BranchFolding.cpp File Reference

#include "BranchFolding.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/LivePhysRegs.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/Function.h"
#include "llvm/MC/LaneBitmask.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/BlockFrequency.h"
#include "llvm/Support/BranchProbability.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include <cassert>
#include <cstddef>
#include <iterator>
#include <numeric>
#include <vector>

Include dependency graph for BranchFolding.cpp:

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "branch-folder"

Functions
	STATISTIC (NumDeadBlocks, "Number of dead blocks removed")
	STATISTIC (NumBranchOpts, "Number of branches optimized")
	STATISTIC (NumTailMerge, "Number of block tails merged")
	STATISTIC (NumHoist, "Number of times common instructions are hoisted")
	STATISTIC (NumTailCalls, "Number of tail calls optimized")
	INITIALIZE_PASS (BranchFolderPass, DEBUG_TYPE, "Control Flow Optimizer", false, false) bool BranchFolderPass
static unsigned	HashMachineInstr (const MachineInstr &MI)
	HashMachineInstr - Compute a hash value for MI and its operands. More...
static unsigned	HashEndOfMBB (const MachineBasicBlock &MBB)
	HashEndOfMBB - Hash the last instruction in the MBB. More...
static bool	countsAsInstruction (const MachineInstr &MI)
	Whether MI should be counted as an instruction when calculating common tail. More...
static unsigned	ComputeCommonTailLength (MachineBasicBlock *MBB1, MachineBasicBlock *MBB2, MachineBasicBlock::iterator &I1, MachineBasicBlock::iterator &I2)
	ComputeCommonTailLength - Given two machine basic blocks, compute the number of instructions they actually have in common together at their end. More...
static unsigned	EstimateRuntime (MachineBasicBlock::iterator I, MachineBasicBlock::iterator E)
	EstimateRuntime - Make a rough estimate for how long it will take to run the specified code. More...
static void	FixTail (MachineBasicBlock *CurMBB, MachineBasicBlock *SuccBB, const TargetInstrInfo *TII)
static unsigned	CountTerminators (MachineBasicBlock *MBB, MachineBasicBlock::iterator &I)
	CountTerminators - Count the number of terminators in the given block and set I to the position of the first non-terminator, if there is one, or MBB->end() otherwise. More...
static bool	blockEndsInUnreachable (const MachineBasicBlock *MBB)
	A no successor, non-return block probably ends in unreachable and is cold. More...
static bool	ProfitableToMerge (MachineBasicBlock *MBB1, MachineBasicBlock *MBB2, unsigned MinCommonTailLength, unsigned &CommonTailLen, MachineBasicBlock::iterator &I1, MachineBasicBlock::iterator &I2, MachineBasicBlock *SuccBB, MachineBasicBlock *PredBB, DenseMap< const MachineBasicBlock *, int > &EHScopeMembership, bool AfterPlacement)
	ProfitableToMerge - Check if two machine basic blocks have a common tail and decide if it would be profitable to merge those tails. More...
static void	mergeOperations (MachineBasicBlock::iterator MBBIStartPos, MachineBasicBlock &MBBCommon)
static bool	IsEmptyBlock (MachineBasicBlock *MBB)
static bool	IsBranchOnlyBlock (MachineBasicBlock *MBB)
static bool	IsBetterFallthrough (MachineBasicBlock *MBB1, MachineBasicBlock *MBB2)
	IsBetterFallthrough - Return true if it would be clearly better to fall-through to MBB1 than to fall through into MBB2. More...
static DebugLoc	getBranchDebugLoc (MachineBasicBlock &MBB)
	getBranchDebugLoc - Find and return, if any, the DebugLoc of the branch instructions on the block. More...
static void	copyDebugInfoToPredecessor (const TargetInstrInfo *TII, MachineBasicBlock &MBB, MachineBasicBlock &PredMBB)
static void	copyDebugInfoToSuccessor (const TargetInstrInfo *TII, MachineBasicBlock &MBB, MachineBasicBlock &SuccMBB)
static void	salvageDebugInfoFromEmptyBlock (const TargetInstrInfo *TII, MachineBasicBlock &MBB)
static MachineBasicBlock *	findFalseBlock (MachineBasicBlock *BB, MachineBasicBlock *TrueBB)
	findFalseBlock - BB has a fallthrough. More...
template<class Container >
static void	addRegAndItsAliases (unsigned Reg, const TargetRegisterInfo *TRI, Container &Set)
static MachineBasicBlock::iterator	findHoistingInsertPosAndDeps (MachineBasicBlock *MBB, const TargetInstrInfo *TII, const TargetRegisterInfo *TRI, SmallSet< unsigned, 4 > &Uses, SmallSet< unsigned, 4 > &Defs)
	findHoistingInsertPosAndDeps - Find the location to move common instructions in successors to. More...

