   bool IsThreadLocal = GVar && GVar->isThreadLocal();

lib/Target/ARM/ARMISelLowering.cpp

SDValue ARMTargetLowering::LowerBlockAddress(SDValue Op,
                                              SelectionDAG &DAG) const {
   MachineFunction &MF = DAG.getMachineFunction();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
   unsigned ARMPCLabelIndex = 0;
   SDLoc DL(Op);
   EVT PtrVT = getPointerTy(DAG.getDataLayout());
   const BlockAddress *BA = cast<BlockAddressSDNode>(Op)->getBlockAddress();
   SDValue CPAddr;
-  bool IsPositionIndependent = isPositionIndependent();
+  bool IsPositionIndependent = isPositionIndependent() || Subtarget->isROPI();
   if (!IsPositionIndependent) {
     CPAddr = DAG.getTargetConstantPool(BA, PtrVT, 4);
   } else {
     unsigned PCAdj = Subtarget->isThumb() ? 4 : 8;
     ARMPCLabelIndex = AFI->createPICLabelUId();
     ARMConstantPoolValue *CPV =
       ARMConstantPoolConstant::Create(BA, ARMPCLabelIndex,
                                       ARMCP::CPBlockAddress, PCAdj);

 }
 
 SDValue ARMTargetLowering::LowerGlobalAddressELF(SDValue Op,
                                                  SelectionDAG &DAG) const {
   EVT PtrVT = getPointerTy(DAG.getDataLayout());
   SDLoc dl(Op);
   const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
   const TargetMachine &TM = getTargetMachine();
+  if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV))
+    GV = GA->getBaseObject();
+  bool IsRO =
+      (isa<GlobalVariable>(GV) && cast<GlobalVariable>(GV)->isConstant()) ||
+      isa<Function>(GV);
   if (isPositionIndependent()) {
     bool UseGOT_PREL = !TM.shouldAssumeDSOLocal(*GV->getParent(), GV);
 
     MachineFunction &MF = DAG.getMachineFunction();
     ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
     unsigned ARMPCLabelIndex = AFI->createPICLabelUId();
     EVT PtrVT = getPointerTy(DAG.getDataLayout());
     SDLoc dl(Op);
if (isPositionIndependent()) {
     SDValue Chain = Result.getValue(1);
     SDValue PICLabel = DAG.getConstant(ARMPCLabelIndex, dl, MVT::i32);
     Result = DAG.getNode(ARMISD::PIC_ADD, dl, PtrVT, Result, PICLabel);
     if (UseGOT_PREL)
       Result =
           DAG.getLoad(PtrVT, dl, Chain, Result,
                       MachinePointerInfo::getGOT(DAG.getMachineFunction()));
     return Result;
+  } else if (Subtarget->isROPI() && IsRO) {
+    // PC-relative
+    SDValue G = DAG.getTargetGlobalAddress(GV, dl, PtrVT);
+    SDValue Result = DAG.getNode(ARMISD::WrapperPIC, dl, PtrVT, G);
+    return Result;
+  } else if (Subtarget->isRWPI() && !IsRO) {
+    // SB-relative
+    ARMConstantPoolValue *CPV =
+      ARMConstantPoolConstant::Create(GV, ARMCP::SBREL);
+    SDValue CPAddr = DAG.getTargetConstantPool(CPV, PtrVT, 4);
+    CPAddr = DAG.getNode(ARMISD::Wrapper, dl, MVT::i32, CPAddr);
+    SDValue G = DAG.getLoad(
+        PtrVT, dl, DAG.getEntryNode(), CPAddr,
+        MachinePointerInfo::getConstantPool(DAG.getMachineFunction()));
+    SDValue SB = DAG.getCopyFromReg(DAG.getEntryNode(), dl, ARM::R9, PtrVT);
+    SDValue Result = DAG.getNode(ISD::ADD, dl, PtrVT, SB, G);
+    return Result;
   }
 
   // If we have T2 ops, we can materialize the address directly via movt/movw
   // pair. This is always cheaper.
   if (Subtarget->useMovt(DAG.getMachineFunction())) {
     ++NumMovwMovt;
     // FIXME: Once remat is capable of dealing with instructions with register
     // operands, expand this into two nodes.
     return DAG.getNode(ARMISD::Wrapper, dl, PtrVT,
                        DAG.getTargetGlobalAddress(GV, dl, PtrVT));
   } else {
     SDValue CPAddr = DAG.getTargetConstantPool(GV, PtrVT, 4);
     CPAddr = DAG.getNode(ARMISD::Wrapper, dl, MVT::i32, CPAddr);
     return DAG.getLoad(
         PtrVT, dl, DAG.getEntryNode(), CPAddr,
         MachinePointerInfo::getConstantPool(DAG.getMachineFunction()));
   }
 }
 
 SDValue ARMTargetLowering::LowerGlobalAddressDarwin(SDValue Op,
                                                     SelectionDAG &DAG) const {
+  assert(!Subtarget->isROPI() && !Subtarget->isRWPI() &&
+         "ROPI/RWPI not currently supported for Darwin");
   EVT PtrVT = getPointerTy(DAG.getDataLayout());
   SDLoc dl(Op);
   const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
 
   if (Subtarget->useMovt(DAG.getMachineFunction()))
     ++NumMovwMovt;
 
