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llvm-mirror/lib/Target/Hexagon/HexagonGenPredicate.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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//===- HexagonGenPredicate.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 "HexagonInstrInfo.h"
#include "HexagonSubtarget.h"
#include "llvm/ADT/SetVector.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/Pass.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <utility>
#define DEBUG_TYPE "gen-pred"
using namespace llvm;
namespace llvm {
void initializeHexagonGenPredicatePass(PassRegistry& Registry);
FunctionPass *createHexagonGenPredicate();
} // end namespace llvm
namespace {
struct Register {
unsigned R, S;
Register(unsigned r = 0, unsigned s = 0) : R(r), S(s) {}
Register(const MachineOperand &MO) : R(MO.getReg()), S(MO.getSubReg()) {}
bool operator== (const Register &Reg) const {
return R == Reg.R && S == Reg.S;
}
bool operator< (const Register &Reg) const {
return R < Reg.R || (R == Reg.R && S < Reg.S);
}
};
struct PrintRegister {
friend raw_ostream &operator<< (raw_ostream &OS, const PrintRegister &PR);
PrintRegister(Register R, const TargetRegisterInfo &I) : Reg(R), TRI(I) {}
private:
Register Reg;
const TargetRegisterInfo &TRI;
};
raw_ostream &operator<< (raw_ostream &OS, const PrintRegister &PR)
LLVM_ATTRIBUTE_UNUSED;
raw_ostream &operator<< (raw_ostream &OS, const PrintRegister &PR) {
return OS << printReg(PR.Reg.R, &PR.TRI, PR.Reg.S);
}
class HexagonGenPredicate : public MachineFunctionPass {
public:
static char ID;
HexagonGenPredicate() : MachineFunctionPass(ID) {
initializeHexagonGenPredicatePass(*PassRegistry::getPassRegistry());
}
StringRef getPassName() const override {
return "Hexagon generate predicate operations";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<MachineDominatorTree>();
AU.addPreserved<MachineDominatorTree>();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool runOnMachineFunction(MachineFunction &MF) override;
private:
using VectOfInst = SetVector<MachineInstr *>;
using SetOfReg = std::set<Register>;
using RegToRegMap = std::map<Register, Register>;
const HexagonInstrInfo *TII = nullptr;
const HexagonRegisterInfo *TRI = nullptr;
MachineRegisterInfo *MRI = nullptr;
SetOfReg PredGPRs;
VectOfInst PUsers;
RegToRegMap G2P;
bool isPredReg(unsigned R);
void collectPredicateGPR(MachineFunction &MF);
void processPredicateGPR(const Register &Reg);
unsigned getPredForm(unsigned Opc);
bool isConvertibleToPredForm(const MachineInstr *MI);
bool isScalarCmp(unsigned Opc);
bool isScalarPred(Register PredReg);
Register getPredRegFor(const Register &Reg);
bool convertToPredForm(MachineInstr *MI);
bool eliminatePredCopies(MachineFunction &MF);
};
} // end anonymous namespace
char HexagonGenPredicate::ID = 0;
INITIALIZE_PASS_BEGIN(HexagonGenPredicate, "hexagon-gen-pred",
"Hexagon generate predicate operations", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_END(HexagonGenPredicate, "hexagon-gen-pred",
"Hexagon generate predicate operations", false, false)
bool HexagonGenPredicate::isPredReg(unsigned R) {
if (!TargetRegisterInfo::isVirtualRegister(R))
return false;
const TargetRegisterClass *RC = MRI->getRegClass(R);
return RC == &Hexagon::PredRegsRegClass;
}
unsigned HexagonGenPredicate::getPredForm(unsigned Opc) {
using namespace Hexagon;
switch (Opc) {
case A2_and:
case A2_andp:
return C2_and;
case A4_andn:
case A4_andnp:
return C2_andn;
case M4_and_and:
return C4_and_and;
case M4_and_andn:
return C4_and_andn;
case M4_and_or:
return C4_and_or;
case A2_or:
case A2_orp:
return C2_or;
case A4_orn:
case A4_ornp:
return C2_orn;
case M4_or_and:
return C4_or_and;
case M4_or_andn:
return C4_or_andn;
case M4_or_or:
return C4_or_or;
case A2_xor:
case A2_xorp:
return C2_xor;
case C2_tfrrp:
return COPY;
}
// The opcode corresponding to 0 is TargetOpcode::PHI. We can use 0 here
// to denote "none", but we need to make sure that none of the valid opcodes
// that we return will ever be 0.
