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llvm-mirror/lib/Target/Mips/MipsLongBranch.cpp
Simon Dardis fc4a194816 [mips] Add partial support for R6 in the long branch pass 
MIPSR6 introduced several new jump instructions and deprecated
the use of the 'j' instruction. For microMIPS32R6, 'j' was removed
entirely and it only has non delay slot jumps.

This patch adds support for MIPSR6 by using some R6 instructions--
'bc' instead of 'j', 'jic $reg, 0' instead of 'jalr $zero, $reg'--
and modifies the sequences not to use delay slots for R6.

Reviewers: atanasyan

Reviewed By: atanasyan

Subscribers: dschuff, arichardson, llvm-commits

Differential Revision: https://reviews.llvm.org/D40786

llvm-svn: 320703
2017-12-14 14:55:25 +00:00

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//===- MipsLongBranch.cpp - Emit long branches ----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass expands a branch or jump instruction into a long branch if its
// offset is too large to fit into its immediate field.
//
// FIXME: Fix pc-region jump instructions which cross 256MB segment boundaries.
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/MipsABIInfo.h"
#include "MCTargetDesc/MipsBaseInfo.h"
#include "MCTargetDesc/MipsMCNaCl.h"
#include "MCTargetDesc/MipsMCTargetDesc.h"
#include "Mips.h"
#include "MipsInstrInfo.h"
#include "MipsMachineFunction.h"
#include "MipsSubtarget.h"
#include "MipsTargetMachine.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/MachineBasicBlock.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/TargetSubtargetInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetMachine.h"
#include <cassert>
#include <cstdint>
#include <iterator>
using namespace llvm;
#define DEBUG_TYPE "mips-long-branch"
STATISTIC(LongBranches, "Number of long branches.");
static cl::opt<bool> SkipLongBranch(
"skip-mips-long-branch",
cl::init(false),
cl::desc("MIPS: Skip long branch pass."),
cl::Hidden);
static cl::opt<bool> ForceLongBranch(
"force-mips-long-branch",
cl::init(false),
cl::desc("MIPS: Expand all branches to long format."),
cl::Hidden);
namespace {
using Iter = MachineBasicBlock::iterator;
using ReverseIter = MachineBasicBlock::reverse_iterator;
struct MBBInfo {
uint64_t Size = 0;
uint64_t Address;
bool HasLongBranch = false;
MachineInstr *Br = nullptr;
MBBInfo() = default;
};
class MipsLongBranch : public MachineFunctionPass {
public:
static char ID;
MipsLongBranch()
: MachineFunctionPass(ID), ABI(MipsABIInfo::Unknown()) {}
StringRef getPassName() const override { return "Mips Long Branch"; }
bool runOnMachineFunction(MachineFunction &F) override;
MachineFunctionProperties getRequiredProperties() const override {
return MachineFunctionProperties().set(
MachineFunctionProperties::Property::NoVRegs);
}
private:
void splitMBB(MachineBasicBlock *MBB);
void initMBBInfo();
int64_t computeOffset(const MachineInstr *Br);
void replaceBranch(MachineBasicBlock &MBB, Iter Br, const DebugLoc &DL,
MachineBasicBlock *MBBOpnd);
void expandToLongBranch(MBBInfo &Info);
MachineFunction *MF;
SmallVector<MBBInfo, 16> MBBInfos;
bool IsPIC;
MipsABIInfo ABI;
unsigned LongBranchSeqSize;
};
} // end anonymous namespace
char MipsLongBranch::ID = 0;
/// Iterate over list of Br's operands and search for a MachineBasicBlock
/// operand.
static MachineBasicBlock *getTargetMBB(const MachineInstr &Br) {
for (unsigned I = 0, E = Br.getDesc().getNumOperands(); I < E; ++I) {
const MachineOperand &MO = Br.getOperand(I);
if (MO.isMBB())
return MO.getMBB();
}
llvm_unreachable("This instruction does not have an MBB operand.");
}
// Traverse the list of instructions backwards until a non-debug instruction is
// found or it reaches E.