   // FIXME: Once remat is capable of dealing with instructions with register
SDValue ARMTargetLowering::LowerGlobalAddressDarwin(SDValue Op,
   return Result;
 }
 
 SDValue ARMTargetLowering::LowerGlobalAddressWindows(SDValue Op,
                                                      SelectionDAG &DAG) const {
   assert(Subtarget->isTargetWindows() && "non-Windows COFF is not supported");
   assert(Subtarget->useMovt(DAG.getMachineFunction()) &&
          "Windows on ARM expects to use movw/movt");
+  assert(!Subtarget->isROPI() && !Subtarget->isRWPI() &&
+         "ROPI/RWPI not currently supported for Windows");
 
   const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
   const ARMII::TOF TargetFlags =
     (GV->hasDLLImportStorageClass() ? ARMII::MO_DLLIMPORT : ARMII::MO_NO_FLAG);
   EVT PtrVT = getPointerTy(DAG.getDataLayout());
   SDValue Result;
   SDLoc DL(Op);
 
SDValue ARMTargetLowering::LowerBR_JT(SDValue Op, SelectionDAG &DAG) const {
   if (Subtarget->isThumb2()) {
     // Thumb2 uses a two-level jump. That is, it jumps into the jump table
     // which does another jump to the destination. This also makes it easier
     // to translate it to TBB / TBH later.
     // FIXME: This might not work if the function is extremely large.
     return DAG.getNode(ARMISD::BR2_JT, dl, MVT::Other, Chain,
                        Addr, Op.getOperand(2), JTI);
   }
-  if (isPositionIndependent()) {
+  if (isPositionIndependent() || Subtarget->isROPI()) {
     Addr =
         DAG.getLoad((EVT)MVT::i32, dl, Chain, Addr,
                     MachinePointerInfo::getJumpTable(DAG.getMachineFunction()));
     Chain = Addr.getValue(1);
     Addr = DAG.getNode(ISD::ADD, dl, PTy, Addr, Table);
     return DAG.getNode(ARMISD::BR_JT, dl, MVT::Other, Chain, Addr, JTI);
   } else {
     Addr =

 //===----------------------------------------------------------------------===//
 
 /// SetupEntryBlockForSjLj - Insert code into the entry block that creates and
 /// registers the function context.
 void ARMTargetLowering::SetupEntryBlockForSjLj(MachineInstr &MI,
                                                MachineBasicBlock *MBB,
                                                MachineBasicBlock *DispatchBB,
                                                int FI) const {
+  assert(!Subtarget->isROPI() && !Subtarget->isRWPI() &&
+         "ROPI/RWPI not currently supported with SjLj");
   const TargetInstrInfo *TII = Subtarget->getInstrInfo();
   DebugLoc dl = MI.getDebugLoc();
   MachineFunction *MF = MBB->getParent();
   MachineRegisterInfo *MRI = &MF->getRegInfo();
   MachineConstantPool *MCP = MF->getConstantPool();
   ARMFunctionInfo *AFI = MF->getInfo<ARMFunctionInfo>();
   const Function *F = MF->getFunction();
 

lib/Target/ARM/ARMSubtarget.h

return TargetTriple.getEnvironment() == Triple::GNUEABIHF ||
            isTargetWindows() || isAAPCS16_ABI();
   }
   bool isTargetAndroid() const { return TargetTriple.isAndroid(); }
 
   bool isAPCS_ABI() const;
   bool isAAPCS_ABI() const;
   bool isAAPCS16_ABI() const;
 
+  bool isROPI() const;
+  bool isRWPI() const;
+
   bool useSoftFloat() const { return UseSoftFloat; }
   bool isThumb() const { return InThumbMode; }
   bool isThumb1Only() const { return InThumbMode && !HasThumb2; }
   bool isThumb2() const { return InThumbMode && HasThumb2; }
   bool hasThumb2() const { return HasThumb2; }
   bool isMClass() const { return ARMProcClass == MClass; }
   bool isRClass() const { return ARMProcClass == RClass; }
   bool isAClass() const { return ARMProcClass == AClass; }

lib/Target/ARM/ARMSubtarget.cpp

void ARMSubtarget::initSubtargetFeatures(StringRef CPU, StringRef FS) {
   }
 
   // NEON f32 ops are non-IEEE 754 compliant. Darwin is ok with it by default.
   const FeatureBitset &Bits = getFeatureBits();
   if ((Bits[ARM::ProcA5] || Bits[ARM::ProcA8]) && // Where this matters
       (Options.UnsafeFPMath || isTargetDarwin()))
     UseNEONForSinglePrecisionFP = true;
 
+  if (isRWPI())
+    ReserveR9 = true;
+
   // FIXME: Teach TableGen to deal with these instead of doing it manually here.
   switch (ARMProcFamily) {
   case Others:
   case CortexA5:
     break;
   case CortexA7:
     LdStMultipleTiming = DoubleIssue;
     break;
bool ARMSubtarget::isAAPCS_ABI() const {
   return TM.TargetABI == ARMBaseTargetMachine::ARM_ABI_AAPCS ||
          TM.TargetABI == ARMBaseTargetMachine::ARM_ABI_AAPCS16;
 }
 bool ARMSubtarget::isAAPCS16_ABI() const {
   assert(TM.TargetABI != ARMBaseTargetMachine::ARM_ABI_UNKNOWN);
   return TM.TargetABI == ARMBaseTargetMachine::ARM_ABI_AAPCS16;
 }
 