static_assert(PHI == 0, "Use different value for <none>");
return 0;
}
bool HexagonGenPredicate::isConvertibleToPredForm(const MachineInstr *MI) {
unsigned Opc = MI->getOpcode();
if (getPredForm(Opc) != 0)
return true;
// Comparisons against 0 are also convertible. This does not apply to
// A4_rcmpeqi or A4_rcmpneqi, since they produce values 0 or 1, which
// may not match the value that the predicate register would have if
// it was converted to a predicate form.
switch (Opc) {
case Hexagon::C2_cmpeqi:
case Hexagon::C4_cmpneqi:
if (MI->getOperand(2).isImm() && MI->getOperand(2).getImm() == 0)
return true;
break;
}
return false;
}
void HexagonGenPredicate::collectPredicateGPR(MachineFunction &MF) {
for (MachineFunction::iterator A = MF.begin(), Z = MF.end(); A != Z; ++A) {
MachineBasicBlock &B = *A;
for (MachineBasicBlock::iterator I = B.begin(), E = B.end(); I != E; ++I) {
MachineInstr *MI = &*I;
unsigned Opc = MI->getOpcode();
switch (Opc) {
case Hexagon::C2_tfrpr:
case TargetOpcode::COPY:
if (isPredReg(MI->getOperand(1).getReg())) {
Register RD = MI->getOperand(0);
if (TargetRegisterInfo::isVirtualRegister(RD.R))
PredGPRs.insert(RD);
}
break;
}
}
}
}
void HexagonGenPredicate::processPredicateGPR(const Register &Reg) {
LLVM_DEBUG(dbgs() << __func__ << ": " << printReg(Reg.R, TRI, Reg.S) << "\n");
using use_iterator = MachineRegisterInfo::use_iterator;
use_iterator I = MRI->use_begin(Reg.R), E = MRI->use_end();
if (I == E) {
LLVM_DEBUG(dbgs() << "Dead reg: " << printReg(Reg.R, TRI, Reg.S) << '\n');
MachineInstr *DefI = MRI->getVRegDef(Reg.R);
DefI->eraseFromParent();
return;
}
for (; I != E; ++I) {
MachineInstr *UseI = I->getParent();
if (isConvertibleToPredForm(UseI))
PUsers.insert(UseI);
}
}
Register HexagonGenPredicate::getPredRegFor(const Register &Reg) {
// Create a predicate register for a given Reg. The newly created register
// will have its value copied from Reg, so that it can be later used as
// an operand in other instructions.
assert(TargetRegisterInfo::isVirtualRegister(Reg.R));
RegToRegMap::iterator F = G2P.find(Reg);
if (F != G2P.end())
return F->second;
LLVM_DEBUG(dbgs() << __func__ << ": " << PrintRegister(Reg, *TRI));
MachineInstr *DefI = MRI->getVRegDef(Reg.R);
assert(DefI);
unsigned Opc = DefI->getOpcode();
if (Opc == Hexagon::C2_tfrpr || Opc == TargetOpcode::COPY) {
assert(DefI->getOperand(0).isDef() && DefI->getOperand(1).isUse());
Register PR = DefI->getOperand(1);
G2P.insert(std::make_pair(Reg, PR));
LLVM_DEBUG(dbgs() << " -> " << PrintRegister(PR, *TRI) << '\n');
return PR;
}
MachineBasicBlock &B = *DefI->getParent();
DebugLoc DL = DefI->getDebugLoc();
const TargetRegisterClass *PredRC = &Hexagon::PredRegsRegClass;
unsigned NewPR = MRI->createVirtualRegister(PredRC);
// For convertible instructions, do not modify them, so that they can
// be converted later. Generate a copy from Reg to NewPR.
