[arm-fast-isel] Add support for ELF PIC.
This is a preliminary step towards ELF support; currently ARMFastISel hasn't
been used for ELF object files yet.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164759 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMInstrInfo.cpp b/lib/Target/ARM/ARMInstrInfo.cpp
index 31b0c41..e621877 100644
--- a/lib/Target/ARM/ARMInstrInfo.cpp
+++ b/lib/Target/ARM/ARMInstrInfo.cpp
@@ -13,13 +13,17 @@
#include "ARMInstrInfo.h"
#include "ARM.h"
+#include "ARMConstantPoolValue.h"
#include "ARMMachineFunctionInfo.h"
+#include "ARMTargetMachine.h"
#include "MCTargetDesc/ARMAddressingModes.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
+#include "llvm/Function.h"
+#include "llvm/GlobalVariable.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCInst.h"
using namespace llvm;
@@ -84,3 +88,61 @@
return 0;
}
+
+namespace {
+ /// ARMCGBR - Create Global Base Reg pass. This initializes the PIC
+ /// global base register for ARM ELF.
+ struct ARMCGBR : public MachineFunctionPass {
+ static char ID;
+ ARMCGBR() : MachineFunctionPass(ID) {}
+
+ virtual bool runOnMachineFunction(MachineFunction &MF) {
+ ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+ if (AFI->getGlobalBaseReg() == 0)
+ return false;
+
+ const ARMTargetMachine *TM =
+ static_cast<const ARMTargetMachine *>(&MF.getTarget());
+ if (TM->getRelocationModel() != Reloc::PIC_)
+ return false;
+
+ LLVMContext* Context = &MF.getFunction()->getContext();
+ GlobalValue *GV = new GlobalVariable(Type::getInt32Ty(*Context), false,
+ GlobalValue::ExternalLinkage, 0,
+ "_GLOBAL_OFFSET_TABLE_");
+ unsigned Id = AFI->createPICLabelUId();
+ ARMConstantPoolValue *CPV = ARMConstantPoolConstant::Create(GV, Id);
+ unsigned Align = TM->getTargetData()->getPrefTypeAlignment(GV->getType());
+ unsigned Idx = MF.getConstantPool()->getConstantPoolIndex(CPV, Align);
+
+ MachineBasicBlock &FirstMBB = MF.front();
+ MachineBasicBlock::iterator MBBI = FirstMBB.begin();
+ DebugLoc DL = FirstMBB.findDebugLoc(MBBI);
+ unsigned GlobalBaseReg = AFI->getGlobalBaseReg();
+ unsigned Opc = TM->getSubtarget<ARMSubtarget>().isThumb2() ?
+ ARM::t2LDRpci : ARM::LDRcp;
+ const TargetInstrInfo &TII = *TM->getInstrInfo();
+ MachineInstrBuilder MIB = BuildMI(FirstMBB, MBBI, DL,
+ TII.get(Opc), GlobalBaseReg)
+ .addConstantPoolIndex(Idx);
+ if (Opc == ARM::LDRcp)
+ MIB.addImm(0);
+ AddDefaultPred(MIB);
+
+ return true;
+ }
+
+ virtual const char *getPassName() const {
+ return "ARM PIC Global Base Reg Initialization";
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ MachineFunctionPass::getAnalysisUsage(AU);
+ }
+ };
+}
+
+char ARMCGBR::ID = 0;
+FunctionPass*
+llvm::createARMGlobalBaseRegPass() { return new ARMCGBR(); }