+bool ARMSubtarget::isROPI() const {
+  return TM.getRelocationModel() == Reloc::ROPI ||
+         TM.getRelocationModel() == Reloc::ROPI_RWPI;
+}
+bool ARMSubtarget::isRWPI() const {
+  return TM.getRelocationModel() == Reloc::RWPI ||
+         TM.getRelocationModel() == Reloc::ROPI_RWPI;
+}
+
 bool ARMSubtarget::isGVIndirectSymbol(const GlobalValue *GV) const {
   if (!TM.shouldAssumeDSOLocal(*GV->getParent(), GV))
     return true;
 
   // 32 bit macho has no relocation for a-b if a is undefined, even if b is in
   // the section that is being relocated. This means we have to use o load even
   // for GVs that are known to be local to the dso.
   if (isTargetDarwin() && TM.isPositionIndependent() &&

lib/Target/ARM/ARMTargetMachine.cpp

 }
 
 static Reloc::Model getEffectiveRelocModel(const Triple &TT,
                                            Optional<Reloc::Model> RM) {
   if (!RM.hasValue())
     // Default relocation model on Darwin is PIC.
     return TT.isOSBinFormatMachO() ? Reloc::PIC_ : Reloc::Static;
 
+  if (*RM == Reloc::ROPI || *RM == Reloc::RWPI || *RM == Reloc::ROPI_RWPI)
+    assert(TT.isOSBinFormatELF() &&
+           "ROPI/RWPI currently only supported for ELF");
+
   // DynamicNoPIC is only used on darwin.
   if (*RM == Reloc::DynamicNoPIC && !TT.isOSDarwin())
     return Reloc::Static;
 
   return *RM;
 }
 
 /// Create an ARM architecture model.

lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp

if (IsPCRel) {
     case ARM::fixup_arm_thumb_cp:
     case ARM::fixup_arm_thumb_br:
       llvm_unreachable("Unimplemented");
     case ARM::fixup_arm_condbranch:
     case ARM::fixup_arm_uncondbranch:
       Type = ELF::R_ARM_JUMP24;
       break;
     case ARM::fixup_arm_movt_hi16:
+      switch (Modifier) {
+      default: llvm_unreachable("Unsupported Modifier");
+      case MCSymbolRefExpr::VK_None:
         Type = ELF::R_ARM_MOVT_ABS;
         break;
+      case MCSymbolRefExpr::VK_ARM_SBREL:
+        Type = ELF:: R_ARM_MOVT_BREL;
+        break;
+      }
+      break;
     case ARM::fixup_arm_movw_lo16:
+      switch (Modifier) {
+      default: llvm_unreachable("Unsupported Modifier");
+      case MCSymbolRefExpr::VK_None:
         Type = ELF::R_ARM_MOVW_ABS_NC;
         break;
+      case MCSymbolRefExpr::VK_ARM_SBREL:
+        Type = ELF:: R_ARM_MOVW_BREL_NC;
+        break;
+      }
+      break;
     case ARM::fixup_t2_movt_hi16:
       Type = ELF::R_ARM_THM_MOVT_ABS;
       break;
     case ARM::fixup_t2_movw_lo16:
       Type = ELF::R_ARM_THM_MOVW_ABS_NC;
       break;
     }
   }

lib/Target/TargetLoweringObjectFile.cpp

if (!C->needsRelocation()) {
       case 8:  return SectionKind::getMergeableConst8();
       case 16: return SectionKind::getMergeableConst16();
       case 32: return SectionKind::getMergeableConst32();
       default:
         return SectionKind::getReadOnly();
       }
 
     } else {
-      // In static relocation model, the linker will resolve all addresses, so
-      // the relocation entries will actually be constants by the time the app
-      // starts up.  However, we can't put this into a mergable section, because
-      // the linker doesn't take relocations into consideration when it tries to
-      // merge entries in the section.
-      if (ReloModel == Reloc::Static)
+      // In static, ROPI and RWPI relocation models, the linker will resolve
+      // all addresses, so the relocation entries will actually be constants by
+      // the time the app starts up.  However, we can't put this into a
+      // mergable section, because the linker doesn't take relocations into
+      // consideration when it tries to merge entries in the section.
+      if (ReloModel == Reloc::Static || ReloModel == Reloc::ROPI ||
+          ReloModel == Reloc::RWPI || ReloModel == Reloc::ROPI_RWPI)
         return SectionKind::getReadOnly();
 
