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llvm-mirror/lib/Target/Hexagon/HexagonBitSimplify.cpp
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo 
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

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//===- HexagonBitSimplify.cpp ---------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "BitTracker.h"
#include "HexagonBitTracker.h"
#include "HexagonInstrInfo.h"
#include "HexagonRegisterInfo.h"
#include "HexagonSubtarget.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <iterator>
#include <limits>
#include <utility>
#include <vector>
#define DEBUG_TYPE "hexbit"
using namespace llvm;
static cl::opt<bool> PreserveTiedOps("hexbit-keep-tied", cl::Hidden,
cl::init(true), cl::desc("Preserve subregisters in tied operands"));
static cl::opt<bool> GenExtract("hexbit-extract", cl::Hidden,
cl::init(true), cl::desc("Generate extract instructions"));
static cl::opt<bool> GenBitSplit("hexbit-bitsplit", cl::Hidden,
cl::init(true), cl::desc("Generate bitsplit instructions"));
static cl::opt<unsigned> MaxExtract("hexbit-max-extract", cl::Hidden,
cl::init(std::numeric_limits<unsigned>::max()));
static unsigned CountExtract = 0;
static cl::opt<unsigned> MaxBitSplit("hexbit-max-bitsplit", cl::Hidden,
cl::init(std::numeric_limits<unsigned>::max()));
static unsigned CountBitSplit = 0;
namespace llvm {
void initializeHexagonBitSimplifyPass(PassRegistry& Registry);
FunctionPass *createHexagonBitSimplify();
} // end namespace llvm
namespace {
// Set of virtual registers, based on BitVector.
struct RegisterSet : private BitVector {
RegisterSet() = default;
explicit RegisterSet(unsigned s, bool t = false) : BitVector(s, t) {}
RegisterSet(const RegisterSet &RS) = default;
using BitVector::clear;
using BitVector::count;
unsigned find_first() const {
int First = BitVector::find_first();
if (First < 0)
return 0;
return x2v(First);
}
unsigned find_next(unsigned Prev) const {
int Next = BitVector::find_next(v2x(Prev));
if (Next < 0)
return 0;
return x2v(Next);
}
RegisterSet &insert(unsigned R) {
unsigned Idx = v2x(R);
ensure(Idx);
return static_cast<RegisterSet&>(BitVector::set(Idx));
}
RegisterSet &remove(unsigned R) {
unsigned Idx = v2x(R);
if (Idx >= size())
return *this;
return static_cast<RegisterSet&>(BitVector::reset(Idx));
}
RegisterSet &insert(const RegisterSet &Rs) {
return static_cast<RegisterSet&>(BitVector::operator|=(Rs));
}
RegisterSet &remove(const RegisterSet &Rs) {
return static_cast<RegisterSet&>(BitVector::reset(Rs));
}
reference operator[](unsigned R) {
unsigned Idx = v2x(R);
ensure(Idx);
return BitVector::operator[](Idx);
}
bool operator[](unsigned R) const {
unsigned Idx = v2x(R);
assert(Idx < size());
return BitVector::operator[](Idx);
}
bool has(unsigned R) const {
unsigned Idx = v2x(R);
if (Idx >= size())
return false;
return BitVector::test(Idx);
}
bool empty() const {
return !BitVector::any();
}
bool includes(const RegisterSet &Rs) const {
// A.BitVector::test(B) <=> A-B != {}
return !Rs.BitVector::test(*this);
}
bool intersects(const RegisterSet &Rs) const {
return BitVector::anyCommon(Rs);
}
private:
void ensure(unsigned Idx) {
if (size() <= Idx)
resize(std::max(Idx+1, 32U));
}
static inline unsigned v2x(unsigned v) {
return TargetRegisterInfo::virtReg2Index(v);
}
static inline unsigned x2v(unsigned x) {
return TargetRegisterInfo::index2VirtReg(x);
}
};
struct PrintRegSet {
PrintRegSet(const RegisterSet &S, const TargetRegisterInfo *RI)
: RS(S), TRI(RI) {}
friend raw_ostream &operator<< (raw_ostream &OS,
const PrintRegSet &P);
private:
const RegisterSet &RS;
const TargetRegisterInfo *TRI;
};
raw_ostream &operator<< (raw_ostream &OS, const PrintRegSet &P)
LLVM_ATTRIBUTE_UNUSED;
raw_ostream &operator<< (raw_ostream &OS, const PrintRegSet &P) {
OS << '{';
for (unsigned R = P.RS.find_first(); R; R = P.RS.find_next(R))
OS << ' ' << printReg(R, P.TRI);
OS << " }";
return OS;
}
class Transformation;
class HexagonBitSimplify : public MachineFunctionPass {
public:
static char ID;
HexagonBitSimplify() : MachineFunctionPass(ID) {}
StringRef getPassName() const override {
return "Hexagon bit simplification";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<MachineDominatorTree>();
AU.addPreserved<MachineDominatorTree>();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool runOnMachineFunction(MachineFunction &MF) override;
static void getInstrDefs(const MachineInstr &MI, RegisterSet &Defs);
static void getInstrUses(const MachineInstr &MI, RegisterSet &Uses);
static bool isEqual(const BitTracker::RegisterCell &RC1, uint16_t B1,
const BitTracker::RegisterCell &RC2, uint16_t B2, uint16_t W);
static bool isZero(const BitTracker::RegisterCell &RC, uint16_t B,
uint16_t W);
static bool getConst(const BitTracker::RegisterCell &RC, uint16_t B,
uint16_t W, uint64_t &U);
static bool replaceReg(unsigned OldR, unsigned NewR,
MachineRegisterInfo &MRI);
static bool getSubregMask(const BitTracker::RegisterRef &RR,
unsigned &Begin, unsigned &Width, MachineRegisterInfo &MRI);
static bool replaceRegWithSub(unsigned OldR, unsigned NewR,
unsigned NewSR, MachineRegisterInfo &MRI);
static bool replaceSubWithSub(unsigned OldR, unsigned OldSR,
unsigned NewR, unsigned NewSR, MachineRegisterInfo &MRI);
static bool parseRegSequence(const MachineInstr &I,
BitTracker::RegisterRef &SL, BitTracker::RegisterRef &SH,
const MachineRegisterInfo &MRI);
static bool getUsedBitsInStore(unsigned Opc, BitVector &Bits,
uint16_t Begin);
static bool getUsedBits(unsigned Opc, unsigned OpN, BitVector &Bits,
uint16_t Begin, const HexagonInstrInfo &HII);
static const TargetRegisterClass *getFinalVRegClass(
const BitTracker::RegisterRef &RR, MachineRegisterInfo &MRI);
static bool isTransparentCopy(const BitTracker::RegisterRef &RD,
const BitTracker::RegisterRef &RS, MachineRegisterInfo &MRI);
private:
MachineDominatorTree *MDT = nullptr;
bool visitBlock(MachineBasicBlock &B, Transformation &T, RegisterSet &AVs);
static bool hasTiedUse(unsigned Reg, MachineRegisterInfo &MRI,
unsigned NewSub = Hexagon::NoSubRegister);
};
using HBS = HexagonBitSimplify;
// The purpose of this class is to provide a common facility to traverse
// the function top-down or bottom-up via the dominator tree, and keep
// track of the available registers.
class Transformation {
public:
bool TopDown;
Transformation(bool TD) : TopDown(TD) {}
virtual ~Transformation() = default;
virtual bool processBlock(MachineBasicBlock &B, const RegisterSet &AVs) = 0;
};
} // end anonymous namespace
char HexagonBitSimplify::ID = 0;
INITIALIZE_PASS_BEGIN(HexagonBitSimplify, "hexagon-bit-simplify",
"Hexagon bit simplification", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_END(HexagonBitSimplify, "hexagon-bit-simplify",
"Hexagon bit simplification", false, false)
bool HexagonBitSimplify::visitBlock(MachineBasicBlock &B, Transformation &T,
RegisterSet &AVs) {
bool Changed = false;
if (T.TopDown)
Changed = T.processBlock(B, AVs);
RegisterSet Defs;
for (auto &I : B)
getInstrDefs(I, Defs);
RegisterSet NewAVs = AVs;
NewAVs.insert(Defs);
for (auto *DTN : children<MachineDomTreeNode*>(MDT->getNode(&B)))
Changed |= visitBlock(*(DTN->getBlock()), T, NewAVs);
if (!T.TopDown)
Changed |= T.processBlock(B, AVs);
return Changed;
}
//
// Utility functions:
//
void HexagonBitSimplify::getInstrDefs(const MachineInstr &MI,
RegisterSet &Defs) {
for (auto &Op : MI.operands()) {
if (!Op.isReg() || !Op.isDef())
continue;
unsigned R = Op.getReg();
if (!TargetRegisterInfo::isVirtualRegister(R))
continue;
Defs.insert(R);
}
}
void HexagonBitSimplify::getInstrUses(const MachineInstr &MI,
RegisterSet &Uses) {
for (auto &Op : MI.operands()) {
if (!Op.isReg() || !Op.isUse())
continue;
unsigned R = Op.getReg();
if (!TargetRegisterInfo::isVirtualRegister(R))
continue;
Uses.insert(R);
}
}
// Check if all the bits in range [B, E) in both cells are equal.
bool HexagonBitSimplify::isEqual(const BitTracker::RegisterCell &RC1,
uint16_t B1, const BitTracker::RegisterCell &RC2, uint16_t B2,
uint16_t W) {
for (uint16_t i = 0; i < W; ++i) {
// If RC1[i] is "bottom", it cannot be proven equal to RC2[i].
if (RC1[B1+i].Type == BitTracker::BitValue::Ref && RC1[B1+i].RefI.Reg == 0)
return false;
// Same for RC2[i].
if (RC2[B2+i].Type == BitTracker::BitValue::Ref && RC2[B2+i].RefI.Reg == 0)
return false;
if (RC1[B1+i] != RC2[B2+i])
return false;
}
return true;
}
bool HexagonBitSimplify::isZero(const BitTracker::RegisterCell &RC,
uint16_t B, uint16_t W) {
assert(B < RC.width() && B+W <= RC.width());
for (uint16_t i = B; i < B+W; ++i)
if (!RC[i].is(0))
return false;
return true;
}
bool HexagonBitSimplify::getConst(const BitTracker::RegisterCell &RC,
uint16_t B, uint16_t W, uint64_t &U) {
assert(B < RC.width() && B+W <= RC.width());
int64_t T = 0;
for (uint16_t i = B+W; i > B; --i) {
const BitTracker::BitValue &BV = RC[i-1];
T <<= 1;
if (BV.is(1))
T |= 1;
else if (!BV.is(0))
return false;
}
U = T;
return true;
}
bool HexagonBitSimplify::replaceReg(unsigned OldR, unsigned NewR,
MachineRegisterInfo &MRI) {
if (!TargetRegisterInfo::isVirtualRegister(OldR) ||
!TargetRegisterInfo::isVirtualRegister(NewR))
return false;
auto Begin = MRI.use_begin(OldR), End = MRI.use_end();
decltype(End) NextI;
for (auto I = Begin; I != End; I = NextI) {
NextI = std::next(I);
I->setReg(NewR);
}
return Begin != End;
}
bool HexagonBitSimplify::replaceRegWithSub(unsigned OldR, unsigned NewR,
unsigned NewSR, MachineRegisterInfo &MRI) {
if (!TargetRegisterInfo::isVirtualRegister(OldR) ||
!TargetRegisterInfo::isVirtualRegister(NewR))
return false;
if (hasTiedUse(OldR, MRI, NewSR))
return false;
auto Begin = MRI.use_begin(OldR), End = MRI.use_end();
decltype(End) NextI;
for (auto I = Begin; I != End; I = NextI) {
NextI = std::next(I);
I->setReg(NewR);
I->setSubReg(NewSR);
}
return Begin != End;
}
bool HexagonBitSimplify::replaceSubWithSub(unsigned OldR, unsigned OldSR,
unsigned NewR, unsigned NewSR, MachineRegisterInfo &MRI) {
if (!TargetRegisterInfo::isVirtualRegister(OldR) ||
!TargetRegisterInfo::isVirtualRegister(NewR))
return false;
if (OldSR != NewSR && hasTiedUse(OldR, MRI, NewSR))
return false;
auto Begin = MRI.use_begin(OldR), End = MRI.use_end();
decltype(End) NextI;
for (auto I = Begin; I != End; I = NextI) {
NextI = std::next(I);
if (I->getSubReg() != OldSR)
continue;
I->setReg(NewR);
I->setSubReg(NewSR);
}
return Begin != End;
}
// For a register ref (pair Reg:Sub), set Begin to the position of the LSB
// of Sub in Reg, and set Width to the size of Sub in bits. Return true,
// if this succeeded, otherwise return false.
bool HexagonBitSimplify::getSubregMask(const BitTracker::RegisterRef &RR,
unsigned &Begin, unsigned &Width, MachineRegisterInfo &MRI) {
const TargetRegisterClass *RC = MRI.getRegClass(RR.Reg);
if (RR.Sub == 0) {
Begin = 0;
Width = MRI.getTargetRegisterInfo()->getRegSizeInBits(*RC);
return true;
}
Begin = 0;
switch (RC->getID()) {
case Hexagon::DoubleRegsRegClassID:
case Hexagon::HvxWRRegClassID:
Width = MRI.getTargetRegisterInfo()->getRegSizeInBits(*RC) / 2;
if (RR.Sub == Hexagon::isub_hi || RR.Sub == Hexagon::vsub_hi)
Begin = Width;
break;
default:
return false;
}
return true;
}
// For a REG_SEQUENCE, set SL to the low subregister and SH to the high
// subregister.
bool HexagonBitSimplify::parseRegSequence(const MachineInstr &I,
BitTracker::RegisterRef &SL, BitTracker::RegisterRef &SH,
const MachineRegisterInfo &MRI) {
assert(I.getOpcode() == TargetOpcode::REG_SEQUENCE);
unsigned Sub1 = I.getOperand(2).getImm(), Sub2 = I.getOperand(4).getImm();
auto &DstRC = *MRI.getRegClass(I.getOperand(0).getReg());
auto &HRI = static_cast<const HexagonRegisterInfo&>(
*MRI.getTargetRegisterInfo());
unsigned SubLo = HRI.getHexagonSubRegIndex(DstRC, Hexagon::ps_sub_lo);
unsigned SubHi = HRI.getHexagonSubRegIndex(DstRC, Hexagon::ps_sub_hi);
assert((Sub1 == SubLo && Sub2 == SubHi) || (Sub1 == SubHi && Sub2 == SubLo));
if (Sub1 == SubLo && Sub2 == SubHi) {
SL = I.getOperand(1);
SH = I.getOperand(3);
return true;
}
if (Sub1 == SubHi && Sub2 == SubLo) {
SH = I.getOperand(1);
SL = I.getOperand(3);
return true;
}
return false;
}
// All stores (except 64-bit stores) take a 32-bit register as the source
// of the value to be stored. If the instruction stores into a location
// that is shorter than 32 bits, some bits of the source register are not
// used. For each store instruction, calculate the set of used bits in
// the source register, and set appropriate bits in Bits. Return true if
// the bits are calculated, false otherwise.
