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llvm-6502/lib/Target/ARM/Thumb2SizeReduction.cpp
Jim Grosbach 4152778605 Radar 7417921 
tMOVCCi pattern only valid for low registers, as the Thumb1 mov immediate to
register instruction only works with low registers. Allowing high registers
for the instruction resulted in the assembler choosing the wide (32-bit)
encoding for the mov, but LLVM though the instruction was only 16 bits wide,
so offset calculations for constant pools became incorrect, leading to
out of range constant pool entries.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95686 91177308-0d34-0410-b5e6-96231b3b80d8
2010-02-09 19:51:37 +00:00

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25 KiB
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//===-- Thumb2SizeReduction.cpp - Thumb2 code size reduction pass -*- C++ -*-=//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "t2-reduce-size"
#include "ARM.h"
#include "ARMAddressingModes.h"
#include "ARMBaseRegisterInfo.h"
#include "ARMBaseInstrInfo.h"
#include "Thumb2InstrInfo.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
STATISTIC(NumNarrows, "Number of 32-bit instrs reduced to 16-bit ones");
STATISTIC(Num2Addrs, "Number of 32-bit instrs reduced to 2addr 16-bit ones");
STATISTIC(NumLdSts, "Number of 32-bit load / store reduced to 16-bit ones");
static cl::opt<int> ReduceLimit("t2-reduce-limit",
cl::init(-1), cl::Hidden);
static cl::opt<int> ReduceLimit2Addr("t2-reduce-limit2",
cl::init(-1), cl::Hidden);
static cl::opt<int> ReduceLimitLdSt("t2-reduce-limit3",
cl::init(-1), cl::Hidden);
namespace {
/// ReduceTable - A static table with information on mapping from wide
/// opcodes to narrow
struct ReduceEntry {
unsigned WideOpc; // Wide opcode
unsigned NarrowOpc1; // Narrow opcode to transform to
unsigned NarrowOpc2; // Narrow opcode when it's two-address
uint8_t Imm1Limit; // Limit of immediate field (bits)
uint8_t Imm2Limit; // Limit of immediate field when it's two-address
unsigned LowRegs1 : 1; // Only possible if low-registers are used
unsigned LowRegs2 : 1; // Only possible if low-registers are used (2addr)
unsigned PredCC1 : 2; // 0 - If predicated, cc is on and vice versa.
// 1 - No cc field.
// 2 - Always set CPSR.
unsigned PredCC2 : 2;
unsigned Special : 1; // Needs to be dealt with specially
};
static const ReduceEntry ReduceTable[] = {
// Wide, Narrow1, Narrow2, imm1,imm2, lo1, lo2, P/C, S
{ ARM::t2ADCrr, 0, ARM::tADC, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2ADDri, ARM::tADDi3, ARM::tADDi8, 3, 8, 1, 1, 0,0, 0 },
{ ARM::t2ADDrr, ARM::tADDrr, ARM::tADDhirr, 0, 0, 1, 0, 0,1, 0 },
// Note: immediate scale is 4.
{ ARM::t2ADDrSPi,ARM::tADDrSPi,0, 8, 0, 1, 0, 1,0, 0 },
{ ARM::t2ADDSri,ARM::tADDi3, ARM::tADDi8, 3, 8, 1, 1, 2,2, 1 },
{ ARM::t2ADDSrr,ARM::tADDrr, 0, 0, 0, 1, 0, 2,0, 1 },
{ ARM::t2ANDrr, 0, ARM::tAND, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2ASRri, ARM::tASRri, 0, 5, 0, 1, 0, 0,0, 0 },
{ ARM::t2ASRrr, 0, ARM::tASRrr, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2BICrr, 0, ARM::tBIC, 0, 0, 0, 1, 0,0, 0 },
//FIXME: Disable CMN, as CCodes are backwards from compare expectations
//{ ARM::t2CMNrr, ARM::tCMN, 0, 0, 0, 1, 0, 2,0, 0 },
{ ARM::t2CMPri, ARM::tCMPi8, 0, 8, 0, 1, 0, 2,0, 0 },
{ ARM::t2CMPrr, ARM::tCMPhir, 0, 0, 0, 0, 0, 2,0, 0 },
{ ARM::t2CMPzri,ARM::tCMPzi8, 0, 8, 0, 1, 0, 2,0, 0 },
{ ARM::t2CMPzrr,ARM::tCMPzhir,0, 0, 0, 0, 0, 2,0, 0 },
{ ARM::t2EORrr, 0, ARM::tEOR, 0, 0, 0, 1, 0,0, 0 },
// FIXME: adr.n immediate offset must be multiple of 4.