if (isConvertibleToPredForm(DefI)) {
MachineBasicBlock::iterator DefIt = DefI;
BuildMI(B, std::next(DefIt), DL, TII->get(TargetOpcode::COPY), NewPR)
.addReg(Reg.R, 0, Reg.S);
G2P.insert(std::make_pair(Reg, Register(NewPR)));
LLVM_DEBUG(dbgs() << " -> !" << PrintRegister(Register(NewPR), *TRI)
<< '\n');
return Register(NewPR);
}
llvm_unreachable("Invalid argument");
}
bool HexagonGenPredicate::isScalarCmp(unsigned Opc) {
switch (Opc) {
case Hexagon::C2_cmpeq:
case Hexagon::C2_cmpgt:
case Hexagon::C2_cmpgtu:
case Hexagon::C2_cmpeqp:
case Hexagon::C2_cmpgtp:
case Hexagon::C2_cmpgtup:
case Hexagon::C2_cmpeqi:
case Hexagon::C2_cmpgti:
case Hexagon::C2_cmpgtui:
case Hexagon::C2_cmpgei:
case Hexagon::C2_cmpgeui:
case Hexagon::C4_cmpneqi:
case Hexagon::C4_cmpltei:
case Hexagon::C4_cmplteui:
case Hexagon::C4_cmpneq:
case Hexagon::C4_cmplte:
case Hexagon::C4_cmplteu:
case Hexagon::A4_cmpbeq:
case Hexagon::A4_cmpbeqi:
case Hexagon::A4_cmpbgtu:
case Hexagon::A4_cmpbgtui:
case Hexagon::A4_cmpbgt:
case Hexagon::A4_cmpbgti:
case Hexagon::A4_cmpheq:
case Hexagon::A4_cmphgt:
case Hexagon::A4_cmphgtu:
case Hexagon::A4_cmpheqi:
case Hexagon::A4_cmphgti:
case Hexagon::A4_cmphgtui:
return true;
}
return false;
}
bool HexagonGenPredicate::isScalarPred(Register PredReg) {
std::queue<Register> WorkQ;
WorkQ.push(PredReg);
while (!WorkQ.empty()) {
Register PR = WorkQ.front();
WorkQ.pop();
const MachineInstr *DefI = MRI->getVRegDef(PR.R);
if (!DefI)
return false;
unsigned DefOpc = DefI->getOpcode();
switch (DefOpc) {
case TargetOpcode::COPY: {
const TargetRegisterClass *PredRC = &Hexagon::PredRegsRegClass;
if (MRI->getRegClass(PR.R) != PredRC)
return false;
// If it is a copy between two predicate registers, fall through.
LLVM_FALLTHROUGH;
}
case Hexagon::C2_and:
case Hexagon::C2_andn:
case Hexagon::C4_and_and:
case Hexagon::C4_and_andn:
case Hexagon::C4_and_or:
case Hexagon::C2_or:
case Hexagon::C2_orn:
case Hexagon::C4_or_and:
case Hexagon::C4_or_andn:
case Hexagon::C4_or_or:
case Hexagon::C4_or_orn:
case Hexagon::C2_xor:
// Add operands to the queue.
for (const MachineOperand &MO : DefI->operands())
if (MO.isReg() && MO.isUse())
WorkQ.push(Register(MO.getReg()));
break;
// All non-vector compares are ok, everything else is bad.
default:
return isScalarCmp(DefOpc);
}
}
return true;
}
bool HexagonGenPredicate::convertToPredForm(MachineInstr *MI) {
LLVM_DEBUG(dbgs() << __func__ << ": " << MI << " " << *MI);
unsigned Opc = MI->getOpcode();
assert(isConvertibleToPredForm(MI));
unsigned NumOps = MI->getNumOperands();
for (unsigned i = 0; i < NumOps; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isUse())
continue;
Register Reg(MO);
if (Reg.S && Reg.S != Hexagon::isub_lo)
return false;
if (!PredGPRs.count(Reg))
return false;
}
MachineBasicBlock &B = *MI->getParent();
DebugLoc DL = MI->getDebugLoc();
unsigned NewOpc = getPredForm(Opc);
// Special case for comparisons against 0.
if (NewOpc == 0) {
switch (Opc) {
case Hexagon::C2_cmpeqi:
NewOpc = Hexagon::C2_not;
break;
case Hexagon::C4_cmpneqi:
NewOpc = TargetOpcode::COPY;
break;
default:
return false;
}
// If it's a scalar predicate register, then all bits in it are
// the same. Otherwise, to determine whether all bits are 0 or not
// we would need to use any8.
Register PR = getPredRegFor(MI->getOperand(1));
if (!isScalarPred(PR))
return false;
// This will skip the immediate argument when creating the predicate
// version instruction.
NumOps = 2;
}
// Some sanity: check that def is in operand #0.