       // Otherwise, the dynamic linker needs to fix it up, put it in the
       // writable data.rel section.
       return SectionKind::getReadOnlyWithRel();
     }
   }
 

test/CodeGen/ARM/arm-position-independence-jump-table.ll

+; Test for generation of jump table for ropi/rwpi
+
+; RUN: llc -relocation-model=static    -mtriple=armv7a--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=ARM --check-prefix=ARM_ABS
+; RUN: llc -relocation-model=ropi      -mtriple=armv7a--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=ARM --check-prefix=ARM_PC
+; RUN: llc -relocation-model=ropi-rwpi -mtriple=armv7a--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=ARM --check-prefix=ARM_PC
+
+; RUN: llc -relocation-model=static    -mtriple=thumbv7m--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB2
+; RUN: llc -relocation-model=ropi      -mtriple=thumbv7m--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB2
+; RUN: llc -relocation-model=ropi-rwpi -mtriple=thumbv7m--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB2
+
+; RUN: llc -relocation-model=static    -mtriple=thumbv6m--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB1 --check-prefix=THUMB1_ABS
+; RUN: llc -relocation-model=ropi      -mtriple=thumbv6m--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB1 --check-prefix=THUMB1_PC
+; RUN: llc -relocation-model=ropi-rwpi -mtriple=thumbv6m--none-eabi -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB1 --check-prefix=THUMB1_PC
+
+
+declare void @exit0()
+declare void @exit1()
+declare void @exit2()
+declare void @exit3()
+declare void @exit4()
+define void @jump_table(i32 %val) {
+entry:
+  switch i32 %val, label %default [ i32 1, label %lab1
+                                    i32 2, label %lab2
+                                    i32 3, label %lab3
+                                    i32 4, label %lab4 ]
+
+default:
+  tail call void @exit0()
+  ret void
+
+lab1:
+  tail call void @exit1()
+  ret void
+
+lab2:
+  tail call void @exit2()
+  ret void
+
+lab3:
+  tail call void @exit3()
+  ret void
+
+lab4:
+  tail call void @exit4()
+  ret void
+
+; CHECK-LABEL: jump_table:
+
+; ARM: lsl     r[[R_TAB_IDX:[0-9]+]], r{{[0-9]+}}, #2
+; ARM: adr     r[[R_TAB_BASE:[0-9]+]], [[LJTI:\.LJTI[0-9]+_[0-9]+]]
+; ARM_ABS: ldr     pc, [r[[R_TAB_IDX]], r[[R_TAB_BASE]]]
+; ARM_PC:  ldr     r[[R_OFFSET:[0-9]+]], [r[[R_TAB_IDX]], r[[R_TAB_BASE]]]
+; ARM_PC:  add     pc, r[[R_OFFSET]], r[[R_TAB_BASE]]
+; ARM: [[LJTI]]
+; ARM_ABS: .long [[LBB1:\.LBB[0-9]+_[0-9]+]]
+; ARM_ABS: .long [[LBB2:\.LBB[0-9]+_[0-9]+]]
+; ARM_ABS: .long [[LBB3:\.LBB[0-9]+_[0-9]+]]
+; ARM_ABS: .long [[LBB4:\.LBB[0-9]+_[0-9]+]]
+; ARM_PC:  .long [[LBB1:\.LBB[0-9]+_[0-9]+]]-[[LJTI]]
+; ARM_PC:  .long [[LBB2:\.LBB[0-9]+_[0-9]+]]-[[LJTI]]
+; ARM_PC:  .long [[LBB3:\.LBB[0-9]+_[0-9]+]]-[[LJTI]]
+; ARM_PC:  .long [[LBB4:\.LBB[0-9]+_[0-9]+]]-[[LJTI]]
+; ARM: [[LBB1]]
+; ARM-NEXT: b exit1
+; ARM: [[LBB2]]
+; ARM-NEXT: b exit2
+; ARM: [[LBB3]]
+; ARM-NEXT: b exit3
+; ARM: [[LBB4]]
+; ARM-NEXT: b exit4
+
+; THUMB2: [[LCPI:\.LCPI[0-9]+_[0-9]+]]:
+; THUMB2: tbb     [pc, r{{[0-9]+}}]
+; THUMB2: .byte   ([[LBB1:\.LBB[0-9]+_[0-9]+]]-([[LCPI]]+4))/2
+; THUMB2: .byte   ([[LBB2:\.LBB[0-9]+_[0-9]+]]-([[LCPI]]+4))/2
+; THUMB2: .byte   ([[LBB3:\.LBB[0-9]+_[0-9]+]]-([[LCPI]]+4))/2
+; THUMB2: .byte   ([[LBB4:\.LBB[0-9]+_[0-9]+]]-([[LCPI]]+4))/2
+; THUMB2: [[LBB1]]
+; THUMB2-NEXT: b exit1
+; THUMB2: [[LBB2]]
+; THUMB2-NEXT: b exit2
+; THUMB2: [[LBB3]]
+; THUMB2-NEXT: b exit3
+; THUMB2: [[LBB4]]
+; THUMB2-NEXT: b exit4
+
+; THUMB1: lsls    r[[R_TAB_INDEX:[0-9]+]], r{{[0-9]+}}, #2 
+; THUMB1: adr     r[[R_TAB_BASE:[0-9]+]], [[LJTI:\.LJTI[0-9]+_[0-9]+]]
+; THUMB1: ldr     r[[R_BB_ADDR:[0-9]+]], [r[[R_TAB_INDEX]], r[[R_TAB_BASE]]]
+; THUMB1_PC: adds    r[[R_BB_ADDR]], r[[R_BB_ADDR]], r[[R_TAB_BASE]]
+; THUMB1: mov     pc, r[[R_BB_ADDR]]
+; THUMB1: [[LJTI]]
+; THUMB1_ABS: .long [[LBB1:\.LBB[0-9]+_[0-9]+]]+1
+; THUMB1_ABS: .long [[LBB2:\.LBB[0-9]+_[0-9]+]]+1
+; THUMB1_ABS: .long [[LBB3:\.LBB[0-9]+_[0-9]+]]+1
+; THUMB1_ABS: .long [[LBB4:\.LBB[0-9]+_[0-9]+]]+1
+; THUMB1_PC:  .long [[LBB1:\.LBB[0-9]+_[0-9]+]]-[[LJTI]]
+; THUMB1_PC:  .long [[LBB2:\.LBB[0-9]+_[0-9]+]]-[[LJTI]]
+; THUMB1_PC:  .long [[LBB3:\.LBB[0-9]+_[0-9]+]]-[[LJTI]]
+; THUMB1_PC:  .long [[LBB4:\.LBB[0-9]+_[0-9]+]]-[[LJTI]]
+; THUMB1: [[LBB1]]
+; THUMB1-NEXT: bl exit1
+; THUMB1-NEXT: pop
+; THUMB1: [[LBB2]]
+; THUMB1-NEXT: bl exit2
+; THUMB1-NEXT: pop
+; THUMB1: [[LBB3]]
+; THUMB1-NEXT: bl exit3
+; THUMB1-NEXT: pop
+; THUMB1: [[LBB4]]
+; THUMB1-NEXT: bl exit4
+; THUMB1-NEXT: pop
+}