bool HexagonBitSimplify::getUsedBitsInStore(unsigned Opc, BitVector &Bits,
uint16_t Begin) {
using namespace Hexagon;
switch (Opc) {
// Store byte
case S2_storerb_io: // memb(Rs32+#s11:0)=Rt32
case S2_storerbnew_io: // memb(Rs32+#s11:0)=Nt8.new
case S2_pstorerbt_io: // if (Pv4) memb(Rs32+#u6:0)=Rt32
case S2_pstorerbf_io: // if (!Pv4) memb(Rs32+#u6:0)=Rt32
case S4_pstorerbtnew_io: // if (Pv4.new) memb(Rs32+#u6:0)=Rt32
case S4_pstorerbfnew_io: // if (!Pv4.new) memb(Rs32+#u6:0)=Rt32
case S2_pstorerbnewt_io: // if (Pv4) memb(Rs32+#u6:0)=Nt8.new
case S2_pstorerbnewf_io: // if (!Pv4) memb(Rs32+#u6:0)=Nt8.new
case S4_pstorerbnewtnew_io: // if (Pv4.new) memb(Rs32+#u6:0)=Nt8.new
case S4_pstorerbnewfnew_io: // if (!Pv4.new) memb(Rs32+#u6:0)=Nt8.new
case S2_storerb_pi: // memb(Rx32++#s4:0)=Rt32
case S2_storerbnew_pi: // memb(Rx32++#s4:0)=Nt8.new
case S2_pstorerbt_pi: // if (Pv4) memb(Rx32++#s4:0)=Rt32
case S2_pstorerbf_pi: // if (!Pv4) memb(Rx32++#s4:0)=Rt32
case S2_pstorerbtnew_pi: // if (Pv4.new) memb(Rx32++#s4:0)=Rt32
case S2_pstorerbfnew_pi: // if (!Pv4.new) memb(Rx32++#s4:0)=Rt32
case S2_pstorerbnewt_pi: // if (Pv4) memb(Rx32++#s4:0)=Nt8.new
case S2_pstorerbnewf_pi: // if (!Pv4) memb(Rx32++#s4:0)=Nt8.new
case S2_pstorerbnewtnew_pi: // if (Pv4.new) memb(Rx32++#s4:0)=Nt8.new
case S2_pstorerbnewfnew_pi: // if (!Pv4.new) memb(Rx32++#s4:0)=Nt8.new
case S4_storerb_ap: // memb(Re32=#U6)=Rt32
case S4_storerbnew_ap: // memb(Re32=#U6)=Nt8.new
case S2_storerb_pr: // memb(Rx32++Mu2)=Rt32
case S2_storerbnew_pr: // memb(Rx32++Mu2)=Nt8.new
case S4_storerb_ur: // memb(Ru32<<#u2+#U6)=Rt32
case S4_storerbnew_ur: // memb(Ru32<<#u2+#U6)=Nt8.new
case S2_storerb_pbr: // memb(Rx32++Mu2:brev)=Rt32
case S2_storerbnew_pbr: // memb(Rx32++Mu2:brev)=Nt8.new
case S2_storerb_pci: // memb(Rx32++#s4:0:circ(Mu2))=Rt32
case S2_storerbnew_pci: // memb(Rx32++#s4:0:circ(Mu2))=Nt8.new
case S2_storerb_pcr: // memb(Rx32++I:circ(Mu2))=Rt32
case S2_storerbnew_pcr: // memb(Rx32++I:circ(Mu2))=Nt8.new
case S4_storerb_rr: // memb(Rs32+Ru32<<#u2)=Rt32
case S4_storerbnew_rr: // memb(Rs32+Ru32<<#u2)=Nt8.new
case S4_pstorerbt_rr: // if (Pv4) memb(Rs32+Ru32<<#u2)=Rt32
case S4_pstorerbf_rr: // if (!Pv4) memb(Rs32+Ru32<<#u2)=Rt32
case S4_pstorerbtnew_rr: // if (Pv4.new) memb(Rs32+Ru32<<#u2)=Rt32
case S4_pstorerbfnew_rr: // if (!Pv4.new) memb(Rs32+Ru32<<#u2)=Rt32
case S4_pstorerbnewt_rr: // if (Pv4) memb(Rs32+Ru32<<#u2)=Nt8.new
case S4_pstorerbnewf_rr: // if (!Pv4) memb(Rs32+Ru32<<#u2)=Nt8.new
case S4_pstorerbnewtnew_rr: // if (Pv4.new) memb(Rs32+Ru32<<#u2)=Nt8.new
case S4_pstorerbnewfnew_rr: // if (!Pv4.new) memb(Rs32+Ru32<<#u2)=Nt8.new
case S2_storerbgp: // memb(gp+#u16:0)=Rt32
case S2_storerbnewgp: // memb(gp+#u16:0)=Nt8.new
case S4_pstorerbt_abs: // if (Pv4) memb(#u6)=Rt32
case S4_pstorerbf_abs: // if (!Pv4) memb(#u6)=Rt32
case S4_pstorerbtnew_abs: // if (Pv4.new) memb(#u6)=Rt32
case S4_pstorerbfnew_abs: // if (!Pv4.new) memb(#u6)=Rt32
case S4_pstorerbnewt_abs: // if (Pv4) memb(#u6)=Nt8.new
case S4_pstorerbnewf_abs: // if (!Pv4) memb(#u6)=Nt8.new
case S4_pstorerbnewtnew_abs: // if (Pv4.new) memb(#u6)=Nt8.new
case S4_pstorerbnewfnew_abs: // if (!Pv4.new) memb(#u6)=Nt8.new
Bits.set(Begin, Begin+8);
return true;
// Store low half
case S2_storerh_io: // memh(Rs32+#s11:1)=Rt32
case S2_storerhnew_io: // memh(Rs32+#s11:1)=Nt8.new
case S2_pstorerht_io: // if (Pv4) memh(Rs32+#u6:1)=Rt32
case S2_pstorerhf_io: // if (!Pv4) memh(Rs32+#u6:1)=Rt32
case S4_pstorerhtnew_io: // if (Pv4.new) memh(Rs32+#u6:1)=Rt32
case S4_pstorerhfnew_io: // if (!Pv4.new) memh(Rs32+#u6:1)=Rt32
case S2_pstorerhnewt_io: // if (Pv4) memh(Rs32+#u6:1)=Nt8.new
case S2_pstorerhnewf_io: // if (!Pv4) memh(Rs32+#u6:1)=Nt8.new
case S4_pstorerhnewtnew_io: // if (Pv4.new) memh(Rs32+#u6:1)=Nt8.new
case S4_pstorerhnewfnew_io: // if (!Pv4.new) memh(Rs32+#u6:1)=Nt8.new
case S2_storerh_pi: // memh(Rx32++#s4:1)=Rt32
case S2_storerhnew_pi: // memh(Rx32++#s4:1)=Nt8.new
case S2_pstorerht_pi: // if (Pv4) memh(Rx32++#s4:1)=Rt32
case S2_pstorerhf_pi: // if (!Pv4) memh(Rx32++#s4:1)=Rt32
case S2_pstorerhtnew_pi: // if (Pv4.new) memh(Rx32++#s4:1)=Rt32
case S2_pstorerhfnew_pi: // if (!Pv4.new) memh(Rx32++#s4:1)=Rt32
case S2_pstorerhnewt_pi: // if (Pv4) memh(Rx32++#s4:1)=Nt8.new
case S2_pstorerhnewf_pi: // if (!Pv4) memh(Rx32++#s4:1)=Nt8.new
case S2_pstorerhnewtnew_pi: // if (Pv4.new) memh(Rx32++#s4:1)=Nt8.new
case S2_pstorerhnewfnew_pi: // if (!Pv4.new) memh(Rx32++#s4:1)=Nt8.new
case S4_storerh_ap: // memh(Re32=#U6)=Rt32
case S4_storerhnew_ap: // memh(Re32=#U6)=Nt8.new
case S2_storerh_pr: // memh(Rx32++Mu2)=Rt32
case S2_storerhnew_pr: // memh(Rx32++Mu2)=Nt8.new
case S4_storerh_ur: // memh(Ru32<<#u2+#U6)=Rt32
case S4_storerhnew_ur: // memh(Ru32<<#u2+#U6)=Nt8.new
case S2_storerh_pbr: // memh(Rx32++Mu2:brev)=Rt32
case S2_storerhnew_pbr: // memh(Rx32++Mu2:brev)=Nt8.new
case S2_storerh_pci: // memh(Rx32++#s4:1:circ(Mu2))=Rt32
case S2_storerhnew_pci: // memh(Rx32++#s4:1:circ(Mu2))=Nt8.new
case S2_storerh_pcr: // memh(Rx32++I:circ(Mu2))=Rt32
case S2_storerhnew_pcr: // memh(Rx32++I:circ(Mu2))=Nt8.new
case S4_storerh_rr: // memh(Rs32+Ru32<<#u2)=Rt32
case S4_pstorerht_rr: // if (Pv4) memh(Rs32+Ru32<<#u2)=Rt32
case S4_pstorerhf_rr: // if (!Pv4) memh(Rs32+Ru32<<#u2)=Rt32
case S4_pstorerhtnew_rr: // if (Pv4.new) memh(Rs32+Ru32<<#u2)=Rt32
case S4_pstorerhfnew_rr: // if (!Pv4.new) memh(Rs32+Ru32<<#u2)=Rt32
case S4_storerhnew_rr: // memh(Rs32+Ru32<<#u2)=Nt8.new
case S4_pstorerhnewt_rr: // if (Pv4) memh(Rs32+Ru32<<#u2)=Nt8.new
case S4_pstorerhnewf_rr: // if (!Pv4) memh(Rs32+Ru32<<#u2)=Nt8.new
case S4_pstorerhnewtnew_rr: // if (Pv4.new) memh(Rs32+Ru32<<#u2)=Nt8.new
case S4_pstorerhnewfnew_rr: // if (!Pv4.new) memh(Rs32+Ru32<<#u2)=Nt8.new
case S2_storerhgp: // memh(gp+#u16:1)=Rt32
case S2_storerhnewgp: // memh(gp+#u16:1)=Nt8.new
case S4_pstorerht_abs: // if (Pv4) memh(#u6)=Rt32
case S4_pstorerhf_abs: // if (!Pv4) memh(#u6)=Rt32
case S4_pstorerhtnew_abs: // if (Pv4.new) memh(#u6)=Rt32
case S4_pstorerhfnew_abs: // if (!Pv4.new) memh(#u6)=Rt32
case S4_pstorerhnewt_abs: // if (Pv4) memh(#u6)=Nt8.new
case S4_pstorerhnewf_abs: // if (!Pv4) memh(#u6)=Nt8.new
case S4_pstorerhnewtnew_abs: // if (Pv4.new) memh(#u6)=Nt8.new
case S4_pstorerhnewfnew_abs: // if (!Pv4.new) memh(#u6)=Nt8.new
Bits.set(Begin, Begin+16);
return true;
// Store high half
case S2_storerf_io: // memh(Rs32+#s11:1)=Rt.H32
case S2_pstorerft_io: // if (Pv4) memh(Rs32+#u6:1)=Rt.H32
case S2_pstorerff_io: // if (!Pv4) memh(Rs32+#u6:1)=Rt.H32
case S4_pstorerftnew_io: // if (Pv4.new) memh(Rs32+#u6:1)=Rt.H32
case S4_pstorerffnew_io: // if (!Pv4.new) memh(Rs32+#u6:1)=Rt.H32
case S2_storerf_pi: // memh(Rx32++#s4:1)=Rt.H32
case S2_pstorerft_pi: // if (Pv4) memh(Rx32++#s4:1)=Rt.H32
case S2_pstorerff_pi: // if (!Pv4) memh(Rx32++#s4:1)=Rt.H32
case S2_pstorerftnew_pi: // if (Pv4.new) memh(Rx32++#s4:1)=Rt.H32
case S2_pstorerffnew_pi: // if (!Pv4.new) memh(Rx32++#s4:1)=Rt.H32
case S4_storerf_ap: // memh(Re32=#U6)=Rt.H32
case S2_storerf_pr: // memh(Rx32++Mu2)=Rt.H32
case S4_storerf_ur: // memh(Ru32<<#u2+#U6)=Rt.H32
case S2_storerf_pbr: // memh(Rx32++Mu2:brev)=Rt.H32
case S2_storerf_pci: // memh(Rx32++#s4:1:circ(Mu2))=Rt.H32
case S2_storerf_pcr: // memh(Rx32++I:circ(Mu2))=Rt.H32
case S4_storerf_rr: // memh(Rs32+Ru32<<#u2)=Rt.H32
case S4_pstorerft_rr: // if (Pv4) memh(Rs32+Ru32<<#u2)=Rt.H32
case S4_pstorerff_rr: // if (!Pv4) memh(Rs32+Ru32<<#u2)=Rt.H32
case S4_pstorerftnew_rr: // if (Pv4.new) memh(Rs32+Ru32<<#u2)=Rt.H32
case S4_pstorerffnew_rr: // if (!Pv4.new) memh(Rs32+Ru32<<#u2)=Rt.H32
case S2_storerfgp: // memh(gp+#u16:1)=Rt.H32
case S4_pstorerft_abs: // if (Pv4) memh(#u6)=Rt.H32
case S4_pstorerff_abs: // if (!Pv4) memh(#u6)=Rt.H32
case S4_pstorerftnew_abs: // if (Pv4.new) memh(#u6)=Rt.H32
case S4_pstorerffnew_abs: // if (!Pv4.new) memh(#u6)=Rt.H32
Bits.set(Begin+16, Begin+32);
return true;
}
return false;
}
// For an instruction with opcode Opc, calculate the set of bits that it
// uses in a register in operand OpN. This only calculates the set of used
// bits for cases where it does not depend on any operands (as is the case
// in shifts, for example). For concrete instructions from a program, the
// operand may be a subregister of a larger register, while Bits would
// correspond to the larger register in its entirety. Because of that,
// the parameter Begin can be used to indicate which bit of Bits should be
// considered the LSB of the operand.
bool HexagonBitSimplify::getUsedBits(unsigned Opc, unsigned OpN,
BitVector &Bits, uint16_t Begin, const HexagonInstrInfo &HII) {
using namespace Hexagon;
const MCInstrDesc &D = HII.get(Opc);
if (D.mayStore()) {
if (OpN == D.getNumOperands()-1)
return getUsedBitsInStore(Opc, Bits, Begin);
return false;
}
switch (Opc) {
// One register source. Used bits: R1[0-7].
case A2_sxtb:
case A2_zxtb:
case A4_cmpbeqi:
case A4_cmpbgti:
case A4_cmpbgtui:
if (OpN == 1) {
Bits.set(Begin, Begin+8);
return true;
}
break;
// One register source. Used bits: R1[0-15].
case A2_aslh:
case A2_sxth:
case A2_zxth:
case A4_cmpheqi:
case A4_cmphgti:
case A4_cmphgtui:
if (OpN == 1) {
Bits.set(Begin, Begin+16);
return true;
}
break;
// One register source. Used bits: R1[16-31].
case A2_asrh:
if (OpN == 1) {
Bits.set(Begin+16, Begin+32);
return true;
}
break;
// Two register sources. Used bits: R1[0-7], R2[0-7].
case A4_cmpbeq:
case A4_cmpbgt:
case A4_cmpbgtu:
if (OpN == 1) {
Bits.set(Begin, Begin+8);
return true;
}
break;
// Two register sources. Used bits: R1[0-15], R2[0-15].
case A4_cmpheq:
case A4_cmphgt:
case A4_cmphgtu:
case A2_addh_h16_ll:
case A2_addh_h16_sat_ll:
case A2_addh_l16_ll:
case A2_addh_l16_sat_ll:
case A2_combine_ll:
case A2_subh_h16_ll:
case A2_subh_h16_sat_ll:
case A2_subh_l16_ll:
case A2_subh_l16_sat_ll:
case M2_mpy_acc_ll_s0:
case M2_mpy_acc_ll_s1:
case M2_mpy_acc_sat_ll_s0:
case M2_mpy_acc_sat_ll_s1:
case M2_mpy_ll_s0:
case M2_mpy_ll_s1:
case M2_mpy_nac_ll_s0:
case M2_mpy_nac_ll_s1:
case M2_mpy_nac_sat_ll_s0:
case M2_mpy_nac_sat_ll_s1:
case M2_mpy_rnd_ll_s0:
case M2_mpy_rnd_ll_s1:
case M2_mpy_sat_ll_s0:
case M2_mpy_sat_ll_s1:
case M2_mpy_sat_rnd_ll_s0:
case M2_mpy_sat_rnd_ll_s1:
case M2_mpyd_acc_ll_s0:
case M2_mpyd_acc_ll_s1:
case M2_mpyd_ll_s0:
case M2_mpyd_ll_s1:
case M2_mpyd_nac_ll_s0:
case M2_mpyd_nac_ll_s1:
case M2_mpyd_rnd_ll_s0:
case M2_mpyd_rnd_ll_s1:
case M2_mpyu_acc_ll_s0:
case M2_mpyu_acc_ll_s1:
case M2_mpyu_ll_s0:
case M2_mpyu_ll_s1:
case M2_mpyu_nac_ll_s0:
case M2_mpyu_nac_ll_s1:
case M2_mpyud_acc_ll_s0:
case M2_mpyud_acc_ll_s1:
case M2_mpyud_ll_s0:
case M2_mpyud_ll_s1:
case M2_mpyud_nac_ll_s0:
case M2_mpyud_nac_ll_s1:
if (OpN == 1 || OpN == 2) {
Bits.set(Begin, Begin+16);
return true;
}
break;
// Two register sources. Used bits: R1[0-15], R2[16-31].