static ReverseIter getNonDebugInstr(ReverseIter B, const ReverseIter &E) {
for (; B != E; ++B)
if (!B->isDebugValue())
return B;
return E;
}
// Split MBB if it has two direct jumps/branches.
void MipsLongBranch::splitMBB(MachineBasicBlock *MBB) {
ReverseIter End = MBB->rend();
ReverseIter LastBr = getNonDebugInstr(MBB->rbegin(), End);
// Return if MBB has no branch instructions.
if ((LastBr == End) ||
(!LastBr->isConditionalBranch() && !LastBr->isUnconditionalBranch()))
return;
ReverseIter FirstBr = getNonDebugInstr(std::next(LastBr), End);
// MBB has only one branch instruction if FirstBr is not a branch
// instruction.
if ((FirstBr == End) ||
(!FirstBr->isConditionalBranch() && !FirstBr->isUnconditionalBranch()))
return;
assert(!FirstBr->isIndirectBranch() && "Unexpected indirect branch found.");
// Create a new MBB. Move instructions in MBB to the newly created MBB.
MachineBasicBlock *NewMBB =
MF->CreateMachineBasicBlock(MBB->getBasicBlock());
// Insert NewMBB and fix control flow.
MachineBasicBlock *Tgt = getTargetMBB(*FirstBr);
NewMBB->transferSuccessors(MBB);
NewMBB->removeSuccessor(Tgt, true);
MBB->addSuccessor(NewMBB);
MBB->addSuccessor(Tgt);
MF->insert(std::next(MachineFunction::iterator(MBB)), NewMBB);
NewMBB->splice(NewMBB->end(), MBB, LastBr.getReverse(), MBB->end());
}
// Fill MBBInfos.
void MipsLongBranch::initMBBInfo() {
// Split the MBBs if they have two branches. Each basic block should have at
// most one branch after this loop is executed.
for (auto &MBB : *MF)
splitMBB(&MBB);
MF->RenumberBlocks();
MBBInfos.clear();
MBBInfos.resize(MF->size());
const MipsInstrInfo *TII =
static_cast<const MipsInstrInfo *>(MF->getSubtarget().getInstrInfo());
for (unsigned I = 0, E = MBBInfos.size(); I < E; ++I) {
MachineBasicBlock *MBB = MF->getBlockNumbered(I);
// Compute size of MBB.
for (MachineBasicBlock::instr_iterator MI = MBB->instr_begin();
MI != MBB->instr_end(); ++MI)
MBBInfos[I].Size += TII->getInstSizeInBytes(*MI);
// Search for MBB's branch instruction.
ReverseIter End = MBB->rend();
ReverseIter Br = getNonDebugInstr(MBB->rbegin(), End);
if ((Br != End) && !Br->isIndirectBranch() &&
(Br->isConditionalBranch() || (Br->isUnconditionalBranch() && IsPIC)))
MBBInfos[I].Br = &*Br;
}
}
// Compute offset of branch in number of bytes.
int64_t MipsLongBranch::computeOffset(const MachineInstr *Br) {
int64_t Offset = 0;
int ThisMBB = Br->getParent()->getNumber();
int TargetMBB = getTargetMBB(*Br)->getNumber();
// Compute offset of a forward branch.
if (ThisMBB < TargetMBB) {
for (int N = ThisMBB + 1; N < TargetMBB; ++N)
Offset += MBBInfos[N].Size;
return Offset + 4;
}
// Compute offset of a backward branch.
for (int N = ThisMBB; N >= TargetMBB; --N)
Offset += MBBInfos[N].Size;
return -Offset + 4;
}
// Replace Br with a branch which has the opposite condition code and a
// MachineBasicBlock operand MBBOpnd.