test/CodeGen/ARM/arm-position-independence.ll

+; RUN: llc -relocation-model=static    -mtriple=armv7a--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=ARM_RO_ABS --check-prefix=ARM_RW_ABS
+; RUN: llc -relocation-model=ropi      -mtriple=armv7a--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=ARM_RO_PC  --check-prefix=ARM_RW_ABS
+; RUN: llc -relocation-model=rwpi      -mtriple=armv7a--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=ARM_RO_ABS --check-prefix=ARM_RW_SB
+; RUN: llc -relocation-model=ropi-rwpi -mtriple=armv7a--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=ARM_RO_PC  --check-prefix=ARM_RW_SB
+
+; RUN: llc -relocation-model=static    -mtriple=thumbv7m--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB2_RO_ABS --check-prefix=THUMB2_RW_ABS
+; RUN: llc -relocation-model=ropi      -mtriple=thumbv7m--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB2_RO_PC  --check-prefix=THUMB2_RW_ABS
+; RUN: llc -relocation-model=rwpi      -mtriple=thumbv7m--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB2_RO_ABS  --check-prefix=THUMB2_RW_SB
+; RUN: llc -relocation-model=ropi-rwpi -mtriple=thumbv7m--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB2_RO_PC  --check-prefix=THUMB2_RW_SB
+
+; RUN: llc -relocation-model=static    -mtriple=thumbv6m--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB1_RO_ABS --check-prefix=THUMB1_RW_ABS
+; RUN: llc -relocation-model=ropi      -mtriple=thumbv6m--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB1_RO_PC  --check-prefix=THUMB1_RW_ABS
+; RUN: llc -relocation-model=rwpi      -mtriple=thumbv6m--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB1_RO_ABS --check-prefix=THUMB1_RW_SB
+; RUN: llc -relocation-model=ropi-rwpi -mtriple=thumbv6m--none-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=THUMB1_RO_PC  --check-prefix=THUMB1_RW_SB
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+
+@a = external global i32, align 4
+@b = external constant i32, align 4
+
+define i32 @read() {
+entry:
+  %0 = load i32, i32* @a, align 4
+  ret i32 %0
+; CHECK-LABEL: read:
+
+; ARM_RW_ABS: movw    r[[REG:[0-9]]], :lower16:a
+; ARM_RW_ABS: movt    r[[REG]], :upper16:a
+; ARM_RW_ABS: ldr     r0, [r[[REG]]]
+
+; ARM_RW_SB: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; ARM_RW_SB: ldr     r0, [r9, r[[REG]]]
+
+; THUMB2_RW_ABS: movw    r[[REG:[0-9]]], :lower16:a
+; THUMB2_RW_ABS: movt    r[[REG]], :upper16:a
+; THUMB2_RW_ABS: ldr     r0, [r[[REG]]]
+
+; THUMB2_RW_SB: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB2_RW_SB: ldr.w   r0, [r9, r[[REG]]]
+
+; THUMB1_RW_ABS: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RW_ABS: ldr     r0, [r[[REG]]]
+
+; THUMB1_RW_SB: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RW_SB: mov     r[[REG_SB:[0-9]+]], r9
+; THUMB1_RW_SB: ldr     r0, [r[[REG_SB]], r[[REG]]]
+
+; CHECK: {{(bx lr|pop)}}
+
+; ARM_RW_SB: [[LCPI]]
+; ARM_RW_SB: .long   a(sbrel)
+
+; THUMB2_RW_SB: [[LCPI]]
+; THUMB2_RW_SB: .long   a(sbrel)
+
+; THUMB1_RW_ABS: [[LCPI]]
+; THUMB1_RW_ABS-NEXT: .long a
+
+; THUMB1_RW_SB: [[LCPI]]
+; THUMB1_RW_SB: .long   a(sbrel)
+}
+
+define void @write(i32 %v)  {
+entry:
+  store i32 %v, i32* @a, align 4
+  ret void
+; CHECK-LABEL: write:
+
+; ARM_RW_ABS: movw    r[[REG:[0-9]]], :lower16:a
+; ARM_RW_ABS: movt    r[[REG]], :upper16:a
+; ARM_RW_ABS: str     r0, [r[[REG:[0-9]]]]
+
+; ARM_RW_SB: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; ARM_RW_SB: str     r0, [r9, r[[REG]]]