Variables
static cl::opt< cl::boolOrDefault >	FlagEnableTailMerge ("enable-tail-merge", cl::init(cl::BOU_UNSET), cl::Hidden)
static cl::opt< unsigned >	TailMergeThreshold ("tail-merge-threshold", cl::desc("Max number of predecessors to consider tail merging"), cl::init(150), cl::Hidden)
static cl::opt< unsigned >	TailMergeSize ("tail-merge-size", cl::desc("Min number of instructions to consider tail merging"), cl::init(3), cl::Hidden)

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "branch-folder"

Definition at line 68 of file BranchFolding.cpp.

Function Documentation

addRegAndItsAliases()

template<class Container >

static void addRegAndItsAliases ( unsigned  Reg, const TargetRegisterInfo *  TRI, Container &  Set  )

static

Definition at line 1870 of file BranchFolding.cpp.

References llvm::TargetRegisterInfo::isPhysicalRegister(), and llvm::MCRegAliasIterator::isValid().

Referenced by findHoistingInsertPosAndDeps().

blockEndsInUnreachable()

static bool blockEndsInUnreachable ( const MachineBasicBlock *  MBB )

static

A no successor, non-return block probably ends in unreachable and is cold.

Also consider a block that ends in an indirect branch to be a return block, since many targets use plain indirect branches to return.

Definition at line 608 of file BranchFolding.cpp.

References llvm::MachineBasicBlock::back(), llvm::MachineBasicBlock::empty(), llvm::MachineInstr::isIndirectBranch(), llvm::MachineInstr::isReturn(), and llvm::MachineBasicBlock::succ_empty().

Referenced by ProfitableToMerge().

ComputeCommonTailLength()

static unsigned ComputeCommonTailLength ( MachineBasicBlock *  MBB1, MachineBasicBlock *  MBB2, MachineBasicBlock::iterator &  I1, MachineBasicBlock::iterator &  I2  )

static

ComputeCommonTailLength - Given two machine basic blocks, compute the number of instructions they actually have in common together at their end.

Return iterators for the first shared instruction in each block.

Definition at line 307 of file BranchFolding.cpp.

References llvm::LivePhysRegs::addLiveOuts(), llvm::MachineBasicBlock::addSuccessor(), assert(), llvm::LivePhysRegs::available(), llvm::MachineBasicBlock::begin(), llvm::BuildMI(), llvm::LivePhysRegs::clear(), llvm::computeAndAddLiveIns(), countsAsInstruction(), llvm::MachineFunction::CreateMachineBasicBlock(), llvm::MachineBasicBlock::end(), llvm::MCInstrInfo::get(), llvm::LaneBitmask::getAll(), llvm::MachineLoopInfo::getBase(), llvm::BranchFolder::MBFIWrapper::getBlockFreq(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::MachineLoopInfo::getLoopFor(), llvm::MachineBasicBlock::getParent(), I, llvm::MachineFunction::insert(), llvm::TargetInstrInfo::isLegalToSplitMBBAt(), llvm::MachineBasicBlock::liveins(), P, Reg, llvm::TargetInstrInfo::ReplaceTailWithBranchTo(), llvm::BranchFolder::MBFIWrapper::setBlockFreq(), llvm::MachineBasicBlock::splice(), llvm::LivePhysRegs::stepBackward(), and llvm::MachineBasicBlock::transferSuccessors().

Referenced by ProfitableToMerge().

copyDebugInfoToPredecessor()

static void copyDebugInfoToPredecessor ( const TargetInstrInfo *  TII, MachineBasicBlock &  MBB, MachineBasicBlock &  PredMBB  )

static

Definition at line 1361 of file BranchFolding.cpp.

References llvm::dbgs(), llvm::TargetInstrInfo::duplicate(), llvm::MachineBasicBlock::getFirstTerminator(), llvm::MachineBasicBlock::instrs(), LLVM_DEBUG, and MI.

Referenced by salvageDebugInfoFromEmptyBlock().

copyDebugInfoToSuccessor()

static void copyDebugInfoToSuccessor ( const TargetInstrInfo *  TII, MachineBasicBlock &  MBB, MachineBasicBlock &  SuccMBB  )

static

Definition at line 1373 of file BranchFolding.cpp.

