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clang-p2996/llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
Diogo Sampaio d94d079a6a [ARM][Thumb2] Fix ADD/SUB invalid writes to SP 
Summary:
This patch fixes pr23772  [ARM] r226200 can emit illegal thumb2 instruction: "sub sp, r12, #80".
The violation was that SUB and ADD (reg, immediate) instructions can only write to SP if the source register is also SP. So the above instructions was unpredictable.
To enforce that the instruction t2(ADD|SUB)ri does not write to SP we now enforce the destination register to be rGPR (That exclude PC and SP).
Different than the ARM specification, that defines one instruction that can read from SP, and one that can't, here we inserted one that can't write to SP, and other that can only write to SP as to reuse most of the hard-coded size optimizations.
When performing this change, it uncovered that emitting Thumb2 Reg plus Immediate could not emit all variants of ADD SP, SP #imm instructions before so it was refactored to be able to. (see test/CodeGen/Thumb2/mve-stacksplot.mir where we use a subw sp, sp, Imm12 variant )
It also uncovered a disassembly issue of adr.w instructions, that were only written as SUBW instructions (see llvm/test/MC/Disassembler/ARM/thumb2.txt).

Reviewers: eli.friedman, dmgreen, carwil, olista01, efriedma, andreadb

Reviewed By: efriedma

Subscribers: gbedwell, john.brawn, efriedma, ostannard, kristof.beyls, hiraditya, dmgreen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70680
2020-01-14 11:47:19 +00:00

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//===- Thumb2InstrInfo.cpp - Thumb-2 Instruction Information --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains the Thumb-2 implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "Thumb2InstrInfo.h"
#include "ARMMachineFunctionInfo.h"
#include "MCTargetDesc/ARMAddressingModes.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetMachine.h"
#include <cassert>
using namespace llvm;
static cl::opt<bool>
OldT2IfCvt("old-thumb2-ifcvt", cl::Hidden,
cl::desc("Use old-style Thumb2 if-conversion heuristics"),
cl::init(false));
Thumb2InstrInfo::Thumb2InstrInfo(const ARMSubtarget &STI)
: ARMBaseInstrInfo(STI) {}
/// Return the noop instruction to use for a noop.
void Thumb2InstrInfo::getNoop(MCInst &NopInst) const {
NopInst.setOpcode(ARM::tHINT);
NopInst.addOperand(MCOperand::createImm(0));
NopInst.addOperand(MCOperand::createImm(ARMCC::AL));
NopInst.addOperand(MCOperand::createReg(0));
}
unsigned Thumb2InstrInfo::getUnindexedOpcode(unsigned Opc) const {
// FIXME
return 0;
}
void
Thumb2InstrInfo::ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,
MachineBasicBlock *NewDest) const {
MachineBasicBlock *MBB = Tail->getParent();
ARMFunctionInfo *AFI = MBB->getParent()->getInfo<ARMFunctionInfo>();
if (!AFI->hasITBlocks() || Tail->isBranch()) {
TargetInstrInfo::ReplaceTailWithBranchTo(Tail, NewDest);
return;
}
// If the first instruction of Tail is predicated, we may have to update
// the IT instruction.
unsigned PredReg = 0;
ARMCC::CondCodes CC = getInstrPredicate(*Tail, PredReg);
MachineBasicBlock::iterator MBBI = Tail;
if (CC != ARMCC::AL)
// Expecting at least the t2IT instruction before it.
--MBBI;
// Actually replace the tail.
TargetInstrInfo::ReplaceTailWithBranchTo(Tail, NewDest);
// Fix up IT.
if (CC != ARMCC::AL) {
MachineBasicBlock::iterator E = MBB->begin();
unsigned Count = 4; // At most 4 instructions in an IT block.
while (Count && MBBI != E) {
if (MBBI->isDebugInstr()) {
--MBBI;
continue;
}
if (MBBI->getOpcode() == ARM::t2IT) {
unsigned Mask = MBBI->getOperand(1).getImm();
if (Count == 4)
MBBI->eraseFromParent();
else {
unsigned MaskOn = 1 << Count;
unsigned MaskOff = ~(MaskOn - 1);
MBBI->getOperand(1).setImm((Mask & MaskOff) | MaskOn);
}
return;
}
--MBBI;
--Count;
}
// Ctrl flow can reach here if branch folding is run before IT block
// formation pass.