case A2_addh_h16_lh:
case A2_addh_h16_sat_lh:
case A2_combine_lh:
case A2_subh_h16_lh:
case A2_subh_h16_sat_lh:
case M2_mpy_acc_lh_s0:
case M2_mpy_acc_lh_s1:
case M2_mpy_acc_sat_lh_s0:
case M2_mpy_acc_sat_lh_s1:
case M2_mpy_lh_s0:
case M2_mpy_lh_s1:
case M2_mpy_nac_lh_s0:
case M2_mpy_nac_lh_s1:
case M2_mpy_nac_sat_lh_s0:
case M2_mpy_nac_sat_lh_s1:
case M2_mpy_rnd_lh_s0:
case M2_mpy_rnd_lh_s1:
case M2_mpy_sat_lh_s0:
case M2_mpy_sat_lh_s1:
case M2_mpy_sat_rnd_lh_s0:
case M2_mpy_sat_rnd_lh_s1:
case M2_mpyd_acc_lh_s0:
case M2_mpyd_acc_lh_s1:
case M2_mpyd_lh_s0:
case M2_mpyd_lh_s1:
case M2_mpyd_nac_lh_s0:
case M2_mpyd_nac_lh_s1:
case M2_mpyd_rnd_lh_s0:
case M2_mpyd_rnd_lh_s1:
case M2_mpyu_acc_lh_s0:
case M2_mpyu_acc_lh_s1:
case M2_mpyu_lh_s0:
case M2_mpyu_lh_s1:
case M2_mpyu_nac_lh_s0:
case M2_mpyu_nac_lh_s1:
case M2_mpyud_acc_lh_s0:
case M2_mpyud_acc_lh_s1:
case M2_mpyud_lh_s0:
case M2_mpyud_lh_s1:
case M2_mpyud_nac_lh_s0:
case M2_mpyud_nac_lh_s1:
// These four are actually LH.
case A2_addh_l16_hl:
case A2_addh_l16_sat_hl:
case A2_subh_l16_hl:
case A2_subh_l16_sat_hl:
if (OpN == 1) {
Bits.set(Begin, Begin+16);
return true;
}
if (OpN == 2) {
Bits.set(Begin+16, Begin+32);
return true;
}
break;
// Two register sources, used bits: R1[16-31], R2[0-15].
case A2_addh_h16_hl:
case A2_addh_h16_sat_hl:
case A2_combine_hl:
case A2_subh_h16_hl:
case A2_subh_h16_sat_hl:
case M2_mpy_acc_hl_s0:
case M2_mpy_acc_hl_s1:
case M2_mpy_acc_sat_hl_s0:
case M2_mpy_acc_sat_hl_s1:
case M2_mpy_hl_s0:
case M2_mpy_hl_s1:
case M2_mpy_nac_hl_s0:
case M2_mpy_nac_hl_s1:
case M2_mpy_nac_sat_hl_s0:
case M2_mpy_nac_sat_hl_s1:
case M2_mpy_rnd_hl_s0:
case M2_mpy_rnd_hl_s1:
case M2_mpy_sat_hl_s0:
case M2_mpy_sat_hl_s1:
case M2_mpy_sat_rnd_hl_s0:
case M2_mpy_sat_rnd_hl_s1:
case M2_mpyd_acc_hl_s0:
case M2_mpyd_acc_hl_s1:
case M2_mpyd_hl_s0:
case M2_mpyd_hl_s1:
case M2_mpyd_nac_hl_s0:
case M2_mpyd_nac_hl_s1:
case M2_mpyd_rnd_hl_s0:
case M2_mpyd_rnd_hl_s1:
case M2_mpyu_acc_hl_s0:
case M2_mpyu_acc_hl_s1:
case M2_mpyu_hl_s0:
case M2_mpyu_hl_s1:
case M2_mpyu_nac_hl_s0:
case M2_mpyu_nac_hl_s1:
case M2_mpyud_acc_hl_s0:
case M2_mpyud_acc_hl_s1:
case M2_mpyud_hl_s0:
case M2_mpyud_hl_s1:
case M2_mpyud_nac_hl_s0:
case M2_mpyud_nac_hl_s1:
if (OpN == 1) {
Bits.set(Begin+16, Begin+32);
return true;
}
if (OpN == 2) {
Bits.set(Begin, Begin+16);
return true;
}
break;
// Two register sources, used bits: R1[16-31], R2[16-31].
case A2_addh_h16_hh:
case A2_addh_h16_sat_hh:
case A2_combine_hh:
case A2_subh_h16_hh:
case A2_subh_h16_sat_hh:
case M2_mpy_acc_hh_s0:
case M2_mpy_acc_hh_s1:
case M2_mpy_acc_sat_hh_s0:
case M2_mpy_acc_sat_hh_s1:
case M2_mpy_hh_s0:
case M2_mpy_hh_s1:
case M2_mpy_nac_hh_s0:
case M2_mpy_nac_hh_s1:
case M2_mpy_nac_sat_hh_s0:
case M2_mpy_nac_sat_hh_s1:
case M2_mpy_rnd_hh_s0:
case M2_mpy_rnd_hh_s1:
case M2_mpy_sat_hh_s0:
case M2_mpy_sat_hh_s1:
case M2_mpy_sat_rnd_hh_s0:
case M2_mpy_sat_rnd_hh_s1:
case M2_mpyd_acc_hh_s0:
case M2_mpyd_acc_hh_s1:
case M2_mpyd_hh_s0:
case M2_mpyd_hh_s1:
case M2_mpyd_nac_hh_s0:
case M2_mpyd_nac_hh_s1:
case M2_mpyd_rnd_hh_s0:
case M2_mpyd_rnd_hh_s1:
case M2_mpyu_acc_hh_s0:
case M2_mpyu_acc_hh_s1:
case M2_mpyu_hh_s0:
case M2_mpyu_hh_s1:
case M2_mpyu_nac_hh_s0:
case M2_mpyu_nac_hh_s1:
case M2_mpyud_acc_hh_s0:
case M2_mpyud_acc_hh_s1:
case M2_mpyud_hh_s0:
case M2_mpyud_hh_s1:
case M2_mpyud_nac_hh_s0:
case M2_mpyud_nac_hh_s1:
if (OpN == 1 || OpN == 2) {
Bits.set(Begin+16, Begin+32);
return true;
}
break;
}
return false;
}
// Calculate the register class that matches Reg:Sub. For example, if
// %1 is a double register, then %1:isub_hi would match the "int"
// register class.
const TargetRegisterClass *HexagonBitSimplify::getFinalVRegClass(
const BitTracker::RegisterRef &RR, MachineRegisterInfo &MRI) {
if (!TargetRegisterInfo::isVirtualRegister(RR.Reg))
return nullptr;
auto *RC = MRI.getRegClass(RR.Reg);
if (RR.Sub == 0)
return RC;
auto &HRI = static_cast<const HexagonRegisterInfo&>(
*MRI.getTargetRegisterInfo());
auto VerifySR = [&HRI] (const TargetRegisterClass *RC, unsigned Sub) -> void {
(void)HRI;
assert(Sub == HRI.getHexagonSubRegIndex(*RC, Hexagon::ps_sub_lo) ||
Sub == HRI.getHexagonSubRegIndex(*RC, Hexagon::ps_sub_hi));
};
switch (RC->getID()) {
case Hexagon::DoubleRegsRegClassID:
VerifySR(RC, RR.Sub);
return &Hexagon::IntRegsRegClass;
case Hexagon::HvxWRRegClassID:
VerifySR(RC, RR.Sub);
return &Hexagon::HvxVRRegClass;
}
return nullptr;
}
// Check if RD could be replaced with RS at any possible use of RD.
// For example a predicate register cannot be replaced with a integer
// register, but a 64-bit register with a subregister can be replaced
// with a 32-bit register.
bool HexagonBitSimplify::isTransparentCopy(const BitTracker::RegisterRef &RD,
const BitTracker::RegisterRef &RS, MachineRegisterInfo &MRI) {
if (!TargetRegisterInfo::isVirtualRegister(RD.Reg) ||
!TargetRegisterInfo::isVirtualRegister(RS.Reg))
return false;
// Return false if one (or both) classes are nullptr.
auto *DRC = getFinalVRegClass(RD, MRI);
if (!DRC)
return false;
return DRC == getFinalVRegClass(RS, MRI);
}
bool HexagonBitSimplify::hasTiedUse(unsigned Reg, MachineRegisterInfo &MRI,
unsigned NewSub) {
if (!PreserveTiedOps)
return false;
return llvm::any_of(MRI.use_operands(Reg),
[NewSub] (const MachineOperand &Op) -> bool {
return Op.getSubReg() != NewSub && Op.isTied();
});
}
namespace {
class DeadCodeElimination {
public:
DeadCodeElimination(MachineFunction &mf, MachineDominatorTree &mdt)
: MF(mf), HII(*MF.getSubtarget<HexagonSubtarget>().getInstrInfo()),
MDT(mdt), MRI(mf.getRegInfo()) {}
bool run() {
return runOnNode(MDT.getRootNode());
}
private:
bool isDead(unsigned R) const;
bool runOnNode(MachineDomTreeNode *N);
MachineFunction &MF;
const HexagonInstrInfo &HII;
MachineDominatorTree &MDT;
MachineRegisterInfo &MRI;
};
} // end anonymous namespace
bool DeadCodeElimination::isDead(unsigned R) const {
for (auto I = MRI.use_begin(R), E = MRI.use_end(); I != E; ++I) {
MachineInstr *UseI = I->getParent();
if (UseI->isDebugValue())
continue;
if (UseI->isPHI()) {
assert(!UseI->getOperand(0).getSubReg());
unsigned DR = UseI->getOperand(0).getReg();
if (DR == R)
continue;
}
return false;
}
return true;
}
bool DeadCodeElimination::runOnNode(MachineDomTreeNode *N) {
bool Changed = false;
for (auto *DTN : children<MachineDomTreeNode*>(N))
Changed |= runOnNode(DTN);
MachineBasicBlock *B = N->getBlock();
std::vector<MachineInstr*> Instrs;
for (auto I = B->rbegin(), E = B->rend(); I != E; ++I)
Instrs.push_back(&*I);
for (auto MI : Instrs) {
unsigned Opc = MI->getOpcode();
// Do not touch lifetime markers. This is why the target-independent DCE
// cannot be used.
if (Opc == TargetOpcode::LIFETIME_START ||
Opc == TargetOpcode::LIFETIME_END)
continue;
bool Store = false;
if (MI->isInlineAsm())
continue;
// Delete PHIs if possible.
if (!MI->isPHI() && !MI->isSafeToMove(nullptr, Store))
continue;
bool AllDead = true;
SmallVector<unsigned,2> Regs;
for (auto &Op : MI->operands()) {
if (!Op.isReg() || !Op.isDef())
continue;
unsigned R = Op.getReg();
if (!TargetRegisterInfo::isVirtualRegister(R) || !isDead(R)) {
AllDead = false;
break;
}
Regs.push_back(R);
}
if (!AllDead)
continue;
B->erase(MI);
for (unsigned i = 0, n = Regs.size(); i != n; ++i)
MRI.markUsesInDebugValueAsUndef(Regs[i]);
Changed = true;
}
return Changed;
}
namespace {
// Eliminate redundant instructions
//
// This transformation will identify instructions where the output register
// is the same as one of its input registers. This only works on instructions
// that define a single register (unlike post-increment loads, for example).
// The equality check is actually more detailed: the code calculates which
// bits of the output are used, and only compares these bits with the input
// registers.
// If the output matches an input, the instruction is replaced with COPY.
// The copies will be removed by another transformation.
class RedundantInstrElimination : public Transformation {
public:
RedundantInstrElimination(BitTracker &bt, const HexagonInstrInfo &hii,
const HexagonRegisterInfo &hri, MachineRegisterInfo &mri)
: Transformation(true), HII(hii), HRI(hri), MRI(mri), BT(bt) {}
bool processBlock(MachineBasicBlock &B, const RegisterSet &AVs) override;
private:
bool isLossyShiftLeft(const MachineInstr &MI, unsigned OpN,
unsigned &LostB, unsigned &LostE);
bool isLossyShiftRight(const MachineInstr &MI, unsigned OpN,
unsigned &LostB, unsigned &LostE);
bool computeUsedBits(unsigned Reg, BitVector &Bits);
bool computeUsedBits(const MachineInstr &MI, unsigned OpN, BitVector &Bits,
uint16_t Begin);
bool usedBitsEqual(BitTracker::RegisterRef RD, BitTracker::RegisterRef RS);
const HexagonInstrInfo &HII;
const HexagonRegisterInfo &HRI;
MachineRegisterInfo &MRI;
BitTracker &BT;
};
} // end anonymous namespace
// Check if the instruction is a lossy shift left, where the input being
// shifted is the operand OpN of MI. If true, [LostB, LostE) is the range
// of bit indices that are lost.
bool RedundantInstrElimination::isLossyShiftLeft(const MachineInstr &MI,
unsigned OpN, unsigned &LostB, unsigned &LostE) {
using namespace Hexagon;
unsigned Opc = MI.getOpcode();
unsigned ImN, RegN, Width;
switch (Opc) {
case S2_asl_i_p:
ImN = 2;
RegN = 1;
Width = 64;
break;
case S2_asl_i_p_acc:
case S2_asl_i_p_and:
case S2_asl_i_p_nac:
case S2_asl_i_p_or:
case S2_asl_i_p_xacc:
ImN = 3;
RegN = 2;
Width = 64;
break;
case S2_asl_i_r:
ImN = 2;
RegN = 1;
Width = 32;
break;
case S2_addasl_rrri:
case S4_andi_asl_ri:
case S4_ori_asl_ri:
case S4_addi_asl_ri:
case S4_subi_asl_ri:
case S2_asl_i_r_acc:
case S2_asl_i_r_and:
case S2_asl_i_r_nac:
case S2_asl_i_r_or:
case S2_asl_i_r_sat:
case S2_asl_i_r_xacc:
ImN = 3;
RegN = 2;
Width = 32;
break;
default:
return false;
}
if (RegN != OpN)
return false;
assert(MI.getOperand(ImN).isImm());
unsigned S = MI.getOperand(ImN).getImm();
if (S == 0)
return false;
LostB = Width-S;
LostE = Width;
return true;
}
// Check if the instruction is a lossy shift right, where the input being
// shifted is the operand OpN of MI. If true, [LostB, LostE) is the range
// of bit indices that are lost.
bool RedundantInstrElimination::isLossyShiftRight(const MachineInstr &MI,
unsigned OpN, unsigned &LostB, unsigned &LostE) {
using namespace Hexagon;
unsigned Opc = MI.getOpcode();
unsigned ImN, RegN;
switch (Opc) {
case S2_asr_i_p:
case S2_lsr_i_p:
ImN = 2;
RegN = 1;
break;
case S2_asr_i_p_acc:
case S2_asr_i_p_and:
case S2_asr_i_p_nac:
case S2_asr_i_p_or:
case S2_lsr_i_p_acc:
case S2_lsr_i_p_and:
case S2_lsr_i_p_nac:
case S2_lsr_i_p_or:
case S2_lsr_i_p_xacc:
ImN = 3;
RegN = 2;
break;
case S2_asr_i_r:
case S2_lsr_i_r:
ImN = 2;
RegN = 1;
break;
case S4_andi_lsr_ri:
case S4_ori_lsr_ri:
case S4_addi_lsr_ri:
case S4_subi_lsr_ri:
case S2_asr_i_r_acc:
case S2_asr_i_r_and:
case S2_asr_i_r_nac:
case S2_asr_i_r_or:
case S2_lsr_i_r_acc:
case S2_lsr_i_r_and:
case S2_lsr_i_r_nac:
case S2_lsr_i_r_or:
case S2_lsr_i_r_xacc:
ImN = 3;
RegN = 2;
break;
default:
return false;
}
if (RegN != OpN)
return false;
assert(MI.getOperand(ImN).isImm());
unsigned S = MI.getOperand(ImN).getImm();
LostB = 0;
LostE = S;
return true;
}
// Calculate the bit vector that corresponds to the used bits of register Reg.