void MipsLongBranch::replaceBranch(MachineBasicBlock &MBB, Iter Br,
const DebugLoc &DL,
MachineBasicBlock *MBBOpnd) {
const MipsInstrInfo *TII = static_cast<const MipsInstrInfo *>(
MBB.getParent()->getSubtarget().getInstrInfo());
unsigned NewOpc = TII->getOppositeBranchOpc(Br->getOpcode());
const MCInstrDesc &NewDesc = TII->get(NewOpc);
MachineInstrBuilder MIB = BuildMI(MBB, Br, DL, NewDesc);
for (unsigned I = 0, E = Br->getDesc().getNumOperands(); I < E; ++I) {
MachineOperand &MO = Br->getOperand(I);
if (!MO.isReg()) {
assert(MO.isMBB() && "MBB operand expected.");
break;
}
MIB.addReg(MO.getReg());
}
MIB.addMBB(MBBOpnd);
if (Br->hasDelaySlot()) {
// Bundle the instruction in the delay slot to the newly created branch
// and erase the original branch.
assert(Br->isBundledWithSucc());
MachineBasicBlock::instr_iterator II = Br.getInstrIterator();
MIBundleBuilder(&*MIB).append((++II)->removeFromBundle());
}
Br->eraseFromParent();
}
// Expand branch instructions to long branches.
// TODO: This function has to be fixed for beqz16 and bnez16, because it
// currently assumes that all branches have 16-bit offsets, and will produce
// wrong code if branches whose allowed offsets are [-128, -126, ..., 126]
// are present.
void MipsLongBranch::expandToLongBranch(MBBInfo &I) {
MachineBasicBlock::iterator Pos;
MachineBasicBlock *MBB = I.Br->getParent(), *TgtMBB = getTargetMBB(*I.Br);
DebugLoc DL = I.Br->getDebugLoc();
const BasicBlock *BB = MBB->getBasicBlock();
MachineFunction::iterator FallThroughMBB = ++MachineFunction::iterator(MBB);
MachineBasicBlock *LongBrMBB = MF->CreateMachineBasicBlock(BB);
const MipsSubtarget &Subtarget =
static_cast<const MipsSubtarget &>(MF->getSubtarget());
const MipsInstrInfo *TII =
static_cast<const MipsInstrInfo *>(Subtarget.getInstrInfo());
MF->insert(FallThroughMBB, LongBrMBB);
MBB->replaceSuccessor(TgtMBB, LongBrMBB);
if (IsPIC) {
MachineBasicBlock *BalTgtMBB = MF->CreateMachineBasicBlock(BB);
MF->insert(FallThroughMBB, BalTgtMBB);
LongBrMBB->addSuccessor(BalTgtMBB);
BalTgtMBB->addSuccessor(TgtMBB);
// We must select between the MIPS32r6/MIPS64r6 BALC (which is a normal
// instruction) and the pre-MIPS32r6/MIPS64r6 definition (which is an
// pseudo-instruction wrapping BGEZAL).
const unsigned BalOp =
Subtarget.hasMips32r6()
? Subtarget.inMicroMipsMode() ? Mips::BALC_MMR6 : Mips::BALC
: Mips::BAL_BR;
if (!ABI.IsN64()) {
// Pre R6:
// $longbr:
// addiu $sp, $sp, -8
// sw $ra, 0($sp)
// lui $at, %hi($tgt - $baltgt)
// bal $baltgt
// addiu $at, $at, %lo($tgt - $baltgt)
// $baltgt:
// addu $at, $ra, $at
// lw $ra, 0($sp)
// jr $at
// addiu $sp, $sp, 8
// $fallthrough:
//
// R6:
// $longbr:
// addiu $sp, $sp, -8
// sw $ra, 0($sp)
// lui $at, %hi($tgt - $baltgt)
// addiu $at, $at, %lo($tgt - $baltgt)
// balc $baltgt
// $baltgt:
// addu $at, $ra, $at
// lw $ra, 0($sp)
// addiu $sp, $sp, 8
// jic $at, 0
// $fallthrough:
Pos = LongBrMBB->begin();
BuildMI(*LongBrMBB, Pos, DL, TII->get(Mips::ADDiu), Mips::SP)
.addReg(Mips::SP).addImm(-8);
BuildMI(*LongBrMBB, Pos, DL, TII->get(Mips::SW)).addReg(Mips::RA)
.addReg(Mips::SP).addImm(0);
// LUi and ADDiu instructions create 32-bit offset of the target basic
// block from the target of BAL(C) instruction. We cannot use immediate
// value for this offset because it cannot be determined accurately when
// the program has inline assembly statements. We therefore use the
// relocation expressions %hi($tgt-$baltgt) and %lo($tgt-$baltgt) which
// are resolved during the fixup, so the values will always be correct.