}
}
bool
Thumb2InstrInfo::isLegalToSplitMBBAt(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI) const {
while (MBBI->isDebugInstr()) {
++MBBI;
if (MBBI == MBB.end())
return false;
}
unsigned PredReg = 0;
return getITInstrPredicate(*MBBI, PredReg) == ARMCC::AL;
}
void Thumb2InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
const DebugLoc &DL, MCRegister DestReg,
MCRegister SrcReg, bool KillSrc) const {
// Handle SPR, DPR, and QPR copies.
if (!ARM::GPRRegClass.contains(DestReg, SrcReg))
return ARMBaseInstrInfo::copyPhysReg(MBB, I, DL, DestReg, SrcReg, KillSrc);
BuildMI(MBB, I, DL, get(ARM::tMOVr), DestReg)
.addReg(SrcReg, getKillRegState(KillSrc))
.add(predOps(ARMCC::AL));
}
void Thumb2InstrInfo::
storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
unsigned SrcReg, bool isKill, int FI,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
DebugLoc DL;
if (I != MBB.end()) DL = I->getDebugLoc();
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = MF.getFrameInfo();
MachineMemOperand *MMO = MF.getMachineMemOperand(
MachinePointerInfo::getFixedStack(MF, FI), MachineMemOperand::MOStore,
MFI.getObjectSize(FI), MFI.getObjectAlignment(FI));
if (ARM::GPRRegClass.hasSubClassEq(RC)) {
BuildMI(MBB, I, DL, get(ARM::t2STRi12))
.addReg(SrcReg, getKillRegState(isKill))
.addFrameIndex(FI)
.addImm(0)
.addMemOperand(MMO)
.add(predOps(ARMCC::AL));
return;
}
if (ARM::GPRPairRegClass.hasSubClassEq(RC)) {
// Thumb2 STRD expects its dest-registers to be in rGPR. Not a problem for
// gsub_0, but needs an extra constraint for gsub_1 (which could be sp
// otherwise).
if (Register::isVirtualRegister(SrcReg)) {
MachineRegisterInfo *MRI = &MF.getRegInfo();
MRI->constrainRegClass(SrcReg, &ARM::GPRPairnospRegClass);
}
MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(ARM::t2STRDi8));
AddDReg(MIB, SrcReg, ARM::gsub_0, getKillRegState(isKill), TRI);
AddDReg(MIB, SrcReg, ARM::gsub_1, 0, TRI);
MIB.addFrameIndex(FI).addImm(0).addMemOperand(MMO).add(predOps(ARMCC::AL));
return;
}
ARMBaseInstrInfo::storeRegToStackSlot(MBB, I, SrcReg, isKill, FI, RC, TRI);
}
void Thumb2InstrInfo::
loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
unsigned DestReg, int FI,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = MF.getFrameInfo();
MachineMemOperand *MMO = MF.getMachineMemOperand(
MachinePointerInfo::getFixedStack(MF, FI), MachineMemOperand::MOLoad,
MFI.getObjectSize(FI), MFI.getObjectAlignment(FI));
DebugLoc DL;
if (I != MBB.end()) DL = I->getDebugLoc();
if (ARM::GPRRegClass.hasSubClassEq(RC)) {
BuildMI(MBB, I, DL, get(ARM::t2LDRi12), DestReg)
.addFrameIndex(FI)
.addImm(0)
.addMemOperand(MMO)
.add(predOps(ARMCC::AL));
return;
}
if (ARM::GPRPairRegClass.hasSubClassEq(RC)) {
// Thumb2 LDRD expects its dest-registers to be in rGPR. Not a problem for
// gsub_0, but needs an extra constraint for gsub_1 (which could be sp
// otherwise).