References llvm::MachineBasicBlock::begin(), llvm::dbgs(), llvm::TargetInstrInfo::duplicate(), llvm::MachineBasicBlock::instrs(), LLVM_DEBUG, MI, and llvm::MachineBasicBlock::SkipPHIsAndLabels().

Referenced by salvageDebugInfoFromEmptyBlock().

countsAsInstruction()

static bool countsAsInstruction ( const MachineInstr &  MI )

static

Whether MI should be counted as an instruction when calculating common tail.

Definition at line 300 of file BranchFolding.cpp.

References llvm::MachineInstr::isCFIInstruction(), and llvm::MachineInstr::isDebugInstr().

Referenced by ComputeCommonTailLength(), EstimateRuntime(), and mergeOperations().

CountTerminators()

static unsigned CountTerminators ( MachineBasicBlock *  MBB, MachineBasicBlock::iterator &  I  )

static

CountTerminators - Count the number of terminators in the given block and set I to the position of the first non-terminator, if there is one, or MBB->end() otherwise.

Definition at line 589 of file BranchFolding.cpp.

References llvm::MachineBasicBlock::begin(), llvm::MachineBasicBlock::end(), and I.

Referenced by ProfitableToMerge().

EstimateRuntime()

static unsigned EstimateRuntime ( MachineBasicBlock::iterator  I, MachineBasicBlock::iterator  E  )

static

EstimateRuntime - Make a rough estimate for how long it will take to run the specified code.

Definition at line 490 of file BranchFolding.cpp.

References countsAsInstruction(), E, and I.

Referenced by ProfitableToMerge().

findFalseBlock()

static MachineBasicBlock* findFalseBlock ( MachineBasicBlock *  BB, MachineBasicBlock *  TrueBB  )

static

findFalseBlock - BB has a fallthrough.

Find its 'false' successor given its 'true' successor.

Definition at line 1861 of file BranchFolding.cpp.

References llvm::MachineBasicBlock::successors().

Referenced by findHoistingInsertPosAndDeps().

findHoistingInsertPosAndDeps()

static MachineBasicBlock::iterator findHoistingInsertPosAndDeps ( MachineBasicBlock *  MBB, const TargetInstrInfo *  TII, const TargetRegisterInfo *  TRI, SmallSet< unsigned, 4 > &  Uses, SmallSet< unsigned, 4 > &  Defs  )

static

findHoistingInsertPosAndDeps - Find the location to move common instructions in successors to.

The location is usually just before the terminator, however if the terminator is a conditional branch and its previous instruction is the flag setting instruction, the previous instruction is the preferred location. This function also gathers uses and defs of the instructions from the insertion point to the end of the block. The data is used by HoistCommonCodeInSuccs to ensure safety.

Definition at line 1888 of file BranchFolding.cpp.

References addRegAndItsAliases(), llvm::TargetInstrInfo::analyzeBranch(), llvm::MachineBasicBlock::begin(), llvm::MachineInstr::CheckKillDead, llvm::SmallSet< T, N, C >::count(), llvm::SmallVectorBase::empty(), llvm::SmallSet< T, N, C >::empty(), llvm::MachineBasicBlock::end(), llvm::SmallSet< T, N, C >::erase(), findFalseBlock(), llvm::MachineBasicBlock::getFirstTerminator(), llvm::TargetRegisterInfo::isPhysicalRegister(), llvm::TargetInstrInfo::isPredicated(), llvm::TargetInstrInfo::isUnpredicatedTerminator(), llvm::MCRegisterInfo::DiffListIterator::isValid(), llvm::MCRegAliasIterator::isValid(), llvm::TargetRegisterInfo::isVirtualRegister(), llvm::MachineBasicBlock::pred_size(), llvm::recomputeLiveIns(), Reg, llvm::skipDebugInstructionsBackward(), llvm::skipDebugInstructionsForward(), and llvm::MachineBasicBlock::splice().

FixTail()

static void FixTail ( MachineBasicBlock *  CurMBB, MachineBasicBlock *  SuccBB, const TargetInstrInfo *  TII  )

static

Definition at line 510 of file BranchFolding.cpp.