//
// Since we cannot create %hi($tgt-$baltgt) and %lo($tgt-$baltgt)
// expressions at this point (it is possible only at the MC layer),
// we replace LUi and ADDiu with pseudo instructions
// LONG_BRANCH_LUi and LONG_BRANCH_ADDiu, and add both basic
// blocks as operands to these instructions. When lowering these pseudo
// instructions to LUi and ADDiu in the MC layer, we will create
// %hi($tgt-$baltgt) and %lo($tgt-$baltgt) expressions and add them as
// operands to lowered instructions.
BuildMI(*LongBrMBB, Pos, DL, TII->get(Mips::LONG_BRANCH_LUi), Mips::AT)
.addMBB(TgtMBB).addMBB(BalTgtMBB);
MachineInstrBuilder BalInstr =
BuildMI(*MF, DL, TII->get(BalOp)).addMBB(BalTgtMBB);
MachineInstrBuilder ADDiuInstr =
BuildMI(*MF, DL, TII->get(Mips::LONG_BRANCH_ADDiu), Mips::AT)
.addReg(Mips::AT)
.addMBB(TgtMBB)
.addMBB(BalTgtMBB);
if (Subtarget.hasMips32r6()) {
LongBrMBB->insert(Pos, ADDiuInstr);
LongBrMBB->insert(Pos, BalInstr);
} else {
LongBrMBB->insert(Pos, BalInstr);
LongBrMBB->insert(Pos, ADDiuInstr);
LongBrMBB->rbegin()->bundleWithPred();
}
Pos = BalTgtMBB->begin();
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::ADDu), Mips::AT)
.addReg(Mips::RA).addReg(Mips::AT);
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::LW), Mips::RA)
.addReg(Mips::SP).addImm(0);
if (Subtarget.isTargetNaCl())
// Bundle-align the target of indirect branch JR.
TgtMBB->setAlignment(MIPS_NACL_BUNDLE_ALIGN);
// In NaCl, modifying the sp is not allowed in branch delay slot.
// For MIPS32R6, we can skip using a delay slot branch.
if (Subtarget.isTargetNaCl() || Subtarget.hasMips32r6())
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::ADDiu), Mips::SP)
.addReg(Mips::SP).addImm(8);
if (Subtarget.hasMips32r6()) {
const unsigned JICOp =
Subtarget.inMicroMipsMode() ? Mips::JIC_MMR6 : Mips::JIC;
BuildMI(*BalTgtMBB, Pos, DL, TII->get(JICOp))
.addReg(Mips::AT)
.addImm(0);
} else {
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::JR)).addReg(Mips::AT);
if (Subtarget.isTargetNaCl()) {
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::NOP));
} else
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::ADDiu), Mips::SP)
.addReg(Mips::SP)
.addImm(8);
BalTgtMBB->rbegin()->bundleWithPred();
}
} else {
// Pre R6:
// $longbr:
// daddiu $sp, $sp, -16
// sd $ra, 0($sp)
// daddiu $at, $zero, %hi($tgt - $baltgt)
// dsll $at, $at, 16
// bal $baltgt
// daddiu $at, $at, %lo($tgt - $baltgt)
// $baltgt:
// daddu $at, $ra, $at
// ld $ra, 0($sp)
// jr64 $at
// daddiu $sp, $sp, 16
// $fallthrough:
// R6:
// $longbr:
// daddiu $sp, $sp, -16
// sd $ra, 0($sp)
// daddiu $at, $zero, %hi($tgt - $baltgt)
// dsll $at, $at, 16
// daddiu $at, $at, %lo($tgt - $baltgt)
// balc $baltgt
// $baltgt:
// daddu $at, $ra, $at
// ld $ra, 0($sp)
// daddiu $sp, $sp, 16
// jic $at, 0
// $fallthrough:
// We assume the branch is within-function, and that offset is within
// +/- 2GB. High 32 bits will therefore always be zero.