+
+; THUMB2_RW_ABS: movw    r[[REG:[0-9]]], :lower16:a
+; THUMB2_RW_ABS: movt    r[[REG]], :upper16:a
+; THUMB2_RW_ABS: str     r0, [r[[REG]]]
+
+; THUMB2_RW_SB: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB2_RW_SB: str.w   r0, [r9, r[[REG]]]
+
+; THUMB1_RW_ABS: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RW_ABS: str     r0, [r[[REG]]]
+
+; THUMB1_RW_SB: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RW_SB: mov     r[[REG_SB:[0-9]+]], r9
+; THUMB1_RW_SB: str     r0, [r[[REG_SB]], r[[REG]]]
+
+; CHECK: {{(bx lr|pop)}}
+
+; ARM_RW_SB: [[LCPI]]
+; ARM_RW_SB: .long   a(sbrel)
+
+; THUMB2_RW_SB: [[LCPI]]
+; THUMB2_RW_SB: .long   a(sbrel)
+
+; THUMB1_RW_ABS: [[LCPI]]
+; THUMB1_RW_ABS-NEXT: .long a
+
+; THUMB1_RW_SB: [[LCPI]]
+; THUMB1_RW_SB: .long   a(sbrel)
+}
+
+define i32 @read_const()  {
+entry:
+  %0 = load i32, i32* @b, align 4
+  ret i32 %0
+; CHECK-LABEL: read_const:
+
+; ARM_RO_ABS: movw    r[[reg:[0-9]]], :lower16:b
+; ARM_RO_ABS: movt    r[[reg]], :upper16:b
+; ARM_RO_ABS: ldr     r0, [r[[reg]]]
+
+; ARM_RO_PC: movw    r[[REG:[0-9]]], :lower16:(b-([[LPC:.LPC[0-9]+_[0-9]+]]+8))
+; ARM_RO_PC: movt    r[[REG]], :upper16:(b-([[LPC]]+8))
+; ARM_RO_PC: [[LPC]]:
+; ARM_RO_PC-NEXT: ldr     r0, [pc, r[[REG]]]
+
+; THUMB2_RO_ABS: movw    r[[REG:[0-9]]], :lower16:b
+; THUMB2_RO_ABS: movt    r[[REG]], :upper16:b
+; THUMB2_RO_ABS: ldr     r0, [r[[REG]]]
+
+; THUMB2_RO_PC: movw    r[[REG:[0-9]]], :lower16:(b-([[LPC:.LPC[0-9]+_[0-9]+]]+4))
+; THUMB2_RO_PC: movt    r[[REG]], :upper16:(b-([[LPC]]+4))
+; THUMB2_RO_PC: [[LPC]]:
+; THUMB2_RO_PC-NEXT: add     r[[REG]], pc
+; THUMB2_RO_PC: ldr     r0, [r[[REG]]]
+
+; THUMB1_RO_ABS: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RO_ABS: ldr     r0, [r[[REG]]]
+
+; THUMB1_RO_PC: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RO_PC: [[LPC:.LPC[0-9]+_[0-9]+]]:
+; THUMB1_RO_PC-NEXT: add     r[[REG]], pc
+; THUMB1_RO_PC: ldr     r0, [r[[REG]]]
+
+; CHECK: {{(bx lr|pop)}}
+
+; THUMB1_RO_ABS: [[LCPI]]
+; THUMB1_RO_ABS-NEXT: .long b
+
+; THUMB1_RO_PC: [[LCPI]]
+; THUMB1_RO_PC-NEXT: .long b-([[LPC]]+4)
+}
+
+define i32* @take_addr()  {
+entry:
+  ret i32* @a
+; CHECK-LABEL: take_addr:
+
+; ARM_RW_ABS: movw    r[[REG:[0-9]]], :lower16:a
+; ARM_RW_ABS: movt    r[[REG]], :upper16:a
+
+; ARM_RW_SB: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; ARM_RW_SB: add     r0, r9, r[[REG]]
+
+; THUMB2_RW_ABS: movw    r[[REG:[0-9]]], :lower16:a
+; THUMB2_RW_ABS: movt    r[[REG]], :upper16:a
+
+; THUMB2_RW_SB: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB2_RW_SB: add     r0, r9
+
+; THUMB1_RW_ABS: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+
+; THUMB1_RW_SB: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RW_SB: mov     r[[REG_SB:[0-9]+]], r9
+; THUMB1_RW_SB: adds    r[[REG]], r[[REG_SB]], r[[REG]]
+
+; CHECK: {{(bx lr|pop)}}
+
+; ARM_RW_SB: [[LCPI]]
+; ARM_RW_SB: .long   a(sbrel)
+
+; THUMB2_RW_SB: [[LCPI]]
+; THUMB2_RW_SB: .long   a(sbrel)
+
+; THUMB1_RW_ABS: [[LCPI]]
+; THUMB1_RW_ABS-NEXT: .long a
+
+; THUMB1_RW_SB: [[LCPI]]
+; THUMB1_RW_SB: .long   a(sbrel)
+}
+
+define i32* @take_addr_const()  {
+entry:
+  ret i32* @b
+; CHECK-LABEL: take_addr_const:
+
+; ARM_RO_ABS: movw    r[[REG:[0-9]]], :lower16:b
+; ARM_RO_ABS: movt    r[[REG]], :upper16:b
+
+; ARM_RO_PC: movw    r[[REG:[0-9]]], :lower16:(b-([[LPC:.LPC[0-9]+_[0-9]+]]+8))
+; ARM_RO_PC: movt    r[[REG]], :upper16:(b-([[LPC]]+8))
+; ARM_RO_PC: [[LPC]]:
