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//===- AArch64RegisterInfo.cpp - AArch64 Register Information -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the AArch64 implementation of the TargetRegisterInfo class.
//
//===----------------------------------------------------------------------===//
#include "AArch64RegisterInfo.h"
#include "AArch64FrameLowering.h"
#include "AArch64MachineFunctionInfo.h"
#include "AArch64TargetMachine.h"
#include "MCTargetDesc/AArch64MCTargetDesc.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/ADT/BitVector.h"
#define GET_REGINFO_TARGET_DESC
#include "AArch64GenRegisterInfo.inc"
using namespace llvm;
AArch64RegisterInfo::AArch64RegisterInfo(const AArch64InstrInfo &tii,
const AArch64Subtarget &sti)
: AArch64GenRegisterInfo(AArch64::X30), TII(tii) {
}
const uint16_t *
AArch64RegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
return CSR_PCS_SaveList;
}
const uint32_t*
AArch64RegisterInfo::getCallPreservedMask(CallingConv::ID) const {
return CSR_PCS_RegMask;
}
const uint32_t *AArch64RegisterInfo::getTLSDescCallPreservedMask() const {
return TLSDesc_RegMask;
}
const TargetRegisterClass *
AArch64RegisterInfo::getCrossCopyRegClass(const TargetRegisterClass *RC) const {
if (RC == &AArch64::FlagClassRegClass)
return &AArch64::GPR64RegClass;
return RC;
}
BitVector
AArch64RegisterInfo::getReservedRegs(const MachineFunction &MF) const {
BitVector Reserved(getNumRegs());
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
Reserved.set(AArch64::XSP);
Reserved.set(AArch64::WSP);
Reserved.set(AArch64::XZR);
Reserved.set(AArch64::WZR);
if (TFI->hasFP(MF)) {
Reserved.set(AArch64::X29);
Reserved.set(AArch64::W29);
}
return Reserved;
}
void
AArch64RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator MBBI,
int SPAdj, RegScavenger *RS) const {
assert(SPAdj == 0 && "Cannot deal with nonzero SPAdj yet");
MachineInstr &MI = *MBBI;
MachineBasicBlock &MBB = *MI.getParent();
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo *MFI = MF.getFrameInfo();
const AArch64FrameLowering *TFI =
static_cast<const AArch64FrameLowering *>(MF.getTarget().getFrameLowering());
unsigned i = 0;
while (!MI.getOperand(i).isFI()) {
++i;
assert(i < MI.getNumOperands() && "Instr doesn't have a FrameIndex Operand");
}
// In order to work out the base and offset for addressing, the FrameLowering
// code needs to know (sometimes) whether the instruction is storing/loading a
// callee-saved register, or whether it's a more generic
// operation. Fortunately the frame indices are used *only* for that purpose
// and are contiguous, so we can check here.
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
int MinCSFI = 0;
int MaxCSFI = -1;
if (CSI.size()) {
MinCSFI = CSI[0].getFrameIdx();
MaxCSFI = CSI[CSI.size() - 1].getFrameIdx();
}
int FrameIndex = MI.getOperand(i).getIndex();
bool IsCalleeSaveOp = FrameIndex >= MinCSFI && FrameIndex <= MaxCSFI;
unsigned FrameReg;
int64_t Offset;
Offset = TFI->resolveFrameIndexReference(MF, FrameIndex, FrameReg, SPAdj,
IsCalleeSaveOp);
Offset += MI.getOperand(i+1).getImm();
// DBG_VALUE instructions have no real restrictions so they can be handled
// easily.
if (MI.isDebugValue()) {
MI.getOperand(i).ChangeToRegister(FrameReg, /*isDef=*/ false);
MI.getOperand(i+1).ChangeToImmediate(Offset);
return;
}
int MinOffset, MaxOffset, OffsetScale;
if (MI.getOpcode() == AArch64::ADDxxi_lsl0_s) {
MinOffset = 0;
MaxOffset = 0xfff;
OffsetScale = 1;
} else {
// Load/store of a stack object
TII.getAddressConstraints(MI, OffsetScale, MinOffset, MaxOffset);
}
// The frame lowering has told us a base and offset it thinks we should use to
// access this variable, but it's still up to us to make sure the values are
// legal for the instruction in question.
if (Offset % OffsetScale != 0 || Offset < MinOffset || Offset > MaxOffset) {
unsigned BaseReg =
MF.getRegInfo().createVirtualRegister(&AArch64::GPR64RegClass);
emitRegUpdate(MBB, MBBI, MBBI->getDebugLoc(), TII,
BaseReg, FrameReg, BaseReg, Offset);
FrameReg = BaseReg;
Offset = 0;
}
// Negative offsets are expected if we address from FP, but for
// now this checks nothing has gone horribly wrong.
assert(Offset >= 0 && "Unexpected negative offset from SP");
MI.getOperand(i).ChangeToRegister(FrameReg, false, false, true);
MI.getOperand(i+1).ChangeToImmediate(Offset / OffsetScale);
}
void
AArch64RegisterInfo::eliminateCallFramePseudoInstr(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
DebugLoc dl = MI->getDebugLoc();
int Opcode = MI->getOpcode();
bool IsDestroy = Opcode == TII.getCallFrameDestroyOpcode();
uint64_t CalleePopAmount = IsDestroy ? MI->getOperand(1).getImm() : 0;
if (!TFI->hasReservedCallFrame(MF)) {
unsigned Align = TFI->getStackAlignment();
uint64_t Amount = MI->getOperand(0).getImm();
Amount = (Amount + Align - 1)/Align * Align;
if (!IsDestroy) Amount = -Amount;
// N.b. if CalleePopAmount is valid but zero (i.e. callee would pop, but it
// doesn't have to pop anything), then the first operand will be zero too so
// this adjustment is a no-op.
if (CalleePopAmount == 0) {
// FIXME: in-function stack adjustment for calls is limited to 12-bits
// because there's no guaranteed temporary register available. Mostly call
// frames will be allocated at the start of a function so this is OK, but
// it is a limitation that needs dealing with.
assert(abs(Amount) < 0xfff && "call frame too large");
emitSPUpdate(MBB, MI, dl, TII, AArch64::NoRegister, Amount);
}
} else if (CalleePopAmount != 0) {
// If the calling convention demands that the callee pops arguments from the
// stack, we want to add it back if we have a reserved call frame.
assert(CalleePopAmount < 0xfff && "call frame too large");
emitSPUpdate(MBB, MI, dl, TII, AArch64::NoRegister, -CalleePopAmount);
}
MBB.erase(MI);
}
unsigned
AArch64RegisterInfo::getFrameRegister(const MachineFunction &MF) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
if (TFI->hasFP(MF))
return AArch64::X29;
else
return AArch64::XSP;
}
bool
AArch64RegisterInfo::useFPForScavengingIndex(const MachineFunction &MF) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
const AArch64FrameLowering *AFI = static_cast<const AArch64FrameLowering*>(TFI);
return AFI->useFPForAddressing(MF);
}
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