References llvm::TargetInstrInfo::analyzeBranch(), llvm::SmallVectorBase::empty(), llvm::MachineFunction::end(), llvm::MachineBasicBlock::findBranchDebugLoc(), llvm::MachineBasicBlock::getParent(), I, llvm::TargetInstrInfo::insertBranch(), llvm_unreachable, llvm::operator<(), llvm::TargetInstrInfo::removeBranch(), and llvm::TargetInstrInfo::reverseBranchCondition().

Referenced by mergeOperations(), and ProfitableToMerge().

getBranchDebugLoc()

static DebugLoc getBranchDebugLoc ( MachineBasicBlock &  MBB )

static

getBranchDebugLoc - Find and return, if any, the DebugLoc of the branch instructions on the block.

Definition at line 1354 of file BranchFolding.cpp.

References llvm::MachineBasicBlock::end(), llvm::MachineBasicBlock::getLastNonDebugInstr(), and I.

Referenced by salvageDebugInfoFromEmptyBlock().

HashEndOfMBB()

static unsigned HashEndOfMBB ( const MachineBasicBlock &  MBB )

static

HashEndOfMBB - Hash the last instruction in the MBB.

Definition at line 291 of file BranchFolding.cpp.

References llvm::MachineBasicBlock::end(), llvm::MachineBasicBlock::getLastNonDebugInstr(), HashMachineInstr(), and I.

Referenced by mergeOperations().

HashMachineInstr()

static unsigned HashMachineInstr ( const MachineInstr &  MI )

static

HashMachineInstr - Compute a hash value for MI and its operands.

Definition at line 251 of file BranchFolding.cpp.

References llvm::MachineOperand::getImm(), llvm::MachineOperand::getIndex(), llvm::MachineOperand::getMBB(), llvm::MachineBasicBlock::getNumber(), llvm::MachineInstr::getNumOperands(), llvm::MachineOperand::getOffset(), llvm::MachineInstr::getOpcode(), llvm::MachineInstr::getOperand(), llvm::MachineOperand::getReg(), llvm::MachineOperand::getType(), llvm::MachineOperand::MO_ConstantPoolIndex, llvm::MachineOperand::MO_ExternalSymbol, llvm::MachineOperand::MO_FrameIndex, llvm::MachineOperand::MO_GlobalAddress, llvm::MachineOperand::MO_Immediate, llvm::MachineOperand::MO_JumpTableIndex, llvm::MachineOperand::MO_MachineBasicBlock, and llvm::MachineOperand::MO_Register.

Referenced by HashEndOfMBB().

INITIALIZE_PASS()

INITIALIZE_PASS	(	BranchFolderPass	,
		DEBUG_TYPE	,
		"Control Flow Optimizer"	,
		false	,
		false
	)

Definition at line 117 of file BranchFolding.cpp.

References llvm::TargetPassConfig::getEnableTailMerge(), and llvm::BranchFolder::OptimizeFunction().

IsBetterFallthrough()

static bool IsBetterFallthrough ( MachineBasicBlock *  MBB1, MachineBasicBlock *  MBB2  )

static

IsBetterFallthrough - Return true if it would be clearly better to fall-through to MBB1 than to fall through into MBB2.

This has to return a strict ordering, returning true for both (MBB1,MBB2) and (MBB2,MBB1) will result in infinite loops.

Definition at line 1333 of file BranchFolding.cpp.

References llvm::MachineBasicBlock::end(), llvm::MachineBasicBlock::getLastNonDebugInstr(), and llvm::MachineBasicBlock::isSuccessor().

Referenced by salvageDebugInfoFromEmptyBlock().

IsBranchOnlyBlock()

static bool IsBranchOnlyBlock ( MachineBasicBlock *  MBB )

static

Definition at line 1323 of file BranchFolding.cpp.

References assert(), llvm::MachineBasicBlock::end(), llvm::MachineBasicBlock::getFirstNonDebugInstr(), and I.

Referenced by salvageDebugInfoFromEmptyBlock().

IsEmptyBlock()

static bool IsEmptyBlock ( MachineBasicBlock *  MBB )

static

Definition at line 1317 of file BranchFolding.cpp.

References llvm::MachineBasicBlock::end(), and llvm::MachineBasicBlock::getFirstNonDebugInstr().

Referenced by salvageDebugInfoFromEmptyBlock().

mergeOperations()

static void mergeOperations ( MachineBasicBlock::iterator  MBBIStartPos, MachineBasicBlock &  MBBCommon  )

static

Definition at line 835 of file BranchFolding.cpp.