+; ARM_RO_PC-NEXT: add     r0, pc, r[[REG:[0-9]]]
+
+; THUMB2_RO_ABS: movw    r[[REG:[0-9]]], :lower16:b
+; THUMB2_RO_ABS: movt    r[[REG]], :upper16:b
+
+; THUMB2_RO_PC: movw    r0, :lower16:(b-([[LPC:.LPC[0-9]+_[0-9]+]]+4))
+; THUMB2_RO_PC: movt    r0, :upper16:(b-([[LPC]]+4))
+; THUMB2_RO_PC: [[LPC]]:
+; THUMB2_RO_PC-NEXT: add     r0, pc
+
+; THUMB1_RO_ABS: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+
+; THUMB1_RO_PC: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RO_PC: [[LPC:.LPC[0-9]+_[0-9]+]]:
+; THUMB1_RO_PC-NEXT: add     r[[REG]], pc
+
+; CHECK: {{(bx lr|pop)}}
+
+; THUMB1_RO_ABS: [[LCPI]]
+; THUMB1_RO_ABS-NEXT: .long b
+
+; THUMB1_RO_PC: [[LCPI]]
+; THUMB1_RO_PC-NEXT: .long b-([[LPC]]+4)
+}
+
+define i8* @take_addr_func()  {
+entry:
+  ret i8* bitcast (i8* ()* @take_addr_func to i8*)
+; CHECK-LABEL: take_addr_func:
+
+; ARM_RO_ABS: movw    r[[REG:[0-9]]], :lower16:take_addr_func
+; ARM_RO_ABS: movt    r[[REG]], :upper16:take_addr_func
+
+; ARM_RO_PC: movw    r[[REG:[0-9]]], :lower16:(take_addr_func-([[LPC:.LPC[0-9]+_[0-9]+]]+8))
+; ARM_RO_PC: movt    r[[REG]], :upper16:(take_addr_func-([[LPC]]+8))
+; ARM_RO_PC: [[LPC]]:
+; ARM_RO_PC-NEXT: add     r0, pc, r[[REG:[0-9]]]
+
+; THUMB2_RO_ABS: movw    r[[REG:[0-9]]], :lower16:take_addr_func
+; THUMB2_RO_ABS: movt    r[[REG]], :upper16:take_addr_func
+
+; THUMB2_RO_PC: movw    r0, :lower16:(take_addr_func-([[LPC:.LPC[0-9]+_[0-9]+]]+4))
+; THUMB2_RO_PC: movt    r0, :upper16:(take_addr_func-([[LPC]]+4))
+; THUMB2_RO_PC: [[LPC]]:
+; THUMB2_RO_PC-NEXT: add     r0, pc
+
+; THUMB1_RO_ABS: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+
+; THUMB1_RO_PC: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RO_PC: [[LPC:.LPC[0-9]+_[0-9]+]]:
+; THUMB1_RO_PC-NEXT: add     r[[REG]], pc
+
+; CHECK: {{(bx lr|pop)}}
+
+; THUMB1_RO_ABS: [[LCPI]]
+; THUMB1_RO_ABS-NEXT: .long take_addr_func
+
+; THUMB1_RO_PC: [[LCPI]]
+; THUMB1_RO_PC-NEXT: .long take_addr_func-([[LPC]]+4)
+}
+
+define i8* @block_addr() {
+entry:
+  br label %lab1
+
+lab1:
+  ret i8* blockaddress(@block_addr, %lab1)
+
+; CHECK-LABEL: block_addr:
+
+; ARM_RO_ABS: [[LTMP:.Ltmp[0-9]+]]:
+; ARM_RO_ABS: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+
+; ARM_RO_PC: [[LTMP:.Ltmp[0-9]+]]:
+; ARM_RO_PC: ldr     r[[REG:[0-9]]], [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; ARM_RO_PC: [[LPC:.LPC[0-9]+_[0-9]+]]:
+; ARM_RO_PC: add     r0, pc, r[[REG]]
+
+; THUMB2_RO_ABS: [[LTMP:.Ltmp[0-9]+]]:
+; THUMB2_RO_ABS: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+
+; THUMB2_RO_PC: [[LTMP:.Ltmp[0-9]+]]:
+; THUMB2_RO_PC: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB2_RO_PC: [[LPC:.LPC[0-9]+_[0-9]+]]:
+; THUMB2_RO_PC: add     r0, pc
+
+; THUMB1_RO_ABS: [[LTMP:.Ltmp[0-9]+]]:
+; THUMB1_RO_ABS: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+
+; THUMB1_RO_PC: [[LTMP:.Ltmp[0-9]+]]:
+; THUMB1_RO_PC: ldr     r0, [[LCPI:.LCPI[0-9]+_[0-9]+]]
+; THUMB1_RO_PC: [[LPC:.LPC[0-9]+_[0-9]+]]:
+; THUMB1_RO_PC: add     r0, pc
+
+; CHECK: bx lr
+
+; ARM_RO_ABS: [[LCPI]]
+; ARM_RO_ABS-NEXT: .long   [[LTMP]]
+
+; ARM_RO_PC: [[LCPI]]
+; ARM_RO_PC-NEXT: .long   [[LTMP]]-([[LPC]]+8)
+
+; THUMB2_RO_ABS: [[LCPI]]
+; THUMB2_RO_ABS-NEXT: .long   [[LTMP]]
+
+; THUMB2_RO_PC: [[LCPI]]
+; THUMB2_RO_PC-NEXT: .long   [[LTMP]]-([[LPC]]+4)
+
+; THUMB1_RO_ABS: [[LCPI]]
+; THUMB1_RO_ABS-NEXT: .long   [[LTMP]]
+
+; THUMB1_RO_PC: [[LCPI]]
+; THUMB1_RO_PC-NEXT: .long   [[LTMP]]-([[LPC]]+4)
+}