// The vector Bits has the same size, as the size of Reg in bits. If the cal-
// culation fails (i.e. the used bits are unknown), it returns false. Other-
// wise, it returns true and sets the corresponding bits in Bits.
bool RedundantInstrElimination::computeUsedBits(unsigned Reg, BitVector &Bits) {
BitVector Used(Bits.size());
RegisterSet Visited;
std::vector<unsigned> Pending;
Pending.push_back(Reg);
for (unsigned i = 0; i < Pending.size(); ++i) {
unsigned R = Pending[i];
if (Visited.has(R))
continue;
Visited.insert(R);
for (auto I = MRI.use_begin(R), E = MRI.use_end(); I != E; ++I) {
BitTracker::RegisterRef UR = *I;
unsigned B, W;
if (!HBS::getSubregMask(UR, B, W, MRI))
return false;
MachineInstr &UseI = *I->getParent();
if (UseI.isPHI() || UseI.isCopy()) {
unsigned DefR = UseI.getOperand(0).getReg();
if (!TargetRegisterInfo::isVirtualRegister(DefR))
return false;
Pending.push_back(DefR);
} else {
if (!computeUsedBits(UseI, I.getOperandNo(), Used, B))
return false;
}
}
}
Bits |= Used;
return true;
}
// Calculate the bits used by instruction MI in a register in operand OpN.
// Return true/false if the calculation succeeds/fails. If is succeeds, set
// used bits in Bits. This function does not reset any bits in Bits, so
// subsequent calls over different instructions will result in the union
// of the used bits in all these instructions.
// The register in question may be used with a sub-register, whereas Bits
// holds the bits for the entire register. To keep track of that, the
// argument Begin indicates where in Bits is the lowest-significant bit
// of the register used in operand OpN. For example, in instruction:
// %1 = S2_lsr_i_r %2:isub_hi, 10
// the operand 1 is a 32-bit register, which happens to be a subregister
// of the 64-bit register %2, and that subregister starts at position 32.
// In this case Begin=32, since Bits[32] would be the lowest-significant bit
// of %2:isub_hi.
bool RedundantInstrElimination::computeUsedBits(const MachineInstr &MI,
unsigned OpN, BitVector &Bits, uint16_t Begin) {
unsigned Opc = MI.getOpcode();
BitVector T(Bits.size());
bool GotBits = HBS::getUsedBits(Opc, OpN, T, Begin, HII);
// Even if we don't have bits yet, we could still provide some information
// if the instruction is a lossy shift: the lost bits will be marked as
// not used.
unsigned LB, LE;
if (isLossyShiftLeft(MI, OpN, LB, LE) || isLossyShiftRight(MI, OpN, LB, LE)) {
assert(MI.getOperand(OpN).isReg());
BitTracker::RegisterRef RR = MI.getOperand(OpN);
const TargetRegisterClass *RC = HBS::getFinalVRegClass(RR, MRI);
uint16_t Width = HRI.getRegSizeInBits(*RC);
if (!GotBits)
T.set(Begin, Begin+Width);
assert(LB <= LE && LB < Width && LE <= Width);
T.reset(Begin+LB, Begin+LE);
GotBits = true;
}
if (GotBits)
Bits |= T;
return GotBits;
}
// Calculates the used bits in RD ("defined register"), and checks if these
// bits in RS ("used register") and RD are identical.
bool RedundantInstrElimination::usedBitsEqual(BitTracker::RegisterRef RD,
BitTracker::RegisterRef RS) {
const BitTracker::RegisterCell &DC = BT.lookup(RD.Reg);
const BitTracker::RegisterCell &SC = BT.lookup(RS.Reg);
unsigned DB, DW;
if (!HBS::getSubregMask(RD, DB, DW, MRI))
return false;
unsigned SB, SW;
if (!HBS::getSubregMask(RS, SB, SW, MRI))
return false;
if (SW != DW)
return false;
BitVector Used(DC.width());
if (!computeUsedBits(RD.Reg, Used))
return false;
for (unsigned i = 0; i != DW; ++i)
if (Used[i+DB] && DC[DB+i] != SC[SB+i])
return false;
return true;
}
bool RedundantInstrElimination::processBlock(MachineBasicBlock &B,
const RegisterSet&) {
if (!BT.reached(&B))
return false;
bool Changed = false;
for (auto I = B.begin(), E = B.end(), NextI = I; I != E; ++I) {
NextI = std::next(I);
MachineInstr *MI = &*I;
if (MI->getOpcode() == TargetOpcode::COPY)
continue;
if (MI->isPHI() || MI->hasUnmodeledSideEffects() || MI->isInlineAsm())
continue;
unsigned NumD = MI->getDesc().getNumDefs();
if (NumD != 1)
continue;
BitTracker::RegisterRef RD = MI->getOperand(0);
if (!BT.has(RD.Reg))
continue;
const BitTracker::RegisterCell &DC = BT.lookup(RD.Reg);
auto At = MachineBasicBlock::iterator(MI);
// Find a source operand that is equal to the result.
for (auto &Op : MI->uses()) {
if (!Op.isReg())
continue;
BitTracker::RegisterRef RS = Op;
if (!BT.has(RS.Reg))
continue;
if (!HBS::isTransparentCopy(RD, RS, MRI))
continue;
unsigned BN, BW;
if (!HBS::getSubregMask(RS, BN, BW, MRI))
continue;
const BitTracker::RegisterCell &SC = BT.lookup(RS.Reg);
if (!usedBitsEqual(RD, RS) && !HBS::isEqual(DC, 0, SC, BN, BW))
continue;
// If found, replace the instruction with a COPY.
const DebugLoc &DL = MI->getDebugLoc();
const TargetRegisterClass *FRC = HBS::getFinalVRegClass(RD, MRI);
unsigned NewR = MRI.createVirtualRegister(FRC);
MachineInstr *CopyI =
BuildMI(B, At, DL, HII.get(TargetOpcode::COPY), NewR)
.addReg(RS.Reg, 0, RS.Sub);
HBS::replaceSubWithSub(RD.Reg, RD.Sub, NewR, 0, MRI);
// This pass can create copies between registers that don't have the
// exact same values. Updating the tracker has to involve updating
// all dependent cells. Example:
// %1 = inst %2 ; %1 != %2, but used bits are equal
//
// %3 = copy %2 ; <- inserted
// ... = %3 ; <- replaced from %2
// Indirectly, we can create a "copy" between %1 and %2 even
// though their exact values do not match.
BT.visit(*CopyI);
Changed = true;
break;
}
}
return Changed;
}
namespace {
// Recognize instructions that produce constant values known at compile-time.
// Replace them with register definitions that load these constants directly.
class ConstGeneration : public Transformation {
public:
ConstGeneration(BitTracker &bt, const HexagonInstrInfo &hii,
MachineRegisterInfo &mri)
: Transformation(true), HII(hii), MRI(mri), BT(bt) {}
bool processBlock(MachineBasicBlock &B, const RegisterSet &AVs) override;
static bool isTfrConst(const MachineInstr &MI);
private:
unsigned genTfrConst(const TargetRegisterClass *RC, int64_t C,
MachineBasicBlock &B, MachineBasicBlock::iterator At, DebugLoc &DL);
const HexagonInstrInfo &HII;
MachineRegisterInfo &MRI;
BitTracker &BT;
};
} // end anonymous namespace
bool ConstGeneration::isTfrConst(const MachineInstr &MI) {
unsigned Opc = MI.getOpcode();
switch (Opc) {
case Hexagon::A2_combineii:
case Hexagon::A4_combineii:
case Hexagon::A2_tfrsi:
case Hexagon::A2_tfrpi:
case Hexagon::PS_true:
case Hexagon::PS_false:
case Hexagon::CONST32:
case Hexagon::CONST64:
return true;
}
return false;
}
// Generate a transfer-immediate instruction that is appropriate for the
// register class and the actual value being transferred.
unsigned ConstGeneration::genTfrConst(const TargetRegisterClass *RC, int64_t C,
MachineBasicBlock &B, MachineBasicBlock::iterator At, DebugLoc &DL) {
unsigned Reg = MRI.createVirtualRegister(RC);
if (RC == &Hexagon::IntRegsRegClass) {
BuildMI(B, At, DL, HII.get(Hexagon::A2_tfrsi), Reg)
.addImm(int32_t(C));
return Reg;
}
if (RC == &Hexagon::DoubleRegsRegClass) {
if (isInt<8>(C)) {
BuildMI(B, At, DL, HII.get(Hexagon::A2_tfrpi), Reg)
.addImm(C);
return Reg;
}
unsigned Lo = Lo_32(C), Hi = Hi_32(C);
if (isInt<8>(Lo) || isInt<8>(Hi)) {
unsigned Opc = isInt<8>(Lo) ? Hexagon::A2_combineii
: Hexagon::A4_combineii;
BuildMI(B, At, DL, HII.get(Opc), Reg)
.addImm(int32_t(Hi))
.addImm(int32_t(Lo));
return Reg;
}
BuildMI(B, At, DL, HII.get(Hexagon::CONST64), Reg)
.addImm(C);
return Reg;
}
if (RC == &Hexagon::PredRegsRegClass) {
unsigned Opc;
if (C == 0)
Opc = Hexagon::PS_false;
else if ((C & 0xFF) == 0xFF)
Opc = Hexagon::PS_true;
else
return 0;
BuildMI(B, At, DL, HII.get(Opc), Reg);
return Reg;
}
return 0;
}
bool ConstGeneration::processBlock(MachineBasicBlock &B, const RegisterSet&) {
if (!BT.reached(&B))
return false;
bool Changed = false;
RegisterSet Defs;
for (auto I = B.begin(), E = B.end(); I != E; ++I) {
if (isTfrConst(*I))
continue;
Defs.clear();
HBS::getInstrDefs(*I, Defs);
if (Defs.count() != 1)
continue;
unsigned DR = Defs.find_first();
if (!TargetRegisterInfo::isVirtualRegister(DR))
continue;
uint64_t U;
const BitTracker::RegisterCell &DRC = BT.lookup(DR);
if (HBS::getConst(DRC, 0, DRC.width(), U)) {
int64_t C = U;
DebugLoc DL = I->getDebugLoc();
auto At = I->isPHI() ? B.getFirstNonPHI() : I;
unsigned ImmReg = genTfrConst(MRI.getRegClass(DR), C, B, At, DL);
if (ImmReg) {
HBS::replaceReg(DR, ImmReg, MRI);
BT.put(ImmReg, DRC);
Changed = true;
}
}
}
return Changed;
}
namespace {
// Identify pairs of available registers which hold identical values.
// In such cases, only one of them needs to be calculated, the other one
// will be defined as a copy of the first.
class CopyGeneration : public Transformation {
public:
CopyGeneration(BitTracker &bt, const HexagonInstrInfo &hii,
const HexagonRegisterInfo &hri, MachineRegisterInfo &mri)
: Transformation(true), HII(hii), HRI(hri), MRI(mri), BT(bt) {}
bool processBlock(MachineBasicBlock &B, const RegisterSet &AVs) override;
private:
bool findMatch(const BitTracker::RegisterRef &Inp,
BitTracker::RegisterRef &Out, const RegisterSet &AVs);
const HexagonInstrInfo &HII;
const HexagonRegisterInfo &HRI;
MachineRegisterInfo &MRI;
BitTracker &BT;
RegisterSet Forbidden;
};
// Eliminate register copies RD = RS, by replacing the uses of RD with
// with uses of RS.
class CopyPropagation : public Transformation {
public:
CopyPropagation(const HexagonRegisterInfo &hri, MachineRegisterInfo &mri)
: Transformation(false), HRI(hri), MRI(mri) {}
bool processBlock(MachineBasicBlock &B, const RegisterSet &AVs) override;
static bool isCopyReg(unsigned Opc, bool NoConv);
private:
bool propagateRegCopy(MachineInstr &MI);
const HexagonRegisterInfo &HRI;
MachineRegisterInfo &MRI;
};
} // end anonymous namespace
/// Check if there is a register in AVs that is identical to Inp. If so,
/// set Out to the found register. The output may be a pair Reg:Sub.
bool CopyGeneration::findMatch(const BitTracker::RegisterRef &Inp,
BitTracker::RegisterRef &Out, const RegisterSet &AVs) {
if (!BT.has(Inp.Reg))
return false;
const BitTracker::RegisterCell &InpRC = BT.lookup(Inp.Reg);
auto *FRC = HBS::getFinalVRegClass(Inp, MRI);
unsigned B, W;
if (!HBS::getSubregMask(Inp, B, W, MRI))
return false;
for (unsigned R = AVs.find_first(); R; R = AVs.find_next(R)) {
if (!BT.has(R) || Forbidden[R])
continue;
const BitTracker::RegisterCell &RC = BT.lookup(R);
unsigned RW = RC.width();
if (W == RW) {
if (FRC != MRI.getRegClass(R))
continue;
if (!HBS::isTransparentCopy(R, Inp, MRI))
continue;
if (!HBS::isEqual(InpRC, B, RC, 0, W))
continue;
Out.Reg = R;
Out.Sub = 0;
return true;
}
// Check if there is a super-register, whose part (with a subregister)
// is equal to the input.