//{ ARM::t2LEApcrelJT,ARM::tLEApcrelJT, 0, 0, 0, 1, 0, 1,0, 0 },
{ ARM::t2LSLri, ARM::tLSLri, 0, 5, 0, 1, 0, 0,0, 0 },
{ ARM::t2LSLrr, 0, ARM::tLSLrr, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2LSRri, ARM::tLSRri, 0, 5, 0, 1, 0, 0,0, 0 },
{ ARM::t2LSRrr, 0, ARM::tLSRrr, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2MOVi, ARM::tMOVi8, 0, 8, 0, 1, 0, 0,0, 0 },
{ ARM::t2MOVi16,ARM::tMOVi8, 0, 8, 0, 1, 0, 0,0, 1 },
// FIXME: Do we need the 16-bit 'S' variant?
{ ARM::t2MOVr,ARM::tMOVgpr2gpr,0, 0, 0, 0, 0, 1,0, 0 },
{ ARM::t2MOVCCr,0, ARM::tMOVCCr, 0, 0, 0, 0, 0,1, 0 },
{ ARM::t2MOVCCi,0, ARM::tMOVCCi, 0, 8, 0, 1, 0,1, 0 },
{ ARM::t2MUL, 0, ARM::tMUL, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2MVNr, ARM::tMVN, 0, 0, 0, 1, 0, 0,0, 0 },
{ ARM::t2ORRrr, 0, ARM::tORR, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2REV, ARM::tREV, 0, 0, 0, 1, 0, 1,0, 0 },
{ ARM::t2REV16, ARM::tREV16, 0, 0, 0, 1, 0, 1,0, 0 },
{ ARM::t2REVSH, ARM::tREVSH, 0, 0, 0, 1, 0, 1,0, 0 },
{ ARM::t2RORrr, 0, ARM::tROR, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2RSBri, ARM::tRSB, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2RSBSri,ARM::tRSB, 0, 0, 0, 1, 0, 2,0, 1 },
{ ARM::t2SBCrr, 0, ARM::tSBC, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2SUBri, ARM::tSUBi3, ARM::tSUBi8, 3, 8, 1, 1, 0,0, 0 },
{ ARM::t2SUBrr, ARM::tSUBrr, 0, 0, 0, 1, 0, 0,0, 0 },
{ ARM::t2SUBSri,ARM::tSUBi3, ARM::tSUBi8, 3, 8, 1, 1, 2,2, 0 },
{ ARM::t2SUBSrr,ARM::tSUBrr, 0, 0, 0, 1, 0, 2,0, 0 },
{ ARM::t2SXTBr, ARM::tSXTB, 0, 0, 0, 1, 0, 1,0, 0 },
{ ARM::t2SXTHr, ARM::tSXTH, 0, 0, 0, 1, 0, 1,0, 0 },
{ ARM::t2TSTrr, ARM::tTST, 0, 0, 0, 1, 0, 2,0, 0 },
{ ARM::t2UXTBr, ARM::tUXTB, 0, 0, 0, 1, 0, 1,0, 0 },
{ ARM::t2UXTHr, ARM::tUXTH, 0, 0, 0, 1, 0, 1,0, 0 },
// FIXME: Clean this up after splitting each Thumb load / store opcode
// into multiple ones.