if (Register::isVirtualRegister(DestReg)) {
MachineRegisterInfo *MRI = &MF.getRegInfo();
MRI->constrainRegClass(DestReg, &ARM::GPRPairnospRegClass);
}
MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(ARM::t2LDRDi8));
AddDReg(MIB, DestReg, ARM::gsub_0, RegState::DefineNoRead, TRI);
AddDReg(MIB, DestReg, ARM::gsub_1, RegState::DefineNoRead, TRI);
MIB.addFrameIndex(FI).addImm(0).addMemOperand(MMO).add(predOps(ARMCC::AL));
if (Register::isPhysicalRegister(DestReg))
MIB.addReg(DestReg, RegState::ImplicitDefine);
return;
}
ARMBaseInstrInfo::loadRegFromStackSlot(MBB, I, DestReg, FI, RC, TRI);
}
void Thumb2InstrInfo::expandLoadStackGuard(
MachineBasicBlock::iterator MI) const {
MachineFunction &MF = *MI->getParent()->getParent();
if (MF.getTarget().isPositionIndependent())
expandLoadStackGuardBase(MI, ARM::t2MOV_ga_pcrel, ARM::t2LDRi12);
else
expandLoadStackGuardBase(MI, ARM::t2MOVi32imm, ARM::t2LDRi12);
}
void llvm::emitT2RegPlusImmediate(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
const DebugLoc &dl, unsigned DestReg,
unsigned BaseReg, int NumBytes,
ARMCC::CondCodes Pred, unsigned PredReg,
const ARMBaseInstrInfo &TII,
unsigned MIFlags) {
if (NumBytes == 0 && DestReg != BaseReg) {
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
.addReg(BaseReg, RegState::Kill)
.addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
return;
}
bool isSub = NumBytes < 0;
if (isSub) NumBytes = -NumBytes;
// If profitable, use a movw or movt to materialize the offset.
// FIXME: Use the scavenger to grab a scratch register.
if (DestReg != ARM::SP && DestReg != BaseReg &&
NumBytes >= 4096 &&
ARM_AM::getT2SOImmVal(NumBytes) == -1) {
bool Fits = false;
if (NumBytes < 65536) {
// Use a movw to materialize the 16-bit constant.
BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVi16), DestReg)
.addImm(NumBytes)
.addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
Fits = true;
} else if ((NumBytes & 0xffff) == 0) {
// Use a movt to materialize the 32-bit constant.
BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVTi16), DestReg)
.addReg(DestReg)
.addImm(NumBytes >> 16)
.addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
Fits = true;
}
if (Fits) {
if (isSub) {
BuildMI(MBB, MBBI, dl, TII.get(ARM::t2SUBrr), DestReg)
.addReg(BaseReg)
.addReg(DestReg, RegState::Kill)
.add(predOps(Pred, PredReg))
.add(condCodeOp())
.setMIFlags(MIFlags);
} else {
// Here we know that DestReg is not SP but we do not
// know anything about BaseReg. t2ADDrr is an invalid
// instruction is SP is used as the second argument, but
// is fine if SP is the first argument. To be sure we
// do not generate invalid encoding, put BaseReg first.
BuildMI(MBB, MBBI, dl, TII.get(ARM::t2ADDrr), DestReg)
.addReg(BaseReg)
.addReg(DestReg, RegState::Kill)
.add(predOps(Pred, PredReg))
.add(condCodeOp())
.setMIFlags(MIFlags);
}
return;
}
}
while (NumBytes) {
unsigned ThisVal = NumBytes;
unsigned Opc = 0;
if (DestReg == ARM::SP && BaseReg != ARM::SP) {
// mov sp, rn. Note t2MOVr cannot be used.
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
.addReg(BaseReg)
.setMIFlags(MIFlags)
.add(predOps(ARMCC::AL));
BaseReg = ARM::SP;
continue;
}
assert((DestReg != ARM::SP || BaseReg == ARM::SP) &&
"Writing to SP, from other register.");
// Try to use T1, as it smaller
if ((DestReg == ARM::SP) && (ThisVal < ((1 << 7) - 1) * 4)) {
assert((ThisVal & 3) == 0 && "Stack update is not multiple of 4?");
Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
.addReg(BaseReg)
.addImm(ThisVal / 4)
.setMIFlags(MIFlags)
.add(predOps(ARMCC::AL));
break;
}
bool HasCCOut = true;
int ImmIsT2SO = ARM_AM::getT2SOImmVal(ThisVal);
bool ToSP = DestReg == ARM::SP;
unsigned t2SUB = ToSP ? ARM::t2SUBspImm : ARM::t2SUBri;
unsigned t2ADD = ToSP ? ARM::t2ADDspImm : ARM::t2ADDri;
unsigned t2SUBi12 = ToSP ? ARM::t2SUBspImm12 : ARM::t2SUBri12;
unsigned t2ADDi12 = ToSP ? ARM::t2ADDspImm12 : ARM::t2ADDri12;
Opc = isSub ? t2SUB : t2ADD;
// Prefer T2: sub rd, rn, so_imm | sub sp, sp, so_imm
if (ImmIsT2SO != -1) {
NumBytes = 0;
} else if (ThisVal < 4096) {
// Prefer T3 if can make it in a single go: subw rd, rn, imm12 | subw sp,
// sp, imm12
Opc = isSub ? t2SUBi12 : t2ADDi12;
HasCCOut = false;
NumBytes = 0;
} else {
// Use one T2 instruction to reduce NumBytes
// FIXME: Move this to ARMAddressingModes.h?