// Only do double registers for now.
if (W*2 != RW)
continue;
if (MRI.getRegClass(R) != &Hexagon::DoubleRegsRegClass)
continue;
if (HBS::isEqual(InpRC, B, RC, 0, W))
Out.Sub = Hexagon::isub_lo;
else if (HBS::isEqual(InpRC, B, RC, W, W))
Out.Sub = Hexagon::isub_hi;
else
continue;
Out.Reg = R;
if (HBS::isTransparentCopy(Out, Inp, MRI))
return true;
}
return false;
}
bool CopyGeneration::processBlock(MachineBasicBlock &B,
const RegisterSet &AVs) {
if (!BT.reached(&B))
return false;
RegisterSet AVB(AVs);
bool Changed = false;
RegisterSet Defs;
for (auto I = B.begin(), E = B.end(), NextI = I; I != E;
++I, AVB.insert(Defs)) {
NextI = std::next(I);
Defs.clear();
HBS::getInstrDefs(*I, Defs);
unsigned Opc = I->getOpcode();
if (CopyPropagation::isCopyReg(Opc, false) ||
ConstGeneration::isTfrConst(*I))
continue;
DebugLoc DL = I->getDebugLoc();
auto At = I->isPHI() ? B.getFirstNonPHI() : I;
for (unsigned R = Defs.find_first(); R; R = Defs.find_next(R)) {
BitTracker::RegisterRef MR;
auto *FRC = HBS::getFinalVRegClass(R, MRI);
if (findMatch(R, MR, AVB)) {
unsigned NewR = MRI.createVirtualRegister(FRC);
BuildMI(B, At, DL, HII.get(TargetOpcode::COPY), NewR)
.addReg(MR.Reg, 0, MR.Sub);
BT.put(BitTracker::RegisterRef(NewR), BT.get(MR));
HBS::replaceReg(R, NewR, MRI);
Forbidden.insert(R);
continue;
}
if (FRC == &Hexagon::DoubleRegsRegClass ||
FRC == &Hexagon::HvxWRRegClass) {
// Try to generate REG_SEQUENCE.
unsigned SubLo = HRI.getHexagonSubRegIndex(*FRC, Hexagon::ps_sub_lo);
unsigned SubHi = HRI.getHexagonSubRegIndex(*FRC, Hexagon::ps_sub_hi);
BitTracker::RegisterRef TL = { R, SubLo };
BitTracker::RegisterRef TH = { R, SubHi };
BitTracker::RegisterRef ML, MH;
if (findMatch(TL, ML, AVB) && findMatch(TH, MH, AVB)) {
auto *FRC = HBS::getFinalVRegClass(R, MRI);
unsigned NewR = MRI.createVirtualRegister(FRC);
BuildMI(B, At, DL, HII.get(TargetOpcode::REG_SEQUENCE), NewR)
.addReg(ML.Reg, 0, ML.Sub)
.addImm(SubLo)
.addReg(MH.Reg, 0, MH.Sub)
.addImm(SubHi);
BT.put(BitTracker::RegisterRef(NewR), BT.get(R));
HBS::replaceReg(R, NewR, MRI);
Forbidden.insert(R);
}
}
}
}
return Changed;
}
bool CopyPropagation::isCopyReg(unsigned Opc, bool NoConv) {
switch (Opc) {
case TargetOpcode::COPY:
case TargetOpcode::REG_SEQUENCE:
case Hexagon::A4_combineir:
case Hexagon::A4_combineri:
return true;
case Hexagon::A2_tfr:
case Hexagon::A2_tfrp:
case Hexagon::A2_combinew:
case Hexagon::V6_vcombine:
return NoConv;
default:
break;
}
return false;
}
bool CopyPropagation::propagateRegCopy(MachineInstr &MI) {
bool Changed = false;
unsigned Opc = MI.getOpcode();
BitTracker::RegisterRef RD = MI.getOperand(0);
assert(MI.getOperand(0).getSubReg() == 0);
switch (Opc) {
case TargetOpcode::COPY:
case Hexagon::A2_tfr:
case Hexagon::A2_tfrp: {
BitTracker::RegisterRef RS = MI.getOperand(1);
if (!HBS::isTransparentCopy(RD, RS, MRI))
break;
if (RS.Sub != 0)
Changed = HBS::replaceRegWithSub(RD.Reg, RS.Reg, RS.Sub, MRI);
else
Changed = HBS::replaceReg(RD.Reg, RS.Reg, MRI);
break;
}
case TargetOpcode::REG_SEQUENCE: {
BitTracker::RegisterRef SL, SH;
if (HBS::parseRegSequence(MI, SL, SH, MRI)) {
const TargetRegisterClass &RC = *MRI.getRegClass(RD.Reg);
unsigned SubLo = HRI.getHexagonSubRegIndex(RC, Hexagon::ps_sub_lo);
unsigned SubHi = HRI.getHexagonSubRegIndex(RC, Hexagon::ps_sub_hi);
Changed = HBS::replaceSubWithSub(RD.Reg, SubLo, SL.Reg, SL.Sub, MRI);
Changed |= HBS::replaceSubWithSub(RD.Reg, SubHi, SH.Reg, SH.Sub, MRI);
}
break;
}
case Hexagon::A2_combinew:
case Hexagon::V6_vcombine: {
const TargetRegisterClass &RC = *MRI.getRegClass(RD.Reg);
unsigned SubLo = HRI.getHexagonSubRegIndex(RC, Hexagon::ps_sub_lo);
unsigned SubHi = HRI.getHexagonSubRegIndex(RC, Hexagon::ps_sub_hi);
BitTracker::RegisterRef RH = MI.getOperand(1), RL = MI.getOperand(2);
Changed = HBS::replaceSubWithSub(RD.Reg, SubLo, RL.Reg, RL.Sub, MRI);
Changed |= HBS::replaceSubWithSub(RD.Reg, SubHi, RH.Reg, RH.Sub, MRI);
break;
}
case Hexagon::A4_combineir:
case Hexagon::A4_combineri: {
unsigned SrcX = (Opc == Hexagon::A4_combineir) ? 2 : 1;
unsigned Sub = (Opc == Hexagon::A4_combineir) ? Hexagon::isub_lo
: Hexagon::isub_hi;
BitTracker::RegisterRef RS = MI.getOperand(SrcX);
Changed = HBS::replaceSubWithSub(RD.Reg, Sub, RS.Reg, RS.Sub, MRI);
break;
}
}
return Changed;
}
bool CopyPropagation::processBlock(MachineBasicBlock &B, const RegisterSet&) {
std::vector<MachineInstr*> Instrs;
for (auto I = B.rbegin(), E = B.rend(); I != E; ++I)
Instrs.push_back(&*I);
bool Changed = false;
for (auto I : Instrs) {
unsigned Opc = I->getOpcode();
if (!CopyPropagation::isCopyReg(Opc, true))
continue;
Changed |= propagateRegCopy(*I);
}
return Changed;
}
namespace {
// Recognize patterns that can be simplified and replace them with the
// simpler forms.
// This is by no means complete
class BitSimplification : public Transformation {
public:
BitSimplification(BitTracker &bt, const MachineDominatorTree &mdt,
const HexagonInstrInfo &hii, const HexagonRegisterInfo &hri,
MachineRegisterInfo &mri, MachineFunction &mf)
: Transformation(true), MDT(mdt), HII(hii), HRI(hri), MRI(mri),
MF(mf), BT(bt) {}
bool processBlock(MachineBasicBlock &B, const RegisterSet &AVs) override;
private:
struct RegHalf : public BitTracker::RegisterRef {
bool Low; // Low/High halfword.
};
bool matchHalf(unsigned SelfR, const BitTracker::RegisterCell &RC,
unsigned B, RegHalf &RH);
bool validateReg(BitTracker::RegisterRef R, unsigned Opc, unsigned OpNum);
bool matchPackhl(unsigned SelfR, const BitTracker::RegisterCell &RC,
BitTracker::RegisterRef &Rs, BitTracker::RegisterRef &Rt);
unsigned getCombineOpcode(bool HLow, bool LLow);
bool genStoreUpperHalf(MachineInstr *MI);
bool genStoreImmediate(MachineInstr *MI);
bool genPackhl(MachineInstr *MI, BitTracker::RegisterRef RD,
const BitTracker::RegisterCell &RC);
bool genExtractHalf(MachineInstr *MI, BitTracker::RegisterRef RD,
const BitTracker::RegisterCell &RC);
bool genCombineHalf(MachineInstr *MI, BitTracker::RegisterRef RD,
const BitTracker::RegisterCell &RC);
bool genExtractLow(MachineInstr *MI, BitTracker::RegisterRef RD,
const BitTracker::RegisterCell &RC);
bool genBitSplit(MachineInstr *MI, BitTracker::RegisterRef RD,
const BitTracker::RegisterCell &RC, const RegisterSet &AVs);
bool simplifyTstbit(MachineInstr *MI, BitTracker::RegisterRef RD,
const BitTracker::RegisterCell &RC);
bool simplifyExtractLow(MachineInstr *MI, BitTracker::RegisterRef RD,
const BitTracker::RegisterCell &RC, const RegisterSet &AVs);
bool simplifyRCmp0(MachineInstr *MI, BitTracker::RegisterRef RD);
// Cache of created instructions to avoid creating duplicates.
// XXX Currently only used by genBitSplit.
std::vector<MachineInstr*> NewMIs;
const MachineDominatorTree &MDT;
const HexagonInstrInfo &HII;
const HexagonRegisterInfo &HRI;
MachineRegisterInfo &MRI;
MachineFunction &MF;
BitTracker &BT;
};
} // end anonymous namespace
// Check if the bits [B..B+16) in register cell RC form a valid halfword,
// i.e. [0..16), [16..32), etc. of some register. If so, return true and
// set the information about the found register in RH.
bool BitSimplification::matchHalf(unsigned SelfR,
const BitTracker::RegisterCell &RC, unsigned B, RegHalf &RH) {
// XXX This could be searching in the set of available registers, in case
// the match is not exact.
// Match 16-bit chunks, where the RC[B..B+15] references exactly one
// register and all the bits B..B+15 match between RC and the register.
// This is meant to match "v1[0-15]", where v1 = { [0]:0 [1-15]:v1... },
// and RC = { [0]:0 [1-15]:v1[1-15]... }.
bool Low = false;
unsigned I = B;
while (I < B+16 && RC[I].num())
I++;
if (I == B+16)
return false;
unsigned Reg = RC[I].RefI.Reg;
unsigned P = RC[I].RefI.Pos; // The RefI.Pos will be advanced by I-B.
if (P < I-B)
return false;
unsigned Pos = P - (I-B);
if (Reg == 0 || Reg == SelfR) // Don't match "self".
return false;
if (!TargetRegisterInfo::isVirtualRegister(Reg))
return false;
if (!BT.has(Reg))
return false;
const BitTracker::RegisterCell &SC = BT.lookup(Reg);
if (Pos+16 > SC.width())
return false;
for (unsigned i = 0; i < 16; ++i) {
const BitTracker::BitValue &RV = RC[i+B];
if (RV.Type == BitTracker::BitValue::Ref) {
if (RV.RefI.Reg != Reg)
return false;
if (RV.RefI.Pos != i+Pos)
return false;
continue;
}
if (RC[i+B] != SC[i+Pos])
return false;
}
unsigned Sub = 0;
switch (Pos) {
case 0:
Sub = Hexagon::isub_lo;
Low = true;
break;
case 16:
Sub = Hexagon::isub_lo;
Low = false;
break;
case 32:
Sub = Hexagon::isub_hi;
Low = true;
break;
case 48:
Sub = Hexagon::isub_hi;
Low = false;
break;
default:
return false;
}
RH.Reg = Reg;
RH.Sub = Sub;
RH.Low = Low;
// If the subregister is not valid with the register, set it to 0.
if (!HBS::getFinalVRegClass(RH, MRI))
RH.Sub = 0;
return true;
}
bool BitSimplification::validateReg(BitTracker::RegisterRef R, unsigned Opc,
unsigned OpNum) {
auto *OpRC = HII.getRegClass(HII.get(Opc), OpNum, &HRI, MF);
auto *RRC = HBS::getFinalVRegClass(R, MRI);
return OpRC->hasSubClassEq(RRC);
}
// Check if RC matches the pattern of a S2_packhl. If so, return true and
// set the inputs Rs and Rt.
bool BitSimplification::matchPackhl(unsigned SelfR,
const BitTracker::RegisterCell &RC, BitTracker::RegisterRef &Rs,
BitTracker::RegisterRef &Rt) {
RegHalf L1, H1, L2, H2;
if (!matchHalf(SelfR, RC, 0, L2) || !matchHalf(SelfR, RC, 16, L1))
return false;
if (!matchHalf(SelfR, RC, 32, H2) || !matchHalf(SelfR, RC, 48, H1))
return false;
// Rs = H1.L1, Rt = H2.L2
if (H1.Reg != L1.Reg || H1.Sub != L1.Sub || H1.Low || !L1.Low)
return false;
if (H2.Reg != L2.Reg || H2.Sub != L2.Sub || H2.Low || !L2.Low)
return false;
Rs = H1;
Rt = H2;
return true;
}
unsigned BitSimplification::getCombineOpcode(bool HLow, bool LLow) {
return HLow ? LLow ? Hexagon::A2_combine_ll
: Hexagon::A2_combine_lh
: LLow ? Hexagon::A2_combine_hl
: Hexagon::A2_combine_hh;
}
// If MI stores the upper halfword of a register (potentially obtained via
// shifts or extracts), replace it with a storerf instruction. This could
// cause the "extraction" code to become dead.
bool BitSimplification::genStoreUpperHalf(MachineInstr *MI) {
unsigned Opc = MI->getOpcode();
if (Opc != Hexagon::S2_storerh_io)
return false;
MachineOperand &ValOp = MI->getOperand(2);
BitTracker::RegisterRef RS = ValOp;
if (!BT.has(RS.Reg))
return false;
const BitTracker::RegisterCell &RC = BT.lookup(RS.Reg);
RegHalf H;
if (!matchHalf(0, RC, 0, H))
return false;
if (H.Low)
return false;
MI->setDesc(HII.get(Hexagon::S2_storerf_io));
ValOp.setReg(H.Reg);
ValOp.setSubReg(H.Sub);
return true;
}
// If MI stores a value known at compile-time, and the value is within a range
// that avoids using constant-extenders, replace it with a store-immediate.
bool BitSimplification::genStoreImmediate(MachineInstr *MI) {
unsigned Opc = MI->getOpcode();
unsigned Align = 0;
switch (Opc) {
case Hexagon::S2_storeri_io:
Align++;
LLVM_FALLTHROUGH;
case Hexagon::S2_storerh_io:
Align++;
LLVM_FALLTHROUGH;
case Hexagon::S2_storerb_io:
break;
default:
return false;
}
// Avoid stores to frame-indices (due to an unknown offset).
if (!MI->getOperand(0).isReg())
return false;
MachineOperand &OffOp = MI->getOperand(1);
if (!OffOp.isImm())
return false;
int64_t Off = OffOp.getImm();
// Offset is u6:a. Sadly, there is no isShiftedUInt(n,x).
if (!isUIntN(6+Align, Off) || (Off & ((1<<Align)-1)))
return false;
// Source register:
BitTracker::RegisterRef RS = MI->getOperand(2);
if (!BT.has(RS.Reg))
return false;
const BitTracker::RegisterCell &RC = BT.lookup(RS.Reg);
uint64_t U;
if (!HBS::getConst(RC, 0, RC.width(), U))
return false;
// Only consider 8-bit values to avoid constant-extenders.
int V;
switch (Opc) {
case Hexagon::S2_storerb_io:
V = int8_t(U);
break;
case Hexagon::S2_storerh_io:
V = int16_t(U);
break;
case Hexagon::S2_storeri_io:
V = int32_t(U);
break;
default:
// Opc is already checked above to be one of the three store instructions.