{ ARM::t2LDRi12,ARM::tLDR, ARM::tLDRspi, 5, 8, 1, 0, 0,0, 1 },
{ ARM::t2LDRs, ARM::tLDR, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2LDRBi12,ARM::tLDRB, 0, 5, 0, 1, 0, 0,0, 1 },
{ ARM::t2LDRBs, ARM::tLDRB, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2LDRHi12,ARM::tLDRH, 0, 5, 0, 1, 0, 0,0, 1 },
{ ARM::t2LDRHs, ARM::tLDRH, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2LDRSBs,ARM::tLDRSB, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2LDRSHs,ARM::tLDRSH, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2STRi12,ARM::tSTR, ARM::tSTRspi, 5, 8, 1, 0, 0,0, 1 },
{ ARM::t2STRs, ARM::tSTR, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2STRBi12,ARM::tSTRB, 0, 5, 0, 1, 0, 0,0, 1 },
{ ARM::t2STRBs, ARM::tSTRB, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2STRHi12,ARM::tSTRH, 0, 5, 0, 1, 0, 0,0, 1 },
{ ARM::t2STRHs, ARM::tSTRH, 0, 0, 0, 1, 0, 0,0, 1 },
{ ARM::t2LDM_RET,0, ARM::tPOP_RET, 0, 0, 1, 1, 1,1, 1 },
{ ARM::t2LDM, ARM::tLDM, ARM::tPOP, 0, 0, 1, 1, 1,1, 1 },
{ ARM::t2STM, ARM::tSTM, ARM::tPUSH, 0, 0, 1, 1, 1,1, 1 },
};
class Thumb2SizeReduce : public MachineFunctionPass {
public:
static char ID;
Thumb2SizeReduce();
const Thumb2InstrInfo *TII;
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual const char *getPassName() const {
return "Thumb2 instruction size reduction pass";
}
private:
/// ReduceOpcodeMap - Maps wide opcode to index of entry in ReduceTable.
DenseMap<unsigned, unsigned> ReduceOpcodeMap;
bool VerifyPredAndCC(MachineInstr *MI, const ReduceEntry &Entry,
bool is2Addr, ARMCC::CondCodes Pred,
bool LiveCPSR, bool &HasCC, bool &CCDead);
bool ReduceLoadStore(MachineBasicBlock &MBB, MachineInstr *MI,
const ReduceEntry &Entry);
bool ReduceSpecial(MachineBasicBlock &MBB, MachineInstr *MI,
const ReduceEntry &Entry, bool LiveCPSR);
/// ReduceTo2Addr - Reduce a 32-bit instruction to a 16-bit two-address
/// instruction.
bool ReduceTo2Addr(MachineBasicBlock &MBB, MachineInstr *MI,
const ReduceEntry &Entry,
bool LiveCPSR);
/// ReduceToNarrow - Reduce a 32-bit instruction to a 16-bit
/// non-two-address instruction.
bool ReduceToNarrow(MachineBasicBlock &MBB, MachineInstr *MI,
const ReduceEntry &Entry,
bool LiveCPSR);
/// ReduceMBB - Reduce width of instructions in the specified basic block.
bool ReduceMBB(MachineBasicBlock &MBB);
};
char Thumb2SizeReduce::ID = 0;
}
Thumb2SizeReduce::Thumb2SizeReduce() : MachineFunctionPass(&ID) {
for (unsigned i = 0, e = array_lengthof(ReduceTable); i != e; ++i) {
unsigned FromOpc = ReduceTable[i].WideOpc;
if (!ReduceOpcodeMap.insert(std::make_pair(FromOpc, i)).second)
assert(false && "Duplicated entries?");
}
}
static bool HasImplicitCPSRDef(const TargetInstrDesc &TID) {
for (const unsigned *Regs = TID.ImplicitDefs; *Regs; ++Regs)
if (*Regs == ARM::CPSR)
return true;
return false;
}
bool
Thumb2SizeReduce::VerifyPredAndCC(MachineInstr *MI, const ReduceEntry &Entry,
bool is2Addr, ARMCC::CondCodes Pred,
bool LiveCPSR, bool &HasCC, bool &CCDead) {
if ((is2Addr && Entry.PredCC2 == 0) ||
(!is2Addr && Entry.PredCC1 == 0)) {
if (Pred == ARMCC::AL) {
// Not predicated, must set CPSR.
if (!HasCC) {
// Original instruction was not setting CPSR, but CPSR is not
// currently live anyway. It's ok to set it. The CPSR def is
// dead though.
if (!LiveCPSR) {
HasCC = true;
CCDead = true;
return true;
}
return false;
}
} else {
// Predicated, must not set CPSR.
if (HasCC)
return false;
}
} else if ((is2Addr && Entry.PredCC2 == 2) ||
(!is2Addr && Entry.PredCC1 == 2)) {
/// Old opcode has an optional def of CPSR.
if (HasCC)
return true;
// If both old opcode does not implicit CPSR def, then it's not ok since
// these new opcodes CPSR def is not meant to be thrown away. e.g. CMP.