unsigned RotAmt = countLeadingZeros(ThisVal);
ThisVal = ThisVal & ARM_AM::rotr32(0xff000000U, RotAmt);
NumBytes &= ~ThisVal;
assert(ARM_AM::getT2SOImmVal(ThisVal) != -1 &&
"Bit extraction didn't work?");
}
// Build the new ADD / SUB.
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
.addReg(BaseReg, RegState::Kill)
.addImm(ThisVal)
.add(predOps(ARMCC::AL))
.setMIFlags(MIFlags);
if (HasCCOut)
MIB.add(condCodeOp());
BaseReg = DestReg;
}
}
static unsigned
negativeOffsetOpcode(unsigned opcode)
{
switch (opcode) {
case ARM::t2LDRi12: return ARM::t2LDRi8;
case ARM::t2LDRHi12: return ARM::t2LDRHi8;
case ARM::t2LDRBi12: return ARM::t2LDRBi8;
case ARM::t2LDRSHi12: return ARM::t2LDRSHi8;
case ARM::t2LDRSBi12: return ARM::t2LDRSBi8;
case ARM::t2STRi12: return ARM::t2STRi8;
case ARM::t2STRBi12: return ARM::t2STRBi8;
case ARM::t2STRHi12: return ARM::t2STRHi8;
case ARM::t2PLDi12: return ARM::t2PLDi8;
case ARM::t2PLDWi12: return ARM::t2PLDWi8;
case ARM::t2PLIi12: return ARM::t2PLIi8;
case ARM::t2LDRi8:
case ARM::t2LDRHi8:
case ARM::t2LDRBi8:
case ARM::t2LDRSHi8:
case ARM::t2LDRSBi8:
case ARM::t2STRi8:
case ARM::t2STRBi8:
case ARM::t2STRHi8:
case ARM::t2PLDi8:
case ARM::t2PLDWi8:
case ARM::t2PLIi8:
return opcode;
default:
llvm_unreachable("unknown thumb2 opcode.");
}
}
static unsigned
positiveOffsetOpcode(unsigned opcode)
{
switch (opcode) {
case ARM::t2LDRi8: return ARM::t2LDRi12;
case ARM::t2LDRHi8: return ARM::t2LDRHi12;
case ARM::t2LDRBi8: return ARM::t2LDRBi12;
case ARM::t2LDRSHi8: return ARM::t2LDRSHi12;
case ARM::t2LDRSBi8: return ARM::t2LDRSBi12;
case ARM::t2STRi8: return ARM::t2STRi12;
case ARM::t2STRBi8: return ARM::t2STRBi12;
case ARM::t2STRHi8: return ARM::t2STRHi12;
case ARM::t2PLDi8: return ARM::t2PLDi12;
case ARM::t2PLDWi8: return ARM::t2PLDWi12;
case ARM::t2PLIi8: return ARM::t2PLIi12;
case ARM::t2LDRi12:
case ARM::t2LDRHi12:
case ARM::t2LDRBi12:
case ARM::t2LDRSHi12:
case ARM::t2LDRSBi12:
case ARM::t2STRi12:
case ARM::t2STRBi12:
case ARM::t2STRHi12:
case ARM::t2PLDi12:
case ARM::t2PLDWi12:
case ARM::t2PLIi12:
return opcode;
default:
llvm_unreachable("unknown thumb2 opcode.");
}
}
static unsigned
immediateOffsetOpcode(unsigned opcode)
{
switch (opcode) {
case ARM::t2LDRs: return ARM::t2LDRi12;
case ARM::t2LDRHs: return ARM::t2LDRHi12;
case ARM::t2LDRBs: return ARM::t2LDRBi12;
case ARM::t2LDRSHs: return ARM::t2LDRSHi12;
case ARM::t2LDRSBs: return ARM::t2LDRSBi12;
case ARM::t2STRs: return ARM::t2STRi12;
case ARM::t2STRBs: return ARM::t2STRBi12;
case ARM::t2STRHs: return ARM::t2STRHi12;