test/CodeGen/ARM/build-attributes.ll

 ; RUN: llc < %s -mtriple=armv7-none-linux-gnueabi -mcpu=cortex-a7 -mattr=+vfp4,-neon  -enable-unsafe-fp-math -disable-fp-elim -enable-no-infs-fp-math -enable-no-nans-fp-math -fp-contract=fast | FileCheck %s --check-prefix=CORTEX-A7-FPUV4-FAST
 ; RUN: llc < %s -mtriple=armv7-none-linux-gnueabi -mcpu=cortex-a7 -mattr=+vfp4,,+d16,-neon | FileCheck %s --check-prefix=CORTEX-A7-FPUV4
 ; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+strict-align -relocation-model=pic | FileCheck %s --check-prefix=RELOC-PIC
 ; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+strict-align -relocation-model=static | FileCheck %s --check-prefix=RELOC-OTHER
 ; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+strict-align -relocation-model=dynamic-no-pic | FileCheck %s --check-prefix=RELOC-OTHER
 ; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+strict-align | FileCheck %s --check-prefix=RELOC-OTHER
 ; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+strict-align | FileCheck %s --check-prefix=PCS-R9-USE
 ; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+reserve-r9,+strict-align | FileCheck %s --check-prefix=PCS-R9-RESERVE
+; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+strict-align -relocation-model=ropi | FileCheck %s --check-prefix=RELOC-ROPI
+; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+strict-align -relocation-model=rwpi | FileCheck %s --check-prefix=RELOC-RWPI
+; RUN: llc < %s -mtriple=arm-none-linux-gnueabi -mattr=+strict-align -relocation-model=ropi-rwpi | FileCheck %s --check-prefix=RELOC-ROPI-RWPI
 
 ; ARMv8.1a (AArch32)
 ; RUN: llc < %s -mtriple=armv8.1a-none-linux-gnueabi | FileCheck %s --check-prefix=NO-STRICT-ALIGN
 ; RUN: llc < %s -mtriple=armv8.1a-none-linux-gnueabi -mattr=+strict-align | FileCheck %s --check-prefix=STRICT-ALIGN
 ; RUN: llc < %s -mtriple=armv8.1a-none-linux-gnueabi | FileCheck %s --check-prefix=NO-STRICT-ALIGN
 ; ARMv8a (AArch32)
 ; RUN: llc < %s -mtriple=armv8-none-linux-gnueabi -mcpu=cortex-a32 | FileCheck %s --check-prefix=NO-STRICT-ALIGN
 ; RUN: llc < %s -mtriple=armv8-none-linux-gnueabi -mcpu=cortex-a32 -mattr=+strict-align | FileCheck %s --check-prefix=STRICT-ALIGN

 ; GENERIC-ARMV8_1-A-FAST-NOT:  .eabi_attribute 21
 ; GENERIC-ARMV8_1-A-FAST-NOT:  .eabi_attribute 22
 ; GENERIC-ARMV8_1-A-FAST:  .eabi_attribute 23, 1
 
 ; RELOC-PIC:  .eabi_attribute 15, 1
 ; RELOC-PIC:  .eabi_attribute 16, 1
 ; RELOC-PIC:  .eabi_attribute 17, 2
 ; RELOC-OTHER:  .eabi_attribute 17, 1
+; RELOC-ROPI-NOT:  .eabi_attribute 15,
+; RELOC-ROPI:      .eabi_attribute 16, 1
+; RELOC-ROPI:      .eabi_attribute 17, 1
+; RELOC-RWPI:      .eabi_attribute 15, 2
+; RELOC-RWPI-NOT:  .eabi_attribute 16,
+; RELOC-RWPI:      .eabi_attribute 17, 1
+; RELOC-ROPI-RWPI: .eabi_attribute 15, 2
+; RELOC-ROPI-RWPI: .eabi_attribute 16, 1
+; RELOC-ROPI-RWPI:  .eabi_attribute 17, 1
 
 ; PCS-R9-USE:  .eabi_attribute 14, 0
 ; PCS-R9-RESERVE:  .eabi_attribute 14, 3
 
 define i32 @f(i64 %z) {
     ret i32 0
 }