if (!HasImplicitCPSRDef(MI->getDesc()))
return false;
HasCC = true;
} else {
// 16-bit instruction does not set CPSR.
if (HasCC)
return false;
}
return true;
}
static bool VerifyLowRegs(MachineInstr *MI) {
unsigned Opc = MI->getOpcode();
bool isPCOk = (Opc == ARM::t2LDM_RET) || (Opc == ARM::t2LDM);
bool isLROk = (Opc == ARM::t2STM);
bool isSPOk = isPCOk || isLROk || (Opc == ARM::t2ADDrSPi);
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || MO.isImplicit())
continue;
unsigned Reg = MO.getReg();
if (Reg == 0 || Reg == ARM::CPSR)
continue;
if (isPCOk && Reg == ARM::PC)
continue;
if (isLROk && Reg == ARM::LR)
continue;
if (Reg == ARM::SP) {
if (isSPOk)
continue;
if (i == 1 && (Opc == ARM::t2LDRi12 || Opc == ARM::t2STRi12))
// Special case for these ldr / str with sp as base register.
continue;
}
if (!isARMLowRegister(Reg))
return false;
}
return true;
}
bool
Thumb2SizeReduce::ReduceLoadStore(MachineBasicBlock &MBB, MachineInstr *MI,
const ReduceEntry &Entry) {
if (ReduceLimitLdSt != -1 && ((int)NumLdSts >= ReduceLimitLdSt))
return false;
unsigned Scale = 1;
bool HasImmOffset = false;
bool HasShift = false;
bool HasOffReg = true;
bool isLdStMul = false;
unsigned Opc = Entry.NarrowOpc1;
unsigned OpNum = 3; // First 'rest' of operands.
uint8_t ImmLimit = Entry.Imm1Limit;
switch (Entry.WideOpc) {
default:
llvm_unreachable("Unexpected Thumb2 load / store opcode!");
case ARM::t2LDRi12:
case ARM::t2STRi12: {
unsigned BaseReg = MI->getOperand(1).getReg();
if (BaseReg == ARM::SP) {
Opc = Entry.NarrowOpc2;
ImmLimit = Entry.Imm2Limit;
HasOffReg = false;
}
Scale = 4;
HasImmOffset = true;
break;
}
case ARM::t2LDRBi12:
case ARM::t2STRBi12:
HasImmOffset = true;
break;
case ARM::t2LDRHi12:
case ARM::t2STRHi12:
Scale = 2;
HasImmOffset = true;
break;
case ARM::t2LDRs:
case ARM::t2LDRBs:
case ARM::t2LDRHs:
case ARM::t2LDRSBs:
case ARM::t2LDRSHs:
case ARM::t2STRs:
case ARM::t2STRBs:
case ARM::t2STRHs:
HasShift = true;
OpNum = 4;
break;
case ARM::t2LDM_RET:
case ARM::t2LDM:
case ARM::t2STM: {
OpNum = 0;
unsigned BaseReg = MI->getOperand(0).getReg();
unsigned Mode = MI->getOperand(1).getImm();
if (BaseReg == ARM::SP && ARM_AM::getAM4WBFlag(Mode)) {
Opc = Entry.NarrowOpc2;
OpNum = 2;
} else if (Entry.WideOpc == ARM::t2LDM_RET ||
!isARMLowRegister(BaseReg) ||
!ARM_AM::getAM4WBFlag(Mode) ||
ARM_AM::getAM4SubMode(Mode) != ARM_AM::ia) {
return false;
}
isLdStMul = true;
break;
}
}
unsigned OffsetReg = 0;
bool OffsetKill = false;
if (HasShift) {
OffsetReg = MI->getOperand(2).getReg();
OffsetKill = MI->getOperand(2).isKill();
if (MI->getOperand(3).getImm())
// Thumb1 addressing mode doesn't support shift.
return false;
}
unsigned OffsetImm = 0;
if (HasImmOffset) {
OffsetImm = MI->getOperand(2).getImm();
unsigned MaxOffset = ((1 << ImmLimit) - 1) * Scale;
if ((OffsetImm & (Scale-1)) || OffsetImm > MaxOffset)
// Make sure the immediate field fits.
return false;
}
// Add the 16-bit load / store instruction.