case ARM::t2PLDs: return ARM::t2PLDi12;
case ARM::t2PLDWs: return ARM::t2PLDWi12;
case ARM::t2PLIs: return ARM::t2PLIi12;
case ARM::t2LDRi12:
case ARM::t2LDRHi12:
case ARM::t2LDRBi12:
case ARM::t2LDRSHi12:
case ARM::t2LDRSBi12:
case ARM::t2STRi12:
case ARM::t2STRBi12:
case ARM::t2STRHi12:
case ARM::t2PLDi12:
case ARM::t2PLDWi12:
case ARM::t2PLIi12:
case ARM::t2LDRi8:
case ARM::t2LDRHi8:
case ARM::t2LDRBi8:
case ARM::t2LDRSHi8:
case ARM::t2LDRSBi8:
case ARM::t2STRi8:
case ARM::t2STRBi8:
case ARM::t2STRHi8:
case ARM::t2PLDi8:
case ARM::t2PLDWi8:
case ARM::t2PLIi8:
return opcode;
default:
llvm_unreachable("unknown thumb2 opcode.");
}
}
bool llvm::rewriteT2FrameIndex(MachineInstr &MI, unsigned FrameRegIdx,
unsigned FrameReg, int &Offset,
const ARMBaseInstrInfo &TII,
const TargetRegisterInfo *TRI) {
unsigned Opcode = MI.getOpcode();
const MCInstrDesc &Desc = MI.getDesc();
unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
bool isSub = false;
MachineFunction &MF = *MI.getParent()->getParent();
const TargetRegisterClass *RegClass =
TII.getRegClass(Desc, FrameRegIdx, TRI, MF);
// Memory operands in inline assembly always use AddrModeT2_i12.
if (Opcode == ARM::INLINEASM || Opcode == ARM::INLINEASM_BR)
AddrMode = ARMII::AddrModeT2_i12; // FIXME. mode for thumb2?
const bool IsSP = Opcode == ARM::t2ADDspImm12 || Opcode == ARM::t2ADDspImm;
if (IsSP || Opcode == ARM::t2ADDri || Opcode == ARM::t2ADDri12) {
Offset += MI.getOperand(FrameRegIdx+1).getImm();
unsigned PredReg;
if (Offset == 0 && getInstrPredicate(MI, PredReg) == ARMCC::AL &&
!MI.definesRegister(ARM::CPSR)) {
// Turn it into a move.
MI.setDesc(TII.get(ARM::tMOVr));
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
// Remove offset and remaining explicit predicate operands.
do MI.RemoveOperand(FrameRegIdx+1);
while (MI.getNumOperands() > FrameRegIdx+1);
MachineInstrBuilder MIB(*MI.getParent()->getParent(), &MI);
MIB.add(predOps(ARMCC::AL));
return true;
}
bool HasCCOut = (Opcode != ARM::t2ADDspImm12 && Opcode != ARM::t2ADDri12);
if (Offset < 0) {
Offset = -Offset;
isSub = true;
MI.setDesc(IsSP ? TII.get(ARM::t2SUBspImm) : TII.get(ARM::t2SUBri));
} else {
MI.setDesc(IsSP ? TII.get(ARM::t2ADDspImm) : TII.get(ARM::t2ADDri));
}
// Common case: small offset, fits into instruction.
if (ARM_AM::getT2SOImmVal(Offset) != -1) {
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
// Add cc_out operand if the original instruction did not have one.
if (!HasCCOut)
MI.addOperand(MachineOperand::CreateReg(0, false));
Offset = 0;
return true;
}
// Another common case: imm12.