// Note that this will work even if the offset is negative, because
// of the +1 modification that's added in that case. For example, if the
// offset is -1MB (0xFFFFFFFFFFF00000), the computation for %higher is
//
// 0xFFFFFFFFFFF00000 + 0x80008000 = 0x000000007FF08000
//
// and the bits [47:32] are zero. For %highest
//
// 0xFFFFFFFFFFF00000 + 0x800080008000 = 0x000080007FF08000
//
// and the bits [63:48] are zero.
Pos = LongBrMBB->begin();
BuildMI(*LongBrMBB, Pos, DL, TII->get(Mips::DADDiu), Mips::SP_64)
.addReg(Mips::SP_64).addImm(-16);
BuildMI(*LongBrMBB, Pos, DL, TII->get(Mips::SD)).addReg(Mips::RA_64)
.addReg(Mips::SP_64).addImm(0);
BuildMI(*LongBrMBB, Pos, DL, TII->get(Mips::LONG_BRANCH_DADDiu),
Mips::AT_64).addReg(Mips::ZERO_64)
.addMBB(TgtMBB, MipsII::MO_ABS_HI).addMBB(BalTgtMBB);
BuildMI(*LongBrMBB, Pos, DL, TII->get(Mips::DSLL), Mips::AT_64)
.addReg(Mips::AT_64).addImm(16);
MachineInstrBuilder BalInstr =
BuildMI(*MF, DL, TII->get(BalOp)).addMBB(BalTgtMBB);
MachineInstrBuilder DADDiuInstr =
BuildMI(*MF, DL, TII->get(Mips::LONG_BRANCH_DADDiu), Mips::AT_64)
.addReg(Mips::AT_64)
.addMBB(TgtMBB, MipsII::MO_ABS_LO)
.addMBB(BalTgtMBB);
if (Subtarget.hasMips32r6()) {
LongBrMBB->insert(Pos, DADDiuInstr);
LongBrMBB->insert(Pos, BalInstr);
} else {
LongBrMBB->insert(Pos, BalInstr);
LongBrMBB->insert(Pos, DADDiuInstr);
LongBrMBB->rbegin()->bundleWithPred();
}
Pos = BalTgtMBB->begin();
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::DADDu), Mips::AT_64)
.addReg(Mips::RA_64).addReg(Mips::AT_64);
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::LD), Mips::RA_64)
.addReg(Mips::SP_64).addImm(0);
if (Subtarget.hasMips64r6()) {
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::DADDiu), Mips::SP_64)
.addReg(Mips::SP_64)
.addImm(16);
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::JIC64))
.addReg(Mips::AT_64)
.addImm(0);
} else {
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::JR64)).addReg(Mips::AT_64);
BuildMI(*BalTgtMBB, Pos, DL, TII->get(Mips::DADDiu), Mips::SP_64)
.addReg(Mips::SP_64)
.addImm(16);
BalTgtMBB->rbegin()->bundleWithPred();
}
}
assert(LongBrMBB->size() + BalTgtMBB->size() == LongBranchSeqSize);
} else {
// Pre R6: R6:
// $longbr: $longbr:
// j $tgt bc $tgt
// nop $fallthrough
// $fallthrough:
//
Pos = LongBrMBB->begin();
LongBrMBB->addSuccessor(TgtMBB);
if (Subtarget.hasMips32r6())
BuildMI(*LongBrMBB, Pos, DL,
TII->get(Subtarget.inMicroMipsMode() ? Mips::BC_MMR6 : Mips::BC))
.addMBB(TgtMBB);
else
MIBundleBuilder(*LongBrMBB, Pos)
.append(BuildMI(*MF, DL, TII->get(Mips::J)).addMBB(TgtMBB))
.append(BuildMI(*MF, DL, TII->get(Mips::NOP)));
assert(LongBrMBB->size() == LongBranchSeqSize);
}
if (I.Br->isUnconditionalBranch()) {
// Change branch destination.