// This silences a -Wuninitialized false positive on GCC 5.4.
llvm_unreachable("Unexpected store opcode");
}
if (!isInt<8>(V))
return false;
MI->RemoveOperand(2);
switch (Opc) {
case Hexagon::S2_storerb_io:
MI->setDesc(HII.get(Hexagon::S4_storeirb_io));
break;
case Hexagon::S2_storerh_io:
MI->setDesc(HII.get(Hexagon::S4_storeirh_io));
break;
case Hexagon::S2_storeri_io:
MI->setDesc(HII.get(Hexagon::S4_storeiri_io));
break;
}
MI->addOperand(MachineOperand::CreateImm(V));
return true;
}
// If MI is equivalent o S2_packhl, generate the S2_packhl. MI could be the
// last instruction in a sequence that results in something equivalent to
// the pack-halfwords. The intent is to cause the entire sequence to become
// dead.
bool BitSimplification::genPackhl(MachineInstr *MI,
BitTracker::RegisterRef RD, const BitTracker::RegisterCell &RC) {
unsigned Opc = MI->getOpcode();
if (Opc == Hexagon::S2_packhl)
return false;
BitTracker::RegisterRef Rs, Rt;
if (!matchPackhl(RD.Reg, RC, Rs, Rt))
return false;
if (!validateReg(Rs, Hexagon::S2_packhl, 1) ||
!validateReg(Rt, Hexagon::S2_packhl, 2))
return false;
MachineBasicBlock &B = *MI->getParent();
unsigned NewR = MRI.createVirtualRegister(&Hexagon::DoubleRegsRegClass);
DebugLoc DL = MI->getDebugLoc();
auto At = MI->isPHI() ? B.getFirstNonPHI()
: MachineBasicBlock::iterator(MI);
BuildMI(B, At, DL, HII.get(Hexagon::S2_packhl), NewR)
.addReg(Rs.Reg, 0, Rs.Sub)
.addReg(Rt.Reg, 0, Rt.Sub);
HBS::replaceSubWithSub(RD.Reg, RD.Sub, NewR, 0, MRI);
BT.put(BitTracker::RegisterRef(NewR), RC);
return true;
}
// If MI produces halfword of the input in the low half of the output,
// replace it with zero-extend or extractu.
bool BitSimplification::genExtractHalf(MachineInstr *MI,
BitTracker::RegisterRef RD, const BitTracker::RegisterCell &RC) {
RegHalf L;
// Check for halfword in low 16 bits, zeros elsewhere.
if (!matchHalf(RD.Reg, RC, 0, L) || !HBS::isZero(RC, 16, 16))
return false;
unsigned Opc = MI->getOpcode();
MachineBasicBlock &B = *MI->getParent();
DebugLoc DL = MI->getDebugLoc();
// Prefer zxth, since zxth can go in any slot, while extractu only in
// slots 2 and 3.
unsigned NewR = 0;
auto At = MI->isPHI() ? B.getFirstNonPHI()
: MachineBasicBlock::iterator(MI);
if (L.Low && Opc != Hexagon::A2_zxth) {
if (validateReg(L, Hexagon::A2_zxth, 1)) {
NewR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
BuildMI(B, At, DL, HII.get(Hexagon::A2_zxth), NewR)
.addReg(L.Reg, 0, L.Sub);
}
} else if (!L.Low && Opc != Hexagon::S2_lsr_i_r) {
if (validateReg(L, Hexagon::S2_lsr_i_r, 1)) {
NewR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
BuildMI(B, MI, DL, HII.get(Hexagon::S2_lsr_i_r), NewR)
.addReg(L.Reg, 0, L.Sub)
.addImm(16);
}
}
if (NewR == 0)
return false;
HBS::replaceSubWithSub(RD.Reg, RD.Sub, NewR, 0, MRI);
BT.put(BitTracker::RegisterRef(NewR), RC);
return true;
}
// If MI is equivalent to a combine(.L/.H, .L/.H) replace with with the
// combine.
bool BitSimplification::genCombineHalf(MachineInstr *MI,
BitTracker::RegisterRef RD, const BitTracker::RegisterCell &RC) {
RegHalf L, H;
// Check for combine h/l
if (!matchHalf(RD.Reg, RC, 0, L) || !matchHalf(RD.Reg, RC, 16, H))
return false;
// Do nothing if this is just a reg copy.
if (L.Reg == H.Reg && L.Sub == H.Sub && !H.Low && L.Low)
return false;
unsigned Opc = MI->getOpcode();
unsigned COpc = getCombineOpcode(H.Low, L.Low);
if (COpc == Opc)
return false;
if (!validateReg(H, COpc, 1) || !validateReg(L, COpc, 2))
return false;
MachineBasicBlock &B = *MI->getParent();
DebugLoc DL = MI->getDebugLoc();
unsigned NewR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
auto At = MI->isPHI() ? B.getFirstNonPHI()
: MachineBasicBlock::iterator(MI);
BuildMI(B, At, DL, HII.get(COpc), NewR)
.addReg(H.Reg, 0, H.Sub)
.addReg(L.Reg, 0, L.Sub);
HBS::replaceSubWithSub(RD.Reg, RD.Sub, NewR, 0, MRI);
BT.put(BitTracker::RegisterRef(NewR), RC);
return true;
}
// If MI resets high bits of a register and keeps the lower ones, replace it
// with zero-extend byte/half, and-immediate, or extractu, as appropriate.
bool BitSimplification::genExtractLow(MachineInstr *MI,
BitTracker::RegisterRef RD, const BitTracker::RegisterCell &RC) {
unsigned Opc = MI->getOpcode();
switch (Opc) {
case Hexagon::A2_zxtb:
case Hexagon::A2_zxth:
case Hexagon::S2_extractu:
return false;
}
if (Opc == Hexagon::A2_andir && MI->getOperand(2).isImm()) {
int32_t Imm = MI->getOperand(2).getImm();
if (isInt<10>(Imm))
return false;
}
if (MI->hasUnmodeledSideEffects() || MI->isInlineAsm())
return false;
unsigned W = RC.width();
while (W > 0 && RC[W-1].is(0))
W--;
if (W == 0 || W == RC.width())
return false;
unsigned NewOpc = (W == 8) ? Hexagon::A2_zxtb
: (W == 16) ? Hexagon::A2_zxth
: (W < 10) ? Hexagon::A2_andir
: Hexagon::S2_extractu;
MachineBasicBlock &B = *MI->getParent();
DebugLoc DL = MI->getDebugLoc();
for (auto &Op : MI->uses()) {
if (!Op.isReg())
continue;
BitTracker::RegisterRef RS = Op;
if (!BT.has(RS.Reg))
continue;
const BitTracker::RegisterCell &SC = BT.lookup(RS.Reg);
unsigned BN, BW;
if (!HBS::getSubregMask(RS, BN, BW, MRI))
continue;
if (BW < W || !HBS::isEqual(RC, 0, SC, BN, W))
continue;
if (!validateReg(RS, NewOpc, 1))
continue;
unsigned NewR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
auto At = MI->isPHI() ? B.getFirstNonPHI()
: MachineBasicBlock::iterator(MI);
auto MIB = BuildMI(B, At, DL, HII.get(NewOpc), NewR)
.addReg(RS.Reg, 0, RS.Sub);
if (NewOpc == Hexagon::A2_andir)
MIB.addImm((1 << W) - 1);
else if (NewOpc == Hexagon::S2_extractu)
MIB.addImm(W).addImm(0);
HBS::replaceSubWithSub(RD.Reg, RD.Sub, NewR, 0, MRI);
BT.put(BitTracker::RegisterRef(NewR), RC);
return true;
}
return false;
}
bool BitSimplification::genBitSplit(MachineInstr *MI,
BitTracker::RegisterRef RD, const BitTracker::RegisterCell &RC,
const RegisterSet &AVs) {
if (!GenBitSplit)
return false;
if (MaxBitSplit.getNumOccurrences()) {
if (CountBitSplit >= MaxBitSplit)
return false;
}
unsigned Opc = MI->getOpcode();
switch (Opc) {
case Hexagon::A4_bitsplit:
case Hexagon::A4_bitspliti:
return false;
}
unsigned W = RC.width();
if (W != 32)
return false;
auto ctlz = [] (const BitTracker::RegisterCell &C) -> unsigned {
unsigned Z = C.width();
while (Z > 0 && C[Z-1].is(0))
--Z;
return C.width() - Z;
};
// Count the number of leading zeros in the target RC.
unsigned Z = ctlz(RC);
if (Z == 0 || Z == W)
return false;
// A simplistic analysis: assume the source register (the one being split)
// is fully unknown, and that all its bits are self-references.
const BitTracker::BitValue &B0 = RC[0];
if (B0.Type != BitTracker::BitValue::Ref)
return false;
unsigned SrcR = B0.RefI.Reg;
unsigned SrcSR = 0;
unsigned Pos = B0.RefI.Pos;
// All the non-zero bits should be consecutive bits from the same register.
for (unsigned i = 1; i < W-Z; ++i) {
const BitTracker::BitValue &V = RC[i];
if (V.Type != BitTracker::BitValue::Ref)
return false;
if (V.RefI.Reg != SrcR || V.RefI.Pos != Pos+i)
return false;
}
// Now, find the other bitfield among AVs.
for (unsigned S = AVs.find_first(); S; S = AVs.find_next(S)) {
// The number of leading zeros here should be the number of trailing
// non-zeros in RC.
unsigned SRC = MRI.getRegClass(S)->getID();
if (SRC != Hexagon::IntRegsRegClassID &&
SRC != Hexagon::DoubleRegsRegClassID)
continue;
if (!BT.has(S))
continue;
const BitTracker::RegisterCell &SC = BT.lookup(S);
if (SC.width() != W || ctlz(SC) != W-Z)
continue;
// The Z lower bits should now match SrcR.
const BitTracker::BitValue &S0 = SC[0];
if (S0.Type != BitTracker::BitValue::Ref || S0.RefI.Reg != SrcR)
continue;
unsigned P = S0.RefI.Pos;
if (Pos <= P && (Pos + W-Z) != P)
continue;
if (P < Pos && (P + Z) != Pos)
continue;
// The starting bitfield position must be at a subregister boundary.
if (std::min(P, Pos) != 0 && std::min(P, Pos) != 32)
continue;
unsigned I;
for (I = 1; I < Z; ++I) {
const BitTracker::BitValue &V = SC[I];
if (V.Type != BitTracker::BitValue::Ref)
break;
if (V.RefI.Reg != SrcR || V.RefI.Pos != P+I)
break;
}
if (I != Z)
continue;
// Generate bitsplit where S is defined.
if (MaxBitSplit.getNumOccurrences())
CountBitSplit++;
MachineInstr *DefS = MRI.getVRegDef(S);
assert(DefS != nullptr);
DebugLoc DL = DefS->getDebugLoc();
MachineBasicBlock &B = *DefS->getParent();
auto At = DefS->isPHI() ? B.getFirstNonPHI()
: MachineBasicBlock::iterator(DefS);
if (MRI.getRegClass(SrcR)->getID() == Hexagon::DoubleRegsRegClassID)
SrcSR = (std::min(Pos, P) == 32) ? Hexagon::isub_hi : Hexagon::isub_lo;
if (!validateReg({SrcR,SrcSR}, Hexagon::A4_bitspliti, 1))
continue;
unsigned ImmOp = Pos <= P ? W-Z : Z;
// Find an existing bitsplit instruction if one already exists.
unsigned NewR = 0;
for (MachineInstr *In : NewMIs) {
if (In->getOpcode() != Hexagon::A4_bitspliti)
continue;
MachineOperand &Op1 = In->getOperand(1);
if (Op1.getReg() != SrcR || Op1.getSubReg() != SrcSR)
continue;
if (In->getOperand(2).getImm() != ImmOp)
continue;
// Check if the target register is available here.
MachineOperand &Op0 = In->getOperand(0);
MachineInstr *DefI = MRI.getVRegDef(Op0.getReg());
assert(DefI != nullptr);
if (!MDT.dominates(DefI, &*At))
continue;
// Found one that can be reused.
assert(Op0.getSubReg() == 0);
NewR = Op0.getReg();
break;
}
if (!NewR) {
NewR = MRI.createVirtualRegister(&Hexagon::DoubleRegsRegClass);
auto NewBS = BuildMI(B, At, DL, HII.get(Hexagon::A4_bitspliti), NewR)
.addReg(SrcR, 0, SrcSR)
.addImm(ImmOp);
NewMIs.push_back(NewBS);
}
if (Pos <= P) {
HBS::replaceRegWithSub(RD.Reg, NewR, Hexagon::isub_lo, MRI);
HBS::replaceRegWithSub(S, NewR, Hexagon::isub_hi, MRI);
} else {
HBS::replaceRegWithSub(S, NewR, Hexagon::isub_lo, MRI);
HBS::replaceRegWithSub(RD.Reg, NewR, Hexagon::isub_hi, MRI);
}
return true;
}
return false;
}
// Check for tstbit simplification opportunity, where the bit being checked
// can be tracked back to another register. For example:
// %2 = S2_lsr_i_r %1, 5
// %3 = S2_tstbit_i %2, 0
// =>
// %3 = S2_tstbit_i %1, 5
bool BitSimplification::simplifyTstbit(MachineInstr *MI,
BitTracker::RegisterRef RD, const BitTracker::RegisterCell &RC) {
unsigned Opc = MI->getOpcode();
if (Opc != Hexagon::S2_tstbit_i)
return false;
unsigned BN = MI->getOperand(2).getImm();
BitTracker::RegisterRef RS = MI->getOperand(1);
unsigned F, W;
DebugLoc DL = MI->getDebugLoc();
if (!BT.has(RS.Reg) || !HBS::getSubregMask(RS, F, W, MRI))
return false;
MachineBasicBlock &B = *MI->getParent();
auto At = MI->isPHI() ? B.getFirstNonPHI()
: MachineBasicBlock::iterator(MI);
const BitTracker::RegisterCell &SC = BT.lookup(RS.Reg);
const BitTracker::BitValue &V = SC[F+BN];
if (V.Type == BitTracker::BitValue::Ref && V.RefI.Reg != RS.Reg) {
const TargetRegisterClass *TC = MRI.getRegClass(V.RefI.Reg);
// Need to map V.RefI.Reg to a 32-bit register, i.e. if it is
// a double register, need to use a subregister and adjust bit
// number.
unsigned P = std::numeric_limits<unsigned>::max();
BitTracker::RegisterRef RR(V.RefI.Reg, 0);
if (TC == &Hexagon::DoubleRegsRegClass) {
P = V.RefI.Pos;
RR.Sub = Hexagon::isub_lo;
if (P >= 32) {
P -= 32;
RR.Sub = Hexagon::isub_hi;
}
} else if (TC == &Hexagon::IntRegsRegClass) {
P = V.RefI.Pos;
}
if (P != std::numeric_limits<unsigned>::max()) {
unsigned NewR = MRI.createVirtualRegister(&Hexagon::PredRegsRegClass);
BuildMI(B, At, DL, HII.get(Hexagon::S2_tstbit_i), NewR)
.addReg(RR.Reg, 0, RR.Sub)
.addImm(P);
HBS::replaceReg(RD.Reg, NewR, MRI);
BT.put(NewR, RC);
return true;
}
} else if (V.is(0) || V.is(1)) {
unsigned NewR = MRI.createVirtualRegister(&Hexagon::PredRegsRegClass);
unsigned NewOpc = V.is(0) ? Hexagon::PS_false : Hexagon::PS_true;
BuildMI(B, At, DL, HII.get(NewOpc), NewR);
HBS::replaceReg(RD.Reg, NewR, MRI);
return true;
}
return false;
}
// Detect whether RD is a bitfield extract (sign- or zero-extended) of
// some register from the AVs set. Create a new corresponding instruction
// at the location of MI. The intent is to recognize situations where
// a sequence of instructions performs an operation that is equivalent to
// an extract operation, such as a shift left followed by a shift right.
bool BitSimplification::simplifyExtractLow(MachineInstr *MI,
BitTracker::RegisterRef RD, const BitTracker::RegisterCell &RC,
const RegisterSet &AVs) {
if (!GenExtract)
return false;
if (MaxExtract.getNumOccurrences()) {
if (CountExtract >= MaxExtract)
return false;
CountExtract++;
}
unsigned W = RC.width();
unsigned RW = W;
unsigned Len;
bool Signed;
// The code is mostly class-independent, except for the part that generates
// the extract instruction, and establishes the source register (in case it
// needs to use a subregister).
const TargetRegisterClass *FRC = HBS::getFinalVRegClass(RD, MRI);
if (FRC != &Hexagon::IntRegsRegClass && FRC != &Hexagon::DoubleRegsRegClass)
return false;
assert(RD.Sub == 0);
// Observation:
// If the cell has a form of 00..0xx..x with k zeros and n remaining
// bits, this could be an extractu of the n bits, but it could also be
// an extractu of a longer field which happens to have 0s in the top
// bit positions.
// The same logic applies to sign-extended fields.
//
// Do not check for the extended extracts, since it would expand the
// search space quite a bit. The search may be expensive as it is.
const BitTracker::BitValue &TopV = RC[W-1];
// Eliminate candidates that have self-referential bits, since they
// cannot be extracts from other registers. Also, skip registers that
// have compile-time constant values.
bool IsConst = true;
for (unsigned I = 0; I != W; ++I) {
const BitTracker::BitValue &V = RC[I];
if (V.Type == BitTracker::BitValue::Ref && V.RefI.Reg == RD.Reg)
return false;
IsConst = IsConst && (V.is(0) || V.is(1));
}
if (IsConst)
return false;
if (TopV.is(0) || TopV.is(1)) {
bool S = TopV.is(1);
for (--W; W > 0 && RC[W-1].is(S); --W)
;
Len = W;
Signed = S;
// The sign bit must be a part of the field being extended.
if (Signed)
++Len;
} else {
// This could still be a sign-extended extract.
assert(TopV.Type == BitTracker::BitValue::Ref);
if (TopV.RefI.Reg == RD.Reg || TopV.RefI.Pos == W-1)
return false;
for (--W; W > 0 && RC[W-1] == TopV; --W)
;
// The top bits of RC are copies of TopV. One occurrence of TopV will
// be a part of the field.