if (Offset < 4096 &&
(!HasCCOut || MI.getOperand(MI.getNumOperands()-1).getReg() == 0)) {
unsigned NewOpc = isSub ? IsSP ? ARM::t2SUBspImm12 : ARM::t2SUBri12
: IsSP ? ARM::t2ADDspImm12 : ARM::t2ADDri12;
MI.setDesc(TII.get(NewOpc));
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
// Remove the cc_out operand.
if (HasCCOut)
MI.RemoveOperand(MI.getNumOperands()-1);
Offset = 0;
return true;
}
// Otherwise, extract 8 adjacent bits from the immediate into this
// t2ADDri/t2SUBri.
unsigned RotAmt = countLeadingZeros<unsigned>(Offset);
unsigned ThisImmVal = Offset & ARM_AM::rotr32(0xff000000U, RotAmt);
// We will handle these bits from offset, clear them.
Offset &= ~ThisImmVal;
assert(ARM_AM::getT2SOImmVal(ThisImmVal) != -1 &&
"Bit extraction didn't work?");
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(ThisImmVal);
// Add cc_out operand if the original instruction did not have one.
if (!HasCCOut)
MI.addOperand(MachineOperand::CreateReg(0, false));
} else {
// AddrMode4 and AddrMode6 cannot handle any offset.
if (AddrMode == ARMII::AddrMode4 || AddrMode == ARMII::AddrMode6)
return false;
// AddrModeT2_so cannot handle any offset. If there is no offset
// register then we change to an immediate version.
unsigned NewOpc = Opcode;
if (AddrMode == ARMII::AddrModeT2_so) {
Register OffsetReg = MI.getOperand(FrameRegIdx + 1).getReg();
if (OffsetReg != 0) {
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
return Offset == 0;
}
MI.RemoveOperand(FrameRegIdx+1);
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(0);
NewOpc = immediateOffsetOpcode(Opcode);
AddrMode = ARMII::AddrModeT2_i12;
}
unsigned NumBits = 0;
unsigned Scale = 1;
if (AddrMode == ARMII::AddrModeT2_i8 || AddrMode == ARMII::AddrModeT2_i12) {
// i8 supports only negative, and i12 supports only positive, so
// based on Offset sign convert Opcode to the appropriate
// instruction
Offset += MI.getOperand(FrameRegIdx+1).getImm();
if (Offset < 0) {
NewOpc = negativeOffsetOpcode(Opcode);
NumBits = 8;
isSub = true;
Offset = -Offset;
} else {
NewOpc = positiveOffsetOpcode(Opcode);
NumBits = 12;
}
} else if (AddrMode == ARMII::AddrMode5) {
// VFP address mode.
const MachineOperand &OffOp = MI.getOperand(FrameRegIdx+1);
int InstrOffs = ARM_AM::getAM5Offset(OffOp.getImm());
if (ARM_AM::getAM5Op(OffOp.getImm()) == ARM_AM::sub)
InstrOffs *= -1;
NumBits = 8;
Scale = 4;
Offset += InstrOffs * 4;
assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
if (Offset < 0) {
Offset = -Offset;
isSub = true;
}
} else if (AddrMode == ARMII::AddrMode5FP16) {
// VFP address mode.
const MachineOperand &OffOp = MI.getOperand(FrameRegIdx+1);
int InstrOffs = ARM_AM::getAM5FP16Offset(OffOp.getImm());
if (ARM_AM::getAM5FP16Op(OffOp.getImm()) == ARM_AM::sub)
InstrOffs *= -1;
NumBits = 8;
Scale = 2;
Offset += InstrOffs * 2;
assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
if (Offset < 0) {
Offset = -Offset;
isSub = true;
}
} else if (AddrMode == ARMII::AddrModeT2_i7s4 ||
AddrMode == ARMII::AddrModeT2_i7s2 ||
AddrMode == ARMII::AddrModeT2_i7) {
Offset += MI.getOperand(FrameRegIdx + 1).getImm();
unsigned OffsetMask;
switch (AddrMode) {
case ARMII::AddrModeT2_i7s4: NumBits = 9; OffsetMask = 0x3; break;
case ARMII::AddrModeT2_i7s2: NumBits = 8; OffsetMask = 0x1; break;
default: NumBits = 7; OffsetMask = 0x0; break;
}
// MCInst operand expects already scaled value.
