LoopUnswitch.cpp File Reference

#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionTracker.h"
#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
#include <map>
#include <set>

Include dependency graph for LoopUnswitch.cpp:

Go to the source code of this file.

Defines
#define	DEBUG_TYPE   "loop-unswitch"
Functions
	STATISTIC (NumBranches,"Number of branches unswitched")
	STATISTIC (NumSwitches,"Number of switches unswitched")
	STATISTIC (NumSelects,"Number of selects unswitched")
	STATISTIC (NumTrivial,"Number of unswitches that are trivial")
	STATISTIC (NumSimplify,"Number of simplifications of unswitched code")
	STATISTIC (TotalInsts,"Total number of instructions analyzed")
	INITIALIZE_PASS_BEGIN (LoopUnswitch,"loop-unswitch","Unswitch loops", false, false) INITIALIZE_PASS_END(LoopUnswitch
static Value *	FindLIVLoopCondition (Value *Cond, Loop *L, bool &Changed)
static bool	isTrivialLoopExitBlockHelper (Loop *L, BasicBlock *BB, BasicBlock *&ExitBB, std::set< BasicBlock * > &Visited)
static BasicBlock *	isTrivialLoopExitBlock (Loop *L, BasicBlock *BB)
static Loop *	CloneLoop (Loop *L, Loop *PL, ValueToValueMapTy &VM, LoopInfo *LI, LPPassManager *LPM)
static void	RemoveFromWorklist (Instruction *I, std::vector< Instruction * > &Worklist)
static void	ReplaceUsesOfWith (Instruction *I, Value *V, std::vector< Instruction * > &Worklist, Loop *L, LPPassManager *LPM)
Variables
static cl::opt< unsigned >	Threshold ("loop-unswitch-threshold", cl::desc("Max loop size to unswitch"), cl::init(100), cl::Hidden)
loop	unswitch
loop Unswitch	loops
loop Unswitch	false

---

Define Documentation

#define DEBUG_TYPE   "loop-unswitch"

Definition at line 56 of file LoopUnswitch.cpp.

---

Function Documentation

static Loop* CloneLoop	(	Loop *	L,
		Loop *	PL,
		ValueToValueMapTy &	VM,
		LoopInfo *	LI,
		LPPassManager *	LPM
	)		[static]

CloneLoop - Recursively clone the specified loop and all of its children, mapping the blocks with the specified map.

Definition at line 668 of file LoopUnswitch.cpp.

References llvm::LoopBase< BlockT, LoopT >::addBasicBlockToLoop(), llvm::LoopBase< BlockT, LoopT >::begin(), llvm::LoopBase< BlockT, LoopT >::block_begin(), llvm::LoopBase< BlockT, LoopT >::block_end(), llvm::LoopBase< BlockT, LoopT >::end(), llvm::LoopInfo::getBase(), llvm::LoopInfo::getLoopFor(), I, llvm::LPPassManager::insertLoop(), and llvm::GC::Loop.

static Value* FindLIVLoopCondition	(	Value *	Cond,
		Loop *	L,
		bool &	Changed
	)		[static]

FindLIVLoopCondition - Cond is a condition that occurs in L. If it is invariant in the loop, or has an invariant piece, return the invariant. Otherwise, return null.

Definition at line 351 of file LoopUnswitch.cpp.

References llvm::APIntOps::And(), llvm::Value::getType(), llvm::Type::isVectorTy(), llvm::Loop::makeLoopInvariant(), and llvm::APIntOps::Or().

INITIALIZE_PASS_BEGIN	(	LoopUnswitch	,
		"loop-unswitch"	,
		"Unswitch loops"	,
		false	,
		false
	)

static BasicBlock* isTrivialLoopExitBlock	(	Loop *	L,
		BasicBlock *	BB
	)		[static]

isTrivialLoopExitBlock - Return true if the specified block unconditionally leads to an exit from the specified loop, and has no side-effects in the process. If so, return the block that is exited to, otherwise return null.

Definition at line 547 of file LoopUnswitch.cpp.

References llvm::LoopBase< BlockT, LoopT >::getHeader(), and isTrivialLoopExitBlockHelper().

static bool isTrivialLoopExitBlockHelper	(	Loop *	L,
		BasicBlock *	BB,
		BasicBlock *&	ExitBB,
		std::set< BasicBlock * > &	Visited
	)		[static]

isTrivialLoopExitBlock - Check to see if all paths from BB exit the loop with no side effects (including infinite loops).

If true, we return true and set ExitBB to the block we exit through.

Definition at line 512 of file LoopUnswitch.cpp.

References llvm::BasicBlock::begin(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::BasicBlock::end(), I, llvm::succ_begin(), and llvm::succ_end().

Referenced by isTrivialLoopExitBlock().

static void RemoveFromWorklist	(	Instruction *	I,
		std::vector< Instruction * > &	Worklist
	)		[static]

RemoveFromWorklist - Remove all instances of I from the worklist vector specified.

Definition at line 928 of file LoopUnswitch.cpp.

References I, and llvm::LibFunc::remove.

Referenced by ReplaceUsesOfWith().

static void ReplaceUsesOfWith	(	Instruction *	I,
		Value *	V,
		std::vector< Instruction * > &	Worklist,
		Loop *	L,
		LPPassManager *	LPM
	)		[static]

ReplaceUsesOfWith - When we find that I really equals V, remove I from the program, replacing all uses with V and update the worklist.

Definition at line 937 of file LoopUnswitch.cpp.

References llvm::dbgs(), DEBUG, llvm::LPPassManager::deleteSimpleAnalysisValue(), llvm::Instruction::eraseFromParent(), llvm::User::getNumOperands(), llvm::User::getOperand(), RemoveFromWorklist(), llvm::Value::replaceAllUsesWith(), and llvm::Value::users().

STATISTIC	(	NumBranches	,
		"Number of branches unswitched"
	)

STATISTIC	(	NumSwitches	,
		"Number of switches unswitched"
	)

STATISTIC	(	NumSelects	,
		"Number of selects unswitched"
	)

STATISTIC	(	NumTrivial	,
		"Number of unswitches that are trivial"
	)

STATISTIC	(	NumSimplify	,
		"Number of simplifications of unswitched code"
	)

STATISTIC	(	TotalInsts	,
		"Total number of instructions analyzed"
	)

---

Variable Documentation

loop Unswitch false

Definition at line 341 of file LoopUnswitch.cpp.

loop Unswitch loops

Definition at line 341 of file LoopUnswitch.cpp.

cl::opt<unsigned> Threshold("loop-unswitch-threshold", cl::desc("Max loop size to unswitch"), cl::init(100), cl::Hidden) [static]

loop unswitch

Definition at line 341 of file LoopUnswitch.cpp.