// FIXME: Thumb1 addressing mode encode both immediate and register offset.
DebugLoc dl = MI->getDebugLoc();
MachineInstrBuilder MIB = BuildMI(MBB, *MI, dl, TII->get(Opc));
if (!isLdStMul) {
MIB.addOperand(MI->getOperand(0)).addOperand(MI->getOperand(1));
if (Opc != ARM::tLDRSB && Opc != ARM::tLDRSH) {
// tLDRSB and tLDRSH do not have an immediate offset field. On the other
// hand, it must have an offset register.
// FIXME: Remove this special case.
MIB.addImm(OffsetImm/Scale);
}
assert((!HasShift || OffsetReg) && "Invalid so_reg load / store address!");
if (HasOffReg)
MIB.addReg(OffsetReg, getKillRegState(OffsetKill));
}
// Transfer the rest of operands.
for (unsigned e = MI->getNumOperands(); OpNum != e; ++OpNum)
MIB.addOperand(MI->getOperand(OpNum));
// Transfer memoperands.
(*MIB).setMemRefs(MI->memoperands_begin(), MI->memoperands_end());
DEBUG(errs() << "Converted 32-bit: " << *MI << " to 16-bit: " << *MIB);
MBB.erase(MI);
++NumLdSts;
return true;
}
bool
Thumb2SizeReduce::ReduceSpecial(MachineBasicBlock &MBB, MachineInstr *MI,
const ReduceEntry &Entry,
bool LiveCPSR) {
if (Entry.LowRegs1 && !VerifyLowRegs(MI))
return false;
const TargetInstrDesc &TID = MI->getDesc();
if (TID.mayLoad() || TID.mayStore())
return ReduceLoadStore(MBB, MI, Entry);
unsigned Opc = MI->getOpcode();
switch (Opc) {
default: break;
case ARM::t2ADDSri:
case ARM::t2ADDSrr: {
unsigned PredReg = 0;
if (getInstrPredicate(MI, PredReg) == ARMCC::AL) {
switch (Opc) {
default: break;
case ARM::t2ADDSri: {
if (ReduceTo2Addr(MBB, MI, Entry, LiveCPSR))
return true;
// fallthrough
}
case ARM::t2ADDSrr:
return ReduceToNarrow(MBB, MI, Entry, LiveCPSR);
}
}
break;
}
case ARM::t2RSBri:
case ARM::t2RSBSri:
if (MI->getOperand(2).getImm() == 0)
return ReduceToNarrow(MBB, MI, Entry, LiveCPSR);
break;
case ARM::t2MOVi16:
// Can convert only 'pure' immediate operands, not immediates obtained as
// globals' addresses.
if (MI->getOperand(1).isImm())
return ReduceToNarrow(MBB, MI, Entry, LiveCPSR);
break;
}
return false;
}
bool
Thumb2SizeReduce::ReduceTo2Addr(MachineBasicBlock &MBB, MachineInstr *MI,
const ReduceEntry &Entry,
bool LiveCPSR) {
if (ReduceLimit2Addr != -1 && ((int)Num2Addrs >= ReduceLimit2Addr))
return false;
const TargetInstrDesc &TID = MI->getDesc();
unsigned Reg0 = MI->getOperand(0).getReg();
unsigned Reg1 = MI->getOperand(1).getReg();
if (Reg0 != Reg1)
return false;
if (Entry.LowRegs2 && !isARMLowRegister(Reg0))
return false;
if (Entry.Imm2Limit) {
unsigned Imm = MI->getOperand(2).getImm();
unsigned Limit = (1 << Entry.Imm2Limit) - 1;
if (Imm > Limit)
return false;
} else {
unsigned Reg2 = MI->getOperand(2).getReg();
if (Entry.LowRegs2 && !isARMLowRegister(Reg2))
return false;
}
// Check if it's possible / necessary to transfer the predicate.
const TargetInstrDesc &NewTID = TII->get(Entry.NarrowOpc2);
unsigned PredReg = 0;
ARMCC::CondCodes Pred = getInstrPredicate(MI, PredReg);
bool SkipPred = false;
if (Pred != ARMCC::AL) {
if (!NewTID.isPredicable())
// Can't transfer predicate, fail.
return false;
} else {
SkipPred = !NewTID.isPredicable();
}
bool HasCC = false;
bool CCDead = false;
if (TID.hasOptionalDef()) {
unsigned NumOps = TID.getNumOperands();
HasCC = (MI->getOperand(NumOps-1).getReg() == ARM::CPSR);
if (HasCC && MI->getOperand(NumOps-1).isDead())
CCDead = true;
}
if (!VerifyPredAndCC(MI, Entry, true, Pred, LiveCPSR, HasCC, CCDead))
return false;
// Add the 16-bit instruction.