assert(I.Br->getDesc().getNumOperands() == 1);
I.Br->RemoveOperand(0);
I.Br->addOperand(MachineOperand::CreateMBB(LongBrMBB));
} else
// Change branch destination and reverse condition.
replaceBranch(*MBB, I.Br, DL, &*FallThroughMBB);
}
static void emitGPDisp(MachineFunction &F, const MipsInstrInfo *TII) {
MachineBasicBlock &MBB = F.front();
MachineBasicBlock::iterator I = MBB.begin();
DebugLoc DL = MBB.findDebugLoc(MBB.begin());
BuildMI(MBB, I, DL, TII->get(Mips::LUi), Mips::V0)
.addExternalSymbol("_gp_disp", MipsII::MO_ABS_HI);
BuildMI(MBB, I, DL, TII->get(Mips::ADDiu), Mips::V0)
.addReg(Mips::V0).addExternalSymbol("_gp_disp", MipsII::MO_ABS_LO);
MBB.removeLiveIn(Mips::V0);
}
bool MipsLongBranch::runOnMachineFunction(MachineFunction &F) {
const MipsSubtarget &STI =
static_cast<const MipsSubtarget &>(F.getSubtarget());
const MipsInstrInfo *TII =
static_cast<const MipsInstrInfo *>(STI.getInstrInfo());
const TargetMachine& TM = F.getTarget();
IsPIC = TM.isPositionIndependent();
ABI = static_cast<const MipsTargetMachine &>(TM).getABI();
LongBranchSeqSize = IsPIC ? ((ABI.IsN64() || STI.isTargetNaCl()) ? 10 : 9)
: (STI.hasMips32r6() ? 1 : 2);
if (STI.inMips16Mode() || !STI.enableLongBranchPass())
return false;
if (IsPIC && static_cast<const MipsTargetMachine &>(TM).getABI().IsO32() &&
F.getInfo<MipsFunctionInfo>()->globalBaseRegSet())
emitGPDisp(F, TII);
if (SkipLongBranch)
return true;
MF = &F;
initMBBInfo();
SmallVectorImpl<MBBInfo>::iterator I, E = MBBInfos.end();
bool EverMadeChange = false, MadeChange = true;
while (MadeChange) {
MadeChange = false;
for (I = MBBInfos.begin(); I != E; ++I) {
// Skip if this MBB doesn't have a branch or the branch has already been
// converted to a long branch.
if (!I->Br || I->HasLongBranch)
continue;
int ShVal = STI.inMicroMipsMode() ? 2 : 4;
int64_t Offset = computeOffset(I->Br) / ShVal;
if (STI.isTargetNaCl()) {
// The offset calculation does not include sandboxing instructions
// that will be added later in the MC layer. Since at this point we
// don't know the exact amount of code that "sandboxing" will add, we
// conservatively estimate that code will not grow more than 100%.
Offset *= 2;
}
// Check if offset fits into 16-bit immediate field of branches.
if (!ForceLongBranch && isInt<16>(Offset))
continue;
I->HasLongBranch = true;
I->Size += LongBranchSeqSize * 4;
++LongBranches;
EverMadeChange = MadeChange = true;
}
}
if (!EverMadeChange)
return true;
// Compute basic block addresses.
if (IsPIC) {
uint64_t Address = 0;
for (I = MBBInfos.begin(); I != E; Address += I->Size, ++I)
I->Address = Address;
}
// Do the expansion.
for (I = MBBInfos.begin(); I != E; ++I)
if (I->HasLongBranch)
expandToLongBranch(*I);
MF->RenumberBlocks();
return true;
}
/// createMipsLongBranchPass - Returns a pass that converts branches to long
/// branches.
FunctionPass *llvm::createMipsLongBranchPass() { return new MipsLongBranch(); }
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