References llvm::addLiveIns(), llvm::LivePhysRegs::addLiveOuts(), llvm::TargetInstrInfo::analyzeBranch(), llvm::array_pod_sort(), assert(), llvm::LivePhysRegs::available(), llvm::MachineBasicBlock::begin(), llvm::MachineFunction::begin(), llvm::BuildMI(), llvm::LivePhysRegs::clear(), llvm::computeLiveIns(), countsAsInstruction(), llvm::dbgs(), E, llvm::SmallVectorBase::empty(), llvm::sys::path::end(), llvm::MachineBasicBlock::end(), llvm::MachineFunction::end(), FixTail(), llvm::MCInstrInfo::get(), llvm::BranchFolder::MBFIWrapper::getBlockFreq(), llvm::BranchProbability::getBranchProbability(), llvm::MachineBranchProbabilityInfo::getEdgeProbability(), llvm::getEHScopeMembership(), llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::MachineLoopInfo::getLoopFor(), llvm::DILocation::getMergedLocation(), llvm::MachineBasicBlock::getParent(), HashEndOfMBB(), I, llvm::LivePhysRegs::init(), llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::TargetInstrInfo::insertBranch(), llvm::MachineBasicBlock::isEHPad(), llvm::MachineOperand::isReg(), llvm::MachineOperand::isUndef(), LLVM_DEBUG, MI, llvm::MachineBasicBlock::pred_empty(), llvm::MachineBasicBlock::predecessors(), llvm::printMBBReference(), llvm::MachineBasicBlock::rbegin(), Reg, llvm::TargetInstrInfo::removeBranch(), llvm::MachineBasicBlock::rend(), llvm::MachineFunction::RenumberBlocks(), llvm::TargetInstrInfo::reverseBranchCondition(), llvm::BranchFolder::MBFIWrapper::setBlockFreq(), llvm::MachineOperand::setIsUndef(), llvm::MachineBasicBlock::setSuccProbability(), llvm::MachineBasicBlock::succ_begin(), llvm::MachineBasicBlock::succ_empty(), llvm::MachineBasicBlock::succ_end(), llvm::MachineBasicBlock::succ_size(), and TailMergeThreshold.

ProfitableToMerge()

static bool ProfitableToMerge ( MachineBasicBlock *  MBB1, MachineBasicBlock *  MBB2, unsigned  MinCommonTailLength, unsigned &  CommonTailLen, MachineBasicBlock::iterator &  I1, MachineBasicBlock::iterator &  I2, MachineBasicBlock *  SuccBB, MachineBasicBlock *  PredBB, DenseMap< const MachineBasicBlock *, int > &  EHScopeMembership, bool  AfterPlacement  )

static

ProfitableToMerge - Check if two machine basic blocks have a common tail and decide if it would be profitable to merge those tails.

Return the length of the common tail and iterators to the first common instruction in each block. MBB1, MBB2 The blocks to check MinCommonTailLength Minimum size of tail block to be merged. CommonTailLen Out parameter to record the size of the shared tail between MBB1 and MBB2 I1, I2 Iterator references that will be changed to point to the first instruction in the common tail shared by MBB1,MBB2 SuccBB A common successor of MBB1, MBB2 which are in a canonical form relative to SuccBB PredBB The layout predecessor of SuccBB, if any. EHScopeMembership map from block to EH scope #. AfterPlacement True if we are merging blocks after layout. Stricter thresholds apply to prevent undoing tail-duplication.

Definition at line 633 of file BranchFolding.cpp.

References assert(), B, llvm::MachineBasicBlock::back(), llvm::sys::path::begin(), llvm::MachineBasicBlock::begin(), llvm::MachineFunction::begin(), blockEndsInUnreachable(), llvm::MachineBasicBlock::canFallThrough(), ComputeCommonTailLength(), CountTerminators(), llvm::dbgs(), llvm::DenseMapBase< DenseMap< KeyT, ValueT, KeyInfoT, BucketT >, KeyT, ValueT, KeyInfoT, BucketT >::empty(), llvm::DenseMapBase< DenseMap< KeyT, ValueT, KeyInfoT, BucketT >, KeyT, ValueT, KeyInfoT, BucketT >::end(), EstimateRuntime(), llvm::DenseMapBase< DenseMap< KeyT, ValueT, KeyInfoT, BucketT >, KeyT, ValueT, KeyInfoT, BucketT >::find(), FixTail(), llvm::MachineBasicBlock::getBasicBlock(), llvm::MachineFunction::getFunction(), llvm::MachineBasicBlock::getParent(), I, llvm::MachineInstr::isBarrier(), llvm::MachineBasicBlock::isLayoutSuccessor(), LLVM_DEBUG, llvm::Function::optForSize(), llvm::printMBBReference(), and llvm::MachineBasicBlock::succ_size().

salvageDebugInfoFromEmptyBlock()

static void salvageDebugInfoFromEmptyBlock ( const TargetInstrInfo *  TII, MachineBasicBlock &  MBB  )

static

Definition at line 1392 of file BranchFolding.cpp.