DebugLoc dl = MI->getDebugLoc();
MachineInstrBuilder MIB = BuildMI(MBB, *MI, dl, NewTID);
MIB.addOperand(MI->getOperand(0));
if (NewTID.hasOptionalDef()) {
if (HasCC)
AddDefaultT1CC(MIB, CCDead);
else
AddNoT1CC(MIB);
}
// Transfer the rest of operands.
unsigned NumOps = TID.getNumOperands();
for (unsigned i = 1, e = MI->getNumOperands(); i != e; ++i) {
if (i < NumOps && TID.OpInfo[i].isOptionalDef())
continue;
if (SkipPred && TID.OpInfo[i].isPredicate())
continue;
MIB.addOperand(MI->getOperand(i));
}
DEBUG(errs() << "Converted 32-bit: " << *MI << " to 16-bit: " << *MIB);
MBB.erase(MI);
++Num2Addrs;
return true;
}
bool
Thumb2SizeReduce::ReduceToNarrow(MachineBasicBlock &MBB, MachineInstr *MI,
const ReduceEntry &Entry,
bool LiveCPSR) {
if (ReduceLimit != -1 && ((int)NumNarrows >= ReduceLimit))
return false;
unsigned Limit = ~0U;
unsigned Scale = (Entry.WideOpc == ARM::t2ADDrSPi) ? 4 : 1;
if (Entry.Imm1Limit)
Limit = ((1 << Entry.Imm1Limit) - 1) * Scale;
const TargetInstrDesc &TID = MI->getDesc();
for (unsigned i = 0, e = TID.getNumOperands(); i != e; ++i) {
if (TID.OpInfo[i].isPredicate())
continue;
const MachineOperand &MO = MI->getOperand(i);
if (MO.isReg()) {
unsigned Reg = MO.getReg();
if (!Reg || Reg == ARM::CPSR)
continue;
if (Entry.WideOpc == ARM::t2ADDrSPi && Reg == ARM::SP)
continue;
if (Entry.LowRegs1 && !isARMLowRegister(Reg))
return false;
} else if (MO.isImm() &&
!TID.OpInfo[i].isPredicate()) {
if (((unsigned)MO.getImm()) > Limit || (MO.getImm() & (Scale-1)) != 0)
return false;
}
}
// Check if it's possible / necessary to transfer the predicate.
const TargetInstrDesc &NewTID = TII->get(Entry.NarrowOpc1);
unsigned PredReg = 0;
ARMCC::CondCodes Pred = getInstrPredicate(MI, PredReg);
bool SkipPred = false;
if (Pred != ARMCC::AL) {
if (!NewTID.isPredicable())
// Can't transfer predicate, fail.
return false;
} else {
SkipPred = !NewTID.isPredicable();
}
bool HasCC = false;
bool CCDead = false;
if (TID.hasOptionalDef()) {
unsigned NumOps = TID.getNumOperands();
HasCC = (MI->getOperand(NumOps-1).getReg() == ARM::CPSR);
if (HasCC && MI->getOperand(NumOps-1).isDead())
CCDead = true;
}
if (!VerifyPredAndCC(MI, Entry, false, Pred, LiveCPSR, HasCC, CCDead))
return false;
// Add the 16-bit instruction.
DebugLoc dl = MI->getDebugLoc();
MachineInstrBuilder MIB = BuildMI(MBB, *MI, dl, NewTID);
MIB.addOperand(MI->getOperand(0));
if (NewTID.hasOptionalDef()) {
if (HasCC)
AddDefaultT1CC(MIB, CCDead);
else
AddNoT1CC(MIB);
}
// Transfer the rest of operands.
unsigned NumOps = TID.getNumOperands();
for (unsigned i = 1, e = MI->getNumOperands(); i != e; ++i) {
if (i < NumOps && TID.OpInfo[i].isOptionalDef())
continue;
if ((TID.getOpcode() == ARM::t2RSBSri ||
TID.getOpcode() == ARM::t2RSBri) && i == 2)
// Skip the zero immediate operand, it's now implicit.
