MachineInstrBuilder
MipsInstrInfo::genInstrWithNewOpc(unsigned NewOpc,
MachineBasicBlock::iterator I) const {
MachineInstrBuilder MIB;
// Certain branches have two forms: e.g beq $1, $zero, dest vs beqz $1, dest
// Pick the zero form of the branch for readable assembly and for greater
// branch distance in non-microMIPS mode.
// Additional MIPSR6 does not permit the use of register $zero for compact
// branches.
// FIXME: Certain atomic sequences on mips64 generate 32bit references to
// Mips::ZERO, which is incorrect. This test should be updated to use
// Subtarget.getABI().GetZeroReg() when those atomic sequences and others
// are fixed.
int ZeroOperandPosition = -1;
bool BranchWithZeroOperand = false;
if (I->isBranch() && !I->isPseudo()) {
auto TRI = I->getParent()->getParent()->getSubtarget().getRegisterInfo();
ZeroOperandPosition = I->findRegisterUseOperandIdx(Mips::ZERO, false, TRI);
BranchWithZeroOperand = ZeroOperandPosition != -1;
}
if (BranchWithZeroOperand) {
switch (NewOpc) {
case Mips::BEQC:
NewOpc = Mips::BEQZC;
break;
case Mips::BNEC:
NewOpc = Mips::BNEZC;
break;
case Mips::BGEC:
NewOpc = Mips::BGEZC;
break;
case Mips::BLTC:
NewOpc = Mips::BLTZC;
break;
case Mips::BEQC64:
NewOpc = Mips::BEQZC64;
break;
case Mips::BNEC64:
NewOpc = Mips::BNEZC64;
break;
}
}
MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), get(NewOpc));
// For MIPSR6 JI*C requires an immediate 0 as an operand, JIALC(64) an
// immediate 0 as an operand and requires the removal of it's %RA<imp-def>
// implicit operand as copying the implicit operations of the instructio we're
// looking at will give us the correct flags.
if (NewOpc == Mips::JIC || NewOpc == Mips::JIALC || NewOpc == Mips::JIC64 ||
NewOpc == Mips::JIALC64) {
if (NewOpc == Mips::JIALC || NewOpc == Mips::JIALC64)
MIB->RemoveOperand(0);
for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
MIB.add(I->getOperand(J));
}
MIB.addImm(0);
} else {
for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
if (BranchWithZeroOperand && (unsigned)ZeroOperandPosition == J)
continue;
MIB.add(I->getOperand(J));
}
}
MIB.copyImplicitOps(*I);
MIB.setMemRefs(I->memoperands_begin(), I->memoperands_end());
return MIB;
}
MachineInstrBuilder
MipsInstrInfo::genInstrWithNewOpc(unsigned NewOpc,
MachineBasicBlock::iterator I) const {
MachineInstrBuilder MIB;
// Certain branches have two forms: e.g beq $1, $zero, dst vs beqz $1, dest
// Pick the zero form of the branch for readable assembly and for greater
// branch distance in non-microMIPS mode.
// FIXME: Certain atomic sequences on mips64 generate 32bit references to
// Mips::ZERO, which is incorrect. This test should be updated to use
// Subtarget.getABI().GetZeroReg() when those atomic sequences and others
// are fixed.
bool BranchWithZeroOperand =
(I->isBranch() && !I->isPseudo() && I->getOperand(1).isReg() &&
(I->getOperand(1).getReg() == Mips::ZERO ||
I->getOperand(1).getReg() == Mips::ZERO_64));
if (BranchWithZeroOperand) {
switch (NewOpc) {
case Mips::BEQC:
NewOpc = Mips::BEQZC;
break;
case Mips::BNEC:
NewOpc = Mips::BNEZC;
break;
case Mips::BGEC:
NewOpc = Mips::BGEZC;
break;
case Mips::BLTC:
NewOpc = Mips::BLTZC;
break;
}
}
MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), get(NewOpc));
// For MIPSR6 JI*C requires an immediate 0 as an operand, JIALC(64) an
// immediate 0 as an operand and requires the removal of it's %RA<imp-def>
// implicit operand as copying the implicit operations of the instructio we're
// looking at will give us the correct flags.
if (NewOpc == Mips::JIC || NewOpc == Mips::JIALC || NewOpc == Mips::JIC64 ||
NewOpc == Mips::JIALC64) {
if (NewOpc == Mips::JIALC || NewOpc == Mips::JIALC64)
MIB->RemoveOperand(0);
for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
MIB.addOperand(I->getOperand(J));
}
MIB.addImm(0);
} else if (BranchWithZeroOperand) {
// For MIPSR6 and microMIPS branches with an explicit zero operand, copy
// everything after the zero.
MIB.addOperand(I->getOperand(0));
for (unsigned J = 2, E = I->getDesc().getNumOperands(); J < E; ++J) {
MIB.addOperand(I->getOperand(J));
}
} else {
// All other cases copy all other operands.
for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
MIB.addOperand(I->getOperand(J));
}
}
MIB.copyImplicitOps(*I);
MIB.setMemRefs(I->memoperands_begin(), I->memoperands_end());
return MIB;
}
bool PatmosInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify) const {
// If the client does not want to only simplify the branch,
// the output arguments must be initialized.
assert(AllowModify || (TBB==0 && FBB==0 && Cond.size()==0));
// Start from the bottom of the block and work up, examining the
// terminator instructions.
MachineBasicBlock::iterator I = MBB.end();
while (I != MBB.begin()) {
--I;
if (I->isDebugValue() || I->isPseudo())
continue;
// Working from the bottom, when we see a non-terminator inst, we're done.
if (!isUnpredicatedTerminator(I))
break;
// A terminator that isn't a (direct) branch can't easily be handled
// by this analysis.
if (!I->isBranch() || I->isIndirectBranch())
return true;
// Handle Unconditional branches
if (!isPredicated(I)) {
// fix instruction, if necessary
if (!I->isUnconditionalBranch()) fixOpcodeForGuard(I);
// TBB is used to indicate the unconditional destination.
TBB = getBranchTarget(I);
if (AllowModify) {
// If the block has any instructions after an uncond branch, delete them.
while (llvm::next(I) != MBB.end())
llvm::next(I)->eraseFromParent();
}
continue;
}
// Handle conditional branches
if (isPredicated(I)) {
// fix instruction, if necessary
if (!I->isConditionalBranch()) fixOpcodeForGuard(I);
// we only treat the first conditional branch in a row
if (Cond.size() > 0)
return true;
// Get branch condition
int i = I->findFirstPredOperandIdx();
assert(i != -1 );
Cond.push_back(I->getOperand(i)); // reg
Cond.push_back(I->getOperand(i+1)); // flag
// We've processed an unconditional branch before,
// the unconditional target goes to FBB now
if (TBB) FBB = TBB;
// target of conditional branch goes to TBB
TBB = getBranchTarget(I);
continue;
}
// we explicitly leave or continue.
llvm_unreachable("AnalyzeBranch error.");
}
// left the loop? then we're done
return false;
}