Len = W + 1;
Signed = true;
}
// This would be just a copy. It should be handled elsewhere.
if (Len == RW)
return false;
LLVM_DEBUG({
dbgs() << __func__ << " on reg: " << printReg(RD.Reg, &HRI, RD.Sub)
<< ", MI: " << *MI;
dbgs() << "Cell: " << RC << '\n';
dbgs() << "Expected bitfield size: " << Len << " bits, "
<< (Signed ? "sign" : "zero") << "-extended\n";
});
bool Changed = false;
for (unsigned R = AVs.find_first(); R != 0; R = AVs.find_next(R)) {
if (!BT.has(R))
continue;
const BitTracker::RegisterCell &SC = BT.lookup(R);
unsigned SW = SC.width();
// The source can be longer than the destination, as long as its size is
// a multiple of the size of the destination. Also, we would need to be
// able to refer to the subregister in the source that would be of the
// same size as the destination, but only check the sizes here.
if (SW < RW || (SW % RW) != 0)
continue;
// The field can start at any offset in SC as long as it contains Len
// bits and does not cross subregister boundary (if the source register
// is longer than the destination).
unsigned Off = 0;
while (Off <= SW-Len) {
unsigned OE = (Off+Len)/RW;
if (OE != Off/RW) {
// The assumption here is that if the source (R) is longer than the
// destination, then the destination is a sequence of words of
// size RW, and each such word in R can be accessed via a subregister.
//
// If the beginning and the end of the field cross the subregister
// boundary, advance to the next subregister.
Off = OE*RW;
continue;
}
if (HBS::isEqual(RC, 0, SC, Off, Len))
break;
++Off;
}
if (Off > SW-Len)
continue;
// Found match.
unsigned ExtOpc = 0;
if (Off == 0) {
if (Len == 8)
ExtOpc = Signed ? Hexagon::A2_sxtb : Hexagon::A2_zxtb;
else if (Len == 16)
ExtOpc = Signed ? Hexagon::A2_sxth : Hexagon::A2_zxth;
else if (Len < 10 && !Signed)
ExtOpc = Hexagon::A2_andir;
}
if (ExtOpc == 0) {
ExtOpc =
Signed ? (RW == 32 ? Hexagon::S4_extract : Hexagon::S4_extractp)
: (RW == 32 ? Hexagon::S2_extractu : Hexagon::S2_extractup);
}
unsigned SR = 0;
// This only recognizes isub_lo and isub_hi.
if (RW != SW && RW*2 != SW)
continue;
if (RW != SW)
SR = (Off/RW == 0) ? Hexagon::isub_lo : Hexagon::isub_hi;
Off = Off % RW;
if (!validateReg({R,SR}, ExtOpc, 1))
continue;
// Don't generate the same instruction as the one being optimized.
if (MI->getOpcode() == ExtOpc) {
// All possible ExtOpc's have the source in operand(1).
const MachineOperand &SrcOp = MI->getOperand(1);
if (SrcOp.getReg() == R)
continue;
}
DebugLoc DL = MI->getDebugLoc();
MachineBasicBlock &B = *MI->getParent();
unsigned NewR = MRI.createVirtualRegister(FRC);
auto At = MI->isPHI() ? B.getFirstNonPHI()
: MachineBasicBlock::iterator(MI);
auto MIB = BuildMI(B, At, DL, HII.get(ExtOpc), NewR)
.addReg(R, 0, SR);
switch (ExtOpc) {
case Hexagon::A2_sxtb:
case Hexagon::A2_zxtb:
case Hexagon::A2_sxth:
case Hexagon::A2_zxth:
break;
case Hexagon::A2_andir:
MIB.addImm((1u << Len) - 1);
break;
case Hexagon::S4_extract:
case Hexagon::S2_extractu:
case Hexagon::S4_extractp:
case Hexagon::S2_extractup:
MIB.addImm(Len)
.addImm(Off);
break;
default:
llvm_unreachable("Unexpected opcode");
}
HBS::replaceReg(RD.Reg, NewR, MRI);
BT.put(BitTracker::RegisterRef(NewR), RC);
Changed = true;
break;
}
return Changed;
}
bool BitSimplification::simplifyRCmp0(MachineInstr *MI,
BitTracker::RegisterRef RD) {
unsigned Opc = MI->getOpcode();
if (Opc != Hexagon::A4_rcmpeqi && Opc != Hexagon::A4_rcmpneqi)
return false;
MachineOperand &CmpOp = MI->getOperand(2);
if (!CmpOp.isImm() || CmpOp.getImm() != 0)
return false;
const TargetRegisterClass *FRC = HBS::getFinalVRegClass(RD, MRI);
if (FRC != &Hexagon::IntRegsRegClass && FRC != &Hexagon::DoubleRegsRegClass)
return false;
assert(RD.Sub == 0);
MachineBasicBlock &B = *MI->getParent();
const DebugLoc &DL = MI->getDebugLoc();
auto At = MI->isPHI() ? B.getFirstNonPHI()
: MachineBasicBlock::iterator(MI);
bool KnownZ = true;
bool KnownNZ = false;
BitTracker::RegisterRef SR = MI->getOperand(1);
if (!BT.has(SR.Reg))
return false;
const BitTracker::RegisterCell &SC = BT.lookup(SR.Reg);
unsigned F, W;
if (!HBS::getSubregMask(SR, F, W, MRI))
return false;
for (uint16_t I = F; I != F+W; ++I) {
const BitTracker::BitValue &V = SC[I];
if (!V.is(0))
KnownZ = false;
if (V.is(1))
KnownNZ = true;
}
auto ReplaceWithConst = [&] (int C) {
unsigned NewR = MRI.createVirtualRegister(FRC);
BuildMI(B, At, DL, HII.get(Hexagon::A2_tfrsi), NewR)
.addImm(C);
HBS::replaceReg(RD.Reg, NewR, MRI);
BitTracker::RegisterCell NewRC(W);
for (uint16_t I = 0; I != W; ++I) {
NewRC[I] = BitTracker::BitValue(C & 1);
C = unsigned(C) >> 1;
}
BT.put(BitTracker::RegisterRef(NewR), NewRC);
return true;
};
auto IsNonZero = [] (const MachineOperand &Op) {
if (Op.isGlobal() || Op.isBlockAddress())
return true;
if (Op.isImm())
return Op.getImm() != 0;
if (Op.isCImm())
return !Op.getCImm()->isZero();
if (Op.isFPImm())
return !Op.getFPImm()->isZero();
return false;
};
auto IsZero = [] (const MachineOperand &Op) {
if (Op.isGlobal() || Op.isBlockAddress())
return false;
if (Op.isImm())
return Op.getImm() == 0;
if (Op.isCImm())
return Op.getCImm()->isZero();
if (Op.isFPImm())
return Op.getFPImm()->isZero();
return false;
};
// If the source register is known to be 0 or non-0, the comparison can
// be folded to a load of a constant.
if (KnownZ || KnownNZ) {
assert(KnownZ != KnownNZ && "Register cannot be both 0 and non-0");
return ReplaceWithConst(KnownZ == (Opc == Hexagon::A4_rcmpeqi));
}
// Special case: if the compare comes from a C2_muxii, then we know the
// two possible constants that can be the source value.
MachineInstr *InpDef = MRI.getVRegDef(SR.Reg);
if (!InpDef)
return false;
if (SR.Sub == 0 && InpDef->getOpcode() == Hexagon::C2_muxii) {
MachineOperand &Src1 = InpDef->getOperand(2);
MachineOperand &Src2 = InpDef->getOperand(3);
// Check if both are non-zero.
bool KnownNZ1 = IsNonZero(Src1), KnownNZ2 = IsNonZero(Src2);
if (KnownNZ1 && KnownNZ2)
return ReplaceWithConst(Opc == Hexagon::A4_rcmpneqi);
// Check if both are zero.
bool KnownZ1 = IsZero(Src1), KnownZ2 = IsZero(Src2);
if (KnownZ1 && KnownZ2)
return ReplaceWithConst(Opc == Hexagon::A4_rcmpeqi);
// If for both operands we know that they are either 0 or non-0,
// replace the comparison with a C2_muxii, using the same predicate
// register, but with operands substituted with 0/1 accordingly.
if ((KnownZ1 || KnownNZ1) && (KnownZ2 || KnownNZ2)) {
unsigned NewR = MRI.createVirtualRegister(FRC);
BuildMI(B, At, DL, HII.get(Hexagon::C2_muxii), NewR)
.addReg(InpDef->getOperand(1).getReg())
.addImm(KnownZ1 == (Opc == Hexagon::A4_rcmpeqi))
.addImm(KnownZ2 == (Opc == Hexagon::A4_rcmpeqi));
HBS::replaceReg(RD.Reg, NewR, MRI);
// Create a new cell with only the least significant bit unknown.
BitTracker::RegisterCell NewRC(W);
NewRC[0] = BitTracker::BitValue::self();
NewRC.fill(1, W, BitTracker::BitValue::Zero);
BT.put(BitTracker::RegisterRef(NewR), NewRC);
return true;
}
}
return false;
}
bool BitSimplification::processBlock(MachineBasicBlock &B,
const RegisterSet &AVs) {
if (!BT.reached(&B))
return false;
bool Changed = false;
RegisterSet AVB = AVs;
RegisterSet Defs;
for (auto I = B.begin(), E = B.end(); I != E; ++I, AVB.insert(Defs)) {
MachineInstr *MI = &*I;
Defs.clear();
HBS::getInstrDefs(*MI, Defs);
unsigned Opc = MI->getOpcode();
if (Opc == TargetOpcode::COPY || Opc == TargetOpcode::REG_SEQUENCE)
continue;
if (MI->mayStore()) {
bool T = genStoreUpperHalf(MI);
T = T || genStoreImmediate(MI);
Changed |= T;
continue;
}
if (Defs.count() != 1)
continue;
const MachineOperand &Op0 = MI->getOperand(0);
if (!Op0.isReg() || !Op0.isDef())
continue;
BitTracker::RegisterRef RD = Op0;
if (!BT.has(RD.Reg))
continue;
const TargetRegisterClass *FRC = HBS::getFinalVRegClass(RD, MRI);
const BitTracker::RegisterCell &RC = BT.lookup(RD.Reg);
if (FRC->getID() == Hexagon::DoubleRegsRegClassID) {
bool T = genPackhl(MI, RD, RC);
T = T || simplifyExtractLow(MI, RD, RC, AVB);
Changed |= T;
continue;
}
if (FRC->getID() == Hexagon::IntRegsRegClassID) {
bool T = genBitSplit(MI, RD, RC, AVB);
T = T || simplifyExtractLow(MI, RD, RC, AVB);
T = T || genExtractHalf(MI, RD, RC);
T = T || genCombineHalf(MI, RD, RC);
T = T || genExtractLow(MI, RD, RC);
T = T || simplifyRCmp0(MI, RD);
Changed |= T;
continue;
}
if (FRC->getID() == Hexagon::PredRegsRegClassID) {
bool T = simplifyTstbit(MI, RD, RC);
Changed |= T;
continue;
}
}
return Changed;
}
bool HexagonBitSimplify::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HRI = *HST.getRegisterInfo();
auto &HII = *HST.getInstrInfo();
MDT = &getAnalysis<MachineDominatorTree>();
MachineRegisterInfo &MRI = MF.getRegInfo();
bool Changed;
Changed = DeadCodeElimination(MF, *MDT).run();
const HexagonEvaluator HE(HRI, MRI, HII, MF);
BitTracker BT(HE, MF);
LLVM_DEBUG(BT.trace(true));
BT.run();
MachineBasicBlock &Entry = MF.front();
RegisterSet AIG; // Available registers for IG.
ConstGeneration ImmG(BT, HII, MRI);
Changed |= visitBlock(Entry, ImmG, AIG);
RegisterSet ARE; // Available registers for RIE.
RedundantInstrElimination RIE(BT, HII, HRI, MRI);
bool Ried = visitBlock(Entry, RIE, ARE);
if (Ried) {
Changed = true;
BT.run();
}
RegisterSet ACG; // Available registers for CG.
CopyGeneration CopyG(BT, HII, HRI, MRI);
Changed |= visitBlock(Entry, CopyG, ACG);
RegisterSet ACP; // Available registers for CP.
CopyPropagation CopyP(HRI, MRI);
Changed |= visitBlock(Entry, CopyP, ACP);
Changed = DeadCodeElimination(MF, *MDT).run() || Changed;
BT.run();
RegisterSet ABS; // Available registers for BS.
BitSimplification BitS(BT, *MDT, HII, HRI, MRI, MF);
Changed |= visitBlock(Entry, BitS, ABS);
Changed = DeadCodeElimination(MF, *MDT).run() || Changed;
if (Changed) {
for (auto &B : MF)
for (auto &I : B)
I.clearKillInfo();
DeadCodeElimination(MF, *MDT).run();
}
return Changed;
}
// Recognize loops where the code at the end of the loop matches the code
// before the entry of the loop, and the matching code is such that is can
// be simplified. This pass relies on the bit simplification above and only
// prepares code in a way that can be handled by the bit simplifcation.
//
// This is the motivating testcase (and explanation):
//
// {
// loop0(.LBB0_2, r1) // %for.body.preheader
// r5:4 = memd(r0++#8)
// }
// {
// r3 = lsr(r4, #16)
// r7:6 = combine(r5, r5)
// }
// {
// r3 = insert(r5, #16, #16)
// r7:6 = vlsrw(r7:6, #16)
// }
// .LBB0_2:
// {
// memh(r2+#4) = r5
// memh(r2+#6) = r6 # R6 is really R5.H
// }
// {
// r2 = add(r2, #8)
// memh(r2+#0) = r4
// memh(r2+#2) = r3 # R3 is really R4.H
// }
// {
// r5:4 = memd(r0++#8)
// }
// { # "Shuffling" code that sets up R3 and R6
// r3 = lsr(r4, #16) # so that their halves can be stored in the
// r7:6 = combine(r5, r5) # next iteration. This could be folded into
// } # the stores if the code was at the beginning
// { # of the loop iteration. Since the same code
// r3 = insert(r5, #16, #16) # precedes the loop, it can actually be moved
// r7:6 = vlsrw(r7:6, #16) # there.