continue;
bool isPred = (i < NumOps && TID.OpInfo[i].isPredicate());
if (SkipPred && isPred)
continue;
const MachineOperand &MO = MI->getOperand(i);
if (Scale > 1 && !isPred && MO.isImm())
MIB.addImm(MO.getImm() / Scale);
else {
if (MO.isReg() && MO.isImplicit() && MO.getReg() == ARM::CPSR)
// Skip implicit def of CPSR. Either it's modeled as an optional
// def now or it's already an implicit def on the new instruction.
continue;
MIB.addOperand(MO);
}
}
if (!TID.isPredicable() && NewTID.isPredicable())
AddDefaultPred(MIB);
DEBUG(errs() << "Converted 32-bit: " << *MI << " to 16-bit: " << *MIB);
MBB.erase(MI);
++NumNarrows;
return true;
}
static bool UpdateCPSRDef(MachineInstr &MI, bool LiveCPSR) {
bool HasDef = false;
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI.getOperand(i);
if (!MO.isReg() || MO.isUndef() || MO.isUse())
continue;
if (MO.getReg() != ARM::CPSR)
continue;
if (!MO.isDead())
HasDef = true;
}
return HasDef || LiveCPSR;
}
static bool UpdateCPSRUse(MachineInstr &MI, bool LiveCPSR) {
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI.getOperand(i);
if (!MO.isReg() || MO.isUndef() || MO.isDef())
continue;
if (MO.getReg() != ARM::CPSR)
continue;
assert(LiveCPSR && "CPSR liveness tracking is wrong!");
if (MO.isKill()) {
LiveCPSR = false;
break;
}
}
return LiveCPSR;
}
bool Thumb2SizeReduce::ReduceMBB(MachineBasicBlock &MBB) {
bool Modified = false;
bool LiveCPSR = false;
// Yes, CPSR could be livein.
for (MachineBasicBlock::const_livein_iterator I = MBB.livein_begin(),
E = MBB.livein_end(); I != E; ++I) {
if (*I == ARM::CPSR) {
LiveCPSR = true;
break;
}
}
MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
MachineBasicBlock::iterator NextMII;
for (; MII != E; MII = NextMII) {
NextMII = llvm::next(MII);
MachineInstr *MI = &*MII;
LiveCPSR = UpdateCPSRUse(*MI, LiveCPSR);
unsigned Opcode = MI->getOpcode();
DenseMap<unsigned, unsigned>::iterator OPI = ReduceOpcodeMap.find(Opcode);
if (OPI != ReduceOpcodeMap.end()) {
const ReduceEntry &Entry = ReduceTable[OPI->second];
// Ignore "special" cases for now.
if (Entry.Special) {
if (ReduceSpecial(MBB, MI, Entry, LiveCPSR)) {
Modified = true;
MachineBasicBlock::iterator I = prior(NextMII);
MI = &*I;
}
goto ProcessNext;
}
// Try to transform to a 16-bit two-address instruction.
if (Entry.NarrowOpc2 && ReduceTo2Addr(MBB, MI, Entry, LiveCPSR)) {
Modified = true;
MachineBasicBlock::iterator I = prior(NextMII);
MI = &*I;
goto ProcessNext;
}
// Try to transform ro a 16-bit non-two-address instruction.
if (Entry.NarrowOpc1 && ReduceToNarrow(MBB, MI, Entry, LiveCPSR)) {
Modified = true;
MachineBasicBlock::iterator I = prior(NextMII);
MI = &*I;
}
}
ProcessNext:
LiveCPSR = UpdateCPSRDef(*MI, LiveCPSR);
}
return Modified;
}
bool Thumb2SizeReduce::runOnMachineFunction(MachineFunction &MF) {
const TargetMachine &TM = MF.getTarget();
TII = static_cast<const Thumb2InstrInfo*>(TM.getInstrInfo());
bool Modified = false;
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
Modified |= ReduceMBB(*I);
return Modified;
}
/// createThumb2SizeReductionPass - Returns an instance of the Thumb2 size
/// reduction pass.
FunctionPass *llvm::createThumb2SizeReductionPass() {
return new Thumb2SizeReduce();
}
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