Scale = 1;
assert((Offset & OffsetMask) == 0 && "Can't encode this offset!");
(void)OffsetMask; // squash unused-variable warning at -NDEBUG
} else if (AddrMode == ARMII::AddrModeT2_i8s4) {
Offset += MI.getOperand(FrameRegIdx + 1).getImm() * 4;
NumBits = 8 + 2;
// MCInst operand expects already scaled value.
Scale = 1;
assert((Offset & 3) == 0 && "Can't encode this offset!");
} else if (AddrMode == ARMII::AddrModeT2_ldrex) {
Offset += MI.getOperand(FrameRegIdx + 1).getImm() * 4;
NumBits = 8; // 8 bits scaled by 4
Scale = 4;
assert((Offset & 3) == 0 && "Can't encode this offset!");
} else {
llvm_unreachable("Unsupported addressing mode!");
}
if (NewOpc != Opcode)
MI.setDesc(TII.get(NewOpc));
MachineOperand &ImmOp = MI.getOperand(FrameRegIdx+1);
// Attempt to fold address computation
// Common case: small offset, fits into instruction. We need to make sure
// the register class is correct too, for instructions like the MVE
// VLDRH.32, which only accepts low tGPR registers.
int ImmedOffset = Offset / Scale;
unsigned Mask = (1 << NumBits) - 1;
if ((unsigned)Offset <= Mask * Scale &&
(Register::isVirtualRegister(FrameReg) ||
RegClass->contains(FrameReg))) {
if (Register::isVirtualRegister(FrameReg)) {
// Make sure the register class for the virtual register is correct
MachineRegisterInfo *MRI = &MF.getRegInfo();
if (!MRI->constrainRegClass(FrameReg, RegClass))
llvm_unreachable("Unable to constrain virtual register class.");
}
// Replace the FrameIndex with fp/sp
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
if (isSub) {
if (AddrMode == ARMII::AddrMode5 || AddrMode == ARMII::AddrMode5FP16)
// FIXME: Not consistent.
ImmedOffset |= 1 << NumBits;
else
ImmedOffset = -ImmedOffset;
}
ImmOp.ChangeToImmediate(ImmedOffset);
Offset = 0;
return true;
}
// Otherwise, offset doesn't fit. Pull in what we can to simplify
ImmedOffset = ImmedOffset & Mask;
if (isSub) {
if (AddrMode == ARMII::AddrMode5 || AddrMode == ARMII::AddrMode5FP16)
// FIXME: Not consistent.
ImmedOffset |= 1 << NumBits;
else {
ImmedOffset = -ImmedOffset;
if (ImmedOffset == 0)
// Change the opcode back if the encoded offset is zero.
MI.setDesc(TII.get(positiveOffsetOpcode(NewOpc)));
}
}
ImmOp.ChangeToImmediate(ImmedOffset);
Offset &= ~(Mask*Scale);
}
Offset = (isSub) ? -Offset : Offset;
return Offset == 0 && (Register::isVirtualRegister(FrameReg) ||
RegClass->contains(FrameReg));
}
ARMCC::CondCodes llvm::getITInstrPredicate(const MachineInstr &MI,
unsigned &PredReg) {
unsigned Opc = MI.getOpcode();
if (Opc == ARM::tBcc || Opc == ARM::t2Bcc)
return ARMCC::AL;
return getInstrPredicate(MI, PredReg);
}
int llvm::findFirstVPTPredOperandIdx(const MachineInstr &MI) {
const MCInstrDesc &MCID = MI.getDesc();
if (!MCID.OpInfo)
return -1;
for (unsigned i = 0, e = MCID.getNumOperands(); i != e; ++i)
if (ARM::isVpred(MCID.OpInfo[i].OperandType))
return i;
return -1;
}
ARMVCC::VPTCodes llvm::getVPTInstrPredicate(const MachineInstr &MI,
unsigned &PredReg) {
int PIdx = findFirstVPTPredOperandIdx(MI);
if (PIdx == -1) {
PredReg = 0;
return ARMVCC::None;
}
PredReg = MI.getOperand(PIdx+1).getReg();
return (ARMVCC::VPTCodes)MI.getOperand(PIdx).getImm();
}
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