// }:endloop0
//
//
// The outcome:
//
// {
// loop0(.LBB0_2, r1)
// r5:4 = memd(r0++#8)
// }
// .LBB0_2:
// {
// memh(r2+#4) = r5
// memh(r2+#6) = r5.h
// }
// {
// r2 = add(r2, #8)
// memh(r2+#0) = r4
// memh(r2+#2) = r4.h
// }
// {
// r5:4 = memd(r0++#8)
// }:endloop0
namespace llvm {
FunctionPass *createHexagonLoopRescheduling();
void initializeHexagonLoopReschedulingPass(PassRegistry&);
} // end namespace llvm
namespace {
class HexagonLoopRescheduling : public MachineFunctionPass {
public:
static char ID;
HexagonLoopRescheduling() : MachineFunctionPass(ID) {
initializeHexagonLoopReschedulingPass(*PassRegistry::getPassRegistry());
}
bool runOnMachineFunction(MachineFunction &MF) override;
private:
const HexagonInstrInfo *HII = nullptr;
const HexagonRegisterInfo *HRI = nullptr;
MachineRegisterInfo *MRI = nullptr;
BitTracker *BTP = nullptr;
struct LoopCand {
LoopCand(MachineBasicBlock *lb, MachineBasicBlock *pb,
MachineBasicBlock *eb) : LB(lb), PB(pb), EB(eb) {}
MachineBasicBlock *LB, *PB, *EB;
};
using InstrList = std::vector<MachineInstr *>;
struct InstrGroup {
BitTracker::RegisterRef Inp, Out;
InstrList Ins;
};
struct PhiInfo {
PhiInfo(MachineInstr &P, MachineBasicBlock &B);
unsigned DefR;
BitTracker::RegisterRef LR, PR; // Loop Register, Preheader Register
MachineBasicBlock *LB, *PB; // Loop Block, Preheader Block
};
static unsigned getDefReg(const MachineInstr *MI);
bool isConst(unsigned Reg) const;
bool isBitShuffle(const MachineInstr *MI, unsigned DefR) const;
bool isStoreInput(const MachineInstr *MI, unsigned DefR) const;
bool isShuffleOf(unsigned OutR, unsigned InpR) const;
bool isSameShuffle(unsigned OutR1, unsigned InpR1, unsigned OutR2,
unsigned &InpR2) const;
void moveGroup(InstrGroup &G, MachineBasicBlock &LB, MachineBasicBlock &PB,
MachineBasicBlock::iterator At, unsigned OldPhiR, unsigned NewPredR);
bool processLoop(LoopCand &C);
};
} // end anonymous namespace
char HexagonLoopRescheduling::ID = 0;
INITIALIZE_PASS(HexagonLoopRescheduling, "hexagon-loop-resched",
"Hexagon Loop Rescheduling", false, false)
HexagonLoopRescheduling::PhiInfo::PhiInfo(MachineInstr &P,
MachineBasicBlock &B) {
DefR = HexagonLoopRescheduling::getDefReg(&P);
LB = &B;
PB = nullptr;
for (unsigned i = 1, n = P.getNumOperands(); i < n; i += 2) {
const MachineOperand &OpB = P.getOperand(i+1);
if (OpB.getMBB() == &B) {
LR = P.getOperand(i);
continue;
}
PB = OpB.getMBB();
PR = P.getOperand(i);
}
}
unsigned HexagonLoopRescheduling::getDefReg(const MachineInstr *MI) {
RegisterSet Defs;
HBS::getInstrDefs(*MI, Defs);
if (Defs.count() != 1)
return 0;
return Defs.find_first();
}
bool HexagonLoopRescheduling::isConst(unsigned Reg) const {
if (!BTP->has(Reg))
return false;
const BitTracker::RegisterCell &RC = BTP->lookup(Reg);
for (unsigned i = 0, w = RC.width(); i < w; ++i) {
const BitTracker::BitValue &V = RC[i];
if (!V.is(0) && !V.is(1))
return false;
}
return true;
}
bool HexagonLoopRescheduling::isBitShuffle(const MachineInstr *MI,
unsigned DefR) const {
unsigned Opc = MI->getOpcode();
switch (Opc) {
case TargetOpcode::COPY:
case Hexagon::S2_lsr_i_r:
case Hexagon::S2_asr_i_r:
case Hexagon::S2_asl_i_r:
case Hexagon::S2_lsr_i_p:
case Hexagon::S2_asr_i_p:
case Hexagon::S2_asl_i_p:
case Hexagon::S2_insert:
case Hexagon::A2_or:
case Hexagon::A2_orp:
case Hexagon::A2_and:
case Hexagon::A2_andp:
case Hexagon::A2_combinew:
case Hexagon::A4_combineri:
case Hexagon::A4_combineir:
case Hexagon::A2_combineii:
case Hexagon::A4_combineii:
case Hexagon::A2_combine_ll:
case Hexagon::A2_combine_lh:
case Hexagon::A2_combine_hl:
case Hexagon::A2_combine_hh:
return true;
}
return false;
}
bool HexagonLoopRescheduling::isStoreInput(const MachineInstr *MI,
unsigned InpR) const {
for (unsigned i = 0, n = MI->getNumOperands(); i < n; ++i) {
const MachineOperand &Op = MI->getOperand(i);
if (!Op.isReg())
continue;
if (Op.getReg() == InpR)
return i == n-1;
}
return false;
}
bool HexagonLoopRescheduling::isShuffleOf(unsigned OutR, unsigned InpR) const {
if (!BTP->has(OutR) || !BTP->has(InpR))
return false;
const BitTracker::RegisterCell &OutC = BTP->lookup(OutR);
for (unsigned i = 0, w = OutC.width(); i < w; ++i) {
const BitTracker::BitValue &V = OutC[i];
if (V.Type != BitTracker::BitValue::Ref)
continue;
if (V.RefI.Reg != InpR)
return false;
}
return true;
}
bool HexagonLoopRescheduling::isSameShuffle(unsigned OutR1, unsigned InpR1,
unsigned OutR2, unsigned &InpR2) const {
if (!BTP->has(OutR1) || !BTP->has(InpR1) || !BTP->has(OutR2))
return false;
const BitTracker::RegisterCell &OutC1 = BTP->lookup(OutR1);
const BitTracker::RegisterCell &OutC2 = BTP->lookup(OutR2);
unsigned W = OutC1.width();
unsigned MatchR = 0;
if (W != OutC2.width())
return false;
for (unsigned i = 0; i < W; ++i) {
const BitTracker::BitValue &V1 = OutC1[i], &V2 = OutC2[i];
if (V1.Type != V2.Type || V1.Type == BitTracker::BitValue::One)
return false;
if (V1.Type != BitTracker::BitValue::Ref)
continue;
if (V1.RefI.Pos != V2.RefI.Pos)
return false;
if (V1.RefI.Reg != InpR1)
return false;
if (V2.RefI.Reg == 0 || V2.RefI.Reg == OutR2)
return false;
if (!MatchR)
MatchR = V2.RefI.Reg;
else if (V2.RefI.Reg != MatchR)
return false;
}
InpR2 = MatchR;
return true;
}
void HexagonLoopRescheduling::moveGroup(InstrGroup &G, MachineBasicBlock &LB,
MachineBasicBlock &PB, MachineBasicBlock::iterator At, unsigned OldPhiR,
unsigned NewPredR) {
DenseMap<unsigned,unsigned> RegMap;
const TargetRegisterClass *PhiRC = MRI->getRegClass(NewPredR);
unsigned PhiR = MRI->createVirtualRegister(PhiRC);
BuildMI(LB, At, At->getDebugLoc(), HII->get(TargetOpcode::PHI), PhiR)
.addReg(NewPredR)
.addMBB(&PB)
.addReg(G.Inp.Reg)
.addMBB(&LB);
RegMap.insert(std::make_pair(G.Inp.Reg, PhiR));
for (unsigned i = G.Ins.size(); i > 0; --i) {
const MachineInstr *SI = G.Ins[i-1];
unsigned DR = getDefReg(SI);
const TargetRegisterClass *RC = MRI->getRegClass(DR);
unsigned NewDR = MRI->createVirtualRegister(RC);
DebugLoc DL = SI->getDebugLoc();
auto MIB = BuildMI(LB, At, DL, HII->get(SI->getOpcode()), NewDR);
for (unsigned j = 0, m = SI->getNumOperands(); j < m; ++j) {
const MachineOperand &Op = SI->getOperand(j);
if (!Op.isReg()) {
MIB.add(Op);
continue;
}
if (!Op.isUse())
continue;
unsigned UseR = RegMap[Op.getReg()];
MIB.addReg(UseR, 0, Op.getSubReg());
}
RegMap.insert(std::make_pair(DR, NewDR));
}
HBS::replaceReg(OldPhiR, RegMap[G.Out.Reg], *MRI);
}
bool HexagonLoopRescheduling::processLoop(LoopCand &C) {
LLVM_DEBUG(dbgs() << "Processing loop in " << printMBBReference(*C.LB)
<< "\n");
std::vector<PhiInfo> Phis;
for (auto &I : *C.LB) {
if (!I.isPHI())
break;
unsigned PR = getDefReg(&I);
if (isConst(PR))
continue;
bool BadUse = false, GoodUse = false;
for (auto UI = MRI->use_begin(PR), UE = MRI->use_end(); UI != UE; ++UI) {
MachineInstr *UseI = UI->getParent();
if (UseI->getParent() != C.LB) {
BadUse = true;
break;
}
if (isBitShuffle(UseI, PR) || isStoreInput(UseI, PR))
GoodUse = true;
}
if (BadUse || !GoodUse)
continue;
Phis.push_back(PhiInfo(I, *C.LB));
}
LLVM_DEBUG({
dbgs() << "Phis: {";
for (auto &I : Phis) {
dbgs() << ' ' << printReg(I.DefR, HRI) << "=phi("
<< printReg(I.PR.Reg, HRI, I.PR.Sub) << ":b" << I.PB->getNumber()
<< ',' << printReg(I.LR.Reg, HRI, I.LR.Sub) << ":b"
<< I.LB->getNumber() << ')';
}
dbgs() << " }\n";
});
if (Phis.empty())
return false;
bool Changed = false;
InstrList ShufIns;
// Go backwards in the block: for each bit shuffling instruction, check
// if that instruction could potentially be moved to the front of the loop:
// the output of the loop cannot be used in a non-shuffling instruction
// in this loop.
for (auto I = C.LB->rbegin(), E = C.LB->rend(); I != E; ++I) {
if (I->isTerminator())
continue;
if (I->isPHI())
break;
RegisterSet Defs;
HBS::getInstrDefs(*I, Defs);
if (Defs.count() != 1)
continue;
unsigned DefR = Defs.find_first();
if (!TargetRegisterInfo::isVirtualRegister(DefR))
continue;
if (!isBitShuffle(&*I, DefR))
continue;
bool BadUse = false;
for (auto UI = MRI->use_begin(DefR), UE = MRI->use_end(); UI != UE; ++UI) {
MachineInstr *UseI = UI->getParent();
if (UseI->getParent() == C.LB) {
if (UseI->isPHI()) {
// If the use is in a phi node in this loop, then it should be
// the value corresponding to the back edge.
unsigned Idx = UI.getOperandNo();
if (UseI->getOperand(Idx+1).getMBB() != C.LB)
BadUse = true;
} else {
auto F = find(ShufIns, UseI);
if (F == ShufIns.end())
BadUse = true;
}
} else {
// There is a use outside of the loop, but there is no epilog block
// suitable for a copy-out.
if (C.EB == nullptr)
BadUse = true;
}
if (BadUse)
break;
}
if (BadUse)
continue;
ShufIns.push_back(&*I);
}
// Partition the list of shuffling instructions into instruction groups,
// where each group has to be moved as a whole (i.e. a group is a chain of
// dependent instructions). A group produces a single live output register,
// which is meant to be the input of the loop phi node (although this is
// not checked here yet). It also uses a single register as its input,
// which is some value produced in the loop body. After moving the group
// to the beginning of the loop, that input register would need to be
// the loop-carried register (through a phi node) instead of the (currently
// loop-carried) output register.
using InstrGroupList = std::vector<InstrGroup>;
InstrGroupList Groups;
for (unsigned i = 0, n = ShufIns.size(); i < n; ++i) {
MachineInstr *SI = ShufIns[i];
if (SI == nullptr)
continue;
InstrGroup G;
G.Ins.push_back(SI);
G.Out.Reg = getDefReg(SI);
RegisterSet Inputs;
HBS::getInstrUses(*SI, Inputs);
for (unsigned j = i+1; j < n; ++j) {
MachineInstr *MI = ShufIns[j];
if (MI == nullptr)
continue;
RegisterSet Defs;
HBS::getInstrDefs(*MI, Defs);
// If this instruction does not define any pending inputs, skip it.
if (!Defs.intersects(Inputs))
continue;
// Otherwise, add it to the current group and remove the inputs that
// are defined by MI.
G.Ins.push_back(MI);
Inputs.remove(Defs);
// Then add all registers used by MI.
HBS::getInstrUses(*MI, Inputs);
ShufIns[j] = nullptr;
}
// Only add a group if it requires at most one register.
if (Inputs.count() > 1)
continue;
auto LoopInpEq = [G] (const PhiInfo &P) -> bool {
return G.Out.Reg == P.LR.Reg;
};
if (llvm::find_if(Phis, LoopInpEq) == Phis.end())
continue;
G.Inp.Reg = Inputs.find_first();
Groups.push_back(G);
}
LLVM_DEBUG({
for (unsigned i = 0, n = Groups.size(); i < n; ++i) {
InstrGroup &G = Groups[i];
dbgs() << "Group[" << i << "] inp: "
<< printReg(G.Inp.Reg, HRI, G.Inp.Sub)
<< " out: " << printReg(G.Out.Reg, HRI, G.Out.Sub) << "\n";
for (unsigned j = 0, m = G.Ins.size(); j < m; ++j)
dbgs() << " " << *G.Ins[j];
}
});
for (unsigned i = 0, n = Groups.size(); i < n; ++i) {
InstrGroup &G = Groups[i];
if (!isShuffleOf(G.Out.Reg, G.Inp.Reg))
continue;
auto LoopInpEq = [G] (const PhiInfo &P) -> bool {
return G.Out.Reg == P.LR.Reg;
};
auto F = llvm::find_if(Phis, LoopInpEq);
if (F == Phis.end())
continue;
unsigned PrehR = 0;
if (!isSameShuffle(G.Out.Reg, G.Inp.Reg, F->PR.Reg, PrehR)) {
const MachineInstr *DefPrehR = MRI->getVRegDef(F->PR.Reg);
unsigned Opc = DefPrehR->getOpcode();
if (Opc != Hexagon::A2_tfrsi && Opc != Hexagon::A2_tfrpi)
continue;
if (!DefPrehR->getOperand(1).isImm())
continue;
if (DefPrehR->getOperand(1).getImm() != 0)
continue;
const TargetRegisterClass *RC = MRI->getRegClass(G.Inp.Reg);
if (RC != MRI->getRegClass(F->PR.Reg)) {
PrehR = MRI->createVirtualRegister(RC);
unsigned TfrI = (RC == &Hexagon::IntRegsRegClass) ? Hexagon::A2_tfrsi
: Hexagon::A2_tfrpi;
auto T = C.PB->getFirstTerminator();
DebugLoc DL = (T != C.PB->end()) ? T->getDebugLoc() : DebugLoc();
BuildMI(*C.PB, T, DL, HII->get(TfrI), PrehR)
.addImm(0);
} else {
PrehR = F->PR.Reg;
}
}
// isSameShuffle could match with PrehR being of a wider class than
// G.Inp.Reg, for example if G shuffles the low 32 bits of its input,
// it would match for the input being a 32-bit register, and PrehR
// being a 64-bit register (where the low 32 bits match). This could
// be handled, but for now skip these cases.
if (MRI->getRegClass(PrehR) != MRI->getRegClass(G.Inp.Reg))
continue;
moveGroup(G, *F->LB, *F->PB, F->LB->getFirstNonPHI(), F->DefR, PrehR);
Changed = true;
}
return Changed;
}
bool HexagonLoopRescheduling::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
auto &HST = MF.getSubtarget<HexagonSubtarget>();
HII = HST.getInstrInfo();
HRI = HST.getRegisterInfo();
MRI = &MF.getRegInfo();
const HexagonEvaluator HE(*HRI, *MRI, *HII, MF);
BitTracker BT(HE, MF);
LLVM_DEBUG(BT.trace(true));
BT.run();
BTP = &BT;
std::vector<LoopCand> Cand;
for (auto &B : MF) {
if (B.pred_size() != 2 || B.succ_size() != 2)
continue;
MachineBasicBlock *PB = nullptr;
bool IsLoop = false;
for (auto PI = B.pred_begin(), PE = B.pred_end(); PI != PE; ++PI) {
if (*PI != &B)
PB = *PI;
else
IsLoop = true;
}
if (!IsLoop)
continue;
MachineBasicBlock *EB = nullptr;
for (auto SI = B.succ_begin(), SE = B.succ_end(); SI != SE; ++SI) {
if (*SI == &B)
continue;
// Set EP to the epilog block, if it has only 1 predecessor (i.e. the
// edge from B to EP is non-critical.
if ((*SI)->pred_size() == 1)
EB = *SI;
break;
}
Cand.push_back(LoopCand(&B, PB, EB));
}
bool Changed = false;
for (auto &C : Cand)
Changed |= processLoop(C);
return Changed;
}
//===----------------------------------------------------------------------===//
// Public Constructor Functions
//===----------------------------------------------------------------------===//
FunctionPass *llvm::createHexagonLoopRescheduling() {
return new HexagonLoopRescheduling();
}
FunctionPass *llvm::createHexagonBitSimplify() {
return new HexagonBitSimplify();
}
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