MachineOperand &Op0 = MI->getOperand(0);
assert(Op0.isDef());
Register OutR(Op0);
// Don't use getPredRegFor, since it will create an association between
// the argument and a created predicate register (i.e. it will insert a
// copy if a new predicate register is created).
const TargetRegisterClass *PredRC = &Hexagon::PredRegsRegClass;
Register NewPR = MRI->createVirtualRegister(PredRC);
MachineInstrBuilder MIB = BuildMI(B, MI, DL, TII->get(NewOpc), NewPR.R);
// Add predicate counterparts of the GPRs.
for (unsigned i = 1; i < NumOps; ++i) {
Register GPR = MI->getOperand(i);
Register Pred = getPredRegFor(GPR);
MIB.addReg(Pred.R, 0, Pred.S);
}
LLVM_DEBUG(dbgs() << "generated: " << *MIB);
// Generate a copy-out: NewGPR = NewPR, and replace all uses of OutR
// with NewGPR.
const TargetRegisterClass *RC = MRI->getRegClass(OutR.R);
unsigned NewOutR = MRI->createVirtualRegister(RC);
BuildMI(B, MI, DL, TII->get(TargetOpcode::COPY), NewOutR)
.addReg(NewPR.R, 0, NewPR.S);
MRI->replaceRegWith(OutR.R, NewOutR);
MI->eraseFromParent();
// If the processed instruction was C2_tfrrp (i.e. Rn = Pm; Pk = Rn),
// then the output will be a predicate register. Do not visit the
// users of it.
if (!isPredReg(NewOutR)) {
Register R(NewOutR);
PredGPRs.insert(R);
processPredicateGPR(R);
}
return true;
}
bool HexagonGenPredicate::eliminatePredCopies(MachineFunction &MF) {
LLVM_DEBUG(dbgs() << __func__ << "\n");
const TargetRegisterClass *PredRC = &Hexagon::PredRegsRegClass;
bool Changed = false;
VectOfInst Erase;
// First, replace copies
// IntR = PredR1
// PredR2 = IntR
// with
// PredR2 = PredR1
// Such sequences can be generated when a copy-into-pred is generated from
// a gpr register holding a result of a convertible instruction. After
// the convertible instruction is converted, its predicate result will be
// copied back into the original gpr.
for (MachineBasicBlock &MBB : MF) {
for (MachineInstr &MI : MBB) {
if (MI.getOpcode() != TargetOpcode::COPY)
continue;
Register DR = MI.getOperand(0);
Register SR = MI.getOperand(1);
if (!TargetRegisterInfo::isVirtualRegister(DR.R))
continue;
if (!TargetRegisterInfo::isVirtualRegister(SR.R))
continue;
if (MRI->getRegClass(DR.R) != PredRC)
continue;
if (MRI->getRegClass(SR.R) != PredRC)
continue;
assert(!DR.S && !SR.S && "Unexpected subregister");
MRI->replaceRegWith(DR.R, SR.R);
Erase.insert(&MI);
Changed = true;
}
}
for (VectOfInst::iterator I = Erase.begin(), E = Erase.end(); I != E; ++I)
(*I)->eraseFromParent();
return Changed;
}
bool HexagonGenPredicate::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
TII = MF.getSubtarget<HexagonSubtarget>().getInstrInfo();
TRI = MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MRI = &MF.getRegInfo();
PredGPRs.clear();
PUsers.clear();
G2P.clear();
bool Changed = false;
collectPredicateGPR(MF);
for (SetOfReg::iterator I = PredGPRs.begin(), E = PredGPRs.end(); I != E; ++I)
processPredicateGPR(*I);
bool Again;
do {
Again = false;
VectOfInst Processed, Copy;
using iterator = VectOfInst::iterator;
Copy = PUsers;
for (iterator I = Copy.begin(), E = Copy.end(); I != E; ++I) {
MachineInstr *MI = *I;
bool Done = convertToPredForm(MI);
if (Done) {
Processed.insert(MI);
Again = true;
}
}
Changed |= Again;
auto Done = [Processed] (MachineInstr *MI) -> bool {
return Processed.count(MI);
};
PUsers.remove_if(Done);
} while (Again);
Changed |= eliminatePredCopies(MF);
return Changed;
}
FunctionPass *llvm::createHexagonGenPredicate() {
return new HexagonGenPredicate();
}
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