References llvm::TargetInstrInfo::analyzeBranch(), assert(), llvm::MachineFunction::back(), llvm::MachineBasicBlock::begin(), llvm::MachineFunction::begin(), llvm::MachineBasicBlock::canFallThrough(), llvm::TargetInstrInfo::canMakeTailCallConditional(), llvm::SmallVectorImpl< T >::clear(), copyDebugInfoToPredecessor(), copyDebugInfoToSuccessor(), llvm::MachineBasicBlock::CorrectExtraCFGEdges(), llvm::dbgs(), E, llvm::SmallVectorBase::empty(), llvm::MachineBasicBlock::empty(), llvm::MachineBasicBlock::end(), llvm::MachineFunction::end(), llvm::MachineBasicBlock::erase(), llvm::MachineInstr::eraseFromParent(), getBranchDebugLoc(), llvm::MachineBasicBlock::getFirstNonDebugInstr(), llvm::MachineFunction::getFunction(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::MachineFunction::getJumpTableInfo(), llvm::MachineBasicBlock::getNumber(), llvm::MachineBasicBlock::getParent(), llvm::MachineBasicBlock::hasAddressTaken(), I, llvm::TargetInstrInfo::insertBranch(), IsBetterFallthrough(), IsBranchOnlyBlock(), llvm::MachineBasicBlock::isEHPad(), IsEmptyBlock(), llvm::MachineBasicBlock::isSuccessor(), llvm::TargetInstrInfo::isUnconditionalTailCall(), LLVM_DEBUG, llvm::MachineBasicBlock::moveAfter(), llvm::MachineBasicBlock::moveBefore(), llvm::Function::optForSize(), llvm::MachineBasicBlock::pred_begin(), llvm::MachineBasicBlock::pred_empty(), llvm::MachineBasicBlock::pred_end(), llvm::MachineBasicBlock::pred_size(), llvm::MachineBasicBlock::predecessors(), llvm::TargetInstrInfo::removeBranch(), llvm::MachineBasicBlock::removeSuccessor(), llvm::TargetInstrInfo::replaceBranchWithTailCall(), llvm::MachineBasicBlock::ReplaceUsesOfBlockWith(), llvm::TargetInstrInfo::reverseBranchCondition(), llvm::MachineBasicBlock::splice(), llvm::MachineBasicBlock::succ_begin(), llvm::MachineBasicBlock::succ_empty(), llvm::MachineBasicBlock::succ_size(), llvm::MachineBasicBlock::successors(), llvm::MipsISD::TailCall, and llvm::MachineBasicBlock::transferSuccessors().

STATISTIC() [1/5]

STATISTIC	(	NumDeadBlocks	,
		"Number of dead blocks removed"
	)

STATISTIC() [2/5]

STATISTIC	(	NumBranchOpts	,
		"Number of branches optimized"
	)

STATISTIC() [3/5]

STATISTIC	(	NumTailMerge	,
		"Number of block tails merged"
	)

STATISTIC() [4/5]

STATISTIC	(	NumHoist	,
		"Number of times common instructions are hoisted"
	)

STATISTIC() [5/5]

STATISTIC	(	NumTailCalls	,
		"Number of tail calls optimized"
	)

Variable Documentation

FlagEnableTailMerge

cl::opt<cl::boolOrDefault> FlagEnableTailMerge("enable-tail-merge", cl::init(cl::BOU_UNSET), cl::Hidden)

static

Referenced by llvm::BranchFolder::BranchFolder().

TailMergeSize

cl::opt<unsigned> TailMergeSize("tail-merge-size", cl::desc("Min number of instructions to consider tail merging"), cl::init(3), cl::Hidden)

static

Referenced by llvm::BranchFolder::BranchFolder(), and getLayoutSuccessorProbThreshold().

TailMergeThreshold

cl::opt<unsigned> TailMergeThreshold("tail-merge-threshold", cl::desc("Max number of predecessors to consider tail merging"), cl::init(150), cl::Hidden)

static

Referenced by mergeOperations().